[PATCH] Fix audit record filtering with !CONFIG_AUDITSYSCALL

This fixes the per-user and per-message-type filtering when syscall
auditing isn't enabled.

[AV: folded followup fix from the same author]

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 4 insertions, 376 deletions

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 4ef14515da35..17719b303638 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -52,17 +52,15 @@
 #include <linux/audit.h>
 #include <linux/personality.h>
 #include <linux/time.h>
-#include <linux/kthread.h>
 #include <linux/netlink.h>
 #include <linux/compiler.h>
 #include <asm/unistd.h>
 #include <linux/security.h>
+#include <linux/list.h>
 
-/* 0 = no checking
-   1 = put_count checking
-   2 = verbose put_count checking
-*/
-#define AUDIT_DEBUG 0
+#include "audit.h"
+
+extern struct list_head audit_filter_list[];
 
 /* No syscall auditing will take place unless audit_enabled != 0. */
 extern int audit_enabled;
@@ -76,29 +74,6 @@ extern int audit_enabled;
  * path_lookup. */
 #define AUDIT_NAMES_RESERVED 7
 
-/* At task start time, the audit_state is set in the audit_context using
-   a per-task filter.  At syscall entry, the audit_state is augmented by
-   the syscall filter. */
-enum audit_state {
-	AUDIT_DISABLED,		/* Do not create per-task audit_context.
-				 * No syscall-specific audit records can
-				 * be generated. */
-	AUDIT_SETUP_CONTEXT,	/* Create the per-task audit_context,
-				 * but don't necessarily fill it in at
-				 * syscall entry time (i.e., filter
-				 * instead). */
-	AUDIT_BUILD_CONTEXT,	/* Create the per-task audit_context,
-				 * and always fill it in at syscall
-				 * entry time.  This makes a full
-				 * syscall record available if some
-				 * other part of the kernel decides it
-				 * should be recorded. */
-	AUDIT_RECORD_CONTEXT	/* Create the per-task audit_context,
-				 * always fill it in at syscall entry
-				 * time, and always write out the audit
-				 * record at syscall exit time.  */
-};
-
 /* When fs/namei.c:getname() is called, we store the pointer in name and
  * we don't let putname() free it (instead we free all of the saved
  * pointers at syscall exit time).
@@ -183,264 +158,6 @@ struct audit_context {
 #endif
 };
 
-				/* Public API */
-/* There are three lists of rules -- one to search at task creation
- * time, one to search at syscall entry time, and another to search at
- * syscall exit time. */
-static 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
-};
-
-struct audit_entry {
-	struct list_head  list;
-	struct rcu_head   rcu;
-	struct audit_rule rule;
-};
-
-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 inline int audit_compare_rule(struct audit_rule *a, struct audit_rule *b)
-{
-	int i;
-
-	if (a->flags != b->flags)
-		return 1;
-
-	if (a->action != b->action)
-		return 1;
-
-	if (a->field_count != b->field_count)
-		return 1;
-
-	for (i = 0; i < a->field_count; i++) {
-		if (a->fields[i] != b->fields[i]
-		    || a->values[i] != b->values[i])
-			return 1;
-	}
-
-	for (i = 0; i < AUDIT_BITMASK_SIZE; i++)
-		if (a->mask[i] != b->mask[i])
-			return 1;
-
-	return 0;
-}
-
-/* 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 int audit_add_rule(struct audit_rule *rule,
-				  struct list_head *list)
-{
-	struct audit_entry  *entry;
-	int i;
-
-	/* 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;
-		}
-	}
-
-	for (i = 0; i < rule->field_count; i++) {
-		if (rule->fields[i] & AUDIT_UNUSED_BITS)
-			return -EINVAL;
-		if ( rule->fields[i] & AUDIT_NEGATE )
-			rule->fields[i] |= AUDIT_NOT_EQUAL;
-		else if ( (rule->fields[i] & AUDIT_OPERATORS) == 0 )
-			rule->fields[i] |= AUDIT_EQUAL;
-		rule->fields[i] &= (~AUDIT_NEGATE);
-	}
-
-	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 inline void audit_free_rule(struct rcu_head *head)
-{
-	struct audit_entry *e = container_of(head, struct audit_entry, rcu);
-	kfree(e);
-}
-
-/* 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 int audit_del_rule(struct audit_rule *rule,
-				 struct list_head *list)
-{
-	struct audit_entry  *e;
-
-	/* Do not use the _rcu iterator here, since this is the only
-	 * deletion routine. */
-	list_for_each_entry(e, list, list) {
-		if (!audit_compare_rule(rule, &e->rule)) {
-			list_del_rcu(&e->list);
-			call_rcu(&e->rcu, audit_free_rule);
-			return 0;
-		}
-	}
-	return -ENOENT;		/* No matching rule */
-}
-
-static int audit_list_rules(void *_dest)
-{
-	int pid, seq;
-	int *dest = _dest;
-	struct audit_entry *entry;
-	int i;
-
-	pid = dest[0];
-	seq = dest[1];
-	kfree(dest);
-
-	down(&audit_netlink_sem);
-
-	/* The *_rcu iterators not needed here because we are
-	   always called with audit_netlink_sem held. */
-	for (i=0; i<AUDIT_NR_FILTERS; i++) {
-		list_for_each_entry(entry, &audit_filter_list[i], list)
-			audit_send_reply(pid, seq, AUDIT_LIST, 0, 1,
-					 &entry->rule, sizeof(entry->rule));
-	}
-	audit_send_reply(pid, seq, AUDIT_LIST, 1, 1, NULL, 0);
-	
-	up(&audit_netlink_sem);
-	return 0;
-}
-
-/**
- * audit_receive_filter - apply all rules to the specified message type
- * @type: audit message type
- * @pid: target pid for netlink audit messages
- * @uid: target uid for netlink audit messages
- * @seq: netlink audit message sequence (serial) number
- * @data: payload data
- * @loginuid: loginuid of sender
- */
-int audit_receive_filter(int type, int pid, int uid, int seq, void *data,
-							uid_t loginuid)
-{
-	struct task_struct *tsk;
-	int *dest;
-	int		   err = 0;
-	unsigned listnr;
-
-	switch (type) {
-	case AUDIT_LIST:
-		/* We can't just spew out the rules here because we might fill
-		 * the available socket buffer space and deadlock waiting for
-		 * auditctl to read from it... which isn't ever going to
-		 * happen if we're actually running in the context of auditctl
-		 * trying to _send_ the stuff */
-		 
-		dest = kmalloc(2 * sizeof(int), GFP_KERNEL);
-		if (!dest)
-			return -ENOMEM;
-		dest[0] = pid;
-		dest[1] = seq;
-
-		tsk = kthread_run(audit_list_rules, dest, "audit_list_rules");
-		if (IS_ERR(tsk)) {
-			kfree(dest);
-			err = PTR_ERR(tsk);
-		}
-		break;
-	case AUDIT_ADD:
-		listnr =((struct audit_rule *)data)->flags & ~AUDIT_FILTER_PREPEND;
-		if (listnr >= AUDIT_NR_FILTERS)
-			return -EINVAL;
-
-		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;
-	case AUDIT_DEL:
-		listnr =((struct audit_rule *)data)->flags & ~AUDIT_FILTER_PREPEND;
-		if (listnr >= AUDIT_NR_FILTERS)
-			return -EINVAL;
-
-		err = audit_del_rule(data, &audit_filter_list[listnr]);
-		if (!err)
-			audit_log(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE,
-				  "auid=%u removed an audit rule\n", loginuid);
-		break;
-	default:
-		return -EINVAL;
-	}
-
-	return err;
-}
-
-static 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);
-	default:
-		return -EINVAL;
-	}
-}
 
 /* Compare a task_struct with an audit_rule.  Return 1 on match, 0
  * otherwise. */
@@ -613,95 +330,6 @@ static enum audit_state audit_filter_syscall(struct task_struct *tsk,
 	return AUDIT_BUILD_CONTEXT;
 }
 
-static int audit_filter_user_rules(struct netlink_skb_parms *cb,
-				   struct audit_rule *rule,
-				   enum audit_state *state)
-{
-	int i;
-
-	for (i = 0; i < rule->field_count; i++) {
-		u32 field  = rule->fields[i] & ~AUDIT_OPERATORS;
-		u32 op  = rule->fields[i] & AUDIT_OPERATORS;
-		u32 value  = rule->values[i];
-		int result = 0;
-
-		switch (field) {
-		case AUDIT_PID:
-			result = audit_comparator(cb->creds.pid, op, value);
-			break;
-		case AUDIT_UID:
-			result = audit_comparator(cb->creds.uid, op, value);
-			break;
-		case AUDIT_GID:
-			result = audit_comparator(cb->creds.gid, op, value);
-			break;
-		case AUDIT_LOGINUID:
-			result = audit_comparator(cb->loginuid, op, value);
-			break;
-		}
-
-		if (!result)
-			return 0;
-	}
-	switch (rule->action) {
-	case AUDIT_NEVER:    *state = AUDIT_DISABLED;	    break;
-	case AUDIT_POSSIBLE: *state = AUDIT_BUILD_CONTEXT;  break;
-	case AUDIT_ALWAYS:   *state = AUDIT_RECORD_CONTEXT; break;
-	}
-	return 1;
-}
-
-int audit_filter_user(struct netlink_skb_parms *cb, int type)
-{
-	struct audit_entry *e;
-	enum audit_state   state;
-	int ret = 1;
-
-	rcu_read_lock();
-	list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_USER], list) {
-		if (audit_filter_user_rules(cb, &e->rule, &state)) {
-			if (state == AUDIT_DISABLED)
-				ret = 0;
-			break;
-		}
-	}
-	rcu_read_unlock();
-
-	return ret; /* Audit by default */
-}
-
-int audit_filter_type(int type)
-{
-	struct audit_entry *e;
-	int result = 0;
-	
-	rcu_read_lock();
-	if (list_empty(&audit_filter_list[AUDIT_FILTER_TYPE]))
-		goto unlock_and_return;
-
-	list_for_each_entry_rcu(e, &audit_filter_list[AUDIT_FILTER_TYPE],
-				list) {
-		struct audit_rule *rule = &e->rule;
-		int i;
-		for (i = 0; i < rule->field_count; i++) {
-			u32 field  = rule->fields[i] & ~AUDIT_OPERATORS;
-			u32 op  = rule->fields[i] & AUDIT_OPERATORS;
-			u32 value  = rule->values[i];
-			if ( field == AUDIT_MSGTYPE ) {
-				result = audit_comparator(type, op, value); 
-				if (!result)
-					break;
-			}
-		}
-		if (result)
-			goto unlock_and_return;
-	}
-unlock_and_return:
-	rcu_read_unlock();
-	return result;
-}
-
-
 /* This should be called with task_lock() held. */
 static inline struct audit_context *audit_get_context(struct task_struct *tsk,
 						      int return_valid,