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authorJeff King <peff@peff.net>2015-09-16 13:12:52 -0400
committerJunio C Hamano <gitster@pobox.com>2015-09-23 11:35:48 -0700
commita5adaced2e13c135d5d9cc65be9eb95aa3bacedf (patch)
treee4ad0544170f80c65ee073d08d2974780be5d5df /transport.c
parentecad27cf98c391d5cfdc26ce0e442e02347baad0 (diff)
downloadgit-a5adaced2e13c135d5d9cc65be9eb95aa3bacedf.tar.gz
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 <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'transport.c')
-rw-r--r--transport.c21
1 files changed, 20 insertions, 1 deletions
diff --git a/transport.c b/transport.c
index 88bde1d85e..94fe8658f2 100644
--- a/transport.c
+++ b/transport.c
@@ -909,6 +909,20 @@ static int external_specification_len(const char *url)
return strchr(url, ':') - url;
}
+void transport_check_allowed(const char *type)
+{
+ struct string_list allowed = STRING_LIST_INIT_DUP;
+ const char *v = getenv("GIT_ALLOW_PROTOCOL");
+
+ if (!v)
+ return;
+
+ string_list_split(&allowed, v, ':', -1);
+ if (!unsorted_string_list_has_string(&allowed, type))
+ die("transport '%s' not allowed", type);
+ string_list_clear(&allowed, 0);
+}
+
struct transport *transport_get(struct remote *remote, const char *url)
{
const char *helper;
@@ -940,12 +954,14 @@ struct transport *transport_get(struct remote *remote, const char *url)
if (helper) {
transport_helper_init(ret, helper);
} else if (starts_with(url, "rsync:")) {
+ transport_check_allowed("rsync");
ret->get_refs_list = get_refs_via_rsync;
ret->fetch = fetch_objs_via_rsync;
ret->push = rsync_transport_push;
ret->smart_options = NULL;
} else if (url_is_local_not_ssh(url) && is_file(url) && is_bundle(url, 1)) {
struct bundle_transport_data *data = xcalloc(1, sizeof(*data));
+ transport_check_allowed("file");
ret->data = data;
ret->get_refs_list = get_refs_from_bundle;
ret->fetch = fetch_refs_from_bundle;
@@ -957,7 +973,10 @@ struct transport *transport_get(struct remote *remote, const char *url)
|| starts_with(url, "ssh://")
|| starts_with(url, "git+ssh://")
|| starts_with(url, "ssh+git://")) {
- /* These are builtin smart transports. */
+ /*
+ * These are builtin smart transports; "allowed" transports
+ * will be checked individually in git_connect.
+ */
struct git_transport_data *data = xcalloc(1, sizeof(*data));
ret->data = data;
ret->set_option = NULL;