cifs: Use mask of ACEs for SID Everyone to calculate all three permissions user, group, and other

If a DACL has entries for ACEs for SID Everyone and Authenticated Users,
factor in mask in respective entries during calculation of permissions
for all three, user, group, and other.

http://technet.microsoft.com/en-us/library/bb463216.aspx

Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

fs/cifs/cifsacl.c

@@ -41,9 +41,12 @@ static struct cifs_wksid wksidarr[NUM_WK_SIDS] = {
 ;
 
 
-/* security id for everyone */
+/* security id for everyone/world system group */
 static const struct cifs_sid sid_everyone = {
 	1, 1, {0, 0, 0, 0, 0, 1}, {0} };
+/* security id for Authenticated Users system group */
+static const struct cifs_sid sid_authusers = {
+	1, 1, {0, 0, 0, 0, 0, 5}, {11} };
 /* group users */
 static const struct cifs_sid sid_user = {1, 2 , {0, 0, 0, 0, 0, 5}, {} };
 
@@ -365,7 +368,7 @@ static void parse_dacl(struct cifs_acl *pdacl, char *end_of_acl,
 	if (num_aces  > 0) {
 		umode_t user_mask = S_IRWXU;
 		umode_t group_mask = S_IRWXG;
-		umode_t other_mask = S_IRWXO;
+		umode_t other_mask = S_IRWXU | S_IRWXG | S_IRWXO;
 
 		ppace = kmalloc(num_aces * sizeof(struct cifs_ace *),
 				GFP_KERNEL);
@@ -390,6 +393,12 @@ static void parse_dacl(struct cifs_acl *pdacl, char *end_of_acl,
 						     ppace[i]->type,
 						     &fattr->cf_mode,
 						     &other_mask);
+			if (compare_sids(&(ppace[i]->sid), &sid_authusers))
+				access_flags_to_mode(ppace[i]->access_req,
+						     ppace[i]->type,
+						     &fattr->cf_mode,
+						     &other_mask);
+
 
 /*			memcpy((void *)(&(cifscred->aces[i])),
 				(void *)ppace[i],