mirrors/git
1
0
Fork 0
mirror of https://github.com/git/git.git synced 2024-10-28 12:59:41 +01:00
Code Activity

clone: prevent hooks from running during a clone

Browse source 
Critical security issues typically combine relatively common
vulnerabilities such as case confusion in file paths with other
weaknesses in order to raise the severity of the attack.

One such weakness that has haunted the Git project in many a
submodule-related CVE is that any hooks that are found are executed
during a clone operation. Examples are the `post-checkout` and
`fsmonitor` hooks.

However, Git's design calls for hooks to be disabled by default, as only
disabled example hooks are copied over from the templates in
`<prefix>/share/git-core/templates/`.

As a defense-in-depth measure, let's prevent those hooks from running.

Obviously, administrators can choose to drop enabled hooks into the
template directory, though, _and_ it is also possible to override
`core.hooksPath`, in which case the new check needs to be disabled.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This commit is contained in:
Johannes Schindelin 2024-03-28 19:21:06 +01:00
parent 584de0b4c2
commit 8db1e8743c
3 changed files with 94 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

12
builtin/clone.c
View file

@ -908,6 +908,8 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
int err = 0, complete_refs_before_fetch = 1;
int submodule_progress;
int filter_submodules = 0;
const char *template_dir;
char *template_dir_dup = NULL;
struct transport_ls_refs_options transport_ls_refs_options =
TRANSPORT_LS_REFS_OPTIONS_INIT;
@ -927,6 +929,13 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
usage_msg_opt(_("You must specify a repository to clone."),
builtin_clone_usage, builtin_clone_options);
xsetenv("GIT_CLONE_PROTECTION_ACTIVE", "true", 0 /* allow user override */);
template_dir = get_template_dir(option_template);
if (*template_dir && !is_absolute_path(template_dir))
template_dir = template_dir_dup =
absolute_pathdup(template_dir);
xsetenv("GIT_CLONE_TEMPLATE_DIR", template_dir, 1);
if (option_depth || option_since || option_not.nr)
deepen = 1;
if (option_single_branch == -1)
@ -1074,7 +1083,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
}
}
init_db(git_dir, real_git_dir, option_template, GIT_HASH_UNKNOWN, NULL,
init_db(git_dir, real_git_dir, template_dir, GIT_HASH_UNKNOWN, NULL,
INIT_DB_QUIET);
if (real_git_dir) {
@ -1392,6 +1401,7 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
free(unborn_head);
free(dir);
free(path);
free(template_dir_dup);
UNLEAK(repo);
junk_mode = JUNK_LEAVE_ALL;

32
hook.c
View file

@ -3,6 +3,30 @@
#include "run-command.h"
#include "config.h"
static int identical_to_template_hook(const char *name, const char *path)
{
const char *env = getenv("GIT_CLONE_TEMPLATE_DIR");
const char *template_dir = get_template_dir(env && *env ? env : NULL);
struct strbuf template_path = STRBUF_INIT;
int found_template_hook, ret;
strbuf_addf(&template_path, "%s/hooks/%s", template_dir, name);
found_template_hook = access(template_path.buf, X_OK) >= 0;
#ifdef STRIP_EXTENSION
if (!found_template_hook) {
strbuf_addstr(&template_path, STRIP_EXTENSION);
found_template_hook = access(template_path.buf, X_OK) >= 0;
}
#endif
if (!found_template_hook)
return 0;
ret = do_files_match(template_path.buf, path);
strbuf_release(&template_path);
return ret;
}
const char *find_hook(const char *name)
{
static struct strbuf path = STRBUF_INIT;
@ -38,6 +62,14 @@ const char *find_hook(const char *name)
}
return NULL;
}
if (!git_hooks_path && git_env_bool("GIT_CLONE_PROTECTION_ACTIVE", 0) &&
!identical_to_template_hook(name, path.buf))
die(_("active `%s` hook found during `git clone`:\n\t%s\n"
"For security reasons, this is disallowed by default.\n"
"If this is intentional and the hook should actually "
"be run, please\nrun the command again with "
"`GIT_CLONE_PROTECTION_ACTIVE=false`"),
name, path.buf);
return path.buf;
}

51
t/t5601-clone.sh
View file

@ -771,6 +771,57 @@ test_expect_success 'batch missing blob request does not inadvertently try to fe
git clone --filter=blob:limit=0 "file://$(pwd)/server" client
'
test_expect_success 'clone with init.templatedir runs hooks' '
git init tmpl/hooks &&
write_script tmpl/hooks/post-checkout <<-EOF &&
echo HOOK-RUN >&2
echo I was here >hook.run
EOF
git -C tmpl/hooks add . &&
test_tick &&
git -C tmpl/hooks commit -m post-checkout &&
test_when_finished "git config --global --unset init.templateDir || :" &&
test_when_finished "git config --unset init.templateDir || :" &&
(
sane_unset GIT_TEMPLATE_DIR &&
NO_SET_GIT_TEMPLATE_DIR=t &&
export NO_SET_GIT_TEMPLATE_DIR &&
git -c core.hooksPath="$(pwd)/tmpl/hooks" \
clone tmpl/hooks hook-run-hookspath 2>err &&
! grep "active .* hook found" err &&
test_path_is_file hook-run-hookspath/hook.run &&
git -c init.templateDir="$(pwd)/tmpl" \
clone tmpl/hooks hook-run-config 2>err &&
! grep "active .* hook found" err &&
test_path_is_file hook-run-config/hook.run &&
git clone --template=tmpl tmpl/hooks hook-run-option 2>err &&
! grep "active .* hook found" err &&
test_path_is_file hook-run-option/hook.run &&
git config --global init.templateDir "$(pwd)/tmpl" &&
git clone tmpl/hooks hook-run-global-config 2>err &&
git config --global --unset init.templateDir &&
! grep "active .* hook found" err &&
test_path_is_file hook-run-global-config/hook.run &&
# clone ignores local `init.templateDir`; need to create
# a new repository because we deleted `.git/` in the
# `setup` test case above
git init local-clone &&
cd local-clone &&
git config init.templateDir "$(pwd)/../tmpl" &&
git clone ../tmpl/hooks hook-run-local-config 2>err &&
git config --unset init.templateDir &&
! grep "active .* hook found" err &&
test_path_is_missing hook-run-local-config/hook.run
)
'
. "$TEST_DIRECTORY"/lib-httpd.sh
start_httpd