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

diff --cc Documentation/config.txt
Simple merge

diff --cc http-walker.c
Simple merge

diff --cc http.c
Simple merge

diff --cc http.h
Simple merge

diff --cc remote-curl.c
Simple merge

diff --cc t/lib-httpd/apache.conf
Simple merge

diff --cc t/t5550-http-fetch-dumb.sh
index 7641417,22011f0..264a1ab
--- 1/t/t5550-http-fetch-dumb.sh
--- 2/t/t5550-http-fetch-dumb.sh
+++ b/t/t5550-http-fetch-dumb.sh
@@@ -295,17 -295,70 +295,78 @@@ ja;q=0.95, zh;q=0.94, sv;q=0.93, pt;q=0
  '
  
  test_expect_success 'git client does not send an empty Accept-Language' '
 -      GIT_CURL_VERBOSE=1 LANGUAGE= git ls-remote "$HTTPD_URL/dumb/repo.git" 2>stderr &&
 -      ! grep "^Accept-Language:" stderr
 +      GIT_TRACE_CURL=true LANGUAGE= git ls-remote "$HTTPD_URL/dumb/repo.git" 2>stderr &&
 +      ! grep "^=> Send header: Accept-Language:" stderr
 +'
 +
 +test_expect_success 'remote-http complains cleanly about malformed urls' '
 +      # do not actually issue "list" or other commands, as we do not
 +      # want to rely on what curl would actually do with such a broken
 +      # URL. This is just about making sure we do not segfault during
 +      # initialization.
 +      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

diff --cc t/t5551-http-fetch-smart.sh
Simple merge