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-rw-r--r--crypto/asymmetric_keys/restrict.c359
1 files changed, 359 insertions, 0 deletions
diff --git a/crypto/asymmetric_keys/restrict.c b/crypto/asymmetric_keys/restrict.c
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+++ b/crypto/asymmetric_keys/restrict.c
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+// 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);
+}