[PATCH v3 1/3] tools/mount-flatpak: init
I tried to build this with Meson, but pathrs depends on thiserror, which tries to read OUT_DIR, and support for setting that isn't currently in a Meson release, and requires nightly Rust, so build with Cargo for now and we can revisit that later. Link: https://github.com/mesonbuild/meson/pull/15148 Link: https://github.com/rust-lang/rust/issues/118372 Signed-off-by: Alyssa Ross <hi@alyssa.is> --- v3: Take the user data partition root and path to the Flatpak repository within it as separate parameters, to avoid calling Root::open() on an untrusted path. Suggested by Demi out of band. v2: https://spectrum-os.org/lists/archives/spectrum-devel/20251124194846.16338-1... LICENSES/MPL-2.0.txt | 373 +++++++++++++++++++++++++ pkgs/default.nix | 1 + tools/mount-flatpak/Cargo.lock | 238 ++++++++++++++++ tools/mount-flatpak/Cargo.lock.license | 2 + tools/mount-flatpak/Cargo.toml | 11 + tools/mount-flatpak/config | 7 + tools/mount-flatpak/default.nix | 25 ++ tools/mount-flatpak/src/keyfile.rs | 189 +++++++++++++ tools/mount-flatpak/src/main.rs | 252 +++++++++++++++++ tools/mount-flatpak/src/metadata.rs | 19 ++ 10 files changed, 1117 insertions(+) create mode 100644 LICENSES/MPL-2.0.txt create mode 100644 tools/mount-flatpak/Cargo.lock create mode 100644 tools/mount-flatpak/Cargo.lock.license create mode 100644 tools/mount-flatpak/Cargo.toml create mode 100644 tools/mount-flatpak/config create mode 100644 tools/mount-flatpak/default.nix create mode 100644 tools/mount-flatpak/src/keyfile.rs create mode 100644 tools/mount-flatpak/src/main.rs create mode 100644 tools/mount-flatpak/src/metadata.rs diff --git a/LICENSES/MPL-2.0.txt b/LICENSES/MPL-2.0.txt new file mode 100644 index 0000000..d0a1fa1 --- /dev/null +++ b/LICENSES/MPL-2.0.txt @@ -0,0 +1,373 @@ +Mozilla Public License Version 2.0 +================================== + +1. Definitions +-------------- + +1.1. "Contributor" + means each individual or legal entity that creates, contributes to + the creation of, or owns Covered Software. + +1.2. "Contributor Version" + means the combination of the Contributions of others (if any) used + by a Contributor and that particular Contributor's Contribution. + +1.3. "Contribution" + means Covered Software of a particular Contributor. + +1.4. "Covered Software" + means Source Code Form to which the initial Contributor has attached + the notice in Exhibit A, the Executable Form of such Source Code + Form, and Modifications of such Source Code Form, in each case + including portions thereof. + +1.5. "Incompatible With Secondary Licenses" + means + + (a) that the initial Contributor has attached the notice described + in Exhibit B to the Covered Software; or + + (b) that the Covered Software was made available under the terms of + version 1.1 or earlier of the License, but not also under the + terms of a Secondary License. + +1.6. "Executable Form" + means any form of the work other than Source Code Form. + +1.7. "Larger Work" + means a work that combines Covered Software with other material, in + a separate file or files, that is not Covered Software. + +1.8. "License" + means this document. + +1.9. "Licensable" + means having the right to grant, to the maximum extent possible, + whether at the time of the initial grant or subsequently, any and + all of the rights conveyed by this License. + +1.10. "Modifications" + means any of the following: + + (a) any file in Source Code Form that results from an addition to, + deletion from, or modification of the contents of Covered + Software; or + + (b) any new file in Source Code Form that contains any Covered + Software. + +1.11. "Patent Claims" of a Contributor + means any patent claim(s), including without limitation, method, + process, and apparatus claims, in any patent Licensable by such + Contributor that would be infringed, but for the grant of the + License, by the making, using, selling, offering for sale, having + made, import, or transfer of either its Contributions or its + Contributor Version. + +1.12. "Secondary License" + means either the GNU General Public License, Version 2.0, the GNU + Lesser General Public License, Version 2.1, the GNU Affero General + Public License, Version 3.0, or any later versions of those + licenses. + +1.13. "Source Code Form" + means the form of the work preferred for making modifications. + +1.14. "You" (or "Your") + means an individual or a legal entity exercising rights under this + License. For legal entities, "You" includes any entity that + controls, is controlled by, or is under common control with You. For + purposes of this definition, "control" means (a) the power, direct + or indirect, to cause the direction or management of such entity, + whether by contract or otherwise, or (b) ownership of more than + fifty percent (50%) of the outstanding shares or beneficial + ownership of such entity. + +2. License Grants and Conditions +-------------------------------- + +2.1. Grants + +Each Contributor hereby grants You a world-wide, royalty-free, +non-exclusive license: + +(a) under intellectual property rights (other than patent or trademark) + Licensable by such Contributor to use, reproduce, make available, + modify, display, perform, distribute, and otherwise exploit its + Contributions, either on an unmodified basis, with Modifications, or + as part of a Larger Work; and + +(b) under Patent Claims of such Contributor to make, use, sell, offer + for sale, have made, import, and otherwise transfer either its + Contributions or its Contributor Version. + +2.2. Effective Date + +The licenses granted in Section 2.1 with respect to any Contribution +become effective for each Contribution on the date the Contributor first +distributes such Contribution. + +2.3. Limitations on Grant Scope + +The licenses granted in this Section 2 are the only rights granted under +this License. No additional rights or licenses will be implied from the +distribution or licensing of Covered Software under this License. +Notwithstanding Section 2.1(b) above, no patent license is granted by a +Contributor: + +(a) for any code that a Contributor has removed from Covered Software; + or + +(b) for infringements caused by: (i) Your and any other third party's + modifications of Covered Software, or (ii) the combination of its + Contributions with other software (except as part of its Contributor + Version); or + +(c) under Patent Claims infringed by Covered Software in the absence of + its Contributions. + +This License does not grant any rights in the trademarks, service marks, +or logos of any Contributor (except as may be necessary to comply with +the notice requirements in Section 3.4). + +2.4. Subsequent Licenses + +No Contributor makes additional grants as a result of Your choice to +distribute the Covered Software under a subsequent version of this +License (see Section 10.2) or under the terms of a Secondary License (if +permitted under the terms of Section 3.3). + +2.5. Representation + +Each Contributor represents that the Contributor believes its +Contributions are its original creation(s) or it has sufficient rights +to grant the rights to its Contributions conveyed by this License. + +2.6. Fair Use + +This License is not intended to limit any rights You have under +applicable copyright doctrines of fair use, fair dealing, or other +equivalents. + +2.7. Conditions + +Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted +in Section 2.1. + +3. Responsibilities +------------------- + +3.1. Distribution of Source Form + +All distribution of Covered Software in Source Code Form, including any +Modifications that You create or to which You contribute, must be under +the terms of this License. You must inform recipients that the Source +Code Form of the Covered Software is governed by the terms of this +License, and how they can obtain a copy of this License. You may not +attempt to alter or restrict the recipients' rights in the Source Code +Form. + +3.2. Distribution of Executable Form + +If You distribute Covered Software in Executable Form then: + +(a) such Covered Software must also be made available in Source Code + Form, as described in Section 3.1, and You must inform recipients of + the Executable Form how they can obtain a copy of such Source Code + Form by reasonable means in a timely manner, at a charge no more + than the cost of distribution to the recipient; and + +(b) You may distribute such Executable Form under the terms of this + License, or sublicense it under different terms, provided that the + license for the Executable Form does not attempt to limit or alter + the recipients' rights in the Source Code Form under this License. + +3.3. Distribution of a Larger Work + +You may create and distribute a Larger Work under terms of Your choice, +provided that You also comply with the requirements of this License for +the Covered Software. If the Larger Work is a combination of Covered +Software with a work governed by one or more Secondary Licenses, and the +Covered Software is not Incompatible With Secondary Licenses, this +License permits You to additionally distribute such Covered Software +under the terms of such Secondary License(s), so that the recipient of +the Larger Work may, at their option, further distribute the Covered +Software under the terms of either this License or such Secondary +License(s). + +3.4. Notices + +You may not remove or alter the substance of any license notices +(including copyright notices, patent notices, disclaimers of warranty, +or limitations of liability) contained within the Source Code Form of +the Covered Software, except that You may alter any license notices to +the extent required to remedy known factual inaccuracies. + +3.5. Application of Additional Terms + +You may choose to offer, and to charge a fee for, warranty, support, +indemnity or liability obligations to one or more recipients of Covered +Software. However, You may do so only on Your own behalf, and not on +behalf of any Contributor. You must make it absolutely clear that any +such warranty, support, indemnity, or liability obligation is offered by +You alone, and You hereby agree to indemnify every Contributor for any +liability incurred by such Contributor as a result of warranty, support, +indemnity or liability terms You offer. You may include additional +disclaimers of warranty and limitations of liability specific to any +jurisdiction. + +4. Inability to Comply Due to Statute or Regulation +--------------------------------------------------- + +If it is impossible for You to comply with any of the terms of this +License with respect to some or all of the Covered Software due to +statute, judicial order, or regulation then You must: (a) comply with +the terms of this License to the maximum extent possible; and (b) +describe the limitations and the code they affect. Such description must +be placed in a text file included with all distributions of the Covered +Software under this License. Except to the extent prohibited by statute +or regulation, such description must be sufficiently detailed for a +recipient of ordinary skill to be able to understand it. + +5. Termination +-------------- + +5.1. The rights granted under this License will terminate automatically +if You fail to comply with any of its terms. However, if You become +compliant, then the rights granted under this License from a particular +Contributor are reinstated (a) provisionally, unless and until such +Contributor explicitly and finally terminates Your grants, and (b) on an +ongoing basis, if such Contributor fails to notify You of the +non-compliance by some reasonable means prior to 60 days after You have +come back into compliance. Moreover, Your grants from a particular +Contributor are reinstated on an ongoing basis if such Contributor +notifies You of the non-compliance by some reasonable means, this is the +first time You have received notice of non-compliance with this License +from such Contributor, and You become compliant prior to 30 days after +Your receipt of the notice. + +5.2. If You initiate litigation against any entity by asserting a patent +infringement claim (excluding declaratory judgment actions, +counter-claims, and cross-claims) alleging that a Contributor Version +directly or indirectly infringes any patent, then the rights granted to +You by any and all Contributors for the Covered Software under Section +2.1 of this License shall terminate. + +5.3. In the event of termination under Sections 5.1 or 5.2 above, all +end user license agreements (excluding distributors and resellers) which +have been validly granted by You or Your distributors under this License +prior to termination shall survive termination. + +************************************************************************ +* * +* 6. Disclaimer of Warranty * +* ------------------------- * +* * +* Covered Software is provided under this License on an "as is" * +* basis, without warranty of any kind, either expressed, implied, or * +* statutory, including, without limitation, warranties that the * +* Covered Software is free of defects, merchantable, fit for a * +* particular purpose or non-infringing. The entire risk as to the * +* quality and performance of the Covered Software is with You. * +* Should any Covered Software prove defective in any respect, You * +* (not any Contributor) assume the cost of any necessary servicing, * +* repair, or correction. This disclaimer of warranty constitutes an * +* essential part of this License. No use of any Covered Software is * +* authorized under this License except under this disclaimer. * +* * +************************************************************************ + +************************************************************************ +* * +* 7. Limitation of Liability * +* -------------------------- * +* * +* Under no circumstances and under no legal theory, whether tort * +* (including negligence), contract, or otherwise, shall any * +* Contributor, or anyone who distributes Covered Software as * +* permitted above, be liable to You for any direct, indirect, * +* special, incidental, or consequential damages of any character * +* including, without limitation, damages for lost profits, loss of * +* goodwill, work stoppage, computer failure or malfunction, or any * +* and all other commercial damages or losses, even if such party * +* shall have been informed of the possibility of such damages. This * +* limitation of liability shall not apply to liability for death or * +* personal injury resulting from such party's negligence to the * +* extent applicable law prohibits such limitation. Some * +* jurisdictions do not allow the exclusion or limitation of * +* incidental or consequential damages, so this exclusion and * +* limitation may not apply to You. * +* * +************************************************************************ + +8. Litigation +------------- + +Any litigation relating to this License may be brought only in the +courts of a jurisdiction where the defendant maintains its principal +place of business and such litigation shall be governed by laws of that +jurisdiction, without reference to its conflict-of-law provisions. +Nothing in this Section shall prevent a party's ability to bring +cross-claims or counter-claims. + +9. Miscellaneous +---------------- + +This License represents the complete agreement concerning the subject +matter hereof. If any provision of this License is held to be +unenforceable, such provision shall be reformed only to the extent +necessary to make it enforceable. Any law or regulation which provides +that the language of a contract shall be construed against the drafter +shall not be used to construe this License against a Contributor. + +10. Versions of the License +--------------------------- + +10.1. New Versions + +Mozilla Foundation is the license steward. Except as provided in Section +10.3, no one other than the license steward has the right to modify or +publish new versions of this License. Each version will be given a +distinguishing version number. + +10.2. Effect of New Versions + +You may distribute the Covered Software under the terms of the version +of the License under which You originally received the Covered Software, +or under the terms of any subsequent version published by the license +steward. + +10.3. Modified Versions + +If you create software not governed by this License, and you want to +create a new license for such software, you may create and use a +modified version of this License if you rename the license and remove +any references to the name of the license steward (except to note that +such modified license differs from this License). + +10.4. Distributing Source Code Form that is Incompatible With Secondary +Licenses + +If You choose to distribute Source Code Form that is Incompatible With +Secondary Licenses under the terms of this version of the License, the +notice described in Exhibit B of this License must be attached. + +Exhibit A - Source Code Form License Notice +------------------------------------------- + + 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/. + +If it is not possible or desirable to put the notice in a particular +file, then You may include the notice in a location (such as a LICENSE +file in a relevant directory) where a recipient would be likely to look +for such a notice. + +You may add additional accurate notices of copyright ownership. + +Exhibit B - "Incompatible With Secondary Licenses" Notice +--------------------------------------------------------- + + This Source Code Form is "Incompatible With Secondary Licenses", as + defined by the Mozilla Public License, v. 2.0. diff --git a/pkgs/default.nix b/pkgs/default.nix index cc60228..6829185 100644 --- a/pkgs/default.nix +++ b/pkgs/default.nix @@ -36,6 +36,7 @@ let path: (import path { inherit (self) callPackage; }).override; rootfs = self.callSpectrumPackage ../host/rootfs {}; + mount-flatpak = self.callSpectrumPackage ../tools/mount-flatpak {}; spectrum-build-tools = self.callSpectrumPackage ../tools { appSupport = false; buildSupport = true; diff --git a/tools/mount-flatpak/Cargo.lock b/tools/mount-flatpak/Cargo.lock new file mode 100644 index 0000000..8cb5663 --- /dev/null +++ b/tools/mount-flatpak/Cargo.lock @@ -0,0 +1,238 @@ +# This file is automatically @generated by Cargo. +# It is not intended for manual editing. +version = 4 + +[[package]] +name = "bitflags" +version = "2.10.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "812e12b5285cc515a9c72a5c1d3b6d46a19dac5acfef5265968c166106e31dd3" + +[[package]] +name = "cfg-if" +version = "1.0.4" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801" + +[[package]] +name = "either" +version = "1.15.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "48c757948c5ede0e46177b7add2e67155f70e33c07fea8284df6576da70b3719" + 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+source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "0562428422c63773dad2c345a1882263bbf4d65cf3f42e90921f787ef5ad58e7" +dependencies = [ + "wit-bindgen", +] + +[[package]] +name = "windows-link" +version = "0.2.1" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5" + +[[package]] +name = "windows-sys" +version = "0.61.2" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "ae137229bcbd6cdf0f7b80a31df61766145077ddf49416a728b02cb3921ff3fc" +dependencies = [ + "windows-link", +] + +[[package]] +name = "wit-bindgen" +version = "0.46.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "f17a85883d4e6d00e8a97c586de764dabcc06133f7f1d55dce5cdc070ad7fe59" diff --git a/tools/mount-flatpak/Cargo.lock.license b/tools/mount-flatpak/Cargo.lock.license new file mode 100644 index 0000000..d705e97 --- /dev/null +++ b/tools/mount-flatpak/Cargo.lock.license @@ -0,0 +1,2 @@ +SPDX-License-Identifier: CC0-1.0 +SPDX-FileCopyrightText: 2024 Alyssa Ross <hi@alyssa.is> diff --git a/tools/mount-flatpak/Cargo.toml b/tools/mount-flatpak/Cargo.toml new file mode 100644 index 0000000..670be2f --- /dev/null +++ b/tools/mount-flatpak/Cargo.toml @@ -0,0 +1,11 @@ +# SPDX-License-Identifier: CC0-1.0 +# SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +[package] +name = "mount-flatpak" +edition = "2024" + +[dependencies] +libc = "0.2.177" +pathrs = "0.2.1" +rustix = "1.1.2" diff --git a/tools/mount-flatpak/config b/tools/mount-flatpak/config new file mode 100644 index 0000000..b3c2bee --- /dev/null +++ b/tools/mount-flatpak/config @@ -0,0 +1,7 @@ +# SPDX-License-Identifier: CC0-1.0 +# SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +[core] +repo_version=1 +mode=bare-user-only +min-free-space-size=500MB diff --git a/tools/mount-flatpak/default.nix b/tools/mount-flatpak/default.nix new file mode 100644 index 0000000..f364fd7 --- /dev/null +++ b/tools/mount-flatpak/default.nix @@ -0,0 +1,25 @@ +# SPDX-FileCopyrightText: 2024-2025 Alyssa Ross <hi@alyssa.is> +# SPDX-License-Identifier: MIT + +import ../../lib/call-package.nix ( +{ src, lib, rustPlatform }: + +rustPlatform.buildRustPackage { + name = "mount-flatpak"; + + src = lib.fileset.toSource { + root = ../..; + fileset = lib.fileset.intersection src ./.; + }; + sourceRoot = "source/tools/mount-flatpak"; + + cargoLock.lockFile = ./Cargo.lock; + + env = { + MOUNT_FLATPAK_CONFIG_PATH = "${placeholder "out"}/share/spectrum/flatpak-config"; + }; + + postInstall = '' + install -Dm 0755 config $MOUNT_FLATPAK_CONFIG_PATH + ''; +}) (_: {}) diff --git a/tools/mount-flatpak/src/keyfile.rs b/tools/mount-flatpak/src/keyfile.rs new file mode 100644 index 0000000..fa746b3 --- /dev/null +++ b/tools/mount-flatpak/src/keyfile.rs @@ -0,0 +1,189 @@ +// Copyright 2021 System76 <info@system76.com> +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> +// SPDX-License-Identifier: MPL-2.0 + +// Adapted from freedesktop-desktop-entry 0.7.19. + +use std::collections::BTreeMap; +use std::fmt::{self, Display, Formatter}; + +type Group = BTreeMap<String, String>; + +#[derive(Debug)] +pub enum DecodeError { + KeyValueWithoutAGroup, + InvalidKey, + InvalidValue, +} + +impl Display for DecodeError { + fn fmt(&self, f: &mut Formatter) -> fmt::Result { + match self { + Self::KeyValueWithoutAGroup => write!(f, "key/value without a group"), + Self::InvalidKey => write!(f, "invalid key"), + Self::InvalidValue => write!(f, "invalid value"), + } + } +} + +pub fn parse(input: &str) -> Result<BTreeMap<String, Group>, DecodeError> { + let mut groups = BTreeMap::default(); + let mut active_group: Option<ActiveGroup> = None; + let mut active_keys: Option<ActiveKeys> = None; + + for line in input.lines() { + process_line(line, &mut groups, &mut active_group, &mut active_keys)?; + } + + if let Some(active_keys) = active_keys.take() { + match &mut active_group { + Some(active_group) => { + active_group + .group + .insert(active_keys.key_name, active_keys.value); + } + None => return Err(DecodeError::KeyValueWithoutAGroup), + } + } + + if let Some(mut group) = active_group.take() { + groups + .entry(group.group_name) + .or_default() + .append(&mut group.group); + } + + Ok(groups) +} + +struct ActiveGroup { + group_name: String, + group: Group, +} + +struct ActiveKeys { + key_name: String, + value: String, +} + +#[inline(never)] +fn process_line( + line: &str, + groups: &mut BTreeMap<String, Group>, + active_group: &mut Option<ActiveGroup>, + active_keys: &mut Option<ActiveKeys>, +) -> Result<(), DecodeError> { + if line.trim().is_empty() || line.starts_with('#') { + return Ok(()); + } + + let line_bytes = line.as_bytes(); + + // if group + if line_bytes[0] == b'[' { + if let Some(end) = line_bytes[1..].iter().rposition(|&b| b == b']') { + let group_name = &line[1..end + 1]; + + if let Some(active_keys) = active_keys.take() { + match active_group { + Some(active_group) => { + active_group + .group + .insert(active_keys.key_name, active_keys.value); + } + None => return Err(DecodeError::KeyValueWithoutAGroup), + } + } + + if let Some(mut group) = active_group.take() { + groups + .entry(group.group_name) + .or_default() + .append(&mut group.group); + } + + active_group.replace(ActiveGroup { + group_name: group_name.to_string(), + group: Group::default(), + }); + } + } + // else, if value + else if let Some(delimiter) = line_bytes.iter().position(|&b| b == b'=') { + let key = &line[..delimiter]; + let value = format_value(&line[delimiter + 1..])?; + + if key.is_empty() { + return Err(DecodeError::InvalidKey); + } + + if let Some(active_keys) = active_keys.take() { + match active_group { + Some(active_group) => { + active_group + .group + .insert(active_keys.key_name, active_keys.value); + } + None => return Err(DecodeError::KeyValueWithoutAGroup), + } + } + active_keys.replace(ActiveKeys { + key_name: key.trim().to_string(), + value, + }); + } + Ok(()) +} + +// https://specifications.freedesktop.org/desktop-entry-spec/latest/value-types... +#[inline] +fn format_value(input: &str) -> Result<String, DecodeError> { + let input = if let Some(input) = input.strip_prefix(" ") { + input + } else { + input + }; + + let mut res = String::with_capacity(input.len()); + + let mut last: usize = 0; + + for (i, v) in input.as_bytes().iter().enumerate() { + if *v != b'\\' { + continue; + } + + // edge case for // + if last > i { + continue; + } + + // when there is an \ at the end + if input.len() <= i + 1 { + return Err(DecodeError::InvalidValue); + } + + if last < i { + res.push_str(&input[last..i]); + } + + last = i + 2; + + match input.as_bytes()[i + 1] { + b's' => res.push(' '), + b'n' => res.push('\n'), + b't' => res.push('\t'), + b'r' => res.push('\r'), + b'\\' => res.push('\\'), + _ => { + return Err(DecodeError::InvalidValue); + } + } + } + + if last < input.len() { + res.push_str(&input[last..input.len()]); + } + + Ok(res) +} diff --git a/tools/mount-flatpak/src/main.rs b/tools/mount-flatpak/src/main.rs new file mode 100644 index 0000000..fd2f74f --- /dev/null +++ b/tools/mount-flatpak/src/main.rs @@ -0,0 +1,252 @@ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> +// SPDX-License-Identifier: EUPL-1.2+ + +mod keyfile; +mod metadata; + +use std::borrow::Cow; +use std::env::{ArgsOs, args_os}; +use std::ffi::OsStr; +use std::io; +use std::os::unix::prelude::*; +use std::path::{Path, PathBuf}; +use std::process::exit; + +use pathrs::Root; +use pathrs::flags::{OpenFlags, ResolverFlags}; +use rustix::fs::{CWD, FileType, fstat}; +use rustix::mount::{MoveMountFlags, OpenTreeFlags, move_mount, open_tree}; + +use metadata::extract_runtime; + +fn ex_usage() -> ! { + eprintln!("Usage: mount-flatpak installation app"); + exit(1); +} + +fn run(mut args: ArgsOs) -> Result<(), String> { + let Some(user_data_path) = args.next().map(PathBuf::from) else { + ex_usage(); + }; + let Some(installation_path) = args.next().map(PathBuf::from) else { + ex_usage(); + }; + let Some(app) = args.next() else { + ex_usage(); + }; + if args.next().is_some() { + ex_usage(); + } + + let mut source_installation_dir = Root::open(&user_data_path) + .map_err(|e| format!("opening source flatpak installation: {e}"))?; + source_installation_dir.set_resolver_flags(ResolverFlags::NO_SYMLINKS); + + std::fs::create_dir("flatpak") + .map_err(|e| format!("creating target flatpak installation: {e}"))?; + + let target_installation_dir = open_tree( + CWD, + "flatpak", + OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE, + ) + .map_err(|e| format!("opening target flatpak installation: {e}"))?; + let mut target_installation_dir = Root::from_fd(target_installation_dir); + target_installation_dir.set_resolver_flags(ResolverFlags::NO_SYMLINKS); + + let mut full_app_path = installation_path.join("app"); + full_app_path.push(&app); + full_app_path.push("current"); + let arch_and_branch = source_installation_dir + .readlink(&full_app_path) + .map_err(|e| format!("reading current app arch and branch: {e}"))?; + let mut components = arch_and_branch.components(); + let arch = components.next().unwrap().as_os_str(); + let branch = components.as_path().as_os_str(); + if branch.is_empty() { + return Err("can't infer branch from \"current\" link".to_string()); + } + + full_app_path.pop(); + full_app_path.push(&arch_and_branch); + full_app_path.push("active"); + let commit = source_installation_dir + .readlink(&full_app_path) + .map_err(|e| format!("reading active app commit: {e}"))? + .into_os_string(); + + full_app_path.pop(); + full_app_path.push(&commit); + let source_app_dir = source_installation_dir + .resolve(&full_app_path) + .map_err(|e| format!("opening source app directory: {e}"))?; + + let metadata = source_installation_dir + .resolve(full_app_path.join("metadata")) + .map_err(|e| format!("resolving app metadata: {e}"))?; + + let metadata_stat = + fstat(&metadata).map_err(|e| format!("checking app metadata is a regular file: {e}"))?; + let metadata_type = FileType::from_raw_mode(metadata_stat.st_mode); + if !metadata_type.is_file() { + let e = format!("type of app metadata is {metadata_type:?}, not RegularFile"); + return Err(e); + } + let metadata = metadata + .reopen(OpenFlags::O_RDONLY) + .map_err(|e| format!("opening app metadata: {e}"))?; + + let runtime = + extract_runtime(metadata).map_err(|e| format!("reading runtime from metadata: {e}"))?; + + let mut full_runtime_path = installation_path.join("runtime"); + full_runtime_path.push(runtime); + full_runtime_path.push("active"); + let runtime_commit = source_installation_dir + .readlink(&full_runtime_path) + .map_err(|e| format!("reading active runtime commit: {e}"))? + .into_os_string(); + + full_runtime_path.pop(); + full_runtime_path.push(&runtime_commit); + let source_runtime_dir = source_installation_dir + .resolve(&full_runtime_path) + .map_err(|e| format!("opening source runtime directory: {e}"))?; + + let target_app_dir = target_installation_dir + .mkdir_all(&full_app_path, &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating target app directory: {e}"))?; + let target_runtime_dir = target_installation_dir + .mkdir_all(&full_runtime_path, &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating target runtime directory: {e}"))?; + + let source_app_tree = open_tree( + &source_app_dir, + "", + OpenTreeFlags::AT_EMPTY_PATH + | OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE, + ) + .map_err(|e| format!("cloning source app tree: {e}"))?; + let source_runtime_tree = open_tree( + &source_runtime_dir, + "", + OpenTreeFlags::AT_EMPTY_PATH + | OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE, + ) + .map_err(|e| format!("cloning source runtime tree: {e}"))?; + + move_mount( + source_app_tree, + "", + target_app_dir, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting app directory: {e}"))?; + move_mount( + source_runtime_tree, + "", + target_runtime_dir, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting runtime directory: {e}"))?; + + target_installation_dir + .mkdir_all("repo/objects", &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating repo/objects: {e}"))?; + target_installation_dir + .mkdir_all("repo/tmp/cache", &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating repo/tmp/cache: {e}"))?; + let config_target = target_installation_dir + .create_file( + "repo/config", + OpenFlags::O_WRONLY | OpenFlags::O_CLOEXEC, + &PermissionsExt::from_mode(0o700), + ) + .map_err(|e| format!("creating repo/config: {e}"))?; + let config_source_path = env!("MOUNT_FLATPAK_CONFIG_PATH"); + let config_source = open_tree( + CWD, + config_source_path, + OpenTreeFlags::OPEN_TREE_CLONE | OpenTreeFlags::OPEN_TREE_CLOEXEC, + ) + .map_err(|e| format!("opening {config_source_path}: {e}"))?; + move_mount( + config_source, + "", + config_target, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting config: {e}"))?; + + let mut attr = libc::mount_attr { + attr_clr: libc::MOUNT_ATTR_NOSYMFOLLOW, + attr_set: libc::MOUNT_ATTR_RDONLY | libc::MOUNT_ATTR_NODEV, + propagation: 0, + userns_fd: 0, + }; + let empty = b"\0"; + // SAFETY: we pass a valid FD, and a valid mutable pointer with the correct size. + unsafe { + let r = libc::syscall( + libc::SYS_mount_setattr, + target_installation_dir.as_fd(), + empty.as_ptr() as *const libc::c_char, + (libc::AT_EMPTY_PATH | libc::AT_RECURSIVE) as libc::c_uint, + &mut attr as *mut libc::mount_attr, + size_of::<libc::mount_attr>() as libc::size_t, + ); + if r == -1 { + return Err(format!( + "setting target mount attributes: {}", + io::Error::last_os_error() + )); + } + } + move_mount( + target_installation_dir, + "", + CWD, + "flatpak", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH, + ) + .map_err(|e| format!("mounting target installation dir: {e}"))?; + + std::fs::create_dir("params").map_err(|e| format!("creating params directory: {e}"))?; + std::fs::write("params/id", app.as_bytes()).map_err(|e| format!("writing params/id: {e}"))?; + std::fs::write("params/commit", commit.as_bytes()) + .map_err(|e| format!("writing params/commit: {e}"))?; + std::fs::write("params/arch", arch.as_bytes()) + .map_err(|e| format!("writing params/arch: {e}"))?; + std::fs::write("params/branch", branch.as_bytes()) + .map_err(|e| format!("writing params/branch: {e}"))?; + std::fs::write("params/runtime-commit", runtime_commit.as_bytes()) + .map_err(|e| format!("writing params/runtime-commit: {e}"))?; + + Ok(()) +} + +fn main() { + let mut args = args_os(); + + let prog_name = args + .next() + .as_ref() + .map(Path::new) + .and_then(Path::file_name) + .map_or(Cow::Borrowed("mount-flatpak"), OsStr::to_string_lossy) + .into_owned(); + + if let Err(e) = run(args) { + eprintln!("{prog_name}: {e}"); + exit(1); + } +} diff --git a/tools/mount-flatpak/src/metadata.rs b/tools/mount-flatpak/src/metadata.rs new file mode 100644 index 0000000..dfc05b1 --- /dev/null +++ b/tools/mount-flatpak/src/metadata.rs @@ -0,0 +1,19 @@ +// SPDX-License-Identifier: EUPL-1.2+ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +use std::fs::File; +use std::io::read_to_string; + +use crate::keyfile::parse; + +pub fn extract_runtime(mut metadata: File) -> Result<String, String> { + let metadata = read_to_string(&mut metadata).map_err(|e| e.to_string())?; + let group = parse(&metadata).map_err(|e| e.to_string())?; + let application = group + .get("Application") + .ok_or_else(|| "Application group missing".to_string())?; + Ok(application + .get("runtime") + .ok_or_else(|| "runtime property missing".to_string())? + .clone()) +} base-commit: 4200cea7eb31f5b8d35bf4c00b879aa25cf1fb90 -- 2.51.0
Signed-off-by: Alyssa Ross <hi@alyssa.is> --- v3: no changes v2: https://spectrum-os.org/lists/archives/spectrum-devel/20251124194846.16338-3... img/app/default.nix | 1 + img/app/file-list.mk | 1 + .../image/etc/flatpak/installations.d/extra.conf | 5 +++++ img/app/image/etc/s6-rc/app/run | 14 +++++++++++++- 4 files changed, 20 insertions(+), 1 deletion(-) create mode 100644 img/app/image/etc/flatpak/installations.d/extra.conf diff --git a/img/app/default.nix b/img/app/default.nix index 6490ac2..c1a1706 100644 --- a/img/app/default.nix +++ b/img/app/default.nix @@ -49,6 +49,7 @@ let name = "vm-fhs-env"; targetPkgs = pkgs: appimageTools.defaultFhsEnvArgs.targetPkgs pkgs ++ [ pkgs.fuse + pkgs.flatpak (pkgs.busybox.override { enableMinimal = true; diff --git a/img/app/file-list.mk b/img/app/file-list.mk index 6934975..4fbdec2 100644 --- a/img/app/file-list.mk +++ b/img/app/file-list.mk @@ -3,6 +3,7 @@ FILES = \ image/etc/dbus-1/session.conf \ + image/etc/flatpak/installations.d/extra.conf \ image/etc/fstab \ image/etc/mdev.conf \ image/etc/mdev/iface \ diff --git a/img/app/image/etc/flatpak/installations.d/extra.conf b/img/app/image/etc/flatpak/installations.d/extra.conf new file mode 100644 index 0000000..448902b --- /dev/null +++ b/img/app/image/etc/flatpak/installations.d/extra.conf @@ -0,0 +1,5 @@ +# SPDX-License-Identifier: CC0-1.0 +# SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +[Installation "virtiofs"] +Path=/run/virtiofs/virtiofs0/config/flatpak diff --git a/img/app/image/etc/s6-rc/app/run b/img/app/image/etc/s6-rc/app/run index 601926b..4b3b8d6 100755 --- a/img/app/image/etc/s6-rc/app/run +++ b/img/app/image/etc/s6-rc/app/run @@ -1,6 +1,6 @@ #!/bin/execlineb -P # SPDX-License-Identifier: EUPL-1.2+ -# SPDX-FileCopyrightText: 2021, 2024 Alyssa Ross <hi@alyssa.is> +# SPDX-FileCopyrightText: 2021, 2024-2025 Alyssa Ross <hi@alyssa.is> export TMPDIR /run @@ -25,6 +25,18 @@ foreground { export LD_LIBRARY_PATH /lib64 /run/virtiofs/virtiofs0/config/run } + flatpak { + s6-envdir -fnL /run/virtiofs/virtiofs0/config/params + multisubstitute { + importas -iu id id + importas -iu arch arch + importas -iu branch branch + importas -iu commit commit + importas -iu runtime_commit runtime-commit + } + flatpak run --installation=virtiofs --arch=${arch} --branch=${branch} + --commit=${commit} --runtime-commit=${runtime_commit} $id + } nix { if { mount -t overlay -- 2.51.0
This is the entrypoint for running Flatpak applications. It would be good to only add mounts for the VM in virtiofsd's mount namespace, so we don't need to do lots of manual unmounts, but that's a wider change affecting more than just Flatpak. I've tested this by copying my host's Flatpak repository into a disk image, and attaching that as a drive to the VM. Signed-off-by: Alyssa Ross <hi@alyssa.is> --- v3: pass $@ to mount-flatpak rather than each individual argument. v2: https://spectrum-os.org/lists/archives/spectrum-devel/20251124195921.24441-1... host/rootfs/default.nix | 10 +++--- host/rootfs/file-list.mk | 1 + host/rootfs/image/usr/bin/run-flatpak | 51 +++++++++++++++++++++++++++ 3 files changed, 58 insertions(+), 4 deletions(-) create mode 100755 host/rootfs/image/usr/bin/run-flatpak diff --git a/host/rootfs/default.nix b/host/rootfs/default.nix index 941c04e..c93a06b 100644 --- a/host/rootfs/default.nix +++ b/host/rootfs/default.nix @@ -11,8 +11,9 @@ pkgsStatic.callPackage ( { spectrum-host-tools , lib, stdenvNoCC, nixos, runCommand, writeClosure, erofs-utils, s6-rc , busybox, cloud-hypervisor, cryptsetup, dbus, execline, inkscape -, iproute2, inotify-tools, jq, mdevd, s6, s6-linux-init, socat -, util-linuxMinimal, virtiofsd, xorg, xdg-desktop-portal-spectrum-host +, iproute2, inotify-tools, jq, mdevd, mount-flatpak, s6, s6-linux-init +, socat, util-linuxMinimal, virtiofsd, xorg +, xdg-desktop-portal-spectrum-host }: let @@ -34,8 +35,9 @@ let packages = [ cloud-hypervisor cryptsetup dbus execline inotify-tools iproute2 - jq mdevd s6 s6-linux-init s6-rc socat spectrum-host-tools - util-linuxMinimal virtiofsd xdg-desktop-portal-spectrum-host + jq mdevd mount-flatpak s6 s6-linux-init s6-rc socat + spectrum-host-tools util-linuxMinimal virtiofsd + xdg-desktop-portal-spectrum-host (busybox.override { # Use a separate file as it is a bit too big. diff --git a/host/rootfs/file-list.mk b/host/rootfs/file-list.mk index 7625c54..67529c0 100644 --- a/host/rootfs/file-list.mk +++ b/host/rootfs/file-list.mk @@ -43,6 +43,7 @@ FILES = \ image/usr/bin/assign-devices \ image/usr/bin/create-vm-dependencies \ image/usr/bin/run-appimage \ + image/usr/bin/run-flatpak \ image/usr/bin/run-vmm \ image/usr/bin/vm-console \ image/usr/bin/vm-import \ diff --git a/host/rootfs/image/usr/bin/run-flatpak b/host/rootfs/image/usr/bin/run-flatpak new file mode 100755 index 0000000..f7b9bc4 --- /dev/null +++ b/host/rootfs/image/usr/bin/run-flatpak @@ -0,0 +1,51 @@ +#!/bin/execlineb -W +# SPDX-License-Identifier: EUPL-1.2+ +# SPDX-FileCopyrightText: 2024-2025 Alyssa Ross <hi@alyssa.is> + +backtick -E dir { mktemp -d /run/vm/by-id/XXXXXX } +backtick -E id { basename -- $dir } + +if { + elgetpositionals + + if { mkdir -p /run/configs/${id}/fs } + if { redirfd -w 1 /run/configs/${id}/fs/type echo flatpak } + if { cd /run/configs/${id}/fs mount-flatpak $@ } + if { + ln -s /usr/lib/spectrum/img/appvm/blk /usr/lib/spectrum/img/appvm/vmlinux + /run/configs/${id} + } + + if { ln -s /run/configs/${id} ${dir}/config } + + if { create-vm-dependencies $id } + + piperw 4 3 + background { + fdclose 3 + fdmove 0 4 + + # Wait for the VMM to be up, then start the VM. + if { redirfd -w 1 /dev/null head -1 } + vm-start $id + } + fdclose 4 + + foreground { run-vmm $id } +} + +if { s6-instance-delete -- /run/service/vm-services $id } + +if { + elglob -0 flatpak_dir_mounts /run/configs/${id}/fs/flatpak/*/*/*/*/* + forx -E mount { + ${dir}/fs/doc + /run/configs/${id}/fs/flatpak/repo/config + $flatpak_dir_mounts + /run/configs/${id}/fs/flatpak + ${dir}/fs/config + } + umount $mount +} + +rm -r $dir /run/configs/${id} -- 2.51.0
On 11/27/25 15:23, Alyssa Ross wrote:
I tried to build this with Meson, but pathrs depends on thiserror, which tries to read OUT_DIR, and support for setting that isn't currently in a Meson release, and requires nightly Rust, so build with Cargo for now and we can revisit that later.
Link: https://github.com/mesonbuild/meson/pull/15148 Link: https://github.com/rust-lang/rust/issues/118372 Signed-off-by: Alyssa Ross <hi@alyssa.is> --- v3: Take the user data partition root and path to the Flatpak repository within it as separate parameters, to avoid calling Root::open() on an untrusted path. Suggested by Demi out of band. v2: https://spectrum-os.org/lists/archives/spectrum-devel/20251124194846.16338-1...
LICENSES/MPL-2.0.txt | 373 +++++++++++++++++++++++++ pkgs/default.nix | 1 + tools/mount-flatpak/Cargo.lock | 238 ++++++++++++++++ tools/mount-flatpak/Cargo.lock.license | 2 + tools/mount-flatpak/Cargo.toml | 11 + tools/mount-flatpak/config | 7 + tools/mount-flatpak/default.nix | 25 ++ tools/mount-flatpak/src/keyfile.rs | 189 +++++++++++++ tools/mount-flatpak/src/main.rs | 252 +++++++++++++++++ tools/mount-flatpak/src/metadata.rs | 19 ++ 10 files changed, 1117 insertions(+) create mode 100644 LICENSES/MPL-2.0.txt create mode 100644 tools/mount-flatpak/Cargo.lock create mode 100644 tools/mount-flatpak/Cargo.lock.license create mode 100644 tools/mount-flatpak/Cargo.toml create mode 100644 tools/mount-flatpak/config create mode 100644 tools/mount-flatpak/default.nix create mode 100644 tools/mount-flatpak/src/keyfile.rs create mode 100644 tools/mount-flatpak/src/main.rs create mode 100644 tools/mount-flatpak/src/metadata.rs
diff --git a/LICENSES/MPL-2.0.txt b/LICENSES/MPL-2.0.txt new file mode 100644 index 0000000..d0a1fa1 --- /dev/null +++ b/LICENSES/MPL-2.0.txt @@ -0,0 +1,373 @@ +Mozilla Public License Version 2.0 +================================== + +1. Definitions +-------------- + +1.1. "Contributor" + means each individual or legal entity that creates, contributes to + the creation of, or owns Covered Software. + +1.2. "Contributor Version" + means the combination of the Contributions of others (if any) used + by a Contributor and that particular Contributor's Contribution. + +1.3. "Contribution" + means Covered Software of a particular Contributor. + +1.4. "Covered Software" + means Source Code Form to which the initial Contributor has attached + the notice in Exhibit A, the Executable Form of such Source Code + Form, and Modifications of such Source Code Form, in each case + including portions thereof. + +1.5. "Incompatible With Secondary Licenses" + means + + (a) that the initial Contributor has attached the notice described + in Exhibit B to the Covered Software; or + + (b) that the Covered Software was made available under the terms of + version 1.1 or earlier of the License, but not also under the + terms of a Secondary License. + +1.6. "Executable Form" + means any form of the work other than Source Code Form. + +1.7. "Larger Work" + means a work that combines Covered Software with other material, in + a separate file or files, that is not Covered Software. + +1.8. "License" + means this document. + +1.9. "Licensable" + means having the right to grant, to the maximum extent possible, + whether at the time of the initial grant or subsequently, any and + all of the rights conveyed by this License. + +1.10. "Modifications" + means any of the following: + + (a) any file in Source Code Form that results from an addition to, + deletion from, or modification of the contents of Covered + Software; or + + (b) any new file in Source Code Form that contains any Covered + Software. + +1.11. "Patent Claims" of a Contributor + means any patent claim(s), including without limitation, method, + process, and apparatus claims, in any patent Licensable by such + Contributor that would be infringed, but for the grant of the + License, by the making, using, selling, offering for sale, having + made, import, or transfer of either its Contributions or its + Contributor Version. + +1.12. "Secondary License" + means either the GNU General Public License, Version 2.0, the GNU + Lesser General Public License, Version 2.1, the GNU Affero General + Public License, Version 3.0, or any later versions of those + licenses. + +1.13. "Source Code Form" + means the form of the work preferred for making modifications. + +1.14. "You" (or "Your") + means an individual or a legal entity exercising rights under this + License. For legal entities, "You" includes any entity that + controls, is controlled by, or is under common control with You. For + purposes of this definition, "control" means (a) the power, direct + or indirect, to cause the direction or management of such entity, + whether by contract or otherwise, or (b) ownership of more than + fifty percent (50%) of the outstanding shares or beneficial + ownership of such entity. + +2. License Grants and Conditions +-------------------------------- + +2.1. Grants + +Each Contributor hereby grants You a world-wide, royalty-free, +non-exclusive license: + +(a) under intellectual property rights (other than patent or trademark) + Licensable by such Contributor to use, reproduce, make available, + modify, display, perform, distribute, and otherwise exploit its + Contributions, either on an unmodified basis, with Modifications, or + as part of a Larger Work; and + +(b) under Patent Claims of such Contributor to make, use, sell, offer + for sale, have made, import, and otherwise transfer either its + Contributions or its Contributor Version. + +2.2. Effective Date + +The licenses granted in Section 2.1 with respect to any Contribution +become effective for each Contribution on the date the Contributor first +distributes such Contribution. + +2.3. Limitations on Grant Scope + +The licenses granted in this Section 2 are the only rights granted under +this License. No additional rights or licenses will be implied from the +distribution or licensing of Covered Software under this License. +Notwithstanding Section 2.1(b) above, no patent license is granted by a +Contributor: + +(a) for any code that a Contributor has removed from Covered Software; + or + +(b) for infringements caused by: (i) Your and any other third party's + modifications of Covered Software, or (ii) the combination of its + Contributions with other software (except as part of its Contributor + Version); or + +(c) under Patent Claims infringed by Covered Software in the absence of + its Contributions. + +This License does not grant any rights in the trademarks, service marks, +or logos of any Contributor (except as may be necessary to comply with +the notice requirements in Section 3.4). + +2.4. Subsequent Licenses + +No Contributor makes additional grants as a result of Your choice to +distribute the Covered Software under a subsequent version of this +License (see Section 10.2) or under the terms of a Secondary License (if +permitted under the terms of Section 3.3). + +2.5. Representation + +Each Contributor represents that the Contributor believes its +Contributions are its original creation(s) or it has sufficient rights +to grant the rights to its Contributions conveyed by this License. + +2.6. Fair Use + +This License is not intended to limit any rights You have under +applicable copyright doctrines of fair use, fair dealing, or other +equivalents. + +2.7. Conditions + +Sections 3.1, 3.2, 3.3, and 3.4 are conditions of the licenses granted +in Section 2.1. + +3. Responsibilities +------------------- + +3.1. Distribution of Source Form + +All distribution of Covered Software in Source Code Form, including any +Modifications that You create or to which You contribute, must be under +the terms of this License. You must inform recipients that the Source +Code Form of the Covered Software is governed by the terms of this +License, and how they can obtain a copy of this License. You may not +attempt to alter or restrict the recipients' rights in the Source Code +Form. + +3.2. Distribution of Executable Form + +If You distribute Covered Software in Executable Form then: + +(a) such Covered Software must also be made available in Source Code + Form, as described in Section 3.1, and You must inform recipients of + the Executable Form how they can obtain a copy of such Source Code + Form by reasonable means in a timely manner, at a charge no more + than the cost of distribution to the recipient; and + +(b) You may distribute such Executable Form under the terms of this + License, or sublicense it under different terms, provided that the + license for the Executable Form does not attempt to limit or alter + the recipients' rights in the Source Code Form under this License. + +3.3. Distribution of a Larger Work + +You may create and distribute a Larger Work under terms of Your choice, +provided that You also comply with the requirements of this License for +the Covered Software. If the Larger Work is a combination of Covered +Software with a work governed by one or more Secondary Licenses, and the +Covered Software is not Incompatible With Secondary Licenses, this +License permits You to additionally distribute such Covered Software +under the terms of such Secondary License(s), so that the recipient of +the Larger Work may, at their option, further distribute the Covered +Software under the terms of either this License or such Secondary +License(s). + +3.4. Notices + +You may not remove or alter the substance of any license notices +(including copyright notices, patent notices, disclaimers of warranty, +or limitations of liability) contained within the Source Code Form of +the Covered Software, except that You may alter any license notices to +the extent required to remedy known factual inaccuracies. + +3.5. Application of Additional Terms + +You may choose to offer, and to charge a fee for, warranty, support, +indemnity or liability obligations to one or more recipients of Covered +Software. However, You may do so only on Your own behalf, and not on +behalf of any Contributor. You must make it absolutely clear that any +such warranty, support, indemnity, or liability obligation is offered by +You alone, and You hereby agree to indemnify every Contributor for any +liability incurred by such Contributor as a result of warranty, support, +indemnity or liability terms You offer. You may include additional +disclaimers of warranty and limitations of liability specific to any +jurisdiction. + +4. Inability to Comply Due to Statute or Regulation +--------------------------------------------------- + +If it is impossible for You to comply with any of the terms of this +License with respect to some or all of the Covered Software due to +statute, judicial order, or regulation then You must: (a) comply with +the terms of this License to the maximum extent possible; and (b) +describe the limitations and the code they affect. Such description must +be placed in a text file included with all distributions of the Covered +Software under this License. Except to the extent prohibited by statute +or regulation, such description must be sufficiently detailed for a +recipient of ordinary skill to be able to understand it. + +5. Termination +-------------- + +5.1. The rights granted under this License will terminate automatically +if You fail to comply with any of its terms. However, if You become +compliant, then the rights granted under this License from a particular +Contributor are reinstated (a) provisionally, unless and until such +Contributor explicitly and finally terminates Your grants, and (b) on an +ongoing basis, if such Contributor fails to notify You of the +non-compliance by some reasonable means prior to 60 days after You have +come back into compliance. Moreover, Your grants from a particular +Contributor are reinstated on an ongoing basis if such Contributor +notifies You of the non-compliance by some reasonable means, this is the +first time You have received notice of non-compliance with this License +from such Contributor, and You become compliant prior to 30 days after +Your receipt of the notice. + +5.2. If You initiate litigation against any entity by asserting a patent +infringement claim (excluding declaratory judgment actions, +counter-claims, and cross-claims) alleging that a Contributor Version +directly or indirectly infringes any patent, then the rights granted to +You by any and all Contributors for the Covered Software under Section +2.1 of this License shall terminate. + +5.3. In the event of termination under Sections 5.1 or 5.2 above, all +end user license agreements (excluding distributors and resellers) which +have been validly granted by You or Your distributors under this License +prior to termination shall survive termination. + +************************************************************************ +* * +* 6. Disclaimer of Warranty * +* ------------------------- * +* * +* Covered Software is provided under this License on an "as is" * +* basis, without warranty of any kind, either expressed, implied, or * +* statutory, including, without limitation, warranties that the * +* Covered Software is free of defects, merchantable, fit for a * +* particular purpose or non-infringing. The entire risk as to the * +* quality and performance of the Covered Software is with You. * +* Should any Covered Software prove defective in any respect, You * +* (not any Contributor) assume the cost of any necessary servicing, * +* repair, or correction. This disclaimer of warranty constitutes an * +* essential part of this License. No use of any Covered Software is * +* authorized under this License except under this disclaimer. * +* * +************************************************************************ + +************************************************************************ +* * +* 7. Limitation of Liability * +* -------------------------- * +* * +* Under no circumstances and under no legal theory, whether tort * +* (including negligence), contract, or otherwise, shall any * +* Contributor, or anyone who distributes Covered Software as * +* permitted above, be liable to You for any direct, indirect, * +* special, incidental, or consequential damages of any character * +* including, without limitation, damages for lost profits, loss of * +* goodwill, work stoppage, computer failure or malfunction, or any * +* and all other commercial damages or losses, even if such party * +* shall have been informed of the possibility of such damages. This * +* limitation of liability shall not apply to liability for death or * +* personal injury resulting from such party's negligence to the * +* extent applicable law prohibits such limitation. Some * +* jurisdictions do not allow the exclusion or limitation of * +* incidental or consequential damages, so this exclusion and * +* limitation may not apply to You. * +* * +************************************************************************ + +8. Litigation +------------- + +Any litigation relating to this License may be brought only in the +courts of a jurisdiction where the defendant maintains its principal +place of business and such litigation shall be governed by laws of that +jurisdiction, without reference to its conflict-of-law provisions. +Nothing in this Section shall prevent a party's ability to bring +cross-claims or counter-claims. + +9. Miscellaneous +---------------- + +This License represents the complete agreement concerning the subject +matter hereof. If any provision of this License is held to be +unenforceable, such provision shall be reformed only to the extent +necessary to make it enforceable. Any law or regulation which provides +that the language of a contract shall be construed against the drafter +shall not be used to construe this License against a Contributor. + +10. Versions of the License +--------------------------- + +10.1. New Versions + +Mozilla Foundation is the license steward. Except as provided in Section +10.3, no one other than the license steward has the right to modify or +publish new versions of this License. Each version will be given a +distinguishing version number. + +10.2. Effect of New Versions + +You may distribute the Covered Software under the terms of the version +of the License under which You originally received the Covered Software, +or under the terms of any subsequent version published by the license +steward. + +10.3. Modified Versions + +If you create software not governed by this License, and you want to +create a new license for such software, you may create and use a +modified version of this License if you rename the license and remove +any references to the name of the license steward (except to note that +such modified license differs from this License). + +10.4. Distributing Source Code Form that is Incompatible With Secondary +Licenses + +If You choose to distribute Source Code Form that is Incompatible With +Secondary Licenses under the terms of this version of the License, the +notice described in Exhibit B of this License must be attached. + +Exhibit A - Source Code Form License Notice +------------------------------------------- + + 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/. + +If it is not possible or desirable to put the notice in a particular +file, then You may include the notice in a location (such as a LICENSE +file in a relevant directory) where a recipient would be likely to look +for such a notice. + +You may add additional accurate notices of copyright ownership. + +Exhibit B - "Incompatible With Secondary Licenses" Notice +--------------------------------------------------------- + + This Source Code Form is "Incompatible With Secondary Licenses", as + defined by the Mozilla Public License, v. 2.0. diff --git a/pkgs/default.nix b/pkgs/default.nix index cc60228..6829185 100644 --- a/pkgs/default.nix +++ b/pkgs/default.nix @@ -36,6 +36,7 @@ let path: (import path { inherit (self) callPackage; }).override;
rootfs = self.callSpectrumPackage ../host/rootfs {}; + mount-flatpak = self.callSpectrumPackage ../tools/mount-flatpak {}; spectrum-build-tools = self.callSpectrumPackage ../tools { appSupport = false; buildSupport = true; diff --git a/tools/mount-flatpak/Cargo.lock b/tools/mount-flatpak/Cargo.lock new file mode 100644 index 0000000..8cb5663 --- /dev/null +++ b/tools/mount-flatpak/Cargo.lock @@ -0,0 +1,238 @@ +# This file is automatically @generated by Cargo. +# It is not intended for manual editing. +version = 4 + +[[package]] +name = "bitflags" +version = "2.10.0" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "812e12b5285cc515a9c72a5c1d3b6d46a19dac5acfef5265968c166106e31dd3" + +[[package]] +name = "cfg-if" +version = "1.0.4" +source = "registry+https://github.com/rust-lang/crates.io-index" +checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801" + +[[package]] +name = "either" +version = "1.15.0" +source = 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"f17a85883d4e6d00e8a97c586de764dabcc06133f7f1d55dce5cdc070ad7fe59" diff --git a/tools/mount-flatpak/Cargo.lock.license b/tools/mount-flatpak/Cargo.lock.license new file mode 100644 index 0000000..d705e97 --- /dev/null +++ b/tools/mount-flatpak/Cargo.lock.license @@ -0,0 +1,2 @@ +SPDX-License-Identifier: CC0-1.0 +SPDX-FileCopyrightText: 2024 Alyssa Ross <hi@alyssa.is> diff --git a/tools/mount-flatpak/Cargo.toml b/tools/mount-flatpak/Cargo.toml new file mode 100644 index 0000000..670be2f --- /dev/null +++ b/tools/mount-flatpak/Cargo.toml @@ -0,0 +1,11 @@ +# SPDX-License-Identifier: CC0-1.0 +# SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +[package] +name = "mount-flatpak" +edition = "2024" + +[dependencies] +libc = "0.2.177" +pathrs = "0.2.1" +rustix = "1.1.2" diff --git a/tools/mount-flatpak/config b/tools/mount-flatpak/config new file mode 100644 index 0000000..b3c2bee --- /dev/null +++ b/tools/mount-flatpak/config @@ -0,0 +1,7 @@ +# SPDX-License-Identifier: CC0-1.0 +# SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +[core] +repo_version=1 +mode=bare-user-only +min-free-space-size=500MB diff --git a/tools/mount-flatpak/default.nix b/tools/mount-flatpak/default.nix new file mode 100644 index 0000000..f364fd7 --- /dev/null +++ b/tools/mount-flatpak/default.nix @@ -0,0 +1,25 @@ +# SPDX-FileCopyrightText: 2024-2025 Alyssa Ross <hi@alyssa.is> +# SPDX-License-Identifier: MIT + +import ../../lib/call-package.nix ( +{ src, lib, rustPlatform }: + +rustPlatform.buildRustPackage { + name = "mount-flatpak"; + + src = lib.fileset.toSource { + root = ../..; + fileset = lib.fileset.intersection src ./.; + }; + sourceRoot = "source/tools/mount-flatpak"; + + cargoLock.lockFile = ./Cargo.lock; + + env = { + MOUNT_FLATPAK_CONFIG_PATH = "${placeholder "out"}/share/spectrum/flatpak-config"; + }; + + postInstall = '' + install -Dm 0755 config $MOUNT_FLATPAK_CONFIG_PATH + ''; +}) (_: {}) diff --git a/tools/mount-flatpak/src/keyfile.rs b/tools/mount-flatpak/src/keyfile.rs new file mode 100644 index 0000000..fa746b3 --- /dev/null +++ b/tools/mount-flatpak/src/keyfile.rs @@ -0,0 +1,189 @@ +// Copyright 2021 System76 <info@system76.com> +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> +// SPDX-License-Identifier: MPL-2.0 + +// Adapted from freedesktop-desktop-entry 0.7.19. + +use std::collections::BTreeMap; +use std::fmt::{self, Display, Formatter}; + +type Group = BTreeMap<String, String>; + +#[derive(Debug)] +pub enum DecodeError { + KeyValueWithoutAGroup, + InvalidKey, + InvalidValue, +} + +impl Display for DecodeError { + fn fmt(&self, f: &mut Formatter) -> fmt::Result { + match self { + Self::KeyValueWithoutAGroup => write!(f, "key/value without a group"), + Self::InvalidKey => write!(f, "invalid key"), + Self::InvalidValue => write!(f, "invalid value"), + } + } +} + +pub fn parse(input: &str) -> Result<BTreeMap<String, Group>, DecodeError> { + let mut groups = BTreeMap::default(); + let mut active_group: Option<ActiveGroup> = None; + let mut active_keys: Option<ActiveKeys> = None; + + for line in input.lines() { + process_line(line, &mut groups, &mut active_group, &mut active_keys)?; + } + + if let Some(active_keys) = active_keys.take() { + match &mut active_group { + Some(active_group) => { + active_group + .group + .insert(active_keys.key_name, active_keys.value); + } + None => return Err(DecodeError::KeyValueWithoutAGroup), + } + } + + if let Some(mut group) = active_group.take() { + groups + .entry(group.group_name) + .or_default() + .append(&mut group.group); + } + + Ok(groups) +} + +struct ActiveGroup { + group_name: String, + group: Group, +} + +struct ActiveKeys { + key_name: String, + value: String, +} + +#[inline(never)] +fn process_line( + line: &str, + groups: &mut BTreeMap<String, Group>, + active_group: &mut Option<ActiveGroup>, + active_keys: &mut Option<ActiveKeys>, +) -> Result<(), DecodeError> { + if line.trim().is_empty() || line.starts_with('#') { + return Ok(()); + } + + let line_bytes = line.as_bytes(); + + // if group + if line_bytes[0] == b'[' { + if let Some(end) = line_bytes[1..].iter().rposition(|&b| b == b']') { + let group_name = &line[1..end + 1]; + + if let Some(active_keys) = active_keys.take() { + match active_group { + Some(active_group) => { + active_group + .group + .insert(active_keys.key_name, active_keys.value); + } + None => return Err(DecodeError::KeyValueWithoutAGroup), + } + } + + if let Some(mut group) = active_group.take() { + groups + .entry(group.group_name) + .or_default() + .append(&mut group.group); + } + + active_group.replace(ActiveGroup { + group_name: group_name.to_string(), + group: Group::default(), + }); + } + } + // else, if value + else if let Some(delimiter) = line_bytes.iter().position(|&b| b == b'=') { + let key = &line[..delimiter]; + let value = format_value(&line[delimiter + 1..])?; + + if key.is_empty() { + return Err(DecodeError::InvalidKey); + } + + if let Some(active_keys) = active_keys.take() { + match active_group { + Some(active_group) => { + active_group + .group + .insert(active_keys.key_name, active_keys.value); + } + None => return Err(DecodeError::KeyValueWithoutAGroup), + } + } + active_keys.replace(ActiveKeys { + key_name: key.trim().to_string(), + value, + }); + } + Ok(()) +} + +// https://specifications.freedesktop.org/desktop-entry-spec/latest/value-types... +#[inline] +fn format_value(input: &str) -> Result<String, DecodeError> { + let input = if let Some(input) = input.strip_prefix(" ") { + input + } else { + input + }; + + let mut res = String::with_capacity(input.len()); + + let mut last: usize = 0; + + for (i, v) in input.as_bytes().iter().enumerate() { + if *v != b'\\' { + continue; + } + + // edge case for // + if last > i { + continue; + } + + // when there is an \ at the end + if input.len() <= i + 1 { + return Err(DecodeError::InvalidValue); + } + + if last < i { + res.push_str(&input[last..i]); + } + + last = i + 2; + + match input.as_bytes()[i + 1] { + b's' => res.push(' '), + b'n' => res.push('\n'), + b't' => res.push('\t'), + b'r' => res.push('\r'), + b'\\' => res.push('\\'), + _ => { + return Err(DecodeError::InvalidValue); + } + } + } + + if last < input.len() { + res.push_str(&input[last..input.len()]); + } + + Ok(res) +} diff --git a/tools/mount-flatpak/src/main.rs b/tools/mount-flatpak/src/main.rs new file mode 100644 index 0000000..fd2f74f --- /dev/null +++ b/tools/mount-flatpak/src/main.rs @@ -0,0 +1,252 @@ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> +// SPDX-License-Identifier: EUPL-1.2+ + +mod keyfile; +mod metadata; + +use std::borrow::Cow; +use std::env::{ArgsOs, args_os}; +use std::ffi::OsStr; +use std::io; +use std::os::unix::prelude::*; +use std::path::{Path, PathBuf}; +use std::process::exit; + +use pathrs::Root; +use pathrs::flags::{OpenFlags, ResolverFlags}; +use rustix::fs::{CWD, FileType, fstat}; +use rustix::mount::{MoveMountFlags, OpenTreeFlags, move_mount, open_tree}; + +use metadata::extract_runtime; + +fn ex_usage() -> ! { + eprintln!("Usage: mount-flatpak installation app"); + exit(1); +}
Stale usage message.
+fn run(mut args: ArgsOs) -> Result<(), String> { + let Some(user_data_path) = args.next().map(PathBuf::from) else { + ex_usage(); + };
This should be an absolute path, as the working directory isn't one that the user should be caring about.
+ let Some(installation_path) = args.next().map(PathBuf::from) else { + ex_usage(); + }; + let Some(app) = args.next() else { + ex_usage(); + };
I recommend checking that 'app' is not empty, '.' or '..' and does not contain '/'.
+ if args.next().is_some() { + ex_usage(); + } + + let mut source_installation_dir = Root::open(&user_data_path) + .map_err(|e| format!("opening source flatpak installation: {e}"))?;> + + source_installation_dir.set_resolver_flags(ResolverFlags::NO_SYMLINKS); + + std::fs::create_dir("flatpak") + .map_err(|e| format!("creating target flatpak installation: {e}"))?;
This code looks good.
+ let target_installation_dir = open_tree( + CWD, + "flatpak", + OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE,
Missing AT_SYMLINK_NOFOLLOW unless it is is implied.
+ ) + .map_err(|e| format!("opening target flatpak installation: {e}"))?; + let mut target_installation_dir = Root::from_fd(target_installation_dir); + target_installation_dir.set_resolver_flags(ResolverFlags::NO_SYMLINKS);
Is NO_XDEV implied? It's not supported in the API but it would be useful to check.
+ let mut full_app_path = installation_path.join("app"); + full_app_path.push(&app); + full_app_path.push("current"); + let arch_and_branch = source_installation_dir + .readlink(&full_app_path) + .map_err(|e| format!("reading current app arch and branch: {e}"))?;
This is somewhat hard to understand. I recommend a big comment at the start of the file explaining the structure of the source directory, which is: VM's directory/ Installation root/ app/ App ID/ current -> arch/branch arch/ branch/ active -> actual commit hash (64 bytes lowercase hex) commit hash metadata (contains runtime info) runtime/ Runtime ID/ arch/ branch/ active -> actual commit hash (64 bytes lowercase hex) commit hash As well as that of the target directory, which I'm not sure about.
+ let mut components = arch_and_branch.components(); + let arch = components.next().unwrap().as_os_str(); + let branch = components.as_path().as_os_str(); + if branch.is_empty() { + return Err("can't infer branch from \"current\" link".to_string()); + } + + full_app_path.pop(); + full_app_path.push(&arch_and_branch); + full_app_path.push("active"); + let commit = source_installation_dir + .readlink(&full_app_path) + .map_err(|e| format!("reading active app commit: {e}"))? + .into_os_string(); + + full_app_path.pop(); + full_app_path.push(&commit); + let source_app_dir = source_installation_dir + .resolve(&full_app_path) + .map_err(|e| format!("opening source app directory: {e}"))?; + + let metadata = source_installation_dir + .resolve(full_app_path.join("metadata")) + .map_err(|e| format!("resolving app metadata: {e}"))?; + + let metadata_stat = + fstat(&metadata).map_err(|e| format!("checking app metadata is a regular file: {e}"))?; + let metadata_type = FileType::from_raw_mode(metadata_stat.st_mode); + if !metadata_type.is_file() { + let e = format!("type of app metadata is {metadata_type:?}, not RegularFile"); + return Err(e); + } + let metadata = metadata + .reopen(OpenFlags::O_RDONLY) + .map_err(|e| format!("opening app metadata: {e}"))?; + + let runtime = + extract_runtime(metadata).map_err(|e| format!("reading runtime from metadata: {e}"))?; + + let mut full_runtime_path = installation_path.join("runtime"); + full_runtime_path.push(runtime); + full_runtime_path.push("active"); + let runtime_commit = source_installation_dir + .readlink(&full_runtime_path) + .map_err(|e| format!("reading active runtime commit: {e}"))? + .into_os_string(); + + full_runtime_path.pop(); + full_runtime_path.push(&runtime_commit); + let source_runtime_dir = source_installation_dir + .resolve(&full_runtime_path) + .map_err(|e| format!("opening source runtime directory: {e}"))?; + + let target_app_dir = target_installation_dir + .mkdir_all(&full_app_path, &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating target app directory: {e}"))?; + let target_runtime_dir = target_installation_dir + .mkdir_all(&full_runtime_path, &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating target runtime directory: {e}"))?; + + let source_app_tree = open_tree( + &source_app_dir, + "", + OpenTreeFlags::AT_EMPTY_PATH + | OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE, + ) + .map_err(|e| format!("cloning source app tree: {e}"))?; + let source_runtime_tree = open_tree( + &source_runtime_dir, + "", + OpenTreeFlags::AT_EMPTY_PATH + | OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE, + ) + .map_err(|e| format!("cloning source runtime tree: {e}"))?; + + move_mount( + source_app_tree, + "", + target_app_dir, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting app directory: {e}"))?; + move_mount( + source_runtime_tree, + "", + target_runtime_dir, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting runtime directory: {e}"))?; + + target_installation_dir + .mkdir_all("repo/objects", &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating repo/objects: {e}"))?; + target_installation_dir + .mkdir_all("repo/tmp/cache", &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating repo/tmp/cache: {e}"))?; + let config_target = target_installation_dir + .create_file( + "repo/config", + OpenFlags::O_WRONLY | OpenFlags::O_CLOEXEC, + &PermissionsExt::from_mode(0o700), + ) + .map_err(|e| format!("creating repo/config: {e}"))?; + let config_source_path = env!("MOUNT_FLATPAK_CONFIG_PATH");
This should always be an absolute path, and it might be good to assert that.
+ let config_source = open_tree( + CWD, + config_source_path, + OpenTreeFlags::OPEN_TREE_CLONE | OpenTreeFlags::OPEN_TREE_CLOEXEC, + ) + .map_err(|e| format!("opening {config_source_path}: {e}"))?; + move_mount( + config_source, + "", + config_target, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting config: {e}"))?; + + let mut attr = libc::mount_attr { + attr_clr: libc::MOUNT_ATTR_NOSYMFOLLOW, + attr_set: libc::MOUNT_ATTR_RDONLY | libc::MOUNT_ATTR_NODEV, + propagation: 0, + userns_fd: 0, + };
Propagation should likely be set to MS_SLAVE. (Yeah, I know, terrible name.) attr_set should also include MOUNT_ATTR_NOEXEC as well as the host has no business executing anything there.
+ let empty = b"\0"; + // SAFETY: we pass a valid FD, and a valid mutable pointer with the correct size. + unsafe { + let r = libc::syscall( + libc::SYS_mount_setattr, + target_installation_dir.as_fd(), + empty.as_ptr() as *const libc::c_char, + (libc::AT_EMPTY_PATH | libc::AT_RECURSIVE) as libc::c_uint, + &mut attr as *mut libc::mount_attr, + size_of::<libc::mount_attr>() as libc::size_t, + );
All of the non-pointer arguments need to be cast to libc::c_long or (equivalently and possibly better) core::ffi::c_long.
+ if r == -1 { + return Err(format!( + "setting target mount attributes: {}", + io::Error::last_os_error() + )); + } + } + move_mount( + target_installation_dir, + "", + CWD, + "flatpak", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH, + ) + .map_err(|e| format!("mounting target installation dir: {e}"))?; + + std::fs::create_dir("params").map_err(|e| format!("creating params directory: {e}"))?; + std::fs::write("params/id", app.as_bytes()).map_err(|e| format!("writing params/id: {e}"))?; + std::fs::write("params/commit", commit.as_bytes()) + .map_err(|e| format!("writing params/commit: {e}"))?; + std::fs::write("params/arch", arch.as_bytes()) + .map_err(|e| format!("writing params/arch: {e}"))?; + std::fs::write("params/branch", branch.as_bytes()) + .map_err(|e| format!("writing params/branch: {e}"))?; + std::fs::write("params/runtime-commit", runtime_commit.as_bytes()) + .map_err(|e| format!("writing params/runtime-commit: {e}"))?; + + Ok(()) +} + +fn main() { + let mut args = args_os(); + + let prog_name = args + .next() + .as_ref() + .map(Path::new) + .and_then(Path::file_name) + .map_or(Cow::Borrowed("mount-flatpak"), OsStr::to_string_lossy) + .into_owned(); + + if let Err(e) = run(args) { + eprintln!("{prog_name}: {e}"); + exit(1); + } +} diff --git a/tools/mount-flatpak/src/metadata.rs b/tools/mount-flatpak/src/metadata.rs new file mode 100644 index 0000000..dfc05b1 --- /dev/null +++ b/tools/mount-flatpak/src/metadata.rs @@ -0,0 +1,19 @@ +// SPDX-License-Identifier: EUPL-1.2+ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +use std::fs::File; +use std::io::read_to_string; + +use crate::keyfile::parse; + +pub fn extract_runtime(mut metadata: File) -> Result<String, String> { + let metadata = read_to_string(&mut metadata).map_err(|e| e.to_string())?;
Missing limit on the size of the file to prevent unbounded memory allocation.
+ let group = parse(&metadata).map_err(|e| e.to_string())?; + let application = group + .get("Application") + .ok_or_else(|| "Application group missing".to_string())?; + Ok(application + .get("runtime") + .ok_or_else(|| "runtime property missing".to_string())? + .clone()) +}
base-commit: 4200cea7eb31f5b8d35bf4c00b879aa25cf1fb90 -- Sincerely, Demi Marie Obenour (she/her/hers)
Demi Marie Obenour <demiobenour@gmail.com> writes:
On 11/27/25 15:23, Alyssa Ross wrote:
diff --git a/tools/mount-flatpak/src/main.rs b/tools/mount-flatpak/src/main.rs new file mode 100644 index 0000000..fd2f74f --- /dev/null +++ b/tools/mount-flatpak/src/main.rs @@ -0,0 +1,252 @@ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> +// SPDX-License-Identifier: EUPL-1.2+ + +mod keyfile; +mod metadata; + +use std::borrow::Cow; +use std::env::{ArgsOs, args_os}; +use std::ffi::OsStr; +use std::io; +use std::os::unix::prelude::*; +use std::path::{Path, PathBuf}; +use std::process::exit; + +use pathrs::Root; +use pathrs::flags::{OpenFlags, ResolverFlags}; +use rustix::fs::{CWD, FileType, fstat}; +use rustix::mount::{MoveMountFlags, OpenTreeFlags, move_mount, open_tree}; + +use metadata::extract_runtime; + +fn ex_usage() -> ! { + eprintln!("Usage: mount-flatpak installation app"); + exit(1); +}
Stale usage message.
Will fix.
+fn run(mut args: ArgsOs) -> Result<(), String> { + let Some(user_data_path) = args.next().map(PathBuf::from) else { + ex_usage(); + };
This should be an absolute path, as the working directory isn't one that the user should be caring about.
I don't see any reason to restrict the user like that.
+ let Some(installation_path) = args.next().map(PathBuf::from) else { + ex_usage(); + }; + let Some(app) = args.next() else { + ex_usage(); + };
I recommend checking that 'app' is not empty, '.' or '..' and does not contain '/'.
I think this is a sign we really need to be using the flatpak installation as a root. We need to be protecting *systematically* against escapes from the flatpak directory to elsewhere on the user data partition, because that's where all the interesting data is. This comment[1] gives me the impression that it we should be okay opening a root for the user data partition, resolving the installation path inside the user partition, and creating a new root from that, to be used for everything within it. (We don't need to go any more granular than that, because it never makes sense for individual subdirectories of the Flatpak repository to be specifically writable by a VM, I think. So we assume that whatever writes the Flatpak repository already has access to the whole repository, and is not interested in tricking the host to do things to it that it could have just directly done itself.) [1]: https://github.com/cyphar/libpathrs/issues/26#issuecomment-586382681
+ let target_installation_dir = open_tree( + CWD, + "flatpak", + OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE,
Missing AT_SYMLINK_NOFOLLOW unless it is is implied.
We rely on nothing malicious being able to mess with the target directory while we're running, and we do not create flatpak as a symlink.
+ ) + .map_err(|e| format!("opening target flatpak installation: {e}"))?; + let mut target_installation_dir = Root::from_fd(target_installation_dir); + target_installation_dir.set_resolver_flags(ResolverFlags::NO_SYMLINKS);
Is NO_XDEV implied? It's not supported in the API but it would be useful to check.
It is not implied, but there's no way to set it either.
+ let mut full_app_path = installation_path.join("app"); + full_app_path.push(&app); + full_app_path.push("current"); + let arch_and_branch = source_installation_dir + .readlink(&full_app_path) + .map_err(|e| format!("reading current app arch and branch: {e}"))?;
This is somewhat hard to understand. I recommend a big comment at the start of the file explaining the structure of the source directory, which is:
VM's directory/ Installation root/ app/ App ID/ current -> arch/branch arch/ branch/ active -> actual commit hash (64 bytes lowercase hex) commit hash metadata (contains runtime info) runtime/ Runtime ID/ arch/ branch/ active -> actual commit hash (64 bytes lowercase hex) commit hash
As well as that of the target directory, which I'm not sure about.
I can do that. (The target directory is just an installation with a single app and single runtime installed.)
+ let mut components = arch_and_branch.components(); + let arch = components.next().unwrap().as_os_str(); + let branch = components.as_path().as_os_str(); + if branch.is_empty() { + return Err("can't infer branch from \"current\" link".to_string()); + } + + full_app_path.pop(); + full_app_path.push(&arch_and_branch); + full_app_path.push("active"); + let commit = source_installation_dir + .readlink(&full_app_path) + .map_err(|e| format!("reading active app commit: {e}"))? + .into_os_string(); + + full_app_path.pop(); + full_app_path.push(&commit); + let source_app_dir = source_installation_dir + .resolve(&full_app_path) + .map_err(|e| format!("opening source app directory: {e}"))?; + + let metadata = source_installation_dir + .resolve(full_app_path.join("metadata")) + .map_err(|e| format!("resolving app metadata: {e}"))?; + + let metadata_stat = + fstat(&metadata).map_err(|e| format!("checking app metadata is a regular file: {e}"))?; + let metadata_type = FileType::from_raw_mode(metadata_stat.st_mode); + if !metadata_type.is_file() { + let e = format!("type of app metadata is {metadata_type:?}, not RegularFile"); + return Err(e); + } + let metadata = metadata + .reopen(OpenFlags::O_RDONLY) + .map_err(|e| format!("opening app metadata: {e}"))?; + + let runtime = + extract_runtime(metadata).map_err(|e| format!("reading runtime from metadata: {e}"))?; + + let mut full_runtime_path = installation_path.join("runtime"); + full_runtime_path.push(runtime); + full_runtime_path.push("active"); + let runtime_commit = source_installation_dir + .readlink(&full_runtime_path) + .map_err(|e| format!("reading active runtime commit: {e}"))? + .into_os_string(); + + full_runtime_path.pop(); + full_runtime_path.push(&runtime_commit); + let source_runtime_dir = source_installation_dir + .resolve(&full_runtime_path) + .map_err(|e| format!("opening source runtime directory: {e}"))?; + + let target_app_dir = target_installation_dir + .mkdir_all(&full_app_path, &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating target app directory: {e}"))?; + let target_runtime_dir = target_installation_dir + .mkdir_all(&full_runtime_path, &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating target runtime directory: {e}"))?; + + let source_app_tree = open_tree( + &source_app_dir, + "", + OpenTreeFlags::AT_EMPTY_PATH + | OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE, + ) + .map_err(|e| format!("cloning source app tree: {e}"))?; + let source_runtime_tree = open_tree( + &source_runtime_dir, + "", + OpenTreeFlags::AT_EMPTY_PATH + | OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE, + ) + .map_err(|e| format!("cloning source runtime tree: {e}"))?; + + move_mount( + source_app_tree, + "", + target_app_dir, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting app directory: {e}"))?; + move_mount( + source_runtime_tree, + "", + target_runtime_dir, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting runtime directory: {e}"))?; + + target_installation_dir + .mkdir_all("repo/objects", &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating repo/objects: {e}"))?; + target_installation_dir + .mkdir_all("repo/tmp/cache", &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating repo/tmp/cache: {e}"))?; + let config_target = target_installation_dir + .create_file( + "repo/config", + OpenFlags::O_WRONLY | OpenFlags::O_CLOEXEC, + &PermissionsExt::from_mode(0o700), + ) + .map_err(|e| format!("creating repo/config: {e}"))?; + let config_source_path = env!("MOUNT_FLATPAK_CONFIG_PATH");
This should always be an absolute path, and it might be good to assert that.
str::contains is not const, so it's not possible to do this in the obvious way, but it's also not critical to validate a compile-time constant we know we're always setting correctly. Would consider a patch.
+ let config_source = open_tree( + CWD, + config_source_path, + OpenTreeFlags::OPEN_TREE_CLONE | OpenTreeFlags::OPEN_TREE_CLOEXEC, + ) + .map_err(|e| format!("opening {config_source_path}: {e}"))?; + move_mount( + config_source, + "", + config_target, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting config: {e}"))?; + + let mut attr = libc::mount_attr { + attr_clr: libc::MOUNT_ATTR_NOSYMFOLLOW, + attr_set: libc::MOUNT_ATTR_RDONLY | libc::MOUNT_ATTR_NODEV, + propagation: 0, + userns_fd: 0, + };
Propagation should likely be set to MS_SLAVE. (Yeah, I know, terrible name.) attr_set should also include MOUNT_ATTR_NOEXEC as well as the host has no business executing anything there.
The host has no business executing anything at all from the whole user data partition, so this is not the place to set that. There's no reason this mount _in particular_ needs the flag set that doesn't apply to the whole partition this mount's flags are inherited from.
+ let empty = b"\0"; + // SAFETY: we pass a valid FD, and a valid mutable pointer with the correct size. + unsafe { + let r = libc::syscall( + libc::SYS_mount_setattr, + target_installation_dir.as_fd(), + empty.as_ptr() as *const libc::c_char, + (libc::AT_EMPTY_PATH | libc::AT_RECURSIVE) as libc::c_uint, + &mut attr as *mut libc::mount_attr, + size_of::<libc::mount_attr>() as libc::size_t, + );
All of the non-pointer arguments need to be cast to libc::c_long or (equivalently and possibly better) core::ffi::c_long.
I wish this was better documented, but sounds right.
diff --git a/tools/mount-flatpak/src/metadata.rs b/tools/mount-flatpak/src/metadata.rs new file mode 100644 index 0000000..dfc05b1 --- /dev/null +++ b/tools/mount-flatpak/src/metadata.rs @@ -0,0 +1,19 @@ +// SPDX-License-Identifier: EUPL-1.2+ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +use std::fs::File; +use std::io::read_to_string; + +use crate::keyfile::parse; + +pub fn extract_runtime(mut metadata: File) -> Result<String, String> { + let metadata = read_to_string(&mut metadata).map_err(|e| e.to_string())?;
Missing limit on the size of the file to prevent unbounded memory allocation.
There are lots of ways to cause unbounded host memory allocation. Modifying everything to limit size is not feasible. The only way to prevent this is to run this stuff in a VM-scoped cgroup.
On 11/29/25 14:00, Alyssa Ross wrote:
Demi Marie Obenour <demiobenour@gmail.com> writes:
On 11/27/25 15:23, Alyssa Ross wrote:
diff --git a/tools/mount-flatpak/src/main.rs b/tools/mount-flatpak/src/main.rs new file mode 100644 index 0000000..fd2f74f --- /dev/null +++ b/tools/mount-flatpak/src/main.rs @@ -0,0 +1,252 @@ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> +// SPDX-License-Identifier: EUPL-1.2+ + +mod keyfile; +mod metadata; + +use std::borrow::Cow; +use std::env::{ArgsOs, args_os}; +use std::ffi::OsStr; +use std::io; +use std::os::unix::prelude::*; +use std::path::{Path, PathBuf}; +use std::process::exit; + +use pathrs::Root; +use pathrs::flags::{OpenFlags, ResolverFlags}; +use rustix::fs::{CWD, FileType, fstat}; +use rustix::mount::{MoveMountFlags, OpenTreeFlags, move_mount, open_tree}; + +use metadata::extract_runtime; + +fn ex_usage() -> ! { + eprintln!("Usage: mount-flatpak installation app"); + exit(1); +}
Stale usage message.
Will fix.
+fn run(mut args: ArgsOs) -> Result<(), String> { + let Some(user_data_path) = args.next().map(PathBuf::from) else { + ex_usage(); + };
This should be an absolute path, as the working directory isn't one that the user should be caring about.
I don't see any reason to restrict the user like that.
The advantage is better error messages. A relative path will result in a confusing "does not exist" error at best. Definitely should not block committing this.
+ let Some(installation_path) = args.next().map(PathBuf::from) else { + ex_usage(); + }; + let Some(app) = args.next() else { + ex_usage(); + };
I recommend checking that 'app' is not empty, '.' or '..' and does not contain '/'.
I think this is a sign we really need to be using the flatpak installation as a root. We need to be protecting *systematically* against escapes from the flatpak directory to elsewhere on the user data partition, because that's where all the interesting data is.
I 100% agree with this.
This comment[1] gives me the impression that it we should be okay opening a root for the user data partition, resolving the installation path inside the user partition, and creating a new root from that, to be used for everything within it.
(We don't need to go any more granular than that, because it never makes sense for individual subdirectories of the Flatpak repository to be specifically writable by a VM, I think. So we assume that whatever writes the Flatpak repository already has access to the whole repository, and is not interested in tricking the host to do things to it that it could have just directly done itself.)
[1]: https://github.com/cyphar/libpathrs/issues/26#issuecomment-586382681
Fair.
+ let target_installation_dir = open_tree( + CWD, + "flatpak", + OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE,
Missing AT_SYMLINK_NOFOLLOW unless it is is implied.
We rely on nothing malicious being able to mess with the target directory while we're running, and we do not create flatpak as a symlink.
Still good practice anyway, but not a blocker.
+ ) + .map_err(|e| format!("opening target flatpak installation: {e}"))?; + let mut target_installation_dir = Root::from_fd(target_installation_dir); + target_installation_dir.set_resolver_flags(ResolverFlags::NO_SYMLINKS);
Is NO_XDEV implied? It's not supported in the API but it would be useful to check.
It is not implied, but there's no way to set it either.
That is a little bit annoying, but not a blocker.
+ let mut full_app_path = installation_path.join("app"); + full_app_path.push(&app); + full_app_path.push("current"); + let arch_and_branch = source_installation_dir + .readlink(&full_app_path) + .map_err(|e| format!("reading current app arch and branch: {e}"))?;
This is somewhat hard to understand. I recommend a big comment at the start of the file explaining the structure of the source directory, which is:
VM's directory/ Installation root/ app/ App ID/ current -> arch/branch arch/ branch/ active -> actual commit hash (64 bytes lowercase hex) commit hash metadata (contains runtime info) runtime/ Runtime ID/ arch/ branch/ active -> actual commit hash (64 bytes lowercase hex) commit hash
As well as that of the target directory, which I'm not sure about.
I can do that.
(The target directory is just an installation with a single app and single runtime installed.)
Thank you!
+ let mut components = arch_and_branch.components(); + let arch = components.next().unwrap().as_os_str(); + let branch = components.as_path().as_os_str(); + if branch.is_empty() { + return Err("can't infer branch from \"current\" link".to_string()); + } + + full_app_path.pop(); + full_app_path.push(&arch_and_branch); + full_app_path.push("active"); + let commit = source_installation_dir + .readlink(&full_app_path) + .map_err(|e| format!("reading active app commit: {e}"))? + .into_os_string(); + + full_app_path.pop(); + full_app_path.push(&commit); + let source_app_dir = source_installation_dir + .resolve(&full_app_path) + .map_err(|e| format!("opening source app directory: {e}"))?; + + let metadata = source_installation_dir + .resolve(full_app_path.join("metadata")) + .map_err(|e| format!("resolving app metadata: {e}"))?; + + let metadata_stat = + fstat(&metadata).map_err(|e| format!("checking app metadata is a regular file: {e}"))?; + let metadata_type = FileType::from_raw_mode(metadata_stat.st_mode); + if !metadata_type.is_file() { + let e = format!("type of app metadata is {metadata_type:?}, not RegularFile"); + return Err(e); + } + let metadata = metadata + .reopen(OpenFlags::O_RDONLY) + .map_err(|e| format!("opening app metadata: {e}"))?; + + let runtime = + extract_runtime(metadata).map_err(|e| format!("reading runtime from metadata: {e}"))?; + + let mut full_runtime_path = installation_path.join("runtime"); + full_runtime_path.push(runtime); + full_runtime_path.push("active"); + let runtime_commit = source_installation_dir + .readlink(&full_runtime_path) + .map_err(|e| format!("reading active runtime commit: {e}"))? + .into_os_string(); + + full_runtime_path.pop(); + full_runtime_path.push(&runtime_commit); + let source_runtime_dir = source_installation_dir + .resolve(&full_runtime_path) + .map_err(|e| format!("opening source runtime directory: {e}"))?; + + let target_app_dir = target_installation_dir + .mkdir_all(&full_app_path, &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating target app directory: {e}"))?; + let target_runtime_dir = target_installation_dir + .mkdir_all(&full_runtime_path, &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating target runtime directory: {e}"))?; + + let source_app_tree = open_tree( + &source_app_dir, + "", + OpenTreeFlags::AT_EMPTY_PATH + | OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE, + ) + .map_err(|e| format!("cloning source app tree: {e}"))?; + let source_runtime_tree = open_tree( + &source_runtime_dir, + "", + OpenTreeFlags::AT_EMPTY_PATH + | OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE, + ) + .map_err(|e| format!("cloning source runtime tree: {e}"))?; + + move_mount( + source_app_tree, + "", + target_app_dir, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting app directory: {e}"))?; + move_mount( + source_runtime_tree, + "", + target_runtime_dir, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting runtime directory: {e}"))?; + + target_installation_dir + .mkdir_all("repo/objects", &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating repo/objects: {e}"))?; + target_installation_dir + .mkdir_all("repo/tmp/cache", &PermissionsExt::from_mode(0o700)) + .map_err(|e| format!("creating repo/tmp/cache: {e}"))?; + let config_target = target_installation_dir + .create_file( + "repo/config", + OpenFlags::O_WRONLY | OpenFlags::O_CLOEXEC, + &PermissionsExt::from_mode(0o700), + ) + .map_err(|e| format!("creating repo/config: {e}"))?; + let config_source_path = env!("MOUNT_FLATPAK_CONFIG_PATH");
This should always be an absolute path, and it might be good to assert that.
str::contains is not const, so it's not possible to do this in the obvious way, but it's also not critical to validate a compile-time constant we know we're always setting correctly. Would consider a patch.
Ah, I forgot that this is a compile-time constant.
+ let config_source = open_tree( + CWD, + config_source_path, + OpenTreeFlags::OPEN_TREE_CLONE | OpenTreeFlags::OPEN_TREE_CLOEXEC, + ) + .map_err(|e| format!("opening {config_source_path}: {e}"))?; + move_mount( + config_source, + "", + config_target, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting config: {e}"))?; + + let mut attr = libc::mount_attr { + attr_clr: libc::MOUNT_ATTR_NOSYMFOLLOW, + attr_set: libc::MOUNT_ATTR_RDONLY | libc::MOUNT_ATTR_NODEV, + propagation: 0, + userns_fd: 0, + };
Propagation should likely be set to MS_SLAVE. (Yeah, I know, terrible name.) attr_set should also include MOUNT_ATTR_NOEXEC as well as the host has no business executing anything there.
The host has no business executing anything at all from the whole user data partition, so this is not the place to set that. There's no reason this mount _in particular_ needs the flag set that doesn't apply to the whole partition this mount's flags are inherited from.
Good point, but I still think the propagation needs to be set to MS_SLAVE. Right now, mount flags are set manually by the user.
+ let empty = b"\0"; + // SAFETY: we pass a valid FD, and a valid mutable pointer with the correct size. + unsafe { + let r = libc::syscall( + libc::SYS_mount_setattr, + target_installation_dir.as_fd(), + empty.as_ptr() as *const libc::c_char, + (libc::AT_EMPTY_PATH | libc::AT_RECURSIVE) as libc::c_uint, + &mut attr as *mut libc::mount_attr, + size_of::<libc::mount_attr>() as libc::size_t, + );
All of the non-pointer arguments need to be cast to libc::c_long or (equivalently and possibly better) core::ffi::c_long.
I wish this was better documented, but sounds right.
Technically, the pointers should be cast too, but I'm more concerned about rustc assuming this means the data the pointers point to won't be accessed than about something that is guaranteed to work by the ABI.
diff --git a/tools/mount-flatpak/src/metadata.rs b/tools/mount-flatpak/src/metadata.rs new file mode 100644 index 0000000..dfc05b1 --- /dev/null +++ b/tools/mount-flatpak/src/metadata.rs @@ -0,0 +1,19 @@ +// SPDX-License-Identifier: EUPL-1.2+ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +use std::fs::File; +use std::io::read_to_string; + +use crate::keyfile::parse; + +pub fn extract_runtime(mut metadata: File) -> Result<String, String> { + let metadata = read_to_string(&mut metadata).map_err(|e| e.to_string())?;
Missing limit on the size of the file to prevent unbounded memory allocation.
There are lots of ways to cause unbounded host memory allocation. Modifying everything to limit size is not feasible. The only way to prevent this is to run this stuff in a VM-scoped cgroup. It's easy to run the VM's services in a cgroup, but running commands like this in the cgroup is harder. Also, this command is much easier to make robust against problems like that.
Should not block commit though. -- Sincerely, Demi Marie Obenour (she/her/hers)
Demi Marie Obenour <demiobenour@gmail.com> writes:
On 11/29/25 14:00, Alyssa Ross wrote:
Demi Marie Obenour <demiobenour@gmail.com> writes:
On 11/27/25 15:23, Alyssa Ross wrote:
+fn run(mut args: ArgsOs) -> Result<(), String> { + let Some(user_data_path) = args.next().map(PathBuf::from) else { + ex_usage(); + };
This should be an absolute path, as the working directory isn't one that the user should be caring about.
I don't see any reason to restrict the user like that.
The advantage is better error messages. A relative path will result in a confusing "does not exist" error at best.
Definitely should not block committing this.
From what I can tell mount-flatpak works fine with relative paths — are you talking about the cd in run-flatpak? I don't think it makes sense for one program to reject valid inputs that might be invalid to a higher layer that runs it, but we could consider moving the cd into mount-flatpak by adding yet another argument for the destination directory.
+ let target_installation_dir = open_tree( + CWD, + "flatpak", + OpenTreeFlags::OPEN_TREE_CLONE + | OpenTreeFlags::OPEN_TREE_CLOEXEC + | OpenTreeFlags::AT_RECURSIVE,
Missing AT_SYMLINK_NOFOLLOW unless it is is implied.
We rely on nothing malicious being able to mess with the target directory while we're running, and we do not create flatpak as a symlink.
Still good practice anyway, but not a blocker.
Will add.
+ let config_source = open_tree( + CWD, + config_source_path, + OpenTreeFlags::OPEN_TREE_CLONE | OpenTreeFlags::OPEN_TREE_CLOEXEC, + ) + .map_err(|e| format!("opening {config_source_path}: {e}"))?; + move_mount( + config_source, + "", + config_target, + "", + MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH | MoveMountFlags::MOVE_MOUNT_T_EMPTY_PATH, + ) + .map_err(|e| format!("mounting config: {e}"))?; + + let mut attr = libc::mount_attr { + attr_clr: libc::MOUNT_ATTR_NOSYMFOLLOW, + attr_set: libc::MOUNT_ATTR_RDONLY | libc::MOUNT_ATTR_NODEV, + propagation: 0, + userns_fd: 0, + };
Propagation should likely be set to MS_SLAVE. (Yeah, I know, terrible name.) attr_set should also include MOUNT_ATTR_NOEXEC as well as the host has no business executing anything there.
The host has no business executing anything at all from the whole user data partition, so this is not the place to set that. There's no reason this mount _in particular_ needs the flag set that doesn't apply to the whole partition this mount's flags are inherited from.
Good point, but I still think the propagation needs to be set to MS_SLAVE. Right now, mount flags are set manually by the user.
Will do.
diff --git a/tools/mount-flatpak/src/metadata.rs b/tools/mount-flatpak/src/metadata.rs new file mode 100644 index 0000000..dfc05b1 --- /dev/null +++ b/tools/mount-flatpak/src/metadata.rs @@ -0,0 +1,19 @@ +// SPDX-License-Identifier: EUPL-1.2+ +// SPDX-FileCopyrightText: 2025 Alyssa Ross <hi@alyssa.is> + +use std::fs::File; +use std::io::read_to_string; + +use crate::keyfile::parse; + +pub fn extract_runtime(mut metadata: File) -> Result<String, String> { + let metadata = read_to_string(&mut metadata).map_err(|e| e.to_string())?;
Missing limit on the size of the file to prevent unbounded memory allocation.
There are lots of ways to cause unbounded host memory allocation. Modifying everything to limit size is not feasible. The only way to prevent this is to run this stuff in a VM-scoped cgroup. It's easy to run the VM's services in a cgroup, but running commands like this in the cgroup is harder. Also, this command is much easier to make robust against problems like that.
Should not block commit though.
I don't see why it needs to be. The cgroup will have to be created by run-flatpak, so why wouldn't it be able to run mount-flatpak in that cgroup?
participants (2)
-
Alyssa Ross -
Demi Marie Obenour