From a5adaced2e13c135d5d9cc65be9eb95aa3bacedf Mon Sep 17 00:00:00 2001 From: Jeff King Date: Wed, 16 Sep 2015 13:12:52 -0400 Subject: transport: add a protocol-whitelist environment variable If we are cloning an untrusted remote repository into a sandbox, we may also want to fetch remote submodules in order to get the complete view as intended by the other side. However, that opens us up to attacks where a malicious user gets us to clone something they would not otherwise have access to (this is not necessarily a problem by itself, but we may then act on the cloned contents in a way that exposes them to the attacker). Ideally such a setup would sandbox git entirely away from high-value items, but this is not always practical or easy to set up (e.g., OS network controls may block multiple protocols, and we would want to enable some but not others). We can help this case by providing a way to restrict particular protocols. We use a whitelist in the environment. This is more annoying to set up than a blacklist, but defaults to safety if the set of protocols git supports grows). If no whitelist is specified, we continue to default to allowing all protocols (this is an "unsafe" default, but since the minority of users will want this sandboxing effect, it is the only sensible one). A note on the tests: ideally these would all be in a single test file, but the git-daemon and httpd test infrastructure is an all-or-nothing proposition rather than a test-by-test prerequisite. By putting them all together, we would be unable to test the file-local code on machines without apache. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- transport.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'transport.h') diff --git a/transport.h b/transport.h index 3e0091eaa..f7df6ec1d 100644 --- a/transport.h +++ b/transport.h @@ -132,6 +132,13 @@ struct transport { /* Returns a transport suitable for the url */ struct transport *transport_get(struct remote *, const char *); +/* + * Check whether a transport is allowed by the environment, + * and die otherwise. type should generally be the URL scheme, + * as described in Documentation/git.txt + */ +void transport_check_allowed(const char *type); + /* Transport options which apply to git:// and scp-style URLs */ /* The program to use on the remote side to send a pack */ -- cgit v1.2.1 From 5088d3b38775f8ac12d7f77636775b16059b67ef Mon Sep 17 00:00:00 2001 From: Jeff King Date: Tue, 22 Sep 2015 18:03:49 -0400 Subject: transport: refactor protocol whitelist code The current callers only want to die when their transport is prohibited. But future callers want to query the mechanism without dying. Let's break out a few query functions, and also save the results in a static list so we don't have to re-parse for each query. Based-on-a-patch-by: Blake Burkhart Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- transport.h | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) (limited to 'transport.h') diff --git a/transport.h b/transport.h index f7df6ec1d..ed84da2aa 100644 --- a/transport.h +++ b/transport.h @@ -132,13 +132,24 @@ struct transport { /* Returns a transport suitable for the url */ struct transport *transport_get(struct remote *, const char *); +/* + * Check whether a transport is allowed by the environment. Type should + * generally be the URL scheme, as described in Documentation/git.txt + */ +int is_transport_allowed(const char *type); + /* * Check whether a transport is allowed by the environment, - * and die otherwise. type should generally be the URL scheme, - * as described in Documentation/git.txt + * and die otherwise. */ void transport_check_allowed(const char *type); +/* + * Returns true if the user has attempted to turn on protocol + * restrictions at all. + */ +int transport_restrict_protocols(void); + /* Transport options which apply to git:// and scp-style URLs */ /* The program to use on the remote side to send a pack */ -- cgit v1.2.1