// SPDX-License-Identifier: GPL-2.0-or-later
/* Instantiate a public key crypto key from an X.509 Certificate
*
* Copyright (C) 2012, 2016 Red Hat, Inc. All Rights Reserved.
* Written by David Howells ([email protected])
*/
#define pr_fmt(fmt) "ASYM: "fmt
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/err.h>
#include <crypto/public_key.h>
#include "asymmetric_keys.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
/**
* restrict_link_by_signature - Restrict additions to a ring of public keys
* @dest_keyring: Keyring being linked to.
* @type: The type of key being added.
* @payload: The payload of the new key.
* @trust_keyring: A ring of keys that can be used to vouch for the new cert.
*
* 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.
*
* Returns 0 if the new certificate was accepted, -ENOKEY if we couldn't find a
* matching parent certificate in the trusted list, -EKEYREJECTED if the
* signature check fails or the key is blacklisted, -ENOPKG if the signature
* uses unsupported crypto, or some other error if there is a matching
* certificate but the signature check cannot be performed.
*/
int restrict_link_by_signature(struct key *dest_keyring,
const struct key_type *type,
const union key_payload *payload,
struct key *trust_keyring)
{
const struct public_key_signature *sig;
struct key *key;
int ret;
pr_devel("==>%s()\n", __func__);
if (!trust_keyring)
return -ENOKEY;
if (type != &key_type_asymmetric)
return -EOPNOTSUPP;
sig = payload->data[asym_auth];
if (!sig)
return -ENOPKG;
if (!sig->auth_ids[0] && !sig->auth_ids[1] && !sig->auth_ids[2])
return -ENOKEY;
if (ca_keyid && !asymmetric_key_id_partial(sig->auth_ids[1], ca_keyid))
return -EPERM;
/* See if we have a key that signed this one. */
key = find_asymmetric_key(trust_keyring,
sig->auth_ids[0], sig->auth_ids[1],
sig->auth_ids[2], false);
if (IS_ERR(key))
return -ENOKEY;
if (use_builtin_keys && !test_bit(KEY_FLAG_BUILTIN, &key->flags))
ret = -ENOKEY;
else if (IS_BUILTIN(CONFIG_SECONDARY_TRUSTED_KEYRING_SIGNED_BY_BUILTIN) &&
!strcmp(dest_keyring->description, ".secondary_trusted_keys") &&
!test_bit(KEY_FLAG_BUILTIN, &key->flags))
ret = -ENOKEY;
else
ret = verify_signature(key, sig);
key_put(key);
return ret;
}
/**
* restrict_link_by_ca - Restrict additions to a ring of CA keys
* @dest_keyring: Keyring being linked to.
* @type: The type of key being added.
* @payload: The payload of the new key.
* @trust_keyring: Unused.
*
* Check if the new certificate is a CA. If it is a CA, then mark the new
* certificate as being ok to link.
*
* Returns 0 if the new certificate was accepted, -ENOKEY if the
* certificate is not a CA. -ENOPKG if the signature uses unsupported
* crypto, or some other error if there is a matching certificate but
* the signature check cannot be performed.
*/
int restrict_link_by_ca(struct key *dest_keyring,
const struct key_type *type,
const union key_payload *payload,
struct key *trust_keyring)
{
const struct public_key *pkey;
if (type != &key_type_asymmetric)
return -EOPNOTSUPP;
pkey = payload->data[asym_crypto];
if (!pkey)
return -ENOPKG;
if (!test_bit(KEY_EFLAG_CA, &pkey->key_eflags))
return -ENOKEY;
if (!test_bit(KEY_EFLAG_KEYCERTSIGN, &pkey->key_eflags))
return -ENOKEY;
if (!IS_ENABLED(CONFIG_INTEGRITY_CA_MACHINE_KEYRING_MAX))
return 0;
if (test_bit(KEY_EFLAG_DIGITALSIG, &pkey->key_eflags))
return -ENOKEY;
return 0;
}
/**
* restrict_link_by_digsig - Restrict additions to a ring of digsig keys
* @dest_keyring: Keyring being linked to.
* @type: The type of key being added.
* @payload: The payload of the new key.
* @trust_keyring: A ring of keys that can be used to vouch for the new cert.
*
* Check if the new certificate has digitalSignature usage set. If it is,
* then mark the new certificate as being ok to link. Afterwards verify
* the new certificate against the ones in the trust_keyring.
*
* Returns 0 if the new certificate was accepted, -ENOKEY if the
* certificate is not a digsig. -ENOPKG if the signature uses unsupported
* crypto, or some other error if there is a matching certificate but
* the signature check cannot be performed.
*/
int restrict_link_by_digsig(struct key *dest_keyring,
const struct key_type *type,
const union key_payload *payload,
struct key *trust_keyring)
{
const struct public_key *pkey;
if (type != &key_type_asymmetric)
return -EOPNOTSUPP;
pkey = payload->data[asym_crypto];
if (!pkey)
return -ENOPKG;
if (!test_bit(KEY_EFLAG_DIGITALSIG, &pkey->key_eflags))
return -ENOKEY;
if (test_bit(KEY_EFLAG_CA, &pkey->key_eflags))
return -ENOKEY;
if (test_bit(KEY_EFLAG_KEYCERTSIGN, &pkey->key_eflags))
return -ENOKEY;
return restrict_link_by_signature(dest_keyring, type, payload,
trust_keyring);
}
static bool match_either_id(const struct asymmetric_key_id **pair,
const struct asymmetric_key_id *single)
{
return (asymmetric_key_id_same(pair[0], single) ||
asymmetric_key_id_same(pair[1], single));
}
static int key_or_keyring_common(struct key *dest_keyring,
const struct key_type *type,
const union key_payload *payload,
struct key *trusted, bool check_dest)
{
const struct public_key_signature *sig;
struct key *key = NULL;
int ret;
pr_devel("==>%s()\n", __func__);
if (!dest_keyring)
return -ENOKEY;
else if (dest_keyring->type != &key_type_keyring)
return -EOPNOTSUPP;
if (!trusted && !check_dest)
return -ENOKEY;
if (type != &key_type_asymmetric)
return -EOPNOTSUPP;
sig = payload->data[asym_auth];
if (!sig)
return -ENOPKG;
if (!sig->auth_ids[0] && !sig->auth_ids[1] && !sig->auth_ids[2])
return -ENOKEY;
if (trusted) {
if (trusted->type == &key_type_keyring) {
/* See if we have a key that signed this one. */
key = find_asymmetric_key(trusted, sig->auth_ids[0],
sig->auth_ids[1],
sig->auth_ids[2], false);
if (IS_ERR(key))
key = NULL;
} else if (trusted->type == &key_type_asymmetric) {
const struct asymmetric_key_id **signer_ids;
signer_ids = (const struct asymmetric_key_id **)
asymmetric_key_ids(trusted)->id;
/*
* The auth_ids come from the candidate key (the
* one that is being considered for addition to
* dest_keyring) and identify the key that was
* used to sign.
*
* The signer_ids are identifiers for the
* signing key specified for dest_keyring.
*
* The first auth_id is the preferred id, 2nd and
* 3rd are the fallbacks. If exactly one of
* auth_ids[0] and auth_ids[1] is present, it may
* match either signer_ids[0] or signed_ids[1].
* If both are present the first one may match
* either signed_id but the second one must match
* the second signer_id. If neither of them is
* available, auth_ids[2] is matched against
* signer_ids[2] as a fallback.
*/
if (!sig->auth_ids[0] && !sig->auth_ids[1]) {
if (asymmetric_key_id_same(signer_ids[2],
sig->auth_ids[2]))
key = __key_get(trusted);
} else if (!sig->auth_ids[0] || !sig->auth_ids[1]) {
const struct asymmetric_key_id *auth_id;
auth_id = sig->auth_ids[0] ?: sig->auth_ids[1];
if (match_either_id(signer_ids, auth_id))
key = __key_get(trusted);
} else if (asymmetric_key_id_same(signer_ids[1],
sig->auth_ids[1]) &&
match_either_id(signer_ids,
sig->auth_ids[0])) {
key = __key_get(trusted);
}
} else {
return -EOPNOTSUPP;
}
}
if (check_dest && !key) {
/* See if the destination has a key that signed this one. */
key = find_asymmetric_key(dest_keyring, sig->auth_ids[0],
sig->auth_ids[1], sig->auth_ids[2],
false);
if (IS_ERR(key))
key = NULL;
}
if (!key)
return -ENOKEY;
ret = key_validate(key);
if (ret == 0)
ret = verify_signature(key, sig);
key_put(key);
return ret;
}
/**
* restrict_link_by_key_or_keyring - Restrict additions to a ring of public
* keys using the restrict_key information stored in the ring.
* @dest_keyring: Keyring being linked to.
* @type: The type of key being added.
* @payload: The payload of the new key.
* @trusted: A key or ring of keys that can be used to vouch for the new cert.
*
* Check the new certificate only against the key or keys passed in the data
* parameter. If one of those is the signing key and validates the new
* certificate, then mark the new certificate as being ok to link.
*
* Returns 0 if the new certificate was accepted, -ENOKEY if we
* couldn't find a matching parent certificate in the trusted list,
* -EKEYREJECTED if the signature check fails, -ENOPKG if the signature uses
* unsupported crypto, or some other error if there is a matching certificate
* but the signature check cannot be performed.
*/
int restrict_link_by_key_or_keyring(struct key *dest_keyring,
const struct key_type *type,
const union key_payload *payload,
struct key *trusted)
{
return key_or_keyring_common(dest_keyring, type, payload, trusted,
false);
}
/**
* restrict_link_by_key_or_keyring_chain - Restrict additions to a ring of
* public keys using the restrict_key information stored in the ring.
* @dest_keyring: Keyring being linked to.
* @type: The type of key being added.
* @payload: The payload of the new key.
* @trusted: A key or ring of keys that can be used to vouch for the new cert.
*
* Check the new certificate against the key or keys passed in the data
* parameter and against the keys already linked to the destination keyring. If
* one of those is the signing key and validates the new certificate, then mark
* the new certificate as being ok to link.
*
* Returns 0 if the new certificate was accepted, -ENOKEY if we
* couldn't find a matching parent certificate in the trusted list,
* -EKEYREJECTED if the signature check fails, -ENOPKG if the signature uses
* unsupported crypto, or some other error if there is a matching certificate
* but the signature check cannot be performed.
*/
int restrict_link_by_key_or_keyring_chain(struct key *dest_keyring,
const struct key_type *type,
const union key_payload *payload,
struct key *trusted)
{
return key_or_keyring_common(dest_keyring, type, payload, trusted,
true);
}
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