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