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