123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400 |
- /* 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 struct asymmetric_key_id *ca_keyid;
- #ifndef MODULE
- static struct {
- struct asymmetric_key_id id;
- unsigned char data[10];
- } cakey;
- static int __init ca_keys_setup(char *str)
- {
- if (!str) /* default system keyring */
- return 1;
- if (strncmp(str, "id:", 3) == 0) {
- struct asymmetric_key_id *p = &cakey.id;
- size_t hexlen = (strlen(str) - 3) / 2;
- int ret;
- if (hexlen == 0 || hexlen > sizeof(cakey.data)) {
- pr_err("Missing or invalid ca_keys id\n");
- return 1;
- }
- ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen);
- if (ret < 0)
- pr_err("Unparsable ca_keys id hex string\n");
- else
- ca_keyid = p; /* owner key 'id:xxxxxx' */
- } else if (strcmp(str, "builtin") == 0) {
- use_builtin_keys = true;
- }
- return 1;
- }
- __setup("ca_keys=", ca_keys_setup);
- #endif
- /**
- * x509_request_asymmetric_key - Request a key by X.509 certificate params.
- * @keyring: The keys to search.
- * @id: The issuer & serialNumber to look for or NULL.
- * @skid: The subjectKeyIdentifier to look for or NULL.
- * @partial: Use partial match if true, exact if false.
- *
- * Find a key in the given keyring by identifier. The preferred identifier is
- * the issuer + serialNumber and the fallback identifier is the
- * subjectKeyIdentifier. If both are given, the lookup is by the former, but
- * the latter must also match.
- */
- struct key *x509_request_asymmetric_key(struct key *keyring,
- const struct asymmetric_key_id *id,
- const struct asymmetric_key_id *skid,
- bool partial)
- {
- struct key *key;
- key_ref_t ref;
- const char *lookup;
- char *req, *p;
- int len;
- if (id) {
- lookup = id->data;
- len = id->len;
- } else {
- lookup = skid->data;
- len = skid->len;
- }
-
- /* Construct an identifier "id:<keyid>". */
- p = req = kmalloc(2 + 1 + len * 2 + 1, GFP_KERNEL);
- if (!req)
- return ERR_PTR(-ENOMEM);
- if (partial) {
- *p++ = 'i';
- *p++ = 'd';
- } else {
- *p++ = 'e';
- *p++ = 'x';
- }
- *p++ = ':';
- p = bin2hex(p, lookup, len);
- *p = 0;
- pr_debug("Look up: \"%s\"\n", req);
- ref = keyring_search(make_key_ref(keyring, 1),
- &key_type_asymmetric, req);
- if (IS_ERR(ref))
- pr_debug("Request for key '%s' err %ld\n", req, PTR_ERR(ref));
- kfree(req);
- if (IS_ERR(ref)) {
- switch (PTR_ERR(ref)) {
- /* Hide some search errors */
- case -EACCES:
- case -ENOTDIR:
- case -EAGAIN:
- return ERR_PTR(-ENOKEY);
- default:
- return ERR_CAST(ref);
- }
- }
- key = key_ref_to_ptr(ref);
- if (id && skid) {
- const struct asymmetric_key_ids *kids = asymmetric_key_ids(key);
- if (!kids->id[1]) {
- pr_debug("issuer+serial match, but expected SKID missing\n");
- goto reject;
- }
- if (!asymmetric_key_id_same(skid, kids->id[1])) {
- pr_debug("issuer+serial match, but SKID does not\n");
- goto reject;
- }
- }
-
- pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key));
- return key;
- reject:
- key_put(key);
- return ERR_PTR(-EKEYREJECTED);
- }
- EXPORT_SYMBOL_GPL(x509_request_asymmetric_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->unsupported_crypto)
- return -ENOPKG;
- 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)) {
- if (PTR_ERR(tfm) == -ENOENT) {
- cert->unsupported_crypto = true;
- return -ENOPKG;
- }
- return 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(ALIGN(digest_size, __alignof__(*desc)) + desc_size,
- GFP_KERNEL);
- if (!digest)
- goto error;
- cert->sig.digest = digest;
- cert->sig.digest_size = digest_size;
- desc = PTR_ALIGN(digest + digest_size, __alignof__(*desc));
- 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);
- if (ret == -ENOPKG)
- cert->unsupported_crypto = true;
- 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_key_id_partial(cert->akid_skid, ca_keyid))
- return -EPERM;
- key = x509_request_asymmetric_key(trust_keyring,
- cert->akid_id, cert->akid_skid,
- false);
- if (!IS_ERR(key)) {
- if (!use_builtin_keys
- || test_bit(KEY_FLAG_BUILTIN, &key->flags))
- ret = x509_check_signature(key->payload.data[asym_crypto],
- 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 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->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 period: %lld-%lld\n", cert->valid_from, cert->valid_to);
- pr_devel("Cert Signature: %s + %s\n",
- pkey_algo_name[cert->sig.pkey_algo],
- hash_algo_name[cert->sig.pkey_hash_algo]);
- 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->akid_skid && !cert->akid_id) ||
- asymmetric_key_id_same(cert->skid, cert->akid_skid) ||
- asymmetric_key_id_same(cert->id, cert->akid_id)) {
- 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);
- 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->description = desc;
- prep->quotalen = 100;
- /* We've finished with the certificate */
- cert->pub = NULL;
- cert->id = NULL;
- cert->skid = 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_LICENSE("GPL");
|