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
32static DEFINE_XARRAY_FLAGS(aa_secids, XA_FLAGS_LOCK_IRQ | XA_FLAGS_TRACK_FREE);
33
34int 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 */
47void 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 */
59struct aa_label *aa_secid_to_label(u32 secid)
60{
61	return xa_load(&aa_secids, secid);
62}
63
64int 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
93int 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
106void 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 */
119int 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 */
141void 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