w1: don't allow arbitrary users to remove w1 devices

The search/pullup/add/remove device attributes were 0666 which would allow
arbitrary users to affect the 1 wire bus. Change to 0664 to prevent that.

I found this patch in the Android tree, apparently this has never been
sent upstream so doing it now.

Signed-off-by: Brian Swetland <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>
Cc: Evgeniy Polyakov <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/w1/w1.c

···
 static W1_MASTER_ATTR_RO(attempts, S_IRUGO);
 static W1_MASTER_ATTR_RO(timeout, S_IRUGO);
 static W1_MASTER_ATTR_RO(pointer, S_IRUGO);
-static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUGO);
-static W1_MASTER_ATTR_RW(pullup, S_IRUGO | S_IWUGO);
-static W1_MASTER_ATTR_RW(add, S_IRUGO | S_IWUGO);
-static W1_MASTER_ATTR_RW(remove, S_IRUGO | S_IWUGO);
+static W1_MASTER_ATTR_RW(search, S_IRUGO | S_IWUSR | S_IWGRP);
+static W1_MASTER_ATTR_RW(pullup, S_IRUGO | S_IWUSR | S_IWGRP);
+static W1_MASTER_ATTR_RW(add, S_IRUGO | S_IWUSR | S_IWGRP);
+static W1_MASTER_ATTR_RW(remove, S_IRUGO | S_IWUSR | S_IWGRP);
 
 static struct attribute *w1_master_default_attrs[] = {
 	&w1_master_attribute_name.attr,