audit: replace getname()/putname() hacks with reference counters

In order to ensure that filenames are not released before the audit
subsystem is done with the strings there are a number of hacks built
into the fs and audit subsystems around getname() and putname().  To
say these hacks are "ugly" would be kind.

This patch removes the filename hackery in favor of a more
conventional reference count based approach.  The diffstat below tells
most of the story; lots of audit/fs specific code is replaced with a
traditional reference count based approach that is easily understood,
even by those not familiar with the audit and/or fs subsystems.

CC: viro@zeniv.linux.org.uk
CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 2 insertions, 7 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index f90c0282c114..b49842fe203f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2080,6 +2080,7 @@ struct filename {
         const char              *name;  /* pointer to actual string */
         const __user char       *uptr;  /* original userland pointer */
         struct audit_names      *aname;
+        int                     refcnt;
         bool                    separate; /* should "name" be freed? */
 };
 
@@ -2101,6 +2102,7 @@ extern int filp_close(struct file *, fl_owner_t id);
 extern struct filename *getname_flags(const char __user *, int, int *);
 extern struct filename *getname(const char __user *);
 extern struct filename *getname_kernel(const char *);
+extern void putname(struct filename *name);
 
 enum {
         FILE_CREATED = 1,
@@ -2121,15 +2123,8 @@ extern void __init vfs_caches_init(unsigned long);
 
 extern struct kmem_cache *names_cachep;
 
-extern void final_putname(struct filename *name);
-
 #define __getname()             kmem_cache_alloc(names_cachep, GFP_KERNEL)
 #define __putname(name)         kmem_cache_free(names_cachep, (void *)(name))
-#ifndef CONFIG_AUDITSYSCALL
-#define putname(name)           final_putname(name)
-#else
-extern void putname(struct filename *name);
-#endif
 
 #ifdef CONFIG_BLOCK
 extern int register_blkdev(unsigned int, const char *);