Re: [PATCH] Docs: web server must setenv GIT_PROTOCOL for v2
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Sep 9, 2021, 17:28 UTC
- Message-ID
- <xmqqee9x1wvh.fsf@gitster.g>
- In-Reply-To
- <YTiXEEEs36NCEr9S@coredump.intra.peff.net>
Jeff King <peff@peff.net> writes:
Show 8 quoted lines
> On Wed, Sep 08, 2021 at 06:48:47AM -0400, Jeff King wrote: > >> Both of the included examples here have been tested to work. The one for >> lighttpd is a little less direct than I'd like, but I couldn't find a >> way to directly set an environment variable to the value of a request >> header. From my reading of the documentation, lighttpd will set >> HTTP_GIT_PROTOCOL automatically, but git-http-backend looks only at >> GIT_PROTOCOL. Arguably http-backend should do this translation itself.
Nice.
These headers get HTTP_* prefixed as a security measure when servers expose them to their configuration mechanisms because these names are attacker controlled. I had a flawed mental model in which the servers' configuration controls which one of these resulting HTTP_* headers are passed to CGI and externals selectively, but if servers pass all HTTP_* environment variables to CGI and externals without any filtering, the patch you gave here is the most logical solution.
Will queue.
Show 55 quoted lines
> -- >8 --
> Subject: [PATCH] http-backend: handle HTTP_GIT_PROTOCOL CGI variable
>
> When a client requests the v2 protocol over HTTP, they set the
> Git-Protocol header. Webservers will generaly make that available to our
> CGI as HTTP_GIT_PROTOCOL in the environment. However, that's not
> sufficient for upload-pack, etc, to respect it; they look in
> GIT_PROTOCOL (without the HTTP_ prefix).
>
> Either the webserver or the CGI is responsible for relaying that HTTP
> header into the GIT_PROTOCOL variable. Traditionally, our tests have
> configured the webserver to do so, but that's a burden on the server
> admin. We can make this work out of the box by having the http-backend
> CGI copy the contents.
>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
> http-backend.c | 4 ++++
> t/lib-httpd/apache.conf | 2 --
> 2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/http-backend.c b/http-backend.c
> index b329bf63f0..2f4b4c11de 100644
> --- a/http-backend.c
> +++ b/http-backend.c
> @@ -739,6 +739,7 @@ static int bad_request(struct strbuf *hdr, const struct service_cmd *c)
> int cmd_main(int argc, const char **argv)
> {
> char *method = getenv("REQUEST_METHOD");
> + const char *proto_header;
> char *dir;
> struct service_cmd *cmd = NULL;
> char *cmd_arg = NULL;
> @@ -789,6 +790,9 @@ int cmd_main(int argc, const char **argv)
> http_config();
> max_request_buffer = git_env_ulong("GIT_HTTP_MAX_REQUEST_BUFFER",
> max_request_buffer);
> + proto_header = getenv("HTTP_GIT_PROTOCOL");
> + if (proto_header)
> + setenv(GIT_PROTOCOL_ENVIRONMENT, proto_header, 1);
>
> cmd->imp(&hdr, cmd_arg);
> return 0;
> diff --git a/t/lib-httpd/apache.conf b/t/lib-httpd/apache.conf
> index afa91e38b0..71761e3299 100644
> --- a/t/lib-httpd/apache.conf
> +++ b/t/lib-httpd/apache.conf
> @@ -81,8 +81,6 @@ PassEnv GIT_TRACE
> PassEnv GIT_CONFIG_NOSYSTEM
> PassEnv GIT_TEST_SIDEBAND_ALL
>
> -SetEnvIf Git-Protocol ".*" GIT_PROTOCOL=$0
> -
> Alias /dumb/ www/
> Alias /auth/dumb/ www/auth/dumb/