git/t/lib-httpd/apache.conf, branch v2.13.2

http: attempt updating base URL only if no error

2017-02-28T19:35:53Z

http.c supports HTTP redirects of the form http://foo/info/refs?service=git-upload-pack -> http://anything -> http://bar/info/refs?service=git-upload-pack (that is to say, as long as the Git part of the path and the query string is preserved in the final redirect destination, the intermediate steps can have any URL). However, if one of the intermediate steps results in an HTTP exception, a confusing "unable to update url base from redirection" message is printed instead of a Curl error message with the HTTP exception code. This was introduced by 2 commits. Commit c93c92f ("http: update base URLs when we see redirects", 2013-09-28) introduced a best-effort optimization that required checking if only the "base" part of the URL differed between the initial request and the final redirect destination, but it performed the check before any HTTP status checking was done. If something went wrong, the normal code path was still followed, so this did not cause any confusing error messages until commit 6628eb4 ("http: always update the base URL for redirects", 2016-12-06), which taught http to die if the non-"base" part of the URL differed. Therefore, teach http to check the HTTP status before attempting to check if only the "base" part of the URL differed. This commit teaches http_request_reauth to return early without updating options->base_url upon an error; the only invoker of this function that passes a non-NULL "options" is remote-curl.c (through "http_get_strbuf"), which only uses options->base_url for an informational message in the situations that this commit cares about (that is, when the return value is not HTTP_OK). The included test checks that the redirect scheme at the beginning of this commit message works, and that returning a 502 in the middle of the redirect scheme produces the correct result. Note that this is different from the test in commit 6628eb4 ("http: always update the base URL for redirects", 2016-12-06) in that this commit tests that a Git-shaped URL (http://.../info/refs?service=git-upload-pack) works, whereas commit 6628eb4 tests that a non-Git-shaped URL (http://.../info/refs/foo?service=git-upload-pack) does not work (even though Git is processing that URL) and is an error that is fatal, not silently swallowed. Signed-off-by: Jonathan Tan Acked-by: Jeff King Signed-off-by: Junio C Hamano

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

2016-12-19T22:45:32Z

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

http: make redirects more obvious

2016-12-06T20:32:48Z

We instruct curl to always follow HTTP redirects. This is convenient, but it creates opportunities for malicious servers to create confusing situations. For instance, imagine Alice is a git user with access to a private repository on Bob's server. Mallory runs her own server and wants to access objects from Bob's repository. Mallory may try a few tricks that involve asking Alice to clone from her, build on top, and then push the result: 1. Mallory may simply redirect all fetch requests to Bob's server. Git will transparently follow those redirects and fetch Bob's history, which Alice may believe she got from Mallory. The subsequent push seems like it is just feeding Mallory back her own objects, but is actually leaking Bob's objects. There is nothing in git's output to indicate that Bob's repository was involved at all. The downside (for Mallory) of this attack is that Alice will have received Bob's entire repository, and is likely to notice that when building on top of it. 2. If Mallory happens to know the sha1 of some object X in Bob's repository, she can instead build her own history that references that object. She then runs a dumb http server, and Alice's client will fetch each object individually. When it asks for X, Mallory redirects her to Bob's server. The end result is that Alice obtains objects from Bob, but they may be buried deep in history. Alice is less likely to notice. Both of these attacks are fairly hard to pull off. There's a social component in getting Mallory to convince Alice to work with her. Alice may be prompted for credentials in accessing Bob's repository (but not always, if she is using a credential helper that caches). Attack (1) requires a certain amount of obliviousness on Alice's part while making a new commit. Attack (2) requires that Mallory knows a sha1 in Bob's repository, that Bob's server supports dumb http, and that the object in question is loose on Bob's server. But we can probably make things a bit more obvious without any loss of functionality. This patch does two things to that end. First, when we encounter a whole-repo redirect during the initial ref discovery, we now inform the user on stderr, making attack (1) much more obvious. Second, the decision to follow redirects is now configurable. The truly paranoid can set the new http.followRedirects to false to avoid any redirection entirely. But for a more practical default, we will disallow redirects only after the initial ref discovery. This is enough to thwart attacks similar to (2), while still allowing the common use of redirects at the repository level. Since c93c92f30 (http: update base URLs when we see redirects, 2013-09-28) we re-root all further requests from the redirect destination, which should generally mean that no further redirection is necessary. As an escape hatch, in case there really is a server that needs to redirect individual requests, the user can set http.followRedirects to "true" (and this can be done on a per-server basis via http.*.followRedirects config). Reported-by: Jann Horn Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

http: always update the base URL for redirects

2016-12-06T20:32:48Z

If a malicious server redirects the initial ref advertisement, it may be able to leak sha1s from other, unrelated servers that the client has access to. For example, imagine that Alice is a git user, she has access to a private repository on a server hosted by Bob, and Mallory runs a malicious server and wants to find out about Bob's private repository. Mallory asks Alice to clone an unrelated repository from her over HTTP. When Alice's client contacts Mallory's server for the initial ref advertisement, the server issues an HTTP redirect for Bob's server. Alice contacts Bob's server and gets the ref advertisement for the private repository. If there is anything to fetch, she then follows up by asking the server for one or more sha1 objects. But who is the server? If it is still Mallory's server, then Alice will leak the existence of those sha1s to her. Since commit c93c92f30 (http: update base URLs when we see redirects, 2013-09-28), the client usually rewrites the base URL such that all further requests will go to Bob's server. But this is done by textually matching the URL. If we were originally looking for "http://mallory/repo.git/info/refs", and we got pointed at "http://bob/other.git/info/refs", then we know that the right root is "http://bob/other.git". If the redirect appears to change more than just the root, we punt and continue to use the original server. E.g., imagine the redirect adds a URL component that Bob's server will ignore, like "http://bob/other.git/info/refs?dummy=1". We can solve this by aborting in this case rather than silently continuing to use Mallory's server. In addition to protecting from sha1 leakage, it's arguably safer and more sane to refuse a confusing redirect like that in general. For example, part of the motivation in c93c92f30 is avoiding accidentally sending credentials over clear http, just to get a response that says "try again over https". So even in a non-malicious case, we'd prefer to err on the side of caution. The downside is that it's possible this will break a legitimate but complicated server-side redirection scheme. The setup given in the newly added test does work, but it's convoluted enough that we don't need to care about it. A more plausible case would be a server which redirects a request for "info/refs?service=git-upload-pack" to just "info/refs" (because it does not do smart HTTP, and for some reason really dislikes query parameters). Right now we would transparently downgrade to dumb-http, but with this patch, we'd complain (and the user would have to set GIT_SMART_HTTP=0 to fetch). Reported-by: Jann Horn Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

Merge branch 'ew/git-svn-http-tests'

2016-08-08T21:48:34Z

Tests for "git svn" have been taught to reuse the lib-httpd test infrastructure when testing the subversion integration that interacts with subversion repositories served over the http:// protocol. * ew/git-svn-http-tests: git svn: migrate tests to use lib-httpd t/t91*: do not say how to avoid the tests

git svn: migrate tests to use lib-httpd

2016-07-25T17:42:34Z

This allows us to use common test infrastructure and parallelize the tests. For now, GIT_SVN_TEST_HTTPD=true needs to be set to enable the SVN HTTP tests because we reuse the same test cases for both file:// and http:// SVN repositories. SVN_HTTPD_PORT is no longer honored. Tested under Apache 2.2 and 2.4 on Debian 7.x (wheezy) and 8.x (jessie), respectively. Cc: Clemens Buchacher Cc: Michael J Gruber Signed-off-by: Eric Wong Signed-off-by: Junio C Hamano

Merge branch 'js/http-custom-headers'

2016-05-17T21:38:35Z

Update tests for "http.extraHeaders=

" to be portable back to Apache 2.2 (the original depended on which is a more recent feature). * js/http-custom-headers: submodule: ensure that -c http.extraheader is heeded t5551: make the test for extra HTTP headers more robust tests: adjust the configuration for Apache 2.2

tests: adjust the configuration for Apache 2.2

2016-05-10T17:27:42Z

Lars Schneider noticed that the configuration introduced to test the extra HTTP headers cannot be used with Apache 2.2 (which is still actively maintained, as pointed out by Junio Hamano). To let the tests pass with Apache 2.2 again, let's substitute the offending and `expr` by using old school RewriteCond statements. As RewriteCond does not allow testing for *non*-matches, we simply match the desired case first and let it pass by marking the RewriteRule as '[L]' ("last rule, do not process any other matching RewriteRules after this"), and then have another RewriteRule that matches all other cases and lets them fail via '[F]' ("fail"). Signed-off-by: Johannes Schindelin Tested-by: Lars Schneider Signed-off-by: Junio C Hamano

Merge branch 'js/http-custom-headers'

2016-05-06T21:45:43Z

HTTP transport clients learned to throw extra HTTP headers at the server, specified via http.extraHeader configuration variable. * js/http-custom-headers: http: support sending custom HTTP headers

http: support sending custom HTTP headers

2016-04-27T21:02:33Z

We introduce a way to send custom HTTP headers with all requests. This allows us, for example, to send an extra token from build agents for temporary access to private repositories. (This is the use case that triggered this patch.) This feature can be used like this: git -c http.extraheader='Secret: sssh!' fetch $URL $REF Note that `curl_easy_setopt(..., CURLOPT_HTTPHEADER, ...)` takes only a single list, overriding any previous call. This means we have to collect _all_ of the headers we want to use into a single list, and feed it to cURL in one shot. Since we already unconditionally set a "pragma" header when initializing the curl handles, we can add our new headers to that list. For callers which override the default header list (like probe_rpc), we provide `http_copy_default_headers()` so they can do the same trick. Big thanks to Jeff King and Junio Hamano for their outstanding help and patient reviews. Signed-off-by: Johannes Schindelin Reviewed-by: Jeff King Signed-off-by: Junio C Hamano