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947d705972
Add support for IMA signature verification for EC keys. Since SHA type of hashes can be used by RSA and ECDSA signature schemes we need to look at the key and derive from the key which signature scheme to use. Since this can be applied to all types of keys, we change the selection of the encoding type to be driven by the key's signature scheme rather than by the hash type. Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com> Cc: linux-integrity@vger.kernel.org Cc: David Howells <dhowells@redhat.com> Cc: keyrings@vger.kernel.org Signed-off-by: Stefan Berger <stefanb@linux.ibm.com> Reviewed-by: Vitaly Chikunov <vt@altlinux.org> Reviewed-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com> Acked-by: Mimi Zohar <zohar@linux.ibm.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
154 lines
3.7 KiB
C
154 lines
3.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2013 Intel Corporation
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*
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* Author:
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* Dmitry Kasatkin <dmitry.kasatkin@intel.com>
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*/
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#include <linux/err.h>
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#include <linux/ratelimit.h>
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#include <linux/key-type.h>
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#include <crypto/public_key.h>
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#include <crypto/hash_info.h>
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#include <keys/asymmetric-type.h>
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#include <keys/system_keyring.h>
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#include "integrity.h"
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/*
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* Request an asymmetric key.
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*/
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static struct key *request_asymmetric_key(struct key *keyring, uint32_t keyid)
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{
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struct key *key;
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char name[12];
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sprintf(name, "id:%08x", keyid);
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pr_debug("key search: \"%s\"\n", name);
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key = get_ima_blacklist_keyring();
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if (key) {
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key_ref_t kref;
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kref = keyring_search(make_key_ref(key, 1),
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&key_type_asymmetric, name, true);
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if (!IS_ERR(kref)) {
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pr_err("Key '%s' is in ima_blacklist_keyring\n", name);
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return ERR_PTR(-EKEYREJECTED);
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}
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}
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if (keyring) {
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/* search in specific keyring */
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key_ref_t kref;
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kref = keyring_search(make_key_ref(keyring, 1),
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&key_type_asymmetric, name, true);
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if (IS_ERR(kref))
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key = ERR_CAST(kref);
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else
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key = key_ref_to_ptr(kref);
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} else {
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key = request_key(&key_type_asymmetric, name, NULL);
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}
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if (IS_ERR(key)) {
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if (keyring)
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pr_err_ratelimited("Request for unknown key '%s' in '%s' keyring. err %ld\n",
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name, keyring->description,
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PTR_ERR(key));
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else
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pr_err_ratelimited("Request for unknown key '%s' err %ld\n",
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name, PTR_ERR(key));
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switch (PTR_ERR(key)) {
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/* Hide some search errors */
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case -EACCES:
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case -ENOTDIR:
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case -EAGAIN:
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return ERR_PTR(-ENOKEY);
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default:
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return key;
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}
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}
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pr_debug("%s() = 0 [%x]\n", __func__, key_serial(key));
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return key;
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}
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int asymmetric_verify(struct key *keyring, const char *sig,
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int siglen, const char *data, int datalen)
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{
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struct public_key_signature pks;
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struct signature_v2_hdr *hdr = (struct signature_v2_hdr *)sig;
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const struct public_key *pk;
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struct key *key;
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int ret;
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if (siglen <= sizeof(*hdr))
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return -EBADMSG;
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siglen -= sizeof(*hdr);
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if (siglen != be16_to_cpu(hdr->sig_size))
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return -EBADMSG;
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if (hdr->hash_algo >= HASH_ALGO__LAST)
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return -ENOPKG;
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key = request_asymmetric_key(keyring, be32_to_cpu(hdr->keyid));
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if (IS_ERR(key))
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return PTR_ERR(key);
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memset(&pks, 0, sizeof(pks));
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pks.hash_algo = hash_algo_name[hdr->hash_algo];
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pk = asymmetric_key_public_key(key);
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pks.pkey_algo = pk->pkey_algo;
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if (!strcmp(pk->pkey_algo, "rsa"))
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pks.encoding = "pkcs1";
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else if (!strncmp(pk->pkey_algo, "ecdsa-", 6))
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/* edcsa-nist-p192 etc. */
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pks.encoding = "x962";
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else if (!strcmp(pk->pkey_algo, "ecrdsa") ||
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!strcmp(pk->pkey_algo, "sm2"))
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pks.encoding = "raw";
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else
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return -ENOPKG;
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pks.digest = (u8 *)data;
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pks.digest_size = datalen;
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pks.s = hdr->sig;
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pks.s_size = siglen;
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ret = verify_signature(key, &pks);
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key_put(key);
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pr_debug("%s() = %d\n", __func__, ret);
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return ret;
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}
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/**
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* integrity_kernel_module_request - prevent crypto-pkcs1pad(rsa,*) requests
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* @kmod_name: kernel module name
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*
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* We have situation, when public_key_verify_signature() in case of RSA
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* algorithm use alg_name to store internal information in order to
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* construct an algorithm on the fly, but crypto_larval_lookup() will try
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* to use alg_name in order to load kernel module with same name.
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* Since we don't have any real "crypto-pkcs1pad(rsa,*)" kernel modules,
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* we are safe to fail such module request from crypto_larval_lookup().
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*
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* In this way we prevent modprobe execution during digsig verification
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* and avoid possible deadlock if modprobe and/or it's dependencies
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* also signed with digsig.
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*/
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int integrity_kernel_module_request(char *kmod_name)
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{
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if (strncmp(kmod_name, "crypto-pkcs1pad(rsa,", 20) == 0)
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return -EINVAL;
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return 0;
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}
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