selinux: add security in-core xattr support for pstore and debugfs

- add "pstore" and "debugfs" to list of in-core exceptions
- change fstype checks to boolean equation
- change from strncmp to strcmp for checking
Signed-off-by: NMark Salyzyn <salyzyn@android.com>
Acked-by: NStephen Smalley <sds@tycho.nsa.gov>
[PM: tweaked the subject line prefix to "selinux"]
Signed-off-by: NPaul Moore <pmoore@redhat.com>

security/selinux/hooks.c

@@ -401,23 +401,14 @@ static int selinux_is_sblabel_mnt(struct super_block *sb)
 {
 	struct superblock_security_struct *sbsec = sb->s_security;
 
-	if (sbsec->behavior == SECURITY_FS_USE_XATTR ||
+	return sbsec->behavior == SECURITY_FS_USE_XATTR ||
 		sbsec->behavior == SECURITY_FS_USE_TRANS ||
-	    sbsec->behavior == SECURITY_FS_USE_TASK)
-		return 1;
-
-	/* Special handling for sysfs. Is genfs but also has setxattr handler*/
-	if (strncmp(sb->s_type->name, "sysfs", sizeof("sysfs")) == 0)
-		return 1;
-
-	/*
-	 * Special handling for rootfs. Is genfs but supports
-	 * setting SELinux context on in-core inodes.
-	 */
-	if (strncmp(sb->s_type->name, "rootfs", sizeof("rootfs")) == 0)
-		return 1;
-
-	return 0;
+		sbsec->behavior == SECURITY_FS_USE_TASK ||
+		/* Special handling. Genfs but also in-core setxattr handler */
+		!strcmp(sb->s_type->name, "sysfs") ||
+		!strcmp(sb->s_type->name, "pstore") ||
+		!strcmp(sb->s_type->name, "debugfs") ||
+		!strcmp(sb->s_type->name, "rootfs");
 }
 
 static int sb_finish_set_opts(struct super_block *sb)