xref: /linux/security/landlock/cred.c (revision 4f9786035f9e519db41375818e1d0b5f20da2f10)
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 
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 
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 
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 
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 
67 __init void landlock_add_cred_hooks(void)
68 {
69 	security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks),
70 			   &landlock_lsmid);
71 }
72