Merge branch 'jk/http-walker-limit-redirect-2.9'

Transport with dumb http can be fooled into following foreign URLs
that the end user does not intend to, especially with the server
side redirects and http-alternates mechanism, which can lead to
security issues.  Tighten the redirection and make it more obvious
to the end user when it happens.

* jk/http-walker-limit-redirect-2.9:
  http: treat http-alternates like redirects
  http: make redirects more obvious
  remote-curl: rename shadowed options variable
  http: always update the base URL for redirects
  http: simplify update_url_from_redirect

1 files changed, 61 insertions, 0 deletions

diff --git a/t/t5550-http-fetch-dumb.sh b/t/t5550-http-fetch-dumb.sh
index 7641417b4a..264a1ab8b0 100755
--- a/t/t5550-http-fetch-dumb.sh
+++ b/t/t5550-http-fetch-dumb.sh
@@ -307,5 +307,66 @@ test_expect_success 'remote-http complains cleanly about malformed urls' '
 	test_must_fail git remote-http http::/example.com/repo.git
 '
 
+test_expect_success 'redirects can be forbidden/allowed' '
+	test_must_fail git -c http.followRedirects=false \
+		clone $HTTPD_URL/dumb-redir/repo.git dumb-redir &&
+	git -c http.followRedirects=true \
+		clone $HTTPD_URL/dumb-redir/repo.git dumb-redir 2>stderr
+'
+
+test_expect_success 'redirects are reported to stderr' '
+	# just look for a snippet of the redirected-to URL
+	test_i18ngrep /dumb/ stderr
+'
+
+test_expect_success 'non-initial redirects can be forbidden' '
+	test_must_fail git -c http.followRedirects=initial \
+		clone $HTTPD_URL/redir-objects/repo.git redir-objects &&
+	git -c http.followRedirects=true \
+		clone $HTTPD_URL/redir-objects/repo.git redir-objects
+'
+
+test_expect_success 'http.followRedirects defaults to "initial"' '
+	test_must_fail git clone $HTTPD_URL/redir-objects/repo.git default
+'
+
+# The goal is for a clone of the "evil" repository, which has no objects
+# itself, to cause the client to fetch objects from the "victim" repository.
+test_expect_success 'set up evil alternates scheme' '
+	victim=$HTTPD_DOCUMENT_ROOT_PATH/victim.git &&
+	git init --bare "$victim" &&
+	git -C "$victim" --work-tree=. commit --allow-empty -m secret &&
+	git -C "$victim" repack -ad &&
+	git -C "$victim" update-server-info &&
+	sha1=$(git -C "$victim" rev-parse HEAD) &&
+
+	evil=$HTTPD_DOCUMENT_ROOT_PATH/evil.git &&
+	git init --bare "$evil" &&
+	# do this by hand to avoid object existence check
+	printf "%s\\t%s\\n" $sha1 refs/heads/master >"$evil/info/refs"
+'
+
+# Here we'll just redirect via HTTP. In a real-world attack these would be on
+# different servers, but we should reject it either way.
+test_expect_success 'http-alternates is a non-initial redirect' '
+	echo "$HTTPD_URL/dumb/victim.git/objects" \
+		>"$evil/objects/info/http-alternates" &&
+	test_must_fail git -c http.followRedirects=initial \
+		clone $HTTPD_URL/dumb/evil.git evil-initial &&
+	git -c http.followRedirects=true \
+		clone $HTTPD_URL/dumb/evil.git evil-initial
+'
+
+# Curl supports a lot of protocols that we'd prefer not to allow
+# http-alternates to use, but it's hard to test whether curl has
+# accessed, say, the SMTP protocol, because we are not running an SMTP server.
+# But we can check that it does not allow access to file://, which would
+# otherwise allow this clone to complete.
+test_expect_success 'http-alternates cannot point at funny protocols' '
+	echo "file://$victim/objects" >"$evil/objects/info/http-alternates" &&
+	test_must_fail git -c http.followRedirects=true \
+		clone "$HTTPD_URL/dumb/evil.git" evil-file
+'
+
 stop_httpd
 test_done