Commit 250a25e7 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'work.audit' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 

Pull RCU-safe common_lsm_audit() from Al Viro:
 "Make common_lsm_audit() non-blocking and usable from RCU pathwalk
  context.

  We don't really need to grab/drop dentry in there - rcu_read_lock() is
  enough. There's a couple of followups using that to simplify the
  logics in selinux, but those hadn't soaked in -next yet, so they'll
  have to go in next window"

* 'work.audit' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  make dump_common_audit_data() safe to be called from RCU pathwalk
  new helper: d_find_alias_rcu()
parents 205f92d7 23d8f5b6

fs/dcache.c

+25 −0
Original line number Diff line number Diff line
@@ -1043,6 +1043,31 @@ struct dentry *d_find_alias(struct inode *inode) 
}

EXPORT_SYMBOL(d_find_alias);



/*

 *  Caller MUST be holding rcu_read_lock() and be guaranteed

 *  that inode won't get freed until rcu_read_unlock().

 */

struct dentry *d_find_alias_rcu(struct inode *inode)

{

	struct hlist_head *l = &inode->i_dentry;

	struct dentry *de = NULL;



	spin_lock(&inode->i_lock);

	// ->i_dentry and ->i_rcu are colocated, but the latter won't be

	// used without having I_FREEING set, which means no aliases left

	if (likely(!(inode->i_state & I_FREEING) && !hlist_empty(l))) {

		if (S_ISDIR(inode->i_mode)) {

			de = hlist_entry(l->first, struct dentry, d_u.d_alias);

		} else {

			hlist_for_each_entry(de, l, d_u.d_alias)

				if (!d_unhashed(de))

					break;

		}

	}

	spin_unlock(&inode->i_lock);

	return de;

}



/*

 *	Try to kill dentries associated with this inode.

 * WARNING: you must own a reference to inode.

include/linux/dcache.h

+2 −0
Original line number Diff line number Diff line
@@ -262,6 +262,8 @@ extern void d_tmpfile(struct dentry *, struct inode *); 
extern struct dentry *d_find_alias(struct inode *);

extern void d_prune_aliases(struct inode *);



extern struct dentry *d_find_alias_rcu(struct inode *);



/* test whether we have any submounts in a subdir tree */

extern int path_has_submounts(const struct path *);

security/lsm_audit.c

+3 −2
Original line number Diff line number Diff line
@@ -291,18 +291,19 @@ static void dump_common_audit_data(struct audit_buffer *ab, 
		struct dentry *dentry;

		struct inode *inode;



		rcu_read_lock();

		inode = a->u.inode;

		dentry = d_find_alias(inode);

		dentry = d_find_alias_rcu(inode);

		if (dentry) {

			audit_log_format(ab, " name=");

			spin_lock(&dentry->d_lock);

			audit_log_untrustedstring(ab, dentry->d_name.name);

			spin_unlock(&dentry->d_lock);

			dput(dentry);

		}

		audit_log_format(ab, " dev=");

		audit_log_untrustedstring(ab, inode->i_sb->s_id);

		audit_log_format(ab, " ino=%lu", inode->i_ino);

		rcu_read_unlock();

		break;

	}

	case LSM_AUDIT_DATA_TASK: {