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drm_gem_shmem_helper.c

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  • auditfilter.c 33.25 KiB
    /* 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;
    #ifdef CONFIG_AUDITSYSCALL
    	case AUDIT_FILTER_ENTRY:
    		if (rule->action == AUDIT_ALWAYS)
    			goto exit_err;
    	case AUDIT_FILTER_EXIT:
    	case AUDIT_FILTER_TASK:
    #endif
    	case AUDIT_FILTER_USER:
    	case AUDIT_FILTER_TYPE:
    		;
    	}
    	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);
    }
    
    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)
    				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:
    		case AUDIT_OBJ_UID:
    		case AUDIT_OBJ_GID:
    			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)
    				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\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. */
    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;
    }