nvmet-tcp: add bounds check on Transfer Tag
[linux-block.git] / security / keys / permission.c
CommitLineData
2874c5fd 1// SPDX-License-Identifier: GPL-2.0-or-later
973c9f4f 2/* Key permission checking
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3 *
4 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.com)
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6 */
7
876979c9 8#include <linux/export.h>
29db9190 9#include <linux/security.h>
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10#include "internal.h"
11
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12/**
13 * key_task_permission - Check a key can be used
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14 * @key_ref: The key to check.
15 * @cred: The credentials to use.
8c0637e9 16 * @need_perm: The permission required.
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17 *
18 * Check to see whether permission is granted to use a key in the desired way,
19 * but permit the security modules to override.
20 *
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21 * The caller must hold either a ref on cred or must hold the RCU readlock.
22 *
23 * Returns 0 if successful, -EACCES if access is denied based on the
24 * permissions bits or the LSM check.
468ed2b0 25 */
d84f4f99 26int key_task_permission(const key_ref_t key_ref, const struct cred *cred,
8c0637e9 27 enum key_need_perm need_perm)
468ed2b0 28{
028db3e2 29 struct key *key;
8c0637e9 30 key_perm_t kperm, mask;
028db3e2 31 int ret;
468ed2b0 32
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33 switch (need_perm) {
34 default:
35 WARN_ON(1);
36 return -EACCES;
37 case KEY_NEED_UNLINK:
38 case KEY_SYSADMIN_OVERRIDE:
39 case KEY_AUTHTOKEN_OVERRIDE:
40 case KEY_DEFER_PERM_CHECK:
41 goto lsm;
42
43 case KEY_NEED_VIEW: mask = KEY_OTH_VIEW; break;
44 case KEY_NEED_READ: mask = KEY_OTH_READ; break;
45 case KEY_NEED_WRITE: mask = KEY_OTH_WRITE; break;
46 case KEY_NEED_SEARCH: mask = KEY_OTH_SEARCH; break;
47 case KEY_NEED_LINK: mask = KEY_OTH_LINK; break;
48 case KEY_NEED_SETATTR: mask = KEY_OTH_SETATTR; break;
49 }
50
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51 key = key_ref_to_ptr(key_ref);
52
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53 /* use the second 8-bits of permissions for keys the caller owns */
54 if (uid_eq(key->uid, cred->fsuid)) {
55 kperm = key->perm >> 16;
56 goto use_these_perms;
57 }
468ed2b0 58
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59 /* use the third 8-bits of permissions for keys the caller has a group
60 * membership in common with */
61 if (gid_valid(key->gid) && key->perm & KEY_GRP_ALL) {
62 if (gid_eq(key->gid, cred->fsgid)) {
63 kperm = key->perm >> 8;
64 goto use_these_perms;
65 }
468ed2b0 66
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67 ret = groups_search(cred->group_info, key->gid);
68 if (ret) {
69 kperm = key->perm >> 8;
70 goto use_these_perms;
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71 }
72 }
73
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74 /* otherwise use the least-significant 8-bits */
75 kperm = key->perm;
76
77use_these_perms:
c69e8d9c 78
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79 /* use the top 8-bits of permissions for keys the caller possesses
80 * - possessor permissions are additive with other permissions
81 */
82 if (is_key_possessed(key_ref))
83 kperm |= key->perm >> 24;
7ab501db 84
8c0637e9 85 if ((kperm & mask) != mask)
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86 return -EACCES;
87
88 /* let LSM be the final arbiter */
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89lsm:
90 return security_key_permission(key_ref, cred, need_perm);
a8b17ed0 91}
468ed2b0 92EXPORT_SYMBOL(key_task_permission);
b5f545c8 93
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94/**
95 * key_validate - Validate a key.
96 * @key: The key to be validated.
97 *
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98 * Check that a key is valid, returning 0 if the key is okay, -ENOKEY if the
99 * key is invalidated, -EKEYREVOKED if the key's type has been removed or if
100 * the key has been revoked or -EKEYEXPIRED if the key has expired.
b5f545c8 101 */
b404aef7 102int key_validate(const struct key *key)
b5f545c8 103{
1823d475 104 unsigned long flags = READ_ONCE(key->flags);
074d5898 105 time64_t expiry = READ_ONCE(key->expiry);
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106
107 if (flags & (1 << KEY_FLAG_INVALIDATED))
108 return -ENOKEY;
109
110 /* check it's still accessible */
111 if (flags & ((1 << KEY_FLAG_REVOKED) |
112 (1 << KEY_FLAG_DEAD)))
113 return -EKEYREVOKED;
114
115 /* check it hasn't expired */
1823d475 116 if (expiry) {
074d5898 117 if (ktime_get_real_seconds() >= expiry)
b404aef7 118 return -EKEYEXPIRED;
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119 }
120
b404aef7 121 return 0;
a8b17ed0 122}
b5f545c8 123EXPORT_SYMBOL(key_validate);