Smack: check for SMACK xattr validity in smack_inode_setxattr

the following patch moves checks for SMACK xattr validity
from smack_inode_post_setxattr (which cannot return an error to the user)
to smack_inode_setxattr (which can return an error).

Signed-off-by: Etienne Basset <etienne.basset@numericable.fr>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <jmorris@namei.org>

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 9215149..98b3195 100644 (file)
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -609,8 +609,12 @@ static int smack_inode_setxattr(struct dentry *dentry, const char *name,
            strcmp(name, XATTR_NAME_SMACKIPOUT) == 0) {
                if (!capable(CAP_MAC_ADMIN))
                        rc = -EPERM;
-               /* a label cannot be void and cannot begin with '-' */
-               if (size == 0 || (size > 0 && ((char *)value)[0] == '-'))
+               /*
+                * check label validity here so import wont fail on
+                * post_setxattr
+                */
+               if (size == 0 || size >= SMK_LABELLEN ||
+                   smk_import(value, size) == NULL)
                        rc = -EINVAL;
        } else
                rc = cap_inode_setxattr(dentry, name, value, size, flags);
@@ -644,9 +648,6 @@ 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;
 
        /*