commit e04f03f9626e993bb66d7784d258f95ca07bc769 Author: Nicolas Vigier boklm@torproject.org Date: Thu May 16 12:38:08 2019 +0200

Bug 30480: Check that a signed tag object contains the expected tag name

When checking the signature on a tag, we also need to check that the tag is really the expected tag in order to avoid rollback attacks.

Thanks to Santiago Torres-Arias and Keving Gallagher from NYU for reporting and helping to fix this issue. --- lib/RBM.pm | 11 +++++++++++ 1 file changed, 11 insertions(+)

diff --git a/lib/RBM.pm b/lib/RBM.pm index 4416a0c..75912af 100644 --- a/lib/RBM.pm +++ b/lib/RBM.pm @@ -308,6 +308,16 @@ sub git_commit_sign_id { return gpg_get_fingerprint(@l); }

+sub git_get_signed_tagname { + foreach my $l (split(/\n/, $_[0])) { + # the tag message is separated from headers by an empty line, so we + # ignore anything after the first empty line + return '' unless $l; + return $1 if $l =~ m/^tag (.*)$/; + } + return ''; +} + sub git_tag_sign_id { my ($project, $tag) = @_; my $w = set_git_gpg_wrapper($project); @@ -315,6 +325,7 @@ sub git_tag_sign_id { = capture_exec('git', 'tag', '-v', $tag); unset_git_gpg_wrapper($w); return undef unless $success; + return undef unless git_get_signed_tagname($stdout) eq $tag; return gpg_get_fingerprint(split /\n/, $stderr); }