FROMGIT: selinux: bpf: check SBLABEL_MNT before isec init

selinux_inode_init_security() marks the isec as initialized before
checking if mount labeling is supported (SBLABEL_MNT). This was fine
until commit 9722955b54 ("bpf: Add simple xattr support to bpffs"),
where genfscon bpffs mounts fail the SBLABEL_MNT check as expected (no
xattrs) and yet leave the isec->initialized. This breaks subsequent
calls to inode_doinit_with_dentry().

Do the SBLABEL_MNT check before the inode security is initialized.

Cc: stable@vger.kernel.org
Closes: https://lore.kernel.org/all/akWdcp6P0FkNDzBk@google.com/
Fixes: 9722955b54 ("bpf: Add simple xattr support to bpffs")
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>

Bug: 529733987
(cherry picked from commit 28254722a459938d97150d3b0712b81e06d0645e
 https://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux.git stable-7.2)
Change-Id: I291f198d144dda69f7ea0346b01d5fb48eb9abbe
Signed-off-by: Carlos Llamas <cmllamas@google.com>

security/selinux/hooks.c

@@ -2974,6 +2974,10 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
 
 	sbsec = selinux_superblock(dir->i_sb);
 
+	if (!selinux_initialized() ||
+	    !(sbsec->flags & SBLABEL_MNT))
+		return -EOPNOTSUPP;
+
 	newsid = crsec->create_sid;
 	newsclass = inode_mode_to_security_class(inode->i_mode);
 	rc = selinux_determine_inode_label(crsec, dir, qstr, newsclass, &newsid);
@@ -2988,10 +2992,6 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
 		isec->initialized = LABEL_INITIALIZED;
 	}
 
-	if (!selinux_initialized() ||
-	    !(sbsec->flags & SBLABEL_MNT))
-		return -EOPNOTSUPP;
-
 	xattr = lsm_get_xattr_slot(xattrs, xattr_count);
 	if (xattr) {
 		rc = security_sid_to_context_force(newsid,