xref: /linux/security/apparmor/secid.c (revision cdd5b5a9761fd66d17586e4f4ba6588c70e640ea)
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  * 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 	return xa_load(&aa_secids, secid);
62 }
63 
apparmor_secid_to_secctx(u32 secid,char ** secdata,u32 * seclen)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 
apparmor_secctx_to_secid(const char * secdata,u32 seclen,u32 * secid)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 
apparmor_release_secctx(char * secdata,u32 seclen)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  */
aa_alloc_secid(struct aa_label * label,gfp_t gfp)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  */
aa_free_secid(u32 secid)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