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-rw-r--r--security/selinux/avc.c949
1 files changed, 949 insertions, 0 deletions
diff --git a/security/selinux/avc.c b/security/selinux/avc.c
new file mode 100644
index 000000000000..fe6285e5c68f
--- /dev/null
+++ b/security/selinux/avc.c
@@ -0,0 +1,949 @@
+/*
+ * Implementation of the kernel access vector cache (AVC).
+ *
+ * Authors: Stephen Smalley, <sds@epoch.ncsc.mil>
+ * 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>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2,
+ * as published by the Free Software Foundation.
+ */
+#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 <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"
+
+static const struct av_perm_to_string
+{
+ u16 tclass;
+ u32 value;
+ const char *name;
+} av_perm_to_string[] = {
+#define S_(c, v, s) { c, v, s },
+#include "av_perm_to_string.h"
+#undef S_
+};
+
+#ifdef CONFIG_AUDIT
+static const char *class_to_string[] = {
+#define S_(s) s,
+#include "class_to_string.h"
+#undef S_
+};
+#endif
+
+#define TB_(s) static const char * s [] = {
+#define TE_(s) };
+#define S_(s) s,
+#include "common_perm_to_string.h"
+#undef TB_
+#undef TE_
+#undef S_
+
+static const struct av_inherit
+{
+ u16 tclass;
+ const char **common_pts;
+ u32 common_base;
+} av_inherit[] = {
+#define S_(c, i, b) { c, common_##i##_perm_to_string, b },
+#include "av_inherit.h"
+#undef S_
+};
+
+#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) \
+do { \
+ per_cpu(avc_cache_stats, get_cpu()).field++; \
+ put_cpu(); \
+} while (0)
+#else
+#define avc_cache_stats_incr(field) do {} while (0)
+#endif
+
+struct avc_entry {
+ u32 ssid;
+ u32 tsid;
+ u16 tclass;
+ struct av_decision avd;
+ atomic_t used; /* used recently */
+};
+
+struct avc_node {
+ struct avc_entry ae;
+ struct list_head list;
+ struct rcu_head rhead;
+};
+
+struct avc_cache {
+ struct list_head slots[AVC_CACHE_SLOTS];
+ 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 ssid, u32 tsid,
+ u16 tclass, u32 perms,
+ u32 *out_retained);
+ u32 events;
+ u32 ssid;
+ u32 tsid;
+ u16 tclass;
+ u32 perms;
+ struct avc_callback_node *next;
+};
+
+/* Exported via selinufs */
+unsigned int avc_cache_threshold = AVC_DEF_CACHE_THRESHOLD;
+
+#ifdef CONFIG_SECURITY_SELINUX_AVC_STATS
+DEFINE_PER_CPU(struct avc_cache_stats, avc_cache_stats) = { 0 };
+#endif
+
+static struct avc_cache avc_cache;
+static struct avc_callback_node *avc_callbacks;
+static kmem_cache_t *avc_node_cachep;
+
+static inline int avc_hash(u32 ssid, u32 tsid, u16 tclass)
+{
+ return (ssid ^ (tsid<<2) ^ (tclass<<4)) & (AVC_CACHE_SLOTS - 1);
+}
+
+/**
+ * avc_dump_av - Display an access vector in human-readable form.
+ * @tclass: target security class
+ * @av: access vector
+ */
+static void avc_dump_av(struct audit_buffer *ab, u16 tclass, u32 av)
+{
+ const char **common_pts = NULL;
+ u32 common_base = 0;
+ int i, i2, perm;
+
+ if (av == 0) {
+ audit_log_format(ab, " null");
+ return;
+ }
+
+ for (i = 0; i < ARRAY_SIZE(av_inherit); i++) {
+ if (av_inherit[i].tclass == tclass) {
+ common_pts = av_inherit[i].common_pts;
+ common_base = av_inherit[i].common_base;
+ break;
+ }
+ }
+
+ audit_log_format(ab, " {");
+ i = 0;
+ perm = 1;
+ while (perm < common_base) {
+ if (perm & av) {
+ audit_log_format(ab, " %s", common_pts[i]);
+ av &= ~perm;
+ }
+ i++;
+ perm <<= 1;
+ }
+
+ while (i < sizeof(av) * 8) {
+ if (perm & av) {
+ for (i2 = 0; i2 < ARRAY_SIZE(av_perm_to_string); i2++) {
+ if ((av_perm_to_string[i2].tclass == tclass) &&
+ (av_perm_to_string[i2].value == perm))
+ break;
+ }
+ if (i2 < ARRAY_SIZE(av_perm_to_string)) {
+ audit_log_format(ab, " %s",
+ av_perm_to_string[i2].name);
+ av &= ~perm;
+ }
+ }
+ i++;
+ perm <<= 1;
+ }
+
+ if (av)
+ audit_log_format(ab, " 0x%x", av);
+
+ audit_log_format(ab, " }");
+}
+
+/**
+ * avc_dump_query - Display a SID pair and a class in human-readable form.
+ * @ssid: source security identifier
+ * @tsid: target security identifier
+ * @tclass: target security class
+ */
+static void avc_dump_query(struct audit_buffer *ab, u32 ssid, u32 tsid, u16 tclass)
+{
+ int rc;
+ char *scontext;
+ u32 scontext_len;
+
+ rc = security_sid_to_context(ssid, &scontext, &scontext_len);
+ if (rc)
+ audit_log_format(ab, "ssid=%d", ssid);
+ else {
+ audit_log_format(ab, "scontext=%s", scontext);
+ kfree(scontext);
+ }
+
+ rc = security_sid_to_context(tsid, &scontext, &scontext_len);
+ if (rc)
+ audit_log_format(ab, " tsid=%d", tsid);
+ else {
+ audit_log_format(ab, " tcontext=%s", scontext);
+ kfree(scontext);
+ }
+ audit_log_format(ab, " tclass=%s", class_to_string[tclass]);
+}
+
+/**
+ * avc_init - Initialize the AVC.
+ *
+ * Initialize the access vector cache.
+ */
+void __init avc_init(void)
+{
+ int i;
+
+ for (i = 0; i < AVC_CACHE_SLOTS; i++) {
+ INIT_LIST_HEAD(&avc_cache.slots[i]);
+ spin_lock_init(&avc_cache.slots_lock[i]);
+ }
+ atomic_set(&avc_cache.active_nodes, 0);
+ atomic_set(&avc_cache.lru_hint, 0);
+
+ avc_node_cachep = kmem_cache_create("avc_node", sizeof(struct avc_node),
+ 0, SLAB_PANIC, NULL, NULL);
+
+ audit_log(current->audit_context, "AVC INITIALIZED\n");
+}
+
+int avc_get_hash_stats(char *page)
+{
+ int i, chain_len, max_chain_len, slots_used;
+ struct avc_node *node;
+
+ rcu_read_lock();
+
+ slots_used = 0;
+ max_chain_len = 0;
+ for (i = 0; i < AVC_CACHE_SLOTS; i++) {
+ if (!list_empty(&avc_cache.slots[i])) {
+ slots_used++;
+ chain_len = 0;
+ list_for_each_entry_rcu(node, &avc_cache.slots[i], 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_cache.active_nodes),
+ slots_used, AVC_CACHE_SLOTS, max_chain_len);
+}
+
+static void avc_node_free(struct rcu_head *rhead)
+{
+ struct avc_node *node = container_of(rhead, struct avc_node, rhead);
+ kmem_cache_free(avc_node_cachep, node);
+ avc_cache_stats_incr(frees);
+}
+
+static void avc_node_delete(struct avc_node *node)
+{
+ list_del_rcu(&node->list);
+ call_rcu(&node->rhead, avc_node_free);
+ atomic_dec(&avc_cache.active_nodes);
+}
+
+static void avc_node_kill(struct avc_node *node)
+{
+ kmem_cache_free(avc_node_cachep, node);
+ avc_cache_stats_incr(frees);
+ atomic_dec(&avc_cache.active_nodes);
+}
+
+static void avc_node_replace(struct avc_node *new, struct avc_node *old)
+{
+ list_replace_rcu(&old->list, &new->list);
+ call_rcu(&old->rhead, avc_node_free);
+ atomic_dec(&avc_cache.active_nodes);
+}
+
+static inline int avc_reclaim_node(void)
+{
+ struct avc_node *node;
+ int hvalue, try, ecx;
+ unsigned long flags;
+
+ for (try = 0, ecx = 0; try < AVC_CACHE_SLOTS; try++ ) {
+ hvalue = atomic_inc_return(&avc_cache.lru_hint) & (AVC_CACHE_SLOTS - 1);
+
+ if (!spin_trylock_irqsave(&avc_cache.slots_lock[hvalue], flags))
+ continue;
+
+ list_for_each_entry(node, &avc_cache.slots[hvalue], list) {
+ if (atomic_dec_and_test(&node->ae.used)) {
+ /* Recently Unused */
+ avc_node_delete(node);
+ avc_cache_stats_incr(reclaims);
+ ecx++;
+ if (ecx >= AVC_CACHE_RECLAIM) {
+ spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
+ goto out;
+ }
+ }
+ }
+ spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flags);
+ }
+out:
+ return ecx;
+}
+
+static struct avc_node *avc_alloc_node(void)
+{
+ struct avc_node *node;
+
+ node = kmem_cache_alloc(avc_node_cachep, SLAB_ATOMIC);
+ if (!node)
+ goto out;
+
+ memset(node, 0, sizeof(*node));
+ INIT_RCU_HEAD(&node->rhead);
+ INIT_LIST_HEAD(&node->list);
+ atomic_set(&node->ae.used, 1);
+ avc_cache_stats_incr(allocations);
+
+ if (atomic_inc_return(&avc_cache.active_nodes) > avc_cache_threshold)
+ avc_reclaim_node();
+
+out:
+ return node;
+}
+
+static void avc_node_populate(struct avc_node *node, u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
+{
+ node->ae.ssid = ssid;
+ node->ae.tsid = tsid;
+ node->ae.tclass = tclass;
+ memcpy(&node->ae.avd, &ae->avd, sizeof(node->ae.avd));
+}
+
+static inline struct avc_node *avc_search_node(u32 ssid, u32 tsid, u16 tclass)
+{
+ struct avc_node *node, *ret = NULL;
+ int hvalue;
+
+ hvalue = avc_hash(ssid, tsid, tclass);
+ list_for_each_entry_rcu(node, &avc_cache.slots[hvalue], list) {
+ if (ssid == node->ae.ssid &&
+ tclass == node->ae.tclass &&
+ tsid == node->ae.tsid) {
+ ret = node;
+ break;
+ }
+ }
+
+ if (ret == NULL) {
+ /* cache miss */
+ goto out;
+ }
+
+ /* cache hit */
+ if (atomic_read(&ret->ae.used) != 1)
+ atomic_set(&ret->ae.used, 1);
+out:
+ return ret;
+}
+
+/**
+ * avc_lookup - Look up an AVC entry.
+ * @ssid: source security identifier
+ * @tsid: target security identifier
+ * @tclass: target security class
+ * @requested: requested permissions, interpreted based on @tclass
+ *
+ * Look up an AVC entry that is valid for the
+ * @requested permissions between the SID pair
+ * (@ssid, @tsid), interpreting the permissions
+ * based on @tclass. If a valid AVC entry exists,
+ * then this function return the avc_node.
+ * Otherwise, this function returns NULL.
+ */
+static struct avc_node *avc_lookup(u32 ssid, u32 tsid, u16 tclass, u32 requested)
+{
+ struct avc_node *node;
+
+ avc_cache_stats_incr(lookups);
+ node = avc_search_node(ssid, tsid, tclass);
+
+ if (node && ((node->ae.avd.decided & requested) == requested)) {
+ avc_cache_stats_incr(hits);
+ goto out;
+ }
+
+ node = NULL;
+ avc_cache_stats_incr(misses);
+out:
+ return node;
+}
+
+static int avc_latest_notif_update(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_cache.latest_notif) {
+ printk(KERN_WARNING "avc: seqno %d < latest_notif %d\n",
+ seqno, avc_cache.latest_notif);
+ ret = -EAGAIN;
+ }
+ } else {
+ if (seqno > avc_cache.latest_notif)
+ avc_cache.latest_notif = seqno;
+ }
+ spin_unlock_irqrestore(&notif_lock, flag);
+
+ return ret;
+}
+
+/**
+ * avc_insert - Insert an AVC entry.
+ * @ssid: source security identifier
+ * @tsid: target security identifier
+ * @tclass: target security class
+ * @ae: AVC entry
+ *
+ * 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 @ae->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(u32 ssid, u32 tsid, u16 tclass, struct avc_entry *ae)
+{
+ struct avc_node *pos, *node = NULL;
+ int hvalue;
+ unsigned long flag;
+
+ if (avc_latest_notif_update(ae->avd.seqno, 1))
+ goto out;
+
+ node = avc_alloc_node();
+ if (node) {
+ hvalue = avc_hash(ssid, tsid, tclass);
+ avc_node_populate(node, ssid, tsid, tclass, ae);
+
+ spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
+ list_for_each_entry(pos, &avc_cache.slots[hvalue], list) {
+ if (pos->ae.ssid == ssid &&
+ pos->ae.tsid == tsid &&
+ pos->ae.tclass == tclass) {
+ avc_node_replace(node, pos);
+ goto found;
+ }
+ }
+ list_add_rcu(&node->list, &avc_cache.slots[hvalue]);
+found:
+ spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
+ }
+out:
+ return node;
+}
+
+static inline void avc_print_ipv6_addr(struct audit_buffer *ab,
+ struct in6_addr *addr, u16 port,
+ char *name1, char *name2)
+{
+ if (!ipv6_addr_any(addr))
+ audit_log_format(ab, " %s=%04x:%04x:%04x:%04x:%04x:"
+ "%04x:%04x:%04x", name1, NIP6(*addr));
+ if (port)
+ audit_log_format(ab, " %s=%d", name2, ntohs(port));
+}
+
+static inline void avc_print_ipv4_addr(struct audit_buffer *ab, u32 addr,
+ u16 port, char *name1, char *name2)
+{
+ if (addr)
+ audit_log_format(ab, " %s=%d.%d.%d.%d", name1, NIPQUAD(addr));
+ if (port)
+ audit_log_format(ab, " %s=%d", name2, ntohs(port));
+}
+
+/**
+ * avc_audit - Audit the granting or denial of permissions.
+ * @ssid: source security identifier
+ * @tsid: target security identifier
+ * @tclass: target security class
+ * @requested: requested permissions
+ * @avd: access vector decisions
+ * @result: result from avc_has_perm_noaudit
+ * @a: auxiliary audit data
+ *
+ * Audit the granting or denial of permissions in accordance
+ * with the policy. This function is typically called by
+ * avc_has_perm() after a permission check, but can also be
+ * called directly by callers who use avc_has_perm_noaudit()
+ * in order to separate the permission check from the auditing.
+ * For example, this separation is useful when the permission check must
+ * be performed under a lock, to allow the lock to be released
+ * before calling the auditing code.
+ */
+void avc_audit(u32 ssid, u32 tsid,
+ u16 tclass, u32 requested,
+ struct av_decision *avd, int result, struct avc_audit_data *a)
+{
+ struct task_struct *tsk = current;
+ struct inode *inode = NULL;
+ u32 denied, audited;
+ struct audit_buffer *ab;
+
+ denied = requested & ~avd->allowed;
+ if (denied) {
+ audited = denied;
+ if (!(audited & avd->auditdeny))
+ return;
+ } else if (result) {
+ audited = denied = requested;
+ } else {
+ audited = requested;
+ if (!(audited & avd->auditallow))
+ return;
+ }
+
+ ab = audit_log_start(current->audit_context);
+ if (!ab)
+ return; /* audit_panic has been called */
+ audit_log_format(ab, "avc: %s ", denied ? "denied" : "granted");
+ avc_dump_av(ab, tclass,audited);
+ audit_log_format(ab, " for ");
+ if (a && a->tsk)
+ tsk = a->tsk;
+ if (tsk && tsk->pid) {
+ struct mm_struct *mm;
+ struct vm_area_struct *vma;
+ audit_log_format(ab, " pid=%d", tsk->pid);
+ if (tsk == current)
+ mm = current->mm;
+ else
+ mm = get_task_mm(tsk);
+ if (mm) {
+ if (down_read_trylock(&mm->mmap_sem)) {
+ vma = mm->mmap;
+ while (vma) {
+ if ((vma->vm_flags & VM_EXECUTABLE) &&
+ vma->vm_file) {
+ audit_log_d_path(ab, "exe=",
+ vma->vm_file->f_dentry,
+ vma->vm_file->f_vfsmnt);
+ break;
+ }
+ vma = vma->vm_next;
+ }
+ up_read(&mm->mmap_sem);
+ } else {
+ audit_log_format(ab, " comm=%s", tsk->comm);
+ }
+ if (tsk != current)
+ mmput(mm);
+ } else {
+ audit_log_format(ab, " comm=%s", tsk->comm);
+ }
+ }
+ if (a) {
+ switch (a->type) {
+ case AVC_AUDIT_DATA_IPC:
+ audit_log_format(ab, " key=%d", a->u.ipc_id);
+ break;
+ case AVC_AUDIT_DATA_CAP:
+ audit_log_format(ab, " capability=%d", a->u.cap);
+ break;
+ case AVC_AUDIT_DATA_FS:
+ if (a->u.fs.dentry) {
+ struct dentry *dentry = a->u.fs.dentry;
+ if (a->u.fs.mnt) {
+ audit_log_d_path(ab, "path=", dentry,
+ a->u.fs.mnt);
+ } else {
+ audit_log_format(ab, " name=%s",
+ dentry->d_name.name);
+ }
+ inode = dentry->d_inode;
+ } else if (a->u.fs.inode) {
+ struct dentry *dentry;
+ inode = a->u.fs.inode;
+ dentry = d_find_alias(inode);
+ if (dentry) {
+ audit_log_format(ab, " name=%s",
+ dentry->d_name.name);
+ dput(dentry);
+ }
+ }
+ if (inode)
+ audit_log_format(ab, " dev=%s ino=%ld",
+ inode->i_sb->s_id,
+ inode->i_ino);
+ break;
+ case AVC_AUDIT_DATA_NET:
+ if (a->u.net.sk) {
+ struct sock *sk = a->u.net.sk;
+ struct unix_sock *u;
+ int len = 0;
+ char *p = NULL;
+
+ switch (sk->sk_family) {
+ case AF_INET: {
+ struct inet_sock *inet = inet_sk(sk);
+
+ avc_print_ipv4_addr(ab, inet->rcv_saddr,
+ inet->sport,
+ "laddr", "lport");
+ avc_print_ipv4_addr(ab, inet->daddr,
+ inet->dport,
+ "faddr", "fport");
+ break;
+ }
+ case AF_INET6: {
+ struct inet_sock *inet = inet_sk(sk);
+ struct ipv6_pinfo *inet6 = inet6_sk(sk);
+
+ avc_print_ipv6_addr(ab, &inet6->rcv_saddr,
+ inet->sport,
+ "laddr", "lport");
+ avc_print_ipv6_addr(ab, &inet6->daddr,
+ inet->dport,
+ "faddr", "fport");
+ break;
+ }
+ case AF_UNIX:
+ u = unix_sk(sk);
+ if (u->dentry) {
+ audit_log_d_path(ab, "path=",
+ u->dentry, u->mnt);
+ break;
+ }
+ if (!u->addr)
+ break;
+ len = u->addr->len-sizeof(short);
+ p = &u->addr->name->sun_path[0];
+ if (*p)
+ audit_log_format(ab,
+ "path=%*.*s", len,
+ len, p);
+ else
+ audit_log_format(ab,
+ "path=@%*.*s", len-1,
+ len-1, p+1);
+ break;
+ }
+ }
+
+ switch (a->u.net.family) {
+ case AF_INET:
+ avc_print_ipv4_addr(ab, a->u.net.v4info.saddr,
+ a->u.net.sport,
+ "saddr", "src");
+ avc_print_ipv4_addr(ab, a->u.net.v4info.daddr,
+ a->u.net.dport,
+ "daddr", "dest");
+ break;
+ case AF_INET6:
+ avc_print_ipv6_addr(ab, &a->u.net.v6info.saddr,
+ a->u.net.sport,
+ "saddr", "src");
+ avc_print_ipv6_addr(ab, &a->u.net.v6info.daddr,
+ a->u.net.dport,
+ "daddr", "dest");
+ break;
+ }
+ if (a->u.net.netif)
+ audit_log_format(ab, " netif=%s",
+ a->u.net.netif);
+ break;
+ }
+ }
+ audit_log_format(ab, " ");
+ avc_dump_query(ab, ssid, tsid, tclass);
+ audit_log_end(ab);
+}
+
+/**
+ * avc_add_callback - Register a callback for security events.
+ * @callback: callback function
+ * @events: security events
+ * @ssid: source security identifier or %SECSID_WILD
+ * @tsid: target security identifier or %SECSID_WILD
+ * @tclass: target security class
+ * @perms: permissions
+ *
+ * Register a callback function for events in the set @events
+ * related to the SID pair (@ssid, @tsid) and
+ * and the permissions @perms, interpreting
+ * @perms based on @tclass. Returns %0 on success or
+ * -%ENOMEM if insufficient memory exists to add the callback.
+ */
+int avc_add_callback(int (*callback)(u32 event, u32 ssid, u32 tsid,
+ u16 tclass, u32 perms,
+ u32 *out_retained),
+ u32 events, u32 ssid, u32 tsid,
+ u16 tclass, u32 perms)
+{
+ struct avc_callback_node *c;
+ int rc = 0;
+
+ c = kmalloc(sizeof(*c), GFP_ATOMIC);
+ if (!c) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ c->callback = callback;
+ c->events = events;
+ c->ssid = ssid;
+ c->tsid = tsid;
+ c->perms = perms;
+ c->next = avc_callbacks;
+ avc_callbacks = c;
+out:
+ return rc;
+}
+
+static inline int avc_sidcmp(u32 x, u32 y)
+{
+ return (x == y || x == SECSID_WILD || y == SECSID_WILD);
+}
+
+/**
+ * avc_update_node Update an AVC entry
+ * @event : Updating event
+ * @perms : Permission mask bits
+ * @ssid,@tsid,@tclass : identifier of an AVC entry
+ *
+ * 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 update the AVC entry. The original AVC-entry object
+ * will release later by RCU.
+ */
+static int avc_update_node(u32 event, u32 perms, u32 ssid, u32 tsid, u16 tclass)
+{
+ int hvalue, rc = 0;
+ unsigned long flag;
+ struct avc_node *pos, *node, *orig = NULL;
+
+ node = avc_alloc_node();
+ if (!node) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ /* Lock the target slot */
+ hvalue = avc_hash(ssid, tsid, tclass);
+ spin_lock_irqsave(&avc_cache.slots_lock[hvalue], flag);
+
+ list_for_each_entry(pos, &avc_cache.slots[hvalue], list){
+ if ( ssid==pos->ae.ssid &&
+ tsid==pos->ae.tsid &&
+ tclass==pos->ae.tclass ){
+ orig = pos;
+ break;
+ }
+ }
+
+ if (!orig) {
+ rc = -ENOENT;
+ avc_node_kill(node);
+ goto out_unlock;
+ }
+
+ /*
+ * Copy and replace original node.
+ */
+
+ avc_node_populate(node, ssid, tsid, tclass, &orig->ae);
+
+ switch (event) {
+ case AVC_CALLBACK_GRANT:
+ node->ae.avd.allowed |= perms;
+ 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;
+ }
+ avc_node_replace(node, orig);
+out_unlock:
+ spin_unlock_irqrestore(&avc_cache.slots_lock[hvalue], flag);
+out:
+ return rc;
+}
+
+/**
+ * avc_ss_reset - Flush the cache and revalidate migrated permissions.
+ * @seqno: policy sequence number
+ */
+int avc_ss_reset(u32 seqno)
+{
+ struct avc_callback_node *c;
+ int i, rc = 0;
+ unsigned long flag;
+ struct avc_node *node;
+
+ for (i = 0; i < AVC_CACHE_SLOTS; i++) {
+ spin_lock_irqsave(&avc_cache.slots_lock[i], flag);
+ list_for_each_entry(node, &avc_cache.slots[i], list)
+ avc_node_delete(node);
+ spin_unlock_irqrestore(&avc_cache.slots_lock[i], flag);
+ }
+
+ for (c = avc_callbacks; c; c = c->next) {
+ if (c->events & AVC_CALLBACK_RESET) {
+ rc = c->callback(AVC_CALLBACK_RESET,
+ 0, 0, 0, 0, NULL);
+ if (rc)
+ goto out;
+ }
+ }
+
+ avc_latest_notif_update(seqno, 0);
+out:
+ return rc;
+}
+
+/**
+ * avc_has_perm_noaudit - Check permissions but perform no auditing.
+ * @ssid: source security identifier
+ * @tsid: target security identifier
+ * @tclass: target security class
+ * @requested: requested permissions, interpreted based on @tclass
+ * @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.
+ */
+int avc_has_perm_noaudit(u32 ssid, u32 tsid,
+ u16 tclass, u32 requested,
+ struct av_decision *avd)
+{
+ struct avc_node *node;
+ struct avc_entry entry, *p_ae;
+ int rc = 0;
+ u32 denied;
+
+ rcu_read_lock();
+
+ node = avc_lookup(ssid, tsid, tclass, requested);
+ if (!node) {
+ rcu_read_unlock();
+ rc = security_compute_av(ssid,tsid,tclass,requested,&entry.avd);
+ if (rc)
+ goto out;
+ rcu_read_lock();
+ node = avc_insert(ssid,tsid,tclass,&entry);
+ }
+
+ p_ae = node ? &node->ae : &entry;
+
+ if (avd)
+ memcpy(avd, &p_ae->avd, sizeof(*avd));
+
+ denied = requested & ~(p_ae->avd.allowed);
+
+ if (!requested || denied) {
+ if (selinux_enforcing)
+ rc = -EACCES;
+ else
+ if (node)
+ avc_update_node(AVC_CALLBACK_GRANT,requested,
+ ssid,tsid,tclass);
+ }
+
+ rcu_read_unlock();
+out:
+ return rc;
+}
+
+/**
+ * avc_has_perm - Check permissions and perform any appropriate auditing.
+ * @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(u32 ssid, u32 tsid, u16 tclass,
+ u32 requested, struct avc_audit_data *auditdata)
+{
+ struct av_decision avd;
+ int rc;
+
+ rc = avc_has_perm_noaudit(ssid, tsid, tclass, requested, &avd);
+ avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
+ return rc;
+}