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https://github.com/Cisco-Talos/clamav.git
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13c4788f36
ClamAV will not function when using a FIPS-enabled OpenSSL 3.x. This is because ClamAV uses MD5 and SHA1 algorithms for a variety of purposes including matching for malware detection, matching to prevent false positives on known-clean files, and for verification of MD5-based RSA digital signatures for determining CVD (signature database archive) authenticity. Interestingly, FIPS had been intentionally bypassed when creating hashes based whole buffers and whole files (by descriptor or `FILE`-pointer):78d4a9985aNote: this bypassed FIPS the 1.x way with: `EVP_MD_CTX_set_flags(ctx, EVP_MD_CTX_FLAG_NON_FIPS_ALLOW);` It was NOT disabled when using `cl_hash_init()` / `cl_update_hash()` / `cl_finish_hash()`. That likely worked by coincidence in that the hash was already calculated most of the time. It certainly would have made use of those functions if the hash had not been calculated prior:78d4a9985a/libclamav/matcher.c (L743)Regardless, bypassing FIPS entirely is not the correct solution. The FIPS restrictions against using MD5 and SHA1 are valid, particularly when verifying CVD digital siganatures, but also I think when using a hash to determine if the file is known-clean (i.e. the "clean cache" and also MD5-based and SHA1-based FP signatures). This commit extends the work to bypass FIPS using the newer 3.x method: `md = EVP_MD_fetch(NULL, alg, "-fips");` It does this for the legacy `cl_hash*()` functions including `cl_hash_init()` / `cl_update_hash()` / `cl_finish_hash()`. It also introduces extended versions that allow the caller to choose if they want to bypass FIPS: - `cl_hash_data_ex()` - `cl_hash_init_ex()` - `cl_update_hash_ex()` - `cl_finish_hash_ex()` - `cl_hash_destroy_ex()` - `cl_hash_file_fd_ex()` See the `flags` parameter for each. Ironically, this commit does NOT use the new functions at this time. The rational is that ClamAV may need MD5, SHA1, and SHA-256 hashes of the same files both for determining if the file is malware, and for determining if the file is clean. So instead, this commit will do a checks when: 1. Creating a new ClamAV scanning engine. If FIPS-mode enabled, it will automatically toggle the "FIPS limits" engine option. When loading signatures, if the engine "FIPS limits" option is enabled, then MD5 and SHA1 FP signatures will be skipped. 2. Before verifying a CVD (e.g. also for loading, unpacking when verification enabled). If "FIPS limits" or FIPS-mode are enabled, then the legacy MD5-based RSA method is disabled. Note: This commit also refactors the interface for `cl_cvdverify_ex()` and `cl_cvdunpack_ex()` so they take a `flags` parameters, rather than a single `bool`. As these functions are new in this version, it does not break the ABI. The cache was already switched to use SHA2-256, so that's not a concern for checking FIPS-mode / FIPS limits options. This adds an option for `freshclam.conf` and `clamd.conf`: FIPSCryptoHashLimits yes And an equivalent command-line option for `clamscan` and `sigtool`: --fips-limits You may programmatically enable FIPS-limits for a ClamAV engine like this: ```C cl_engine_set_num(engine, CL_ENGINE_FIPS_LIMITS, 1); ``` CLAM-2792
82 lines
2.5 KiB
C
82 lines
2.5 KiB
C
/*
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* Compilation: gcc -Wall ex1.c -o ex1 -lclamav
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*
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* Copyright (C) 2013-2025 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
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* Copyright (C) 2007-2013 Sourcefire, Inc.
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* Author: Tomasz Kojm <tkojm@clamav.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#ifndef _WIN32
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#include <unistd.h>
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#endif
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <clamav.h>
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#ifndef O_BINARY
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#define O_BINARY 0
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#endif
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/*
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* Exit codes: 0 is success. See `cl_error_t` enum from clamav.h.
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*/
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int main(int argc, char **argv)
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{
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cl_error_t ret;
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const char *filename;
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const char *destination_directory;
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uint32_t dboptions = 0;
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switch (argc) {
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case 2:
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filename = argv[1];
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destination_directory = ".";
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break;
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case 3:
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filename = argv[1];
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destination_directory = argv[2];
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break;
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case 4:
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if (strcmp(argv[1], "--no-verify") == 0) {
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filename = argv[2];
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destination_directory = argv[3];
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dboptions = CL_DB_UNSIGNED;
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} else {
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printf("Usage: %s [--no-verify] file [destination_directory]\n", argv[0]);
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return CL_EARG;
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}
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break;
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default:
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printf("Usage: %s [--no-verify] file [destination_directory]\n", argv[0]);
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return CL_EARG;
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}
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// Note: using NULL for certs_directory will disable external digital signature verification.
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ret = cl_cvdunpack_ex(filename, destination_directory, NULL, dboptions);
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if (ret != CL_SUCCESS) {
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printf("ERROR: %s\n", cl_strerror(ret));
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}
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return (int)ret;
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}
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