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avc.c

/*
 * 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 av_perm_to_string[] = {
#define S_(c, v, s) { c, v, s },
#include "av_perm_to_string.h"
#undef S_
};

static const char *class_to_string[] = {
#define S_(s) s,
#include "class_to_string.h"
#undef S_
};

#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 av_inherit[] = {
#define S_(c, i, b) { c, common_##i##_perm_to_string, b },
#include "av_inherit.h"
#undef S_
};

const struct selinux_class_perm selinux_class_perm = {
      av_perm_to_string,
      ARRAY_SIZE(av_perm_to_string),
      class_to_string,
      ARRAY_SIZE(class_to_string),
      av_inherit,
      ARRAY_SIZE(av_inherit)
};

#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 struct kmem_cache *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);
      }

      BUG_ON(tclass >= ARRAY_SIZE(class_to_string) || !class_to_string[tclass]);
      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);

      audit_log(current->audit_context, GFP_KERNEL, AUDIT_KERNEL, "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_zalloc(avc_node_cachep, GFP_ATOMIC);
      if (!node)
            goto out;

      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, __be16 port,
                               char *name1, char *name2)
{
      if (!ipv6_addr_any(addr))
            audit_log_format(ab, " %s=" NIP6_FMT, 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, __be32 addr,
                               __be16 port, char *name1, char *name2)
{
      if (addr)
            audit_log_format(ab, " %s=" NIPQUAD_FMT, 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, GFP_ATOMIC, AUDIT_AVC);
      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) {
            audit_log_format(ab, " pid=%d comm=", tsk->pid);
            audit_log_untrustedstring(ab, 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=");
                              audit_log_untrustedstring(ab, 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=");
                              audit_log_untrustedstring(ab, dentry->d_name.name);
                              dput(dentry);
                        }
                  }
                  if (inode)
                        audit_log_format(ab, " dev=%s ino=%lu",
                                     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];
                              audit_log_format(ab, " path=");
                              if (*p)
                                    audit_log_untrustedstring(ab, p);
                              else
                                    audit_log_hex(ab, p, len);
                              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, tmprc;
      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) {
                  tmprc = c->callback(AVC_CALLBACK_RESET,
                                      0, 0, 0, 0, NULL);
                  /* save the first error encountered for the return
                     value and continue processing the callbacks */
                  if (!rc)
                        rc = tmprc;
            }
      }

      avc_latest_notif_update(seqno, 0);
      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
 * @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.
 */
int avc_has_perm_noaudit(u32 ssid, u32 tsid,
                   u16 tclass, u32 requested,
                   unsigned flags,
                   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 || (flags & AVC_STRICT))
                  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, 0, &avd);
      avc_audit(ssid, tsid, tclass, requested, &avd, rc, auditdata);
      return rc;
}

u32 avc_policy_seqno(void)
{
      return avc_cache.latest_notif;
}

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