[PATCH 10/12] nvmet: Implement basic In-Band Authentication
Sagi Grimberg
sagi at grimberg.me
Wed Sep 29 03:37:46 PDT 2021
On 9/28/21 9:03 AM, Hannes Reinecke wrote:
> Implement NVMe-oF In-Band authentication according to NVMe TPAR 8006.
> This patch adds three additional configfs entries 'dhchap_key', 'dhchap_ctrl_key',
> and 'dhchap_hash' to the 'host' configfs directory. The 'dhchap_key' and
> 'dhchap_ctrl_key' entries need to be in the ASCII format as specified in
> NVMe Base Specification v2.0 section 8.13.5.8 'Secret representation'.
> 'dhchap_hash' defaults to 'hmac(sha256)', and can be changed to switch to
> a different HMAC algorithm.
>
> Signed-off-by: Hannes Reinecke <hare at suse.de>
> ---
> drivers/nvme/target/Kconfig | 11 +
> drivers/nvme/target/Makefile | 1 +
> drivers/nvme/target/admin-cmd.c | 4 +
> drivers/nvme/target/auth.c | 345 ++++++++++++++++++
> drivers/nvme/target/configfs.c | 102 +++++-
> drivers/nvme/target/core.c | 8 +
> drivers/nvme/target/fabrics-cmd-auth.c | 466 +++++++++++++++++++++++++
> drivers/nvme/target/fabrics-cmd.c | 30 +-
> drivers/nvme/target/nvmet.h | 67 ++++
> 9 files changed, 1031 insertions(+), 3 deletions(-)
> create mode 100644 drivers/nvme/target/auth.c
> create mode 100644 drivers/nvme/target/fabrics-cmd-auth.c
>
> diff --git a/drivers/nvme/target/Kconfig b/drivers/nvme/target/Kconfig
> index 973561c93888..70f3c385fc9f 100644
> --- a/drivers/nvme/target/Kconfig
> +++ b/drivers/nvme/target/Kconfig
> @@ -83,3 +83,14 @@ config NVME_TARGET_TCP
> devices over TCP.
>
> If unsure, say N.
> +
> +config NVME_TARGET_AUTH
> + bool "NVMe over Fabrics In-band Authentication support"
> + depends on NVME_TARGET
> + select CRYPTO_HMAC
> + select CRYPTO_SHA256
> + select CRYPTO_SHA512
> + help
> + This enables support for NVMe over Fabrics In-band Authentication
> +
> + If unsure, say N.
> diff --git a/drivers/nvme/target/Makefile b/drivers/nvme/target/Makefile
> index 9837e580fa7e..c66820102493 100644
> --- a/drivers/nvme/target/Makefile
> +++ b/drivers/nvme/target/Makefile
> @@ -13,6 +13,7 @@ nvmet-y += core.o configfs.o admin-cmd.o fabrics-cmd.o \
> discovery.o io-cmd-file.o io-cmd-bdev.o
> nvmet-$(CONFIG_NVME_TARGET_PASSTHRU) += passthru.o
> nvmet-$(CONFIG_BLK_DEV_ZONED) += zns.o
> +nvmet-$(CONFIG_NVME_TARGET_AUTH) += fabrics-cmd-auth.o auth.o
> nvme-loop-y += loop.o
> nvmet-rdma-y += rdma.o
> nvmet-fc-y += fc.o
> diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
> index aa6d84d8848e..868d65c869cd 100644
> --- a/drivers/nvme/target/admin-cmd.c
> +++ b/drivers/nvme/target/admin-cmd.c
> @@ -1008,6 +1008,10 @@ u16 nvmet_parse_admin_cmd(struct nvmet_req *req)
>
> if (nvme_is_fabrics(cmd))
> return nvmet_parse_fabrics_cmd(req);
> +
> + if (unlikely(!nvmet_check_auth_status(req)))
> + return NVME_SC_AUTH_REQUIRED | NVME_SC_DNR;
> +
> if (nvmet_req_subsys(req)->type == NVME_NQN_DISC)
> return nvmet_parse_discovery_cmd(req);
>
> diff --git a/drivers/nvme/target/auth.c b/drivers/nvme/target/auth.c
> new file mode 100644
> index 000000000000..7247a7b97644
> --- /dev/null
> +++ b/drivers/nvme/target/auth.c
> @@ -0,0 +1,345 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * NVMe over Fabrics DH-HMAC-CHAP authentication.
> + * Copyright (c) 2020 Hannes Reinecke, SUSE Software Solutions.
> + * All rights reserved.
> + */
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/err.h>
> +#include <crypto/hash.h>
> +#include <linux/crc32.h>
> +#include <linux/base64.h>
> +#include <linux/ctype.h>
> +#include <linux/random.h>
> +#include <asm/unaligned.h>
> +
> +#include "nvmet.h"
> +#include "../host/auth.h"
> +
> +int nvmet_auth_set_host_key(struct nvmet_host *host, const char *secret)
> +{
> + if (sscanf(secret, "DHHC-1:%hhd:%*s", &host->dhchap_key_hash) != 1)
> + return -EINVAL;
> + if (host->dhchap_key_hash > 3) {
> + pr_warn("Invalid DH-HMAC-CHAP hash id %d\n",
> + host->dhchap_key_hash);
> + return -EINVAL;
> + }
> + if (host->dhchap_key_hash > 0) {
> + /* Validate selected hash algorithm */
> + const char *hmac = nvme_auth_hmac_name(host->dhchap_key_hash);
> +
> + if (!crypto_has_shash(hmac, 0, 0)) {
> + pr_err("DH-HMAC-CHAP hash %s unsupported\n", hmac);
> + host->dhchap_key_hash = -1;
> + return -ENOTSUPP;
> + }
> + /* Use this hash as default */
> + if (!host->dhchap_hash_id)
> + host->dhchap_hash_id = host->dhchap_key_hash;
> + }
> + host->dhchap_secret = kstrdup(secret, GFP_KERNEL);
> + if (!host->dhchap_secret)
> + return -ENOMEM;
> + /* Default to SHA256 */
> + if (!host->dhchap_hash_id)
> + host->dhchap_hash_id = NVME_AUTH_DHCHAP_SHA256;
> +
> + pr_debug("Using hash %s\n",
> + nvme_auth_hmac_name(host->dhchap_hash_id));
> + return 0;
> +}
> +
> +int nvmet_auth_set_ctrl_key(struct nvmet_host *host, const char *secret)
> +{
> + unsigned char dhchap_key_hash;
> +
> + if (sscanf(secret, "DHHC-1:%hhd:%*s", &dhchap_key_hash) != 1)
> + return -EINVAL;
> + if (dhchap_key_hash > 3) {
> + pr_warn("Invalid DH-HMAC-CHAP hash id %d\n",
> + dhchap_key_hash);
> + return -EINVAL;
> + }
> + if (dhchap_key_hash > 0) {
> + /* Validate selected hash algorithm */
> + const char *hmac = nvme_auth_hmac_name(dhchap_key_hash);
> +
> + if (!crypto_has_shash(hmac, 0, 0)) {
> + pr_err("DH-HMAC-CHAP hash %s unsupported\n", hmac);
> + return -ENOTSUPP;
> + }
> + }
> + host->dhchap_ctrl_secret = kstrdup(secret, GFP_KERNEL);
> + return host->dhchap_ctrl_secret ? 0 : -ENOMEM;
> +}
> +
> +int nvmet_setup_auth(struct nvmet_ctrl *ctrl)
> +{
> + int ret = 0;
> + struct nvmet_host_link *p;
> + struct nvmet_host *host = NULL;
> + const char *hash_name;
> +
> + down_read(&nvmet_config_sem);
> + if (ctrl->subsys->type == NVME_NQN_DISC)
> + goto out_unlock;
> +
> + if (ctrl->subsys->allow_any_host)
> + goto out_unlock;
> +
> + list_for_each_entry(p, &ctrl->subsys->hosts, entry) {
> + pr_debug("check %s\n", nvmet_host_name(p->host));
> + if (strcmp(nvmet_host_name(p->host), ctrl->hostnqn))
> + continue;
> + host = p->host;
> + break;
> + }
> + if (!host) {
> + pr_debug("host %s not found\n", ctrl->hostnqn);
> + ret = -EPERM;
> + goto out_unlock;
> + }
> + if (!host->dhchap_secret) {
> + pr_debug("No authentication provided\n");
> + goto out_unlock;
> + }
> +
> + if (ctrl->shash_tfm) {
> + if (host->dhchap_hash_id == ctrl->shash_id) {
> + pr_debug("Re-use existing hash ID %d\n",
> + ctrl->shash_id);
> + goto out_unlock;
> + }
> + crypto_free_shash(ctrl->shash_tfm);
> + ctrl->shash_tfm = NULL;
> + }
> +
> + hash_name = nvme_auth_hmac_name(host->dhchap_hash_id);
> + if (!hash_name) {
> + pr_warn("Hash ID %d invalid\n", host->dhchap_hash_id);
> + ret = -EINVAL;
> + goto out_unlock;
> + }
> + ctrl->shash_tfm = crypto_alloc_shash(hash_name, 0,
> + CRYPTO_ALG_ALLOCATES_MEMORY);
> + if (IS_ERR(ctrl->shash_tfm)) {
> + pr_err("failed to allocate shash %s\n", hash_name);
> + ret = PTR_ERR(ctrl->shash_tfm);
> + ctrl->shash_tfm = NULL;
> + goto out_unlock;
> + }
> + ctrl->shash_id = host->dhchap_hash_id;
> +
> + /* Skip the 'DHHC-1:XX:' prefix */
> + ctrl->dhchap_key = nvme_auth_extract_secret(host->dhchap_secret + 10,
> + &ctrl->dhchap_key_len);
> + if (IS_ERR(ctrl->dhchap_key)) {
> + ret = PTR_ERR(ctrl->dhchap_key);
> + pr_debug("failed to extract host key, error %d\n", ret);
> + ctrl->dhchap_key = NULL;
> + goto out_free_hash;
> + }
> + pr_debug("%s: using key %*ph\n", __func__,
> + (int)ctrl->dhchap_key_len, ctrl->dhchap_key);
> +
> + if (!host->dhchap_ctrl_secret)
> + goto out_unlock;
> +
> + ctrl->dhchap_ctrl_key = nvme_auth_extract_secret(host->dhchap_ctrl_secret + 10,
> + &ctrl->dhchap_ctrl_key_len);
> + if (IS_ERR(ctrl->dhchap_ctrl_key)) {
> + ret = PTR_ERR(ctrl->dhchap_ctrl_key);
> + pr_debug("failed to extract ctrl key, error %d\n", ret);
> + ctrl->dhchap_ctrl_key = NULL;
> + }
> +
> +out_free_hash:
> + if (ret) {
> + if (ctrl->dhchap_key) {
> + kfree_sensitive(ctrl->dhchap_key);
> + ctrl->dhchap_key = NULL;
> + }
> + crypto_free_shash(ctrl->shash_tfm);
> + ctrl->shash_tfm = NULL;
> + ctrl->shash_id = 0;
> + }
> +out_unlock:
> + up_read(&nvmet_config_sem);
> +
> + return ret;
> +}
> +
> +void nvmet_auth_sq_free(struct nvmet_sq *sq)
> +{
> + kfree(sq->dhchap_c1);
> + sq->dhchap_c1 = NULL;
> + kfree(sq->dhchap_c2);
> + sq->dhchap_c2 = NULL;
> + kfree(sq->dhchap_skey);
> + sq->dhchap_skey = NULL;
> +}
> +
> +void nvmet_destroy_auth(struct nvmet_ctrl *ctrl)
> +{
> + if (ctrl->shash_tfm) {
> + crypto_free_shash(ctrl->shash_tfm);
> + ctrl->shash_tfm = NULL;
> + ctrl->shash_id = 0;
> + }
> + if (ctrl->dhchap_key) {
> + kfree_sensitive(ctrl->dhchap_key);
> + ctrl->dhchap_key = NULL;
> + }
> + if (ctrl->dhchap_ctrl_key) {
> + kfree_sensitive(ctrl->dhchap_ctrl_key);
> + ctrl->dhchap_ctrl_key = NULL;
> + }
> +}
> +
> +bool nvmet_check_auth_status(struct nvmet_req *req)
> +{
> + if (req->sq->ctrl->shash_tfm &&
> + !req->sq->authenticated)
> + return false;
> + return true;
> +}
> +
> +int nvmet_auth_host_hash(struct nvmet_req *req, u8 *response,
> + unsigned int shash_len)
> +{
> + struct nvmet_ctrl *ctrl = req->sq->ctrl;
> + SHASH_DESC_ON_STACK(shash, ctrl->shash_tfm);
> + u8 *challenge = req->sq->dhchap_c1, *host_response;
> + u8 buf[4];
> + int ret;
> +
> + if (shash_len != ctrl->dhchap_key_len)
> + return -EINVAL;
Is this condition correct? the shash_len is sent by the host
and afaict the host is setting it by what the controller sent
in the challenge. the ctrl->dhchap_key_len is taken from
nvme_auth_extract_secret.
In other words, if the nvmet host is set to use hmac(sha512) then
authentication fails, regardless of the key.
I think we need a set of blktests to sanity test different hash,
dh_group, secrect-length, dhchap_key and dhchap_ctrl_key combinations.
The code is not trivial to follow with the different transformations,
hashes etc...
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