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![AKASHI Takahiro](/assets/img/avatar_default.png)
When the file, x509_public_key.c, was imported from linux code in
commit b4adf627d5
("lib: crypto: add x509 parser"),
x509_check_for_self_signed() was commented out for simplicity.
Now it need be enabled in order to make pkcs7_verify_one(), which will be
imported in a later patch, functional.
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
314 lines
7.1 KiB
C
314 lines
7.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Instantiate a public key crypto key from an X.509 Certificate
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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) "X.509: "fmt
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#ifdef __UBOOT__
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#include <common.h>
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#include <image.h>
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#include <dm/devres.h>
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#include <linux/compat.h>
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#include <linux/err.h>
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#include <linux/errno.h>
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#else
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#include <linux/module.h>
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#endif
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#include <linux/kernel.h>
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#ifdef __UBOOT__
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#include <crypto/x509_parser.h>
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#include <u-boot/rsa-checksum.h>
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#else
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#include <linux/slab.h>
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#include <keys/asymmetric-subtype.h>
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#include <keys/asymmetric-parser.h>
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#include <keys/system_keyring.h>
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#include <crypto/hash.h>
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#include "asymmetric_keys.h"
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#include "x509_parser.h"
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#endif
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/*
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* Set up the signature parameters in an X.509 certificate. This involves
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* digesting the signed data and extracting the signature.
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*/
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int x509_get_sig_params(struct x509_certificate *cert)
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{
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struct public_key_signature *sig = cert->sig;
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#ifdef __UBOOT__
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struct image_region region;
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#else
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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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#endif
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int ret;
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pr_devel("==>%s()\n", __func__);
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if (!cert->pub->pkey_algo)
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cert->unsupported_key = true;
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if (!sig->pkey_algo)
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cert->unsupported_sig = true;
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/* We check the hash if we can - even if we can't then verify it */
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if (!sig->hash_algo) {
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cert->unsupported_sig = true;
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return 0;
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}
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sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL);
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if (!sig->s)
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return -ENOMEM;
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sig->s_size = cert->raw_sig_size;
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#ifdef __UBOOT__
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if (!sig->hash_algo)
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return -ENOPKG;
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if (!strcmp(sig->hash_algo, "sha256"))
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sig->digest_size = SHA256_SUM_LEN;
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else if (!strcmp(sig->hash_algo, "sha1"))
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sig->digest_size = SHA1_SUM_LEN;
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else
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return -ENOPKG;
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sig->digest = calloc(1, sig->digest_size);
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if (!sig->digest)
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return -ENOMEM;
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region.data = cert->tbs;
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region.size = cert->tbs_size;
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hash_calculate(sig->hash_algo, ®ion, 1, sig->digest);
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/* TODO: is_hash_blacklisted()? */
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ret = 0;
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#else
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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(sig->hash_algo, 0, 0);
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if (IS_ERR(tfm)) {
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if (PTR_ERR(tfm) == -ENOENT) {
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cert->unsupported_sig = true;
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return 0;
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}
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return PTR_ERR(tfm);
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}
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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;
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desc = kzalloc(desc_size, GFP_KERNEL);
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if (!desc)
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goto error;
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desc->tfm = tfm;
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ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size, sig->digest);
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if (ret < 0)
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goto error_2;
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ret = is_hash_blacklisted(sig->digest, sig->digest_size, "tbs");
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if (ret == -EKEYREJECTED) {
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pr_err("Cert %*phN is blacklisted\n",
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sig->digest_size, sig->digest);
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cert->blacklisted = true;
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ret = 0;
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}
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error_2:
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kfree(desc);
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error:
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crypto_free_shash(tfm);
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#endif /* __UBOOT__ */
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pr_devel("<==%s() = %d\n", __func__, ret);
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return ret;
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}
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/*
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* Check for self-signedness in an X.509 cert and if found, check the signature
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* immediately if we can.
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*/
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int x509_check_for_self_signed(struct x509_certificate *cert)
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{
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int ret = 0;
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pr_devel("==>%s()\n", __func__);
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if (cert->raw_subject_size != cert->raw_issuer_size ||
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memcmp(cert->raw_subject, cert->raw_issuer,
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cert->raw_issuer_size) != 0)
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goto not_self_signed;
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if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) {
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/* If the AKID is present it may have one or two parts. If
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* both are supplied, both must match.
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*/
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bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]);
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bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]);
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if (!a && !b)
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goto not_self_signed;
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ret = -EKEYREJECTED;
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if (((a && !b) || (b && !a)) &&
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cert->sig->auth_ids[0] && cert->sig->auth_ids[1])
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goto out;
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}
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ret = -EKEYREJECTED;
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if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0)
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goto out;
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ret = public_key_verify_signature(cert->pub, cert->sig);
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if (ret < 0) {
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if (ret == -ENOPKG) {
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cert->unsupported_sig = true;
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ret = 0;
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}
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goto out;
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}
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pr_devel("Cert Self-signature verified");
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cert->self_signed = true;
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out:
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pr_devel("<==%s() = %d\n", __func__, ret);
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return ret;
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not_self_signed:
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pr_devel("<==%s() = 0 [not]\n", __func__);
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return 0;
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}
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#ifndef __UBOOT__
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/*
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* Attempt to parse a data blob for a key as an X509 certificate.
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*/
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static int x509_key_preparse(struct key_preparsed_payload *prep)
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{
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struct asymmetric_key_ids *kids;
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struct x509_certificate *cert;
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const char *q;
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size_t srlen, sulen;
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char *desc = NULL, *p;
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int ret;
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cert = x509_cert_parse(prep->data, prep->datalen);
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if (IS_ERR(cert))
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return PTR_ERR(cert);
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pr_devel("Cert Issuer: %s\n", cert->issuer);
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pr_devel("Cert Subject: %s\n", cert->subject);
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if (cert->unsupported_key) {
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ret = -ENOPKG;
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goto error_free_cert;
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}
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pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo);
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pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to);
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cert->pub->id_type = "X509";
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if (cert->unsupported_sig) {
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public_key_signature_free(cert->sig);
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cert->sig = NULL;
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} else {
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pr_devel("Cert Signature: %s + %s\n",
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cert->sig->pkey_algo, cert->sig->hash_algo);
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}
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/* Don't permit addition of blacklisted keys */
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ret = -EKEYREJECTED;
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if (cert->blacklisted)
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goto error_free_cert;
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/* Propose a description */
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sulen = strlen(cert->subject);
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if (cert->raw_skid) {
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srlen = cert->raw_skid_size;
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q = cert->raw_skid;
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} else {
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srlen = cert->raw_serial_size;
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q = cert->raw_serial;
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}
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ret = -ENOMEM;
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desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL);
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if (!desc)
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goto error_free_cert;
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p = memcpy(desc, cert->subject, sulen);
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p += sulen;
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*p++ = ':';
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*p++ = ' ';
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p = bin2hex(p, q, srlen);
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*p = 0;
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kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL);
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if (!kids)
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goto error_free_desc;
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kids->id[0] = cert->id;
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kids->id[1] = cert->skid;
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/* We're pinning the module by being linked against it */
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__module_get(public_key_subtype.owner);
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prep->payload.data[asym_subtype] = &public_key_subtype;
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prep->payload.data[asym_key_ids] = kids;
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prep->payload.data[asym_crypto] = cert->pub;
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prep->payload.data[asym_auth] = cert->sig;
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prep->description = desc;
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prep->quotalen = 100;
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/* We've finished with the certificate */
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cert->pub = NULL;
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cert->id = NULL;
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cert->skid = NULL;
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cert->sig = NULL;
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desc = NULL;
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ret = 0;
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error_free_desc:
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kfree(desc);
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error_free_cert:
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x509_free_certificate(cert);
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return ret;
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}
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static struct asymmetric_key_parser x509_key_parser = {
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.owner = THIS_MODULE,
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.name = "x509",
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.parse = x509_key_preparse,
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};
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/*
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* Module stuff
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*/
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static int __init x509_key_init(void)
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{
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return register_asymmetric_key_parser(&x509_key_parser);
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}
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static void __exit x509_key_exit(void)
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{
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unregister_asymmetric_key_parser(&x509_key_parser);
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}
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module_init(x509_key_init);
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module_exit(x509_key_exit);
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#endif /* !__UBOOT__ */
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MODULE_DESCRIPTION("X.509 certificate parser");
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MODULE_AUTHOR("Red Hat, Inc.");
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MODULE_LICENSE("GPL");
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