Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1222 insertions, 0 deletions

diff --git a/security/selinux/avc.c b/security/selinux/avc.c
new file mode 100644
index 000000000..9a43af0eb
--- /dev/null
+++ b/security/selinux/avc.c
@@ -0,0 +1,1222 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Implementation of the kernel access vector cache (AVC).
+ *
+ * Authors:  Stephen Smalley, <sds@tycho.nsa.gov>
+ *	     James Morris <jmorris@redhat.com>
+ *
+ * Update:   KaiGai, Kohei <kaigai@ak.jp.nec.com>
+ *	Replaced the avc_lock spinlock by RCU.
+ *
+ * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ */
+#include <linux/types.h>
+#include <linux/stddef.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/dcache.h>
+#include <linux/init.h>
+#include <linux/skbuff.h>
+#include <linux/percpu.h>
+#include <linux/list.h>
+#include <net/sock.h>
+#include <linux/un.h>
+#include <net/af_unix.h>
+#include <linux/ip.h>
+#include <linux/audit.h>
+#include <linux/ipv6.h>
+#include <net/ipv6.h>
+#include "avc.h"
+#include "avc_ss.h"
+#include "classmap.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/avc.h>
+
+#define AVC_CACHE_SLOTS			512
+#define AVC_DEF_CACHE_THRESHOLD		512
+#define AVC_CACHE_RECLAIM		16
+
+#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
+#define avc_cache_stats_incr(field)	this_cpu_inc(avc_cache_stats.field)
+#else
+#define avc_cache_stats_incr(field)	do {} while (0)
+#endif
+
+struct avc_entry {
+	u32			ssid;
+	u32			tsid;
+	u16			tclass;
+	struct av_decision	avd;
+	struct avc_xperms_node	*xp_node;
+};
+
+struct avc_node {
+	struct avc_entry	ae;
+	struct hlist_node	list; /* anchored in avc_cache->slots[i] */
+	struct rcu_head		rhead;
+};
+
+struct avc_xperms_decision_node {
+	struct extended_perms_decision xpd;
+	struct list_head xpd_list; /* list of extended_perms_decision */
+};
+
+struct avc_xperms_node {
+	struct extended_perms xp;
+	struct list_head xpd_head; /* list head of extended_perms_decision */
+};
+
+struct avc_cache {
+	struct hlist_head	slots[AVC_CACHE_SLOTS]; /* head for avc_node->list */
+	spinlock_t		slots_lock[AVC_CACHE_SLOTS]; /* lock for writes */
+	atomic_t		lru_hint;	/* LRU hint for reclaim scan */
+	atomic_t		active_nodes;
+	u32			latest_notif;	/* latest revocation notification */
+};
+
+struct avc_callback_node {
+	int (*callback) (u32 event);
+	u32 events;
+	struct avc_callback_node *next;
+};
+
+#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
+DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
+#endif
+
+struct selinux_avc {
+	unsigned int avc_cache_threshold;
+	struct avc_cache avc_cache;
+};
+
+static struct selinux_avc selinux_avc;
+
+void selinux_avc_init(struct selinux_avc **avc)
+{
+	int i;
+
+	selinux_avc.avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
+	for (i = 0; i < AVC_CACHE_SLOTS; i++) {
+		INIT_HLIST_HEAD(&selinux_avc.avc_cache.slots[i]);
+		spin_lock_init(&selinux_avc.avc_cache.slots_lock[i]);
+	}
+	atomic_set(&selinux_avc.avc_cache.active_nodes, 0);
+	atomic_set(&selinux_avc.avc_cache.lru_hint, 0);
+	*avc = &selinux_avc;
+}
+
+unsigned int avc_get_cache_threshold(struct selinux_avc *avc)
+{
+	return avc->avc_cache_threshold;
+}
+
+void avc_set_cache_threshold(struct selinux_avc *avc,
+			     unsigned int cache_threshold)
+{
+	avc->avc_cache_threshold = cache_threshold;
+}
+
+static struct avc_callback_node *avc_callbacks __ro_after_init;
+static struct kmem_cache *avc_node_cachep __ro_after_init;
+static struct kmem_cache *avc_xperms_data_cachep __ro_after_init;
+static struct kmem_cache *avc_xperms_decision_cachep __ro_after_init;
+static struct kmem_cache *avc_xperms_cachep __ro_after_init;
+
+static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
+{
+	return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
+}
+
+/**
+ * avc_init - Initialize the AVC.
+ *
+ * Initialize the access vector cache.
+ */
+void __init avc_init(void)
+{
+	avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
+					0, SLAB_PANIC, NULL);
+	avc_xperms_cachep = kmem_cache_create("avc_xperms_node",
+					sizeof(struct avc_xperms_node),
+					0, SLAB_PANIC, NULL);
+	avc_xperms_decision_cachep = kmem_cache_create(
+					"avc_xperms_decision_node",
+					sizeof(struct avc_xperms_decision_node),
+					0, SLAB_PANIC, NULL);
+	avc_xperms_data_cachep = kmem_cache_create("avc_xperms_data",
+					sizeof(struct extended_perms_data),
+					0, SLAB_PANIC, NULL);
+}
+
+int avc_get_hash_stats(struct selinux_avc *avc, char *page)
+{
+	int i, chain_len, max_chain_len, slots_used;
+	struct avc_node *node;
+	struct hlist_head *head;
+
+	rcu_read_lock();
+
+	slots_used = 0;
+	max_chain_len = 0;
+	for (i = 0; i < AVC_CACHE_SLOTS; i++) {
+		head = &avc->avc_cache.slots[i];
+		if (!hlist_empty(head)) {
+			slots_used++;
+			chain_len = 0;
+			hlist_for_each_entry_rcu(node, head, list)
+				chain_len++;
+			if (chain_len > max_chain_len)
+				max_chain_len = chain_len;
+		}
+	}
+
+	rcu_read_unlock();
+
+	return scnprintf(page, PAGE_SIZE, "entries: %d\nbuckets used: %d/%d\n"
+			 "longest chain: %d\n",
+			 atomic_read(&avc->avc_cache.active_nodes),
+			 slots_used, AVC_CACHE_SLOTS, max_chain_len);
+}
+
+/*
+ * using a linked list for extended_perms_decision lookup because the list is
+ * always small. i.e. less than 5, typically 1
+ */
+static struct extended_perms_decision *avc_xperms_decision_lookup(u8 driver,
+					struct avc_xperms_node *xp_node)
+{
+	struct avc_xperms_decision_node *xpd_node;
+
+	list_for_each_entry(xpd_node, &xp_node->xpd_head, xpd_list) {
+		if (xpd_node->xpd.driver == driver)
+			return &xpd_node->xpd;
+	}
+	return NULL;
+}
+
+static inline unsigned int
+avc_xperms_has_perm(struct extended_perms_decision *xpd,
+					u8 perm, u8 which)
+{
+	unsigned int rc = 0;
+
+	if ((which == XPERMS_ALLOWED) &&
+			(xpd->used & XPERMS_ALLOWED))
+		rc = security_xperm_test(xpd->allowed->p, perm);
+	else if ((which == XPERMS_AUDITALLOW) &&
+			(xpd->used & XPERMS_AUDITALLOW))
+		rc = security_xperm_test(xpd->auditallow->p, perm);
+	else if ((which == XPERMS_DONTAUDIT) &&
+			(xpd->used & XPERMS_DONTAUDIT))
+		rc = security_xperm_test(xpd->dontaudit->p, perm);
+	return rc;
+}
+
+static void avc_xperms_allow_perm(struct avc_xperms_node *xp_node,
+				u8 driver, u8 perm)
+{
+	struct extended_perms_decision *xpd;
+	security_xperm_set(xp_node->xp.drivers.p, driver);
+	xpd = avc_xperms_decision_lookup(driver, xp_node);
+	if (xpd && xpd->allowed)
+		security_xperm_set(xpd->allowed->p, perm);
+}
+
+static void avc_xperms_decision_free(struct avc_xperms_decision_node *xpd_node)
+{
+	struct extended_perms_decision *xpd;
+
+	xpd = &xpd_node->xpd;
+	if (xpd->allowed)
+		kmem_cache_free(avc_xperms_data_cachep, xpd->allowed);
+	if (xpd->auditallow)
+		kmem_cache_free(avc_xperms_data_cachep, xpd->auditallow);
+	if (xpd->dontaudit)
+		kmem_cache_free(avc_xperms_data_cachep, xpd->dontaudit);
+	kmem_cache_free(avc_xperms_decision_cachep, xpd_node);
+}
+
+static void avc_xperms_free(struct avc_xperms_node *xp_node)
+{
+	struct avc_xperms_decision_node *xpd_node, *tmp;
+
+	if (!xp_node)
+		return;
+
+	list_for_each_entry_safe(xpd_node, tmp, &xp_node->xpd_head, xpd_list) {
+		list_del(&xpd_node->xpd_list);
+		avc_xperms_decision_free(xpd_node);
+	}
+	kmem_cache_free(avc_xperms_cachep, xp_node);
+}
+
+static void avc_copy_xperms_decision(struct extended_perms_decision *dest,
+					struct extended_perms_decision *src)
+{
+	dest->driver = src->driver;
+	dest->used = src->used;
+	if (dest->used & XPERMS_ALLOWED)
+		memcpy(dest->allowed->p, src->allowed->p,
+				sizeof(src->allowed->p));
+	if (dest->used & XPERMS_AUDITALLOW)
+		memcpy(dest->auditallow->p, src->auditallow->p,
+				sizeof(src->auditallow->p));
+	if (dest->used & XPERMS_DONTAUDIT)
+		memcpy(dest->dontaudit->p, src->dontaudit->p,
+				sizeof(src->dontaudit->p));
+}
+
+/*
+ * similar to avc_copy_xperms_decision, but only copy decision
+ * information relevant to this perm
+ */
+static inline void avc_quick_copy_xperms_decision(u8 perm,
+			struct extended_perms_decision *dest,
+			struct extended_perms_decision *src)
+{
+	/*
+	 * compute index of the u32 of the 256 bits (8 u32s) that contain this
+	 * command permission
+	 */
+	u8 i = perm >> 5;
+
+	dest->used = src->used;
+	if (dest->used & XPERMS_ALLOWED)
+		dest->allowed->p[i] = src->allowed->p[i];
+	if (dest->used & XPERMS_AUDITALLOW)
+		dest->auditallow->p[i] = src->auditallow->p[i];
+	if (dest->used & XPERMS_DONTAUDIT)
+		dest->dontaudit->p[i] = src->dontaudit->p[i];
+}
+
+static struct avc_xperms_decision_node
+		*avc_xperms_decision_alloc(u8 which)
+{
+	struct avc_xperms_decision_node *xpd_node;
+	struct extended_perms_decision *xpd;
+
+	xpd_node = kmem_cache_zalloc(avc_xperms_decision_cachep,
+				     GFP_NOWAIT | __GFP_NOWARN);
+	if (!xpd_node)
+		return NULL;
+
+	xpd = &xpd_node->xpd;
+	if (which & XPERMS_ALLOWED) {
+		xpd->allowed = kmem_cache_zalloc(avc_xperms_data_cachep,
+						GFP_NOWAIT | __GFP_NOWARN);
+		if (!xpd->allowed)
+			goto error;
+	}
+	if (which & XPERMS_AUDITALLOW) {
+		xpd->auditallow = kmem_cache_zalloc(avc_xperms_data_cachep,
+						GFP_NOWAIT | __GFP_NOWARN);
+		if (!xpd->auditallow)
+			goto error;
+	}
+	if (which & XPERMS_DONTAUDIT) {
+		xpd->dontaudit = kmem_cache_zalloc(avc_xperms_data_cachep,
+						GFP_NOWAIT | __GFP_NOWARN);
+		if (!xpd->dontaudit)
+			goto error;
+	}
+	return xpd_node;
+error:
+	avc_xperms_decision_free(xpd_node);
+	return NULL;
+}
+
+static int avc_add_xperms_decision(struct avc_node *node,
+			struct extended_perms_decision *src)
+{
+	struct avc_xperms_decision_node *dest_xpd;
+
+	node->ae.xp_node->xp.len++;
+	dest_xpd = avc_xperms_decision_alloc(src->used);
+	if (!dest_xpd)
+		return -ENOMEM;
+	avc_copy_xperms_decision(&dest_xpd->xpd, src);
+	list_add(&dest_xpd->xpd_list, &node->ae.xp_node->xpd_head);
+	return 0;
+}
+
+static struct avc_xperms_node *avc_xperms_alloc(void)
+{
+	struct avc_xperms_node *xp_node;
+
+	xp_node = kmem_cache_zalloc(avc_xperms_cachep, GFP_NOWAIT | __GFP_NOWARN);
+	if (!xp_node)
+		return xp_node;
+	INIT_LIST_HEAD(&xp_node->xpd_head);
+	return xp_node;
+}
+
+static int avc_xperms_populate(struct avc_node *node,
+				struct avc_xperms_node *src)
+{
+	struct avc_xperms_node *dest;
+	struct avc_xperms_decision_node *dest_xpd;
+	struct avc_xperms_decision_node *src_xpd;
+
+	if (src->xp.len == 0)
+		return 0;
+	dest = avc_xperms_alloc();
+	if (!dest)
+		return -ENOMEM;
+
+	memcpy(dest->xp.drivers.p, src->xp.drivers.p, sizeof(dest->xp.drivers.p));
+	dest->xp.len = src->xp.len;
+
+	/* for each source xpd allocate a destination xpd and copy */
+	list_for_each_entry(src_xpd, &src->xpd_head, xpd_list) {
+		dest_xpd = avc_xperms_decision_alloc(src_xpd->xpd.used);
+		if (!dest_xpd)
+			goto error;
+		avc_copy_xperms_decision(&dest_xpd->xpd, &src_xpd->xpd);
+		list_add(&dest_xpd->xpd_list, &dest->xpd_head);
+	}
+	node->ae.xp_node = dest;
+	return 0;
+error:
+	avc_xperms_free(dest);
+	return -ENOMEM;
+
+}
+
+static inline u32 avc_xperms_audit_required(u32 requested,
+					struct av_decision *avd,
+					struct extended_perms_decision *xpd,
+					u8 perm,
+					int result,
+					u32 *deniedp)
+{
+	u32 denied, audited;
+
+	denied = requested & ~avd->allowed;
+	if (unlikely(denied)) {
+		audited = denied & avd->auditdeny;
+		if (audited && xpd) {
+			if (avc_xperms_has_perm(xpd, perm, XPERMS_DONTAUDIT))
+				audited &= ~requested;
+		}
+	} else if (result) {
+		audited = denied = requested;
+	} else {
+		audited = requested & avd->auditallow;
+		if (audited && xpd) {
+			if (!avc_xperms_has_perm(xpd, perm, XPERMS_AUDITALLOW))
+				audited &= ~requested;
+		}
+	}
+
+	*deniedp = denied;
+	return audited;
+}
+
+static inline int avc_xperms_audit(struct selinux_state *state,
+				   u32 ssid, u32 tsid, u16 tclass,
+				   u32 requested, struct av_decision *avd,
+				   struct extended_perms_decision *xpd,
+				   u8 perm, int result,
+				   struct common_audit_data *ad)
+{
+	u32 audited, denied;
+
+	audited = avc_xperms_audit_required(
+			requested, avd, xpd, perm, result, &denied);
+	if (likely(!audited))
+		return 0;
+	return slow_avc_audit(state, ssid, tsid, tclass, requested,
+			audited, denied, result, ad);
+}
+
+static void avc_node_free(struct rcu_head *rhead)
+{
+	struct avc_node *node = container_of(rhead, struct avc_node, rhead);
+	avc_xperms_free(node->ae.xp_node);
+	kmem_cache_free(avc_node_cachep, node);
+	avc_cache_stats_incr(frees);
+}
+
+static void avc_node_delete(struct selinux_avc *avc, struct avc_node *node)
+{
+	hlist_del_rcu(&node->list);
+	call_rcu(&node->rhead, avc_node_free);
+	atomic_dec(&avc->avc_cache.active_nodes);
+}
+
+static void avc_node_kill(struct selinux_avc *avc, struct avc_node *node)
+{
+	avc_xperms_free(node->ae.xp_node);
+	kmem_cache_free(avc_node_cachep, node);
+	avc_cache_stats_incr(frees);
+	atomic_dec(&avc->avc_cache.active_nodes);
+}
+
+static void avc_node_replace(struct selinux_avc *avc,
+			     struct avc_node *new, struct avc_node *old)
+{
+	hlist_replace_rcu(&old->list, &new->list);
+	call_rcu(&old->rhead, avc_node_free);
+	atomic_dec(&avc->avc_cache.active_nodes);
+}
+
+static inline int avc_reclaim_node(struct selinux_avc *avc)
+{
+	struct avc_node *node;
+	int hvalue, try, ecx;
+	unsigned long flags;
+	struct hlist_head *head;
+	spinlock_t *lock;
+
+	for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++) {
+		hvalue = atomic_inc_return(&avc->avc_cache.lru_hint) &
+			(AVC_CACHE_SLOTS - 1);
+		head = &avc->avc_cache.slots[hvalue];
+		lock = &avc->avc_cache.slots_lock[hvalue];
+
+		if (!spin_trylock_irqsave(lock, flags))
+			continue;
+
+		rcu_read_lock();
+		hlist_for_each_entry(node, head, list) {
+			avc_node_delete(avc, node);
+			avc_cache_stats_incr(reclaims);
+			ecx++;
+			if (ecx >= AVC_CACHE_RECLAIM) {
+				rcu_read_unlock();
+				spin_unlock_irqrestore(lock, flags);
+				goto out;
+			}
+		}
+		rcu_read_unlock();
+		spin_unlock_irqrestore(lock, flags);
+	}
+out:
+	return ecx;
+}
+
+static struct avc_node *avc_alloc_node(struct selinux_avc *avc)
+{
+	struct avc_node *node;
+
+	node = kmem_cache_zalloc(avc_node_cachep, GFP_NOWAIT | __GFP_NOWARN);
+	if (!node)
+		goto out;
+
+	INIT_HLIST_NODE(&node->list);
+	avc_cache_stats_incr(allocations);
+
+	if (atomic_inc_return(&avc->avc_cache.active_nodes) >
+	    avc->avc_cache_threshold)
+		avc_reclaim_node(avc);
+
+out:
+	return node;
+}
+
+static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct av_decision *avd)
+{
+	node->ae.ssid = ssid;
+	node->ae.tsid = tsid;
+	node->ae.tclass = tclass;
+	memcpy(&node->ae.avd, avd, sizeof(node->ae.avd));
+}
+
+static inline struct avc_node *avc_search_node(struct selinux_avc *avc,
+					       u32 ssid, u32 tsid, u16 tclass)
+{
+	struct avc_node *node, *ret = NULL;
+	int hvalue;
+	struct hlist_head *head;
+
+	hvalue = avc_hash(ssid, tsid, tclass);
+	head = &avc->avc_cache.slots[hvalue];
+	hlist_for_each_entry_rcu(node, head, list) {
+		if (ssid == node->ae.ssid &&
+		    tclass == node->ae.tclass &&
+		    tsid == node->ae.tsid) {
+			ret = node;
+			break;
+		}
+	}
+
+	return ret;
+}
+
+/**
+ * avc_lookup - Look up an AVC entry.
+ * @avc: the access vector cache
+ * @ssid: source security identifier
+ * @tsid: target security identifier
+ * @tclass: target security class
+ *
+ * Look up an AVC entry that is valid for the
+ * (@ssid, @tsid), interpreting the permissions
+ * based on @tclass.  If a valid AVC entry exists,
+ * then this function returns the avc_node.
+ * Otherwise, this function returns NULL.
+ */
+static struct avc_node *avc_lookup(struct selinux_avc *avc,
+				   u32 ssid, u32 tsid, u16 tclass)
+{
+	struct avc_node *node;
+
+	avc_cache_stats_incr(lookups);
+	node = avc_search_node(avc, ssid, tsid, tclass);
+
+	if (node)
+		return node;
+
+	avc_cache_stats_incr(misses);
+	return NULL;
+}
+
+static int avc_latest_notif_update(struct selinux_avc *avc,
+				   int seqno, int is_insert)
+{
+	int ret = 0;
+	static DEFINE_SPINLOCK(notif_lock);
+	unsigned long flag;
+
+	spin_lock_irqsave(&notif_lock, flag);
+	if (is_insert) {
+		if (seqno < avc->avc_cache.latest_notif) {
+			pr_warn("SELinux: avc:  seqno %d < latest_notif %d\n",
+			       seqno, avc->avc_cache.latest_notif);
+			ret = -EAGAIN;
+		}
+	} else {
+		if (seqno > avc->avc_cache.latest_notif)
+			avc->avc_cache.latest_notif = seqno;
+	}
+	spin_unlock_irqrestore(&notif_lock, flag);
+
+	return ret;
+}
+
+/**
+ * avc_insert - Insert an AVC entry.
+ * @avc: the access vector cache
+ * @ssid: source security identifier
+ * @tsid: target security identifier
+ * @tclass: target security class
+ * @avd: resulting av decision
+ * @xp_node: resulting extended permissions
+ *
+ * Insert an AVC entry for the SID pair
+ * (@ssid, @tsid) and class @tclass.
+ * The access vectors and the sequence number are
+ * normally provided by the security server in
+ * response to a security_compute_av() call.  If the
+ * sequence number @avd->seqno is not less than the latest
+ * revocation notification, then the function copies
+ * the access vectors into a cache entry, returns
+ * avc_node inserted. Otherwise, this function returns NULL.
+ */
+static struct avc_node *avc_insert(struct selinux_avc *avc,
+				   u32 ssid, u32 tsid, u16 tclass,
+				   struct av_decision *avd,
+				   struct avc_xperms_node *xp_node)
+{
+	struct avc_node *pos, *node = NULL;
+	int hvalue;
+	unsigned long flag;
+	spinlock_t *lock;
+	struct hlist_head *head;
+
+	if (avc_latest_notif_update(avc, avd->seqno, 1))
+		return NULL;
+
+	node = avc_alloc_node(avc);
+	if (!node)
+		return NULL;
+
+	avc_node_populate(node, ssid, tsid, tclass, avd);
+	if (avc_xperms_populate(node, xp_node)) {
+		avc_node_kill(avc, node);
+		return NULL;
+	}
+
+	hvalue = avc_hash(ssid, tsid, tclass);
+	head = &avc->avc_cache.slots[hvalue];
+	lock = &avc->avc_cache.slots_lock[hvalue];
+	spin_lock_irqsave(lock, flag);
+	hlist_for_each_entry(pos, head, list) {
+		if (pos->ae.ssid == ssid &&
+			pos->ae.tsid == tsid &&
+			pos->ae.tclass == tclass) {
+			avc_node_replace(avc, node, pos);
+			goto found;
+		}
+	}
+	hlist_add_head_rcu(&node->list, head);
+found:
+	spin_unlock_irqrestore(lock, flag);
+	return node;
+}
+
+/**
+ * avc_audit_pre_callback - SELinux specific information
+ * will be called by generic audit code
+ * @ab: the audit buffer
+ * @a: audit_data
+ */
+static void avc_audit_pre_callback(struct audit_buffer *ab, void *a)
+{
+	struct common_audit_data *ad = a;
+	struct selinux_audit_data *sad = ad->selinux_audit_data;
+	u32 av = sad->audited;
+	const char *const *perms;
+	int i, perm;
+
+	audit_log_format(ab, "avc:  %s ", sad->denied ? "denied" : "granted");
+
+	if (av == 0) {
+		audit_log_format(ab, " null");
+		return;
+	}
+
+	perms = secclass_map[sad->tclass-1].perms;
+
+	audit_log_format(ab, " {");
+	i = 0;
+	perm = 1;
+	while (i < (sizeof(av) * 8)) {
+		if ((perm & av) && perms[i]) {
+			audit_log_format(ab, " %s", perms[i]);
+			av &= ~perm;
+		}
+		i++;
+		perm <<= 1;
+	}
+
+	if (av)
+		audit_log_format(ab, " 0x%x", av);
+
+	audit_log_format(ab, " } for ");
+}
+
+/**
+ * avc_audit_post_callback - SELinux specific information
+ * will be called by generic audit code
+ * @ab: the audit buffer
+ * @a: audit_data
+ */
+static void avc_audit_post_callback(struct audit_buffer *ab, void *a)
+{
+	struct common_audit_data *ad = a;
+	struct selinux_audit_data *sad = ad->selinux_audit_data;
+	char *scontext = NULL;
+	char *tcontext = NULL;
+	const char *tclass = NULL;
+	u32 scontext_len;
+	u32 tcontext_len;
+	int rc;
+
+	rc = security_sid_to_context(sad->state, sad->ssid, &scontext,
+				     &scontext_len);
+	if (rc)
+		audit_log_format(ab, " ssid=%d", sad->ssid);
+	else
+		audit_log_format(ab, " scontext=%s", scontext);
+
+	rc = security_sid_to_context(sad->state, sad->tsid, &tcontext,
+				     &tcontext_len);
+	if (rc)
+		audit_log_format(ab, " tsid=%d", sad->tsid);
+	else
+		audit_log_format(ab, " tcontext=%s", tcontext);
+
+	tclass = secclass_map[sad->tclass-1].name;
+	audit_log_format(ab, " tclass=%s", tclass);
+
+	if (sad->denied)
+		audit_log_format(ab, " permissive=%u", sad->result ? 0 : 1);
+
+	trace_selinux_audited(sad, scontext, tcontext, tclass);
+	kfree(tcontext);
+	kfree(scontext);
+
+	/* in case of invalid context report also the actual context string */
+	rc = security_sid_to_context_inval(sad->state, sad->ssid, &scontext,
+					   &scontext_len);
+	if (!rc && scontext) {
+		if (scontext_len && scontext[scontext_len - 1] == '\0')
+			scontext_len--;
+		audit_log_format(ab, " srawcon=");
+		audit_log_n_untrustedstring(ab, scontext, scontext_len);
+		kfree(scontext);
+	}
+
+	rc = security_sid_to_context_inval(sad->state, sad->tsid, &scontext,
+					   &scontext_len);
+	if (!rc && scontext) {
+		if (scontext_len && scontext[scontext_len - 1] == '\0')
+			scontext_len--;
+		audit_log_format(ab, " trawcon=");
+		audit_log_n_untrustedstring(ab, scontext, scontext_len);
+		kfree(scontext);
+	}
+}
+
+/*
+ * This is the slow part of avc audit with big stack footprint.
+ * Note that it is non-blocking and can be called from under
+ * rcu_read_lock().
+ */
+noinline int slow_avc_audit(struct selinux_state *state,
+			    u32 ssid, u32 tsid, u16 tclass,
+			    u32 requested, u32 audited, u32 denied, int result,
+			    struct common_audit_data *a)
+{
+	struct common_audit_data stack_data;
+	struct selinux_audit_data sad;
+
+	if (WARN_ON(!tclass || tclass >= ARRAY_SIZE(secclass_map)))
+		return -EINVAL;
+
+	if (!a) {
+		a = &stack_data;
+		a->type = LSM_AUDIT_DATA_NONE;
+	}
+
+	sad.tclass = tclass;
+	sad.requested = requested;
+	sad.ssid = ssid;
+	sad.tsid = tsid;
+	sad.audited = audited;
+	sad.denied = denied;
+	sad.result = result;
+	sad.state = state;
+
+	a->selinux_audit_data = &sad;
+
+	common_lsm_audit(a, avc_audit_pre_callback, avc_audit_post_callback);
+	return 0;
+}
+
+/**
+ * avc_add_callback - Register a callback for security events.
+ * @callback: callback function
+ * @events: security events
+ *
+ * Register a callback function for events in the set @events.
+ * Returns %0 on success or -%ENOMEM if insufficient memory
+ * exists to add the callback.
+ */
+int __init avc_add_callback(int (*callback)(u32 event), u32 events)
+{
+	struct avc_callback_node *c;
+	int rc = 0;
+
+	c = kmalloc(sizeof(*c), GFP_KERNEL);
+	if (!c) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	c->callback = callback;
+	c->events = events;
+	c->next = avc_callbacks;
+	avc_callbacks = c;
+out:
+	return rc;
+}
+
+/**
+ * avc_update_node - Update an AVC entry
+ * @avc: the access vector cache
+ * @event : Updating event
+ * @perms : Permission mask bits
+ * @driver: xperm driver information
+ * @xperm: xperm permissions
+ * @ssid: AVC entry source sid
+ * @tsid: AVC entry target sid
+ * @tclass : AVC entry target object class
+ * @seqno : sequence number when decision was made
+ * @xpd: extended_perms_decision to be added to the node
+ * @flags: the AVC_* flags, e.g. AVC_EXTENDED_PERMS, or 0.
+ *
+ * if a valid AVC entry doesn't exist,this function returns -ENOENT.
+ * if kmalloc() called internal returns NULL, this function returns -ENOMEM.
+ * otherwise, this function updates the AVC entry. The original AVC-entry object
+ * will release later by RCU.
+ */
+static int avc_update_node(struct selinux_avc *avc,
+			   u32 event, u32 perms, u8 driver, u8 xperm, u32 ssid,
+			   u32 tsid, u16 tclass, u32 seqno,
+			   struct extended_perms_decision *xpd,
+			   u32 flags)
+{
+	int hvalue, rc = 0;
+	unsigned long flag;
+	struct avc_node *pos, *node, *orig = NULL;
+	struct hlist_head *head;
+	spinlock_t *lock;
+
+	node = avc_alloc_node(avc);
+	if (!node) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	/* Lock the target slot */
+	hvalue = avc_hash(ssid, tsid, tclass);
+
+	head = &avc->avc_cache.slots[hvalue];
+	lock = &avc->avc_cache.slots_lock[hvalue];
+
+	spin_lock_irqsave(lock, flag);
+
+	hlist_for_each_entry(pos, head, list) {
+		if (ssid == pos->ae.ssid &&
+		    tsid == pos->ae.tsid &&
+		    tclass == pos->ae.tclass &&
+		    seqno == pos->ae.avd.seqno){
+			orig = pos;
+			break;
+		}
+	}
+
+	if (!orig) {
+		rc = -ENOENT;
+		avc_node_kill(avc, node);
+		goto out_unlock;
+	}
+
+	/*
+	 * Copy and replace original node.
+	 */
+
+	avc_node_populate(node, ssid, tsid, tclass, &orig->ae.avd);
+
+	if (orig->ae.xp_node) {
+		rc = avc_xperms_populate(node, orig->ae.xp_node);
+		if (rc) {
+			avc_node_kill(avc, node);
+			goto out_unlock;
+		}
+	}
+
+	switch (event) {
+	case AVC_CALLBACK_GRANT:
+		node->ae.avd.allowed |= perms;
+		if (node->ae.xp_node && (flags & AVC_EXTENDED_PERMS))
+			avc_xperms_allow_perm(node->ae.xp_node, driver, xperm);
+		break;
+	case AVC_CALLBACK_TRY_REVOKE:
+	case AVC_CALLBACK_REVOKE:
+		node->ae.avd.allowed &= ~perms;
+		break;
+	case AVC_CALLBACK_AUDITALLOW_ENABLE:
+		node->ae.avd.auditallow |= perms;
+		break;
+	case AVC_CALLBACK_AUDITALLOW_DISABLE:
+		node->ae.avd.auditallow &= ~perms;
+		break;
+	case AVC_CALLBACK_AUDITDENY_ENABLE:
+		node->ae.avd.auditdeny |= perms;
+		break;
+	case AVC_CALLBACK_AUDITDENY_DISABLE:
+		node->ae.avd.auditdeny &= ~perms;
+		break;
+	case AVC_CALLBACK_ADD_XPERMS:
+		avc_add_xperms_decision(node, xpd);
+		break;
+	}
+	avc_node_replace(avc, node, orig);
+out_unlock:
+	spin_unlock_irqrestore(lock, flag);
+out:
+	return rc;
+}
+
+/**
+ * avc_flush - Flush the cache
+ * @avc: the access vector cache
+ */
+static void avc_flush(struct selinux_avc *avc)
+{
+	struct hlist_head *head;
+	struct avc_node *node;
+	spinlock_t *lock;
+	unsigned long flag;
+	int i;
+
+	for (i = 0; i < AVC_CACHE_SLOTS; i++) {
+		head = &avc->avc_cache.slots[i];
+		lock = &avc->avc_cache.slots_lock[i];
+
+		spin_lock_irqsave(lock, flag);
+		/*
+		 * With preemptable RCU, the outer spinlock does not
+		 * prevent RCU grace periods from ending.
+		 */
+		rcu_read_lock();
+		hlist_for_each_entry(node, head, list)
+			avc_node_delete(avc, node);
+		rcu_read_unlock();
+		spin_unlock_irqrestore(lock, flag);
+	}
+}
+
+/**
+ * avc_ss_reset - Flush the cache and revalidate migrated permissions.
+ * @avc: the access vector cache
+ * @seqno: policy sequence number
+ */
+int avc_ss_reset(struct selinux_avc *avc, u32 seqno)
+{
+	struct avc_callback_node *c;
+	int rc = 0, tmprc;
+
+	avc_flush(avc);
+
+	for (c = avc_callbacks; c; c = c->next) {
+		if (c->events & AVC_CALLBACK_RESET) {
+			tmprc = c->callback(AVC_CALLBACK_RESET);
+			/* save the first error encountered for the return
+			   value and continue processing the callbacks */
+			if (!rc)
+				rc = tmprc;
+		}
+	}
+
+	avc_latest_notif_update(avc, seqno, 0);
+	return rc;
+}
+
+/*
+ * Slow-path helper function for avc_has_perm_noaudit,
+ * when the avc_node lookup fails. We get called with
+ * the RCU read lock held, and need to return with it
+ * still held, but drop if for the security compute.
+ *
+ * Don't inline this, since it's the slow-path and just
+ * results in a bigger stack frame.
+ */
+static noinline
+struct avc_node *avc_compute_av(struct selinux_state *state,
+				u32 ssid, u32 tsid,
+				u16 tclass, struct av_decision *avd,
+				struct avc_xperms_node *xp_node)
+{
+	rcu_read_unlock();
+	INIT_LIST_HEAD(&xp_node->xpd_head);
+	security_compute_av(state, ssid, tsid, tclass, avd, &xp_node->xp);
+	rcu_read_lock();
+	return avc_insert(state->avc, ssid, tsid, tclass, avd, xp_node);
+}
+
+static noinline int avc_denied(struct selinux_state *state,
+			       u32 ssid, u32 tsid,
+			       u16 tclass, u32 requested,
+			       u8 driver, u8 xperm, unsigned int flags,
+			       struct av_decision *avd)
+{
+	if (flags & AVC_STRICT)
+		return -EACCES;
+
+	if (enforcing_enabled(state) &&
+	    !(avd->flags & AVD_FLAGS_PERMISSIVE))
+		return -EACCES;
+
+	avc_update_node(state->avc, AVC_CALLBACK_GRANT, requested, driver,
+			xperm, ssid, tsid, tclass, avd->seqno, NULL, flags);
+	return 0;
+}
+
+/*
+ * The avc extended permissions logic adds an additional 256 bits of
+ * permissions to an avc node when extended permissions for that node are
+ * specified in the avtab. If the additional 256 permissions is not adequate,
+ * as-is the case with ioctls, then multiple may be chained together and the
+ * driver field is used to specify which set contains the permission.
+ */
+int avc_has_extended_perms(struct selinux_state *state,
+			   u32 ssid, u32 tsid, u16 tclass, u32 requested,
+			   u8 driver, u8 xperm, struct common_audit_data *ad)
+{
+	struct avc_node *node;
+	struct av_decision avd;
+	u32 denied;
+	struct extended_perms_decision local_xpd;
+	struct extended_perms_decision *xpd = NULL;
+	struct extended_perms_data allowed;
+	struct extended_perms_data auditallow;
+	struct extended_perms_data dontaudit;
+	struct avc_xperms_node local_xp_node;
+	struct avc_xperms_node *xp_node;
+	int rc = 0, rc2;
+
+	xp_node = &local_xp_node;
+	if (WARN_ON(!requested))
+		return -EACCES;
+
+	rcu_read_lock();
+
+	node = avc_lookup(state->avc, ssid, tsid, tclass);
+	if (unlikely(!node)) {
+		avc_compute_av(state, ssid, tsid, tclass, &avd, xp_node);
+	} else {
+		memcpy(&avd, &node->ae.avd, sizeof(avd));
+		xp_node = node->ae.xp_node;
+	}
+	/* if extended permissions are not defined, only consider av_decision */
+	if (!xp_node || !xp_node->xp.len)
+		goto decision;
+
+	local_xpd.allowed = &allowed;
+	local_xpd.auditallow = &auditallow;
+	local_xpd.dontaudit = &dontaudit;
+
+	xpd = avc_xperms_decision_lookup(driver, xp_node);
+	if (unlikely(!xpd)) {
+		/*
+		 * Compute the extended_perms_decision only if the driver
+		 * is flagged
+		 */
+		if (!security_xperm_test(xp_node->xp.drivers.p, driver)) {
+			avd.allowed &= ~requested;
+			goto decision;
+		}
+		rcu_read_unlock();
+		security_compute_xperms_decision(state, ssid, tsid, tclass,
+						 driver, &local_xpd);
+		rcu_read_lock();
+		avc_update_node(state->avc, AVC_CALLBACK_ADD_XPERMS, requested,
+				driver, xperm, ssid, tsid, tclass, avd.seqno,
+				&local_xpd, 0);
+	} else {
+		avc_quick_copy_xperms_decision(xperm, &local_xpd, xpd);
+	}
+	xpd = &local_xpd;
+
+	if (!avc_xperms_has_perm(xpd, xperm, XPERMS_ALLOWED))
+		avd.allowed &= ~requested;
+
+decision:
+	denied = requested & ~(avd.allowed);
+	if (unlikely(denied))
+		rc = avc_denied(state, ssid, tsid, tclass, requested,
+				driver, xperm, AVC_EXTENDED_PERMS, &avd);
+
+	rcu_read_unlock();
+
+	rc2 = avc_xperms_audit(state, ssid, tsid, tclass, requested,
+			&avd, xpd, xperm, rc, ad);
+	if (rc2)
+		return rc2;
+	return rc;
+}
+
+/**
+ * avc_has_perm_noaudit - Check permissions but perform no auditing.
+ * @state: SELinux state
+ * @ssid: source security identifier
+ * @tsid: target security identifier
+ * @tclass: target security class
+ * @requested: requested permissions, interpreted based on @tclass
+ * @flags:  AVC_STRICT or 0
+ * @avd: access vector decisions
+ *
+ * Check the AVC to determine whether the @requested permissions are granted
+ * for the SID pair (@ssid, @tsid), interpreting the permissions
+ * based on @tclass, and call the security server on a cache miss to obtain
+ * a new decision and add it to the cache.  Return a copy of the decisions
+ * in @avd.  Return %0 if all @requested permissions are granted,
+ * -%EACCES if any permissions are denied, or another -errno upon
+ * other errors.  This function is typically called by avc_has_perm(),
+ * but may also be called directly to separate permission checking from
+ * auditing, e.g. in cases where a lock must be held for the check but
+ * should be released for the auditing.
+ */
+inline int avc_has_perm_noaudit(struct selinux_state *state,
+				u32 ssid, u32 tsid,
+				u16 tclass, u32 requested,
+				unsigned int flags,
+				struct av_decision *avd)
+{
+	struct avc_node *node;
+	struct avc_xperms_node xp_node;
+	int rc = 0;
+	u32 denied;
+
+	if (WARN_ON(!requested))
+		return -EACCES;
+
+	rcu_read_lock();
+
+	node = avc_lookup(state->avc, ssid, tsid, tclass);
+	if (unlikely(!node))
+		avc_compute_av(state, ssid, tsid, tclass, avd, &xp_node);
+	else
+		memcpy(avd, &node->ae.avd, sizeof(*avd));
+
+	denied = requested & ~(avd->allowed);
+	if (unlikely(denied))
+		rc = avc_denied(state, ssid, tsid, tclass, requested, 0, 0,
+				flags, avd);
+
+	rcu_read_unlock();
+	return rc;
+}
+
+/**
+ * avc_has_perm - Check permissions and perform any appropriate auditing.
+ * @state: SELinux state
+ * @ssid: source security identifier
+ * @tsid: target security identifier
+ * @tclass: target security class
+ * @requested: requested permissions, interpreted based on @tclass
+ * @auditdata: auxiliary audit data
+ *
+ * Check the AVC to determine whether the @requested permissions are granted
+ * for the SID pair (@ssid, @tsid), interpreting the permissions
+ * based on @tclass, and call the security server on a cache miss to obtain
+ * a new decision and add it to the cache.  Audit the granting or denial of
+ * permissions in accordance with the policy.  Return %0 if all @requested
+ * permissions are granted, -%EACCES if any permissions are denied, or
+ * another -errno upon other errors.
+ */
+int avc_has_perm(struct selinux_state *state, u32 ssid, u32 tsid, u16 tclass,
+		 u32 requested, struct common_audit_data *auditdata)
+{
+	struct av_decision avd;
+	int rc, rc2;
+
+	rc = avc_has_perm_noaudit(state, ssid, tsid, tclass, requested, 0,
+				  &avd);
+
+	rc2 = avc_audit(state, ssid, tsid, tclass, requested, &avd, rc,
+			auditdata);
+	if (rc2)
+		return rc2;
+	return rc;
+}
+
+u32 avc_policy_seqno(struct selinux_state *state)
+{
+	return state->avc->avc_cache.latest_notif;
+}
+
+void avc_disable(void)
+{
+	/*
+	 * If you are looking at this because you have realized that we are
+	 * not destroying the avc_node_cachep it might be easy to fix, but
+	 * I don't know the memory barrier semantics well enough to know.  It's
+	 * possible that some other task dereferenced security_ops when
+	 * it still pointed to selinux operations.  If that is the case it's
+	 * possible that it is about to use the avc and is about to need the
+	 * avc_node_cachep.  I know I could wrap the security.c security_ops call
+	 * in an rcu_lock, but seriously, it's not worth it.  Instead I just flush
+	 * the cache and get that memory back.
+	 */
+	if (avc_node_cachep) {
+		avc_flush(selinux_state.avc);
+		/* kmem_cache_destroy(avc_node_cachep); */
+	}
+}