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-rw-r--r--security/integrity/digsig_asymmetric.c156
1 files changed, 156 insertions, 0 deletions
diff --git a/security/integrity/digsig_asymmetric.c b/security/integrity/digsig_asymmetric.c
new file mode 100644
index 000000000..a662024b4
--- /dev/null
+++ b/security/integrity/digsig_asymmetric.c
@@ -0,0 +1,156 @@
+// 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;
+ 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];
+ switch (hdr->hash_algo) {
+ case HASH_ALGO_STREEBOG_256:
+ case HASH_ALGO_STREEBOG_512:
+ /* EC-RDSA and Streebog should go together. */
+ pks.pkey_algo = "ecrdsa";
+ pks.encoding = "raw";
+ break;
+ case HASH_ALGO_SM3_256:
+ /* SM2 and SM3 should go together. */
+ pks.pkey_algo = "sm2";
+ pks.encoding = "raw";
+ break;
+ default:
+ pks.pkey_algo = "rsa";
+ pks.encoding = "pkcs1";
+ break;
+ }
+ pks.digest = (u8 *)data;
+ pks.digest_size = datalen;
+ pks.s = hdr->sig;
+ pks.s_size = siglen;
+ ret = verify_signature(key, &pks);
+ 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;
+}