diff options
Diffstat (limited to 'crypto/asymmetric_keys/restrict.c')
| -rw-r--r-- | crypto/asymmetric_keys/restrict.c | 359 |
1 files changed, 359 insertions, 0 deletions
diff --git a/crypto/asymmetric_keys/restrict.c b/crypto/asymmetric_keys/restrict.c new file mode 100644 index 0000000000..6b69ea40da --- /dev/null +++ b/crypto/asymmetric_keys/restrict.c @@ -0,0 +1,359 @@ +// 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 (dhowells@redhat.com) + */ + +#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 + 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); +} |