269 lines
8 KiB
C
269 lines
8 KiB
C
/* Instantiate a public key crypto key from an X.509 Certificate
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*
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* Copyright (C) 2012, 2016 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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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#define pr_fmt(fmt) "ASYM: "fmt
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/err.h>
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#include <crypto/public_key.h>
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#include "asymmetric_keys.h"
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static bool use_builtin_keys;
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static struct asymmetric_key_id *ca_keyid;
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#ifndef MODULE
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static struct {
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struct asymmetric_key_id id;
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unsigned char data[10];
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} cakey;
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static int __init ca_keys_setup(char *str)
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{
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if (!str) /* default system keyring */
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return 1;
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if (strncmp(str, "id:", 3) == 0) {
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struct asymmetric_key_id *p = &cakey.id;
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size_t hexlen = (strlen(str) - 3) / 2;
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int ret;
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if (hexlen == 0 || hexlen > sizeof(cakey.data)) {
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pr_err("Missing or invalid ca_keys id\n");
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return 1;
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}
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ret = __asymmetric_key_hex_to_key_id(str + 3, p, hexlen);
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if (ret < 0)
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pr_err("Unparsable ca_keys id hex string\n");
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else
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ca_keyid = p; /* owner key 'id:xxxxxx' */
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} else if (strcmp(str, "builtin") == 0) {
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use_builtin_keys = true;
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}
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return 1;
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}
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__setup("ca_keys=", ca_keys_setup);
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#endif
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/**
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* restrict_link_by_signature - Restrict additions to a ring of public keys
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* @dest_keyring: Keyring being linked to.
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* @type: The type of key being added.
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* @payload: The payload of the new key.
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* @trust_keyring: A ring of keys that can be used to vouch for the new cert.
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*
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* Check the new certificate against the ones in the trust keyring. If one of
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* those is the signing key and validates the new certificate, then mark the
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* new certificate as being trusted.
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*
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* Returns 0 if the new certificate was accepted, -ENOKEY if we couldn't find a
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* matching parent certificate in the trusted list, -EKEYREJECTED if the
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* signature check fails or the key is blacklisted, -ENOPKG if the signature
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* uses unsupported crypto, or some other error if there is a matching
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* certificate but the signature check cannot be performed.
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*/
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int restrict_link_by_signature(struct key *dest_keyring,
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const struct key_type *type,
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const union key_payload *payload,
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struct key *trust_keyring)
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{
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const struct public_key_signature *sig;
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struct key *key;
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int ret;
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pr_devel("==>%s()\n", __func__);
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if (!trust_keyring)
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return -ENOKEY;
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if (type != &key_type_asymmetric)
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return -EOPNOTSUPP;
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sig = payload->data[asym_auth];
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if (!sig)
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return -ENOPKG;
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if (!sig->auth_ids[0] && !sig->auth_ids[1])
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return -ENOKEY;
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if (ca_keyid && !asymmetric_key_id_partial(sig->auth_ids[1], ca_keyid))
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return -EPERM;
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/* See if we have a key that signed this one. */
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key = find_asymmetric_key(trust_keyring,
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sig->auth_ids[0], sig->auth_ids[1],
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false);
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if (IS_ERR(key))
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return -ENOKEY;
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if (use_builtin_keys && !test_bit(KEY_FLAG_BUILTIN, &key->flags))
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ret = -ENOKEY;
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else
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ret = verify_signature(key, sig);
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key_put(key);
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return ret;
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}
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static bool match_either_id(const struct asymmetric_key_ids *pair,
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const struct asymmetric_key_id *single)
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{
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return (asymmetric_key_id_same(pair->id[0], single) ||
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asymmetric_key_id_same(pair->id[1], single));
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}
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static int key_or_keyring_common(struct key *dest_keyring,
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const struct key_type *type,
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const union key_payload *payload,
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struct key *trusted, bool check_dest)
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{
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const struct public_key_signature *sig;
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struct key *key = NULL;
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int ret;
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pr_devel("==>%s()\n", __func__);
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if (!dest_keyring)
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return -ENOKEY;
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else if (dest_keyring->type != &key_type_keyring)
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return -EOPNOTSUPP;
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if (!trusted && !check_dest)
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return -ENOKEY;
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if (type != &key_type_asymmetric)
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return -EOPNOTSUPP;
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sig = payload->data[asym_auth];
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if (!sig)
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return -ENOPKG;
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if (!sig->auth_ids[0] && !sig->auth_ids[1])
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return -ENOKEY;
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if (trusted) {
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if (trusted->type == &key_type_keyring) {
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/* See if we have a key that signed this one. */
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key = find_asymmetric_key(trusted, sig->auth_ids[0],
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sig->auth_ids[1], false);
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if (IS_ERR(key))
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key = NULL;
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} else if (trusted->type == &key_type_asymmetric) {
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const struct asymmetric_key_ids *signer_ids;
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signer_ids = asymmetric_key_ids(trusted);
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/*
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* The auth_ids come from the candidate key (the
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* one that is being considered for addition to
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* dest_keyring) and identify the key that was
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* used to sign.
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*
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* The signer_ids are identifiers for the
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* signing key specified for dest_keyring.
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*
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* The first auth_id is the preferred id, and
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* the second is the fallback. If only one
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* auth_id is present, it may match against
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* either signer_id. If two auth_ids are
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* present, the first auth_id must match one
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* signer_id and the second auth_id must match
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* the second signer_id.
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*/
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if (!sig->auth_ids[0] || !sig->auth_ids[1]) {
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const struct asymmetric_key_id *auth_id;
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auth_id = sig->auth_ids[0] ?: sig->auth_ids[1];
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if (match_either_id(signer_ids, auth_id))
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key = __key_get(trusted);
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} else if (asymmetric_key_id_same(signer_ids->id[1],
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sig->auth_ids[1]) &&
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match_either_id(signer_ids,
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sig->auth_ids[0])) {
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key = __key_get(trusted);
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}
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} else {
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return -EOPNOTSUPP;
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}
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}
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if (check_dest && !key) {
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/* See if the destination has a key that signed this one. */
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key = find_asymmetric_key(dest_keyring, sig->auth_ids[0],
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sig->auth_ids[1], false);
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if (IS_ERR(key))
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key = NULL;
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}
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if (!key)
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return -ENOKEY;
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ret = key_validate(key);
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if (ret == 0)
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ret = verify_signature(key, sig);
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key_put(key);
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return ret;
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}
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/**
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* restrict_link_by_key_or_keyring - Restrict additions to a ring of public
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* keys using the restrict_key information stored in the ring.
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* @dest_keyring: Keyring being linked to.
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* @type: The type of key being added.
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* @payload: The payload of the new key.
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* @trusted: A key or ring of keys that can be used to vouch for the new cert.
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*
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* Check the new certificate only against the key or keys passed in the data
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* parameter. If one of those is the signing key and validates the new
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* certificate, then mark the new certificate as being ok to link.
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*
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* Returns 0 if the new certificate was accepted, -ENOKEY if we
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* couldn't find a matching parent certificate in the trusted list,
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* -EKEYREJECTED if the signature check fails, -ENOPKG if the signature uses
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* unsupported crypto, or some other error if there is a matching certificate
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* but the signature check cannot be performed.
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*/
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int restrict_link_by_key_or_keyring(struct key *dest_keyring,
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const struct key_type *type,
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const union key_payload *payload,
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struct key *trusted)
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{
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return key_or_keyring_common(dest_keyring, type, payload, trusted,
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false);
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}
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/**
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* restrict_link_by_key_or_keyring_chain - Restrict additions to a ring of
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* public keys using the restrict_key information stored in the ring.
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* @dest_keyring: Keyring being linked to.
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* @type: The type of key being added.
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* @payload: The payload of the new key.
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* @trusted: A key or ring of keys that can be used to vouch for the new cert.
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*
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* Check the new certificate only against the key or keys passed in the data
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* parameter. If one of those is the signing key and validates the new
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* certificate, then mark the new certificate as being ok to link.
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*
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* Returns 0 if the new certificate was accepted, -ENOKEY if we
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* couldn't find a matching parent certificate in the trusted list,
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* -EKEYREJECTED if the signature check fails, -ENOPKG if the signature uses
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* unsupported crypto, or some other error if there is a matching certificate
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* but the signature check cannot be performed.
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*/
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int restrict_link_by_key_or_keyring_chain(struct key *dest_keyring,
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const struct key_type *type,
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const union key_payload *payload,
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struct key *trusted)
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{
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return key_or_keyring_common(dest_keyring, type, payload, trusted,
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true);
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}
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