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 */
aa_secid_update(u32 secid,struct aa_label * label)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 *
58 * see label for inverse aa_label_to_secid
59 */
aa_secid_to_label(u32 secid)60 struct aa_label *aa_secid_to_label(u32 secid)
61 {
62 return xa_load(&aa_secids, secid);
63 }
64
apparmor_secid_to_secctx(u32 secid,char ** secdata,u32 * seclen)65 int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
66 {
67 /* TODO: cache secctx and ref count so we don't have to recreate */
68 struct aa_label *label = aa_secid_to_label(secid);
69 int flags = FLAG_VIEW_SUBNS | FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT;
70 int len;
71
72 AA_BUG(!seclen);
73
74 if (!label)
75 return -EINVAL;
76
77 if (apparmor_display_secid_mode)
78 flags |= FLAG_SHOW_MODE;
79
80 if (secdata)
81 len = aa_label_asxprint(secdata, root_ns, label,
82 flags, GFP_ATOMIC);
83 else
84 len = aa_label_snxprint(NULL, 0, root_ns, label, flags);
85
86 if (len < 0)
87 return -ENOMEM;
88
89 *seclen = len;
90
91 return 0;
92 }
93
apparmor_secctx_to_secid(const char * secdata,u32 seclen,u32 * secid)94 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
95 {
96 struct aa_label *label;
97
98 label = aa_label_strn_parse(&root_ns->unconfined->label, secdata,
99 seclen, GFP_KERNEL, false, false);
100 if (IS_ERR(label))
101 return PTR_ERR(label);
102 *secid = label->secid;
103
104 return 0;
105 }
106
apparmor_release_secctx(char * secdata,u32 seclen)107 void apparmor_release_secctx(char *secdata, u32 seclen)
108 {
109 kfree(secdata);
110 }
111
112 /**
113 * aa_alloc_secid - allocate a new secid for a profile
114 * @label: the label to allocate a secid for
115 * @gfp: memory allocation flags
116 *
117 * Returns: 0 with @label->secid initialized
118 * <0 returns error with @label->secid set to AA_SECID_INVALID
119 */
aa_alloc_secid(struct aa_label * label,gfp_t gfp)120 int aa_alloc_secid(struct aa_label *label, gfp_t gfp)
121 {
122 unsigned long flags;
123 int ret;
124
125 xa_lock_irqsave(&aa_secids, flags);
126 ret = __xa_alloc(&aa_secids, &label->secid, label,
127 XA_LIMIT(AA_FIRST_SECID, INT_MAX), gfp);
128 xa_unlock_irqrestore(&aa_secids, flags);
129
130 if (ret < 0) {
131 label->secid = AA_SECID_INVALID;
132 return ret;
133 }
134
135 return 0;
136 }
137
138 /**
139 * aa_free_secid - free a secid
140 * @secid: secid to free
141 */
aa_free_secid(u32 secid)142 void aa_free_secid(u32 secid)
143 {
144 unsigned long flags;
145
146 xa_lock_irqsave(&aa_secids, flags);
147 __xa_erase(&aa_secids, secid);
148 xa_unlock_irqrestore(&aa_secids, flags);
149 }
150