linux-kernel - [PATCH] Smack: check for SMACK xattr max size in smack_inode

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Date:	Tue, 14 Apr 2009 20:28:06 +0200
From:	Etienne Basset <etienne.basset@...ericable.fr>
To:	Casey Schaufler <casey@...aufler-ca.com>,
	LSM <linux-security-module@...r.kernel.org>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH] Smack: check for SMACK xattr max size in  smack_inode_setxattr

the following patch move the check for SMACK xattr size >= SMK_LABELLEN
from  smack_inode_post_setxattr (which cannot return an error to the user)
to smack_inode_setxattr (which can return an error).

without patch a SMACK setxattr with size >= SMK_LABELLEN returns success although it doesn't 

Signed-off-by: Etienne Basset <etienne.basset@...ericable.fr>
---
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 9215149..da6954d 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -610,7 +610,8 @@ static int smack_inode_setxattr(struct dentry *dentry, const char *name,
 		if (!capable(CAP_MAC_ADMIN))
 			rc = -EPERM;
 		/* a label cannot be void and cannot begin with '-' */
-		if (size == 0 || (size > 0 && ((char *)value)[0] == '-'))
+		if (size == 0 || size >= SMK_LABELLEN ||
+		   (size > 0 && ((char *)value)[0] == '-'))
 			rc = -EINVAL;
 	} else
 		rc = cap_inode_setxattr(dentry, name, value, size, flags);
@@ -644,9 +645,6 @@ static void smack_inode_post_setxattr(struct dentry *dentry, const char *name,
 	if (strcmp(name, XATTR_NAME_SMACK))
 		return;
 
-	if (size >= SMK_LABELLEN)
-		return;
-
 	isp = dentry->d_inode->i_security;
 
 	/*

--
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