Previously the `GIT_ALLOW_PROTOCOL` environment variable was used to specify a whitelist of protocols to be used in clone/fetch/pull 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 unknown 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 poliy 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/pull commands without direct user intervention (e.g. recursive initialization of submodules). Commands which can potentially clone/fetch/pull 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. Signed-off-by: Brandon Williams <bmw...@google.com> --- Documentation/config.txt | 25 ++++++++ Documentation/git.txt | 19 +++--- git-submodule.sh | 12 ++-- t/lib-proto-disable.sh | 132 +++++++++++++++++++++++++++++++++++---- t/t5509-fetch-push-namespaces.sh | 1 + t/t5802-connect-helper.sh | 1 + transport.c | 73 +++++++++++++++++++++- 7 files changed, 235 insertions(+), 28 deletions(-) diff --git a/Documentation/config.txt b/Documentation/config.txt index 27069ac..5d845c4 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 usable by the user but don't want it used by commands which + execute clone/fetch/pull commands without user input, e.g. recursive + submodule initialization. + +-- + +protocol.<name>.allow:: + Set a policy to be used by protocol <name> with clone/fetch/pull 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..ab25580 100644 --- a/Documentation/git.txt +++ b/Documentation/git.txt @@ -1150,13 +1150,13 @@ 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 new 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, provide a + colon-separated list of protocols which are allowed to be used with + fetch/push/clone. 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 +1174,11 @@ 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. 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 b0917d9..5950fbf 100644 --- a/t/lib-proto-disable.sh +++ b/t/lib-proto-disable.sh @@ -1,15 +1,12 @@ # 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 - test_expect_success "clone $1 (enabled)" ' + test_expect_success "clone $desc (enabled)" ' rm -rf tmp.git && ( GIT_ALLOW_PROTOCOL=$proto && @@ -18,7 +15,7 @@ test_proto () { ) ' - test_expect_success "fetch $1 (enabled)" ' + test_expect_success "fetch $desc (enabled)" ' ( cd tmp.git && GIT_ALLOW_PROTOCOL=$proto && @@ -27,7 +24,7 @@ test_proto () { ) ' - test_expect_success "push $1 (enabled)" ' + test_expect_success "push $desc (enabled)" ' ( cd tmp.git && GIT_ALLOW_PROTOCOL=$proto && @@ -36,7 +33,7 @@ test_proto () { ) ' - test_expect_success "push $1 (disabled)" ' + test_expect_success "push $desc (disabled)" ' ( cd tmp.git && GIT_ALLOW_PROTOCOL=none && @@ -45,7 +42,7 @@ test_proto () { ) ' - test_expect_success "fetch $1 (disabled)" ' + test_expect_success "fetch $desc (disabled)" ' ( cd tmp.git && GIT_ALLOW_PROTOCOL=none && @@ -54,7 +51,7 @@ test_proto () { ) ' - test_expect_success "clone $1 (disabled)" ' + test_expect_success "clone $desc (disabled)" ' rm -rf tmp.git && ( GIT_ALLOW_PROTOCOL=none && @@ -64,6 +61,119 @@ test_proto () { ' } +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 # trash directory, and enable it for subsequent tests. setup_ssh_wrapper () { 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..c2d0538 100644 --- a/transport.c +++ b/transport.c @@ -664,10 +664,79 @@ 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; + + 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, use user 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; + } + + /* 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