| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* Instantiate a public key crypto key from an X.509 Certificate |
| * |
| * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved. |
| * Written by David Howells (dhowells@redhat.com) |
| */ |
| |
| #define pr_fmt(fmt) "X.509: "fmt |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/slab.h> |
| #include <keys/asymmetric-subtype.h> |
| #include <keys/asymmetric-parser.h> |
| #include <keys/system_keyring.h> |
| #include <crypto/hash.h> |
| #include "asymmetric_keys.h" |
| #include "x509_parser.h" |
| |
| /* |
| * Set up the signature parameters in an X.509 certificate. This involves |
| * digesting the signed data and extracting the signature. |
| */ |
| int x509_get_sig_params(struct x509_certificate *cert) |
| { |
| struct public_key_signature *sig = cert->sig; |
| struct crypto_shash *tfm; |
| struct shash_desc *desc; |
| size_t desc_size; |
| int ret; |
| |
| pr_devel("==>%s()\n", __func__); |
| |
| sig->data = cert->tbs; |
| sig->data_size = cert->tbs_size; |
| |
| sig->s = kmemdup(cert->raw_sig, cert->raw_sig_size, GFP_KERNEL); |
| if (!sig->s) |
| return -ENOMEM; |
| |
| sig->s_size = cert->raw_sig_size; |
| |
| /* Allocate the hashing algorithm we're going to need and find out how |
| * big the hash operational data will be. |
| */ |
| tfm = crypto_alloc_shash(sig->hash_algo, 0, 0); |
| if (IS_ERR(tfm)) { |
| if (PTR_ERR(tfm) == -ENOENT) { |
| cert->unsupported_sig = true; |
| return 0; |
| } |
| return PTR_ERR(tfm); |
| } |
| |
| desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); |
| sig->digest_size = crypto_shash_digestsize(tfm); |
| |
| ret = -ENOMEM; |
| sig->digest = kmalloc(sig->digest_size, GFP_KERNEL); |
| if (!sig->digest) |
| goto error; |
| |
| desc = kzalloc(desc_size, GFP_KERNEL); |
| if (!desc) |
| goto error; |
| |
| desc->tfm = tfm; |
| |
| ret = crypto_shash_digest(desc, cert->tbs, cert->tbs_size, sig->digest); |
| if (ret < 0) |
| goto error_2; |
| |
| ret = is_hash_blacklisted(sig->digest, sig->digest_size, |
| BLACKLIST_HASH_X509_TBS); |
| if (ret == -EKEYREJECTED) { |
| pr_err("Cert %*phN is blacklisted\n", |
| sig->digest_size, sig->digest); |
| cert->blacklisted = true; |
| ret = 0; |
| } |
| |
| error_2: |
| kfree(desc); |
| error: |
| crypto_free_shash(tfm); |
| pr_devel("<==%s() = %d\n", __func__, ret); |
| return ret; |
| } |
| |
| /* |
| * Check for self-signedness in an X.509 cert and if found, check the signature |
| * immediately if we can. |
| */ |
| int x509_check_for_self_signed(struct x509_certificate *cert) |
| { |
| int ret = 0; |
| |
| pr_devel("==>%s()\n", __func__); |
| |
| if (cert->raw_subject_size != cert->raw_issuer_size || |
| memcmp(cert->raw_subject, cert->raw_issuer, |
| cert->raw_issuer_size) != 0) |
| goto not_self_signed; |
| |
| if (cert->sig->auth_ids[0] || cert->sig->auth_ids[1]) { |
| /* If the AKID is present it may have one or two parts. If |
| * both are supplied, both must match. |
| */ |
| bool a = asymmetric_key_id_same(cert->skid, cert->sig->auth_ids[1]); |
| bool b = asymmetric_key_id_same(cert->id, cert->sig->auth_ids[0]); |
| |
| if (!a && !b) |
| goto not_self_signed; |
| |
| ret = -EKEYREJECTED; |
| if (((a && !b) || (b && !a)) && |
| cert->sig->auth_ids[0] && cert->sig->auth_ids[1]) |
| goto out; |
| } |
| |
| ret = public_key_verify_signature(cert->pub, cert->sig); |
| if (ret < 0) { |
| if (ret == -ENOPKG) { |
| cert->unsupported_sig = true; |
| ret = 0; |
| } |
| goto out; |
| } |
| |
| pr_devel("Cert Self-signature verified"); |
| cert->self_signed = true; |
| |
| out: |
| pr_devel("<==%s() = %d\n", __func__, ret); |
| return ret; |
| |
| not_self_signed: |
| pr_devel("<==%s() = 0 [not]\n", __func__); |
| return 0; |
| } |
| |
| /* |
| * Attempt to parse a data blob for a key as an X509 certificate. |
| */ |
| static int x509_key_preparse(struct key_preparsed_payload *prep) |
| { |
| struct asymmetric_key_ids *kids; |
| struct x509_certificate *cert; |
| const char *q; |
| size_t srlen, sulen; |
| char *desc = NULL, *p; |
| int ret; |
| |
| cert = x509_cert_parse(prep->data, prep->datalen); |
| if (IS_ERR(cert)) |
| return PTR_ERR(cert); |
| |
| pr_devel("Cert Issuer: %s\n", cert->issuer); |
| pr_devel("Cert Subject: %s\n", cert->subject); |
| pr_devel("Cert Key Algo: %s\n", cert->pub->pkey_algo); |
| pr_devel("Cert Valid period: %lld-%lld\n", cert->valid_from, cert->valid_to); |
| |
| cert->pub->id_type = "X509"; |
| |
| if (cert->unsupported_sig) { |
| public_key_signature_free(cert->sig); |
| cert->sig = NULL; |
| } else { |
| pr_devel("Cert Signature: %s + %s\n", |
| cert->sig->pkey_algo, cert->sig->hash_algo); |
| } |
| |
| /* Don't permit addition of blacklisted keys */ |
| ret = -EKEYREJECTED; |
| if (cert->blacklisted) |
| goto error_free_cert; |
| |
| /* Propose a description */ |
| sulen = strlen(cert->subject); |
| if (cert->raw_skid) { |
| srlen = cert->raw_skid_size; |
| q = cert->raw_skid; |
| } else { |
| srlen = cert->raw_serial_size; |
| q = cert->raw_serial; |
| } |
| |
| ret = -ENOMEM; |
| desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL); |
| if (!desc) |
| goto error_free_cert; |
| p = memcpy(desc, cert->subject, sulen); |
| p += sulen; |
| *p++ = ':'; |
| *p++ = ' '; |
| p = bin2hex(p, q, srlen); |
| *p = 0; |
| |
| kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL); |
| if (!kids) |
| goto error_free_desc; |
| kids->id[0] = cert->id; |
| kids->id[1] = cert->skid; |
| kids->id[2] = asymmetric_key_generate_id(cert->raw_subject, |
| cert->raw_subject_size, |
| "", 0); |
| if (IS_ERR(kids->id[2])) { |
| ret = PTR_ERR(kids->id[2]); |
| goto error_free_kids; |
| } |
| |
| /* We're pinning the module by being linked against it */ |
| __module_get(public_key_subtype.owner); |
| prep->payload.data[asym_subtype] = &public_key_subtype; |
| prep->payload.data[asym_key_ids] = kids; |
| prep->payload.data[asym_crypto] = cert->pub; |
| prep->payload.data[asym_auth] = cert->sig; |
| prep->description = desc; |
| prep->quotalen = 100; |
| |
| /* We've finished with the certificate */ |
| cert->pub = NULL; |
| cert->id = NULL; |
| cert->skid = NULL; |
| cert->sig = NULL; |
| desc = NULL; |
| kids = NULL; |
| ret = 0; |
| |
| error_free_kids: |
| kfree(kids); |
| error_free_desc: |
| kfree(desc); |
| error_free_cert: |
| x509_free_certificate(cert); |
| return ret; |
| } |
| |
| static struct asymmetric_key_parser x509_key_parser = { |
| .owner = THIS_MODULE, |
| .name = "x509", |
| .parse = x509_key_preparse, |
| }; |
| |
| /* |
| * Module stuff |
| */ |
| static int __init x509_key_init(void) |
| { |
| return register_asymmetric_key_parser(&x509_key_parser); |
| } |
| |
| static void __exit x509_key_exit(void) |
| { |
| unregister_asymmetric_key_parser(&x509_key_parser); |
| } |
| |
| module_init(x509_key_init); |
| module_exit(x509_key_exit); |
| |
| MODULE_DESCRIPTION("X.509 certificate parser"); |
| MODULE_AUTHOR("Red Hat, Inc."); |
| MODULE_LICENSE("GPL"); |