[PATCH v2 18/18] remote-mediawiki: use "sh" to eliminate unquoted commands
- From
Ævar Arnfjörð Bjarmason <avarab@gmail.com>
- Date
- Sep 21, 2020, 10:40 UTC
- Message-ID
- <20200921104000.2304-19-avarab@gmail.com>
- In-Reply-To
- <20200916102918.29805-1-avarab@gmail.com>
Remove the use of run_git_unquoted() completely with a use of "sh -c" suggested by Jeff King, i.e.:
sh -c '"$@" 2>/dev/null' -- echo sneaky 'argument;id'
I don't think this is needed now for any potential RCE issue. The $remotename argument is ultimately picked by the local user (and similarly, the $local variable comes from a user-supplied refspec).
But completely eliminating the use of unquoted shell arguments has a value in and of itself, by making the code easier to review. As noted in an earlier commit I think the use of IPC::Open3 would be too verbose here, but this "sh -c" trick strikes the right balance between readability and semantic sanity.
Suggested-by: Jeff King <peff@peff.net> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> --- contrib/mw-to-git/git-remote-mediawiki.perl | 24 +++++++-------------- 1 file changed, 8 insertions(+), 16 deletions(-)
diff --git a/contrib/mw-to-git/git-remote-mediawiki.perl b/contrib/mw-to-git/git-remote-mediawiki.perl index d21c18df7b..a5624413dc 100755 --- a/contrib/mw-to-git/git-remote-mediawiki.perl +++ b/contrib/mw-to-git/git-remote-mediawiki.perl @@ -371,8 +371,8 @@ sub get_mw_pages { # usage: $out = run_git_quoted(["command", "args", ...]); # $out = run_git_quoted(["command", "args", ...], "raw"); # don't interpret output as UTF-8. -# $out = run_git_unquoted(["command args"); # don't quote arguments -# $out = run_git_unquoted(["command args", "raw"); # ditto but raw instead of UTF-8 as above +# $out = run_git_quoted_nostderr(["command", "args", ...]); # discard stderr +# $out = run_git_quoted_nostderr(["command", "args", ...], "raw"); # ditto but raw instead of UTF-8 as above sub _run_git { my $args = shift; my $encoding = (shift || 'encoding(UTF-8)'); @@ -391,8 +391,8 @@ sub run_git_quoted { _run_git(["git", @{$_[0]}], $_[1]); } -sub run_git_unquoted { - _run_git(["git $_[0]"], $_[1]); +sub run_git_quoted_nostderr { + _run_git(['sh', '-c', 'git "$@" 2>/dev/null', '--', @{$_[0]}], $_[1]); } sub get_all_mediafiles { @@ -521,10 +521,8 @@ sub download_mw_mediafile { sub get_last_local_revision { # Get note regarding last mediawiki revision. - # - # It's OK to use run_git_unquoted() here because $remotename is - # supplied by the local git itself. - my $note = run_git_unquoted("notes --ref=${remotename}/mediawiki show refs/mediawiki/${remotename}/master 2>/dev/null"); + my $note = run_git_quoted_nostderr(["notes", "--ref=${remotename}/mediawiki", + "show", "refs/mediawiki/${remotename}/master"]); my @note_info = split(/ /, $note); my $lastrevision_number; @@ -1189,16 +1187,10 @@ sub mw_push_revision { my $mw_revision = $last_remote_revid; # Get sha1 of commit pointed by local HEAD - # - # It's OK to use run_git_unquoted() because $local is supplied - # by the local git itself. - my $HEAD_sha1 = run_git_unquoted("rev-parse ${local} 2>/dev/null"); + my $HEAD_sha1 = run_git_quoted_nostderr(["rev-parse", $local]); chomp($HEAD_sha1); # Get sha1 of commit pointed by remotes/$remotename/master - # - # It's OK to use run_git_unquoted() here because $remotename is - # supplied by the local git itself. - my $remoteorigin_sha1 = run_git_unquoted("rev-parse refs/remotes/${remotename}/master 2>/dev/null"); + my $remoteorigin_sha1 = run_git_quoted_nostderr(["rev-parse", "refs/remotes/${remotename}/master"]); chomp($remoteorigin_sha1); if ($last_local_revid > 0 &&
-- 2.28.0.297.g1956fa8f8d