diff options
Diffstat (limited to 'security/integrity/digsig_asymmetric.c')
| -rw-r--r-- | security/integrity/digsig_asymmetric.c | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/security/integrity/digsig_asymmetric.c b/security/integrity/digsig_asymmetric.c new file mode 100644 index 000000000..895f4b9ce --- /dev/null +++ b/security/integrity/digsig_asymmetric.c @@ -0,0 +1,157 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2013 Intel Corporation + * + * Author: + * Dmitry Kasatkin <dmitry.kasatkin@intel.com> + */ + +#include <linux/err.h> +#include <linux/ratelimit.h> +#include <linux/key-type.h> +#include <crypto/public_key.h> +#include <crypto/hash_info.h> +#include <keys/asymmetric-type.h> +#include <keys/system_keyring.h> + +#include "integrity.h" + +/* + * Request an asymmetric key. + */ +static struct key *request_asymmetric_key(struct key *keyring, uint32_t keyid) +{ + struct key *key; + char name[12]; + + sprintf(name, "id:%08x", keyid); + + pr_debug("key search: \"%s\"\n", name); + + key = get_ima_blacklist_keyring(); + if (key) { + key_ref_t kref; + + kref = keyring_search(make_key_ref(key, 1), + &key_type_asymmetric, name, true); + if (!IS_ERR(kref)) { + pr_err("Key '%s' is in ima_blacklist_keyring\n", name); + return ERR_PTR(-EKEYREJECTED); + } + } + + if (keyring) { + /* search in specific keyring */ + key_ref_t kref; + + kref = keyring_search(make_key_ref(keyring, 1), + &key_type_asymmetric, name, true); + if (IS_ERR(kref)) + key = ERR_CAST(kref); + else + key = key_ref_to_ptr(kref); + } else { + key = request_key(&key_type_asymmetric, name, NULL); + } + + if (IS_ERR(key)) { + if (keyring) + pr_err_ratelimited("Request for unknown key '%s' in '%s' keyring. err %ld\n", + name, keyring->description, + PTR_ERR(key)); + else + pr_err_ratelimited("Request for unknown key '%s' err %ld\n", + name, PTR_ERR(key)); + + switch (PTR_ERR(key)) { + /* Hide some search errors */ + case -EACCES: + case -ENOTDIR: + case -EAGAIN: + return ERR_PTR(-ENOKEY); + default: + return key; + } + } + + pr_debug("%s() = 0 [%x]\n", __func__, key_serial(key)); + + return key; +} + +int asymmetric_verify(struct key *keyring, const char *sig, + int siglen, const char *data, int datalen) +{ + struct public_key_signature pks; + struct signature_v2_hdr *hdr = (struct signature_v2_hdr *)sig; + const struct public_key *pk; + struct key *key; + int ret; + + if (siglen <= sizeof(*hdr)) + return -EBADMSG; + + siglen -= sizeof(*hdr); + + if (siglen != be16_to_cpu(hdr->sig_size)) + return -EBADMSG; + + if (hdr->hash_algo >= HASH_ALGO__LAST) + return -ENOPKG; + + key = request_asymmetric_key(keyring, be32_to_cpu(hdr->keyid)); + if (IS_ERR(key)) + return PTR_ERR(key); + + memset(&pks, 0, sizeof(pks)); + + pks.hash_algo = hash_algo_name[hdr->hash_algo]; + + pk = asymmetric_key_public_key(key); + pks.pkey_algo = pk->pkey_algo; + if (!strcmp(pk->pkey_algo, "rsa")) { + pks.encoding = "pkcs1"; + } else if (!strncmp(pk->pkey_algo, "ecdsa-", 6)) { + /* edcsa-nist-p192 etc. */ + pks.encoding = "x962"; + } else if (!strcmp(pk->pkey_algo, "ecrdsa") || + !strcmp(pk->pkey_algo, "sm2")) { + pks.encoding = "raw"; + } else { + ret = -ENOPKG; + goto out; + } + + pks.digest = (u8 *)data; + pks.digest_size = datalen; + pks.s = hdr->sig; + pks.s_size = siglen; + ret = verify_signature(key, &pks); +out: + key_put(key); + pr_debug("%s() = %d\n", __func__, ret); + return ret; +} + +/** + * integrity_kernel_module_request - prevent crypto-pkcs1pad(rsa,*) requests + * @kmod_name: kernel module name + * + * We have situation, when public_key_verify_signature() in case of RSA + * algorithm use alg_name to store internal information in order to + * construct an algorithm on the fly, but crypto_larval_lookup() will try + * to use alg_name in order to load kernel module with same name. + * Since we don't have any real "crypto-pkcs1pad(rsa,*)" kernel modules, + * we are safe to fail such module request from crypto_larval_lookup(). + * + * In this way we prevent modprobe execution during digsig verification + * and avoid possible deadlock if modprobe and/or it's dependencies + * also signed with digsig. + */ +int integrity_kernel_module_request(char *kmod_name) +{ + if (strncmp(kmod_name, "crypto-pkcs1pad(rsa,", 20) == 0) + return -EINVAL; + + return 0; +} |