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
hook_cred_transfer(struct cred * const new,const struct cred * const old)19 static 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
hook_cred_prepare(struct cred * const new,const struct cred * const old,const gfp_t gfp)31 static 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
hook_cred_free(struct cred * const cred)38 static 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
hook_bprm_creds_for_exec(struct linux_binprm * const bprm)48 static 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
57 static 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
landlock_add_cred_hooks(void)67 __init void landlock_add_cred_hooks(void)
68 {
69 security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks),
70 &landlock_lsmid);
71 }
72