Wrong values for the version or update URL will cause very confusing build-time or runtime errors. Provide a better user experience by validating them up-front. The update URL validator is loose. It rejects only URLs that cannot possibly work: either appending /SHA256SUMS to them doesn't append to the path, or they will definitely be rejected by curl due to being malformed. The version validator is in lib/config.nix, as the version number is used in many places. It checks that the version only uses characters that are permitted by systemd's version number specification [1] and that will not break code that uses them in shell or sed commands. [1]: https://uapi-group.org/specifications/specs/version_format_specification Signed-off-by: Demi Marie Obenour <demiobenour@gmail.com> --- Changes since v4: - Drop compression level. - Centralize validation. - Use camelCase for Nix identifiers. - Clean up formatting. Changes since v3: - Validate compression level. Changes since v2: - Use loose URL validation: allow anything that might work. - Only reject versions that violate the specification. --- lib/config.nix | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-) diff --git a/lib/config.nix b/lib/config.nix index e437cdbe9aa22dd0f9c8d7052ac331c8fccf6ce6..e641642de07c1549e69fc12e91c4e80e2f82d035 100644 --- a/lib/config.nix +++ b/lib/config.nix @@ -17,6 +17,31 @@ let callConfig = config: if builtins.typeOf config == "lambda" then config { inherit default; } else config; + finalConfig = default // callConfig config; + # Use builtins.fromJSON because it supports \uXXXX escapes. + # This is the same regex used by check-url.awk in the update VM. + # The update code is careful to escape any metacharacters, but some + # simply cannot be made to work. Concatenating the URL with /SHA256SUMS + # must append to the path portion of the URL, and the URL must be one + # that libcurl will accept. + urlRegex = builtins.fromJSON "\"^[^\\u0001- #?\\u007F]+$\""; in -default // callConfig config +# Version is used in many files, so validate it here. +# See https://uapi-group.org/specifications/specs/version_format_specification +# for allowed version strings. +if builtins.match "[[:alnum:]_.~^-]+" finalConfig.version == null then + builtins.abort '' + Version ${builtins.toJSON finalConfig.version} has forbidden characters. + Only ASCII alphanumerics, ".", "_", "~", "^", "+", and "-" are allowed. + See <https://uapi-group.org/specifications/specs/version_format_specification>. + '' +else +if builtins.match urlRegex finalConfig.updateUrl == null then + builtins.abort '' + Update URL ${builtins.toJSON finalConfig.updateUrl} has forbidden characters. + Query strings, and fragment specifiers are not supported. + ASCII control characters and whitespace must be %-encoded. + '' +else +finalConfig -- 2.52.0