cred.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 * Landlock - Credential hooks
 4 *
 5 * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
 6 * Copyright © 2018-2020 ANSSI
 7 * Copyright © 2024-2025 Microsoft Corporation
 8 */
 9
10#include <linux/binfmts.h>
11#include <linux/cred.h>
12#include <linux/lsm_hooks.h>
13
14#include "common.h"
15#include "cred.h"
16#include "ruleset.h"
17#include "setup.h"
18
19static void hook_cred_transfer(struct cred *const new,
20			       const struct cred *const old)
21{
22	const struct landlock_cred_security *const old_llcred =
23		landlock_cred(old);
24
25	if (old_llcred->domain) {
26		landlock_get_ruleset(old_llcred->domain);
27		*landlock_cred(new) = *old_llcred;
28	}
29}
30
31static int hook_cred_prepare(struct cred *const new,
32			     const struct cred *const old, const gfp_t gfp)
33{
34	hook_cred_transfer(new, old);
35	return 0;
36}
37
38static void hook_cred_free(struct cred *const cred)
39{
40	struct landlock_ruleset *const dom = landlock_cred(cred)->domain;
41
42	if (dom)
43		landlock_put_ruleset_deferred(dom);
44}
45
46#ifdef CONFIG_AUDIT
47
48static int hook_bprm_creds_for_exec(struct linux_binprm *const bprm)
49{
50	/* Resets for each execution. */
51	landlock_cred(bprm->cred)->domain_exec = 0;
52	return 0;
53}
54
55#endif /* CONFIG_AUDIT */
56
57static struct security_hook_list landlock_hooks[] __ro_after_init = {
58	LSM_HOOK_INIT(cred_prepare, hook_cred_prepare),
59	LSM_HOOK_INIT(cred_transfer, hook_cred_transfer),
60	LSM_HOOK_INIT(cred_free, hook_cred_free),
61
62#ifdef CONFIG_AUDIT
63	LSM_HOOK_INIT(bprm_creds_for_exec, hook_bprm_creds_for_exec),
64#endif /* CONFIG_AUDIT */
65};
66
67__init void landlock_add_cred_hooks(void)
68{
69	security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks),
70			   &landlock_lsmid);
71}