Linux 2.6.17.7

[linux/fpc-iii.git] / kernel / auditfilter.c

/* auditfilter.c -- filtering of audit events
 *
 * Copyright 2003-2004 Red Hat, Inc.
 * Copyright 2005 Hewlett-Packard Development Company, L.P.
 * Copyright 2005 IBM Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/kernel.h>
#include <linux/audit.h>
#include <linux/kthread.h>
#include <linux/netlink.h>
#include <linux/selinux.h>
#include "audit.h"

/* There are three lists of rules -- one to search at task creation
 * time, one to search at syscall entry time, and another to search at
 * syscall exit time. */
struct list_head audit_filter_list[AUDIT_NR_FILTERS] = {
        LIST_HEAD_INIT(audit_filter_list[0]),
        LIST_HEAD_INIT(audit_filter_list[1]),
        LIST_HEAD_INIT(audit_filter_list[2]),
        LIST_HEAD_INIT(audit_filter_list[3]),
        LIST_HEAD_INIT(audit_filter_list[4]),
        LIST_HEAD_INIT(audit_filter_list[5]),
#if AUDIT_NR_FILTERS != 6
#error Fix audit_filter_list initialiser
#endif
};

static inline void audit_free_rule(struct audit_entry *e)
{
        int i;
        if (e->rule.fields)
                for (i = 0; i < e->rule.field_count; i++) {
                        struct audit_field *f = &e->rule.fields[i];
                        kfree(f->se_str);
                        selinux_audit_rule_free(f->se_rule);
                }
        kfree(e->rule.fields);
        kfree(e);
}

static inline void audit_free_rule_rcu(struct rcu_head *head)
{
        struct audit_entry *e = container_of(head, struct audit_entry, rcu);
        audit_free_rule(e);
}

/* Initialize an audit filterlist entry. */
static inline struct audit_entry *audit_init_entry(u32 field_count)
{
        struct audit_entry *entry;
        struct audit_field *fields;

        entry = kzalloc(sizeof(*entry), GFP_KERNEL);
        if (unlikely(!entry))
                return NULL;

        fields = kzalloc(sizeof(*fields) * field_count, GFP_KERNEL);
        if (unlikely(!fields)) {
                kfree(entry);
                return NULL;
        }
        entry->rule.fields = fields;

        return entry;
}

/* Unpack a filter field's string representation from user-space
 * buffer. */
static char *audit_unpack_string(void **bufp, size_t *remain, size_t len)
{
        char *str;

        if (!*bufp || (len == 0) || (len > *remain))
                return ERR_PTR(-EINVAL);

        /* Of the currently implemented string fields, PATH_MAX
         * defines the longest valid length.
         */
        if (len > PATH_MAX)
                return ERR_PTR(-ENAMETOOLONG);

        str = kmalloc(len + 1, GFP_KERNEL);
        if (unlikely(!str))
                return ERR_PTR(-ENOMEM);

        memcpy(str, *bufp, len);
        str[len] = 0;
        *bufp += len;
        *remain -= len;

        return str;
}

/* Common user-space to kernel rule translation. */
static inline struct audit_entry *audit_to_entry_common(struct audit_rule *rule)
{
        unsigned listnr;
        struct audit_entry *entry;
        int i, err;

        err = -EINVAL;
        listnr = rule->flags & ~AUDIT_FILTER_PREPEND;
        switch(listnr) {
        default:
                goto exit_err;
        case AUDIT_FILTER_USER:
        case AUDIT_FILTER_TYPE:
#ifdef CONFIG_AUDITSYSCALL
        case AUDIT_FILTER_ENTRY:
        case AUDIT_FILTER_EXIT:
        case AUDIT_FILTER_TASK:
#endif
                ;
        }
        if (rule->action != AUDIT_NEVER && rule->action != AUDIT_POSSIBLE &&
            rule->action != AUDIT_ALWAYS)
                goto exit_err;
        if (rule->field_count > AUDIT_MAX_FIELDS)
                goto exit_err;

        err = -ENOMEM;
        entry = audit_init_entry(rule->field_count);
        if (!entry)
                goto exit_err;

        entry->rule.flags = rule->flags & AUDIT_FILTER_PREPEND;
        entry->rule.listnr = listnr;
        entry->rule.action = rule->action;
        entry->rule.field_count = rule->field_count;

        for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
                entry->rule.mask[i] = rule->mask[i];

        return entry;

exit_err:
        return ERR_PTR(err);
}

/* Translate struct audit_rule to kernel's rule respresentation.
 * Exists for backward compatibility with userspace. */
static struct audit_entry *audit_rule_to_entry(struct audit_rule *rule)
{
        struct audit_entry *entry;
        int err = 0;
        int i;

        entry = audit_to_entry_common(rule);
        if (IS_ERR(entry))
                goto exit_nofree;

        for (i = 0; i < rule->field_count; i++) {
                struct audit_field *f = &entry->rule.fields[i];

                f->op = rule->fields[i] & (AUDIT_NEGATE|AUDIT_OPERATORS);
                f->type = rule->fields[i] & ~(AUDIT_NEGATE|AUDIT_OPERATORS);
                f->val = rule->values[i];

                if (f->type & AUDIT_UNUSED_BITS ||
                    f->type == AUDIT_SE_USER ||
                    f->type == AUDIT_SE_ROLE ||
                    f->type == AUDIT_SE_TYPE ||
                    f->type == AUDIT_SE_SEN ||
                    f->type == AUDIT_SE_CLR) {
                        err = -EINVAL;
                        goto exit_free;
                }

                entry->rule.vers_ops = (f->op & AUDIT_OPERATORS) ? 2 : 1;

                /* Support for legacy operators where
                 * AUDIT_NEGATE bit signifies != and otherwise assumes == */
                if (f->op & AUDIT_NEGATE)
                        f->op = AUDIT_NOT_EQUAL;
                else if (!f->op)
                        f->op = AUDIT_EQUAL;
                else if (f->op == AUDIT_OPERATORS) {
                        err = -EINVAL;
                        goto exit_free;
                }
        }

exit_nofree:
        return entry;

exit_free:
        audit_free_rule(entry);
        return ERR_PTR(err);
}

/* Translate struct audit_rule_data to kernel's rule respresentation. */
static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data,
                                               size_t datasz)
{
        int err = 0;
        struct audit_entry *entry;
        void *bufp;
        size_t remain = datasz - sizeof(struct audit_rule_data);
        int i;
        char *str;

        entry = audit_to_entry_common((struct audit_rule *)data);
        if (IS_ERR(entry))
                goto exit_nofree;

        bufp = data->buf;
        entry->rule.vers_ops = 2;
        for (i = 0; i < data->field_count; i++) {
                struct audit_field *f = &entry->rule.fields[i];

                err = -EINVAL;
                if (!(data->fieldflags[i] & AUDIT_OPERATORS) ||
                    data->fieldflags[i] & ~AUDIT_OPERATORS)
                        goto exit_free;

                f->op = data->fieldflags[i] & AUDIT_OPERATORS;
                f->type = data->fields[i];
                f->val = data->values[i];
                f->se_str = NULL;
                f->se_rule = NULL;
                switch(f->type) {
                case AUDIT_SE_USER:
                case AUDIT_SE_ROLE:
                case AUDIT_SE_TYPE:
                case AUDIT_SE_SEN:
                case AUDIT_SE_CLR:
                        str = audit_unpack_string(&bufp, &remain, f->val);
                        if (IS_ERR(str))
                                goto exit_free;
                        entry->rule.buflen += f->val;

                        err = selinux_audit_rule_init(f->type, f->op, str,
                                                      &f->se_rule);
                        /* Keep currently invalid fields around in case they
                         * become valid after a policy reload. */
                        if (err == -EINVAL) {
                                printk(KERN_WARNING "audit rule for selinux "
                                       "\'%s\' is invalid\n",  str);
                                err = 0;
                        }
                        if (err) {
                                kfree(str);
                                goto exit_free;
                        } else
                                f->se_str = str;
                        break;
                }
        }

exit_nofree:
        return entry;

exit_free:
        audit_free_rule(entry);
        return ERR_PTR(err);
}

/* Pack a filter field's string representation into data block. */
static inline size_t audit_pack_string(void **bufp, char *str)
{
        size_t len = strlen(str);

        memcpy(*bufp, str, len);
        *bufp += len;

        return len;
}

/* Translate kernel rule respresentation to struct audit_rule.
 * Exists for backward compatibility with userspace. */
static struct audit_rule *audit_krule_to_rule(struct audit_krule *krule)
{
        struct audit_rule *rule;
        int i;

        rule = kmalloc(sizeof(*rule), GFP_KERNEL);
        if (unlikely(!rule))
                return ERR_PTR(-ENOMEM);
        memset(rule, 0, sizeof(*rule));

        rule->flags = krule->flags | krule->listnr;
        rule->action = krule->action;
        rule->field_count = krule->field_count;
        for (i = 0; i < rule->field_count; i++) {
                rule->values[i] = krule->fields[i].val;
                rule->fields[i] = krule->fields[i].type;

                if (krule->vers_ops == 1) {
                        if (krule->fields[i].op & AUDIT_NOT_EQUAL)
                                rule->fields[i] |= AUDIT_NEGATE;
                } else {
                        rule->fields[i] |= krule->fields[i].op;
                }
        }
        for (i = 0; i < AUDIT_BITMASK_SIZE; i++) rule->mask[i] = krule->mask[i];

        return rule;
}

/* Translate kernel rule respresentation to struct audit_rule_data. */
static struct audit_rule_data *audit_krule_to_data(struct audit_krule *krule)
{
        struct audit_rule_data *data;
        void *bufp;
        int i;

        data = kmalloc(sizeof(*data) + krule->buflen, GFP_KERNEL);
        if (unlikely(!data))
                return ERR_PTR(-ENOMEM);
        memset(data, 0, sizeof(*data));

        data->flags = krule->flags | krule->listnr;
        data->action = krule->action;
        data->field_count = krule->field_count;
        bufp = data->buf;
        for (i = 0; i < data->field_count; i++) {
                struct audit_field *f = &krule->fields[i];

                data->fields[i] = f->type;
                data->fieldflags[i] = f->op;
                switch(f->type) {
                case AUDIT_SE_USER:
                case AUDIT_SE_ROLE:
                case AUDIT_SE_TYPE:
                case AUDIT_SE_SEN:
                case AUDIT_SE_CLR:
                        data->buflen += data->values[i] =
                                audit_pack_string(&bufp, f->se_str);
                        break;
                default:
                        data->values[i] = f->val;
                }
        }
        for (i = 0; i < AUDIT_BITMASK_SIZE; i++) data->mask[i] = krule->mask[i];

        return data;
}

/* Compare two rules in kernel format.  Considered success if rules
 * don't match. */
static int audit_compare_rule(struct audit_krule *a, struct audit_krule *b)
{
        int i;

        if (a->flags != b->flags ||
            a->listnr != b->listnr ||
            a->action != b->action ||
            a->field_count != b->field_count)
                return 1;

        for (i = 0; i < a->field_count; i++) {
                if (a->fields[i].type != b->fields[i].type ||
                    a->fields[i].op != b->fields[i].op)
                        return 1;

                switch(a->fields[i].type) {
                case AUDIT_SE_USER:
                case AUDIT_SE_ROLE:
                case AUDIT_SE_TYPE:
                case AUDIT_SE_SEN:
                case AUDIT_SE_CLR:
                        if (strcmp(a->fields[i].se_str, b->fields[i].se_str))
                                return 1;
                        break;
                default:
                        if (a->fields[i].val != b->fields[i].val)
                                return 1;
                }
        }

        for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
                if (a->mask[i] != b->mask[i])
                        return 1;

        return 0;
}

/* Duplicate selinux field information.  The se_rule is opaque, so must be
 * re-initialized. */
static inline int audit_dupe_selinux_field(struct audit_field *df,
                                           struct audit_field *sf)
{
        int ret = 0;
        char *se_str;

        /* our own copy of se_str */
        se_str = kstrdup(sf->se_str, GFP_KERNEL);
        if (unlikely(IS_ERR(se_str)))
            return -ENOMEM;
        df->se_str = se_str;

        /* our own (refreshed) copy of se_rule */
        ret = selinux_audit_rule_init(df->type, df->op, df->se_str,
                                      &df->se_rule);
        /* Keep currently invalid fields around in case they
         * become valid after a policy reload. */
        if (ret == -EINVAL) {
                printk(KERN_WARNING "audit rule for selinux \'%s\' is "
                       "invalid\n", df->se_str);
                ret = 0;
        }

        return ret;
}

/* Duplicate an audit rule.  This will be a deep copy with the exception
 * of the watch - that pointer is carried over.  The selinux specific fields
 * will be updated in the copy.  The point is to be able to replace the old
 * rule with the new rule in the filterlist, then free the old rule. */
static struct audit_entry *audit_dupe_rule(struct audit_krule *old)
{
        u32 fcount = old->field_count;
        struct audit_entry *entry;
        struct audit_krule *new;
        int i, err = 0;

        entry = audit_init_entry(fcount);
        if (unlikely(!entry))
                return ERR_PTR(-ENOMEM);

        new = &entry->rule;
        new->vers_ops = old->vers_ops;
        new->flags = old->flags;
        new->listnr = old->listnr;
        new->action = old->action;
        for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
                new->mask[i] = old->mask[i];
        new->buflen = old->buflen;
        new->field_count = old->field_count;
        memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount);

        /* deep copy this information, updating the se_rule fields, because
         * the originals will all be freed when the old rule is freed. */
        for (i = 0; i < fcount; i++) {
                switch (new->fields[i].type) {
                case AUDIT_SE_USER:
                case AUDIT_SE_ROLE:
                case AUDIT_SE_TYPE:
                case AUDIT_SE_SEN:
                case AUDIT_SE_CLR:
                        err = audit_dupe_selinux_field(&new->fields[i],
                                                       &old->fields[i]);
                }
                if (err) {
                        audit_free_rule(entry);
                        return ERR_PTR(err);
                }
        }

        return entry;
}

/* Add rule to given filterlist if not a duplicate.  Protected by
 * audit_netlink_mutex. */
static inline int audit_add_rule(struct audit_entry *entry,
                                  struct list_head *list)
{
        struct audit_entry *e;

        /* Do not use the _rcu iterator here, since this is the only
         * addition routine. */
        list_for_each_entry(e, list, list) {
                if (!audit_compare_rule(&entry->rule, &e->rule))
                        return -EEXIST;
        }

        if (entry->rule.flags & AUDIT_FILTER_PREPEND) {
                list_add_rcu(&entry->list, list);
        } else {
                list_add_tail_rcu(&entry->list, list);
        }

        return 0;
}

/* Remove an existing rule from filterlist.  Protected by
 * audit_netlink_mutex. */
static inline int audit_del_rule(struct audit_entry *entry,
                                 struct list_head *list)
{
        struct audit_entry  *e;

        /* Do not use the _rcu iterator here, since this is the only
         * deletion routine. */
        list_for_each_entry(e, list, list) {
                if (!audit_compare_rule(&entry->rule, &e->rule)) {
                        list_del_rcu(&e->list);
                        call_rcu(&e->rcu, audit_free_rule_rcu);
                        return 0;
                }
        }
        return -ENOENT;         /* No matching rule */
}

/* List rules using struct audit_rule.  Exists for backward
 * compatibility with userspace. */
static int audit_list(void *_dest)
{
        int pid, seq;
        int *dest = _dest;
        struct audit_entry *entry;
        int i;

        pid = dest[0];
        seq = dest[1];
        kfree(dest);

        mutex_lock(&audit_netlink_mutex);

        /* The *_rcu iterators not needed here because we are
           always called with audit_netlink_mutex held. */
        for (i=0; i<AUDIT_NR_FILTERS; i++) {
                list_for_each_entry(entry, &audit_filter_list[i], list) {
                        struct audit_rule *rule;

                        rule = audit_krule_to_rule(&entry->rule);
                        if (unlikely(!rule))
                                break;
                        audit_send_reply(pid, seq, AUDIT_LIST, 0, 1,
                                         rule, sizeof(*rule));
                        kfree(rule);
                }
        }
        audit_send_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
        
        mutex_unlock(&audit_netlink_mutex);
        return 0;
}

/* List rules using struct audit_rule_data. */
static int audit_list_rules(void *_dest)
{
        int pid, seq;
        int *dest = _dest;
        struct audit_entry *e;
        int i;

        pid = dest[0];
        seq = dest[1];
        kfree(dest);

        mutex_lock(&audit_netlink_mutex);

        /* The *_rcu iterators not needed here because we are
           always called with audit_netlink_mutex held. */
        for (i=0; i<AUDIT_NR_FILTERS; i++) {
                list_for_each_entry(e, &audit_filter_list[i], list) {
                        struct audit_rule_data *data;

                        data = audit_krule_to_data(&e->rule);
                        if (unlikely(!data))
                                break;
                        audit_send_reply(pid, seq, AUDIT_LIST_RULES, 0, 1,
                                         data, sizeof(*data));
                        kfree(data);
                }
        }
        audit_send_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0);

        mutex_unlock(&audit_netlink_mutex);
        return 0;
}

/**
 * audit_receive_filter - apply all rules to the specified message type
 * @type: audit message type
 * @pid: target pid for netlink audit messages
 * @uid: target uid for netlink audit messages
 * @seq: netlink audit message sequence (serial) number
 * @data: payload data
 * @datasz: size of payload data
 * @loginuid: loginuid of sender
 * @sid: SE Linux Security ID of sender
 */
int audit_receive_filter(int type, int pid, int uid, int seq, void *data,
                         size_t datasz, uid_t loginuid, u32 sid)
{
        struct task_struct *tsk;
        int *dest;
        int err = 0;
        struct audit_entry *entry;

        switch (type) {
        case AUDIT_LIST:
        case AUDIT_LIST_RULES:
                /* We can't just spew out the rules here because we might fill
                 * the available socket buffer space and deadlock waiting for
                 * auditctl to read from it... which isn't ever going to
                 * happen if we're actually running in the context of auditctl
                 * trying to _send_ the stuff */
                 
                dest = kmalloc(2 * sizeof(int), GFP_KERNEL);
                if (!dest)
                        return -ENOMEM;
                dest[0] = pid;
                dest[1] = seq;

                if (type == AUDIT_LIST)
                        tsk = kthread_run(audit_list, dest, "audit_list");
                else
                        tsk = kthread_run(audit_list_rules, dest,
                                          "audit_list_rules");
                if (IS_ERR(tsk)) {
                        kfree(dest);
                        err = PTR_ERR(tsk);
                }
                break;
        case AUDIT_ADD:
        case AUDIT_ADD_RULE:
                if (type == AUDIT_ADD)
                        entry = audit_rule_to_entry(data);
                else
                        entry = audit_data_to_entry(data, datasz);
                if (IS_ERR(entry))
                        return PTR_ERR(entry);

                err = audit_add_rule(entry,
                                     &audit_filter_list[entry->rule.listnr]);
                if (sid) {
                        char *ctx = NULL;
                        u32 len;
                        if (selinux_ctxid_to_string(sid, &ctx, &len)) {
                                /* Maybe call audit_panic? */
                                audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
                                 "auid=%u ssid=%u add rule to list=%d res=%d",
                                 loginuid, sid, entry->rule.listnr, !err);
                        } else
                                audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
                                 "auid=%u subj=%s add rule to list=%d res=%d",
                                 loginuid, ctx, entry->rule.listnr, !err);
                        kfree(ctx);
                } else
                        audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
                                "auid=%u add rule to list=%d res=%d",
                                loginuid, entry->rule.listnr, !err);

                if (err)
                        audit_free_rule(entry);
                break;
        case AUDIT_DEL:
        case AUDIT_DEL_RULE:
                if (type == AUDIT_DEL)
                        entry = audit_rule_to_entry(data);
                else
                        entry = audit_data_to_entry(data, datasz);
                if (IS_ERR(entry))
                        return PTR_ERR(entry);

                err = audit_del_rule(entry,
                                     &audit_filter_list[entry->rule.listnr]);

                if (sid) {
                        char *ctx = NULL;
                        u32 len;
                        if (selinux_ctxid_to_string(sid, &ctx, &len)) {
                                /* Maybe call audit_panic? */
                                audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
                                        "auid=%u ssid=%u remove rule from list=%d res=%d",
                                         loginuid, sid, entry->rule.listnr, !err);
                        } else
                                audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
                                        "auid=%u subj=%s remove rule from list=%d res=%d",
                                         loginuid, ctx, entry->rule.listnr, !err);
                        kfree(ctx);
                } else
                        audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
                                "auid=%u remove rule from list=%d res=%d",
                                loginuid, entry->rule.listnr, !err);

                audit_free_rule(entry);
                break;
        default:
                return -EINVAL;
        }

        return err;
}

int audit_comparator(const u32 left, const u32 op, const u32 right)
{
        switch (op) {
        case AUDIT_EQUAL:
                return (left == right);
        case AUDIT_NOT_EQUAL:
                return (left != right);
        case AUDIT_LESS_THAN:
                return (left < right);
        case AUDIT_LESS_THAN_OR_EQUAL:
                return (left <= right);
        case AUDIT_GREATER_THAN:
                return (left > right);
        case AUDIT_GREATER_THAN_OR_EQUAL:
                return (left >= right);
        }
        BUG();
        return 0;
}



static int audit_filter_user_rules(struct netlink_skb_parms *cb,
                                   struct audit_krule *rule,
                                   enum audit_state *state)
{
        int i;

        for (i = 0; i < rule->field_count; i++) {
                struct audit_field *f = &rule->fields[i];
                int result = 0;

                switch (f->type) {
                case AUDIT_PID:
                        result = audit_comparator(cb->creds.pid, f->op, f->val);
                        break;
                case AUDIT_UID:
                        result = audit_comparator(cb->creds.uid, f->op, f->val);
                        break;
                case AUDIT_GID:
                        result = audit_comparator(cb->creds.gid, f->op, f->val);
                        break;
                case AUDIT_LOGINUID:
                        result = audit_comparator(cb->loginuid, f->op, f->val);
                        break;
                }

                if (!result)
                        return 0;
        }
        switch (rule->action) {
        case AUDIT_NEVER:    *state = AUDIT_DISABLED;       break;
        case AUDIT_POSSIBLE: *state = AUDIT_BUILD_CONTEXT;  break;
        case AUDIT_ALWAYS:   *state = AUDIT_RECORD_CONTEXT; break;
        }
        return 1;
}

int audit_filter_user(struct netlink_skb_parms *cb, int type)
{
        struct audit_entry *e;
        enum audit_state   state;
        int ret = 1;

        rcu_read_lock();
        list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
                if (audit_filter_user_rules(cb, &e->rule, &state)) {
                        if (state == AUDIT_DISABLED)
                                ret = 0;
                        break;
                }
        }
        rcu_read_unlock();

        return ret; /* Audit by default */
}

int audit_filter_type(int type)
{
        struct audit_entry *e;
        int result = 0;
        
        rcu_read_lock();
        if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE]))
                goto unlock_and_return;

        list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE],
                                list) {
                int i;
                for (i = 0; i < e->rule.field_count; i++) {
                        struct audit_field *f = &e->rule.fields[i];
                        if (f->type == AUDIT_MSGTYPE) {
                                result = audit_comparator(type, f->op, f->val);
                                if (!result)
                                        break;
                        }
                }
                if (result)
                        goto unlock_and_return;
        }
unlock_and_return:
        rcu_read_unlock();
        return result;
}

/* Check to see if the rule contains any selinux fields.  Returns 1 if there
   are selinux fields specified in the rule, 0 otherwise. */
static inline int audit_rule_has_selinux(struct audit_krule *rule)
{
        int i;

        for (i = 0; i < rule->field_count; i++) {
                struct audit_field *f = &rule->fields[i];
                switch (f->type) {
                case AUDIT_SE_USER:
                case AUDIT_SE_ROLE:
                case AUDIT_SE_TYPE:
                case AUDIT_SE_SEN:
                case AUDIT_SE_CLR:
                        return 1;
                }
        }

        return 0;
}

/* This function will re-initialize the se_rule field of all applicable rules.
 * It will traverse the filter lists serarching for rules that contain selinux
 * specific filter fields.  When such a rule is found, it is copied, the
 * selinux field is re-initialized, and the old rule is replaced with the
 * updated rule. */
int selinux_audit_rule_update(void)
{
        struct audit_entry *entry, *n, *nentry;
        int i, err = 0;

        /* audit_netlink_mutex synchronizes the writers */
        mutex_lock(&audit_netlink_mutex);

        for (i = 0; i < AUDIT_NR_FILTERS; i++) {
                list_for_each_entry_safe(entry, n, &audit_filter_list[i], list) {
                        if (!audit_rule_has_selinux(&entry->rule))
                                continue;

                        nentry = audit_dupe_rule(&entry->rule);
                        if (unlikely(IS_ERR(nentry))) {
                                /* save the first error encountered for the
                                 * return value */
                                if (!err)
                                        err = PTR_ERR(nentry);
                                audit_panic("error updating selinux filters");
                                list_del_rcu(&entry->list);
                        } else {
                                list_replace_rcu(&entry->list, &nentry->list);
                        }
                        call_rcu(&entry->rcu, audit_free_rule_rcu);
                }
        }

        mutex_unlock(&audit_netlink_mutex);

        return err;
}