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
 32static DEFINE_IDR(aa_secids);
 33static 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 */
 46void 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 */
 59struct 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
 70int 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
 98int 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
111void 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 */
124int 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 */
149void 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
158void aa_secids_init(void)
159{
160	idr_init_base(&aa_secids, AA_FIRST_SECID);
161}