[PATCH] audit: path-based rules

In this implementation, audit registers inotify watches on the parent
directories of paths specified in audit rules.  When audit's inotify
event handler is called, it updates any affected rules based on the
filesystem event.  If the parent directory is renamed, removed, or its
filesystem is unmounted, audit removes all rules referencing that
inotify watch.

To keep things simple, this implementation limits location-based
auditing to the directory entries in an existing directory.  Given
a path-based rule for /foo/bar/passwd, the following table applies:

    passwd modified -- audit event logged
    passwd replaced -- audit event logged, rules list updated
    bar renamed     -- rule removed
    foo renamed     -- untracked, meaning that the rule now applies to
		       the new location

Audit users typically want to have many rules referencing filesystem
objects, which can significantly impact filtering performance.  This
patch also adds an inode-number-based rule hash to mitigate this
situation.

The patch is relative to the audit git tree:
http://kernel.org/git/?p=linux/kernel/git/viro/audit-current.git;a=summary
and uses the inotify kernel API:
http://lkml.org/lkml/2006/6/1/145

Signed-off-by: Amy Griffis <amy.griffis@hp.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 34 insertions, 4 deletions

diff --git a/kernel/audit.h b/kernel/audit.h
index 52cb1e3..58fa44cb 100644
--- a/kernel/audit.h
+++ b/kernel/audit.h
@@ -19,7 +19,6 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
-#include <linux/mutex.h>
 #include <linux/fs.h>
 #include <linux/audit.h>
 #include <linux/skbuff.h>
@@ -54,6 +53,18 @@ enum audit_state {
 };
 
 /* Rule lists */
+struct audit_parent;
+
+struct audit_watch {
+	atomic_t		count;	/* reference count */
+	char			*path;	/* insertion path */
+	dev_t			dev;	/* associated superblock device */
+	unsigned long		ino;	/* associated inode number */
+	struct audit_parent	*parent; /* associated parent */
+	struct list_head	wlist;	/* entry in parent->watches list */
+	struct list_head	rules;	/* associated rules */
+};
+
 struct audit_field {
 	u32				type;
 	u32				val;
@@ -71,6 +82,9 @@ struct audit_krule {
 	u32			buflen; /* for data alloc on list rules */
 	u32			field_count;
 	struct audit_field	*fields;
+	struct audit_field	*inode_f; /* quick access to an inode field */
+	struct audit_watch	*watch;	/* associated watch */
+	struct list_head	rlist;	/* entry in audit_watch.rules list */
 };
 
 struct audit_entry {
@@ -79,10 +93,18 @@ struct audit_entry {
 	struct audit_krule	rule;
 };
 
-
 extern int audit_pid;
-extern int audit_comparator(const u32 left, const u32 op, const u32 right);
 
+#define AUDIT_INODE_BUCKETS	32
+extern struct list_head audit_inode_hash[AUDIT_INODE_BUCKETS];
+
+static inline int audit_hash_ino(u32 ino)
+{
+	return (ino & (AUDIT_INODE_BUCKETS-1));
+}
+
+extern int audit_comparator(const u32 left, const u32 op, const u32 right);
+extern int audit_compare_dname_path(const char *dname, const char *path);
 extern struct sk_buff *	    audit_make_reply(int pid, int seq, int type,
 					     int done, int multi,
 					     void *payload, int size);
@@ -91,7 +113,6 @@ extern void		    audit_send_reply(int pid, int seq, int type,
 					     void *payload, int size);
 extern void		    audit_log_lost(const char *message);
 extern void		    audit_panic(const char *message);
-extern struct mutex audit_netlink_mutex;
 
 struct audit_netlink_list {
 	int pid;
@@ -100,6 +121,10 @@ struct audit_netlink_list {
 
 int audit_send_list(void *);
 
+struct inotify_watch;
+extern void audit_free_parent(struct inotify_watch *);
+extern void audit_handle_ievent(struct inotify_watch *, u32, u32, u32,
+				const char *, struct inode *);
 extern int selinux_audit_rule_update(void);
 
 #ifdef CONFIG_AUDITSYSCALL
@@ -109,6 +134,11 @@ static inline void audit_signal_info(int sig, struct task_struct *t)
 	if (unlikely(audit_pid && t->tgid == audit_pid))
 		__audit_signal_info(sig, t);
 }
+extern enum audit_state audit_filter_inodes(struct task_struct *,
+					    struct audit_context *);
+extern void audit_set_auditable(struct audit_context *);
 #else
 #define audit_signal_info(s,t)
+#define audit_filter_inodes(t,c) AUDIT_DISABLED
+#define audit_set_auditable(c)
 #endif