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lib: crypto: import pkcs7_verify.c from linux
The file, pkcs7_verify.c, will now be imported from linux code (crypto/asymmetric_keys/pkcs7_verify.c in 5.7) and modified to fit into U-Boot environment. In particular, pkcs7_verify_one() function will be used in a later patch to rework signature verification logic aiming to support intermediate certificates in "chain of trust." Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
This commit is contained in:
AKASHI Takahiro
Heinrich Schuchardt
parent
6244b3c7d9
commit
063499e38e
3 changed files with 528 additions and 0 deletions
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@ -49,4 +49,7 @@ config PKCS7_MESSAGE_PARSER
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This option provides support for parsing PKCS#7 format messages for
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signature data and provides the ability to verify the signature.
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config PKCS7_VERIFY
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bool
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endif # ASYMMETRIC_KEY_TYPE
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@ -44,6 +44,7 @@ obj-$(CONFIG_PKCS7_MESSAGE_PARSER) += pkcs7_message.o
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pkcs7_message-y := \
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pkcs7.asn1.o \
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pkcs7_parser.o
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obj-$(CONFIG_PKCS7_VERIFY) += pkcs7_verify.o
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$(obj)/pkcs7_parser.o: $(obj)/pkcs7.asn1.h
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$(obj)/pkcs7.asn1.o: $(obj)/pkcs7.asn1.c $(obj)/pkcs7.asn1.h
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524
lib/crypto/pkcs7_verify.c
Normal file
524
lib/crypto/pkcs7_verify.c
Normal file
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@ -0,0 +1,524 @@
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// SPDX-License-Identifier: GPL-2.0-or-later
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/* Verify the signature on a PKCS#7 message.
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*
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* Imported from crypto/asymmetric_keys/pkcs7_verify.c of linux 5.7
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* with modification marked as __UBOOT__.
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*
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* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#define pr_fmt(fmt) "PKCS7: "fmt
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#ifdef __UBOOT__
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#include <string.h>
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#include <linux/bitops.h>
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#include <linux/compat.h>
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#include <linux/asn1.h>
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#include <crypto/public_key.h>
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#include <crypto/pkcs7_parser.h>
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#else
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#include <linux/kernel.h>
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#include <linux/export.h>
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#include <linux/slab.h>
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#include <linux/err.h>
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#include <linux/asn1.h>
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#include <crypto/hash.h>
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#include <crypto/hash_info.h>
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#include <crypto/public_key.h>
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#include "pkcs7_parser.h"
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#endif
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/*
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* Digest the relevant parts of the PKCS#7 data
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*/
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#ifdef __UBOOT__
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static int pkcs7_digest(struct pkcs7_message *pkcs7,
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struct pkcs7_signed_info *sinfo)
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{
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return 0;
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}
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#else
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static int pkcs7_digest(struct pkcs7_message *pkcs7,
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struct pkcs7_signed_info *sinfo)
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{
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struct public_key_signature *sig = sinfo->sig;
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struct crypto_shash *tfm;
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struct shash_desc *desc;
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size_t desc_size;
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int ret;
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kenter(",%u,%s", sinfo->index, sinfo->sig->hash_algo);
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/* The digest was calculated already. */
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if (sig->digest)
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return 0;
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if (!sinfo->sig->hash_algo)
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return -ENOPKG;
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/* Allocate the hashing algorithm we're going to need and find out how
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* big the hash operational data will be.
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*/
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tfm = crypto_alloc_shash(sinfo->sig->hash_algo, 0, 0);
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if (IS_ERR(tfm))
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return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm);
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desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
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sig->digest_size = crypto_shash_digestsize(tfm);
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ret = -ENOMEM;
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sig->digest = kmalloc(sig->digest_size, GFP_KERNEL);
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if (!sig->digest)
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goto error_no_desc;
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desc = kzalloc(desc_size, GFP_KERNEL);
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if (!desc)
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goto error_no_desc;
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desc->tfm = tfm;
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/* Digest the message [RFC2315 9.3] */
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ret = crypto_shash_digest(desc, pkcs7->data, pkcs7->data_len,
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sig->digest);
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if (ret < 0)
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goto error;
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pr_devel("MsgDigest = [%*ph]\n", 8, sig->digest);
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/* However, if there are authenticated attributes, there must be a
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* message digest attribute amongst them which corresponds to the
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* digest we just calculated.
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*/
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if (sinfo->authattrs) {
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u8 tag;
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if (!sinfo->msgdigest) {
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pr_warn("Sig %u: No messageDigest\n", sinfo->index);
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ret = -EKEYREJECTED;
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goto error;
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}
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if (sinfo->msgdigest_len != sig->digest_size) {
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pr_debug("Sig %u: Invalid digest size (%u)\n",
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sinfo->index, sinfo->msgdigest_len);
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ret = -EBADMSG;
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goto error;
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}
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if (memcmp(sig->digest, sinfo->msgdigest,
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sinfo->msgdigest_len) != 0) {
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pr_debug("Sig %u: Message digest doesn't match\n",
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sinfo->index);
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ret = -EKEYREJECTED;
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goto error;
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}
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/* We then calculate anew, using the authenticated attributes
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* as the contents of the digest instead. Note that we need to
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* convert the attributes from a CONT.0 into a SET before we
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* hash it.
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*/
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memset(sig->digest, 0, sig->digest_size);
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ret = crypto_shash_init(desc);
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if (ret < 0)
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goto error;
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tag = ASN1_CONS_BIT | ASN1_SET;
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ret = crypto_shash_update(desc, &tag, 1);
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if (ret < 0)
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goto error;
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ret = crypto_shash_finup(desc, sinfo->authattrs,
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sinfo->authattrs_len, sig->digest);
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if (ret < 0)
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goto error;
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pr_devel("AADigest = [%*ph]\n", 8, sig->digest);
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}
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error:
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kfree(desc);
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error_no_desc:
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crypto_free_shash(tfm);
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kleave(" = %d", ret);
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return ret;
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}
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int pkcs7_get_digest(struct pkcs7_message *pkcs7, const u8 **buf, u32 *len,
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enum hash_algo *hash_algo)
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{
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struct pkcs7_signed_info *sinfo = pkcs7->signed_infos;
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int i, ret;
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/*
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* This function doesn't support messages with more than one signature.
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*/
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if (sinfo == NULL || sinfo->next != NULL)
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return -EBADMSG;
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ret = pkcs7_digest(pkcs7, sinfo);
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if (ret)
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return ret;
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*buf = sinfo->sig->digest;
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*len = sinfo->sig->digest_size;
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for (i = 0; i < HASH_ALGO__LAST; i++)
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if (!strcmp(hash_algo_name[i], sinfo->sig->hash_algo)) {
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*hash_algo = i;
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break;
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}
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return 0;
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}
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#endif /* !__UBOOT__ */
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/*
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* Find the key (X.509 certificate) to use to verify a PKCS#7 message. PKCS#7
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* uses the issuer's name and the issuing certificate serial number for
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* matching purposes. These must match the certificate issuer's name (not
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* subject's name) and the certificate serial number [RFC 2315 6.7].
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*/
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static int pkcs7_find_key(struct pkcs7_message *pkcs7,
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struct pkcs7_signed_info *sinfo)
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{
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struct x509_certificate *x509;
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unsigned certix = 1;
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kenter("%u", sinfo->index);
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for (x509 = pkcs7->certs; x509; x509 = x509->next, certix++) {
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/* I'm _assuming_ that the generator of the PKCS#7 message will
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* encode the fields from the X.509 cert in the same way in the
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* PKCS#7 message - but I can't be 100% sure of that. It's
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* possible this will need element-by-element comparison.
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*/
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if (!asymmetric_key_id_same(x509->id, sinfo->sig->auth_ids[0]))
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continue;
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pr_devel("Sig %u: Found cert serial match X.509[%u]\n",
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sinfo->index, certix);
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if (strcmp(x509->pub->pkey_algo, sinfo->sig->pkey_algo) != 0) {
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pr_warn("Sig %u: X.509 algo and PKCS#7 sig algo don't match\n",
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sinfo->index);
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continue;
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}
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sinfo->signer = x509;
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return 0;
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}
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/* The relevant X.509 cert isn't found here, but it might be found in
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* the trust keyring.
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*/
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pr_debug("Sig %u: Issuing X.509 cert not found (#%*phN)\n",
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sinfo->index,
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sinfo->sig->auth_ids[0]->len, sinfo->sig->auth_ids[0]->data);
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return 0;
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}
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/*
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* Verify the internal certificate chain as best we can.
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*/
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static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7,
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struct pkcs7_signed_info *sinfo)
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{
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struct public_key_signature *sig;
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struct x509_certificate *x509 = sinfo->signer, *p;
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struct asymmetric_key_id *auth;
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int ret;
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kenter("");
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for (p = pkcs7->certs; p; p = p->next)
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p->seen = false;
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for (;;) {
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pr_debug("verify %s: %*phN\n",
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x509->subject,
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x509->raw_serial_size, x509->raw_serial);
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x509->seen = true;
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if (x509->blacklisted) {
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/* If this cert is blacklisted, then mark everything
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* that depends on this as blacklisted too.
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*/
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sinfo->blacklisted = true;
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for (p = sinfo->signer; p != x509; p = p->signer)
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p->blacklisted = true;
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pr_debug("- blacklisted\n");
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return 0;
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}
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if (x509->unsupported_key)
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goto unsupported_crypto_in_x509;
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pr_debug("- issuer %s\n", x509->issuer);
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sig = x509->sig;
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if (sig->auth_ids[0])
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pr_debug("- authkeyid.id %*phN\n",
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sig->auth_ids[0]->len, sig->auth_ids[0]->data);
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if (sig->auth_ids[1])
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pr_debug("- authkeyid.skid %*phN\n",
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sig->auth_ids[1]->len, sig->auth_ids[1]->data);
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if (x509->self_signed) {
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/* If there's no authority certificate specified, then
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* the certificate must be self-signed and is the root
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* of the chain. Likewise if the cert is its own
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* authority.
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*/
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if (x509->unsupported_sig)
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goto unsupported_crypto_in_x509;
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x509->signer = x509;
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pr_debug("- self-signed\n");
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return 0;
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}
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/* Look through the X.509 certificates in the PKCS#7 message's
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* list to see if the next one is there.
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*/
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auth = sig->auth_ids[0];
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if (auth) {
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pr_debug("- want %*phN\n", auth->len, auth->data);
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for (p = pkcs7->certs; p; p = p->next) {
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pr_debug("- cmp [%u] %*phN\n",
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p->index, p->id->len, p->id->data);
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if (asymmetric_key_id_same(p->id, auth))
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goto found_issuer_check_skid;
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}
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} else if (sig->auth_ids[1]) {
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auth = sig->auth_ids[1];
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pr_debug("- want %*phN\n", auth->len, auth->data);
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for (p = pkcs7->certs; p; p = p->next) {
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if (!p->skid)
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continue;
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pr_debug("- cmp [%u] %*phN\n",
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p->index, p->skid->len, p->skid->data);
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if (asymmetric_key_id_same(p->skid, auth))
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goto found_issuer;
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}
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}
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/* We didn't find the root of this chain */
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pr_debug("- top\n");
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return 0;
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found_issuer_check_skid:
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/* We matched issuer + serialNumber, but if there's an
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* authKeyId.keyId, that must match the CA subjKeyId also.
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*/
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if (sig->auth_ids[1] &&
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!asymmetric_key_id_same(p->skid, sig->auth_ids[1])) {
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pr_warn("Sig %u: X.509 chain contains auth-skid nonmatch (%u->%u)\n",
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sinfo->index, x509->index, p->index);
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return -EKEYREJECTED;
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}
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found_issuer:
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pr_debug("- subject %s\n", p->subject);
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if (p->seen) {
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pr_warn("Sig %u: X.509 chain contains loop\n",
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sinfo->index);
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return 0;
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}
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ret = public_key_verify_signature(p->pub, x509->sig);
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if (ret < 0)
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return ret;
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x509->signer = p;
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if (x509 == p) {
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pr_debug("- self-signed\n");
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return 0;
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}
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x509 = p;
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#ifndef __UBOOT__
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might_sleep();
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#endif
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}
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unsupported_crypto_in_x509:
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/* Just prune the certificate chain at this point if we lack some
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* crypto module to go further. Note, however, we don't want to set
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* sinfo->unsupported_crypto as the signed info block may still be
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* validatable against an X.509 cert lower in the chain that we have a
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* trusted copy of.
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*/
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return 0;
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}
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/*
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* Verify one signed information block from a PKCS#7 message.
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*/
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#ifndef __UBOOT__
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static
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#endif
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int pkcs7_verify_one(struct pkcs7_message *pkcs7,
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struct pkcs7_signed_info *sinfo)
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{
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int ret;
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kenter(",%u", sinfo->index);
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/* First of all, digest the data in the PKCS#7 message and the
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* signed information block
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*/
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ret = pkcs7_digest(pkcs7, sinfo);
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if (ret < 0)
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return ret;
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/* Find the key for the signature if there is one */
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ret = pkcs7_find_key(pkcs7, sinfo);
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if (ret < 0)
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return ret;
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if (!sinfo->signer)
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return 0;
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pr_devel("Using X.509[%u] for sig %u\n",
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sinfo->signer->index, sinfo->index);
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|
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/* Check that the PKCS#7 signing time is valid according to the X.509
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* certificate. We can't, however, check against the system clock
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* since that may not have been set yet and may be wrong.
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*/
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if (test_bit(sinfo_has_signing_time, &sinfo->aa_set)) {
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if (sinfo->signing_time < sinfo->signer->valid_from ||
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sinfo->signing_time > sinfo->signer->valid_to) {
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pr_warn("Message signed outside of X.509 validity window\n");
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return -EKEYREJECTED;
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}
|
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}
|
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|
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/* Verify the PKCS#7 binary against the key */
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ret = public_key_verify_signature(sinfo->signer->pub, sinfo->sig);
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if (ret < 0)
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return ret;
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|
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pr_devel("Verified signature %u\n", sinfo->index);
|
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|
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/* Verify the internal certificate chain */
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return pkcs7_verify_sig_chain(pkcs7, sinfo);
|
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}
|
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|
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#ifndef __UBOOT__
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/**
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* pkcs7_verify - Verify a PKCS#7 message
|
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* @pkcs7: The PKCS#7 message to be verified
|
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* @usage: The use to which the key is being put
|
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*
|
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* Verify a PKCS#7 message is internally consistent - that is, the data digest
|
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* matches the digest in the AuthAttrs and any signature in the message or one
|
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* of the X.509 certificates it carries that matches another X.509 cert in the
|
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* message can be verified.
|
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*
|
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* This does not look to match the contents of the PKCS#7 message against any
|
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* external public keys.
|
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*
|
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* Returns, in order of descending priority:
|
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*
|
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* (*) -EKEYREJECTED if a key was selected that had a usage restriction at
|
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* odds with the specified usage, or:
|
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*
|
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* (*) -EKEYREJECTED if a signature failed to match for which we found an
|
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* appropriate X.509 certificate, or:
|
||||
*
|
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* (*) -EBADMSG if some part of the message was invalid, or:
|
||||
*
|
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* (*) 0 if a signature chain passed verification, or:
|
||||
*
|
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* (*) -EKEYREJECTED if a blacklisted key was encountered, or:
|
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*
|
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* (*) -ENOPKG if none of the signature chains are verifiable because suitable
|
||||
* crypto modules couldn't be found.
|
||||
*/
|
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int pkcs7_verify(struct pkcs7_message *pkcs7,
|
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enum key_being_used_for usage)
|
||||
{
|
||||
struct pkcs7_signed_info *sinfo;
|
||||
int actual_ret = -ENOPKG;
|
||||
int ret;
|
||||
|
||||
kenter("");
|
||||
|
||||
switch (usage) {
|
||||
case VERIFYING_MODULE_SIGNATURE:
|
||||
if (pkcs7->data_type != OID_data) {
|
||||
pr_warn("Invalid module sig (not pkcs7-data)\n");
|
||||
return -EKEYREJECTED;
|
||||
}
|
||||
if (pkcs7->have_authattrs) {
|
||||
pr_warn("Invalid module sig (has authattrs)\n");
|
||||
return -EKEYREJECTED;
|
||||
}
|
||||
break;
|
||||
case VERIFYING_FIRMWARE_SIGNATURE:
|
||||
if (pkcs7->data_type != OID_data) {
|
||||
pr_warn("Invalid firmware sig (not pkcs7-data)\n");
|
||||
return -EKEYREJECTED;
|
||||
}
|
||||
if (!pkcs7->have_authattrs) {
|
||||
pr_warn("Invalid firmware sig (missing authattrs)\n");
|
||||
return -EKEYREJECTED;
|
||||
}
|
||||
break;
|
||||
case VERIFYING_KEXEC_PE_SIGNATURE:
|
||||
if (pkcs7->data_type != OID_msIndirectData) {
|
||||
pr_warn("Invalid kexec sig (not Authenticode)\n");
|
||||
return -EKEYREJECTED;
|
||||
}
|
||||
/* Authattr presence checked in parser */
|
||||
break;
|
||||
case VERIFYING_UNSPECIFIED_SIGNATURE:
|
||||
if (pkcs7->data_type != OID_data) {
|
||||
pr_warn("Invalid unspecified sig (not pkcs7-data)\n");
|
||||
return -EKEYREJECTED;
|
||||
}
|
||||
break;
|
||||
default:
|
||||
return -EINVAL;
|
||||
}
|
||||
|
||||
for (sinfo = pkcs7->signed_infos; sinfo; sinfo = sinfo->next) {
|
||||
ret = pkcs7_verify_one(pkcs7, sinfo);
|
||||
if (sinfo->blacklisted) {
|
||||
if (actual_ret == -ENOPKG)
|
||||
actual_ret = -EKEYREJECTED;
|
||||
continue;
|
||||
}
|
||||
if (ret < 0) {
|
||||
if (ret == -ENOPKG) {
|
||||
sinfo->unsupported_crypto = true;
|
||||
continue;
|
||||
}
|
||||
kleave(" = %d", ret);
|
||||
return ret;
|
||||
}
|
||||
actual_ret = 0;
|
||||
}
|
||||
|
||||
kleave(" = %d", actual_ret);
|
||||
return actual_ret;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(pkcs7_verify);
|
||||
|
||||
/**
|
||||
* pkcs7_supply_detached_data - Supply the data needed to verify a PKCS#7 message
|
||||
* @pkcs7: The PKCS#7 message
|
||||
* @data: The data to be verified
|
||||
* @datalen: The amount of data
|
||||
*
|
||||
* Supply the detached data needed to verify a PKCS#7 message. Note that no
|
||||
* attempt to retain/pin the data is made. That is left to the caller. The
|
||||
* data will not be modified by pkcs7_verify() and will not be freed when the
|
||||
* PKCS#7 message is freed.
|
||||
*
|
||||
* Returns -EINVAL if data is already supplied in the message, 0 otherwise.
|
||||
*/
|
||||
int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7,
|
||||
const void *data, size_t datalen)
|
||||
{
|
||||
if (pkcs7->data) {
|
||||
pr_debug("Data already supplied\n");
|
||||
return -EINVAL;
|
||||
}
|
||||
pkcs7->data = data;
|
||||
pkcs7->data_len = datalen;
|
||||
return 0;
|
||||
}
|
||||
#endif /* __UBOOT__ */
|
||||
Loading…
Reference in a new issue