From 8db1e8743c0f1ed241f6a1b8bf55b6fef07d6751 Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Thu, 28 Mar 2024 19:21:06 +0100 Subject: clone: prevent hooks from running during a clone 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 `/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 --- hook.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) (limited to 'hook.c') diff --git a/hook.c b/hook.c index 22b274b60b..632b537b99 100644 --- a/hook.c +++ b/hook.c @@ -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; } -- cgit v1.3-6-g1900