Revert "selinux: consider filesystem subtype in policies"

This reverts commit 102aefdda4d8275ce7d7100bc16c88c74272b260.

Tom London reports that it causes sync() to hang on Fedora rawhide:

  https://bugzilla.redhat.com/show_bug.cgi?id=1033965

and Josh Boyer bisected it down to this commit.  Reverting the commit in
the rawhide kernel fixes the problem.

Eric Paris root-caused it to incorrect subtype matching in that commit
breaking fuse, and has a tentative patch, but by now we're better off
retrying this in 3.14 rather than playing with it any more.

Reported-by: Tom London <selinux@gmail.com>
Bisected-by: Josh Boyer <jwboyer@fedoraproject.org>
Acked-by: Eric Paris <eparis@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: Anand Avati <avati@redhat.com>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 38 deletions

diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index ee470a0b5c27..d106733ad987 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -2334,50 +2334,16 @@ int security_fs_use(struct super_block *sb)
 	struct ocontext *c;
 	struct superblock_security_struct *sbsec = sb->s_security;
 	const char *fstype = sb->s_type->name;
-	const char *subtype = (sb->s_subtype && sb->s_subtype[0]) ? sb->s_subtype : NULL;
-	struct ocontext *base = NULL;
 
 	read_lock(&policy_rwlock);
 
-	for (c = policydb.ocontexts[OCON_FSUSE]; c; c = c->next) {
-		char *sub;
-		int baselen;
-
-		baselen = strlen(fstype);
-
-		/* if base does not match, this is not the one */
-		if (strncmp(fstype, c->u.name, baselen))
-			continue;
-
-		/* if there is no subtype, this is the one! */
-		if (!subtype)
-			break;
-
-		/* skip past the base in this entry */
-		sub = c->u.name + baselen;
-
-		/* entry is only a base. save it. keep looking for subtype */
-		if (sub[0] == '\0') {
-			base = c;
-			continue;
-		}
-
-		/* entry is not followed by a subtype, so it is not a match */
-		if (sub[0] != '.')
-			continue;
-
-		/* whew, we found a subtype of this fstype */
-		sub++; /* move past '.' */
-
-		/* exact match of fstype AND subtype */
-		if (!strcmp(subtype, sub))
+	c = policydb.ocontexts[OCON_FSUSE];
+	while (c) {
+		if (strcmp(fstype, c->u.name) == 0)
 			break;
+		c = c->next;
 	}
 
-	/* in case we had found an fstype match but no subtype match */
-	if (!c)
-		c = base;
-
 	if (c) {
 		sbsec->behavior = c->v.behavior;
 		if (!c->sid[0]) {