/* 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/slab.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.
   */

  /* 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
  };

  static struct list_head audit_rules_list[AUDIT_NR_FILTERS] = {
  	LIST_HEAD_INIT(audit_rules_list[0]),
  	LIST_HEAD_INIT(audit_rules_list[1]),
  	LIST_HEAD_INIT(audit_rules_list[2]),
  	LIST_HEAD_INIT(audit_rules_list[3]),
  	LIST_HEAD_INIT(audit_rules_list[4]),
  	LIST_HEAD_INIT(audit_rules_list[5]),
  };

  DEFINE_MUTEX(audit_filter_mutex);

  static inline void audit_free_rule(struct audit_entry *e)

  {

  	int i;

  	struct audit_krule *erule = &e->rule;

  	/* some rules don't have associated watches */

  	if (erule->watch)
  		audit_put_watch(erule->watch);
  	if (erule->fields)
  		for (i = 0; i < erule->field_count; i++) {
  			struct audit_field *f = &erule->fields[i];

  			kfree(f->lsm_str);
  			security_audit_rule_free(f->lsm_rule);

  		}

  	kfree(erule->fields);
  	kfree(erule->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 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 ||
  	    (f->op != Audit_equal && f->op != Audit_not_equal))

  		return -EINVAL;
  
  	krule->inode_f = f;
  	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
  ");
  		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);
  }

  static u32 audit_ops[] =
  {
  	[Audit_equal] = AUDIT_EQUAL,
  	[Audit_not_equal] = AUDIT_NOT_EQUAL,
  	[Audit_bitmask] = AUDIT_BIT_MASK,
  	[Audit_bittest] = AUDIT_BIT_TEST,
  	[Audit_lt] = AUDIT_LESS_THAN,
  	[Audit_gt] = AUDIT_GREATER_THAN,
  	[Audit_le] = AUDIT_LESS_THAN_OR_EQUAL,
  	[Audit_ge] = AUDIT_GREATER_THAN_OR_EQUAL,
  };
  
  static u32 audit_to_op(u32 op)
  {
  	u32 n;
  	for (n = Audit_equal; n < Audit_bad && audit_ops[n] != op; n++)
  		;
  	return n;
  }

  /* 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];

  		u32 n;
  
  		n = rule->fields[i] & (AUDIT_NEGATE|AUDIT_OPERATORS);
  
  		/* Support for legacy operators where
  		 * AUDIT_NEGATE bit signifies != and otherwise assumes == */
  		if (n & AUDIT_NEGATE)
  			f->op = Audit_not_equal;
  		else if (!n)
  			f->op = Audit_equal;
  		else
  			f->op = audit_to_op(n);
  
  		entry->rule.vers_ops = (n & AUDIT_OPERATORS) ? 2 : 1;

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

  		err = -EINVAL;

  		if (f->op == Audit_bad)
  			goto exit_free;

  		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_bitmask || f->op == Audit_bittest)

  				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)

  				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;

  		}

  	}

  	if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
  		entry->rule.inode_f = NULL;

  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;

  
  		f->op = audit_to_op(data->fieldflags[i]);
  		if (f->op == Audit_bad)

  			goto exit_free;

  		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
  ",  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;

  		}
  	}

  	if (entry->rule.inode_f && entry->rule.inode_f->op == Audit_not_equal)
  		entry->rule.inode_f = NULL;

  
  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] |= audit_ops[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] = audit_ops[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,
  						  audit_watch_path(krule->watch));

  			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(audit_watch_path(a->watch),
  				   audit_watch_path(b->watch)))

  				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 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
  ", 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. */

  struct audit_entry *audit_dupe_rule(struct audit_krule *old)

  {
  	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->prio = old->prio;

  	new->buflen = old->buflen;

  	new->inode_f = old->inode_f;

  	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 (old->watch) {
  		audit_get_watch(old->watch);
  		new->watch = old->watch;

  	}

  	return entry;
  }

  /* 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 **p)

  {
  	struct audit_entry *e, *found = NULL;

  	struct list_head *list;

  	int h;

  	if (entry->rule.inode_f) {
  		h = audit_hash_ino(entry->rule.inode_f->val);
  		*p = list = &audit_inode_hash[h];
  	} else 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;

  	} else {
  		*p = list = &audit_filter_list[entry->rule.listnr];

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

  static u64 prio_low = ~0ULL/2;
  static u64 prio_high = ~0ULL/2 - 1;

  /* Add rule to given filterlist if not a duplicate. */

  static inline int audit_add_rule(struct audit_entry *entry)

  {

  	struct audit_entry *e;

  	struct audit_watch *watch = entry->rule.watch;

  	struct audit_tree *tree = entry->rule.tree;

  	struct list_head *list;

  	int 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

  	mutex_lock(&audit_filter_mutex);

  	e = audit_find_rule(entry, &list);

  	if (e) {

  		mutex_unlock(&audit_filter_mutex);

  		err = -EEXIST;

  		/* normally audit_add_tree_rule() will free it on failure */
  		if (tree)
  			audit_put_tree(tree);

  		goto error;
  	}

  	if (watch) {
  		/* audit_filter_mutex is dropped and re-taken during this call */

  		err = audit_add_watch(&entry->rule, &list);

  		if (err) {
  			mutex_unlock(&audit_filter_mutex);
  			goto error;
  		}

  	}

  	if (tree) {
  		err = audit_add_tree_rule(&entry->rule);
  		if (err) {
  			mutex_unlock(&audit_filter_mutex);
  			goto error;
  		}
  	}

  	entry->rule.prio = ~0ULL;
  	if (entry->rule.listnr == AUDIT_FILTER_EXIT) {
  		if (entry->rule.flags & AUDIT_FILTER_PREPEND)
  			entry->rule.prio = ++prio_high;
  		else
  			entry->rule.prio = --prio_low;
  	}

  	if (entry->rule.flags & AUDIT_FILTER_PREPEND) {

  		list_add(&entry->rule.list,
  			 &audit_rules_list[entry->rule.listnr]);

  		list_add_rcu(&entry->list, list);

  		entry->rule.flags &= ~AUDIT_FILTER_PREPEND;

  	} else {

  		list_add_tail(&entry->rule.list,
  			      &audit_rules_list[entry->rule.listnr]);

  		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);

   	return 0;
  
  error:

  	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 audit_entry  *e;

  	struct audit_watch *watch = entry->rule.watch;

  	struct audit_tree *tree = entry->rule.tree;

  	struct list_head *list;

  	int 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

  	mutex_lock(&audit_filter_mutex);

  	e = audit_find_rule(entry, &list);

  	if (!e) {
  		mutex_unlock(&audit_filter_mutex);
  		ret = -ENOENT;
  		goto out;
  	}

  	if (e->rule.watch)

  		audit_remove_watch_rule(&e->rule);

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

  	list_del_rcu(&e->list);

  	list_del(&e->rule.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);

  out:

  	if (watch)
  		audit_put_watch(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_krule *r;

  	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(r, &audit_rules_list[i], list) {

  			struct audit_rule *rule;

  			rule = audit_krule_to_rule(r);

  			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_krule *r;

  	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(r, &audit_rules_list[i], list) {

  			struct audit_rule_data *data;

  			data = audit_krule_to_data(r);

  			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=");
  	audit_log_string(ab, action);
  	audit_log_key(ab, rule->filterkey);

  	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_log_rule_change(loginuid, sessionid, sid, "add rule",

  				      &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_log_rule_change(loginuid, sessionid, sid, "remove rule",

  				      &entry->rule, !err);

  		audit_free_rule(entry);

  		break;
  	default:
  		return -EINVAL;
  	}
  
  	return err;
  }

  int audit_comparator(u32 left, u32 op, u32 right)

  {
  	switch (op) {

  	case Audit_equal:

  		return (left == right);

  	case Audit_not_equal:

  		return (left != right);

  	case Audit_lt:

  		return (left < right);

  	case Audit_le:

  		return (left <= right);

  	case Audit_gt:

  		return (left > right);

  	case Audit_ge:

  		return (left >= right);

  	case Audit_bitmask:

  		return (left & right);

  	case Audit_bittest:

  		return ((left & right) == right);

  	default:
  		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;

  		u32 sid;

  		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(audit_get_loginuid(current),
  						  f->op, f->val);

  			break;

  		case AUDIT_SUBJ_USER:
  		case AUDIT_SUBJ_ROLE:
  		case AUDIT_SUBJ_TYPE:
  		case AUDIT_SUBJ_SEN:
  		case AUDIT_SUBJ_CLR:

  			if (f->lsm_rule) {
  				security_task_getsecid(current, &sid);
  				result = security_audit_rule_match(sid,

  								   f->type,
  								   f->op,
  								   f->lsm_rule,
  								   NULL);

  			}

  			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;
  }

  static int update_lsm_rule(struct audit_krule *r)

  {

  	struct audit_entry *entry = container_of(r, struct audit_entry, rule);

  	struct audit_entry *nentry;

  	int err = 0;

  	if (!security_audit_rule_known(r))

  		return 0;

  	nentry = audit_dupe_rule(r);

  	if (IS_ERR(nentry)) {
  		/* save the first error encountered for the
  		 * return value */
  		err = PTR_ERR(nentry);
  		audit_panic("error updating LSM filters");

  		if (r->watch)

  			list_del(&r->rlist);

  		list_del_rcu(&entry->list);

  		list_del(&r->list);

  	} else {

  		if (r->watch || r->tree)

  			list_replace_init(&r->rlist, &nentry->rule.rlist);

  		list_replace_rcu(&entry->list, &nentry->list);

  		list_replace(&r->list, &nentry->rule.list);

  	}
  	call_rcu(&entry->rcu, audit_free_rule_rcu);
  
  	return err;
  }

  /* 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_krule *r, *n;

  	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(r, n, &audit_rules_list[i], list) {
  			int res = update_lsm_rule(r);

  			if (!err)
  				err = res;

  		}
  	}

  	mutex_unlock(&audit_filter_mutex);

  
  	return err;
  }