pstore: selinux: add security in-core xattr support for rootfs, pstor…

…e and debugfs

- add "rootfs", "pstore" and "debugfs" to list of in-core exceptions
- change fstype checks to boolean equation
- change from strncmp to strcmp for checking

(Cherry Pick from commit 2294d49)

Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 18917345
Bug: 18935184
Change-Id: Ib648f30ce4b5d6c96f11465836d6fee89bec1c72

security/selinux/hooks.c

@@ -419,8 +419,11 @@ static int sb_finish_set_opts(struct super_block *sb)
 	    sbsec->behavior > ARRAY_SIZE(labeling_behaviors))
 		sbsec->flags &= ~SE_SBLABELSUPP;
 
-	/* Special handling for sysfs. Is genfs but also has setxattr handler*/
-	if (strncmp(sb->s_type->name, "sysfs", sizeof("sysfs")) == 0)
+	/* Special handling. Is genfs but also has in-core setxattr handler*/
+	if (!strcmp(sb->s_type->name, "sysfs") ||
+	    !strcmp(sb->s_type->name, "pstore") ||
+	    !strcmp(sb->s_type->name, "debugfs") ||
+	    !strcmp(sb->s_type->name, "rootfs"))
 		sbsec->flags |= SE_SBLABELSUPP;
 
 	/* Initialize the root inode. */