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Commit 3c789a19 authored by Amy Griffis's avatar Amy Griffis Committed by David Woodhouse
Browse files

AUDIT: Prevent duplicate syscall rules 



The following patch against audit.81 prevents duplicate syscall rules in
a given filter list by walking the list on each rule add.

I also removed the unused struct audit_entry in audit.c and made the
static inlines in auditsc.c consistent.

Signed-off-by: default avatarAmy Griffis <amy.griffis@hp.com>
Signed-off-by: default avatarDavid Woodhouse <dwmw2@infradead.org>
parent c3896495

kernel/audit.c

+0 −5
Original line number Diff line number Diff line
@@ -142,11 +142,6 @@ static void audit_set_pid(struct audit_buffer *ab, pid_t pid) 
	nlh->nlmsg_pid = pid;

}



struct audit_entry {

	struct list_head  list;

	struct audit_rule rule;

};



static void audit_panic(const char *message)

{

	switch (audit_failure)

kernel/auditsc.c

+56 −39
Original line number Diff line number Diff line
@@ -190,9 +190,36 @@ struct audit_entry { 


extern int audit_pid;



/* Copy rule from user-space to kernel-space.  Called from 

 * audit_add_rule during AUDIT_ADD. */

static inline int audit_copy_rule(struct audit_rule *d, struct audit_rule *s)

{

	int i;



	if (s->action != AUDIT_NEVER

	    && s->action != AUDIT_POSSIBLE

	    && s->action != AUDIT_ALWAYS)

		return -1;

	if (s->field_count < 0 || s->field_count > AUDIT_MAX_FIELDS)

		return -1;

	if ((s->flags & ~AUDIT_FILTER_PREPEND) >= AUDIT_NR_FILTERS)

		return -1;



	d->flags	= s->flags;

	d->action	= s->action;

	d->field_count	= s->field_count;

	for (i = 0; i < d->field_count; i++) {

		d->fields[i] = s->fields[i];

		d->values[i] = s->values[i];

	}

	for (i = 0; i < AUDIT_BITMASK_SIZE; i++) d->mask[i] = s->mask[i];

	return 0;

}



/* Check to see if two rules are identical.  It is called from

 * audit_add_rule during AUDIT_ADD and 

 * audit_del_rule during AUDIT_DEL. */

static int audit_compare_rule(struct audit_rule *a, struct audit_rule *b)

static inline int audit_compare_rule(struct audit_rule *a, struct audit_rule *b)

{

	int i;
@@ -221,18 +248,37 @@ static int audit_compare_rule(struct audit_rule *a, struct audit_rule *b) 
/* Note that audit_add_rule and audit_del_rule are called via

 * audit_receive() in audit.c, and are protected by

 * audit_netlink_sem. */

static inline void audit_add_rule(struct audit_entry *entry,

static inline int audit_add_rule(struct audit_rule *rule,

				  struct list_head *list)

{

	struct audit_entry  *entry;



	/* Do not use the _rcu iterator here, since this is the only

	 * addition routine. */

	list_for_each_entry(entry, list, list) {

		if (!audit_compare_rule(rule, &entry->rule)) {

			return -EEXIST;

		}

	}



	if (!(entry = kmalloc(sizeof(*entry), GFP_KERNEL)))

		return -ENOMEM;

	if (audit_copy_rule(&entry->rule, rule)) {

		kfree(entry);

		return -EINVAL;

	}



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

		entry->rule.flags &= ~AUDIT_FILTER_PREPEND;

		list_add_rcu(&entry->list, list);

	} else {

		list_add_tail_rcu(&entry->list, list);

	}



	return 0;

}



static void audit_free_rule(struct rcu_head *head)

static inline void audit_free_rule(struct rcu_head *head)

{

	struct audit_entry *e = container_of(head, struct audit_entry, rcu);

	kfree(e);
@@ -258,32 +304,6 @@ static inline int audit_del_rule(struct audit_rule *rule, 
	return -ENOENT;		/* No matching rule */

}



/* Copy rule from user-space to kernel-space.  Called during

 * AUDIT_ADD. */

static int audit_copy_rule(struct audit_rule *d, struct audit_rule *s)

{

	int i;



	if (s->action != AUDIT_NEVER

	    && s->action != AUDIT_POSSIBLE

	    && s->action != AUDIT_ALWAYS)

		return -1;

	if (s->field_count < 0 || s->field_count > AUDIT_MAX_FIELDS)

		return -1;

	if ((s->flags & ~AUDIT_FILTER_PREPEND) >= AUDIT_NR_FILTERS)

		return -1;



	d->flags	= s->flags;

	d->action	= s->action;

	d->field_count	= s->field_count;

	for (i = 0; i < d->field_count; i++) {

		d->fields[i] = s->fields[i];

		d->values[i] = s->values[i];

	}

	for (i = 0; i < AUDIT_BITMASK_SIZE; i++) d->mask[i] = s->mask[i];

	return 0;

}



static int audit_list_rules(void *_dest)

{

	int pid, seq;
@@ -313,7 +333,6 @@ static int audit_list_rules(void *_dest) 
int audit_receive_filter(int type, int pid, int uid, int seq, void *data,

							uid_t loginuid)

{

	struct audit_entry *entry;

	struct task_struct *tsk;

	int *dest;

	int		   err = 0;
@@ -340,14 +359,12 @@ int audit_receive_filter(int type, int pid, int uid, int seq, void *data, 
		}

		break;

	case AUDIT_ADD:

		if (!(entry = kmalloc(sizeof(*entry), GFP_KERNEL)))

			return -ENOMEM;

		if (audit_copy_rule(&entry->rule, data)) {

			kfree(entry);

		listnr =((struct audit_rule *)data)->flags & ~AUDIT_FILTER_PREPEND;

		if (listnr >= AUDIT_NR_FILTERS)

			return -EINVAL;

		}

		listnr = entry->rule.flags & ~AUDIT_FILTER_PREPEND;

		audit_add_rule(entry, &audit_filter_list[listnr]);



		err = audit_add_rule(data, &audit_filter_list[listnr]);

		if (!err)

			audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,

				  "auid=%u added an audit rule\n", loginuid);

		break;