From: Roberto Sassu roberto.sassu@huawei.com
Implement a simple parser of RPM headers, that extracts the digest and the algorithm of the packaged files from the RPMTAG_FILEDIGESTS and RPMTAG_FILEDIGESTALGO section, and add them to the digest cache.
The rpm digest list parser has been verified with Frama-C (https://frama-c.com/).
The analysis has been done on this file:
https://github.com/robertosassu/rpm-formal/blob/main/validate_rpm.c
Here is the result of the analysis:
[eva:summary] ====== ANALYSIS SUMMARY ====== --------------------------------------------------------------------------- 7 functions analyzed (out of 7): 100% coverage. In these functions, 228 statements reached (out of 246): 92% coverage. --------------------------------------------------------------------------- No errors or warnings raised during the analysis. --------------------------------------------------------------------------- 0 alarms generated by the analysis. --------------------------------------------------------------------------- Evaluation of the logical properties reached by the analysis: Assertions 6 valid 0 unknown 0 invalid 6 total Preconditions 29 valid 0 unknown 0 invalid 29 total 100% of the logical properties reached have been proven. ---------------------------------------------------------------------------
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- security/digest_cache/Makefile | 1 + security/digest_cache/parsers/parsers.h | 2 + security/digest_cache/parsers/rpm.c | 223 ++++++++++++++++++++++++ security/digest_cache/populate.c | 2 + 4 files changed, 228 insertions(+) create mode 100644 security/digest_cache/parsers/rpm.c
diff --git a/security/digest_cache/Makefile b/security/digest_cache/Makefile index a383b6ef2550..eca4076497e6 100644 --- a/security/digest_cache/Makefile +++ b/security/digest_cache/Makefile @@ -7,3 +7,4 @@ obj-$(CONFIG_SECURITY_DIGEST_CACHE) += digest_cache.o digest_cache-y := main.o secfs.o htable.o populate.o modsig.o
digest_cache-y += parsers/tlv.o +digest_cache-y += parsers/rpm.o diff --git a/security/digest_cache/parsers/parsers.h b/security/digest_cache/parsers/parsers.h index 1bbae426ab9f..3f00d29ed92a 100644 --- a/security/digest_cache/parsers/parsers.h +++ b/security/digest_cache/parsers/parsers.h @@ -11,3 +11,5 @@
int digest_list_parse_tlv(struct digest_cache *digest_cache, const u8 *data, size_t data_len); +int digest_list_parse_rpm(struct digest_cache *digest_cache, const u8 *data, + size_t data_len); diff --git a/security/digest_cache/parsers/rpm.c b/security/digest_cache/parsers/rpm.c new file mode 100644 index 000000000000..6c7fe9c9121c --- /dev/null +++ b/security/digest_cache/parsers/rpm.c @@ -0,0 +1,223 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2017-2024 Huawei Technologies Duesseldorf GmbH + * + * Author: Roberto Sassu roberto.sassu@huawei.com + * + * Parse an rpm digest list (RPM package header). + */ + +#define pr_fmt(fmt) "RPM DIGEST LIST: "fmt +#include <linux/module.h> + +#include "parsers.h" + +#define RPMTAG_FILEDIGESTS 1035 +#define RPMTAG_FILEDIGESTALGO 5011 + +#define RPM_INT32_TYPE 4 +#define RPM_STRING_ARRAY_TYPE 8 + +struct rpm_hdr { + u32 magic; + u32 reserved; + u32 tags; + u32 datasize; +} __packed; + +struct rpm_entryinfo { + s32 tag; + u32 type; + s32 offset; + u32 count; +} __packed; + +enum pgp_algos { + DIGEST_ALGO_MD5 = 1, + DIGEST_ALGO_SHA1 = 2, + DIGEST_ALGO_RMD160 = 3, + /* 4, 5, 6, and 7 are reserved. */ + DIGEST_ALGO_SHA256 = 8, + DIGEST_ALGO_SHA384 = 9, + DIGEST_ALGO_SHA512 = 10, + DIGEST_ALGO_SHA224 = 11, +}; + +static const enum hash_algo pgp_algo_mapping[DIGEST_ALGO_SHA224 + 1] = { + [DIGEST_ALGO_MD5] = HASH_ALGO_MD5, + [DIGEST_ALGO_SHA1] = HASH_ALGO_SHA1, + [DIGEST_ALGO_RMD160] = HASH_ALGO_RIPE_MD_160, + [4] = HASH_ALGO__LAST, + [5] = HASH_ALGO__LAST, + [6] = HASH_ALGO__LAST, + [7] = HASH_ALGO__LAST, + [DIGEST_ALGO_SHA256] = HASH_ALGO_SHA256, + [DIGEST_ALGO_SHA384] = HASH_ALGO_SHA384, + [DIGEST_ALGO_SHA512] = HASH_ALGO_SHA512, + [DIGEST_ALGO_SHA224] = HASH_ALGO_SHA224, +}; + +/** + * digest_list_parse_rpm - Parse an rpm digest list + * @digest_cache: Digest cache + * @data: Data to parse + * @data_len: Length of @data + * + * This function parses an rpm digest list. + * + * Return: Zero on success, a POSIX error code otherwise. + */ +int digest_list_parse_rpm(struct digest_cache *digest_cache, const u8 *data, + size_t data_len) +{ + const unsigned char rpm_header_magic[8] = { + 0x8e, 0xad, 0xe8, 0x01, 0x00, 0x00, 0x00, 0x00 + }; + const struct rpm_hdr *hdr; + const struct rpm_entryinfo *entry; + u32 tags, max_tags, datasize; + u32 digests_count, max_digests_count; + u32 digests_offset, algo_offset; + u32 digest_len, pkg_pgp_algo, i; + bool algo_offset_set = false, digests_offset_set = false; + enum hash_algo pkg_kernel_algo = HASH_ALGO_MD5; + u8 rpm_digest[SHA512_DIGEST_SIZE]; + int ret; + + if (data_len < sizeof(*hdr)) { + pr_debug("Not enough data for RPM header, current %ld, expected: %ld\n", + data_len, sizeof(*hdr)); + return -EINVAL; + } + + if (memcmp(data, rpm_header_magic, sizeof(rpm_header_magic))) { + pr_debug("RPM header magic mismatch\n"); + return -EINVAL; + } + + hdr = (const struct rpm_hdr *)data; + data += sizeof(*hdr); + data_len -= sizeof(*hdr); + + tags = __be32_to_cpu(hdr->tags); + max_tags = data_len / sizeof(*entry); + + /* Finite termination on tags loop. */ + if (tags > max_tags) + return -EINVAL; + + datasize = __be32_to_cpu(hdr->datasize); + if (datasize != data_len - tags * sizeof(*entry)) + return -EINVAL; + + pr_debug("Scanning %d RPM header sections\n", tags); + for (i = 0; i < tags; i++) { + if (data_len < sizeof(*entry)) + return -EINVAL; + + entry = (const struct rpm_entryinfo *)data; + data += sizeof(*entry); + data_len -= sizeof(*entry); + + switch (__be32_to_cpu(entry->tag)) { + case RPMTAG_FILEDIGESTS: + if (__be32_to_cpu(entry->type) != RPM_STRING_ARRAY_TYPE) + return -EINVAL; + + digests_offset = __be32_to_cpu(entry->offset); + digests_count = __be32_to_cpu(entry->count); + digests_offset_set = true; + + pr_debug("Found RPMTAG_FILEDIGESTS at offset %u, count: %u\n", + digests_offset, digests_count); + break; + case RPMTAG_FILEDIGESTALGO: + if (__be32_to_cpu(entry->type) != RPM_INT32_TYPE) + return -EINVAL; + + algo_offset = __be32_to_cpu(entry->offset); + algo_offset_set = true; + + pr_debug("Found RPMTAG_FILEDIGESTALGO at offset %u\n", + algo_offset); + break; + default: + break; + } + } + + if (!digests_offset_set) + return 0; + + if (algo_offset_set) { + if (algo_offset >= data_len) + return -EINVAL; + + if (data_len - algo_offset < sizeof(u32)) + return -EINVAL; + + pkg_pgp_algo = *(u32 *)&data[algo_offset]; + pkg_pgp_algo = __be32_to_cpu(pkg_pgp_algo); + if (pkg_pgp_algo > DIGEST_ALGO_SHA224) { + pr_debug("Unknown PGP algo %d\n", pkg_pgp_algo); + return -EINVAL; + } + + pkg_kernel_algo = pgp_algo_mapping[pkg_pgp_algo]; + if (pkg_kernel_algo >= HASH_ALGO__LAST) { + pr_debug("Unknown mapping for PGP algo %d\n", + pkg_pgp_algo); + return -EINVAL; + } + + pr_debug("Found mapping for PGP algo %d: %s\n", pkg_pgp_algo, + hash_algo_name[pkg_kernel_algo]); + } + + digest_len = hash_digest_size[pkg_kernel_algo]; + + if (digests_offset > data_len) + return -EINVAL; + + /* Worst case, every digest is a \0. */ + max_digests_count = data_len - digests_offset; + + /* Finite termination on digests_count loop. */ + if (digests_count > max_digests_count) + return -EINVAL; + + ret = digest_cache_htable_init(digest_cache, digests_count, + pkg_kernel_algo); + if (ret < 0) + return ret; + + for (i = 0; i < digests_count; i++) { + if (digests_offset == data_len) + return -EINVAL; + + if (!data[digests_offset]) { + digests_offset++; + continue; + } + + if (data_len - digests_offset < digest_len * 2 + 1) + return -EINVAL; + + ret = hex2bin(rpm_digest, (const char *)&data[digests_offset], + digest_len); + if (ret < 0) { + pr_debug("Invalid hex format for digest %s\n", + &data[digests_offset]); + return -EINVAL; + } + + ret = digest_cache_htable_add(digest_cache, rpm_digest, + pkg_kernel_algo); + if (ret < 0) + return ret; + + digests_offset += digest_len * 2 + 1; + } + + return ret; +} diff --git a/security/digest_cache/populate.c b/security/digest_cache/populate.c index 13645ec4bb2b..1770c8385017 100644 --- a/security/digest_cache/populate.c +++ b/security/digest_cache/populate.c @@ -68,6 +68,8 @@ static int digest_cache_parse_digest_list(struct digest_cache *digest_cache,
if (!strncmp(format, "tlv-", 4)) ret = digest_list_parse_tlv(digest_cache, data, data_len); + else if (!strncmp(format, "rpm-", 4)) + ret = digest_list_parse_rpm(digest_cache, data, data_len);
return ret; }