1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * AppArmor security module
4 *
5 * This file contains AppArmor security identifier (secid) manipulation fns
6 *
7 * Copyright 2009-2017 Canonical Ltd.
8 *
9 * AppArmor allocates a unique secid for every label used. If a label
10 * is replaced it receives the secid of the label it is replacing.
11 */
12
13 #include <linux/errno.h>
14 #include <linux/err.h>
15 #include <linux/gfp.h>
16 #include <linux/slab.h>
17 #include <linux/spinlock.h>
18 #include <linux/xarray.h>
19
20 #include "include/cred.h"
21 #include "include/lib.h"
22 #include "include/secid.h"
23 #include "include/label.h"
24 #include "include/policy_ns.h"
25
26 /*
27 * secids - do not pin labels with a refcount. They rely on the label
28 * properly updating/freeing them
29 */
30 #define AA_FIRST_SECID 2
31
32 static DEFINE_XARRAY_FLAGS(aa_secids, XA_FLAGS_LOCK_IRQ | XA_FLAGS_TRACK_FREE);
33
34 int apparmor_display_secid_mode;
35
36 /*
37 * TODO: allow policy to reserve a secid range?
38 * TODO: add secid pinning
39 * TODO: use secid_update in label replace
40 */
41
42 /**
43 * aa_secid_update - update a secid mapping to a new label
44 * @secid: secid to update
45 * @label: label the secid will now map to
46 */
47 void aa_secid_update(u32 secid, struct aa_label *label)
48 {
49 unsigned long flags;
50
51 xa_lock_irqsave(&aa_secids, flags);
52 __xa_store(&aa_secids, secid, label, 0);
53 xa_unlock_irqrestore(&aa_secids, flags);
54 }
55
56 /*
57 * see label for inverse aa_label_to_secid
58 */
59 struct aa_label *aa_secid_to_label(u32 secid)
60 {
61 return xa_load(&aa_secids, secid);
62 }
63
64 int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
65 {
66 /* TODO: cache secctx and ref count so we don't have to recreate */
67 struct aa_label *label = aa_secid_to_label(secid);
68 int flags = FLAG_VIEW_SUBNS | FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT;
69 int len;
70
71 AA_BUG(!seclen);
72
73 if (!label)
74 return -EINVAL;
75
76 if (apparmor_display_secid_mode)
77 flags |= FLAG_SHOW_MODE;
78
79 if (secdata)
80 len = aa_label_asxprint(secdata, root_ns, label,
81 flags, GFP_ATOMIC);
82 else
83 len = aa_label_snxprint(NULL, 0, root_ns, label, flags);
84
85 if (len < 0)
86 return -ENOMEM;
87
88 *seclen = len;
89
90 return 0;
91 }
92
93 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
94 {
95 struct aa_label *label;
96
97 label = aa_label_strn_parse(&root_ns->unconfined->label, secdata,
98 seclen, GFP_KERNEL, false, false);
99 if (IS_ERR(label))
100 return PTR_ERR(label);
101 *secid = label->secid;
102
103 return 0;
104 }
105
106 void apparmor_release_secctx(char *secdata, u32 seclen)
107 {
108 kfree(secdata);
109 }
110
111 /**
112 * aa_alloc_secid - allocate a new secid for a profile
113 * @label: the label to allocate a secid for
114 * @gfp: memory allocation flags
115 *
116 * Returns: 0 with @label->secid initialized
117 * <0 returns error with @label->secid set to AA_SECID_INVALID
118 */
119 int aa_alloc_secid(struct aa_label *label, gfp_t gfp)
120 {
121 unsigned long flags;
122 int ret;
123
124 xa_lock_irqsave(&aa_secids, flags);
125 ret = __xa_alloc(&aa_secids, &label->secid, label,
126 XA_LIMIT(AA_FIRST_SECID, INT_MAX), gfp);
127 xa_unlock_irqrestore(&aa_secids, flags);
128
129 if (ret < 0) {
130 label->secid = AA_SECID_INVALID;
131 return ret;
132 }
133
134 return 0;
135 }
136
137 /**
138 * aa_free_secid - free a secid
139 * @secid: secid to free
140 */
141 void aa_free_secid(u32 secid)
142 {
143 unsigned long flags;
144
145 xa_lock_irqsave(&aa_secids, flags);
146 __xa_erase(&aa_secids, secid);
147 xa_unlock_irqrestore(&aa_secids, flags);
148 }
149
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