Previously the `GIT_ALLOW_PROTOCOL` environment variable was used to
specify a whitelist of protocols to be used in clone/fetch/push
commands. This patch introduces new configuration options for more
fine-grained control for allowing/disallowing protocols. This also has
the added benefit of allowing easier construction of a protocol
whitelist on systems where setting an environment variable is
non-trivial.
Now users can specify a policy to be used for each type of protocol via
the 'protocol.<name>.allow' config option. A default policy for all
unconfigured protocols can be set with the 'protocol.allow' config
option. If no user configured default is made git, by default, will
allow known-safe protocols (http, https, git, ssh, file), disallow
known-dangerous protocols (ext), and have a default policy of `user` for
all other protocols.
The supported policies are `always`, `never`, and `user`. The `user`
policy can be used to configure a protocol to be usable when explicitly
used by a user, while disallowing it for commands which run
clone/fetch/push commands without direct user intervention (e.g.
recursive initialization of submodules). Commands which can potentially
clone/fetch/push from untrusted repositories without user intervention
can export `GIT_PROTOCOL_FROM_USER` with a value of '0' to prevent
protocols configured to the `user` policy from being used.
Fix remote-ext tests to use the new config to allow the ext
protocol to be tested.
Based on a patch by Jeff King <peff@xxxxxxxx>
Signed-off-by: Brandon Williams <bmwill@xxxxxxxxxx>
---
Documentation/config.txt | 25 ++++++++
Documentation/git.txt | 21 ++++---
git-submodule.sh | 12 ++--
t/lib-proto-disable.sh | 129 +++++++++++++++++++++++++++++++++++++--
t/t5509-fetch-push-namespaces.sh | 1 +
t/t5802-connect-helper.sh | 1 +
transport.c | 75 ++++++++++++++++++++++-
7 files changed, 242 insertions(+), 22 deletions(-)
diff --git a/Documentation/config.txt b/Documentation/config.txt
index 27069ac..0b1c186 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -2308,6 +2308,31 @@ pretty.<name>::
Note that an alias with the same name as a built-in format
will be silently ignored.
+protocol.allow::
+ If set, provide a user defined default policy for all protocols which
+ don't explicitly have a policy (`protocol.<name>.allow`). By default,
+ if unset, known-safe protocols (http, https, git, ssh, file) have a
+ default policy of `always`, known-dangerous protocols (ext) have a
+ default policy of `never`, and all other protocols have a default
+ policy of `user`. Supported policies:
++
+--
+
+* `always` - protocol is always able to be used.
+
+* `never` - protocol is never able to be used.
+
+* `user` - protocol is only able to be used when `GIT_PROTOCOL_FROM_USER` is
+ either unset or has a value of 1. This policy should be used when you want a
+ protocol to be directly usable by the user but don't want it used by commands which
+ execute clone/fetch/push commands without user input, e.g. recursive
+ submodule initialization.
+
+--
+
+protocol.<name>.allow::
+ Set a policy to be used by protocol <name> with clone/fetch/push commands.
+
pull.ff::
By default, Git does not create an extra merge commit when merging
a commit that is a descendant of the current commit. Instead, the
diff --git a/Documentation/git.txt b/Documentation/git.txt
index ab7215e..c9823e3 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -1150,13 +1150,14 @@ of clones and fetches.
cloning a repository to make a backup).
`GIT_ALLOW_PROTOCOL`::
- If set, provide a colon-separated list of protocols which are
- allowed to be used with fetch/push/clone. This is useful to
- restrict recursive submodule initialization from an untrusted
- repository. Any protocol not mentioned will be disallowed (i.e.,
- this is a whitelist, not a blacklist). If the variable is not
- set at all, all protocols are enabled. The protocol names
- currently used by git are:
+ The preferred way to configure allowed protocols is done through the
+ config interface, though this setting takes precedences. See
+ linkgit:git-config[1] for more details. If set to a colon-separated
+ list of protocols, behave as if `protocol.allow` is set to `never`, and
+ each of the listed protocols has `protocol.<name>.allow` set to
+ `always`. In other words, any protocol not mentioned will be
+ disallowed (i.e., this is a whitelist, not a blacklist). The protocol
+ names currently used by git are:
- `file`: any local file-based path (including `file://` URLs,
or local paths)
@@ -1174,6 +1175,12 @@ of clones and fetches.
- any external helpers are named by their protocol (e.g., use
`hg` to allow the `git-remote-hg` helper)
+`GIT_PROTOCOL_FROM_USER`::
+ Set to 0 to prevent protocols used by fetch/push/clone which are
+ configured to the `user` state. This is useful to restrict recursive
+ submodule initialization from an untrusted repository or for programs
+ which feed potentially-untrusted URLS to git commands. See
+ linkgit:git-config[1] for more details.
Discussion[[Discussion]]
------------------------
diff --git a/git-submodule.sh b/git-submodule.sh
index a024a13..0a477b4 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -21,14 +21,10 @@ require_work_tree
wt_prefix=$(git rev-parse --show-prefix)
cd_to_toplevel
-# Restrict ourselves to a vanilla subset of protocols; the URLs
-# we get are under control of a remote repository, and we do not
-# want them kicking off arbitrary git-remote-* programs.
-#
-# If the user has already specified a set of allowed protocols,
-# we assume they know what they're doing and use that instead.
-: ${GIT_ALLOW_PROTOCOL=file:git:http:https:ssh}
-export GIT_ALLOW_PROTOCOL
+# Tell the rest of git that any URLs we get don't come
+# directly from the user, so it can apply policy as appropriate.
+GIT_PROTOCOL_FROM_USER=0
+export GIT_PROTOCOL_FROM_USER
command=
branch=
diff --git a/t/lib-proto-disable.sh b/t/lib-proto-disable.sh
index be88e9a..4b2db2f 100644
--- a/t/lib-proto-disable.sh
+++ b/t/lib-proto-disable.sh
@@ -1,10 +1,7 @@
# Test routines for checking protocol disabling.
-# test cloning a particular protocol
-# $1 - description of the protocol
-# $2 - machine-readable name of the protocol
-# $3 - the URL to try cloning
-test_proto () {
+# Test clone/fetch/push with GIT_ALLOW_PROTOCOL whitelist
+test_whitelist () {
desc=$1
proto=$2
url=$3
@@ -62,6 +59,128 @@ test_proto () {
test_must_fail git clone --bare "$url" tmp.git
)
'
+
+ test_expect_success "clone $desc (env var has precedence)" '
+ rm -rf tmp.git &&
+ (
+ GIT_ALLOW_PROTOCOL=none &&
+ export GIT_ALLOW_PROTOCOL &&
+ test_must_fail git -c protocol.$proto.allow=always clone --bare "$url" tmp.git
+ )
+ '
+}
+
+test_config () {
+ desc=$1
+ proto=$2
+ url=$3
+
+ # Test clone/fetch/push with protocol.<type>.allow config
+ test_expect_success "clone $desc (enabled with config)" '
+ rm -rf tmp.git &&
+ git -c protocol.$proto.allow=always clone --bare "$url" tmp.git
+ '
+
+ test_expect_success "fetch $desc (enabled)" '
+ git -C tmp.git -c protocol.$proto.allow=always fetch
+ '
+
+ test_expect_success "push $desc (enabled)" '
+ git -C tmp.git -c protocol.$proto.allow=always push origin HEAD:pushed
+ '
+
+ test_expect_success "push $desc (disabled)" '
+ test_must_fail git -C tmp.git -c protocol.$proto.allow=never push origin HEAD:pushed
+ '
+
+ test_expect_success "fetch $desc (disabled)" '
+ test_must_fail git -C tmp.git -c protocol.$proto.allow=never fetch
+ '
+
+ test_expect_success "clone $desc (disabled)" '
+ rm -rf tmp.git &&
+ test_must_fail git -c protocol.$proto.allow=never clone --bare "$url" tmp.git
+ '
+
+ # Test clone/fetch/push with protocol.user.allow and its env var
+ test_expect_success "clone $desc (enabled)" '
+ rm -rf tmp.git &&
+ git -c protocol.$proto.allow=user clone --bare "$url" tmp.git
+ '
+
+ test_expect_success "fetch $desc (enabled)" '
+ git -C tmp.git -c protocol.$proto.allow=user fetch
+ '
+
+ test_expect_success "push $desc (enabled)" '
+ git -C tmp.git -c protocol.$proto.allow=user push origin HEAD:pushed
+ '
+
+ test_expect_success "push $desc (disabled)" '
+ (
+ cd tmp.git &&
+ GIT_PROTOCOL_FROM_USER=0 &&
+ export GIT_PROTOCOL_FROM_USER &&
+ test_must_fail git -c protocol.$proto.allow=user push origin HEAD:pushed
+ )
+ '
+
+ test_expect_success "fetch $desc (disabled)" '
+ (
+ cd tmp.git &&
+ GIT_PROTOCOL_FROM_USER=0 &&
+ export GIT_PROTOCOL_FROM_USER &&
+ test_must_fail git -c protocol.$proto.allow=user fetch
+ )
+ '
+
+ test_expect_success "clone $desc (disabled)" '
+ rm -rf tmp.git &&
+ (
+ GIT_PROTOCOL_FROM_USER=0 &&
+ export GIT_PROTOCOL_FROM_USER &&
+ test_must_fail git -c protocol.$proto.allow=user clone --bare "$url" tmp.git
+ )
+ '
+
+ # Test clone/fetch/push with protocol.allow user defined default
+ test_expect_success "clone $desc (enabled)" '
+ rm -rf tmp.git &&
+ git config --global protocol.allow always &&
+ git clone --bare "$url" tmp.git
+ '
+
+ test_expect_success "fetch $desc (enabled)" '
+ git -C tmp.git fetch
+ '
+
+ test_expect_success "push $desc (enabled)" '
+ git -C tmp.git push origin HEAD:pushed
+ '
+
+ test_expect_success "push $desc (disabled)" '
+ git config --global protocol.allow never &&
+ test_must_fail git -C tmp.git push origin HEAD:pushed
+ '
+
+ test_expect_success "fetch $desc (disabled)" '
+ test_must_fail git -C tmp.git fetch
+ '
+
+ test_expect_success "clone $desc (disabled)" '
+ rm -rf tmp.git &&
+ test_must_fail git clone --bare "$url" tmp.git
+ '
+}
+
+# test cloning a particular protocol
+# $1 - description of the protocol
+# $2 - machine-readable name of the protocol
+# $3 - the URL to try cloning
+test_proto () {
+ test_whitelist "$@"
+
+ test_config "$@"
}
# set up an ssh wrapper that will access $host/$repo in the
diff --git a/t/t5509-fetch-push-namespaces.sh b/t/t5509-fetch-push-namespaces.sh
index bc44ac3..75c570a 100755
--- a/t/t5509-fetch-push-namespaces.sh
+++ b/t/t5509-fetch-push-namespaces.sh
@@ -4,6 +4,7 @@ test_description='fetch/push involving ref namespaces'
. ./test-lib.sh
test_expect_success setup '
+ git config --global protocol.ext.allow user &&
test_tick &&
git init original &&
(
diff --git a/t/t5802-connect-helper.sh b/t/t5802-connect-helper.sh
index b7a7f9d..c6c2661 100755
--- a/t/t5802-connect-helper.sh
+++ b/t/t5802-connect-helper.sh
@@ -4,6 +4,7 @@ test_description='ext::cmd remote "connect" helper'
. ./test-lib.sh
test_expect_success setup '
+ git config --global protocol.ext.allow user &&
test_tick &&
git commit --allow-empty -m initial &&
test_tick &&
diff --git a/transport.c b/transport.c
index d57e8de..2c0ec76 100644
--- a/transport.c
+++ b/transport.c
@@ -664,10 +664,81 @@ static const struct string_list *protocol_whitelist(void)
return enabled ? &allowed : NULL;
}
+enum protocol_allow_config {
+ PROTOCOL_ALLOW_NEVER = 0,
+ PROTOCOL_ALLOW_USER_ONLY,
+ PROTOCOL_ALLOW_ALWAYS
+};
+
+static enum protocol_allow_config parse_protocol_config(const char *key,
+ const char *value)
+{
+ if (!strcasecmp(value, "always"))
+ return PROTOCOL_ALLOW_ALWAYS;
+ else if (!strcasecmp(value, "never"))
+ return PROTOCOL_ALLOW_NEVER;
+ else if (!strcasecmp(value, "user"))
+ return PROTOCOL_ALLOW_USER_ONLY;
+
+ die("unknown value for config '%s': %s", key, value);
+}
+
+static enum protocol_allow_config get_protocol_config(const char *type)
+{
+ char *key = xstrfmt("protocol.%s.allow", type);
+ char *value;
+
+ /* first check the per-protocol config */
+ if (!git_config_get_string(key, &value)) {
+ enum protocol_allow_config ret =
+ parse_protocol_config(key, value);
+ free(key);
+ free(value);
+ return ret;
+ }
+ free(key);
+
+ /* if defined, fallback to user-defined default for unknown protocols */
+ if (!git_config_get_string("protocol.allow", &value)) {
+ enum protocol_allow_config ret =
+ parse_protocol_config("protocol.allow", value);
+ free(value);
+ return ret;
+ }
+
+ /* fallback to built-in defaults */
+ /* known safe */
+ if (!strcmp(type, "http") ||
+ !strcmp(type, "https") ||
+ !strcmp(type, "git") ||
+ !strcmp(type, "ssh") ||
+ !strcmp(type, "file"))
+ return PROTOCOL_ALLOW_ALWAYS;
+
+ /* known scary; err on the side of caution */
+ if (!strcmp(type, "ext"))
+ return PROTOCOL_ALLOW_NEVER;
+
+ /* unknown; by default let them be used only directly by the user */
+ return PROTOCOL_ALLOW_USER_ONLY;
+}
+
int is_transport_allowed(const char *type)
{
- const struct string_list *allowed = protocol_whitelist();
- return !allowed || string_list_has_string(allowed, type);
+ const struct string_list *whitelist = protocol_whitelist();
+ if (whitelist)
+ return string_list_has_string(whitelist, type);
+
+ switch (get_protocol_config(type)) {
+ case PROTOCOL_ALLOW_ALWAYS:
+ return 1;
+ case PROTOCOL_ALLOW_NEVER:
+ return 0;
+ case PROTOCOL_ALLOW_USER_ONLY:
+ return git_env_bool("GIT_PROTOCOL_FROM_USER", 1);
+ }
+
+ die("BUG: invalid protocol_allow_config type");
}
void transport_check_allowed(const char *type)
--
2.8.0.rc3.226.g39d4020