Re: [PATCH/RFC] push: anonymize URL in error output

[Lars Schneider <larsxschneider@gmail.com>]

> On 23 Aug 2017, at 11:49, Ivan Vyshnevskyi <sainaen@gmail.com> wrote:
> 
> Commits 47abd85 (fetch: Strip usernames from url's before storing them,
> 2009-04-17) and later 882d49c (push: anonymize URL in status output,
> 2016-07-14) made fetch and push strip the authentication part of the
> remote URLs when used in the merge-commit messages or status outputs.
> The URLs that are part of the error messages were not anonymized.
> 
> A commonly used pattern for storing artifacts from a build server in a
> remote repository utilizes a "secure" environment variable with
> credentials to embed them in the URL and execute a push. Given enough
> runs, an intermittent network failure will cause a push to fail, leaving
> a non-anonymized URL in the build log.
> 
> To prevent that, reuse the same anonymizing function to scrub
> credentials from URL in the push error output.
> 
> Signed-off-by: Ivan Vyshnevskyi <sainaen@gmail.com>
> ---
> 
> This is my first attempt to propose a patch, sorry if I did something wrong!
> 
> I've tested my changes on Travis CI, and the build is green [1].
> 
> Not sure how much of the background should be included in the commit message.
> The "commonly used pattern" I mention could be found in the myriad of
> online tutorials and looks something like this:
> 
>    git push -fq https://$GIT_CREDS@github.com/$REPO_SLUG
> 
> Note, that a lot of developers mistakenly assume that '--quiet' ('-q') will
> suppress all output. Sometimes, they would redirect standard output to
> /dev/null, without realizing that errors are printed out to stderr.
> 
> I didn't mention this in the commit, but another typical offender is a tool that
> calls 'git push' as part of its execution. This is a spectrum that starts with
> shell scripts, includes simple one-task apps in Python or Ruby, and ends with
> the plugins for JavaScript, Java, Groovy, and Scala build tools. (I'd like to
> avoid shaming their authors publicly, but could send you a few examples
> privately.)
> 
> I gathered the data by going through build logs of popular open source projects
> (and projects of their contributors) hosted on GitHub and built by Travis CI.
> I found about 2.3k unique credentials (but only about nine hundred were active
> at the time), and more than a half of those were exposed by a failed push. See
> the advisory from Travis CI [2] for results of their own scan.
> 
> While the issue is public for several months now and addressed on Travis CI,
> I keep finding build logs with credentials on the internet. So I think it's
> worth fixing in the git itself.
> 
> [1]: https://travis-ci.org/sainaen/git/builds/267180560
> [2]: https://blog.travis-ci.com/2017-05-08-security-advisory
> 

This sounds very reasonable to me! Thanks for the contribution!

I wonder if we should even extend this. Consider this case:

  $ git push https://lars:secret@server/org/repo1
  remote: Invalid username or password.
  fatal: Authentication failed for 'https://lars:secret@server/org/repo1/'

I might not have valid credentials for repo1 but my credentials could
very well be valid for repo2.

- Lars


> builtin/push.c             |  2 +-
> t/t5541-http-push-smart.sh | 18 ++++++++++++++++++
> 2 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/builtin/push.c b/builtin/push.c
> index 03846e837..59f3bc975 100644
> --- a/builtin/push.c
> +++ b/builtin/push.c
> @@ -336,7 +336,7 @@ static int push_with_options(struct transport *transport, int flags)
> 	err = transport_push(transport, refspec_nr, refspec, flags,
> 			     &reject_reasons);
> 	if (err != 0)
> -		error(_("failed to push some refs to '%s'"), transport->url);
> +		error(_("failed to push some refs to '%s'"), transport_anonymize_url(transport->url));
> 
> 	err |= transport_disconnect(transport);
> 	if (!err)
> diff --git a/t/t5541-http-push-smart.sh b/t/t5541-http-push-smart.sh
> index d38bf3247..0b6fb6252 100755
> --- a/t/t5541-http-push-smart.sh
> +++ b/t/t5541-http-push-smart.sh
> @@ -377,5 +377,23 @@ test_expect_success 'push status output scrubs password' '
> 	grep "^To $HTTPD_URL/smart/test_repo.git" status
> '
> 
> +cat >"$HTTPD_DOCUMENT_ROOT_PATH/test_repo.git/hooks/update" <<EOF
> +#!/bin/sh
> +exit 1
> +EOF
> +chmod a+x "$HTTPD_DOCUMENT_ROOT_PATH/test_repo.git/hooks/update"
> +
> +cat >exp <<EOF
> +error: failed to push some refs to '$HTTPD_URL/smart/test_repo.git'
> +EOF
> +
> +test_expect_success 'failed push status output scrubs password' '
> +	cd "$ROOT_PATH"/test_repo_clone &&
> +	test_must_fail git push "$HTTPD_URL_USER_PASS/smart/test_repo.git" +HEAD:scrub_err 2>stderr &&
> +	grep "^error: failed to push some refs" stderr >act &&
> +	test_i18ncmp exp act
> +'
> +rm -f "$HTTPD_DOCUMENT_ROOT_PATH/test_repo.git/hooks/update"
> +
> stop_httpd
> test_done
> -- 
> 2.14.1
>