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/idr.h>
17 #include <linux/slab.h>
18 #include <linux/spinlock.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_IDR(aa_secids);
33 static DEFINE_SPINLOCK(secid_lock);
34
35 /*
36 * TODO: allow policy to reserve a secid range?
37 * TODO: add secid pinning
38 * TODO: use secid_update in label replace
39 */
40
41 /**
42 * aa_secid_update - update a secid mapping to a new label
43 * @secid: secid to update
44 * @label: label the secid will now map to
45 */
aa_secid_update(u32 secid,struct aa_label * label)46 void aa_secid_update(u32 secid, struct aa_label *label)
47 {
48 unsigned long flags;
49
50 spin_lock_irqsave(&secid_lock, flags);
51 idr_replace(&aa_secids, label, secid);
52 spin_unlock_irqrestore(&secid_lock, flags);
53 }
54
55 /**
56 *
57 * see label for inverse aa_label_to_secid
58 */
aa_secid_to_label(u32 secid)59 struct aa_label *aa_secid_to_label(u32 secid)
60 {
61 struct aa_label *label;
62
63 rcu_read_lock();
64 label = idr_find(&aa_secids, secid);
65 rcu_read_unlock();
66
67 return label;
68 }
69
apparmor_secid_to_secctx(u32 secid,char ** secdata,u32 * seclen)70 int apparmor_secid_to_secctx(u32 secid, char **secdata, u32 *seclen)
71 {
72 /* TODO: cache secctx and ref count so we don't have to recreate */
73 struct aa_label *label = aa_secid_to_label(secid);
74 int len;
75
76 AA_BUG(!seclen);
77
78 if (!label)
79 return -EINVAL;
80
81 if (secdata)
82 len = aa_label_asxprint(secdata, root_ns, label,
83 FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
84 FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT,
85 GFP_ATOMIC);
86 else
87 len = aa_label_snxprint(NULL, 0, root_ns, label,
88 FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
89 FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT);
90 if (len < 0)
91 return -ENOMEM;
92
93 *seclen = len;
94
95 return 0;
96 }
97
apparmor_secctx_to_secid(const char * secdata,u32 seclen,u32 * secid)98 int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
99 {
100 struct aa_label *label;
101
102 label = aa_label_strn_parse(&root_ns->unconfined->label, secdata,
103 seclen, GFP_KERNEL, false, false);
104 if (IS_ERR(label))
105 return PTR_ERR(label);
106 *secid = label->secid;
107
108 return 0;
109 }
110
apparmor_release_secctx(char * secdata,u32 seclen)111 void apparmor_release_secctx(char *secdata, u32 seclen)
112 {
113 kfree(secdata);
114 }
115
116 /**
117 * aa_alloc_secid - allocate a new secid for a profile
118 * @label: the label to allocate a secid for
119 * @gfp: memory allocation flags
120 *
121 * Returns: 0 with @label->secid initialized
122 * <0 returns error with @label->secid set to AA_SECID_INVALID
123 */
aa_alloc_secid(struct aa_label * label,gfp_t gfp)124 int aa_alloc_secid(struct aa_label *label, gfp_t gfp)
125 {
126 unsigned long flags;
127 int ret;
128
129 idr_preload(gfp);
130 spin_lock_irqsave(&secid_lock, flags);
131 ret = idr_alloc(&aa_secids, label, AA_FIRST_SECID, 0, GFP_ATOMIC);
132 spin_unlock_irqrestore(&secid_lock, flags);
133 idr_preload_end();
134
135 if (ret < 0) {
136 label->secid = AA_SECID_INVALID;
137 return ret;
138 }
139
140 AA_BUG(ret == AA_SECID_INVALID);
141 label->secid = ret;
142 return 0;
143 }
144
145 /**
146 * aa_free_secid - free a secid
147 * @secid: secid to free
148 */
aa_free_secid(u32 secid)149 void aa_free_secid(u32 secid)
150 {
151 unsigned long flags;
152
153 spin_lock_irqsave(&secid_lock, flags);
154 idr_remove(&aa_secids, secid);
155 spin_unlock_irqrestore(&secid_lock, flags);
156 }
157
aa_secids_init(void)158 void aa_secids_init(void)
159 {
160 idr_init_base(&aa_secids, AA_FIRST_SECID);
161 }
162