SELinux: correctly detect proc filesystems of the form "proc/foo"

Map all of these proc/ filesystem types to "proc" for the policy lookup at
filesystem mount time.

Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 520f82a..8dbc54c 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -702,7 +702,7 @@
 		sbsec->proc = 1;
 
 	/* Determine the labeling behavior to use for this filesystem type. */
-	rc = security_fs_use(sb->s_type->name, &sbsec->behavior, &sbsec->sid);
+	rc = security_fs_use(sbsec->proc ? "proc" : sb->s_type->name, &sbsec->behavior, &sbsec->sid);
 	if (rc) {
 		printk(KERN_WARNING "%s: security_fs_use(%s) returned %d\n",
 		       __func__, sb->s_type->name, rc);