[pacman-dev] [PATCH] Enable sha256/md5 hash verification if detached signatures are used

Pacman has multiple ways to verify package content integrity: - gpg signature - sha256 - md5 These verification mechanisms overlap each other. gpg signatures already contain hash value of the package content. So if a package signature is present then pacman ignored the other 2 hash values. This worked well with signtures embedded into pacman database. Recently pacman got an ability to handle detached signatures (*.sig files located next to the package files). If pacman verifies detached signature only then one can replace pkg+sig files with some other content and pacman still processes it as a valid package. It open doors for security attacks e.g. 'rollback attack'. To prevent it we need to verify database<->package integrity using hash values stored in the database. This commit fixes FS#67232 The new debug output is: checking package integrity... debug: found cached pkg: /var/cache/pacman/pkg/ruby-2.7.1-2-x86_64.pkg.tar.zst debug: sha256sum: 77baf61c62c5570b3a37cf0c3b16c5d9a97dde6fedd1a3528bf0cc5f96dd5e52 debug: checking sha256sum for /var/cache/pacman/pkg/ruby-2.7.1-2-x86_64.pkg.tar.zst debug: sig data: debug: checking signature for /var/cache/pacman/pkg/ruby-2.7.1-2-x86_64.pkg.tar.zst debug: 1 signatures returned debug: fingerprint: B5971F2C5C10A9A08C60030F786C63F330D7CB92 Signed-off-by: Anatol Pomozov --- lib/libalpm/be_package.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/lib/libalpm/be_package.c b/lib/libalpm/be_package.c index f98832f4..4dde7167 100644 --- a/lib/libalpm/be_package.c +++ b/lib/libalpm/be_package.c @@ -311,7 +311,7 @@ int _alpm_pkg_validate_internal(alpm_handle_t *handle, } } - if(syncpkg && !has_sig) { + if(syncpkg && (!has_sig || !syncpkg->base64_sig)) { if(syncpkg->md5sum && !syncpkg->sha256sum) { _alpm_log(handle, ALPM_LOG_DEBUG, "md5sum: %s\n", syncpkg->md5sum); _alpm_log(handle, ALPM_LOG_DEBUG, "checking md5sum for %s\n", pkgfile); -- 2.28.0