diff options
Diffstat (limited to 'crypto/asymmetric_keys/x509_public_key.c')
| -rw-r--r-- | crypto/asymmetric_keys/x509_public_key.c | 278 |
1 files changed, 278 insertions, 0 deletions
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c new file mode 100644 index 000000000..b8135c38f --- /dev/null +++ b/crypto/asymmetric_keys/x509_public_key.c @@ -0,0 +1,278 @@ +// 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; + + if (!cert->pub->pkey_algo) + cert->unsupported_key = true; + + if (!sig->pkey_algo) + cert->unsupported_sig = true; + + /* We check the hash if we can - even if we can't then verify it */ + if (!sig->hash_algo) { + cert->unsupported_sig = true; + return 0; + } + + 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, "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 = -EKEYREJECTED; + if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0) + goto out; + + if (cert->unsupported_sig) { + ret = 0; + 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); + + if (cert->unsupported_key) { + ret = -ENOPKG; + goto error_free_cert; + } + + 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; + + /* 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; + ret = 0; + +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"); |