| /* 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) |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public Licence |
| * as published by the Free Software Foundation; either version |
| * 2 of the Licence, or (at your option) any later version. |
| */ |
| |
| #define pr_fmt(fmt) "X.509: "fmt |
| #include <linux/module.h> |
| #include <linux/kernel.h> |
| #include <linux/slab.h> |
| #include <linux/err.h> |
| #include <linux/mpi.h> |
| #include <linux/asn1_decoder.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 "public_key.h" |
| #include "x509_parser.h" |
| |
| static bool use_builtin_keys; |
| static char *ca_keyid; |
| |
| #ifndef MODULE |
| static int __init ca_keys_setup(char *str) |
| { |
| if (!str) /* default system keyring */ |
| return 1; |
| |
| if (strncmp(str, "id:", 3) == 0) |
| ca_keyid = str; /* owner key 'id:xxxxxx' */ |
| else if (strcmp(str, "builtin") == 0) |
| use_builtin_keys = true; |
| |
| return 1; |
| } |
| __setup("ca_keys=", ca_keys_setup); |
| #endif |
| |
| /* |
| * Find a key in the given keyring by issuer and authority. |
| */ |
| static struct key *x509_request_asymmetric_key(struct key *keyring, |
| const char *signer, |
| size_t signer_len, |
| const char *authority, |
| size_t auth_len) |
| { |
| key_ref_t key; |
| char *id; |
| |
| /* Construct an identifier. */ |
| id = kmalloc(signer_len + 2 + auth_len + 1, GFP_KERNEL); |
| if (!id) |
| return ERR_PTR(-ENOMEM); |
| |
| memcpy(id, signer, signer_len); |
| id[signer_len + 0] = ':'; |
| id[signer_len + 1] = ' '; |
| memcpy(id + signer_len + 2, authority, auth_len); |
| id[signer_len + 2 + auth_len] = 0; |
| |
| pr_debug("Look up: \"%s\"\n", id); |
| |
| key = keyring_search(make_key_ref(keyring, 1), |
| &key_type_asymmetric, id); |
| if (IS_ERR(key)) |
| pr_debug("Request for module key '%s' err %ld\n", |
| id, PTR_ERR(key)); |
| kfree(id); |
| |
| if (IS_ERR(key)) { |
| switch (PTR_ERR(key)) { |
| /* Hide some search errors */ |
| case -EACCES: |
| case -ENOTDIR: |
| case -EAGAIN: |
| return ERR_PTR(-ENOKEY); |
| default: |
| return ERR_CAST(key); |
| } |
| } |
| |
| pr_devel("<==%s() = 0 [%x]\n", __func__, |
| key_serial(key_ref_to_ptr(key))); |
| return key_ref_to_ptr(key); |
| } |
| |
| /* |
| * 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 crypto_shash *tfm; |
| struct shash_desc *desc; |
| size_t digest_size, desc_size; |
| void *digest; |
| int ret; |
| |
| pr_devel("==>%s()\n", __func__); |
| |
| if (cert->sig.rsa.s) |
| return 0; |
| |
| cert->sig.rsa.s = mpi_read_raw_data(cert->raw_sig, cert->raw_sig_size); |
| if (!cert->sig.rsa.s) |
| return -ENOMEM; |
| cert->sig.nr_mpi = 1; |
| |
| /* Allocate the hashing algorithm we're going to need and find out how |
| * big the hash operational data will be. |
| */ |
| tfm = crypto_alloc_shash(hash_algo_name[cert->sig.pkey_hash_algo], 0, 0); |
| if (IS_ERR(tfm)) |
| return (PTR_ERR(tfm) == -ENOENT) ? -ENOPKG : PTR_ERR(tfm); |
| |
| desc_size = crypto_shash_descsize(tfm) + sizeof(*desc); |
| digest_size = crypto_shash_digestsize(tfm); |
| |
| /* We allocate the hash operational data storage on the end of the |
| * digest storage space. |
| */ |
| ret = -ENOMEM; |
| digest = kzalloc(digest_size + desc_size, GFP_KERNEL); |
| if (!digest) |
| goto error; |
| |
| cert->sig.digest = digest; |
| cert->sig.digest_size = digest_size; |
| |
| desc = digest + digest_size; |
| desc->tfm = tfm; |
| desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP; |
| |
| ret = crypto_shash_init(desc); |
| if (ret < 0) |
| goto error; |
| might_sleep(); |
| ret = crypto_shash_finup(desc, cert->tbs, cert->tbs_size, digest); |
| error: |
| crypto_free_shash(tfm); |
| pr_devel("<==%s() = %d\n", __func__, ret); |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(x509_get_sig_params); |
| |
| /* |
| * Check the signature on a certificate using the provided public key |
| */ |
| int x509_check_signature(const struct public_key *pub, |
| struct x509_certificate *cert) |
| { |
| int ret; |
| |
| pr_devel("==>%s()\n", __func__); |
| |
| ret = x509_get_sig_params(cert); |
| if (ret < 0) |
| return ret; |
| |
| ret = public_key_verify_signature(pub, &cert->sig); |
| pr_debug("Cert Verification: %d\n", ret); |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(x509_check_signature); |
| |
| /* |
| * Check the new certificate against the ones in the trust keyring. If one of |
| * those is the signing key and validates the new certificate, then mark the |
| * new certificate as being trusted. |
| * |
| * Return 0 if the new certificate was successfully validated, 1 if we couldn't |
| * find a matching parent certificate in the trusted list and an error if there |
| * is a matching certificate but the signature check fails. |
| */ |
| static int x509_validate_trust(struct x509_certificate *cert, |
| struct key *trust_keyring) |
| { |
| struct key *key; |
| int ret = 1; |
| |
| if (!trust_keyring) |
| return -EOPNOTSUPP; |
| |
| if (ca_keyid && !asymmetric_keyid_match(cert->authority, ca_keyid)) |
| return -EPERM; |
| |
| key = x509_request_asymmetric_key(trust_keyring, |
| cert->issuer, strlen(cert->issuer), |
| cert->authority, |
| strlen(cert->authority)); |
| if (!IS_ERR(key)) { |
| if (!use_builtin_keys |
| || test_bit(KEY_FLAG_BUILTIN, &key->flags)) |
| ret = x509_check_signature(key->payload.data, cert); |
| key_put(key); |
| } |
| return ret; |
| } |
| |
| /* |
| * Attempt to parse a data blob for a key as an X509 certificate. |
| */ |
| static int x509_key_preparse(struct key_preparsed_payload *prep) |
| { |
| struct x509_certificate *cert; |
| size_t srlen, sulen; |
| char *desc = NULL; |
| 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->pub->pkey_algo >= PKEY_ALGO__LAST || |
| cert->sig.pkey_algo >= PKEY_ALGO__LAST || |
| cert->sig.pkey_hash_algo >= PKEY_HASH__LAST || |
| !pkey_algo[cert->pub->pkey_algo] || |
| !pkey_algo[cert->sig.pkey_algo] || |
| !hash_algo_name[cert->sig.pkey_hash_algo]) { |
| ret = -ENOPKG; |
| goto error_free_cert; |
| } |
| |
| pr_devel("Cert Key Algo: %s\n", pkey_algo_name[cert->pub->pkey_algo]); |
| pr_devel("Cert Valid From: %04ld-%02d-%02d %02d:%02d:%02d\n", |
| cert->valid_from.tm_year + 1900, cert->valid_from.tm_mon + 1, |
| cert->valid_from.tm_mday, cert->valid_from.tm_hour, |
| cert->valid_from.tm_min, cert->valid_from.tm_sec); |
| pr_devel("Cert Valid To: %04ld-%02d-%02d %02d:%02d:%02d\n", |
| cert->valid_to.tm_year + 1900, cert->valid_to.tm_mon + 1, |
| cert->valid_to.tm_mday, cert->valid_to.tm_hour, |
| cert->valid_to.tm_min, cert->valid_to.tm_sec); |
| pr_devel("Cert Signature: %s + %s\n", |
| pkey_algo_name[cert->sig.pkey_algo], |
| hash_algo_name[cert->sig.pkey_hash_algo]); |
| |
| if (!cert->fingerprint) { |
| pr_warn("Cert for '%s' must have a SubjKeyId extension\n", |
| cert->subject); |
| ret = -EKEYREJECTED; |
| goto error_free_cert; |
| } |
| |
| cert->pub->algo = pkey_algo[cert->pub->pkey_algo]; |
| cert->pub->id_type = PKEY_ID_X509; |
| |
| /* Check the signature on the key if it appears to be self-signed */ |
| if (!cert->authority || |
| strcmp(cert->fingerprint, cert->authority) == 0) { |
| ret = x509_check_signature(cert->pub, cert); /* self-signed */ |
| if (ret < 0) |
| goto error_free_cert; |
| } else if (!prep->trusted) { |
| ret = x509_validate_trust(cert, get_system_trusted_keyring()); |
| if (!ret) |
| prep->trusted = 1; |
| } |
| |
| /* Propose a description */ |
| sulen = strlen(cert->subject); |
| srlen = strlen(cert->fingerprint); |
| ret = -ENOMEM; |
| desc = kmalloc(sulen + 2 + srlen + 1, GFP_KERNEL); |
| if (!desc) |
| goto error_free_cert; |
| memcpy(desc, cert->subject, sulen); |
| desc[sulen] = ':'; |
| desc[sulen + 1] = ' '; |
| memcpy(desc + sulen + 2, cert->fingerprint, srlen); |
| desc[sulen + 2 + srlen] = 0; |
| |
| /* We're pinning the module by being linked against it */ |
| __module_get(public_key_subtype.owner); |
| prep->type_data[0] = &public_key_subtype; |
| prep->type_data[1] = cert->fingerprint; |
| prep->payload[0] = cert->pub; |
| prep->description = desc; |
| prep->quotalen = 100; |
| |
| /* We've finished with the certificate */ |
| cert->pub = NULL; |
| cert->fingerprint = NULL; |
| desc = NULL; |
| ret = 0; |
| |
| 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_LICENSE("GPL"); |