From 55422d0bd292f5ad143cc32cb8bb8505257274c4 Mon Sep 17 00:00:00 2001 From: Paul Moore Date: Thu, 22 Jan 2015 00:00:23 -0500 Subject: 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 Signed-off-by: Al Viro --- fs/namei.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) (limited to 'fs') diff --git a/fs/namei.c b/fs/namei.c index a3fde77d4abf..96ca11dea4a2 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -118,15 +118,6 @@ * POSIX.1 2.4: an empty pathname is invalid (ENOENT). * PATH_MAX includes the nul terminator --RR. */ -void final_putname(struct filename *name) -{ - if (name->separate) { - __putname(name->name); - kfree(name); - } else { - __putname(name); - } -} #define EMBEDDED_NAME_MAX (PATH_MAX - sizeof(struct filename)) @@ -145,6 +136,7 @@ getname_flags(const char __user *filename, int flags, int *empty) result = __getname(); if (unlikely(!result)) return ERR_PTR(-ENOMEM); + result->refcnt = 1; /* * First, try to embed the struct filename inside the names_cache @@ -179,6 +171,7 @@ recopy: } result->name = kname; result->separate = true; + result->refcnt = 1; max = PATH_MAX; goto recopy; } @@ -202,7 +195,7 @@ recopy: return result; error: - final_putname(result); + putname(result); return err; } @@ -243,19 +236,25 @@ getname_kernel(const char * filename) memcpy((char *)result->name, filename, len); result->uptr = NULL; result->aname = NULL; + result->refcnt = 1; audit_getname(result); return result; } -#ifdef CONFIG_AUDITSYSCALL void putname(struct filename *name) { - if (unlikely(!audit_dummy_context())) - return audit_putname(name); - final_putname(name); + BUG_ON(name->refcnt <= 0); + + if (--name->refcnt > 0) + return; + + if (name->separate) { + __putname(name->name); + kfree(name); + } else + __putname(name); } -#endif static int check_acl(struct inode *inode, int mask) { -- cgit v1.2.3