From: Greg KH [mailto:gregkh@linuxfoundation.org] Sent: Sunday, June 27, 2021 12:56 PM On Fri, Jun 25, 2021 at 06:56:06PM +0200, Roberto Sassu wrote:
+++ b/security/integrity/digest_lists/digest_lists.h @@ -0,0 +1,117 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/*
- Copyright (C) 2005,2006,2007,2008 IBM Corporation
- Copyright (C) 2017-2021 Huawei Technologies Duesseldorf GmbH
- Author: Roberto Sassu roberto.sassu@huawei.com
- This program is free software; you can redistribute it and/or
- modify it under the terms of the GNU General Public License as
- published by the Free Software Foundation, version 2 of the
- License.
- File: digest_lists.h
Unexported definitions for digest lists.Unexported to whom?
Hi Greg
I meant not placed in include/linux.
- */
+#ifndef __DIGEST_LISTS_INTERNAL_H +#define __DIGEST_LISTS_INTERNAL_H
+#include <linux/types.h> +#include <linux/crypto.h> +#include <linux/fs.h> +#include <linux/security.h> +#include <linux/hash.h> +#include <linux/tpm.h> +#include <linux/audit.h> +#include <crypto/hash_info.h> +#include <linux/hash_info.h> +#include <uapi/linux/digest_lists.h>
+#define MAX_DIGEST_SIZE 64 +#define HASH_BITS 10 +#define MEASURE_HTABLE_SIZE (1 << HASH_BITS)
+struct digest_list_item {
- loff_t size;
- u8 *buf;
- u8 actions;
- u8 digest[64];
- enum hash_algo algo;
- const char *label;
+};
+struct digest_list_item_ref {
- struct digest_list_item *digest_list;
- loff_t digest_offset;
- loff_t hdr_offset;
+};
+struct digest_item {
- /* hash table pointers */
- struct hlist_node hnext;
- /* digest list references (protected by RCU) */
- struct digest_list_item_ref *refs;
+};
+struct h_table {
- atomic_long_t len;
Why is this atomic? Why would that matter?
Yes, it shouldn't be. There are not concurrent updates.
- struct hlist_head queue[MEASURE_HTABLE_SIZE];
+};
+static inline unsigned int hash_key(u8 *digest) +{
- return (digest[0] | digest[1] << 8) % MEASURE_HTABLE_SIZE;
+}
Don't we have hashing functions in the kernel already?
We had a discussion before:
https://lore.kernel.org/linux-integrity/1587739544.5190.14.camel@linux.ibm.c...
It seems there is no real advantage in hashing a digest.
+static inline struct compact_list_hdr *get_hdr(
struct digest_list_item *digest_list,loff_t hdr_offset)+{
- return (struct compact_list_hdr *)(digest_list->buf + hdr_offset);
+}
pointer math feels rough, are you shure you want to do this this way?
Maybe, I could change digest_list_item_ref to:
struct digest_list_item_ref { struct digest_list_item *digest_list; u8 *digest; struct compact_list_hdr *hdr; };
where digest and hdr are calculated in the same way.
Or you have a different suggestion?
Thanks
Roberto
HUAWEI TECHNOLOGIES Duesseldorf GmbH, HRB 56063 Managing Director: Li Peng, Li Jian, Shi Yanli
thanks,
greg k-h