nvme-auth: Diffie-Hellman key exchange support

Implement Diffie-Hellman key exchange using FFDHE groups
for NVMe In-Band Authentication.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/common/auth.c

@@ -295,6 +295,159 @@ u8 *nvme_auth_transform_key(struct nvme_dhchap_key *key, char *nqn)
 }
 EXPORT_SYMBOL_GPL(nvme_auth_transform_key);
 
+static int nvme_auth_hash_skey(int hmac_id, u8 *skey, size_t skey_len, u8 *hkey)
+{
+	const char *digest_name;
+	struct crypto_shash *tfm;
+	int ret;
+
+	digest_name = nvme_auth_digest_name(hmac_id);
+	if (!digest_name) {
+		pr_debug("%s: failed to get digest for %d\n", __func__,
+			 hmac_id);
+		return -EINVAL;
+	}
+	tfm = crypto_alloc_shash(digest_name, 0, 0);
+	if (IS_ERR(tfm))
+		return -ENOMEM;
+
+	ret = crypto_shash_tfm_digest(tfm, skey, skey_len, hkey);
+	if (ret < 0)
+		pr_debug("%s: Failed to hash digest len %zu\n", __func__,
+			 skey_len);
+
+	crypto_free_shash(tfm);
+	return ret;
+}
+
+int nvme_auth_augmented_challenge(u8 hmac_id, u8 *skey, size_t skey_len,
+		u8 *challenge, u8 *aug, size_t hlen)
+{
+	struct crypto_shash *tfm;
+	struct shash_desc *desc;
+	u8 *hashed_key;
+	const char *hmac_name;
+	int ret;
+
+	hashed_key = kmalloc(hlen, GFP_KERNEL);
+	if (!hashed_key)
+		return -ENOMEM;
+
+	ret = nvme_auth_hash_skey(hmac_id, skey,
+				  skey_len, hashed_key);
+	if (ret < 0)
+		goto out_free_key;
+
+	hmac_name = nvme_auth_hmac_name(hmac_id);
+	if (!hmac_name) {
+		pr_warn("%s: invalid hash algoritm %d\n",
+			__func__, hmac_id);
+		ret = -EINVAL;
+		goto out_free_key;
+	}
+
+	tfm = crypto_alloc_shash(hmac_name, 0, 0);
+	if (IS_ERR(tfm)) {
+		ret = PTR_ERR(tfm);
+		goto out_free_key;
+	}
+
+	desc = kmalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
+		       GFP_KERNEL);
+	if (!desc) {
+		ret = -ENOMEM;
+		goto out_free_hash;
+	}
+	desc->tfm = tfm;
+
+	ret = crypto_shash_setkey(tfm, hashed_key, hlen);
+	if (ret)
+		goto out_free_desc;
+
+	ret = crypto_shash_init(desc);
+	if (ret)
+		goto out_free_desc;
+
+	ret = crypto_shash_update(desc, challenge, hlen);
+	if (ret)
+		goto out_free_desc;
+
+	ret = crypto_shash_final(desc, aug);
+out_free_desc:
+	kfree_sensitive(desc);
+out_free_hash:
+	crypto_free_shash(tfm);
+out_free_key:
+	kfree_sensitive(hashed_key);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nvme_auth_augmented_challenge);
+
+int nvme_auth_gen_privkey(struct crypto_kpp *dh_tfm, u8 dh_gid)
+{
+	int ret;
+
+	ret = crypto_kpp_set_secret(dh_tfm, NULL, 0);
+	if (ret)
+		pr_debug("failed to set private key, error %d\n", ret);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nvme_auth_gen_privkey);
+
+int nvme_auth_gen_pubkey(struct crypto_kpp *dh_tfm,
+		u8 *host_key, size_t host_key_len)
+{
+	struct kpp_request *req;
+	struct crypto_wait wait;
+	struct scatterlist dst;
+	int ret;
+
+	req = kpp_request_alloc(dh_tfm, GFP_KERNEL);
+	if (!req)
+		return -ENOMEM;
+
+	crypto_init_wait(&wait);
+	kpp_request_set_input(req, NULL, 0);
+	sg_init_one(&dst, host_key, host_key_len);
+	kpp_request_set_output(req, &dst, host_key_len);
+	kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+				 crypto_req_done, &wait);
+
+	ret = crypto_wait_req(crypto_kpp_generate_public_key(req), &wait);
+	kpp_request_free(req);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nvme_auth_gen_pubkey);
+
+int nvme_auth_gen_shared_secret(struct crypto_kpp *dh_tfm,
+		u8 *ctrl_key, size_t ctrl_key_len,
+		u8 *sess_key, size_t sess_key_len)
+{
+	struct kpp_request *req;
+	struct crypto_wait wait;
+	struct scatterlist src, dst;
+	int ret;
+
+	req = kpp_request_alloc(dh_tfm, GFP_KERNEL);
+	if (!req)
+		return -ENOMEM;
+
+	crypto_init_wait(&wait);
+	sg_init_one(&src, ctrl_key, ctrl_key_len);
+	kpp_request_set_input(req, &src, ctrl_key_len);
+	sg_init_one(&dst, sess_key, sess_key_len);
+	kpp_request_set_output(req, &dst, sess_key_len);
+	kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
+				 crypto_req_done, &wait);
+
+	ret = crypto_wait_req(crypto_kpp_compute_shared_secret(req), &wait);
+
+	kpp_request_free(req);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nvme_auth_gen_shared_secret);
+
 int nvme_auth_generate_key(u8 *secret, struct nvme_dhchap_key **ret_key)
 {
 	struct nvme_dhchap_key *key;

drivers/nvme/host/Kconfig

@@ -100,6 +100,8 @@ config NVME_AUTH
 	select CRYPTO_HMAC
 	select CRYPTO_SHA256
 	select CRYPTO_SHA512
+	select CRYPTO_DH
+	select CRYPTO_DH_RFC7919_GROUPS
 	help
 	  This provides support for NVMe over Fabrics In-Band Authentication.