This patch introduces the necessary functions to parse a digest list and to execute the requested operation.
The main function is digest_list_parse(), which coordinates the various steps required to add or delete a digest list, and has the logic to roll back when one of the steps fails.
A more detailed description about the steps can be found in Documentation/security/digest_lists.rst
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- Documentation/security/digest_lists.rst | 33 +++ MAINTAINERS | 1 + security/integrity/digest_lists/Makefile | 2 +- .../integrity/digest_lists/digest_lists.h | 3 + security/integrity/digest_lists/parser.c | 270 ++++++++++++++++++ 5 files changed, 308 insertions(+), 1 deletion(-) create mode 100644 security/integrity/digest_lists/parser.c
diff --git a/Documentation/security/digest_lists.rst b/Documentation/security/digest_lists.rst index 8f1d15a37dbd..04ea4b3790e0 100644 --- a/Documentation/security/digest_lists.rst +++ b/Documentation/security/digest_lists.rst @@ -611,3 +611,36 @@ hash table for the ``COMPACT_DIGEST_LIST`` type. Deletion can be done only if the digest list is found. ``digest_list_del()`` then deletes the ``digest_list_item``, the special ``digest_list_item_ref`` and the ``digest_item``. + + +Parser +------ + +This section introduces the necessary functions to parse a digest list and +to execute the requested operation. + +The main function is ``digest_list_parse()``, which coordinates the +various steps required to add or delete a digest list, and has the logic +to roll back when one of the steps fails. + +#. Calls ``digest_list_validate()`` to validate the passed buffer + containing the digest list to ensure that the format is correct. + +#. Calls ``get_digest_list()`` to create a new ``digest_list_item`` for the + add operation, or to retrieve the existing one for the delete operation. + ``get_digest_list()`` refuses to add digest lists that were previously + added and to delete digest lists that weren't previously added. Also, + ``get_digest_list()`` refuses to delete digest lists that are not + processed in the same way as when they were added (it would guarantee + that also deletion is notified to remote verifiers). + +#. Calls ``_digest_list_parse()`` which takes the created/retrieved + ``digest_list_item`` and adds or delete the digests included in the + digest list. + +#. If an error occurred, performs a rollback to the previous state, by + calling ``_digest_list_parse()`` with the opposite operation and the + buffer size at the time the error occurred. + +#. ``digest_list_parse()`` deletes the ``digest_list_item`` on unsuccessful + add or successful delete. diff --git a/MAINTAINERS b/MAINTAINERS index a9eb52e65b12..31d280acf5fb 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8390,6 +8390,7 @@ F: Documentation/security/digest_lists.rst F: include/linux/digest_list.h F: security/integrity/digest_lists/digest_list.h F: security/integrity/digest_lists/methods.c +F: security/integrity/digest_lists/parser.c F: uapi/linux/digest_lists.h
HUAWEI ETHERNET DRIVER diff --git a/security/integrity/digest_lists/Makefile b/security/integrity/digest_lists/Makefile index 0ba66ab2e260..86cca5bb7824 100644 --- a/security/integrity/digest_lists/Makefile +++ b/security/integrity/digest_lists/Makefile @@ -5,4 +5,4 @@
obj-$(CONFIG_DIGEST_LISTS) += digest_lists.o
-digest_lists-y := methods.o +digest_lists-y := methods.o parser.o diff --git a/security/integrity/digest_lists/digest_lists.h b/security/integrity/digest_lists/digest_lists.h index aadce9ca8f5f..442ab116a6a5 100644 --- a/security/integrity/digest_lists/digest_lists.h +++ b/security/integrity/digest_lists/digest_lists.h @@ -148,4 +148,7 @@ struct digest_item *digest_list_add(u8 *digest, enum hash_algo algo, const char *label); struct digest_item *digest_list_del(u8 *digest, enum hash_algo algo, u8 actions, struct digest_list_item *digest_list); + +int digest_list_parse(loff_t size, void *buf, enum ops op, u8 actions, + u8 *digest, enum hash_algo algo, const char *label); #endif /*__DIGEST_LISTS_INTERNAL_H*/ diff --git a/security/integrity/digest_lists/parser.c b/security/integrity/digest_lists/parser.c new file mode 100644 index 000000000000..7ed6765a9dc4 --- /dev/null +++ b/security/integrity/digest_lists/parser.c @@ -0,0 +1,270 @@ +// 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: parser.c + * Functions to parse digest lists. + */ + +#include <linux/vmalloc.h> +#include <linux/module.h> + +#include "digest_lists.h" +#include "../integrity.h" + +/** + * digest_list_validate - validate format of digest list + * @size: buffer size + * @buf: buffer containing the digest list + * + * This function validates the format of the passed digest list. + * + * Returns 0 if the digest list was successfully validated, -EINVAL otherwise. + */ +static int digest_list_validate(loff_t size, void *buf) +{ + void *bufp = buf, *bufendp = buf + size; + struct compact_list_hdr *hdr; + size_t digest_len; + + while (bufp < bufendp) { + if (bufp + sizeof(*hdr) > bufendp) { + pr_err("invalid data\n"); + return -EINVAL; + } + + hdr = bufp; + + if (hdr->version != 1) { + pr_err("unsupported version\n"); + return -EINVAL; + } + + hdr->type = le16_to_cpu(hdr->type); + hdr->modifiers = le16_to_cpu(hdr->modifiers); + hdr->algo = le16_to_cpu(hdr->algo); + hdr->count = le32_to_cpu(hdr->count); + hdr->datalen = le32_to_cpu(hdr->datalen); + + if (hdr->algo >= HASH_ALGO__LAST) { + pr_err("invalid hash algorithm\n"); + return -EINVAL; + } + + digest_len = hash_digest_size[hdr->algo]; + + if (hdr->type >= COMPACT__LAST || + hdr->type == COMPACT_DIGEST_LIST) { + pr_err("invalid type %d\n", hdr->type); + return -EINVAL; + } + + bufp += sizeof(*hdr); + + if (hdr->datalen != hdr->count * digest_len || + bufp + hdr->datalen > bufendp) { + pr_err("invalid data\n"); + return -EINVAL; + } + + bufp += hdr->count * digest_len; + } + + return 0; +} + +/** + * _digest_list_parse - parse digest list and add/delete digests + * @size: buffer size + * @buf: buffer containing the digest list + * @op: operation to be performed + * @digest_list: digest list digests being added/deleted belong to + * + * This function parses the digest list and adds or delete the digests in the + * found digest blocks. + * + * Returns the buffer size if all digests were successfully added or deleted, + * the size of the already parsed buffer on error. + */ +static int _digest_list_parse(loff_t size, void *buf, enum ops op, + struct digest_list_item *digest_list) +{ + void *bufp = buf, *bufendp = buf + size; + struct compact_list_hdr *hdr; + struct digest_item *d; + size_t digest_len; + int i; + + while (bufp < bufendp) { + if (bufp + sizeof(*hdr) > bufendp) + break; + + hdr = bufp; + bufp += sizeof(*hdr); + + digest_len = hash_digest_size[hdr->algo]; + + for (i = 0; i < hdr->count && bufp + digest_len <= bufendp; + i++, bufp += digest_len) { + switch (op) { + case DIGEST_LIST_ADD: + d = digest_add(bufp, hdr->algo, hdr->type, + digest_list, bufp - buf, + (void *)hdr - buf); + break; + case DIGEST_LIST_DEL: + d = digest_del(bufp, hdr->algo, hdr->type, + digest_list, bufp - buf, + (void *)hdr - buf); + break; + default: + break; + } + + if (IS_ERR(d)) { + pr_err("failed to %s a digest from %s\n", + (op == DIGEST_LIST_ADD) ? + "add" : "delete", digest_list->label); + goto out; + } + } + } +out: + return bufp - buf; +} + +/** + * get_digest_list - get the digest list extracted digests will be associated to + * @size: buffer size + * @buf: buffer containing the digest list + * @op: digest list operation + * @actions: actions performed on the digest list being processed + * @digest: digest of the digest list + * @algo: digest algorithm + * @label: label to identify the digest list (e.g. file name) + * + * This function retrieves the digest list item for the passed digest and + * algorithm. If it is not found at addition time, this function creates a new + * one. + * + * This function also ensures that the actions done at the time of deletion + * match the actions done at the time of addition (it would guarantee that also + * deletion is notified to remote verifiers). + * + * Returns the retrieved/created digest list item on success, an error pointer + * otherwise. + */ +static struct digest_list_item *get_digest_list(loff_t size, void *buf, + enum ops op, u8 actions, + u8 *digest, enum hash_algo algo, + const char *label) +{ + struct digest_item *d; + struct digest_list_item *digest_list; + int digest_len = hash_digest_size[algo]; + + switch (op) { + case DIGEST_LIST_ADD: + /* Add digest list to be associated to each digest. */ + d = digest_list_add(digest, algo, size, buf, actions, label); + if (IS_ERR(d)) + return (void *)d; + + digest_list = d->refs[0].digest_list; + break; + case DIGEST_LIST_DEL: + /* Lookup digest list to delete the references. */ + d = digest_lookup(digest, algo, COMPACT_DIGEST_LIST, NULL, + NULL); + if (!d) { + print_hex_dump(KERN_ERR, + "digest list digest not found: ", + DUMP_PREFIX_NONE, digest_len, 1, digest, + digest_len, true); + return ERR_PTR(-ENOENT); + } + + digest_list = d->refs[0].digest_list; + + /* Reject deletion if actions on delete differ from add. */ + if (digest_list->actions != actions) { + pr_err("actions mismatch, add: %d, del: %d\n", + digest_list->actions, actions); + return ERR_PTR(-EPERM); + } + + break; + default: + return ERR_PTR(-EINVAL); + } + + return digest_list; +} + +/** + * digest_list_parse - parse a digest list + * @size: buffer size + * @buf: buffer containing the digest list + * @op: digest list operation + * @actions: actions performed on the digest list being processed + * @digest: digest of the digest list + * @algo: digest algorithm + * @label: label to identify the digest list (e.g. file name) + * + * This function parses the passed digest list and executed the requested + * operation. If the operation cannot be successfully executed, this function + * performs a rollback to the previous state. + * + * Returns the buffer size on success, a negative value otherwise. + */ +int digest_list_parse(loff_t size, void *buf, enum ops op, u8 actions, + u8 *digest, enum hash_algo algo, const char *label) +{ + struct digest_item *d; + struct digest_list_item *digest_list; + enum ops rollback_op = (op == DIGEST_LIST_ADD) ? + DIGEST_LIST_DEL : DIGEST_LIST_ADD; + int ret, rollback_size; + + ret = digest_list_validate(size, buf); + if (ret < 0) + return ret; + + digest_list = get_digest_list(size, buf, op, actions, digest, algo, + label); + if (IS_ERR(digest_list)) + return PTR_ERR(digest_list); + + ret = _digest_list_parse(size, buf, op, digest_list); + if (ret < 0) + goto out; + + if (ret != size) { + rollback_size = ret; + + ret = _digest_list_parse(rollback_size, buf, rollback_op, + digest_list); + if (ret != rollback_size) + pr_err("rollback failed\n"); + + ret = -EINVAL; + } +out: + /* Delete digest list on unsuccessful add or successful delete. */ + if ((op == DIGEST_LIST_ADD && ret < 0) || + (op == DIGEST_LIST_DEL && ret == size)) { + d = digest_list_del(digest, algo, actions, digest_list); + if (IS_ERR(d)) + return PTR_ERR(d); + } + + return ret; +}