From: Roberto Sassu roberto.sassu@huawei.com
Add digest_list_parse_tlv(), to parse TLV-formatted (Type Length Value) digest lists. Their structure is:
[header: DIGEST_LIST_FILE, num fields, total len] [field: DIGEST_LIST_ALGO, length, value] [field: DIGEST_LIST_ENTRY#1, length, value (below)] |- [header: DIGEST_LIST_ENTRY_DATA, num fields, total len] |- [DIGEST_LIST_ENTRY_DIGEST#1, length, file digest] |- [DIGEST_LIST_ENTRY_PATH#1, length, file path] [field: DIGEST_LIST_ENTRY#N, length, value (below)] |- [header: DIGEST_LIST_ENTRY_DATA, num fields, total len] |- [DIGEST_LIST_ENTRY_DIGEST#N, length, file digest] |- [DIGEST_LIST_ENTRY_PATH#N, length, file path]
DIGEST_LIST_ALGO must have a fixed length of sizeof(u64).
The data of the DIGEST_LIST_ENTRY field are itself in TLV format.
Currently defined fields are sufficient for measurement/appraisal of file data. More fields will be introduced later for file metadata.
Introduce digest_list_hdr_callback(), to accept TLV data with type DIGEST_LIST_FILE, and to get the number of TLV data entries for initializing a new digest cache hash table. Introduce digest_list_data_callback() to handle the DIGEST_LIST_FILE fields, DIGEST_LIST_ALGO and DIGEST_LIST_ENTRY, and the respective field parsers parse_digest_list_algo() and parse_digest_list_entry().
Introduce digest_list_entry_hdr_callback() to accept nested TLV data (DIGEST_LIST_ENTRY data entry) with type DIGEST_LIST_ENTRY_DATA. Introduce digest_list_entry_data_callback(), to handle the DIGEST_LIST_ENTRY_DATA fields, DIGEST_LIST_ENTRY_DIGEST and DIGEST_LIST_ENTRY_PATH, and the respective field parsers parse_digest_list_entry_digest() and parse_digest_list_entry_path().
The TLV parser itself is defined in lib/tlv_parser.c.
Both the TLV parser and the tlv digest list parser have been formally 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_tlv.c
Here is the result of the analysis:
[eva:summary] ====== ANALYSIS SUMMARY ====== --------------------------------------------------------------------------- 15 functions analyzed (out of 15): 100% coverage. In these functions, 248 statements reached (out of 266): 93% coverage. --------------------------------------------------------------------------- Some errors and warnings have been raised during the analysis: by the Eva analyzer: 0 errors 4 warnings by the Frama-C kernel: 0 errors 0 warnings --------------------------------------------------------------------------- 0 alarms generated by the analysis. --------------------------------------------------------------------------- Evaluation of the logical properties reached by the analysis: Assertions 5 valid 0 unknown 0 invalid 5 total Preconditions 23 valid 0 unknown 0 invalid 23 total 100% of the logical properties reached have been proven. ---------------------------------------------------------------------------
The warnings are:
[eva] validate_tlv.c:359: Warning: this partitioning parameter cannot be evaluated safely on all states [eva] validate_tlv.c:387: Warning: this partitioning parameter cannot be evaluated safely on all states [eva] validate_tlv.c:443: Warning: this partitioning parameter cannot be evaluated safely on all states [eva] validate_tlv.c:451: Warning: this partitioning parameter cannot be evaluated safely on all states
Signed-off-by: Roberto Sassu roberto.sassu@huawei.com --- include/uapi/linux/tlv_digest_list.h | 72 ++++ security/integrity/digest_cache/Kconfig | 1 + security/integrity/digest_cache/Makefile | 2 + .../integrity/digest_cache/parsers/parsers.h | 13 + security/integrity/digest_cache/parsers/tlv.c | 341 ++++++++++++++++++ security/integrity/digest_cache/populate.c | 4 + 6 files changed, 433 insertions(+) create mode 100644 include/uapi/linux/tlv_digest_list.h create mode 100644 security/integrity/digest_cache/parsers/parsers.h create mode 100644 security/integrity/digest_cache/parsers/tlv.c
diff --git a/include/uapi/linux/tlv_digest_list.h b/include/uapi/linux/tlv_digest_list.h new file mode 100644 index 000000000000..8c97a46901c1 --- /dev/null +++ b/include/uapi/linux/tlv_digest_list.h @@ -0,0 +1,72 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* + * Copyright (C) 2017-2024 Huawei Technologies Duesseldorf GmbH + * + * Author: Roberto Sassu roberto.sassu@huawei.com + * + * Export definitions of the tlv digest list. + */ + +#ifndef _UAPI_LINUX_TLV_DIGEST_LIST_H +#define _UAPI_LINUX_TLV_DIGEST_LIST_H + +#include <linux/types.h> + +#define FOR_EACH_DIGEST_LIST_TYPE(DIGEST_LIST_TYPE) \ + DIGEST_LIST_TYPE(DIGEST_LIST_FILE) \ + DIGEST_LIST_TYPE(DIGEST_LIST__LAST) + +#define FOR_EACH_DIGEST_LIST_FIELD(DIGEST_LIST_FIELD) \ + DIGEST_LIST_FIELD(DIGEST_LIST_ALGO) \ + DIGEST_LIST_FIELD(DIGEST_LIST_ENTRY) \ + DIGEST_LIST_FIELD(DIGEST_LIST_FIELD__LAST) + +#define FOR_EACH_DIGEST_LIST_ENTRY_TYPE(DIGEST_LIST_ENTRY_TYPE) \ + DIGEST_LIST_ENTRY_TYPE(DIGEST_LIST_ENTRY_DATA) \ + DIGEST_LIST_ENTRY_TYPE(DIGEST_LIST_ENTRY__LAST) + +#define FOR_EACH_DIGEST_LIST_ENTRY_FIELD(DIGEST_LIST_ENTRY_FIELD) \ + DIGEST_LIST_ENTRY_FIELD(DIGEST_LIST_ENTRY_DIGEST) \ + DIGEST_LIST_ENTRY_FIELD(DIGEST_LIST_ENTRY_PATH) \ + DIGEST_LIST_ENTRY_FIELD(DIGEST_LIST_ENTRY_FIELD__LAST) + +#define GENERATE_ENUM(ENUM) ENUM, +#define GENERATE_STRING(STRING) #STRING, + +/** + * enum digest_list_types - Types of digest list + * + * Enumerates the types of digest list to parse. + */ +enum digest_list_types { + FOR_EACH_DIGEST_LIST_TYPE(GENERATE_ENUM) +}; + +/** + * enum digest_list_fields - Digest list fields + * + * Enumerates the digest list fields. + */ +enum digest_list_fields { + FOR_EACH_DIGEST_LIST_FIELD(GENERATE_ENUM) +}; + +/** + * enum digest_list_entry_types - Types of data stored in DIGEST_LIST_ENTRY + * + * Enumerates the types of data stored in DIGEST_LIST_ENTRY (nested TLV data). + */ +enum digest_list_entry_types { + FOR_EACH_DIGEST_LIST_ENTRY_TYPE(GENERATE_ENUM) +}; + +/** + * enum digest_list_entry_fields - DIGEST_LIST_ENTRY fields + * + * Enumerates the DIGEST_LIST_ENTRY fields. + */ +enum digest_list_entry_fields { + FOR_EACH_DIGEST_LIST_ENTRY_FIELD(GENERATE_ENUM) +}; + +#endif /* _UAPI_LINUX_TLV_DIGEST_LIST_H */ diff --git a/security/integrity/digest_cache/Kconfig b/security/integrity/digest_cache/Kconfig index 11097464540a..a1c0d0337d70 100644 --- a/security/integrity/digest_cache/Kconfig +++ b/security/integrity/digest_cache/Kconfig @@ -1,6 +1,7 @@ # SPDX-License-Identifier: GPL-2.0 config INTEGRITY_DIGEST_CACHE bool "Integrity Digest Cache" + select TLV_PARSER default n help This option enables a cache of reference digests (e.g. of file diff --git a/security/integrity/digest_cache/Makefile b/security/integrity/digest_cache/Makefile index 1b91f9fba51c..5cf75c961e26 100644 --- a/security/integrity/digest_cache/Makefile +++ b/security/integrity/digest_cache/Makefile @@ -5,3 +5,5 @@ obj-$(CONFIG_INTEGRITY_DIGEST_CACHE) += digest_cache.o
digest_cache-y := main.o secfs.o htable.o populate.o modsig.o + +digest_cache-y += parsers/tlv.o diff --git a/security/integrity/digest_cache/parsers/parsers.h b/security/integrity/digest_cache/parsers/parsers.h new file mode 100644 index 000000000000..1bbae426ab9f --- /dev/null +++ b/security/integrity/digest_cache/parsers/parsers.h @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH + * + * Author: Roberto Sassu roberto.sassu@huawei.com + * + * Digest list parsers. + */ + +#include "../internal.h" + +int digest_list_parse_tlv(struct digest_cache *digest_cache, const u8 *data, + size_t data_len); diff --git a/security/integrity/digest_cache/parsers/tlv.c b/security/integrity/digest_cache/parsers/tlv.c new file mode 100644 index 000000000000..1c8cce92aded --- /dev/null +++ b/security/integrity/digest_cache/parsers/tlv.c @@ -0,0 +1,341 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2017-2024 Huawei Technologies Duesseldorf GmbH + * + * Author: Roberto Sassu roberto.sassu@huawei.com + * + * Parse a tlv digest list. + */ + +#define pr_fmt(fmt) "digest_cache TLV PARSER: "fmt +#include <linux/tlv_parser.h> +#include <uapi/linux/tlv_digest_list.h> + +#include "parsers.h" + +#define kenter(FMT, ...) \ + pr_debug("==> %s(" FMT ")\n", __func__, ##__VA_ARGS__) +#define kleave(FMT, ...) \ + pr_debug("<== %s()" FMT "\n", __func__, ##__VA_ARGS__) + +static const char *digest_list_types_str[] = { + FOR_EACH_DIGEST_LIST_TYPE(GENERATE_STRING) +}; + +static const char *digest_list_fields_str[] = { + FOR_EACH_DIGEST_LIST_FIELD(GENERATE_STRING) +}; + +static const char *digest_list_entry_types_str[] = { + FOR_EACH_DIGEST_LIST_ENTRY_TYPE(GENERATE_STRING) +}; + +static const char *digest_list_entry_fields_str[] = { + FOR_EACH_DIGEST_LIST_ENTRY_FIELD(GENERATE_STRING) +}; + +struct tlv_callback_data { + struct digest_cache *digest_cache; + u64 parsed_num_entries; + enum hash_algo algo; +}; + +/** + * parse_digest_list_entry_digest - Parse DIGEST_LIST_ENTRY_DIGEST field + * @tlv_data: Callback data + * @field: Field identifier + * @field_data: Field data + * @field_data_len: Length of @field_data + * + * This function parses the DIGEST_LIST_ENTRY_DIGEST field (file digest). + * + * Return: Zero on success, a POSIX error code otherwise. + */ +static int parse_digest_list_entry_digest(struct tlv_callback_data *tlv_data, + enum digest_list_entry_fields field, + const u8 *field_data, + u64 field_data_len) +{ + int ret; + + kenter(",%u,%llu", field, field_data_len); + + if (tlv_data->algo == HASH_ALGO__LAST) { + pr_debug("Digest algo not set\n"); + ret = -EBADMSG; + goto out; + } + + if (field_data_len != hash_digest_size[tlv_data->algo]) { + pr_debug("Unexpected data length %llu, expected %d\n", + field_data_len, hash_digest_size[tlv_data->algo]); + ret = -EBADMSG; + goto out; + } + + ret = digest_cache_htable_add(tlv_data->digest_cache, (u8 *)field_data, + tlv_data->algo); +out: + kleave(" = %d", ret); + return ret; +} + +/** + * parse_digest_list_entry_path - Parse DIGEST_LIST_ENTRY_PATH field + * @tlv_data: Callback data + * @field: Field identifier + * @field_data: Field data + * @field_data_len: Length of @field_data + * + * This function handles the DIGEST_LIST_ENTRY_PATH field (file path). It + * currently does not parse the data. + * + * Return: Zero. + */ +static int parse_digest_list_entry_path(struct tlv_callback_data *tlv_data, + enum digest_list_entry_fields field, + const u8 *field_data, + u64 field_data_len) +{ + kenter(",%u,%llu", field, field_data_len); + + kleave(" = 0"); + return 0; +} + +/** + * digest_list_entry_hdr_callback - DIGEST_LIST_ENTRY header callback + * @callback_data: Callback data + * @data_type: TLV data type + * @num_entries: Number of TLV data entries + * @total_len: Total length of TLV data + * + * This callback ensures that only TLV data with type DIGEST_LIST_ENTRY_DATA + * is processed. + * + * Return: 0 to skip processing the data, 1 to process the data. + */ +static int digest_list_entry_hdr_callback(void *callback_data, u64 data_type, + u64 num_entries, u64 total_len) +{ + if (data_type != DIGEST_LIST_ENTRY_DATA) + return 0; + + return 1; +} + +/** + * digest_list_entry_data_callback - DIGEST_LIST_ENTRY data callback + * @callback_data: Callback data + * @field: Field identifier + * @field_data: Field data + * @field_data_len: Length of @field_data + * + * This callback handles the fields of DIGEST_LIST_ENTRY_DATA (nested) data, + * and calls the appropriate parser. + * + * Return: Zero on success, a POSIX error code otherwise. + */ +static int digest_list_entry_data_callback(void *callback_data, u64 field, + const u8 *field_data, + u64 field_data_len) +{ + struct tlv_callback_data *tlv_data; + int ret; + + tlv_data = (struct tlv_callback_data *)callback_data; + + switch (field) { + case DIGEST_LIST_ENTRY_DIGEST: + ret = parse_digest_list_entry_digest(tlv_data, field, + field_data, + field_data_len); + break; + case DIGEST_LIST_ENTRY_PATH: + ret = parse_digest_list_entry_path(tlv_data, field, field_data, + field_data_len); + break; + default: + pr_debug("Unhandled field %s\n", + digest_list_entry_fields_str[field]); + /* Just ignore non-relevant fields. */ + ret = 0; + break; + } + + return ret; +} + +/** + * parse_digest_list_algo - Parse DIGEST_LIST_ALGO field + * @tlv_data: Callback data + * @field: Field identifier + * @field_data: Field data + * @field_data_len: Length of @field_data + * + * This function parses the DIGEST_LIST_ALGO field (digest algorithm). + * + * Return: Zero on success, a POSIX error code otherwise. + */ +static int parse_digest_list_algo(struct tlv_callback_data *tlv_data, + enum digest_list_fields field, + const u8 *field_data, u64 field_data_len) +{ + u64 algo; + int ret; + + kenter(",%u,%llu", field, field_data_len); + + if (field_data_len != sizeof(u64)) { + pr_debug("Unexpected data length %llu, expected %lu\n", + field_data_len, sizeof(u64)); + ret = -EBADMSG; + goto out; + } + + algo = __be64_to_cpu(*(u64 *)field_data); + + if (algo >= HASH_ALGO__LAST) { + pr_debug("Unexpected digest algo %llu\n", algo); + ret = -EBADMSG; + goto out; + } + + ret = digest_cache_htable_init(tlv_data->digest_cache, + tlv_data->parsed_num_entries, algo); + if (ret < 0) + goto out; + + tlv_data->algo = algo; + + pr_debug("Digest algo: %s\n", hash_algo_name[algo]); +out: + kleave(" = %d", ret); + return ret; +} + +/** + * parse_digest_list_entry - Parse DIGEST_LIST_ENTRY field + * @tlv_data: Callback data + * @field: Field identifier + * @field_data: Field data + * @field_data_len: Length of @field_data + * + * This function parses the DIGEST_LIST_ENTRY field. + * + * Return: Zero on success, a POSIX error code otherwise. + */ +static int parse_digest_list_entry(struct tlv_callback_data *tlv_data, + enum digest_list_fields field, + const u8 *field_data, u64 field_data_len) +{ + int ret; + + kenter(",%u,%llu", field, field_data_len); + + ret = tlv_parse(digest_list_entry_hdr_callback, NULL, + digest_list_entry_data_callback, tlv_data, field_data, + field_data_len, digest_list_entry_types_str, + DIGEST_LIST_ENTRY__LAST, digest_list_entry_fields_str, + DIGEST_LIST_ENTRY_FIELD__LAST); + + kleave(" = %d", ret); + return ret; +} + +/** + * digest_list_hdr_callback - DIGEST_LIST header callback + * @callback_data: Callback data + * @data_type: TLV data type + * @num_entries: Number of TLV data entries + * @total_len: Total length of TLV data + * + * This callback ensures that only TLV data with type DIGEST_LIST_FILE + * is processed (one block), and stores the total number of TLV data entries + * to later initialize a new digest cache hash table. + * + * Return: 0 to skip processing the data, 1 to process the data, a POSIX error + * code otherwise. + */ +static int digest_list_hdr_callback(void *callback_data, u64 data_type, + u64 num_entries, u64 total_len) +{ + struct tlv_callback_data *tlv_data; + + tlv_data = (struct tlv_callback_data *)callback_data; + + if (data_type != DIGEST_LIST_FILE) + return 0; + + /* At the moment we process only one block. */ + if (tlv_data->parsed_num_entries) + return -EINVAL; + + tlv_data->parsed_num_entries = num_entries; + return 1; +} + +/** + * digest_list_data_callback - DIGEST_LIST data callback + * @callback_data: Callback data + * @field: Field identifier + * @field_data: Field data + * @field_data_len: Length of @field_data + * + * This callback handles the fields of DIGEST_LIST_FILE data, and calls the + * appropriate parser. + * + * Return: Zero on success, a POSIX error code otherwise. + */ +static int digest_list_data_callback(void *callback_data, u64 field, + const u8 *field_data, u64 field_data_len) +{ + struct tlv_callback_data *tlv_data; + int ret; + + tlv_data = (struct tlv_callback_data *)callback_data; + + switch (field) { + case DIGEST_LIST_ALGO: + ret = parse_digest_list_algo(tlv_data, field, field_data, + field_data_len); + break; + case DIGEST_LIST_ENTRY: + ret = parse_digest_list_entry(tlv_data, field, field_data, + field_data_len); + break; + default: + pr_debug("Unhandled field %s\n", + digest_list_fields_str[field]); + /* Just ignore non-relevant fields. */ + ret = 0; + break; + } + + return ret; +} + +/** + * digest_list_parse_tlv - Parse a tlv digest list + * @digest_cache: Digest cache + * @data: Data to parse + * @data_len: Length of @data + * + * This function parses a tlv digest list. + * + * Return: Zero on success, a POSIX error code otherwise. + */ +int digest_list_parse_tlv(struct digest_cache *digest_cache, const u8 *data, + size_t data_len) +{ + struct tlv_callback_data tlv_data = { + .digest_cache = digest_cache, + .algo = HASH_ALGO__LAST, + .parsed_num_entries = 0, + }; + + return tlv_parse(digest_list_hdr_callback, &tlv_data, + digest_list_data_callback, &tlv_data, data, data_len, + digest_list_types_str, DIGEST_LIST__LAST, + digest_list_fields_str, DIGEST_LIST_FIELD__LAST); +} diff --git a/security/integrity/digest_cache/populate.c b/security/integrity/digest_cache/populate.c index c68c76971380..c118658f547a 100644 --- a/security/integrity/digest_cache/populate.c +++ b/security/integrity/digest_cache/populate.c @@ -13,6 +13,7 @@ #include <linux/kernel_read_file.h>
#include "internal.h" +#include "parsers/parsers.h"
/** * digest_cache_parse_digest_list - Parse a digest list @@ -61,6 +62,9 @@ static int digest_cache_parse_digest_list(struct digest_cache *digest_cache, pr_debug("Parsing %s, format: %.*s, size: %ld\n", path_str, (int)(next_sep - format), format, data_len);
+ if (!strncmp(format, "tlv-", 4)) + ret = digest_list_parse_tlv(digest_cache, data, data_len); + return ret; }