Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 949 insertions, 0 deletions

diff --git a/security/selinux/avc.c b/security/selinux/avc.c
new file mode 100644
index 00000000000..fe6285e5c68
--- /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;
+}