Merge selinux fix to support in-core xattr of debufgs

Cherry pick from https://android-review.googlesource.com/#/c/123424/1

pstore: 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: Mark Salyzyn <salyzyn@android.com>

BUG=26258202

Change-Id: I35b41660701fe63a5e8173813ac62b84474ec48f
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index d974ebb..3feec1f 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -392,23 +392,14 @@
 {
 	struct superblock_security_struct *sbsec = sb->s_security;
 
-	if (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;
+	return sbsec->behavior == SECURITY_FS_USE_XATTR ||
+		sbsec->behavior == SECURITY_FS_USE_TRANS ||
+		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)