From: Dmitry Safonov Date: Tue, 10 Mar 2026 17:40:39 +0000 (+0000) Subject: ima_fs: Correctly create securityfs files for unsupported hash algos X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=d7bd8cf0b348d3edae7bee33e74a32b21668b181;p=thirdparty%2Fkernel%2Flinux.git ima_fs: Correctly create securityfs files for unsupported hash algos ima_tpm_chip->allocated_banks[i].crypto_id is initialized to HASH_ALGO__LAST if the TPM algorithm is not supported. However there are places relying on the algorithm to be valid because it is accessed by hash_algo_name[]. On 6.12.40 I observe the following read out-of-bounds in hash_algo_name: ================================================================== BUG: KASAN: global-out-of-bounds in create_securityfs_measurement_lists+0x396/0x440 Read of size 8 at addr ffffffff83e18138 by task swapper/0/1 CPU: 4 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.40 #3 Call Trace: dump_stack_lvl+0x61/0x90 print_report+0xc4/0x580 ? kasan_addr_to_slab+0x26/0x80 ? create_securityfs_measurement_lists+0x396/0x440 kasan_report+0xc2/0x100 ? create_securityfs_measurement_lists+0x396/0x440 create_securityfs_measurement_lists+0x396/0x440 ima_fs_init+0xa3/0x300 ima_init+0x7d/0xd0 init_ima+0x28/0x100 do_one_initcall+0xa6/0x3e0 kernel_init_freeable+0x455/0x740 kernel_init+0x24/0x1d0 ret_from_fork+0x38/0x80 ret_from_fork_asm+0x11/0x20 The buggy address belongs to the variable: hash_algo_name+0xb8/0x420 Memory state around the buggy address: ffffffff83e18000: 00 01 f9 f9 f9 f9 f9 f9 00 01 f9 f9 f9 f9 f9 f9 ffffffff83e18080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffffffff83e18100: 00 00 00 00 00 00 00 f9 f9 f9 f9 f9 00 05 f9 f9 ^ ffffffff83e18180: f9 f9 f9 f9 00 00 00 00 00 00 00 04 f9 f9 f9 f9 ffffffff83e18200: 00 00 00 00 00 00 00 00 04 f9 f9 f9 f9 f9 f9 f9 ================================================================== Seems like the TPM chip supports sha3_256, which isn't yet in tpm_algorithms: tpm tpm0: TPM with unsupported bank algorithm 0x0027 That's TPM_ALG_SHA3_256 == 0x0027 from "Trusted Platform Module 2.0 Library Part 2: Structures", page 51 [1]. See also the related U-Boot algorithms update [2]. Thus solve the problem by creating a file name with "_tpm_alg_" postfix if the crypto algorithm isn't initialized. This is how it looks on the test machine (patch ported to v6.12 release): # ls -1 /sys/kernel/security/ima/ ascii_runtime_measurements ascii_runtime_measurements_tpm_alg_27 ascii_runtime_measurements_sha1 ascii_runtime_measurements_sha256 binary_runtime_measurements binary_runtime_measurements_tpm_alg_27 binary_runtime_measurements_sha1 binary_runtime_measurements_sha256 policy runtime_measurements_count violations [1]: https://trustedcomputinggroup.org/wp-content/uploads/Trusted-Platform-Module-2.0-Library-Part-2-Version-184_pub.pdf [2]: https://lists.denx.de/pipermail/u-boot/2024-July/558835.html Fixes: 9fa8e7625008 ("ima: add crypto agility support for template-hash algorithm") Signed-off-by: Dmitry Safonov Cc: Enrico Bravi Cc: Silvia Sisinni Cc: Roberto Sassu Cc: Mimi Zohar Reviewed-by: Roberto Sassu Tested-by: Roberto Sassu Link: https://github.com/linux-integrity/linux/issues/14 Signed-off-by: Mimi Zohar --- diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c index 23d3a14b8ce36..ca4931a95098d 100644 --- a/security/integrity/ima/ima_fs.c +++ b/security/integrity/ima/ima_fs.c @@ -398,16 +398,24 @@ static int __init create_securityfs_measurement_lists(void) char file_name[NAME_MAX + 1]; struct dentry *dentry; - sprintf(file_name, "ascii_runtime_measurements_%s", - hash_algo_name[algo]); + if (algo == HASH_ALGO__LAST) + sprintf(file_name, "ascii_runtime_measurements_tpm_alg_%x", + ima_tpm_chip->allocated_banks[i].alg_id); + else + sprintf(file_name, "ascii_runtime_measurements_%s", + hash_algo_name[algo]); dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP, ima_dir, (void *)(uintptr_t)i, &ima_ascii_measurements_ops); if (IS_ERR(dentry)) return PTR_ERR(dentry); - sprintf(file_name, "binary_runtime_measurements_%s", - hash_algo_name[algo]); + if (algo == HASH_ALGO__LAST) + sprintf(file_name, "binary_runtime_measurements_tpm_alg_%x", + ima_tpm_chip->allocated_banks[i].alg_id); + else + sprintf(file_name, "binary_runtime_measurements_%s", + hash_algo_name[algo]); dentry = securityfs_create_file(file_name, S_IRUSR | S_IRGRP, ima_dir, (void *)(uintptr_t)i, &ima_measurements_ops);