- Spectrum Development - spectrum-os.org

[PATCH mktuntap] Become REUSE 3.0 compliant
by Alyssa Ross 31 Jul '20

31 Jul '20

See <https://reuse.software/>. NLnet are quite keen on this. --- .editorconfig | 3 + .gitignore | 7 +- COPYING | 339 ---------------------------------- LICENSES/CC0-1.0.txt | 119 ++++++++++++ LICENSES/GPL-2.0-only.txt | 319 ++++++++++++++++++++++++++++++++ LICENSES/GPL-2.0-or-later.txt | 319 ++++++++++++++++++++++++++++++++ Makefile | 20 +- README | 6 + TODO | 3 + mktuntap.8 | 16 +- mktuntap.c | 28 +-- 11 files changed, 787 insertions(+), 392 deletions(-) delete mode 100644 COPYING create mode 100644 LICENSES/CC0-1.0.txt create mode 100644 LICENSES/GPL-2.0-only.txt create mode 100644 LICENSES/GPL-2.0-or-later.txt diff --git a/.editorconfig b/.editorconfig index 35c5fb2..49f3188 100644 --- a/.editorconfig +++ b/.editorconfig @@ -1,3 +1,6 @@ +# SPDX-FileCopyrightText: 2019 Alyssa Ross <hi(a)alyssa.is> +# SPDX-License-Identifier: CC0-1.0 + root = true [*] diff --git a/.gitignore b/.gitignore index 7e27746..9106912 100644 --- a/.gitignore +++ b/.gitignore @@ -1,4 +1,9 @@ +# SPDX-FileCopyrightText: 2019 Alyssa Ross <hi(a)alyssa.is> +# SPDX-License-Identifier: CC0-1.0 + result result-* *.o -/mktuntap \ No newline at end of file +/mktuntap +bindunix +socketpair diff --git a/COPYING b/COPYING deleted file mode 100644 index d159169..0000000 --- a/COPYING +++ /dev/null @@ -1,339 +0,0 @@ - GNU GENERAL PUBLIC LICENSE - Version 2, June 1991 - - Copyright (C) 1989, 1991 Free Software Foundation, Inc., - 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA - Everyone is permitted to copy and distribute verbatim copies - of this license document, but changing it is not allowed. - - Preamble - - The licenses for most software are designed to take away your -freedom to share and change it. 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However, as a special exception, the source code distributed +need not include anything that is normally distributed (in either source or +binary form) with the major components (compiler, kernel, and so on) of the +operating system on which the executable runs, unless that component itself +accompanies the executable. + +If distribution of executable or object code is made by offering access to +copy from a designated place, then offering equivalent access to copy the +source code from the same place counts as distribution of the source code, +even though third parties are not compelled to copy the source along with +the object code. + +4. You may not copy, modify, sublicense, or distribute the Program except +as expressly provided under this License. Any attempt otherwise to copy, modify, +sublicense or distribute the Program is void, and will automatically terminate +your rights under this License. However, parties who have received copies, +or rights, from you under this License will not have their licenses terminated +so long as such parties remain in full compliance. + +5. You are not required to accept this License, since you have not signed +it. However, nothing else grants you permission to modify or distribute the +Program or its derivative works. These actions are prohibited by law if you +do not accept this License. Therefore, by modifying or distributing the Program +(or any work based on the Program), you indicate your acceptance of this License +to do so, and all its terms and conditions for copying, distributing or modifying +the Program or works based on it. + +6. Each time you redistribute the Program (or any work based on the Program), +the recipient automatically receives a license from the original licensor +to copy, distribute or modify the Program subject to these terms and conditions. +You may not impose any further restrictions on the recipients' exercise of +the rights granted herein. You are not responsible for enforcing compliance +by third parties to this License. + +7. If, as a consequence of a court judgment or allegation of patent infringement +or for any other reason (not limited to patent issues), conditions are imposed +on you (whether by court order, agreement or otherwise) that contradict the +conditions of this License, they do not excuse you from the conditions of +this License. If you cannot distribute so as to satisfy simultaneously your +obligations under this License and any other pertinent obligations, then as +a consequence you may not distribute the Program at all. For example, if a +patent license would not permit royalty-free redistribution of the Program +by all those who receive copies directly or indirectly through you, then the +only way you could satisfy both it and this License would be to refrain entirely +from distribution of the Program. + +If any portion of this section is held invalid or unenforceable under any +particular circumstance, the balance of the section is intended to apply and +the section as a whole is intended to apply in other circumstances. + +It is not the purpose of this section to induce you to infringe any patents +or other property right claims or to contest validity of any such claims; +this section has the sole purpose of protecting the integrity of the free +software distribution system, which is implemented by public license practices. +Many people have made generous contributions to the wide range of software +distributed through that system in reliance on consistent application of that +system; it is up to the author/donor to decide if he or she is willing to +distribute software through any other system and a licensee cannot impose +that choice. + +This section is intended to make thoroughly clear what is believed to be a +consequence of the rest of this License. + +8. If the distribution and/or use of the Program is restricted in certain +countries either by patents or by copyrighted interfaces, the original copyright +holder who places the Program under this License may add an explicit geographical +distribution limitation excluding those countries, so that distribution is +permitted only in or among countries not thus excluded. In such case, this +License incorporates the limitation as if written in the body of this License. + +9. The Free Software Foundation may publish revised and/or new versions of +the General Public License from time to time. Such new versions will be similar +in spirit to the present version, but may differ in detail to address new +problems or concerns. + +Each version is given a distinguishing version number. If the Program specifies +a version number of this License which applies to it and "any later version", +you have the option of following the terms and conditions either of that version +or of any later version published by the Free Software Foundation. If the +Program does not specify a version number of this License, you may choose +any version ever published by the Free Software Foundation. + +10. If you wish to incorporate parts of the Program into other free programs +whose distribution conditions are different, write to the author to ask for +permission. For software which is copyrighted by the Free Software Foundation, +write to the Free Software Foundation; we sometimes make exceptions for this. +Our decision will be guided by the two goals of preserving the free status +of all derivatives of our free software and of promoting the sharing and reuse +of software generally. + + NO WARRANTY + +11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR +THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE +STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM +"AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, +BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS +FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE +OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME +THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. + +12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING +WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE +THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY +GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE +OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA +OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES +OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH +HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. +END OF TERMS AND CONDITIONS + +How to Apply These Terms to Your New Programs + +If you develop a new program, and you want it to be of the greatest possible +use to the public, the best way to achieve this is to make it free software +which everyone can redistribute and change under these terms. + +To do so, attach the following notices to the program. It is safest to attach +them to the start of each source file to most effectively convey the exclusion +of warranty; and each file should have at least the "copyright" line and a +pointer to where the full notice is found. + +<one line to give the program's name and an idea of what it does.> + +Copyright (C)< yyyy> <name of author> + +This program is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free Software +Foundation; either version 2 of the License, or (at your option) any later +version. + +This program is distributed in the hope that it will be useful, but WITHOUT +ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS +FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. + +You should have received a copy of the GNU General Public License along with +this program; if not, write to the Free Software Foundation, Inc., 51 Franklin +Street, Fifth Floor, Boston, MA 02110-1301, USA. + +Also add information on how to contact you by electronic and paper mail. + +If the program is interactive, make it output a short notice like this when +it starts in an interactive mode: + +Gnomovision version 69, Copyright (C) year name of author Gnomovision comes +with ABSOLUTELY NO WARRANTY; for details type `show w'. This is free software, +and you are welcome to redistribute it under certain conditions; type `show +c' for details. + +The hypothetical commands `show w' and `show c' should show the appropriate +parts of the General Public License. Of course, the commands you use may be +called something other than `show w' and `show c'; they could even be mouse-clicks +or menu items--whatever suits your program. + +You should also get your employer (if you work as a programmer) or your school, +if any, to sign a "copyright disclaimer" for the program, if necessary. Here +is a sample; alter the names: + +Yoyodyne, Inc., hereby disclaims all copyright interest in the program `Gnomovision' +(which makes passes at compilers) written by James Hacker. + +<signature of Ty Coon >, 1 April 1989 Ty Coon, President of Vice This General +Public License does not permit incorporating your program into proprietary +programs. If your program is a subroutine library, you may consider it more +useful to permit linking proprietary applications with the library. If this +is what you want to do, use the GNU Lesser General Public License instead +of this License. diff --git a/LICENSES/GPL-2.0-or-later.txt b/LICENSES/GPL-2.0-or-later.txt new file mode 100644 index 0000000..1d80ac3 --- /dev/null +++ b/LICENSES/GPL-2.0-or-later.txt @@ -0,0 +1,319 @@ +GNU GENERAL PUBLIC LICENSE + +Version 2, June 1991 + +Copyright (C) 1989, 1991 Free Software Foundation, Inc. + +51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA + +Everyone is permitted to copy and distribute verbatim copies of this license +document, but changing it is not allowed. + +Preamble + +The licenses for most software are designed to take away your freedom to share +and change it. By contrast, the GNU General Public License is intended to +guarantee your freedom to share and change free software--to make sure the +software is free for all its users. This General Public License applies to +most of the Free Software Foundation's software and to any other program whose +authors commit to using it. (Some other Free Software Foundation software +is covered by the GNU Lesser General Public License instead.) You can apply +it to your programs, too. + +When we speak of free software, we are referring to freedom, not price. Our +General Public Licenses are designed to make sure that you have the freedom +to distribute copies of free software (and charge for this service if you +wish), that you receive source code or can get it if you want it, that you +can change the software or use pieces of it in new free programs; and that +you know you can do these things. + +To protect your rights, we need to make restrictions that forbid anyone to +deny you these rights or to ask you to surrender the rights. These restrictions +translate to certain responsibilities for you if you distribute copies of +the software, or if you modify it. + +For example, if you distribute copies of such a program, whether gratis or +for a fee, you must give the recipients all the rights that you have. You +must make sure that they, too, receive or can get the source code. And you +must show them these terms so they know their rights. + +We protect your rights with two steps: (1) copyright the software, and (2) +offer you this license which gives you legal permission to copy, distribute +and/or modify the software. + +Also, for each author's protection and ours, we want to make certain that +everyone understands that there is no warranty for this free software. If +the software is modified by someone else and passed on, we want its recipients +to know that what they have is not the original, so that any problems introduced +by others will not reflect on the original authors' reputations. + +Finally, any free program is threatened constantly by software patents. We +wish to avoid the danger that redistributors of a free program will individually +obtain patent licenses, in effect making the program proprietary. To prevent +this, we have made it clear that any patent must be licensed for everyone's +free use or not licensed at all. + +The precise terms and conditions for copying, distribution and modification +follow. + +TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION + +0. This License applies to any program or other work which contains a notice +placed by the copyright holder saying it may be distributed under the terms +of this General Public License. The "Program", below, refers to any such program +or work, and a "work based on the Program" means either the Program or any +derivative work under copyright law: that is to say, a work containing the +Program or a portion of it, either verbatim or with modifications and/or translated +into another language. (Hereinafter, translation is included without limitation +in the term "modification".) Each licensee is addressed as "you". + +Activities other than copying, distribution and modification are not covered +by this License; they are outside its scope. The act of running the Program +is not restricted, and the output from the Program is covered only if its +contents constitute a work based on the Program (independent of having been +made by running the Program). Whether that is true depends on what the Program +does. + +1. You may copy and distribute verbatim copies of the Program's source code +as you receive it, in any medium, provided that you conspicuously and appropriately +publish on each copy an appropriate copyright notice and disclaimer of warranty; +keep intact all the notices that refer to this License and to the absence +of any warranty; and give any other recipients of the Program a copy of this +License along with the Program. + +You may charge a fee for the physical act of transferring a copy, and you +may at your option offer warranty protection in exchange for a fee. + +2. You may modify your copy or copies of the Program or any portion of it, +thus forming a work based on the Program, and copy and distribute such modifications +or work under the terms of Section 1 above, provided that you also meet all +of these conditions: + +a) You must cause the modified files to carry prominent notices stating that +you changed the files and the date of any change. + +b) You must cause any work that you distribute or publish, that in whole or +in part contains or is derived from the Program or any part thereof, to be +licensed as a whole at no charge to all third parties under the terms of this +License. + +c) If the modified program normally reads commands interactively when run, +you must cause it, when started running for such interactive use in the most +ordinary way, to print or display an announcement including an appropriate +copyright notice and a notice that there is no warranty (or else, saying that +you provide a warranty) and that users may redistribute the program under +these conditions, and telling the user how to view a copy of this License. +(Exception: if the Program itself is interactive but does not normally print +such an announcement, your work based on the Program is not required to print +an announcement.) + +These requirements apply to the modified work as a whole. If identifiable +sections of that work are not derived from the Program, and can be reasonably +considered independent and separate works in themselves, then this License, +and its terms, do not apply to those sections when you distribute them as +separate works. But when you distribute the same sections as part of a whole +which is a work based on the Program, the distribution of the whole must be +on the terms of this License, whose permissions for other licensees extend +to the entire whole, and thus to each and every part regardless of who wrote +it. + +Thus, it is not the intent of this section to claim rights or contest your +rights to work written entirely by you; rather, the intent is to exercise +the right to control the distribution of derivative or collective works based +on the Program. + +In addition, mere aggregation of another work not based on the Program with +the Program (or with a work based on the Program) on a volume of a storage +or distribution medium does not bring the other work under the scope of this +License. + +3. You may copy and distribute the Program (or a work based on it, under Section +2) in object code or executable form under the terms of Sections 1 and 2 above +provided that you also do one of the following: + +a) Accompany it with the complete corresponding machine-readable source code, +which must be distributed under the terms of Sections 1 and 2 above on a medium +customarily used for software interchange; or, + +b) Accompany it with a written offer, valid for at least three years, to give +any third party, for a charge no more than your cost of physically performing +source distribution, a complete machine-readable copy of the corresponding +source code, to be distributed under the terms of Sections 1 and 2 above on +a medium customarily used for software interchange; or, + +c) Accompany it with the information you received as to the offer to distribute +corresponding source code. (This alternative is allowed only for noncommercial +distribution and only if you received the program in object code or executable +form with such an offer, in accord with Subsection b above.) + +The source code for a work means the preferred form of the work for making +modifications to it. For an executable work, complete source code means all +the source code for all modules it contains, plus any associated interface +definition files, plus the scripts used to control compilation and installation +of the executable. However, as a special exception, the source code distributed +need not include anything that is normally distributed (in either source or +binary form) with the major components (compiler, kernel, and so on) of the +operating system on which the executable runs, unless that component itself +accompanies the executable. + +If distribution of executable or object code is made by offering access to +copy from a designated place, then offering equivalent access to copy the +source code from the same place counts as distribution of the source code, +even though third parties are not compelled to copy the source along with +the object code. + +4. You may not copy, modify, sublicense, or distribute the Program except +as expressly provided under this License. Any attempt otherwise to copy, modify, +sublicense or distribute the Program is void, and will automatically terminate +your rights under this License. However, parties who have received copies, +or rights, from you under this License will not have their licenses terminated +so long as such parties remain in full compliance. + +5. You are not required to accept this License, since you have not signed +it. However, nothing else grants you permission to modify or distribute the +Program or its derivative works. These actions are prohibited by law if you +do not accept this License. Therefore, by modifying or distributing the Program +(or any work based on the Program), you indicate your acceptance of this License +to do so, and all its terms and conditions for copying, distributing or modifying +the Program or works based on it. + +6. Each time you redistribute the Program (or any work based on the Program), +the recipient automatically receives a license from the original licensor +to copy, distribute or modify the Program subject to these terms and conditions. +You may not impose any further restrictions on the recipients' exercise of +the rights granted herein. You are not responsible for enforcing compliance +by third parties to this License. + +7. If, as a consequence of a court judgment or allegation of patent infringement +or for any other reason (not limited to patent issues), conditions are imposed +on you (whether by court order, agreement or otherwise) that contradict the +conditions of this License, they do not excuse you from the conditions of +this License. If you cannot distribute so as to satisfy simultaneously your +obligations under this License and any other pertinent obligations, then as +a consequence you may not distribute the Program at all. For example, if a +patent license would not permit royalty-free redistribution of the Program +by all those who receive copies directly or indirectly through you, then the +only way you could satisfy both it and this License would be to refrain entirely +from distribution of the Program. + +If any portion of this section is held invalid or unenforceable under any +particular circumstance, the balance of the section is intended to apply and +the section as a whole is intended to apply in other circumstances. + +It is not the purpose of this section to induce you to infringe any patents +or other property right claims or to contest validity of any such claims; +this section has the sole purpose of protecting the integrity of the free +software distribution system, which is implemented by public license practices. +Many people have made generous contributions to the wide range of software +distributed through that system in reliance on consistent application of that +system; it is up to the author/donor to decide if he or she is willing to +distribute software through any other system and a licensee cannot impose +that choice. + +This section is intended to make thoroughly clear what is believed to be a +consequence of the rest of this License. + +8. If the distribution and/or use of the Program is restricted in certain +countries either by patents or by copyrighted interfaces, the original copyright +holder who places the Program under this License may add an explicit geographical +distribution limitation excluding those countries, so that distribution is +permitted only in or among countries not thus excluded. In such case, this +License incorporates the limitation as if written in the body of this License. + +9. The Free Software Foundation may publish revised and/or new versions of +the General Public License from time to time. Such new versions will be similar +in spirit to the present version, but may differ in detail to address new +problems or concerns. + +Each version is given a distinguishing version number. If the Program specifies +a version number of this License which applies to it and "any later version", +you have the option of following the terms and conditions either of that version +or of any later version published by the Free Software Foundation. If the +Program does not specify a version number of this License, you may choose +any version ever published by the Free Software Foundation. + +10. If you wish to incorporate parts of the Program into other free programs +whose distribution conditions are different, write to the author to ask for +permission. For software which is copyrighted by the Free Software Foundation, +write to the Free Software Foundation; we sometimes make exceptions for this. +Our decision will be guided by the two goals of preserving the free status +of all derivatives of our free software and of promoting the sharing and reuse +of software generally. + + NO WARRANTY + +11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR +THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE +STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM +"AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, +BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS +FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE +OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME +THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. + +12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING +WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE +THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY +GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE +OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA +OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES +OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH +HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. +END OF TERMS AND CONDITIONS + +How to Apply These Terms to Your New Programs + +If you develop a new program, and you want it to be of the greatest possible +use to the public, the best way to achieve this is to make it free software +which everyone can redistribute and change under these terms. + +To do so, attach the following notices to the program. It is safest to attach +them to the start of each source file to most effectively convey the exclusion +of warranty; and each file should have at least the "copyright" line and a +pointer to where the full notice is found. + +<one line to give the program's name and an idea of what it does.> + +Copyright (C) <yyyy> <name of author> + +This program is free software; you can redistribute it and/or modify it under +the terms of the GNU General Public License as published by the Free Software +Foundation; either version 2 of the License, or (at your option) any later +version. + +This program is distributed in the hope that it will be useful, but WITHOUT +ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS +FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. + +You should have received a copy of the GNU General Public License along with +this program; if not, write to the Free Software Foundation, Inc., 51 Franklin +Street, Fifth Floor, Boston, MA 02110-1301, USA. + +Also add information on how to contact you by electronic and paper mail. + +If the program is interactive, make it output a short notice like this when +it starts in an interactive mode: + +Gnomovision version 69, Copyright (C) year name of author Gnomovision comes +with ABSOLUTELY NO WARRANTY; for details type `show w'. This is free software, +and you are welcome to redistribute it under certain conditions; type `show +c' for details. + +The hypothetical commands `show w' and `show c' should show the appropriate +parts of the General Public License. Of course, the commands you use may be +called something other than `show w' and `show c'; they could even be mouse-clicks +or menu items--whatever suits your program. + +You should also get your employer (if you work as a programmer) or your school, +if any, to sign a "copyright disclaimer" for the program, if necessary. Here +is a sample; alter the names: + +Yoyodyne, Inc., hereby disclaims all copyright interest in the program `Gnomovision' +(which makes passes at compilers) written by James Hacker. + +<signature of Ty Coon>, 1 April 1989 Ty Coon, President of Vice This General +Public License does not permit incorporating your program into proprietary +programs. If your program is a subroutine library, you may consider it more +useful to permit linking proprietary applications with the library. If this +is what you want to do, use the GNU Lesser General Public License instead +of this License. diff --git a/Makefile b/Makefile index ff52ac4..9e6c8aa 100644 --- a/Makefile +++ b/Makefile @@ -1,21 +1,7 @@ +# SPDX-FileCopyrightText: 2019 Alyssa Ross <hi(a)alyssa.is> # SPDX-License-Identifier: GPL-2.0-or-later -# Copyright 2019 Alyssa Ross -# -# This program is free software: you can redistribute it and/or modify -# it under the terms of the GNU General Public License as published by -# the Free Software Foundation, either version 2 of the License, or -# (at your option) any later version. -# -# This program is distributed in the hope that it will be useful, -# but WITHOUT ANY WARRANTY; without even the implied warranty of -# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -# GNU General Public License for more details. -# -# You should have received a copy of the GNU General Public License -# along with this program. If not, see <https://www.gnu.org/licenses/>. - -all: mktuntap +all: bindunix mktuntap socketpair .PHONY: all prefix = /usr/local @@ -32,6 +18,8 @@ MKDIR_P = mkdir -p CFLAGS = -g +bindunix socketpair: util.o + install-dirs: $(MKDIR_P) $(DESTDIR)$(bindir) $(DESTDIR)$(man8dir) .PHONY: install-dirs diff --git a/README b/README index 5f19bec..5a62791 100644 --- a/README +++ b/README @@ -1,3 +1,6 @@ +SPDX-FileCopyrightText: 2019-2020 Alyssa Ross <hi(a)alyssa.is> +SPDX-License-Identifier: GPL-2.0-or-later + mktuntap -------- @@ -19,3 +22,6 @@ published by the Free Software Foundation. Other source files are licensed under the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version. + +Some utility files (.gitignore, etc.) are licensed under the CC0 +1.0 Universal Public Domain Dedication. diff --git a/TODO b/TODO index 7a72fe4..a3dd911 100644 --- a/TODO +++ b/TODO @@ -1 +1,4 @@ +SPDX-FileCopyrightText: 2019 Alyssa Ross <hi(a)alyssa.is> +SPDX-License-Identifier: CC0-1.0 + * Reimplement tap_alloc for compatibility with newer GPLs diff --git a/mktuntap.8 b/mktuntap.8 index 9bbfb78..0f9aaf8 100644 --- a/mktuntap.8 +++ b/mktuntap.8 @@ -1,19 +1,5 @@ +.\" SPDX-FileCopyrightText: 2019 Alyssa Ross <hi(a)alyssa.is> .\" SPDX-License-Identifier: GPL-2.0-or-later -.\" -.\" Copyright 2019 Alyssa Ross -.\" -.\" This program is free software: you can redistribute it and/or modify -.\" it under the terms of the GNU General Public License as published by -.\" the Free Software Foundation, either version 2 of the License, or -.\" (at your option) any later version. -.\" -.\" This program is distributed in the hope that it will be useful, -.\" but WITHOUT ANY WARRANTY; without even the implied warranty of -.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -.\" GNU General Public License for more details. -.\" -.\" You should have received a copy of the GNU General Public License -.\" along with this program. If not, see <https://www.gnu.org/licenses/>. .Dd December 15, 2019 .Dt MKTUNTAP 8 .Os Linux diff --git a/mktuntap.c b/mktuntap.c index 53a47de..b150dc7 100644 --- a/mktuntap.c +++ b/mktuntap.c @@ -1,20 +1,6 @@ +// SPDX-FileCopyrightText: 2019 Alyssa Ross <hi(a)alyssa.is> // SPDX-License-Identifier: GPL-2.0-only -/* - * This program is free software; you can redistribute it and/or modify - * it under the terms of version 2 of the GNU General Public License as - * published by the Free Software Foundation. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA - */ - #include <errno.h> #include <fcntl.h> #include <limits.h> @@ -116,7 +102,7 @@ int main(int argc, char **argv) char *target_fd_end; long int target_fd_l = strtol(argv[optind], &target_fd_end, 10); if (errno) { - fprintf(stderr, "mktuntap: %s\n", strerror(errno)); + perror("mktuntap"); return EX_USAGE; } if (argv[optind][0] == '\0' || target_fd_end[0] != '\0') { @@ -139,30 +125,30 @@ int main(int argc, char **argv) ifr_flags_ |= IFF_VNET_HDR; int tuntap_fd = tuntap_alloc(ifr_name_, open_flags, ifr_flags_); if (tuntap_fd < 0) { - fprintf(stderr, "mktuntap: failed to open tuntap device: %s\n", strerror(errno)); + perror("mktuntap: failed to open tuntap device"); return EX_IOERR; } if (tuntap_fd != target_fd) { if (dup2(tuntap_fd, target_fd) == -1) { - fprintf(stderr, "mktuntap: %s\n", strerror(errno)); + perror("mktuntap"); return EX_IOERR; } if (close(tuntap_fd) == -1) { - fprintf(stderr, "mktuntap: %s\n", strerror(errno)); + perror("mktuntap"); return EX_IOERR; } } if (name_env) { if (setenv("TUNTAP_NAME", ifr_name_, 1) == -1) { - fprintf(stderr, "mktuntap: %s\n", strerror(errno)); + perror("mktunap"); return EX_OSERR; } } execvp(argv[optind + 1], &argv[optind + 1]); - fprintf(stderr, "failed to exec: %s\n", strerror(errno)); + perror("failed to exec"); return EX_OSERR; } -- 2.27.0

2 3

[PATCH wayland] Support virtio_wl display sockets
by Alyssa Ross 27 Jul '20

27 Jul '20

This patch adds libvirtio_wl, which exposes reimplementations of the sendmsg(2) and recvmsg(2) for virtio_wl socket fds. Tests for as much libvirtio_wl functionality as is reasonably possible to test without requiring a working virtio_wl connection are included. (Testing further would require running tests in a VM so that they could talk to the virtio_wl kernel driver, which would be prohibitively complex. virtio_wl socket fds do not actually point to sockets, but to special virtio_wl files. Whenever a display socket operation calls sendmsg() or recvmsg() with a file descriptor and receives an ENOTSOCK error, it retries the operation with the equivalent libvirtio_wl function, in case the file descriptor is a virtio_wl. This is the least invasive way to implement virtio_wl support -- if a normal socket is being used, there will be no change in behaviour. Because virtio_wl doesn't implement every socket feature, some workarounds are currently required to accomodate everything Wayland expects of sockets: * virtio_wl_recvmsg implements the MSG_DONTWAIT flag by setting O_NONBLOCK on the fd, attempting the VIRTWL_IOCTL_RECV operation, and then restoring the fd's original flags. This is obviously race-prone, but there is no reasonable alternative at present. * virtio_wl_sendmsg requires MSG_NOSIGNAL to be set, and ignores it. This is because I think from looking at the code that virtio_wl does not generate SIGPIPE signals, nor does it ever return EPIPE. I could be wrong about this, though. * virtio_wl does not support credential passing -- what would it even mean, considering the other end of the connection is on another (virtual) machine? So wl_client's ucred member will have pid, uid, and gid all set to -1 for a client connected over virtio_wl. * virtio_wl sockets do not support accept(2), so a fallback is used. A proxy program on the host accept(2) on a host socket. When it receives a connection, it attaches the connection socket to the VM, then sends the name of the connected socket over the Wayland display socket. Wayland then receives this name, looks up the connection socket, and uses that as the client connection socket. Additionally, virtio_wl memfd-like file descriptors don't support mremap(2), so for virtio_wl sockets Wayland will munmap(2) the memfd, and then mmap(2) it again. This should be at least mostly okay because Wayland only ever calls mremap with MREMAP_MAYMOVE, but it is still race-prone. To be able to do this, memfds are no longer closed after being mmaped, but are kept around in the wl_shm_pool struct, so that they can be passed to mmap() if required. --- src/connection.c | 4 + src/meson.build | 16 +- src/virtio_wl.c | 344 +++++++++++++++++++++++ src/virtio_wl.h | 23 ++ src/wayland-os.c | 23 ++ src/wayland-os.h | 3 + src/wayland-server.c | 20 +- src/wayland-shm.c | 24 +- tests/meson.build | 1 + tests/virtio_wl-test.c | 615 +++++++++++++++++++++++++++++++++++++++++ 10 files changed, 1064 insertions(+), 9 deletions(-) create mode 100644 src/virtio_wl.c create mode 100644 src/virtio_wl.h create mode 100644 tests/virtio_wl-test.c diff --git a/src/connection.c b/src/connection.c index d0c7d9f..1bfbd8c 100644 --- a/src/connection.c +++ b/src/connection.c @@ -40,6 +40,7 @@ #include <time.h> #include <ffi.h> +#include "virtio_wl.h" #include "wayland-util.h" #include "wayland-private.h" #include "wayland-os.h" @@ -314,6 +315,9 @@ wl_connection_flush(struct wl_connection *connection) do { len = sendmsg(connection->fd, &msg, MSG_NOSIGNAL | MSG_DONTWAIT); + if (len == -1 && errno == ENOTSOCK) + len = virtio_wl_sendmsg(connection->fd, &msg, + MSG_NOSIGNAL | MSG_DONTWAIT); } while (len == -1 && errno == EINTR); if (len == -1) diff --git a/src/meson.build b/src/meson.build index 2d1485c..cca1d93 100644 --- a/src/meson.build +++ b/src/meson.build @@ -71,13 +71,26 @@ if get_option('libraries') mathlib_dep = cc.find_library('m', required: false) threads_dep = dependency('threads', required: false) + virtio_wl = library( + 'virtio_wl', + sources: [ + 'virtio_wl.c', + ], + version: '0.1.0', + install: true, + ) + + virtio_wl_dep = declare_dependency( + link_with: virtio_wl, + ) + wayland_private = static_library( 'wayland-private', sources: [ 'connection.c', 'wayland-os.c' ], - dependencies: [ ffi_dep, ] + dependencies: [ ffi_dep, virtio_wl_dep ] ) wayland_private_dep = declare_dependency( @@ -230,5 +243,6 @@ if get_option('libraries') 'wayland-server-core.h', 'wayland-client.h', 'wayland-client-core.h', + 'virtio_wl.h', ]) endif diff --git a/src/virtio_wl.c b/src/virtio_wl.c new file mode 100644 index 0000000..a1ee8ee --- /dev/null +++ b/src/virtio_wl.c @@ -0,0 +1,344 @@ +/* Copyright 2020 Alyssa Ross + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at https://mozilla.org/MPL/2.0/. */ + +#define _POSIX_C_SOURCE 200809L + +#include <errno.h> +#include <fcntl.h> +#include <limits.h> +#include <linux/virtwl.h> +#include <stdint.h> +#include <stdlib.h> +#include <string.h> +#include <sys/ioctl.h> +#include <sys/socket.h> +#include <unistd.h> + +#include "virtio_wl.h" + +// This is essentially vendored reusable library code, so I consider +// it exempt from the Wayland style guide. :) + +#if defined(__GNUC__) && __GNUC__ >= 4 +#define VIRTIO_WL_EXPORT __attribute__ ((visibility("default"))) +#else +#define VIRTIO_WL_EXPORT +#endif + +static int +set_nonblocking(int fd) +{ + int fl = fcntl(fd, F_GETFL); + if (fl == -1) + return -1; + if (!(fl & O_NONBLOCK)) + if (fcntl(fd, F_SETFL, fl | O_NONBLOCK) == -1) + return -1; + return fl; +} + +// Returns the total size of all buffers in an iovec. +// A return value of -1 means that the total overflowed. +static ssize_t +iov_len(const struct iovec iov[], size_t n) +{ + size_t len = 0; + for (size_t i = 0; i < n; i++) { + if (SSIZE_MAX - len < iov[i].iov_len) + return -1; + len += iov[i].iov_len; + } + return len; +} + +// Copies from an iovec array into a buffer. +// The buffer is assumed to be large enough to hold all the data. +// This length can be calculated with the iov_len function. +static size_t +iov_flatten(void *buf, size_t buflen, const struct iovec *iov, size_t iovlen) +{ + size_t off = 0; + + for (size_t index = 0; index < iovlen && off < buflen; index++) { + const struct iovec *i = &iov[index]; + size_t rem = buflen - off; + size_t len = i->iov_len < rem ? i->iov_len : rem; + + memcpy((unsigned char *)buf + off, i->iov_base, len); + off += len; + } + + return off; +} + +// Copies from a buffer into an iovec array. +// Returns number of bytes copied. +static size_t +iov_fill(struct iovec *iov, size_t iovlen, const void *buf, size_t buflen) +{ + size_t off = 0; + + for (size_t index = 0; index < iovlen && off < buflen; index++) { + struct iovec *i = &iov[index]; + size_t rem = buflen - off; + size_t len = i->iov_len < rem ? i->iov_len : rem; + + memcpy(i->iov_base, (const unsigned char *)buf + off, len); + off += len; + } + + return off; +} + +static ssize_t +cmsg_to_fdbuf(int *buf, size_t buflen, const struct msghdr *msg) +{ + size_t next_fd = 0; + + for (struct cmsghdr *cmsg = CMSG_FIRSTHDR(msg); + cmsg != NULL; cmsg = CMSG_NXTHDR(msg, cmsg)) { + size_t size = cmsg->cmsg_len - CMSG_LEN(0); + + // Check the cmsg can be handled. + if (cmsg->cmsg_level != SOL_SOCKET || + cmsg->cmsg_type != SCM_RIGHTS || + size % sizeof(int) != 0) { + errno = EINVAL; + return -1; + } + + size_t rem = sizeof(int) * (buflen - next_fd); + size_t len = size > rem ? rem : size; + + // Copy the fds to the buffer. + memcpy(buf + next_fd, CMSG_DATA(cmsg), len); + next_fd += len / sizeof(int); + + if (size > rem) + break; + } + + return next_fd > SSIZE_MAX ? SSIZE_MAX : next_fd; +} + +static size_t +fdbuf_to_cmsg(struct msghdr *msg, const int *buf, size_t buflen) +{ + // Check msg->msg_control is long enough to fit at least one fd. + if (msg->msg_controllen < CMSG_SPACE(sizeof(int))) { + + // If there's at least one fd in buf, set MSG_CTRUNC. + size_t i = 0; + while (i < buflen && !(msg->msg_flags & MSG_CTRUNC)) + if (buf[i++] != -1) + msg->msg_flags |= MSG_CTRUNC; + + return 0; + } + + // cmsg(3): + // > When initializing a buffer that will contain a series of cmsghdr + // > structures (e.g., to be sent with sendmsg(2)), that buffer should + // > first be zero-initialized to en‐ sure the correct operation of + // > CMSG_NXTHDR(). + memset(msg->msg_control, 0, msg->msg_controllen); + + // Set up the cmsg. + struct cmsghdr *cmsg = CMSG_FIRSTHDR(msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + + // Copy as many fds as fit into cmsg. + size_t len = 0; + for (size_t i = 0; i < buflen; i++) { + if (buf[i] == -1) + continue; + + if (CMSG_LEN((len + 1) * sizeof(int)) > msg->msg_controllen) { + msg->msg_flags |= MSG_CTRUNC; + break; + } + + memcpy(CMSG_DATA(cmsg) + sizeof(int) * len, &buf[i], sizeof(int)); + len++; + } + + cmsg->cmsg_len = CMSG_LEN(len * sizeof(int)); + return len; +} + +VIRTIO_WL_EXPORT int +virtio_wl_connect(const char *name, uint32_t flags) +{ + static int wl_fd = -1; + if (wl_fd < 0) + wl_fd = open("/dev/wl0", O_RDWR | O_CLOEXEC); + if (wl_fd < 0) + return wl_fd; + + struct virtwl_ioctl_new new_ctx = { + .type = name ? VIRTWL_IOCTL_NEW_CTX_NAMED : VIRTWL_IOCTL_NEW_CTX, + .fd = -1, + .flags = flags, + }; + // Device assumes name 32 bytes long if not null terminated. + if (name) + strncpy(new_ctx.name, name, sizeof(new_ctx.name)); + + if (ioctl(wl_fd, VIRTWL_IOCTL_NEW, &new_ctx)) + return -1; + + return new_ctx.fd; +} + +VIRTIO_WL_EXPORT int +virtio_wl_send_raw(int sockfd, struct virtwl_ioctl_txn *ioctl_txn) +{ + return ioctl(sockfd, VIRTWL_IOCTL_SEND, ioctl_txn); +} + +static int +msghdr_to_txn(const struct msghdr *msg, struct virtwl_ioctl_txn **txn) +{ + // Make sure that if there's an error and the caller tries to free *txn + // anyway it doesn't end up freeing an invalid address. + *txn = NULL; + + // Figure out how big the txn needs to be. + ssize_t len = iov_len(msg->msg_iov, msg->msg_iovlen); + if (len < 0 || len > UINT32_MAX) { + errno = ENOMEM; + return -1; + } + + // Allocate the txn. + *txn = malloc(sizeof(**txn) + len); + if (!*txn) + return -1; + + // Set the len member of the txn. + (*txn)->len = len; + + // Copy data from the iovec into the transaction. + iov_flatten((*txn)->data, len, msg->msg_iov, msg->msg_iovlen); + + // Copy file descriptors to the txn. + ssize_t fd_count = cmsg_to_fdbuf((*txn)->fds, VIRTWL_SEND_MAX_ALLOCS, msg); + if (fd_count == -1) { + free(*txn); + *txn = NULL; + return -1; + } + + // Fill the rest of the fd buffer with -1. + while (fd_count < VIRTWL_SEND_MAX_ALLOCS) + (*txn)->fds[fd_count++] = -1; + + return 0; +} + +static void +txn_to_msghdr(struct msghdr *msg, const struct virtwl_ioctl_txn *txn) +{ + // Copy txn data to iovecs. + iov_fill(msg->msg_iov, msg->msg_iovlen, txn->data, txn->len); + + // Copy fds to cmsg. + fdbuf_to_cmsg(msg, txn->fds, VIRTWL_SEND_MAX_ALLOCS); +} + +VIRTIO_WL_EXPORT ssize_t +virtio_wl_sendmsg(int sockfd, const struct msghdr *msg, int flags) +{ + int sockfl; + + if ((flags & ~MSG_DONTWAIT) != MSG_NOSIGNAL) { + errno = EINVAL; + return -1; + } + + struct virtwl_ioctl_txn *txn; + if (msghdr_to_txn(msg, &txn) == -1) + return -1; + + if (flags & MSG_DONTWAIT) { + sockfl = set_nonblocking(sockfd); + if (sockfl == -1) { + free(txn); + return -1; + } + } + + int rv = virtio_wl_send_raw(sockfd, txn); + + if ((flags & MSG_DONTWAIT) && !(sockfl & O_NONBLOCK)) { + if (fcntl(sockfd, F_SETFL, sockfl) == -1) { + free(txn); + return -1; + } + } + + if (rv != -1) + rv = txn->len; + + free(txn); + return rv; +} + +VIRTIO_WL_EXPORT int +virtio_wl_recv_raw(int sockfd, struct virtwl_ioctl_txn *ioctl_txn) +{ + return ioctl(sockfd, VIRTWL_IOCTL_RECV, ioctl_txn); +} + +VIRTIO_WL_EXPORT ssize_t +virtio_wl_recvmsg(int sockfd, struct msghdr *msg, int flags) +{ + int sockfl; + + if ((flags & ~MSG_DONTWAIT) != MSG_CMSG_CLOEXEC) { + errno = EINVAL; + return -1; + } + + ssize_t len = iov_len(msg->msg_iov, msg->msg_iovlen); + if (len < 0 || len > UINT32_MAX) { + errno = ENOMEM; + return -1; + } + + struct virtwl_ioctl_txn *txn = malloc(sizeof(*txn) + len); + if (!txn) + return -1; + + txn->len = len; + + if (flags & MSG_DONTWAIT) { + sockfl = set_nonblocking(sockfd); + if (sockfl == -1) { + free(txn); + return -1; + } + } + + ssize_t rv = virtio_wl_recv_raw(sockfd, txn); + + if ((flags & MSG_DONTWAIT) && !(sockfl & O_NONBLOCK)) + if (fcntl(sockfd, F_SETFL, sockfl) == -1) + rv = -1; + + if (rv == -1) { + for (size_t i = 0; i < VIRTWL_SEND_MAX_ALLOCS; i++) + if (txn->fds[i] == -1) + close(txn->fds[i]); + } else { + txn_to_msghdr(msg, txn); + rv = txn->len; + } + + free(txn); + return rv; +} diff --git a/src/virtio_wl.h b/src/virtio_wl.h new file mode 100644 index 0000000..80bcd38 --- /dev/null +++ b/src/virtio_wl.h @@ -0,0 +1,23 @@ +/* Copyright 2020 Alyssa Ross + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at https://mozilla.org/MPL/2.0/. */ + +#ifndef UTIL_VIRTIO_WL_H +#define UTIL_VIRTIO_WL_H + +#include <sys/types.h> + +struct virtwl_ioctl_txn; +struct msghdr; + +int virtio_wl_connect(const char *name, uint32_t flags); + +ssize_t virtio_wl_sendmsg(int sockfd, const struct msghdr *, int flags); +int virtio_wl_send_raw(int sockfd, struct virtwl_ioctl_txn *); + +ssize_t virtio_wl_recvmsg(int sockfd, struct msghdr *, int flags); +int virtio_wl_recv_raw(int sockfd, struct virtwl_ioctl_txn *); + +#endif diff --git a/src/wayland-os.c b/src/wayland-os.c index 93b6f5f..c92aaae 100644 --- a/src/wayland-os.c +++ b/src/wayland-os.c @@ -31,6 +31,9 @@ #include <fcntl.h> #include <errno.h> #include <sys/epoll.h> +#include <virtio_wl.h> +#include <string.h> +#include <stdio.h> #include "../config.h" #include "wayland-os.h" @@ -126,6 +129,10 @@ wl_os_recvmsg_cloexec(int sockfd, struct msghdr *msg, int flags) len = recvmsg(sockfd, msg, flags | MSG_CMSG_CLOEXEC); if (len >= 0) return len; + + if (errno == ENOTSOCK) + return virtio_wl_recvmsg(sockfd, msg, flags | MSG_CMSG_CLOEXEC); + if (errno != EINVAL) return -1; @@ -165,3 +172,19 @@ wl_os_accept_cloexec(int sockfd, struct sockaddr *addr, socklen_t *addrlen) fd = accept(sockfd, addr, addrlen); return set_cloexec_or_close(fd); } + +int +wl_virtio_accept_cloexec(int sockfd) +{ + char name[32]; + size_t offset = 0; + + while (offset < sizeof name) { + ssize_t size = read(sockfd, name + offset, sizeof name - offset); + if (size < 0) + return size; + offset += size; + } + + return virtio_wl_connect(name, 0); +} diff --git a/src/wayland-os.h b/src/wayland-os.h index f51efaa..899ac8e 100644 --- a/src/wayland-os.h +++ b/src/wayland-os.h @@ -41,6 +41,9 @@ wl_os_epoll_create_cloexec(void); int wl_os_accept_cloexec(int sockfd, struct sockaddr *addr, socklen_t *addrlen); +int +wl_virtio_accept_cloexec(int sockfd); + /* * The following are for wayland-os.c and the unit tests. diff --git a/src/wayland-server.c b/src/wayland-server.c index 3f48dfe..0146ca8 100644 --- a/src/wayland-server.c +++ b/src/wayland-server.c @@ -531,8 +531,18 @@ wl_client_create(struct wl_display *display, int fd) len = sizeof client->ucred; if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, - &client->ucred, &len) < 0) - goto err_source; + &client->ucred, &len) < 0 && errno != ENOTSOCK) { + if (errno == ENOTSOCK) { + // Probably a virtio_wl socket. + // We don't have credential information, so fill with + // values that should never match real ones. + client->ucred.pid = -1; + client->ucred.uid = -1; + client->ucred.gid = -1; + } else { + goto err_source; + } + } client->connection = wl_connection_create(fd); if (client->connection == NULL) @@ -1419,6 +1429,9 @@ socket_data(int fd, uint32_t mask, void *data) length = sizeof name; client_fd = wl_os_accept_cloexec(fd, (struct sockaddr *) &name, &length); + if (client_fd < 0 && errno == ENOTSOCK) + client_fd = wl_virtio_accept_cloexec(fd); + if (client_fd < 0) wl_log("failed to accept: %s\n", strerror(errno)); else @@ -1603,7 +1616,8 @@ wl_display_add_socket_fd(struct wl_display *display, int sock_fd) struct stat buf; /* Require a valid fd or fail */ - if (sock_fd < 0 || fstat(sock_fd, &buf) < 0 || !S_ISSOCK(buf.st_mode)) { + if (sock_fd < 0 || fstat(sock_fd, &buf) < 0 || + ((buf.st_mode & S_IFMT) && !S_ISSOCK(buf.st_mode))) { return -1; } diff --git a/src/wayland-shm.c b/src/wayland-shm.c index b85e5a7..636ee7a 100644 --- a/src/wayland-shm.c +++ b/src/wayland-shm.c @@ -61,6 +61,7 @@ struct wl_shm_pool { int internal_refcount; int external_refcount; char *data; + int fd; int32_t size; int32_t new_size; bool sigbus_is_impossible; @@ -91,14 +92,27 @@ shm_pool_finish_resize(struct wl_shm_pool *pool) data = mremap(pool->data, pool->size, pool->new_size, MREMAP_MAYMOVE); if (data == MAP_FAILED) { - wl_resource_post_error(pool->resource, - WL_SHM_ERROR_INVALID_FD, - "failed mremap"); - return; + if (errno != EFAULT) + goto fail; + + if (munmap(pool->data, pool->size) == -1) + goto fail; + + data = mmap(pool->data, pool->new_size, PROT_READ | PROT_WRITE, + MAP_SHARED, pool->fd, 0); + if (data == MAP_FAILED) + goto fail; } pool->data = data; pool->size = pool->new_size; + + return; + + fail: + wl_resource_post_error(pool->resource, + WL_SHM_ERROR_INVALID_FD, + "failed mremap"); } static void @@ -291,6 +305,7 @@ shm_create_pool(struct wl_client *client, struct wl_resource *resource, pool->external_refcount = 0; pool->size = size; pool->new_size = size; + pool->fd = fd; pool->data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (pool->data == MAP_FAILED) { @@ -300,7 +315,6 @@ shm_create_pool(struct wl_client *client, struct wl_resource *resource, strerror(errno)); goto err_free; } - close(fd); pool->resource = wl_resource_create(client, &wl_shm_pool_interface, 1, id); diff --git a/tests/meson.build b/tests/meson.build index 224f48d..6ee2b49 100644 --- a/tests/meson.build +++ b/tests/meson.build @@ -148,6 +148,7 @@ tests = { 'headers-protocol-core-test.c', ], 'os-wrappers-test': [], + 'virtio_wl-test': [], } foreach test_name, test_extra_sources: tests diff --git a/tests/virtio_wl-test.c b/tests/virtio_wl-test.c new file mode 100644 index 0000000..16c7a93 --- /dev/null +++ b/tests/virtio_wl-test.c @@ -0,0 +1,615 @@ +#define _GNU_SOURCE +#include <assert.h> + +#include "test-runner.h" +#include "virtio_wl.c" + +TEST(iov_len_fit) +{ + int f1[] = { 1, 2 }; + int f2[] = { 3 }; + + struct iovec iov[] = { + { .iov_base = f1, .iov_len = sizeof(f1) }, + { .iov_base = NULL, .iov_len = 0 }, + { .iov_base = f2, .iov_len = sizeof(f2) }, + }; + + assert(iov_len(iov, sizeof(iov) / sizeof(*iov)) == 3 * sizeof(int)); +} + +TEST(iov_len_overflow) +{ + struct iovec iov[] = { + { .iov_base = NULL, .iov_len = SIZE_MAX }, + { .iov_base = NULL, .iov_len = SIZE_MAX }, + }; + + assert(iov_len(iov, sizeof(iov) / sizeof(*iov)) == -1); +} + +TEST(iov_flatten_test) +{ + int f1[] = { 1 }; + int f2[] = { 2, 3 }; + + struct iovec iov[] = { + { .iov_base = f1, .iov_len = sizeof(f1) }, + { .iov_base = NULL, .iov_len = 0 }, + { .iov_base = f2, .iov_len = sizeof(f2) }, + }; + + int buf[2]; + iov_flatten(buf, sizeof(buf), iov, sizeof(iov) / sizeof(*iov)); + assert(buf[0] == 1); + assert(buf[1] == 2); +} + +TEST(iov_flatten_zero_iov) +{ + unsigned char buf[] = { 0xFF }; + assert(iov_flatten(buf, 1, NULL, 0) == 0); +} + +TEST(iov_flatten_null_iov) +{ + unsigned char buf[] = { 0xFF }; + struct iovec iov[] = { { .iov_base = NULL, .iov_len = 0 } }; + + assert(iov_flatten(buf, sizeof buf, iov, sizeof(iov) / sizeof(*iov)) == 0); +} + +TEST(iov_flatten_zero_buf) +{ + unsigned char f1[] = { 0 }; + struct iovec iov[] = { { .iov_base = f1, .iov_len = sizeof f1 } }; + + assert(iov_flatten(NULL, 0, iov, sizeof(iov) / sizeof(*iov)) == 0); +} + +TEST(iov_flatten_short_iov) +{ + int f1[] = { 1 }; + int f2[] = { 2, 3 }; + + struct iovec iov[] = { + { .iov_base = f1, .iov_len = sizeof f1 }, + { .iov_base = NULL, .iov_len = 0 }, + { .iov_base = f2, .iov_len = sizeof f2 }, + }; + + int buf[] = { 9, 8, 7, 6 }; + + assert(iov_flatten(buf, sizeof buf, iov, sizeof(iov) / sizeof(*iov)) == 12); + assert(buf[0] == 1); + assert(buf[1] == 2); + assert(buf[2] == 3); + assert(buf[3] == 6); +} + +TEST(iov_flatten_exact_iov) +{ + int f1[] = { 1 }; + int f2[] = { 2, 3 }; + + struct iovec iov[] = { + { .iov_base = f1, .iov_len = sizeof f1 }, + { .iov_base = NULL, .iov_len = 0 }, + { .iov_base = f2, .iov_len = sizeof f2 }, + }; + + int buf[] = { 9, 8, 7 }; + + assert(iov_flatten(buf, sizeof buf, iov, sizeof(iov) / sizeof(*iov)) == 12); + assert(f1[0] == 1); + assert(f2[0] == 2); + assert(f2[1] == 3); +} + +TEST(iov_flatten_long_iov) +{ + int f1[] = { 1 }; + int f2[] = { 2, 3, 4 }; + + struct iovec iov[] = { + { .iov_base = f1, .iov_len = sizeof f1 }, + { .iov_base = NULL, .iov_len = 0 }, + { .iov_base = f2, .iov_len = sizeof f2 }, + }; + + int buf[] = { 9, 8, 7 }; + + assert(iov_flatten(buf, sizeof buf, iov, sizeof(iov) / sizeof(*iov)) == 12); + assert(buf[0] == 1); + assert(buf[1] == 2); + assert(buf[2] == 3); +} + +TEST(iov_fill_zero_iov) +{ + unsigned char buf[] = { 0xFF }; + assert(iov_fill(NULL, 0, buf, 1) == 0); +} + +TEST(iov_fill_null_iov) +{ + unsigned char buf[] = { 0xFF }; + struct iovec iov[] = { { .iov_base = NULL, .iov_len = 0 } }; + + assert(iov_fill(iov, sizeof(iov) / sizeof(*iov), buf, sizeof buf) == 0); +} + +TEST(iov_fill_zero_buf) +{ + unsigned char f1[] = { 0 }; + struct iovec iov[] = { { .iov_base = f1, .iov_len = sizeof f1 } }; + + assert(iov_fill(iov, sizeof(iov) / sizeof(*iov), NULL, 0) == 0); +} + +TEST(iov_fill_short_iov) +{ + int f1[] = { 1 }; + int f2[] = { 2, 3 }; + + struct iovec iov[] = { + { .iov_base = f1, .iov_len = sizeof f1 }, + { .iov_base = NULL, .iov_len = 0 }, + { .iov_base = f2, .iov_len = sizeof f2 }, + }; + + int buf[] = { 9, 8, 7, 6 }; + + assert(iov_fill(iov, sizeof(iov) / sizeof(*iov), buf, sizeof buf) == 12); + assert(f1[0] == 9); + assert(f2[0] == 8); + assert(f2[1] == 7); +} + +TEST(iov_fill_exact) +{ + int f1[] = { 1 }; + int f2[] = { 2, 3 }; + + struct iovec iov[] = { + { .iov_base = f1, .iov_len = sizeof f1 }, + { .iov_base = NULL, .iov_len = 0 }, + { .iov_base = f2, .iov_len = sizeof f2 }, + }; + + int buf[] = { 9, 8, 7 }; + + assert(iov_fill(iov, sizeof(iov) / sizeof(*iov), buf, sizeof buf) == 12); + assert(f1[0] == 9); + assert(f2[0] == 8); + assert(f2[1] == 7); +} + +TEST(iov_fill_long_iov) +{ + int f1[] = { 1 }; + int f2[] = { 2, 3, 4 }; + + struct iovec iov[] = { + { .iov_base = f1, .iov_len = sizeof f1 }, + { .iov_base = NULL, .iov_len = 0 }, + { .iov_base = f2, .iov_len = sizeof f2 }, + }; + + int buf[] = { 9, 8, 7 }; + + assert(iov_fill(iov, sizeof(iov) / sizeof(*iov), buf, sizeof buf) == 12); + assert(f1[0] == 9); + assert(f2[0] == 8); + assert(f2[1] == 7); + assert(f2[2] == 4); +} + +TEST(cmsg_to_fdbuf_zero_buf) +{ + int fds[] = { 0 }; + + union { + char buf[CMSG_SPACE(sizeof fds)]; + struct cmsghdr align; + } u; + + struct msghdr msg = { 0 }; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof fds); + memcpy(CMSG_DATA(cmsg), fds, sizeof fds); + + assert(cmsg_to_fdbuf(NULL, 0, &msg) == 0); +} + +TEST(cmsg_to_fdbuf_zero_cmsg) +{ + int fds[2] = { 0 }; + struct msghdr msg = { 0 }; + assert(cmsg_to_fdbuf(fds, sizeof fds, &msg) == 0); +} + +TEST(cmsg_to_fdbuf_small_buf) +{ + int fds[] = { 0, 1 }; + + union { + char buf[CMSG_SPACE(sizeof fds)]; + struct cmsghdr align; + } u; + + struct msghdr msg = { 0 }; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof fds); + memcpy(CMSG_DATA(cmsg), fds, sizeof fds); + + int buf[] = { 0xFF }; + assert(cmsg_to_fdbuf(buf, sizeof(buf) / sizeof(*buf), &msg) == 1); + assert(buf[0] == 0); +} + +TEST(cmsg_to_fdbuf_exact) +{ + int fds[] = { 0, 1 }; + + union { + char buf[CMSG_SPACE(sizeof fds)]; + struct cmsghdr align; + } u; + + struct msghdr msg = { 0 }; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof fds); + memcpy(CMSG_DATA(cmsg), fds, sizeof fds); + + int buf[] = { 0xFF, 0xFE }; + assert(cmsg_to_fdbuf(buf, sizeof(buf) / sizeof(*buf), &msg) == 2); + assert(buf[0] == 0); + assert(buf[1] == 1); +} + +TEST(cmsg_to_fdbuf_small_cmsg) +{ + int fds[] = { 0 }; + + union { + char buf[CMSG_SPACE(sizeof fds)]; + struct cmsghdr align; + } u; + + struct msghdr msg = { 0 }; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof fds); + memcpy(CMSG_DATA(cmsg), fds, sizeof fds); + + int buf[] = { 0xFF, 0xFE }; + assert(cmsg_to_fdbuf(buf, sizeof(buf) / sizeof(*buf), &msg) == 1); + assert(buf[0] == 0); + assert(buf[1] == 0xFE); +} + +TEST(cmsg_to_fdbuf_multiple_cmsg) +{ + int f1[] = { 0 }; + int f2[] = { 1 }; + + union { + char buf[CMSG_SPACE(sizeof f1) + CMSG_SPACE(sizeof f2)]; + struct cmsghdr align; + } u; + + struct msghdr msg = { 0 }; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + struct cmsghdr *cmsg1 = CMSG_FIRSTHDR(&msg); + cmsg1->cmsg_level = SOL_SOCKET; + cmsg1->cmsg_type = SCM_RIGHTS; + cmsg1->cmsg_len = CMSG_LEN(sizeof f1); + memcpy(CMSG_DATA(cmsg1), f1, sizeof f1); + + struct cmsghdr *cmsg2 = CMSG_NXTHDR(&msg, cmsg1); + cmsg2->cmsg_level = SOL_SOCKET; + cmsg2->cmsg_type = SCM_RIGHTS; + cmsg2->cmsg_len = CMSG_LEN(sizeof f2); + memcpy(CMSG_DATA(cmsg2), f2, sizeof f2); + + int buf[] = { 0xFF, 0xFE }; + assert(cmsg_to_fdbuf(buf, sizeof(buf) / sizeof(*buf), &msg) == 2); + assert(buf[0] == 0); + assert(buf[1] == 1); +} + +TEST(cmsg_to_fdbuf_other_cmsg) +{ + struct ucred cred = { + .pid = getpid(), + .uid = getuid(), + .gid = getgid(), + }; + + int fds[] = { 0, 1 }; + + union { + char buf[CMSG_SPACE(sizeof cred) + CMSG_SPACE(sizeof fds)]; + struct cmsghdr align; + } u; + + struct msghdr msg = { 0 }; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + struct cmsghdr *cmsg1 = CMSG_FIRSTHDR(&msg); + cmsg1->cmsg_level = SOL_SOCKET; + cmsg1->cmsg_type = SCM_CREDENTIALS; + cmsg1->cmsg_len = CMSG_LEN(sizeof cred); + memcpy(CMSG_DATA(cmsg1), &cred, sizeof cred); + + struct cmsghdr *cmsg2 = CMSG_NXTHDR(&msg, cmsg1); + cmsg2->cmsg_level = SOL_SOCKET; + cmsg2->cmsg_type = SCM_RIGHTS; + cmsg2->cmsg_len = CMSG_LEN(sizeof fds); + memcpy(CMSG_DATA(cmsg2), fds, sizeof fds); + + int buf[] = { 0xFF, 0xFE }; + assert(cmsg_to_fdbuf(buf, sizeof(buf) / sizeof(*buf), &msg) == -1); + assert(errno == EINVAL); +} + +TEST(cmsg_to_fdbuf_misaligned) +{ + int fds[] = { 0, 1 }; + + union { + char buf[CMSG_SPACE(sizeof fds + 1)]; + struct cmsghdr align; + } u; + + struct msghdr msg = { 0 }; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(fds) + 1); + memcpy(CMSG_DATA(cmsg), fds, sizeof fds); + CMSG_DATA(cmsg)[sizeof(fds)] = 0; + + int buf[] = { 0xFF, 0xFE }; + assert(cmsg_to_fdbuf(buf, sizeof(buf) / sizeof(*buf), &msg) == -1); + assert(errno == EINVAL); +} + +TEST(fdbuf_to_cmsg_null_cmsg) +{ + struct msghdr msg = { 0 }; + int fds[] = { 1 }; + assert(fdbuf_to_cmsg(&msg, fds, sizeof(fds) / sizeof(*fds)) == 0); + assert(msg.msg_flags & MSG_CTRUNC); +} + +TEST(fdbuf_to_cmsg_empty_both) +{ + struct msghdr msg = { 0 }; + int fds[] = { -1 }; + assert(fdbuf_to_cmsg(&msg, fds, sizeof(fds) / sizeof(*fds)) == 0); + assert(!(msg.msg_flags & MSG_CTRUNC)); +} + +TEST(fdbuf_to_cmsg_null_buf) +{ + union { + char buf[CMSG_SPACE(sizeof(int))]; + struct cmsghdr align; + } u = { 0 }; + + struct msghdr msg = { 0 }; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + assert(fdbuf_to_cmsg(&msg, NULL, 0) == 0); + assert(!(msg.msg_flags & MSG_CTRUNC)); +} + +TEST(fdbuf_to_cmsg_tiny_msg) +{ + union { + char buf[1]; + struct cmsghdr align; + } u = { 0 }; + + struct msghdr msg = { 0 }; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + int fds[] = { 1 }; + assert(fdbuf_to_cmsg(&msg, fds, sizeof(fds) / sizeof(*fds)) == 0); + assert(msg.msg_flags & MSG_CTRUNC); +} + +TEST(fdbuf_to_cmsg_small_msg) +{ + union { + char buf[CMSG_SPACE(sizeof(int))]; + struct cmsghdr align; + } u = { 0 }; + + struct msghdr msg = { 0 }; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + int fds[] = { 1, 2, 3 }; + assert(CMSG_SPACE(sizeof fds) != sizeof u.buf); + + // CMSG_SPACE(sizeof(int)) can equal CMSG_SPACE(sizeof(int) * 2) + size_t n = fdbuf_to_cmsg(&msg, fds, sizeof(fds) / sizeof(*fds)); + assert(CMSG_SPACE(n * sizeof(int)) == sizeof u.buf); + assert(msg.msg_flags & MSG_CTRUNC); +} + +TEST(fdbuf_to_cmsg_equal) +{ + int fds[] = { 1, 2 }; + + union { + char buf[CMSG_SPACE(sizeof fds)]; + struct cmsghdr align; + } u = { 0 }; + + struct msghdr msg = { 0 }; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + assert(fdbuf_to_cmsg(&msg, fds, sizeof(fds) / sizeof(*fds)) == 2); + assert(!memcmp(CMSG_DATA(CMSG_FIRSTHDR(&msg)), fds, sizeof fds)); + assert(!(msg.msg_flags & MSG_CTRUNC)); +} + +TEST(fdbuf_to_cmsg_negative_one) +{ + int fds[] = { 1, -1, -1, 2 }; + + union { + char buf[CMSG_SPACE(2 * sizeof(int))]; + struct cmsghdr align; + } u = { 0 }; + + struct msghdr msg = { 0 }; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + assert(fdbuf_to_cmsg(&msg, fds, sizeof(fds) / sizeof(*fds)) == 2); + + unsigned char *data = CMSG_DATA(CMSG_FIRSTHDR(&msg)); + assert(!memcmp(data, &fds[0], sizeof(int))); + assert(!memcmp(data + sizeof(int), &fds[3], sizeof(int))); + assert(!(msg.msg_flags & MSG_CTRUNC)); +} + +TEST(fdbuf_to_cmsg_small_buf) +{ + int fds[] = { 1 }; + + union { + char buf[CMSG_SPACE(2 * sizeof fds)]; + struct cmsghdr align; + } u = { 0 }; + + struct msghdr msg = { 0 }; + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + assert(fdbuf_to_cmsg(&msg, fds, sizeof(fds) / sizeof(*fds)) == 1); + assert(!memcmp(CMSG_DATA(CMSG_FIRSTHDR(&msg)), fds, sizeof fds)); + assert(!(msg.msg_flags & MSG_CTRUNC)); +} + +TEST(msghdr_to_txn_test) +{ + struct virtwl_ioctl_txn *txn; + + int f1[] = { 1 }; + int f2[] = { 2, 3 }; + + const int fds[] = { 0, 1, 2 }; + + struct iovec iov[] = { + { .iov_base = f1, .iov_len = sizeof f1 }, + { .iov_base = f2, .iov_len = sizeof f2 }, + }; + + union { + char buf[CMSG_SPACE(sizeof fds)]; + struct cmsghdr align; + } u; + + struct msghdr msg = { 0 }; + msg.msg_iov = iov; + msg.msg_iovlen = sizeof(iov) / sizeof(*iov); + msg.msg_control = u.buf; + msg.msg_controllen = sizeof u.buf; + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof fds); + memcpy(CMSG_DATA(cmsg), fds, sizeof fds); + + assert(!msghdr_to_txn(&msg, &txn)); + + assert(txn->len == sizeof(f1) + sizeof(f2)); + assert(!memcmp(txn->fds, fds, sizeof fds)); + for (size_t i = sizeof(fds) / sizeof(*fds); + i < VIRTWL_SEND_MAX_ALLOCS; i++) + assert(txn->fds[i] == -1); + assert(!memcmp(txn->data, f1, sizeof f1)); + assert(!memcmp(txn->data + sizeof f1, f2, sizeof f2)); +} + +TEST(txn_to_msghdr_test) +{ + const int data[] = { 1, 2, 3 }; + + size_t len = sizeof(data); + struct virtwl_ioctl_txn *txn = malloc(sizeof(*txn) + len); + assert(txn); + + txn->len = len; + + const int fds[] = { 0, 1, 2 }; + memcpy(txn->fds, fds, sizeof fds); + for (int i = sizeof(fds) / sizeof(*fds); i < VIRTWL_SEND_MAX_ALLOCS; i++) + txn->fds[i] = -1; + + memcpy(txn->data, data, sizeof data); + + int buf1[1], buf2[2]; + + struct iovec iov[] = { + { .iov_base = buf1, .iov_len = sizeof buf1 }, + { .iov_base = buf2, .iov_len = sizeof buf2 }, + }; + + unsigned char cmsg_buf[VIRTWL_SEND_MAX_ALLOCS]; + + struct msghdr msg = { 0 }; + msg.msg_iov = iov; + msg.msg_iovlen = sizeof(iov) / sizeof(*iov); + msg.msg_control = cmsg_buf; + msg.msg_controllen = sizeof cmsg_buf; + + txn_to_msghdr(&msg, txn); + + assert(!memcmp(buf1, data, sizeof buf1)); + assert(!memcmp(buf2, (unsigned char *)data + sizeof buf1, sizeof buf2)); + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + assert(cmsg->cmsg_level == SOL_SOCKET); + assert(cmsg->cmsg_type == SCM_RIGHTS); + assert(cmsg->cmsg_len == CMSG_LEN(3 * sizeof(int))); + for (int i = 0; i < 3; i++) + assert(!memcmp(CMSG_DATA(cmsg), fds, sizeof fds)); + + assert(!CMSG_NXTHDR(&msg, cmsg)); +} -- 2.26.2

2 4

This Week in Spectrum, 2020-W30
by Alyssa Ross 27 Jul '20

27 Jul '20

Feels like there's a pretty clear path forward. Nice feeling. :) QEMU ---- Last week, as I wrote TWiS, I had just discovered virtio-vhost-user, which looked like a very promising mechanism for getting a VM to take care of networking for other VMs. This week, I've been researching it further, and trying to test and evaluate it. The first thing I tried to do, naturally, was to build the patched QEMU tree and boot a VM with a virtio-vhost-user device attached. This was not as easy as I'd hoped, because adding the virtio-vhost-user device to my QEMU command line made the VM kernel panic at boot, with an error message about an invalid memory access. I spent most of the week trying to figure this out -- I wasn't doing anything different to the example[1] on the QEMU wiki, so it should have worked, and it felt like if I could just get past whatever was going wrong here, it would be worth it, because virtio-vhost-user otherwise seems so suited for what we need here. I emailed the patch author[2], but he didn't know what was up either. An early breakthrough came when I got frustrated with kernel builds taking hours on my 8-year-old laptop, and so decided to work on a more powerful computer instead. Once I got everything set up on that computer, I started up the VM, and it worked. Perhaps in setting it up over here I'd done something different? I copied over the exact VM disk/kernel/initrd/command line that I was running on my laptop, and the other computer booted it just fine. I had -cpu host in the QEMU command line, so I thought maybe the different kind of virtual CPU was causing it. Tried setting it to a specific value on both machines, and still the laptop VM panicked and the other didn't. So it sounded like whether it worked or not depended on the host hardware. I put together a Nix derivation that would automatically build the custom QEMU and output a script that would run a VM, and then asked people in #spectrum to test it out on various computers. After getting some further data, a pattern started to emerge, where Intel processors Ivy Bridge and older would fail, and Skylake and newer would succeed (I didn't encounter any AMD processors that failed, nor did I have data at the time for generations between Ivy Bridge and Skylake). This theory had a convenient explanation for why nobody else had seen this problem -- I doubt people at Red Hat are working on 7-year-old hardware. This was a good clue, but still didn't put me much closer to having a working system. I do have a more recent laptop around, but for reasons that are out of scope here it would be very inconvenient to decide to just move over to it. I could see that the kernel was panicking the first time it tried to access the PCI BARs of the virtio-vhost-user, which led me to believe that the problem was probably in how that memory was being set up. I found the function that did that[3], and stared at it for a long time. I tried to read the rest of the QEMU code, but it became clear that my domain knowledge here isn't good enough to be able to keep track of what's meant to be happening. I added some debug prints, which were vaguely helpful in making that understanding a little better. I was hoping to find the guest address each PCI BAR was mapped to so that I could check the kernel was trying to write to the right location, but didn't manage to do that. While attempting to, though, I did add a debug print that printed the size of each PCI bar as it was allocated. I noticed that most were small -- 16 MiB at most, but one was huge, at 64 GiB! The code that allocated this BAR was part of the function I'd been staring at. As far as I could tell, the choice of size was pretty arbitrary -- this big memory region was used as backing memory for all sorts of small objects on the fly. On a whim, I tried changing the BAR size from 1ULL << 36 to 1ULL << 26, and recompiled QEMU. The VM booted. The comment above the bar_size definition that I'd been looking at for so long said: /* TODO If the BAR is too large the guest won't have address space to map * it! */ I don't know if that's exactly what went wrong here, though. I suspect it's more like the host architecture doesn't have enough address space? The affected machines all reported 36 bit physical address size, and 48 bit virtual address size. So maybe what's happening is that the processor interprets PCI addresses in the hardware-assisted VM as physical addresses, and therefore runs out of space because all of it is taken up by this one PCI bar? I'm not really sure. Lowering the bar size to 2^35 or 2^34 (has to be a power of two) depending on the QEMU version made the problem go away, and that's good enough for now. I'm not very enthusiastic about this up-front allocation of a huge amount of memory that might not even fit in the available address space. I don't know if there's a better way of doing it in this case, but I certainly hope so. In general I think this perhaps demonstrates why this code is not considered suitable for "production" yet. The bet I'm taking here is that by the time Spectrum is further along, things will have moved on for virtio-vhost-user too. As I said, at some point we will want to implement it in crosvm to avoid having QEMU in the TCB, but it would be a bad idea to do that now while virtio-vhost-user is still going through the back-and-forth of making its way into the Virtio spec. [1]: https://wiki.qemu.org/Features/VirtioVhostUser [2]: https://lore.kernel.org/qemu-devel/87h7u1s5k1.fsf@alyssa.is/T/#u [3]: https://github.com/ndragazis/qemu/blob/f9ab08c0c8/hw/virtio/virtio-vhost-us… DPDK ---- Once I was able to boot a VM with the virtio-vhost-user device, I tried to connect another QEMU VM to it through vhost-user -- I'll want to have this working first as a reference before I start porting Cloud Hypervisor's vhost-user implementation to crosvm. But the "frontend" (vhost-user) QEMU process hung waiting for a reply on the vhost-user socket from the backend one. Not really knowing what to do about this, I decided that maybe I'd been a bit too ambitious in going straight for vhost-user <-> virtio-vhost-user when I'd never actually used vhost-user before, so maybe I should try a more conventional vhost-user setup first. As far as I can tell, vhost-user is usually used for connecting a VM to a userspace networking stack. And usually, this networking stack is DPDK, the "Data Plane Development Kit"[4]. DPDK was also used in the virtio-vhost-user examples, so I figured my next step would be to try it there as well, and therefore it was worth the time in learning how to do a very basic setup with it. Quick start -style documentation for this was pretty lacking, but I did eventually manage to make this work. Here's what I did, for my own future reference as much as anything else: (1) Make some hugepages available. 1GiB for DPDK and 1GiB for QEMU: echo 1024 > /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages (2) Take my ethernet interface offline so it could be used with DPDK: nmcli d disconnect enp0s25 (3) Load the vfio-pci module, which allows PCI devices to be exported to userspace rather than managed by the kernel: mobprobe vfio-pci (4) Export the ethernet interface: usertools/dpdk-devbind.py -b vfio-pci enp0s25 (5) Run testpmd, a program that comes with DPDK mostly used for debugging and tracing it seems, but that with no special arguments acts as a simple packet forwarder. Here I create a vhost-user socket, and forward traffic between vhost-user and my ethernet interface: build/app/dpdk-testpmd -l 0,1 -w 00:19.0 \ --vdev net_vhost0,iface=/run/vhost-user0.sock The -w value is the PCI address of the ethernet interface. Note how "00:19" corresponds to "p0s25". (19 in hex is 25 is decimal.) (6) Start a VM. The relevant QEMU flags appear to be: -chardev socket,id=char0,path=/run/vhost-user0.sock \ -netdev type=vhost-user,id=net0,chardev=char0,vhostforce \ -device virtio-net-pci,netdev=net0 \ -object memory-backend-file,id=mem0,size=1024M,mem-path=/dev/hugepages,share=on \ -numa node,memdev=mem0 \ -mem-prealloc I figured this all out mostly from a guide for a DPDK benchmark[5]. I have not yet experimented with variations on the QEMU flags yet. I'm not sure if all the memory flags are required -- -mem-prealloc might just be there because it was important for a benchmark, for example. So this is the point I'm at with this exploration. Next up, I'll be trying with DPDK inside a VM with a virtio-vhost-user device. I think that maybe, despite the virtio-vhost-user device showing up as an ethernet device inside the VM, it needs some special support which is available for DPDK as a patchset, but that has not been written for the kernel yet. I was a bit worried about this, because unlike the kernel, DPDK isn't going to have things that Wi-Fi drivers for all sorts of different hardware, and so using DPDK instead of the kernel network stack would be a problem. But then I learned that DPDK has a component called the Kernel Native Interface (KNI) which allows it to use network interfaces from the kernel, so a hybrid approach would be possible, and is what I think we'll end up using for now. Then, once virtio-vhost-user is a bit more mature, a kernel driver will probably show up, and we can use that instead and drop DPDK. [4]: https://dpdk.org/ [5]: https://doc.dpdk.org/guides/howto/pvp_reference_benchmark.html?highlight=pvp Website ------- I was having a conversation about Spectrum yesterday, and I found myself sending over a bunch of links to articles and papers that I often find myself referring to when talking to somebody about Spectrum. This made me think that maybe there should be some place where we keep all these relevant articles. So I mined the IRC logs, the TWiS archive, and my blog, and added whatever I could pull from my brain, and wrote a Spectrum bibliography, containing 27 links to interesting articles and papers that are particularly relevant to Spectrum. This isn't on the website quite yet, but I did sent this as a patch[6] to the mailing list, if you want an early look. I also posted a patch to fix a minor issue where I'd mistakenly used ".." instead of "." as href values, to no user-visible effect[7]. [6]: https://spectrum-os.org/lists/archives/spectrum-devel/20200726045701.32259-… [7]: https://spectrum-os.org/lists/archives/spectrum-devel/20200726055410.20641-… Documentation ------------- On Monday, I had a call with the Free Software Foundation Europe. They're a part of NGI Zero (where my funding comes from), and they are promoting their new "REUSE" specification[8] for license information in free software projects to NGI Zero projects. It basically covers standardised per-file license and copyright annotations, and a standard way of including license texts. I think this is really cool! It's something I've been unsure of how to handle because it's all vague conventions that are different in different circles, and it's nice to see something formalised about it. They also have an automated tool[9] for checking compliance and semi-automatically adding license information, which is great! So I'm enthusiastically adopting the REUSE specification. I decided that our smaller, first-party repositories (the documentation, the website, etc.) would be a good place to get started, and so I posted a patch[10] that makes the documentation repository REUSE-compliant. [8]: https://reuse.software/ [9]: https://git.fsfe.org/reuse/tool [10]: https://spectrum-os.org/lists/archives/spectrum-devel/20200726105527.27432-… mktuntap -------- I posted a patch[11] to make mktuntap REUSE-compliant. [11]: https://spectrum-os.org/lists/archives/spectrum-devel/20200726110123.30159-… The thing that's most on my mind this week is the extent to which I'm learning about and working on software like QEMU and DPDK that I don't see having a place in Spectrum in the long run. It's counterintuitive, but this is definitely worth it. There's no point writing a kernel driver for virtio-vhost-user (should such a thing be required) right now, because if I use DPDK for now instead, at some point either virtio-vhost-user will end up not being the thing that gets adopted by the ecosystem and we'll have to move to something else, or (more likely) it gets widely adopted and somebody else writes a kernel driver. Similarly, using QEMU for network VMs is the smart choice even though I don't want it to end up in the TCB, because even though I'm probably going to end up implementing virtio-vhost-user in crosvm later, swapping out QEMU is going to be so easy later that it would be a very bad idea to implement that now in case virtio-vhost-user doesn't take off. But it still /feels/ weird to be using QEMU for this stuff, you know?

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This Week in Spectrum, 2020-W29
by Alyssa Ross 20 Jul '20

20 Jul '20

This has been a week of thinking I wanted to do one thing, not being sure how to do it, and finding out that there was a better way. I'll write it up in the order it happened. crosvm ------ Last week, I described that I wanted to implement a virtio proxy to be able to allow a kernel in an application VM to use a virtual device in another VM. I was wondering how to manage virtio buffers, and thought that I probably wanted an allocator to be able to manage throwing buffers of different sizes around. This turned out to be a case of the XY problem[1]. I couldn't find a good solution, but it turned out that an allocator wasn't what I wanted anyway. edef pointed out that I could just make the shared memory I allocated as big as necessary to hold buffers of the maximum size I wanted to support. The kernel will only actually allocate pages as they are written to, and I could use fallocate[2] with FALLOC_FL_PUNCH_HOLE to tell the kernel it can drop pages when I'm done with them. This would mean that an unusually large buffer would only take up lots of memory while it was in use, and as soon as it was done with, the kernel would be able to take back the memory. So exactly what I wanted from an allocator, but with no need for an allocator at all! This made the implementation much simpler, and by Friday I was able to get the proxy into a state where it could pass unit tests that transported messages in both directions through it. And then it was suggested to me that maybe a virtio proxy is not what I want after all. The main disadvantage to a virtio proxy is that it requires context switching to the host to send data between VMs. This is a trade-off I was aware of, but a virtio proxy is pretty straightforward to write as inter-VM communication systems go, and I was not aware of anything else that would be up to the job. As it turns out, there is something. vhost-user is a mechanism for connecting, say, a virtio device to a userspace network stack in a performant way. I was aware of this, but what I was not aware of was virtio-vhost-user[3]. virtio-vhost-user is a proposed mechanism to allow a VMM to forward a vhost-user backend to a VM. This means that two VMs could directly share virtqueues, with no host copy step. This would mean there would be no opportunity for the host to mediate communication between two guests, but that wasn't really on the cards anyway -- if it's ever required, a virtio proxy would probably be the way to go. For all the other cases, virtio-vhost-user would be a faster, cleaner way of sharing network devices between VMs. The main problem with virtio-vhost-user is that it's still in its infancy. There's a patchset[4] implementing it for QEMU that's a couple of years old, but that has not been accepted upstream. The main blocker for this seems to be first standardising it in the Virtio spec[5][6]. The good news here is that the standardisation process seems to be progressing actively at the moment. It's being discussed on the virtio-dev mailing list basically right now, with the most recent emails dated Friday (unfortunately, I don't know of a good web archive with virtio-dev, but you can find the thread on Gmane if you're interested but not subscribed to the list). The good news is that virtio-vhost-user mostly works by composing things that already exist. There's no kernel work required, because devices are just exposed by the VMM as regular virtio devices. The frontend VM (i.e. the one that uses the virtual device, as opposed to the one that provides it) doesn't need any special virtio-vhost-user support, because it just needs to speak normal vhost-user. Only the backend VM needs support for virtio-vhost-user, because its VMM needs to expose the vhost-user backend from the host to that VM. This means that provisionally using virtio-vhost-user in Spectrum actually looks very feasible, with a couple of compromises. For evaluation purposes, it's not worth writing a virtio-vhost-user device for crosvm. But, the VMs that need that device are the ones that are very specialised -- VMs that manage networking or block devices or similar. So for these VMs, for now, we could use QEMU, with the virtio-vhost-user patch. I investigated what it would take to port it to the most recent QEMU version, and the answer appears to be "not much at all". Obviously having two VMMs in the Trusted Computing Base (TCB) isn't something we'd want in the long term, but it would be fine for, say, reaching the next funding milestone. If we decide that virtio-vhost-user is the way to go after all, support in crosvm can be added then -- in general, adding a new virtio device to crosvm isn't a huge undertaking. Earlier, I said that the application side of the communication doesn't need anything special, because to that it's just regular vhost-user. This is true, but I glossed over there that crosvm doesn't actually implement vhost-user. Implementing vhost-user in crosvm would probably be a big deal at this stage, and not something I feel would be a good use of my time. BUT! Remember, crosvm has two children: Amazon's Firecracker[7], and at so-called "serverless" computing; and Intel's Cloud Hypervisor[8], which aims at traditional, full system server virtualisation. And both of these children inherited the crosvm device model from their parents, and Cloud Hypervisor implements vhost-user[9]. So I _think_ it should be possible to pretty much lift the vhost-user implementation from Cloud Hypervisor, and use it in crosvm. Pretty neat! So, the setup I'd like to evaluate is QEMU with the virtio-vhost-user patch on one side, and crosvm with Cloud Hypervisor's vhost-user implementation on the other. It might well be that there are complications here. If there are, I'll probably just finish the proxy and move on for now, because I want to keep up the pace. I do think that virtio-vhost-user is probably the way to do interguest networking in the long-term, though. Another thing that I've realised is that I don't need to worry about pulling bits out of crosvm to run in other VMs. I focused a lot on that towards the beginning of the year, mostly motivated by Wayland, because the virtio wayland implementation in crosvm is the only one there is. Now that that works in a different way, though, there's no need to continue down this path, because things like networking can be done in more normal ways through virtio and the device VM kernel. [1]: https://en.wikipedia.org/wiki/XY_problem [2]: https://man7.org/linux/man-pages/man2/fallocate.2.html [3]: https://wiki.qemu.org/Features/VirtioVhostUser [4]: https://github.com/stefanha/qemu/compare/master...virtio-vhost-user [5]: https://lists.nongnu.org/archive/html/qemu-devel/2019-04/msg03082.html [6]: https://docs.oasis-open.org/virtio/virtio/v1.1/csprd01/virtio-v1.1-csprd01.… [7]: https://firecracker-microvm.github.io/ [8]: https://github.com/cloud-hypervisor/cloud-hypervisor [9]: https://github.com/cloud-hypervisor/cloud-hypervisor/blob/b4d04bdff6a7e2c3d… Overall, it's been frustrating for me to try things, and discover they're not going to work, or not going to work as well as some other thing, and make a call on whether to keep going on something I know is the worse option or switch to the better thing. I have to keep reminding myself that Spectrum is a research project, and there are always going to be false starts like this. Lots of what we're doing is either very unusual (virtio-vhost-user) or brand new (interguest Wayland), after all.

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This Week in Spectrum,
by Alyssa Ross 13 Jul '20

13 Jul '20

After I got an isolated Wayland compositor working last week, I wasn't really sure what to do next -- this was a big piece of work that I'd been very focused on for a while. The funding milestone I'm closest to is to do with implementing hardware isolation, which the Wayland work was a part of, so I decided to keep going with that, and explore other types of isolation. More on that in a bit. Wayland ------- Posted my patch for virtio_wl display socket support in libwayland-server[1]. This is what allows it to run in a VM, and receive connections from clients in other VMs. The patch description is very extensive, so I recommend reading it for more detail if you're interested. It introduces a libvirtio_wl, which should also be useful for porting other programs that we might want to communicate with across a VM boundary, if they are written with normal Unix sockets in mind (including transferring file descriptors). This is the evolution of code I previously had put in wlroots, moved to Wayland for convenience. If it ever acquires another user (or maybe even if it doesn't) it might make sense to make it its own package, since virtio_wl is useful even if Wayland isn't involved. [1]: https://spectrum-os.org/lists/archives/spectrum-devel/SJ0PR03MB5581479F3388… crosvm ------ I pushed all my crosvm changes to get the isolated compositor working to the work-in-progress "interguest" branch[2]. Remember, I only got it working last week right before I needed to start writing the TWiS email, so I hadn't even done that yet! I also posted some patches[3] to the list to fix a bug in my previous crosvm deadlock fix, and to improve some related documentation. As usual, these were kindly reviewed by Cole. Next, I turned my attention to other forms of hardware isolation. Wayland was a bit special, because despite crosvm including a virtual "Wayland device", it's not really hardware, and so it required an approach to isolation that will be quite different to other crosvm virtual devices. My hope is that other virtual devices should all be substantially similar to each other. The basic idea for actual hardware isolation is that rather than having drivers in the host kernel for USB, network devices, etc. those will be exposed to dedicated VMs as virtual PCI devices. This should substantially reduce host kernel attack surface. crosvm virtual devices will be run in these device VMs, and communicate over virtio with application VMs as normal. This will require implementing in crosvm a virtio proxy device, than allows for the crosvm running an application VM to forward virtio communication to the virtual device running in userspace in the driver VM. (The reason devices aren't attached to application VMs directly but run in seperate device VMs is that hardware is probably not going to be very happy if multiple kernels are trying to talk to it at the same time. Additionally, this indirection means that application VMs only have to use the one virtio driver for that device category, rather than any of the hundreds of drivers for different hardware in that category. If one of those drivers had a vulnerability, this should help to contain it to the device VM.) So I started writing this virtio proxy. The basic idea is to copy virtio buffers from application VM guest memory into memory that can be shared with the userspace virtual device in the device VM. I can't find any prior art on this (which is not unusual -- not many systems isolate drivers in this way), so this has required a lot of looking back at the virtio paper[4] and spec[5] to make sure I understand what to do here. As I write this, the next problem to solve is integrating some sort of memory allocator that can manage buffer allocations in the shared memory that the virtual device looks at. This is a new area for me that I'd appreciate advice on if anybody can give it -- think of it like, I have a memfd, mmaped into my process, and I would like to dynamically allocate and release memory buffers of dynamic sizes in that region. I'm sure there's a library I'll be able to plug in for this. [2]: https://spectrum-os.org/git/crosvm/?h=interguest [3]: https://spectrum-os.org/lists/archives/spectrum-devel/SJ0PR03MB55819DE7E13B… [4]: https://www.ozlabs.org/~rusty/virtio-spec/virtio-paper.pdf [5]: https://docs.oasis-open.org/virtio/virtio/v1.1/csprd01/virtio-v1.1-csprd01.… As usual, big thank you to Cole for reviewing patches, and for finding room for improvement even in languages/areas he isn't familiar with. It feels nice to have done some thinking about the project at a slightly higher level than I have been recently, and to know where I am on the way to the next milestone. Having taken a lot of time away from the milestone list this year to work on fundamentals, it's good to feel like I'm getting back on track.

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[PATCH crosvm 0/2] Fix deadlock on early VmRequest
by Alyssa Ross 09 Jul '20

09 Jul '20

This is the problem you might have seen me complaining about on IRC a couple of days ago. A detailed explanation of the issue and the fix can be found in the second patch message. The fix consists of two patches. The first just adds an API that's needed by the refactored, fixed code. The actual bug fix is in the second patch. Alyssa Ross (2): msg_socket: introduce UnixSeqpacketExt crosvm: fix deadlock on early VmRequest devices/src/virtio/block.rs | 5 + msg_socket/src/lib.rs | 52 ++++++---- src/linux.rs | 201 ++++++++++++++++++++++++++++++------ vm_control/src/lib.rs | 57 +++++++--- 4 files changed, 245 insertions(+), 70 deletions(-) -- 2.26.2

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[PATCH crosvm 1/2] sys_util: make UnixSeqpacket::recv use libc::recv
by Alyssa Ross 08 Jul '20

08 Jul '20

It's very surprising that a method called "recv" would end up calling read(). When UnixSeqpacket was introduced in 1d44223f9, the method was called "read", so this behaviour made more sense. It was renamed to "recv" in b7196e2a1, but the implementation was not changed to call libc::recv. In most cases, according to recv(2), the difference between read() and recv() doesn't matter: > The only difference between recv() and read(2) is the presence of > flags. With a zero flags argument, recv() is generally equivalent > to read(2) (but see NOTES). But the NOTES section explains that > If a zero-length datagram is pending, read(2) and recv() with a > flags argument of zero provide different behavior. In this > circumstance, read(2) has no effect (the datagram remains pending), > while recv() consumes the pending datagram. This means that, while we might expect UnixSeqpacket::recv(&mut []) to mirror the behaviour of recv() and discard a message despite the empty buffer, it would actually leave it there. This became relevant when I implemented the startup message queue in 5bd2e7f60, because I used an empty recv to drop the ready message from the socket, since it was only used for polling and I didn't care about the content. But, it turns out that my UnixSeqpacket::recv call did nothing, and left the message on the socket. This wasn't immediately noticeable, but it meant that when a message came through on the control socket later, it would actually get the ready message from UnixSeqpacket::recv, rather than the expected message on the control socket. For example, trying to use crosvm disk resize would print a message like the following: > [ERROR:vm_control/src/lib.rs:649] unexpected disk socket result: Ready > [ERROR:devices/src/virtio/block.rs:334] Attempted to resize read-only block device We can see that it does try to process the received message, but first it tries to do something with the Ready message, which should have been discarded by now. With this fix applied, we can see that it now receives and tries to process the correct message (but then fails because the VM I tested didn't support disk resizing!): > [ERROR:devices/src/virtio/block.rs:334] Attempted to resize read-only block device Fixes: b7196e2a1c1eb7123e7eace5418b7eb4a3e24dbe Fixes: 5bd2e7f606b726b598fdc26fe26a9b4029fab6d3 Cc: Cole Helbling <cole.e.helbling(a)outlook.com> --- This is the fix I described in This Week in Spectrum[1]. [1]: https://spectrum-os.org/lists/archives/spectrum-discuss/8736654ij2.fsf@alys… sys_util/src/net.rs | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/sys_util/src/net.rs b/sys_util/src/net.rs index 71ab3eeb5..82b4f5bb0 100644 --- a/sys_util/src/net.rs +++ b/sys_util/src/net.rs @@ -197,7 +197,7 @@ impl UnixSeqpacket { } } - /// Read data from the socket fd to a given buffer + /// Receive data from the socket fd to a given buffer. /// /// # Arguments /// * `buf` - A mut reference to the data buffer. @@ -206,11 +206,11 @@ impl UnixSeqpacket { /// * `usize` - The size of bytes read to the buffer. /// /// # Errors - /// Returns error when `libc::read` failed. + /// Returns error when `libc::recv` failed. pub fn recv(&self, buf: &mut [u8]) -> io::Result<usize> { // Safe since we make sure the input `count` == `buf.len()` and handle the returned error. unsafe { - let ret = libc::read(self.fd, buf.as_mut_ptr() as *mut _, buf.len()); + let ret = libc::recv(self.fd, buf.as_mut_ptr() as *mut _, buf.len(), 0); if ret < 0 { Err(io::Error::last_os_error()) } else { -- 2.26.2

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This Week in Spectrum, 2020-W27
by Alyssa Ross 06 Jul '20

06 Jul '20

I really didn't want this to be another week where I posted about how I was still trying to patch Wayland to do virtio_wl, and I am delighted to have just discovered it's not going to be! crosvm ------ I realised that emulating accept(2) for the Wayland compositor socket in the way I'd planned would require some crosvm rework. I want to have a host proxy program that accepts the connection, then connects the connection socket to crosvm. I had made it possible to dynamically add sockets to the crosvm Wl device through the control socket, but this turned out not be enough, because crosvm would store virtio_wl sockets in a BTreeMap<String, PathBuf>, and then use connect(2) to connect to the socket when asked to by the guest kernel. This works fine for e.g. connecting to a host Wayland compositor, which is what crosvm was designed for, but it wouldn't work for opening a connection socket from accept(2), because you can only connect to a listening socket. So instead, I modified the `crosvm wl add' command to take a file descriptor pointing to the connection socket. I made crosvm store sockets as an enum that looks like this: enum WaylandSocket { Listening(PathBuf), NonListening(UnixStream), } This way, when it gets asked by the VM to connect to a socket, it can either connect to a listening socket at its path using connect(2), or just use the existing file descriptor if it's a non-listening socket. A NonListening socket will be consumed by a connection, so when the VM close(2)s it, it'll go away, and on the host side the connection will finish as expected. Listening sockets can be connected to repeatedly, as before. I also added support to `crosvm add wl' for dynamic socket names. So it's possible to do `crosvm add wl wl-conn-%d', and connections will be added with names like `wl-conn-0', `wl-conn-1', etc. So it's easy to get unique names for connection sockets. The chosen name is printed by the command, so the caller knows what name to tell the VM to connect to. I also found and fixed a bug with the previous crosvm deadlock fix[1]. I had assumed that device_sock.recv(&mut []) would drop a message from the (SOCK_SEQPACKET) socket, without having to read any of it. But UnixSeqpacket::recv calls libc::read, and read(2) tells us that: > In the absence of any errors, or if read() does not check for errors, > a read() with a count of 0 returns zero and has no other effects. So this was in fact doing nothing at all. I don't know why crosvm's UnixSeqpacket::recv calls read() instead of recv(), but it's always been like that and I'm guessing this sort of thing (from recv(2)) might have something to do with it: > The only difference between recv() and read(2) is the presence of > flags. With a zero flags argument, recv() is generally equivalent to > read(2) (but see NOTES). So probably read() just looked like a nicer way to recv() when no flags were needed. But, unfortunately, zero-byte reads are when the aforementioned NOTES section becomes relevant: > If a zero-length datagram is pending, read(2) and recv() with a flags > argument of zero provide different behavior. In this circumstance, > read(2) has no effect (the datagram remains pending), while recv() > consumes the pending datagram. So, my assumption that UnixSeqpacket::recv(&mut []) would consume a message turned out to be quite reasonable -- the surprising thing was that a method called `recv' would call read() rather than recv(). I think the best fix here will be to just make it call recv() instead, rather than modifying my code to do UnixSeqpacket::recv(&mut [0]) or something, to prevent further nasty surprises with this in future. [1]: https://spectrum-os.org/lists/archives/spectrum-devel/20200614114344.22642-… Wayland ------- I created API-compatible implementations of the libc sendmsg(2) and recvmsg(2) functions for virtio_wl sockets. This was quite an achievement, because the API (which allows you to send and receive data and file descriptors, as well as other things I don't intend to support) is rather arcane (see the example in cmsg(3) if you're not familiar with them). I wrote unit tests for them, and it took a long time before they worked reliably. Once I had these, though, I could find the places where Wayland called sendmsg() and recvmsg() and fall back to the virtio_wl-based implementations if the standard functions failed with ENOTSOCK. I stubbed out some stuff that isn't going to work over virtio_wl, like looking up the pid of the Wayland client through getsockopt(2). I also had to resort to a few hacks, like faking support for MSG_DONTWAIT by using fcntl(2) to set O_NONBLOCK on the socket, recv()ing from it, and then removing O_NONBLOCK again, or faking mremap(2) by munmap()-ing and mmap()-ing. We will want to clean these up later by implementing the required missing functionality in the virtio_wl kernel module. In the first case, at least, this should be pretty straightforward, because it supports non-blocking operations if the socket is O_NONBLOCK -- it just needs to accept a MSG_DONTWAIT option as well. The VIRTWL_IOCTL_{SEND,RECV} syscalls don't currently have a flags argument, so that'll need to be added. I implemented this bit by bit, at every step trying to run Alacritty on my host system, connected to the virtio_wl Wayland server socket through the accept() proxy, and using strace and some printf()-debugging to see where the Wayland compositor in the VM would get stuck, and about an hour ago, it finally worked! For the first time, a Wayland compositor running in a VM can display an application running outside of it. (Obviously we'll want the application to be running in another VM rather than on the host, but that's similar enough that it probably works already -- I just haven't tested it yet.) This feels like a huge achievement. I've been working towards it for so long. Next week, I'll be cleaning up this code and posting patches for all of it. Then I'll probably move on to other sorts of device virtualization, like running a virtual network device in a VM. I'm feeling so much more positive about the direction of the project than I was before. It's been difficult to make myself keep going making little progress for the last couple of weeks, and it's great that I've managed to pick things up again so much. I hope that the level of detail in this email is enough to make up for the brevity of last week's! I'm sending late again, too, but only by a couple of minutes -- I didn't expect this email to take over an hour to write, but there we go. Thanks for reading! I hope you're looking forward to seeing where things go from here as much as I am.

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This (Last) Week in Spectrum, 2020-W26
by Alyssa Ross 29 Jun '20

29 Jun '20

This is going to be a very short one, and it's coming a day late, because I have been busy and didn't want to stop yesterday. 2020-W22's TWiS was sent a day early, so the delay is balanced out. :) Wayland ------- I'm finally making progress with the Wayland stuff I've been staring at for the past two weeks! Now that I'm unblocked, things feel like they're moving very quickly. I've modified a Wayland compositor and libwayland-server to use a virtio_wl socket. I've also implemented the compositor side of the accept(2) fallback. Just now, I finished writing a proxy program that implements the host side of that. Next up is testing it. After that, I think we might be there? But it's also possible I have my head so deep in it there's another bit that I've forgotten.

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This Week in Spectrum, 2020-W25
by Alyssa Ross 21 Jun '20

21 Jun '20

Another week that ended up being a detour from the Wayland work I wanted to do, unfortunately. I think this will be the end of it, though. crosvm ------ Fixed[1] an error in my crosvm deadlock fix[2] from last week. Due to an oversight (obvious as soon as I tried to test the affected devices, and from looking at the code in retrospect), this actually broke the devices that were *not* affected by the deadlock, which I had neglected to properly test. Fortunately, it was a very small and easy fix. I also had an interesting (and ongoing) conversation[3] with Cole about the deadlock fix in the mailing list thread. It's one of those situations where getting to talk about the code with another person and having to explain things is going to result in much better code. So we'll end up with a much tidier fix than what I came up with on my own. Thanks to Cole for his feedback and this opportunity. It's great to know that somebody else is passing an eye over my code. [1]: https://spectrum-os.org/git/crosvm/commit/?id=ca5bdd2ac3e473e9b082c44c2870f… [2]: https://spectrum-os.org/lists/archives/spectrum-devel/20200614114344.22642-… [3]: https://spectrum-os.org/lists/archives/spectrum-devel/CH2PR14MB357902F38908… Wayland ------- My current area of attention is modifying Wayland to use a virtio_wl socket as the display socket. Preparing to start implementing that this week, it occurred to me that working on it using my current setup was going to be extremely time consuming. Up until now, I've been doing Nix VM rebuilds when I want to test a change to, for example, wlroots. This means rebuilding, in that case, wlroots and all dependencies (i.e. Wayfire). In the case of wlroots, it's not so bad because rebuilding two packages doesn't take all that long, but it wasn't going to work for Wayland. So I decided that the best way forward would be to create a VM running a traditional Linux distribution, in which I could hack on Wayland without having to restart the VM or rebuild all of its dependents. To that end, I spent much of this week setting up an Alpine VM that can be run under both crosvm and QEMU. (Configuring networking with crosvm is hard for a one-off like this, but QEMU has a built-in userspace networking stack[4] that makes it easy, so when I want to, e.g. install a package, I can boot with QEMU to do that, and then go back to crosvm for testing virtio_wl things.) This resulted in a Nixpkgs pull request[5] to package Alpine's apk package manager, which was used in building the VM image. As of this afternoon, I have this VM all set up and ready to go. I have a script that runs it under crosvm with a virtio_wl socket available to try to connect Wayland to, and another virtio_wl socket connected to the host Wayland compositor for testing. It also sets up some limited networking that allows me to SSH into the VM, but does not allow the VM to access the internet. A separate script runs the VM under QEMU with full networking. The VM has Wayland, wlroots, and Sway (the choice of wlroots-based compositor is irrelevant to this work, and Sway is easier to build) installed from source, and because I can SSH to it I can edit files in the VM easily from my host Emacs using TRAMP[6]. All of this will allow me to iterate on the Wayland work without having to wait upwards of an hour to test each change. This was actually the first time I'd ever booted a VM image in crosvm that I hadn't generated specifically for that purpose myself with Nix. I improved my understanding of crosvm in a few ways in the process (although not anything concrete enough I can think of to write down here). [4]: https://wiki.qemu.org/Documentation/Networking#User_Networking_.28SLIRP.29 [5]: https://github.com/NixOS/nixpkgs/pull/90676 [6]: https://www.gnu.org/software/tramp/ Next week, I'll continue with the Wayland work. It shouldn't be all that much work in the end, but getting set up to actually be able to do it has been annoyingly complicated.

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