Received-SPF: pass (google.com: domain of linux-crypto-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH 10/12] nvmet: Implement basic In-Band Authentication
To:     Sagi Grimberg <sagi@grimberg.me>
Cc:     Christoph Hellwig <hch@lst.de>, Keith Busch <keith.busch@wdc.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S . Miller" <davem@davemloft.net>,
        linux-nvme@lists.infradead.org, linux-crypto@vger.kernel.org
References: <20210928060356.27338-1-hare@suse.de>
 <20210928060356.27338-11-hare@suse.de>
 <d8827017-f8a7-c1fc-1950-8ac6c5997103@grimberg.me>
 <d1f4cd0c-1d53-6eff-83e2-d1b4d04b7221@suse.de>
 <e876b96a-e24b-d0de-0c62-d4345c4f8714@grimberg.me>
From:   Hannes Reinecke <hare@suse.de>
Message-ID: <c1c90d31-a4c3-ab13-2f29-55a103715ef8@suse.de>
Date:   Wed, 29 Sep 2021 16:32:34 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.12.0
MIME-Version: 1.0
In-Reply-To: <e876b96a-e24b-d0de-0c62-d4345c4f8714@grimberg.me>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Precedence: bulk

On 9/29/21 2:36 PM, Sagi Grimberg wrote:
> 
> 
> On 9/29/21 3:26 PM, Hannes Reinecke wrote:
>> On 9/29/21 12:37 PM, Sagi Grimberg wrote:
>>>
>>>
>>> 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@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.
>>>
>> Ideally, but shash_len is actually sent by the host, so it _might_ be
>> different (as it's picked up from the command sent by the host).
>>
>>> In other words, if the nvmet host is set to use hmac(sha512) then
>>> authentication fails, regardless of the key.
>>>
>> Nope. The hash algorithm is figured out the 'negotiation' step,
>> so the host _should_ have set the correct hash length.
>> But as this is networking you should be validating each field in the
>> received packet to ensure it matches what you expect.
> 
> On the target:
> # grep -r ''
> /sys/kernel/config/nvmet/hosts/nqn.2014-08.org.nvmexpress\:uuid\:b73ff014-2723-4114-aa8d-2f784ecba4f4/
> 
> /sys/kernel/config/nvmet/hosts/nqn.2014-08.org.nvmexpress:uuid:b73ff014-2723-4114-aa8d-2f784ecba4f4/dhchap_dhgroup:null
> 
> /sys/kernel/config/nvmet/hosts/nqn.2014-08.org.nvmexpress:uuid:b73ff014-2723-4114-aa8d-2f784ecba4f4/dhchap_hash:hmac(sha512)
> 
> /sys/kernel/config/nvmet/hosts/nqn.2014-08.org.nvmexpress:uuid:b73ff014-2723-4114-aa8d-2f784ecba4f4/dhchap_ctrl_key:
> 
> /sys/kernel/config/nvmet/hosts/nqn.2014-08.org.nvmexpress:uuid:b73ff014-2723-4114-aa8d-2f784ecba4f4/dhchap_key:DHHC-1:03:KUwVlIUo627Pn05W/lRL2XD57kzIs1yZzJWdd2vgZJUC74kr:
> 
> 
> On the host:
> # ./nvme connect-all
> --dhchap-secret="DHHC-1:03:KUwVlIUo627Pn05W/lRL2XD57kzIs1yZzJWdd2vgZJUC74kr:"
> 
> failed to connect controller, error 5
> 
> On the target dmesg:
> [ 8695.716117] nvmet: creating controller 1 for subsystem
> nqn.2014-08.org.nvmexpress.discovery for NQN
> nqn.2014-08.org.nvmexpress:uuid:b73ff014-2723-4114-aa8d-2f784ecba4f4.
> [ 8695.749996] nvmet: creating controller 2 for subsystem testnqn1 for
> NQN nqn.2014-08.org.nvmexpress:uuid:b73ff014-2723-4114-aa8d-2f784ecba4f4
> with DH-HMAC-CHAP.
> [ 8695.755361] nvmet: ctrl 2 qid 0 failure1 (1)
> [ 8695.755449] nvmet: ctrl 2 fatal error occurred!
> 
> On the host dmesg:
> [ 8781.616712] nvme nvme1: new ctrl: NQN
> "nqn.2014-08.org.nvmexpress.discovery", addr 192.168.123.1:8009
> [ 8781.637954] nvme nvme2: qid 0: authentication failed
> [ 8781.638084] nvme nvme2: failed to connect queue: 0 ret=401
> 
> If I change the dhchap_hash to hmac(sha256) authentication succeeds.
> The failure with hmac(sha512) comes from the above condition as the
> host is sending key length 64 and nvmet is expecting 32.

A-ha. That shouldn't have happened; selecting the hash on the target was
_supposed_ to be reflected to the host.

You did mention something about blocktests; guess I'll need to bite the
bullet and actually implement something there.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@suse.de			                  +49 911 74053 688
SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), GF: Felix Imendörffer