/* 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/mutex.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/netlink.h>
#include <linux/sched.h>
#include <linux/inotify.h>
#include <linux/security.h>
#include "audit.h"

/*
 * Locking model:
 *
 * audit_filter_mutex:
 *              Synchronizes writes and blocking reads of audit's filterlist
 *              data.  Rcu is used to traverse the filterlist and access
 *              contents of structs audit_entry, audit_watch and opaque
 *              LSM rules during filtering.  If modified, these structures
 *              must be copied and replace their counterparts in the filterlist.
 *              An audit_parent struct is not accessed during filtering, so may
 *              be written directly provided audit_filter_mutex is held.
 */

/*
 * Reference counting:
 *
 * audit_parent: lifetime is from audit_init_parent() to receipt of an IN_IGNORED
 *      event.  Each audit_watch holds a reference to its associated parent.
 *
 * audit_watch: if added to lists, lifetime is from audit_init_watch() to
 *      audit_remove_watch().  Additionally, an audit_watch may exist
 *      temporarily to assist in searching existing filter data.  Each
 *      audit_krule holds a reference to its associated watch.
 */

struct audit_parent {
        struct list_head        ilist;  /* entry in inotify registration list */
        struct list_head        watches; /* associated watches */
        struct inotify_watch    wdata;  /* inotify watch data */
        unsigned                flags;  /* status flags */
};

/*
 * audit_parent status flags:
 *
 * AUDIT_PARENT_INVALID - set anytime rules/watches are auto-removed due to
 * a filesystem event to ensure we're adding audit watches to a valid parent.
 * Technically not needed for IN_DELETE_SELF or IN_UNMOUNT events, as we cannot
 * receive them while we have nameidata, but must be used for IN_MOVE_SELF which
 * we can receive while holding nameidata.
 */
#define AUDIT_PARENT_INVALID    0x001

/* Audit filter lists, defined in <linux/audit.h> */
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
};

DEFINE_MUTEX(audit_filter_mutex);

/* Inotify events we care about. */
#define AUDIT_IN_WATCH IN_MOVE|IN_CREATE|IN_DELETE|IN_DELETE_SELF|IN_MOVE_SELF

void audit_free_parent(struct inotify_watch *i_watch)
{
        struct audit_parent *parent;

        parent = container_of(i_watch, struct audit_parent, wdata);
        WARN_ON(!list_empty(&parent->watches));
        kfree(parent);
}

static inline void audit_get_watch(struct audit_watch *watch)
{
        atomic_inc(&watch->count);
}

static void audit_put_watch(struct audit_watch *watch)
{
        if (atomic_dec_and_test(&watch->count)) {
                WARN_ON(watch->parent);
                WARN_ON(!list_empty(&watch->rules));
                kfree(watch->path);
                kfree(watch);
        }
}

static void audit_remove_watch(struct audit_watch *watch)
{
        list_del(&watch->wlist);
        put_inotify_watch(&watch->parent->wdata);
        watch->parent = NULL;
        audit_put_watch(watch); /* match initial get */
}

static inline void audit_free_rule(struct audit_entry *e)
{
        int i;

        /* some rules don't have associated watches */
        if (e->rule.watch)
                audit_put_watch(e->rule.watch);
        if (e->rule.fields)
                for (i = 0; i < e->rule.field_count; i++) {
                        struct audit_field *f = &e->rule.fields[i];
                        kfree(f->lsm_str);
                        security_audit_rule_free(f->lsm_rule);
                }
        kfree(e->rule.fields);
        kfree(e->rule.filterkey);
        kfree(e);
}

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 a parent watch entry. */
static struct audit_parent *audit_init_parent(struct nameidata *ndp)
{
        struct audit_parent *parent;
        s32 wd;

        parent = kzalloc(sizeof(*parent), GFP_KERNEL);
        if (unlikely(!parent))
                return ERR_PTR(-ENOMEM);

        INIT_LIST_HEAD(&parent->watches);
        parent->flags = 0;

        inotify_init_watch(&parent->wdata);
        /* grab a ref so inotify watch hangs around until we take audit_filter_mutex */
        get_inotify_watch(&parent->wdata);
        wd = inotify_add_watch(audit_ih, &parent->wdata,
                               ndp->path.dentry->d_inode, AUDIT_IN_WATCH);
        if (wd < 0) {
                audit_free_parent(&parent->wdata);
                return ERR_PTR(wd);
        }

        return parent;
}

/* Initialize a watch entry. */
static struct audit_watch *audit_init_watch(char *path)
{
        struct audit_watch *watch;

        watch = kzalloc(sizeof(*watch), GFP_KERNEL);
        if (unlikely(!watch))
                return ERR_PTR(-ENOMEM);

        INIT_LIST_HEAD(&watch->rules);
        atomic_set(&watch->count, 1);
        watch->path = path;
        watch->dev = (dev_t)-1;
        watch->ino = (unsigned long)-1;

        return watch;
}

/* 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. */
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;
}

/* Translate an inode field to kernel respresentation. */
static inline int audit_to_inode(struct audit_krule *krule,
                                 struct audit_field *f)
{
        if (krule->listnr != AUDIT_FILTER_EXIT ||
            krule->watch || krule->inode_f || krule->tree)
                return -EINVAL;

        krule->inode_f = f;
        return 0;
}

/* Translate a watch string to kernel respresentation. */
static int audit_to_watch(struct audit_krule *krule, char *path, int len,
                          u32 op)
{
        struct audit_watch *watch;

        if (!audit_ih)
                return -EOPNOTSUPP;

        if (path[0] != '/' || path[len-1] == '/' ||
            krule->listnr != AUDIT_FILTER_EXIT ||
            op & ~AUDIT_EQUAL ||
            krule->inode_f || krule->watch || krule->tree)
                return -EINVAL;

        watch = audit_init_watch(path);
        if (IS_ERR(watch))
                return PTR_ERR(watch);

        audit_get_watch(watch);
        krule->watch = watch;

        return 0;
}

static __u32 *classes[AUDIT_SYSCALL_CLASSES];

int __init audit_register_class(int class, unsigned *list)
{
        __u32 *p = kzalloc(AUDIT_BITMASK_SIZE * sizeof(__u32), GFP_KERNEL);
        if (!p)
                return -ENOMEM;
        while (*list != ~0U) {
                unsigned n = *list++;
                if (n >= AUDIT_BITMASK_SIZE * 32 - AUDIT_SYSCALL_CLASSES) {
                        kfree(p);
                        return -EINVAL;
                }
                p[AUDIT_WORD(n)] |= AUDIT_BIT(n);
        }
        if (class >= AUDIT_SYSCALL_CLASSES || classes[class]) {
                kfree(p);
                return -EINVAL;
        }
        classes[class] = p;
        return 0;
}

int audit_match_class(int class, unsigned syscall)
{
        if (unlikely(syscall >= AUDIT_BITMASK_SIZE * 32))
                return 0;
        if (unlikely(class >= AUDIT_SYSCALL_CLASSES || !classes[class]))
                return 0;
        return classes[class][AUDIT_WORD(syscall)] & AUDIT_BIT(syscall);
}

#ifdef CONFIG_AUDITSYSCALL
static inline int audit_match_class_bits(int class, u32 *mask)
{
        int i;

        if (classes[class]) {
                for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
                        if (mask[i] & classes[class][i])
                                return 0;
        }
        return 1;
}

static int audit_match_signal(struct audit_entry *entry)
{
        struct audit_field *arch = entry->rule.arch_f;

        if (!arch) {
                /* When arch is unspecified, we must check both masks on biarch
                 * as syscall number alone is ambiguous. */
                return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
                                               entry->rule.mask) &&
                        audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
                                               entry->rule.mask));
        }

        switch(audit_classify_arch(arch->val)) {
        case 0: /* native */
                return (audit_match_class_bits(AUDIT_CLASS_SIGNAL,
                                               entry->rule.mask));
        case 1: /* 32bit on biarch */
                return (audit_match_class_bits(AUDIT_CLASS_SIGNAL_32,
                                               entry->rule.mask));
        default:
                return 1;
        }
}
#endif

/* 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 (unlikely(rule->action == AUDIT_POSSIBLE)) {
                printk(KERN_ERR "AUDIT_POSSIBLE is deprecated\n");
                goto exit_err;
        }
        if (rule->action != AUDIT_NEVER && 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];

        for (i = 0; i < AUDIT_SYSCALL_CLASSES; i++) {
                int bit = AUDIT_BITMASK_SIZE * 32 - i - 1;
                __u32 *p = &entry->rule.mask[AUDIT_WORD(bit)];
                __u32 *class;

                if (!(*p & AUDIT_BIT(bit)))
                        continue;
                *p &= ~AUDIT_BIT(bit);
                class = classes[i];
                if (class) {
                        int j;
                        for (j = 0; j < AUDIT_BITMASK_SIZE; j++)
                                entry->rule.mask[j] |= class[j];
                }
        }

        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;
        struct audit_field *ino_f;
        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];

                err = -EINVAL;
                switch(f->type) {
                default:
                        goto exit_free;
                case AUDIT_PID:
                case AUDIT_UID:
                case AUDIT_EUID:
                case AUDIT_SUID:
                case AUDIT_FSUID:
                case AUDIT_GID:
                case AUDIT_EGID:
                case AUDIT_SGID:
                case AUDIT_FSGID:
                case AUDIT_LOGINUID:
                case AUDIT_PERS:
                case AUDIT_MSGTYPE:
                case AUDIT_PPID:
                case AUDIT_DEVMAJOR:
                case AUDIT_DEVMINOR:
                case AUDIT_EXIT:
                case AUDIT_SUCCESS:
                        /* bit ops are only useful on syscall args */
                        if (f->op == AUDIT_BIT_MASK ||
                                                f->op == AUDIT_BIT_TEST) {
                                err = -EINVAL;
                                goto exit_free;
                        }
                        break;
                case AUDIT_ARG0:
                case AUDIT_ARG1:
                case AUDIT_ARG2:
                case AUDIT_ARG3:
                        break;
                /* arch is only allowed to be = or != */
                case AUDIT_ARCH:
                        if ((f->op != AUDIT_NOT_EQUAL) && (f->op != AUDIT_EQUAL)
                                        && (f->op != AUDIT_NEGATE) && (f->op)) {
                                err = -EINVAL;
                                goto exit_free;
                        }
                        entry->rule.arch_f = f;
                        break;
                case AUDIT_PERM:
                        if (f->val & ~15)
                                goto exit_free;
                        break;
                case AUDIT_FILETYPE:
                        if ((f->val & ~S_IFMT) > S_IFMT)
                                goto exit_free;
                        break;
                case AUDIT_INODE:
                        err = audit_to_inode(&entry->rule, f);
                        if (err)
                                goto exit_free;
                        break;
                }

                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;
                }
        }

        ino_f = entry->rule.inode_f;
        if (ino_f) {
                switch(ino_f->op) {
                case AUDIT_NOT_EQUAL:
                        entry->rule.inode_f = NULL;
                case AUDIT_EQUAL:
                        break;
                default:
                        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;
        struct audit_field *ino_f;
        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->lsm_str = NULL;
                f->lsm_rule = NULL;
                switch(f->type) {
                case AUDIT_PID:
                case AUDIT_UID:
                case AUDIT_EUID:
                case AUDIT_SUID:
                case AUDIT_FSUID:
                case AUDIT_GID:
                case AUDIT_EGID:
                case AUDIT_SGID:
                case AUDIT_FSGID:
                case AUDIT_LOGINUID:
                case AUDIT_PERS:
                case AUDIT_MSGTYPE:
                case AUDIT_PPID:
                case AUDIT_DEVMAJOR:
                case AUDIT_DEVMINOR:
                case AUDIT_EXIT:
                case AUDIT_SUCCESS:
                case AUDIT_ARG0:
                case AUDIT_ARG1:
                case AUDIT_ARG2:
                case AUDIT_ARG3:
                        break;
                case AUDIT_ARCH:
                        entry->rule.arch_f = f;
                        break;
                case AUDIT_SUBJ_USER:
                case AUDIT_SUBJ_ROLE:
                case AUDIT_SUBJ_TYPE:
                case AUDIT_SUBJ_SEN:
                case AUDIT_SUBJ_CLR:
                case AUDIT_OBJ_USER:
                case AUDIT_OBJ_ROLE:
                case AUDIT_OBJ_TYPE:
                case AUDIT_OBJ_LEV_LOW:
                case AUDIT_OBJ_LEV_HIGH:
                        str = audit_unpack_string(&bufp, &remain, f->val);
                        if (IS_ERR(str))
                                goto exit_free;
                        entry->rule.buflen += f->val;

                        err = security_audit_rule_init(f->type, f->op, str,
                                                       (void **)&f->lsm_rule);
                        /* Keep currently invalid fields around in case they
                         * become valid after a policy reload. */
                        if (err == -EINVAL) {
                                printk(KERN_WARNING "audit rule for LSM "
                                       "\'%s\' is invalid\n",  str);
                                err = 0;
                        }
                        if (err) {
                                kfree(str);
                                goto exit_free;
                        } else
                                f->lsm_str = str;
                        break;
                case AUDIT_WATCH:
                        str = audit_unpack_string(&bufp, &remain, f->val);
                        if (IS_ERR(str))
                                goto exit_free;
                        entry->rule.buflen += f->val;

                        err = audit_to_watch(&entry->rule, str, f->val, f->op);
                        if (err) {
                                kfree(str);
                                goto exit_free;
                        }
                        break;
                case AUDIT_DIR:
                        str = audit_unpack_string(&bufp, &remain, f->val);
                        if (IS_ERR(str))
                                goto exit_free;
                        entry->rule.buflen += f->val;

                        err = audit_make_tree(&entry->rule, str, f->op);
                        kfree(str);
                        if (err)
                                goto exit_free;
                        break;
                case AUDIT_INODE:
                        err = audit_to_inode(&entry->rule, f);
                        if (err)
                                goto exit_free;
                        break;
                case AUDIT_FILTERKEY:
                        err = -EINVAL;
                        if (entry->rule.filterkey || f->val > AUDIT_MAX_KEY_LEN)
                                goto exit_free;
                        str = audit_unpack_string(&bufp, &remain, f->val);
                        if (IS_ERR(str))
                                goto exit_free;
                        entry->rule.buflen += f->val;
                        entry->rule.filterkey = str;
                        break;
                case AUDIT_PERM:
                        if (f->val & ~15)
                                goto exit_free;
                        break;
                case AUDIT_FILETYPE:
                        if ((f->val & ~S_IFMT) > S_IFMT)
                                goto exit_free;
                        break;
                default:
                        goto exit_free;
                }
        }

        ino_f = entry->rule.inode_f;
        if (ino_f) {
                switch(ino_f->op) {
                case AUDIT_NOT_EQUAL:
                        entry->rule.inode_f = NULL;
                case AUDIT_EQUAL:
                        break;
                default:
                        err = -EINVAL;
                        goto exit_free;
                }
        }

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

        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 NULL;
        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_SUBJ_USER:
                case AUDIT_SUBJ_ROLE:
                case AUDIT_SUBJ_TYPE:
                case AUDIT_SUBJ_SEN:
                case AUDIT_SUBJ_CLR:
                case AUDIT_OBJ_USER:
                case AUDIT_OBJ_ROLE:
                case AUDIT_OBJ_TYPE:
                case AUDIT_OBJ_LEV_LOW:
                case AUDIT_OBJ_LEV_HIGH:
                        data->buflen += data->values[i] =
                                audit_pack_string(&bufp, f->lsm_str);
                        break;
                case AUDIT_WATCH:
                        data->buflen += data->values[i] =
                                audit_pack_string(&bufp, krule->watch->path);
                        break;
                case AUDIT_DIR:
                        data->buflen += data->values[i] =
                                audit_pack_string(&bufp,
                                                  audit_tree_path(krule->tree));
                        break;
                case AUDIT_FILTERKEY:
                        data->buflen += data->values[i] =
                                audit_pack_string(&bufp, krule->filterkey);
                        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_SUBJ_USER:
                case AUDIT_SUBJ_ROLE:
                case AUDIT_SUBJ_TYPE:
                case AUDIT_SUBJ_SEN:
                case AUDIT_SUBJ_CLR:
                case AUDIT_OBJ_USER:
                case AUDIT_OBJ_ROLE:
                case AUDIT_OBJ_TYPE:
                case AUDIT_OBJ_LEV_LOW:
                case AUDIT_OBJ_LEV_HIGH:
                        if (strcmp(a->fields[i].lsm_str, b->fields[i].lsm_str))
                                return 1;
                        break;
                case AUDIT_WATCH:
                        if (strcmp(a->watch->path, b->watch->path))
                                return 1;
                        break;
                case AUDIT_DIR:
                        if (strcmp(audit_tree_path(a->tree),
                                   audit_tree_path(b->tree)))
                                return 1;
                        break;
                case AUDIT_FILTERKEY:
                        /* both filterkeys exist based on above type compare */
                        if (strcmp(a->filterkey, b->filterkey))
                                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 the given audit watch.  The new watch's rules list is initialized
 * to an empty list and wlist is undefined. */
static struct audit_watch *audit_dupe_watch(struct audit_watch *old)
{
        char *path;
        struct audit_watch *new;

        path = kstrdup(old->path, GFP_KERNEL);
        if (unlikely(!path))
                return ERR_PTR(-ENOMEM);

        new = audit_init_watch(path);
        if (IS_ERR(new)) {
                kfree(path);
                goto out;
        }

        new->dev = old->dev;
        new->ino = old->ino;
        get_inotify_watch(&old->parent->wdata);
        new->parent = old->parent;

out:
        return new;
}

/* Duplicate LSM field information.  The lsm_rule is opaque, so must be
 * re-initialized. */
static inline int audit_dupe_lsm_field(struct audit_field *df,
                                           struct audit_field *sf)
{
        int ret = 0;
        char *lsm_str;

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

        /* our own (refreshed) copy of lsm_rule */
        ret = security_audit_rule_init(df->type, df->op, df->lsm_str,
                                       (void **)&df->lsm_rule);
        /* Keep currently invalid fields around in case they
         * become valid after a policy reload. */
        if (ret == -EINVAL) {
                printk(KERN_WARNING "audit rule for LSM \'%s\' is "
                       "invalid\n", df->lsm_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 LSM 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.
 * The rlist element is undefined; list manipulations are handled apart from
 * the initial copy. */
static struct audit_entry *audit_dupe_rule(struct audit_krule *old,
                                           struct audit_watch *watch)
{
        u32 fcount = old->field_count;
        struct audit_entry *entry;
        struct audit_krule *new;
        char *fk;
        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->inode_f = old->inode_f;
        new->watch = NULL;
        new->field_count = old->field_count;
        /*
         * note that we are OK with not refcounting here; audit_match_tree()
         * never dereferences tree and we can't get false positives there
         * since we'd have to have rule gone from the list *and* removed
         * before the chunks found by lookup had been allocated, i.e. before
         * the beginning of list scan.
         */
        new->tree = old->tree;
        memcpy(new->fields, old->fields, sizeof(struct audit_field) * fcount);

        /* deep copy this information, updating the lsm_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_SUBJ_USER:
                case AUDIT_SUBJ_ROLE:
                case AUDIT_SUBJ_TYPE:
                case AUDIT_SUBJ_SEN:
                case AUDIT_SUBJ_CLR:
                case AUDIT_OBJ_USER:
                case AUDIT_OBJ_ROLE:
                case AUDIT_OBJ_TYPE:
                case AUDIT_OBJ_LEV_LOW:
                case AUDIT_OBJ_LEV_HIGH:
                        err = audit_dupe_lsm_field(&new->fields[i],
                                                       &old->fields[i]);
                        break;
                case AUDIT_FILTERKEY:
                        fk = kstrdup(old->filterkey, GFP_KERNEL);
                        if (unlikely(!fk))
                                err = -ENOMEM;
                        else
                                new->filterkey = fk;
                }
                if (err) {
                        audit_free_rule(entry);
                        return ERR_PTR(err);
                }
        }

        if (watch) {
                audit_get_watch(watch);
                new->watch = watch;
        }

        return entry;
}

/* Update inode info in audit rules based on filesystem event. */
static void audit_update_watch(struct audit_parent *parent,
                               const char *dname, dev_t dev,
                               unsigned long ino, unsigned invalidating)
{
        struct audit_watch *owatch, *nwatch, *nextw;
        struct audit_krule *r, *nextr;
        struct audit_entry *oentry, *nentry;

        mutex_lock(&audit_filter_mutex);
        list_for_each_entry_safe(owatch, nextw, &parent->watches, wlist) {
                if (audit_compare_dname_path(dname, owatch->path, NULL))
                        continue;

                /* If the update involves invalidating rules, do the inode-based
                 * filtering now, so we don't omit records. */
                if (invalidating && current->audit_context &&
                    audit_filter_inodes(current, current->audit_context) == AUDIT_RECORD_CONTEXT)
                        audit_set_auditable(current->audit_context);

                nwatch = audit_dupe_watch(owatch);
                if (IS_ERR(nwatch)) {
                        mutex_unlock(&audit_filter_mutex);
                        audit_panic("error updating watch, skipping");
                        return;
                }
                nwatch->dev = dev;

                nwatch->ino = ino;

                list_for_each_entry_safe(r, nextr, &owatch->rules, rlist) {

                        oentry = container_of(r, struct audit_entry, rule);
                        list_del(&oentry->rule.rlist);
                        list_del_rcu(&oentry->list);

                        nentry = audit_dupe_rule(&oentry->rule, nwatch);
                        if (IS_ERR(nentry))
                                audit_panic("error updating watch, removing");
                        else {
                                int h = audit_hash_ino((u32)ino);
                                list_add(&nentry->rule.rlist, &nwatch->rules);
                                list_add_rcu(&nentry->list, &audit_inode_hash[h]);
                        }

                        call_rcu(&oentry->rcu, audit_free_rule_rcu);
                }

                if (audit_enabled) {
                        struct audit_buffer *ab;
                        ab = audit_log_start(NULL, GFP_KERNEL,
                                AUDIT_CONFIG_CHANGE);
                        audit_log_format(ab,
                                "op=updated rules specifying path=");
                        audit_log_untrustedstring(ab, owatch->path);
                        audit_log_format(ab, " with dev=%u ino=%lu\n",
                                 dev, ino);
                        audit_log_format(ab, " list=%d res=1", r->listnr);
                        audit_log_end(ab);
                }
                audit_remove_watch(owatch);
                goto add_watch_to_parent; /* event applies to a single watch */
        }
        mutex_unlock(&audit_filter_mutex);
        return;

add_watch_to_parent:
        list_add(&nwatch->wlist, &parent->watches);
        mutex_unlock(&audit_filter_mutex);
        return;
}

/* Remove all watches & rules associated with a parent that is going away. */
static void audit_remove_parent_watches(struct audit_parent *parent)
{
        struct audit_watch *w, *nextw;
        struct audit_krule *r, *nextr;
        struct audit_entry *e;

        mutex_lock(&audit_filter_mutex);
        parent->flags |= AUDIT_PARENT_INVALID;
        list_for_each_entry_safe(w, nextw, &parent->watches, wlist) {
                list_for_each_entry_safe(r, nextr, &w->rules, rlist) {
                        e = container_of(r, struct audit_entry, rule);
                        if (audit_enabled) {
                                struct audit_buffer *ab;
                                ab = audit_log_start(NULL, GFP_KERNEL,
                                        AUDIT_CONFIG_CHANGE);
                                audit_log_format(ab, "op=remove rule path=");
                                audit_log_untrustedstring(ab, w->path);
                                if (r->filterkey) {
                                        audit_log_format(ab, " key=");
                                        audit_log_untrustedstring(ab,
                                                        r->filterkey);
                                } else
                                        audit_log_format(ab, " key=(null)");
                                audit_log_format(ab, " list=%d res=1",
                                        r->listnr);
                                audit_log_end(ab);
                        }
                        list_del(&r->rlist);
                        list_del_rcu(&e->list);
                        call_rcu(&e->rcu, audit_free_rule_rcu);
                }
                audit_remove_watch(w);
        }
        mutex_unlock(&audit_filter_mutex);
}

/* Unregister inotify watches for parents on in_list.
 * Generates an IN_IGNORED event. */
static void audit_inotify_unregister(struct list_head *in_list)
{
        struct audit_parent *p, *n;

        list_for_each_entry_safe(p, n, in_list, ilist) {
                list_del(&p->ilist);
                inotify_rm_watch(audit_ih, &p->wdata);
                /* the put matching the get in audit_do_del_rule() */
                put_inotify_watch(&p->wdata);
        }
}

/* Find an existing audit rule.
 * Caller must hold audit_filter_mutex to prevent stale rule data. */
static struct audit_entry *audit_find_rule(struct audit_entry *entry,
                                           struct list_head *list)
{
        struct audit_entry *e, *found = NULL;
        int h;

        if (entry->rule.watch) {
                /* we don't know the inode number, so must walk entire hash */
                for (h = 0; h < AUDIT_INODE_BUCKETS; h++) {
                        list = &audit_inode_hash[h];
                        list_for_each_entry(e, list, list)
                                if (!audit_compare_rule(&entry->rule, &e->rule)) {
                                        found = e;
                                        goto out;
                                }
                }
                goto out;
        }

        list_for_each_entry(e, list, list)
                if (!audit_compare_rule(&entry->rule, &e->rule)) {
                        found = e;
                        goto out;
                }

out:
        return found;
}

/* Get path information necessary for adding watches. */
static int audit_get_nd(char *path, struct nameidata **ndp,
                        struct nameidata **ndw)
{
        struct nameidata *ndparent, *ndwatch;
        int err;

        ndparent = kmalloc(sizeof(*ndparent), GFP_KERNEL);
        if (unlikely(!ndparent))
                return -ENOMEM;

        ndwatch = kmalloc(sizeof(*ndwatch), GFP_KERNEL);
        if (unlikely(!ndwatch)) {
                kfree(ndparent);
                return -ENOMEM;
        }

        err = path_lookup(path, LOOKUP_PARENT, ndparent);
        if (err) {
                kfree(ndparent);
                kfree(ndwatch);
                return err;
        }

        err = path_lookup(path, 0, ndwatch);
        if (err) {
                kfree(ndwatch);
                ndwatch = NULL;
        }

        *ndp = ndparent;
        *ndw = ndwatch;

        return 0;
}

/* Release resources used for watch path information. */
static void audit_put_nd(struct nameidata *ndp, struct nameidata *ndw)
{
        if (ndp) {
                path_put(&ndp->path);
                kfree(ndp);
        }
        if (ndw) {
                path_put(&ndw->path);
                kfree(ndw);
        }
}

/* Associate the given rule with an existing parent inotify_watch.
 * Caller must hold audit_filter_mutex. */
static void audit_add_to_parent(struct audit_krule *krule,
                                struct audit_parent *parent)
{
        struct audit_watch *w, *watch = krule->watch;
        int watch_found = 0;

        list_for_each_entry(w, &parent->watches, wlist) {
                if (strcmp(watch->path, w->path))
                        continue;

                watch_found = 1;

                /* put krule's and initial refs to temporary watch */
                audit_put_watch(watch);
                audit_put_watch(watch);

                audit_get_watch(w);
                krule->watch = watch = w;
                break;
        }

        if (!watch_found) {
                get_inotify_watch(&parent->wdata);
                watch->parent = parent;

                list_add(&watch->wlist, &parent->watches);
        }
        list_add(&krule->rlist, &watch->rules);
}

/* Find a matching watch entry, or add this one.
 * Caller must hold audit_filter_mutex. */
static int audit_add_watch(struct audit_krule *krule, struct nameidata *ndp,
                           struct nameidata *ndw)
{
        struct audit_watch *watch = krule->watch;
        struct inotify_watch *i_watch;
        struct audit_parent *parent;
        int ret = 0;

        /* update watch filter fields */
        if (ndw) {
                watch->dev = ndw->path.dentry->d_inode->i_sb->s_dev;
                watch->ino = ndw->path.dentry->d_inode->i_ino;
        }

        /* The audit_filter_mutex must not be held during inotify calls because
         * we hold it during inotify event callback processing.  If an existing
         * inotify watch is found, inotify_find_watch() grabs a reference before
         * returning.
         */
        mutex_unlock(&audit_filter_mutex);

        if (inotify_find_watch(audit_ih, ndp->path.dentry->d_inode,
                               &i_watch) < 0) {
                parent = audit_init_parent(ndp);
                if (IS_ERR(parent)) {
                        /* caller expects mutex locked */
                        mutex_lock(&audit_filter_mutex);
                        return PTR_ERR(parent);
                }
        } else
                parent = container_of(i_watch, struct audit_parent, wdata);

        mutex_lock(&audit_filter_mutex);

        /* parent was moved before we took audit_filter_mutex */
        if (parent->flags & AUDIT_PARENT_INVALID)
                ret = -ENOENT;
        else
                audit_add_to_parent(krule, parent);

        /* match get in audit_init_parent or inotify_find_watch */
        put_inotify_watch(&parent->wdata);
        return ret;
}

/* Add rule to given filterlist if not a duplicate. */
static inline int audit_add_rule(struct audit_entry *entry,
                                 struct list_head *list)
{
        struct audit_entry *e;
        struct audit_field *inode_f = entry->rule.inode_f;
        struct audit_watch *watch = entry->rule.watch;
        struct audit_tree *tree = entry->rule.tree;
        struct nameidata *ndp = NULL, *ndw = NULL;
        int h, err;
#ifdef CONFIG_AUDITSYSCALL
        int dont_count = 0;

        /* If either of these, don't count towards total */
        if (entry->rule.listnr == AUDIT_FILTER_USER ||
                entry->rule.listnr == AUDIT_FILTER_TYPE)
                dont_count = 1;
#endif

        if (inode_f) {
                h = audit_hash_ino(inode_f->val);
                list = &audit_inode_hash[h];
        }

        mutex_lock(&audit_filter_mutex);
        e = audit_find_rule(entry, list);
        mutex_unlock(&audit_filter_mutex);
        if (e) {
                err = -EEXIST;
                /* normally audit_add_tree_rule() will free it on failure */
                if (tree)
                        audit_put_tree(tree);
                goto error;
        }

        /* Avoid calling path_lookup under audit_filter_mutex. */
        if (watch) {
                err = audit_get_nd(watch->path, &ndp, &ndw);
                if (err)
                        goto error;
        }

        mutex_lock(&audit_filter_mutex);
        if (watch) {
                /* audit_filter_mutex is dropped and re-taken during this call */
                err = audit_add_watch(&entry->rule, ndp, ndw);
                if (err) {
                        mutex_unlock(&audit_filter_mutex);
                        goto error;
                }
                h = audit_hash_ino((u32)watch->ino);
                list = &audit_inode_hash[h];
        }
        if (tree) {
                err = audit_add_tree_rule(&entry->rule);
                if (err) {
                        mutex_unlock(&audit_filter_mutex);
                        goto error;
                }
        }

        if (entry->rule.flags & AUDIT_FILTER_PREPEND) {
                list_add_rcu(&entry->list, list);
                entry->rule.flags &= ~AUDIT_FILTER_PREPEND;
        } else {
                list_add_tail_rcu(&entry->list, list);
        }
#ifdef CONFIG_AUDITSYSCALL
        if (!dont_count)
                audit_n_rules++;

        if (!audit_match_signal(entry))
                audit_signals++;
#endif
        mutex_unlock(&audit_filter_mutex);

        audit_put_nd(ndp, ndw);         /* NULL args OK */
        return 0;

error:
        audit_put_nd(ndp, ndw);         /* NULL args OK */
        if (watch)
                audit_put_watch(watch); /* tmp watch, matches initial get */
        return err;
}

/* Remove an existing rule from filterlist. */
static inline int audit_del_rule(struct audit_entry *entry,
                                 struct list_head *list)
{
        struct audit_entry  *e;
        struct audit_field *inode_f = entry->rule.inode_f;
        struct audit_watch *watch, *tmp_watch = entry->rule.watch;
        struct audit_tree *tree = entry->rule.tree;
        LIST_HEAD(inotify_list);
        int h, ret = 0;
#ifdef CONFIG_AUDITSYSCALL
        int dont_count = 0;

        /* If either of these, don't count towards total */
        if (entry->rule.listnr == AUDIT_FILTER_USER ||
                entry->rule.listnr == AUDIT_FILTER_TYPE)
                dont_count = 1;
#endif

        if (inode_f) {
                h = audit_hash_ino(inode_f->val);
                list = &audit_inode_hash[h];
        }

        mutex_lock(&audit_filter_mutex);
        e = audit_find_rule(entry, list);
        if (!e) {
                mutex_unlock(&audit_filter_mutex);
                ret = -ENOENT;
                goto out;
        }

        watch = e->rule.watch;
        if (watch) {
                struct audit_parent *parent = watch->parent;

                list_del(&e->rule.rlist);

                if (list_empty(&watch->rules)) {
                        audit_remove_watch(watch);

                        if (list_empty(&parent->watches)) {
                                /* Put parent on the inotify un-registration
                                 * list.  Grab a reference before releasing
                                 * audit_filter_mutex, to be released in
                                 * audit_inotify_unregister(). */
                                list_add(&parent->ilist, &inotify_list);
                                get_inotify_watch(&parent->wdata);
                        }
                }
        }

        if (e->rule.tree)
                audit_remove_tree_rule(&e->rule);

        list_del_rcu(&e->list);
        call_rcu(&e->rcu, audit_free_rule_rcu);

#ifdef CONFIG_AUDITSYSCALL
        if (!dont_count)
                audit_n_rules--;

        if (!audit_match_signal(entry))
                audit_signals--;
#endif
        mutex_unlock(&audit_filter_mutex);

        if (!list_empty(&inotify_list))
                audit_inotify_unregister(&inotify_list);

out:
        if (tmp_watch)
                audit_put_watch(tmp_watch); /* match initial get */
        if (tree)
                audit_put_tree(tree);   /* that's the temporary one */

        return ret;
}

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

        /* This is a blocking read, so use audit_filter_mutex instead of rcu
         * iterator to sync with list writers. */
        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;
                        skb = audit_make_reply(pid, seq, AUDIT_LIST, 0, 1,
                                         rule, sizeof(*rule));
                        if (skb)
                                skb_queue_tail(q, skb);
                        kfree(rule);
                }
        }
        for (i = 0; i < AUDIT_INODE_BUCKETS; i++) {
                list_for_each_entry(entry, &audit_inode_hash[i], list) {
                        struct audit_rule *rule;

                        rule = audit_krule_to_rule(&entry->rule);
                        if (unlikely(!rule))
                                break;
                        skb = audit_make_reply(pid, seq, AUDIT_LIST, 0, 1,
                                         rule, sizeof(*rule));
                        if (skb)
                                skb_queue_tail(q, skb);
                        kfree(rule);
                }
        }
        skb = audit_make_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
        if (skb)
                skb_queue_tail(q, skb);
}

/* List rules using struct audit_rule_data. */
static void audit_list_rules(int pid, int seq, struct sk_buff_head *q)
{
        struct sk_buff *skb;
        struct audit_entry *e;
        int i;

        /* This is a blocking read, so use audit_filter_mutex instead of rcu
         * iterator to sync with list writers. */
        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;
                        skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 0, 1,
                                         data, sizeof(*data) + data->buflen);
                        if (skb)
                                skb_queue_tail(q, skb);
                        kfree(data);
                }
        }
        for (i=0; i< AUDIT_INODE_BUCKETS; i++) {
                list_for_each_entry(e, &audit_inode_hash[i], list) {
                        struct audit_rule_data *data;

                        data = audit_krule_to_data(&e->rule);
                        if (unlikely(!data))
                                break;
                        skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 0, 1,
                                         data, sizeof(*data) + data->buflen);
                        if (skb)
                                skb_queue_tail(q, skb);
                        kfree(data);
                }
        }
        skb = audit_make_reply(pid, seq, AUDIT_LIST_RULES, 1, 1, NULL, 0);
        if (skb)
                skb_queue_tail(q, skb);
}

/* Log rule additions and removals */
static void audit_log_rule_change(uid_t loginuid, u32 sessionid, u32 sid,
                                  char *action, struct audit_krule *rule,
                                  int res)
{
        struct audit_buffer *ab;

        if (!audit_enabled)
                return;

        ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
        if (!ab)
                return;
        audit_log_format(ab, "auid=%u ses=%u", loginuid, sessionid);
        if (sid) {
                char *ctx = NULL;
                u32 len;
                if (security_secid_to_secctx(sid, &ctx, &len))
                        audit_log_format(ab, " ssid=%u", sid);
                else {
                        audit_log_format(ab, " subj=%s", ctx);
                        security_release_secctx(ctx, len);
                }
        }
        audit_log_format(ab, " op=%s rule key=", action);
        if (rule->filterkey)
                audit_log_untrustedstring(ab, rule->filterkey);
        else
                audit_log_format(ab, "(null)");
        audit_log_format(ab, " list=%d res=%d", rule->listnr, res);
        audit_log_end(ab);
}

/**
 * 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
 * @sessionid: sessionid for netlink audit message
 * @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 sessionid, u32 sid)
{
        struct task_struct *tsk;
        struct audit_netlink_list *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(sizeof(struct audit_netlink_list), GFP_KERNEL);
                if (!dest)
                        return -ENOMEM;
                dest->pid = pid;
                skb_queue_head_init(&dest->q);

                mutex_lock(&audit_filter_mutex);
                if (type == AUDIT_LIST)
                        audit_list(pid, seq, &dest->q);
                else
                        audit_list_rules(pid, seq, &dest->q);
                mutex_unlock(&audit_filter_mutex);

                tsk = kthread_run(audit_send_list, dest, "audit_send_list");
                if (IS_ERR(tsk)) {
                        skb_queue_purge(&dest->q);
                        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]);
                audit_log_rule_change(loginuid, sessionid, sid, "add",
                                      &entry->rule, !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]);
                audit_log_rule_change(loginuid, sessionid, sid, "remove",
                                      &entry->rule, !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);
        case AUDIT_BIT_MASK:
                return (left & right);
        case AUDIT_BIT_TEST:
                return ((left & right) == right);
        }
        BUG();
        return 0;
}

/* Compare given dentry name with last component in given path,
 * return of 0 indicates a match. */
int audit_compare_dname_path(const char *dname, const char *path,
                             int *dirlen)
{
        int dlen, plen;
        const char *p;

        if (!dname || !path)
                return 1;

        dlen = strlen(dname);
        plen = strlen(path);
        if (plen < dlen)
                return 1;

        /* disregard trailing slashes */
        p = path + plen - 1;
        while ((*p == '/') && (p > path))
                p--;

        /* find last path component */
        p = p - dlen + 1;
        if (p < path)
                return 1;
        else if (p > path) {
                if (*--p != '/')
                        return 1;
                else
                        p++;
        }

        /* return length of path's directory component */
        if (dirlen)
                *dirlen = p - path;
        return strncmp(p, dname, dlen);
}

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_ALWAYS:   *state = AUDIT_RECORD_CONTEXT; break;
        }
        return 1;
}

int audit_filter_user(struct netlink_skb_parms *cb)
{
        enum audit_state state = AUDIT_DISABLED;
        struct audit_entry *e;
        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;
}

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

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

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

                        watch = entry->rule.watch;
                        tree = entry->rule.tree;
                        nentry = audit_dupe_rule(&entry->rule, watch);
                        if (IS_ERR(nentry)) {
                                /* save the first error encountered for the
                                 * return value */
                                if (!err)
                                        err = PTR_ERR(nentry);
                                audit_panic("error updating LSM filters");
                                if (watch)
                                        list_del(&entry->rule.rlist);
                                list_del_rcu(&entry->list);
                        } else {
                                if (watch) {
                                        list_add(&nentry->rule.rlist,
                                                 &watch->rules);
                                        list_del(&entry->rule.rlist);
                                } else if (tree)
                                        list_replace_init(&entry->rule.rlist,
                                                     &nentry->rule.rlist);
                                list_replace_rcu(&entry->list, &nentry->list);
                        }
                        call_rcu(&entry->rcu, audit_free_rule_rcu);
                }
        }

        mutex_unlock(&audit_filter_mutex);

        return err;
}

/* Update watch data in audit rules based on inotify events. */
void audit_handle_ievent(struct inotify_watch *i_watch, u32 wd, u32 mask,
                         u32 cookie, const char *dname, struct inode *inode)
{
        struct audit_parent *parent;

        parent = container_of(i_watch, struct audit_parent, wdata);

        if (mask & (IN_CREATE|IN_MOVED_TO) && inode)
                audit_update_watch(parent, dname, inode->i_sb->s_dev,
                                   inode->i_ino, 0);
        else if (mask & (IN_DELETE|IN_MOVED_FROM))
                audit_update_watch(parent, dname, (dev_t)-1, (unsigned long)-1, 1);
        /* inotify automatically removes the watch and sends IN_IGNORED */
        else if (mask & (IN_DELETE_SELF|IN_UNMOUNT))
                audit_remove_parent_watches(parent);
        /* inotify does not remove the watch, so remove it manually */
        else if(mask & IN_MOVE_SELF) {
                audit_remove_parent_watches(parent);
                inotify_remove_watch_locked(audit_ih, i_watch);
        } else if (mask & IN_IGNORED)
                put_inotify_watch(i_watch);
}