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Message-ID: <20210726163700.2092768-4-roberto.sassu@huawei.com>
Date: Mon, 26 Jul 2021 18:36:51 +0200
From: Roberto Sassu <roberto.sassu@...wei.com>
To: <zohar@...ux.ibm.com>, <gregkh@...uxfoundation.org>,
<mchehab+huawei@...nel.org>
CC: <linux-integrity@...r.kernel.org>,
<linux-security-module@...r.kernel.org>,
<linux-doc@...r.kernel.org>, <linux-kselftest@...r.kernel.org>,
<linux-kernel@...r.kernel.org>,
Roberto Sassu <roberto.sassu@...wei.com>
Subject: [RFC][PATCH v2 03/12] diglim: Objects
Define the objects to manage digest lists:
- digest_list_item: a digest list loaded into the kernel;
- digest_list_item_ref: a reference to a digest list;
- digest_item: a digest of a digest list.
Also define some helpers for the objects. More information can be found in
Documentation/security/diglim/implementation.rst.
Signed-off-by: Roberto Sassu <roberto.sassu@...wei.com>
---
.../security/diglim/implementation.rst | 105 ++++++++++++++
MAINTAINERS | 1 +
security/integrity/diglim/diglim.h | 134 ++++++++++++++++++
3 files changed, 240 insertions(+)
create mode 100644 security/integrity/diglim/diglim.h
diff --git a/Documentation/security/diglim/implementation.rst b/Documentation/security/diglim/implementation.rst
index 59a180b3bb3f..6002049612a1 100644
--- a/Documentation/security/diglim/implementation.rst
+++ b/Documentation/security/diglim/implementation.rst
@@ -95,3 +95,108 @@ with digest lists:
- ``DIGEST_LIST_ADD``: the digest list is being added;
- ``DIGEST_LIST_DEL``: the digest list is being deleted.
+
+
+Objects
+-------
+
+This section defines the objects to manage digest lists.
+
+.. kernel-doc:: security/integrity/diglim/diglim.h
+
+They are represented in the following class diagram:
+
+::
+
+ digest_offset,
+ hdr_offset---------------+
+ |
+ |
+ +------------------+ | +----------------------+
+ | digest_list_item |--- N:1 ---| digest_list_item_ref |
+ +------------------+ +----------------------+
+ |
+ 1:N
+ |
+ +-------------+
+ | digest_item |
+ +-------------+
+
+A ``digest_list_item`` is associated to one or multiple
+``digest_list_item_ref``, one for each digest it contains. However,
+a ``digest_list_item_ref`` is associated to only one ``digest_list_item``,
+as it represents a single location within a specific digest list.
+
+Given that a ``digest_list_item_ref`` represents a single location, it is
+associated to only one ``digest_item``. However, a ``digest_item`` can have
+multiple references (as it might appears multiple times within the same
+digest list or in different digest lists, if it is duplicated).
+
+All digest list references are stored for a given digest, so that a query
+result can include the OR of the modifiers and actions of each referenced
+digest list.
+
+The relationship between the described objects can be graphically
+represented as:
+
+::
+
+ Hash table +-------------+ +-------------+
+ PARSER +-----+ | digest_item | | digest_item |
+ FILE | key |-->| |-->...-->| |
+ METADATA +-----+ |ref0|...|refN| |ref0|...|refN|
+ +-------------+ +-------------+
+ ref0: | | refN:
+ digest_offset | +-----------------------------+ digest_offset
+ hdr_offset | | hdr_offset
+ | |
+ V V
+ +--------------------+
+ | digest_list_item |
+ | |
+ | size, buf, actions |
+ +--------------------+
+ ^
+ |
+ Hash table +-------------+ +-------------+
+ DIGEST_LIST +-----+ |ref0 | |ref0 |
+ | key |-->| |-->...-->| |
+ +-----+ | digest_item | | digest_item |
+ +-------------+ +-------------+
+
+The reference for the digest of the digest list differs from the references
+for the other digest types. ``digest_offset`` and ``hdr_offset`` are set to
+zero, so that the digest of the digest list is retrieved from the
+``digest_list_item`` structure directly (see ``get_digest()`` below).
+
+Finally, this section defines useful helpers to access a digest or the
+header the digest belongs to. For example:
+
+::
+
+ 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);
+ }
+
+the header can be obtained by summing the address of the digest list buffer
+in the ``digest_list_item`` structure with ``hdr_offset``.
+
+Similarly:
+
+::
+
+ static inline u8 *get_digest(struct digest_list_item *digest_list,
+ loff_t digest_offset, loff_t hdr_offset)
+ {
+ /* Digest list digest is stored in a different place. */
+ if (!digest_offset)
+ return digest_list->digest;
+ return digest_list->buf + digest_offset;
+ }
+
+the digest can be obtained by summing the address of the digest list buffer
+with ``digest_offset`` (except for the digest lists, where the digest is
+stored in the ``digest`` field of the ``digest_list_item`` structure).
diff --git a/MAINTAINERS b/MAINTAINERS
index f61f5239468a..f7592d41367d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5462,6 +5462,7 @@ F: Documentation/security/diglim/implementation.rst
F: Documentation/security/diglim/index.rst
F: Documentation/security/diglim/introduction.rst
F: include/uapi/linux/diglim.h
+F: security/integrity/diglim/diglim.h
DIOLAN U2C-12 I2C DRIVER
M: Guenter Roeck <linux@...ck-us.net>
diff --git a/security/integrity/diglim/diglim.h b/security/integrity/diglim/diglim.h
new file mode 100644
index 000000000000..578253d7e1d1
--- /dev/null
+++ b/security/integrity/diglim/diglim.h
@@ -0,0 +1,134 @@
+/* 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@...wei.com>
+ *
+ * Definitions only used inside DIGLIM.
+ */
+
+#ifndef __DIGLIM_INTERNAL_H
+#define __DIGLIM_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/diglim.h>
+
+#define MAX_DIGEST_SIZE 64
+#define HASH_BITS 10
+#define DIGLIM_HTABLE_SIZE (1 << HASH_BITS)
+
+/**
+ * struct digest_list_item - a digest list loaded into the kernel
+ *
+ * @size: size of the digest list buffer
+ * @buf: digest list buffer
+ * @digest: digest of the digest list
+ * @label: label used to identify the digest list (e.g. file name)
+ * @actions: actions performed on the digest list
+ * @algo: digest algorithm
+ */
+struct digest_list_item {
+ loff_t size;
+ u8 *buf;
+ u8 digest[64];
+ const char *label;
+ u8 actions;
+ enum hash_algo algo;
+};
+
+/**
+ * struct digest_list_item_ref - a reference to a digest list
+ *
+ * @list: linked list pointers
+ * @digest_list: pointer to struct digest_list_item
+ * @digest_offset: offset of the digest in the referenced digest list
+ * @hdr_offset: offset of the header the digest refers to in the digest list
+ */
+struct digest_list_item_ref {
+ struct list_head list;
+ struct digest_list_item *digest_list;
+ u32 digest_offset;
+ u32 hdr_offset;
+};
+
+/**
+ * struct digest_item - a digest of a digest list
+ *
+ * @hnext: pointers of the hash table
+ * @refs: linked list of struct digest_list_item_ref
+ */
+struct digest_item {
+ struct hlist_node hnext;
+ struct list_head refs;
+};
+
+struct h_table {
+ unsigned long len;
+ struct hlist_head queue[DIGLIM_HTABLE_SIZE];
+};
+
+static inline unsigned int hash_key(u8 *digest)
+{
+ return (digest[0] | digest[1] << 8) % DIGLIM_HTABLE_SIZE;
+}
+
+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);
+}
+
+static inline enum hash_algo get_algo(struct digest_list_item *digest_list,
+ loff_t digest_offset, loff_t hdr_offset)
+{
+ /* Digest list digest algorithm is stored in a different place. */
+ if (!digest_offset)
+ return digest_list->algo;
+
+ return get_hdr(digest_list, hdr_offset)->algo;
+}
+
+static inline u8 *get_digest(struct digest_list_item *digest_list,
+ loff_t digest_offset, loff_t hdr_offset)
+{
+ /* Digest list digest is stored in a different place. */
+ if (!digest_offset)
+ return digest_list->digest;
+
+ return digest_list->buf + digest_offset;
+}
+
+static inline struct compact_list_hdr *get_hdr_ref(
+ struct digest_list_item_ref *ref)
+{
+ return get_hdr(ref->digest_list, ref->hdr_offset);
+}
+
+static inline enum hash_algo get_algo_ref(struct digest_list_item_ref *ref)
+{
+ /* Digest list digest algorithm is stored in a different place. */
+ if (!ref->digest_offset)
+ return ref->digest_list->algo;
+
+ return get_hdr_ref(ref)->algo;
+}
+
+static inline u8 *get_digest_ref(struct digest_list_item_ref *ref)
+{
+ /* Digest list digest is stored in a different place. */
+ if (!ref->digest_offset)
+ return ref->digest_list->digest;
+
+ return ref->digest_list->buf + ref->digest_offset;
+}
+#endif /*__DIGLIM_INTERNAL_H*/
--
2.25.1
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