From 7737ed5e987dca764d15787d9a7e614989c54ceb Mon Sep 17 00:00:00 2001 From: Petr Stodulka Date: Fri, 23 Oct 2015 17:36:57 +0200 Subject: [PATCH 4/5] http-limit-redirection-to-protocol-whitelist Previously, libcurl would follow redirection to any protocol it was compiled for support with. This is desirable to allow redirection from HTTP to HTTPS. However, it would even successfully allow redirection from HTTP to SFTP, a protocol that git does not otherwise support at all. Furthermore git's new protocol-whitelisting could be bypassed by following a redirect within the remote helper, as it was only enforced at transport selection time. This patch limits redirects within libcurl to HTTP, HTTPS, FTP and FTPS. If there is a protocol-whitelist present, this list is limited to those also allowed by the whitelist. As redirection happens from within libcurl, it is impossible for an HTTP redirect to a protocol implemented within another remote helper. When the curl version git was compiled with is too old to support restrictions on protocol redirection, we warn the user if GIT_ALLOW_PROTOCOL restrictions were requested. This is a little inaccurate, as even without that variable in the environment, we would still restrict SFTP, etc, and we do not warn in that case. But anything else means we would literally warn every time git accesses an http remote. --- http.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/http.c b/http.c index 70eaa26..7b72f7c 100644 --- a/http.c +++ b/http.c @@ -7,6 +7,7 @@ #include "credential.h" #include "version.h" #include "pkt-line.h" +#include "transport.h" int active_requests; int http_is_verbose; @@ -299,6 +300,7 @@ static void set_curl_keepalive(CURL *c) static CURL *get_curl_handle(void) { CURL *result = curl_easy_init(); + long allowed_protocols = 0; if (!curl_ssl_verify) { curl_easy_setopt(result, CURLOPT_SSL_VERIFYPEER, 0); @@ -348,6 +350,21 @@ static CURL *get_curl_handle(void) #elif LIBCURL_VERSION_NUM >= 0x071101 curl_easy_setopt(result, CURLOPT_POST301, 1); #endif +#if LIBCURL_VERSION_NUM >= 0x071304 + if (is_transport_allowed("http")) + allowed_protocols |= CURLPROTO_HTTP; + if (is_transport_allowed("https")) + allowed_protocols |= CURLPROTO_HTTPS; + if (is_transport_allowed("ftp")) + allowed_protocols |= CURLPROTO_FTP; + if (is_transport_allowed("ftps")) + allowed_protocols |= CURLPROTO_FTPS; + curl_easy_setopt(result, CURLOPT_REDIR_PROTOCOLS, allowed_protocols); +#else + if (transport_restrict_protocols()) + warning("protocol restrictions not applied to curl redirects because\n" + "your curl version is too old (>= 7.19.4)"); +#endif if (getenv("GIT_CURL_VERBOSE")) curl_easy_setopt(result, CURLOPT_VERBOSE, 1); -- 2.1.0