smackfs: do not trust `count' in inodes write()s

Smackfs write() implementation does not put a higher bound on the number of
bytes to copy from user-space.  This may lead to a DOS attack if a malicious
`count' field is given.

Assure that given `count' is exactly the length needed for a /smack/load rule.
 In case of /smack/cipso where the length is relative, assure that `count'
does not exceed the size needed for a buffer representing maximum possible
number of CIPSO 2.2 categories.

Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 8 deletions

diff --git a/security/smack/smack.h b/security/smack/smack.h
index a21a0e907ab3..62c1e982849d 100644
--- a/security/smack/smack.h
+++ b/security/smack/smack.h
@@ -26,14 +26,6 @@
 #define SMK_MAXLEN      23
 #define SMK_LABELLEN    (SMK_MAXLEN+1)
 
-/*
- * How many kinds of access are there?
- * Here's your answer.
- */
-#define SMK_ACCESSDASH  '-'
-#define SMK_ACCESSLOW   "rwxa"
-#define SMK_ACCESSKINDS (sizeof(SMK_ACCESSLOW) - 1)
-
 struct superblock_smack {
         char            *smk_root;
         char            *smk_floor;