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Revision 8db1e8743c0f1ed241f6a1b8bf55b6fef07d6751 authored by Johannes Schindelin on 28 March 2024, 18:21:06 UTC, committed by Johannes Schindelin on 19 April 2024, 10:38:23 UTC 
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
`<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>
1 parent 584de0b
Raw File
chdir-notify.c 
#include "cache.h"
#include "chdir-notify.h"
#include "list.h"
#include "strbuf.h"

struct chdir_notify_entry {
	const char *name;
	chdir_notify_callback cb;
	void *data;
	struct list_head list;
};
static LIST_HEAD(chdir_notify_entries);

void chdir_notify_register(const char *name,
			   chdir_notify_callback cb,
			   void *data)
{
	struct chdir_notify_entry *e = xmalloc(sizeof(*e));
	e->name = name;
	e->cb = cb;
	e->data = data;
	list_add_tail(&e->list, &chdir_notify_entries);
}

static void reparent_cb(const char *name,
			const char *old_cwd,
			const char *new_cwd,
			void *data)
{
	char **path = data;
	char *tmp = *path;

	if (!tmp)
		return;

	*path = reparent_relative_path(old_cwd, new_cwd, tmp);
	free(tmp);

	if (name) {
		trace_printf_key(&trace_setup_key,
				 "setup: reparent %s to '%s'",
				 name, *path);
	}
}

void chdir_notify_reparent(const char *name, char **path)
{
	chdir_notify_register(name, reparent_cb, path);
}

int chdir_notify(const char *new_cwd)
{
	struct strbuf old_cwd = STRBUF_INIT;
	struct list_head *pos;

	if (strbuf_getcwd(&old_cwd) < 0)
		return -1;
	if (chdir(new_cwd) < 0) {
		int saved_errno = errno;
		strbuf_release(&old_cwd);
		errno = saved_errno;
		return -1;
	}

	trace_printf_key(&trace_setup_key,
			 "setup: chdir from '%s' to '%s'",
			 old_cwd.buf, new_cwd);

	list_for_each(pos, &chdir_notify_entries) {
		struct chdir_notify_entry *e =
			list_entry(pos, struct chdir_notify_entry, list);
		e->cb(e->name, old_cwd.buf, new_cwd, e->data);
	}

	strbuf_release(&old_cwd);
	return 0;
}

char *reparent_relative_path(const char *old_cwd,
			     const char *new_cwd,
			     const char *path)
{
	char *ret, *full;

	if (is_absolute_path(path))
		return xstrdup(path);

	full = xstrfmt("%s/%s", old_cwd, path);
	ret = xstrdup(remove_leading_path(full, new_cwd));
	free(full);

	return ret;
}
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