Allow reading tainted flag as user

The commit 34f5a39899 restricted reading
of the tainted value. The attached patch changes this back to a
write-only check and restores the read behaviour of older versions.

Signed-off-by: Bastian Blank <bastian@waldi.eu.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/sysctl.c

@@ -1676,7 +1676,7 @@ static int proc_dointvec_taint(ctl_table *table, int write, struct file *filp,
 {
 	int op;
 
-	if (!capable(CAP_SYS_ADMIN))
+	if (write && !capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
 	op = OP_OR;