secid.c

  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 * see label for inverse aa_label_to_secid
 44 */
 45struct aa_label *aa_secid_to_label(u32 secid)
 46{
 47	return xa_load(&aa_secids, secid);
 48}
 49
 50static int apparmor_label_to_secctx(struct aa_label *label,
 51				    struct lsm_context *cp)
 52{
 53	/* TODO: cache secctx and ref count so we don't have to recreate */
 54	int flags = FLAG_VIEW_SUBNS | FLAG_HIDDEN_UNCONFINED | FLAG_ABS_ROOT;
 55	int len;
 56
 57	if (!label)
 58		return -EINVAL;
 59
 60	if (apparmor_display_secid_mode)
 61		flags |= FLAG_SHOW_MODE;
 62
 63	if (cp)
 64		len = aa_label_asxprint(&cp->context, root_ns, label,
 65					flags, GFP_ATOMIC);
 66	else
 67		len = aa_label_snxprint(NULL, 0, root_ns, label, flags);
 68
 69	if (len < 0)
 70		return -ENOMEM;
 71
 72	if (cp) {
 73		cp->len = len;
 74		cp->id = LSM_ID_APPARMOR;
 75	}
 76
 77	return len;
 78}
 79
 80int apparmor_secid_to_secctx(u32 secid, struct lsm_context *cp)
 81{
 82	struct aa_label *label = aa_secid_to_label(secid);
 83
 84	return apparmor_label_to_secctx(label, cp);
 85}
 86
 87int apparmor_lsmprop_to_secctx(struct lsm_prop *prop, struct lsm_context *cp)
 88{
 89	struct aa_label *label;
 90
 91	label = prop->apparmor.label;
 92
 93	return apparmor_label_to_secctx(label, cp);
 94}
 95
 96int apparmor_secctx_to_secid(const char *secdata, u32 seclen, u32 *secid)
 97{
 98	struct aa_label *label;
 99
100	label = aa_label_strn_parse(&root_ns->unconfined->label, secdata,
101				    seclen, GFP_KERNEL, false, false);
102	if (IS_ERR(label))
103		return PTR_ERR(label);
104	*secid = label->secid;
105
106	return 0;
107}
108
109void apparmor_release_secctx(struct lsm_context *cp)
110{
111	if (cp->id == LSM_ID_APPARMOR) {
112		kfree(cp->context);
113		cp->context = NULL;
114		cp->id = LSM_ID_UNDEF;
115	}
116}
117
118/**
119 * aa_alloc_secid - allocate a new secid for a profile
120 * @label: the label to allocate a secid for
121 * @gfp: memory allocation flags
122 *
123 * Returns: 0 with @label->secid initialized
124 *          <0 returns error with @label->secid set to AA_SECID_INVALID
125 */
126int aa_alloc_secid(struct aa_label *label, gfp_t gfp)
127{
128	unsigned long flags;
129	int ret;
130
131	xa_lock_irqsave(&aa_secids, flags);
132	ret = __xa_alloc(&aa_secids, &label->secid, label,
133			XA_LIMIT(AA_FIRST_SECID, INT_MAX), gfp);
134	xa_unlock_irqrestore(&aa_secids, flags);
135
136	if (ret < 0) {
137		label->secid = AA_SECID_INVALID;
138		return ret;
139	}
140
141	return 0;
142}
143
144/**
145 * aa_free_secid - free a secid
146 * @secid: secid to free
147 */
148void aa_free_secid(u32 secid)
149{
150	unsigned long flags;
151
152	xa_lock_irqsave(&aa_secids, flags);
153	__xa_erase(&aa_secids, secid);
154	xa_unlock_irqrestore(&aa_secids, flags);
155}