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 *
 58 * see label for inverse aa_label_to_secid
 59 */
 60struct aa_label *aa_secid_to_label(u32 secid)
 61{
 62	return xa_load(&aa_secids, secid);
 63}
 64
 65int 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
 94int 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
107void 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 */
120int 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 */
142void 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}