[patch] security: fix dummy xattr functions

[Miklos Szeredi]

Hi James,

If this (untested) patch looks OK, could you please apply it to your
tree?

Thanks,
Miklos

----
From: Miklos Szeredi <mszeredi@xxxxxxx>

Replace open coded xattr checks with cap_inode_xxx() function calls in
dummy_inode_setxattr() and dummy_inode_removexattr().  The old ones
were out of sync with the cap_inode_xxx() implementation, which could
even be a security problem.

Noticed by John Johansen.

CC: John Johansen <jjohansen@xxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
---
 security/dummy.c |   12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

Index: linux-2.6/security/dummy.c
===================================================================
--- linux-2.6.orig/security/dummy.c	2008-07-01 21:44:03.000000000 +0200
+++ linux-2.6/security/dummy.c	2008-07-01 21:51:08.000000000 +0200
@@ -370,11 +370,7 @@ static void dummy_inode_delete (struct i
 static int dummy_inode_setxattr (struct dentry *dentry, const char *name,
 				 const void *value, size_t size, int flags)
 {
-	if (!strncmp(name, XATTR_SECURITY_PREFIX,
-		     sizeof(XATTR_SECURITY_PREFIX) - 1) &&
-	    !capable(CAP_SYS_ADMIN))
-		return -EPERM;
-	return 0;
+	return cap_inode_setxattr(dentry, name, value, size, flags);
 }
 
 static void dummy_inode_post_setxattr (struct dentry *dentry, const char *name,
@@ -395,11 +391,7 @@ static int dummy_inode_listxattr (struct
 
 static int dummy_inode_removexattr (struct dentry *dentry, const char *name)
 {
-	if (!strncmp(name, XATTR_SECURITY_PREFIX,
-		     sizeof(XATTR_SECURITY_PREFIX) - 1) &&
-	    !capable(CAP_SYS_ADMIN))
-		return -EPERM;
-	return 0;
+	return cap_inode_removexattr(dentry, name);
 }
 
 static int dummy_inode_need_killpriv(struct dentry *dentry)
--
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