[PATCH 5/9] nvme-auth: Diffie-Hellman key exchange support

Hannes Reinecke
2022-05-27T08:06:12Z

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>
---
drivers/nvme/host/Kconfig | 1 +
drivers/nvme/host/auth.c | 364 +++++++++++++++++++++++++++++++++++++-
drivers/nvme/host/auth.h | 8 +
3 files changed, 367 insertions(+), 6 deletions(-)

diff --git a/drivers/nvme/host/Kconfig b/drivers/nvme/host/Kconfig
index dd0e91fb0615..4a45dac52f7e 100644
--- a/drivers/nvme/host/Kconfig
+++ b/drivers/nvme/host/Kconfig
@@ -98,6 +98,7 @@ config NVME_AUTH
select CRYPTO_HMAC
select CRYPTO_SHA256
select CRYPTO_SHA512
+ select CRYPTO_DH_RFC7919_GROUPS
help
This provides support for NVMe over Fabrics In-Band Authentication.

diff --git a/drivers/nvme/host/auth.c b/drivers/nvme/host/auth.c
index 5ae607defb94..c6ed33293525 100644
--- a/drivers/nvme/host/auth.c
+++ b/drivers/nvme/host/auth.c
@@ -21,6 +21,7 @@ struct nvme_dhchap_queue_context {
struct work_struct auth_work;
struct nvme_ctrl *ctrl;
struct crypto_shash *shash_tfm;
+ struct crypto_kpp *dh_tfm;
void *buf;
size_t buf_size;
int qid;
@@ -36,6 +37,12 @@ struct nvme_dhchap_queue_context {
u8 c2[64];
u8 response[64];
u8 *host_response;
+ u8 *ctrl_key;
+ int ctrl_key_len;
+ u8 *host_key;
+ int host_key_len;
+ u8 *sess_key;
+ int sess_key_len;
};

u32 nvme_auth_get_seqnum(void)
@@ -62,6 +69,18 @@ static struct nvme_auth_dhgroup_map {
} dhgroup_map[] = {
[NVME_AUTH_DHGROUP_NULL] = {
.name = "null", .kpp = "null" },
+#ifdef CONFIG_CRYPTO_DH_RFC7919_GROUPS
+ [NVME_AUTH_DHGROUP_2048] = {
+ .name = "ffdhe2048", .kpp = "ffdhe2048(dh)" },
+ [NVME_AUTH_DHGROUP_3072] = {
+ .name = "ffdhe3072", .kpp = "ffdhe3072(dh)" },
+ [NVME_AUTH_DHGROUP_4096] = {
+ .name = "ffdhe4096", .kpp = "ffdhe4096(dh)" },
+ [NVME_AUTH_DHGROUP_6144] = {
+ .name = "ffdhe6144", .kpp = "ffdhe6144(dh)" },
+ [NVME_AUTH_DHGROUP_8192] = {
+ .name = "ffdhe8192", .kpp = "ffdhe8192(dh)" },
+#endif
};

const char *nvme_auth_dhgroup_name(u8 dhgroup_id)
@@ -316,6 +335,159 @@ 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);
+
#define nvme_auth_flags_from_qid(qid) \
(qid == 0) ? 0 : BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_RESERVED
#define nvme_auth_queue_from_qid(ctrl, qid) \
@@ -418,6 +590,7 @@ static int nvme_auth_process_dhchap_challenge(struct nvme_ctrl *ctrl,
struct nvmf_auth_dhchap_challenge_data *data = chap->buf;
u16 dhvlen = le16_to_cpu(data->dhvlen);
size_t size = sizeof(*data) + data->hl + dhvlen;
+ const char *gid_name = nvme_auth_dhgroup_name(data->dhgid);
const char *hmac_name, *kpp_name;

if (chap->buf_size < size) {
@@ -488,15 +661,54 @@ static int nvme_auth_process_dhchap_challenge(struct nvme_ctrl *ctrl,
"qid %d: invalid DH group id %d\n",
chap->qid, data->dhgid);
chap->status = NVME_AUTH_DHCHAP_FAILURE_DHGROUP_UNUSABLE;
+ /* Leave previous dh_tfm intact */
return NVME_SC_AUTH_REQUIRED;
}

+ /* Clear host and controller key to avoid accidental reuse */
+ kfree_sensitive(chap->host_key);
+ chap->host_key = NULL;
+ chap->host_key_len = 0;
+ kfree_sensitive(chap->ctrl_key);
+ chap->ctrl_key = NULL;
+ chap->ctrl_key_len = 0;
+
+ if (chap->dhgroup_id == data->dhgid &&
+ (data->dhgid == NVME_AUTH_DHGROUP_NULL || chap->dh_tfm)) {
+ dev_dbg(ctrl->device,
+ "qid %d: reuse existing DH group %s\n",
+ chap->qid, gid_name);
+ goto skip_kpp;
+ }
+
+ /* Reset dh_tfm if it can't be reused */
+ if (chap->dh_tfm) {
+ crypto_free_kpp(chap->dh_tfm);
+ chap->dh_tfm = NULL;
+ }
+
if (data->dhgid != NVME_AUTH_DHGROUP_NULL) {
- dev_warn(ctrl->device,
- "qid %d: unsupported DH group %s\n",
- chap->qid, kpp_name);
- chap->status = NVME_AUTH_DHCHAP_FAILURE_DHGROUP_UNUSABLE;
- return NVME_SC_AUTH_REQUIRED;
+ if (dhvlen == 0) {
+ dev_warn(ctrl->device,
+ "qid %d: empty DH value\n",
+ chap->qid);
+ chap->status = NVME_AUTH_DHCHAP_FAILURE_DHGROUP_UNUSABLE;
+ return NVME_SC_INVALID_FIELD;
+ }
+
+ chap->dh_tfm = crypto_alloc_kpp(kpp_name, 0, 0);
+ if (IS_ERR(chap->dh_tfm)) {
+ int ret = PTR_ERR(chap->dh_tfm);
+
+ dev_warn(ctrl->device,
+ "qid %d: error %d initializing DH group %s\n",
+ chap->qid, ret, gid_name);
+ chap->status = NVME_AUTH_DHCHAP_FAILURE_DHGROUP_UNUSABLE;
+ chap->dh_tfm = NULL;
+ return NVME_SC_AUTH_REQUIRED;
+ }
+ dev_dbg(ctrl->device, "qid %d: selected DH group %s\n",
+ chap->qid, gid_name);
} else if (dhvlen != 0) {
dev_warn(ctrl->device,
"qid %d: invalid DH value for NULL DH\n",
@@ -506,8 +718,21 @@ static int nvme_auth_process_dhchap_challenge(struct nvme_ctrl *ctrl,
}
chap->dhgroup_id = data->dhgid;

+skip_kpp:
chap->s1 = le32_to_cpu(data->seqnum);
memcpy(chap->c1, data->cval, chap->hash_len);
+ if (dhvlen) {
+ chap->ctrl_key = kmalloc(dhvlen, GFP_KERNEL);
+ if (!chap->ctrl_key) {
+ chap->status = NVME_AUTH_DHCHAP_FAILURE_FAILED;
+ return NVME_SC_AUTH_REQUIRED;
+ }
+ chap->ctrl_key_len = dhvlen;
+ memcpy(chap->ctrl_key, data->cval + chap->hash_len,
+ dhvlen);
+ dev_dbg(ctrl->device, "ctrl public key %*ph\n",
+ (int)chap->ctrl_key_len, chap->ctrl_key);
+ }

return 0;
}
@@ -520,6 +745,9 @@ static int nvme_auth_set_dhchap_reply_data(struct nvme_ctrl *ctrl,

size += 2 * chap->hash_len;

+ if (chap->host_key_len)
+ size += chap->host_key_len;
+
if (chap->buf_size < size) {
chap->status = NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
return -EINVAL;
@@ -530,7 +758,7 @@ static int nvme_auth_set_dhchap_reply_data(struct nvme_ctrl *ctrl,
data->auth_id = NVME_AUTH_DHCHAP_MESSAGE_REPLY;
data->t_id = cpu_to_le16(chap->transaction);
data->hl = chap->hash_len;
- data->dhvlen = 0;
+ data->dhvlen = cpu_to_le16(chap->host_key_len);
memcpy(data->rval, chap->response, chap->hash_len);
if (ctrl->opts->dhchap_ctrl_secret) {
get_random_bytes(chap->c2, chap->hash_len);
@@ -545,6 +773,14 @@ static int nvme_auth_set_dhchap_reply_data(struct nvme_ctrl *ctrl,
chap->s2 = 0;
}
data->seqnum = cpu_to_le32(chap->s2);
+ if (chap->host_key_len) {
+ dev_dbg(ctrl->device, "%s: qid %d host public key %*ph\n",
+ __func__, chap->qid,
+ chap->host_key_len, chap->host_key);
+ memcpy(data->rval + 2 * chap->hash_len, chap->host_key,
+ chap->host_key_len);
+ }
+
return size;
}

@@ -662,6 +898,21 @@ static int nvme_auth_dhchap_setup_host_response(struct nvme_ctrl *ctrl,
goto out;
}

+ if (chap->dh_tfm) {
+ challenge = kmalloc(chap->hash_len, GFP_KERNEL);
+ if (!challenge) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ ret = nvme_auth_augmented_challenge(chap->hash_id,
+ chap->sess_key,
+ chap->sess_key_len,
+ chap->c1, challenge,
+ chap->hash_len);
+ if (ret)
+ goto out;
+ }
+
shash->tfm = chap->shash_tfm;
ret = crypto_shash_init(shash);
if (ret)
@@ -724,6 +975,20 @@ static int nvme_auth_dhchap_setup_ctrl_response(struct nvme_ctrl *ctrl,
goto out;
}

+ if (chap->dh_tfm) {
+ challenge = kmalloc(chap->hash_len, GFP_KERNEL);
+ if (!challenge) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ ret = nvme_auth_augmented_challenge(chap->hash_id,
+ chap->sess_key,
+ chap->sess_key_len,
+ chap->c2, challenge,
+ chap->hash_len);
+ if (ret)
+ goto out;
+ }
dev_dbg(ctrl->device, "%s: qid %d ctrl response seq %u transaction %d\n",
__func__, chap->qid, chap->s2, chap->transaction);
dev_dbg(ctrl->device, "%s: qid %d challenge %*ph\n",
@@ -796,8 +1061,81 @@ int nvme_auth_generate_key(u8 *secret, struct nvme_dhchap_key **ret_key)
}
EXPORT_SYMBOL_GPL(nvme_auth_generate_key);

+static int nvme_auth_dhchap_exponential(struct nvme_ctrl *ctrl,
+ struct nvme_dhchap_queue_context *chap)
+{
+ int ret;
+
+ if (chap->host_key && chap->host_key_len) {
+ dev_dbg(ctrl->device,
+ "qid %d: reusing host key\n", chap->qid);
+ goto gen_sesskey;
+ }
+ ret = nvme_auth_gen_privkey(chap->dh_tfm, chap->dhgroup_id);
+ if (ret < 0) {
+ chap->status = NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
+ return ret;
+ }
+
+ chap->host_key_len = crypto_kpp_maxsize(chap->dh_tfm);
+
+ chap->host_key = kzalloc(chap->host_key_len, GFP_KERNEL);
+ if (!chap->host_key) {
+ chap->host_key_len = 0;
+ chap->status = NVME_AUTH_DHCHAP_FAILURE_FAILED;
+ return -ENOMEM;
+ }
+ ret = nvme_auth_gen_pubkey(chap->dh_tfm,
+ chap->host_key, chap->host_key_len);
+ if (ret) {
+ dev_dbg(ctrl->device,
+ "failed to generate public key, error %d\n", ret);
+ kfree(chap->host_key);
+ chap->host_key = NULL;
+ chap->host_key_len = 0;
+ chap->status = NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
+ return ret;
+ }
+
+gen_sesskey:
+ chap->sess_key_len = chap->host_key_len;
+ chap->sess_key = kmalloc(chap->sess_key_len, GFP_KERNEL);
+ if (!chap->sess_key) {
+ chap->sess_key_len = 0;
+ chap->status = NVME_AUTH_DHCHAP_FAILURE_FAILED;
+ return -ENOMEM;
+ }
+
+ ret = nvme_auth_gen_shared_secret(chap->dh_tfm,
+ chap->ctrl_key, chap->ctrl_key_len,
+ chap->sess_key, chap->sess_key_len);
+ if (ret) {
+ dev_dbg(ctrl->device,
+ "failed to generate shared secret, error %d\n", ret);
+ kfree_sensitive(chap->sess_key);
+ chap->sess_key = NULL;
+ chap->sess_key_len = 0;
+ chap->status = NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
+ return ret;
+ }
+ dev_dbg(ctrl->device, "shared secret %*ph\n",
+ (int)chap->sess_key_len, chap->sess_key);
+ return 0;
+}
+
static void __nvme_auth_reset(struct nvme_dhchap_queue_context *chap)
{
+ kfree_sensitive(chap->host_response);
+ chap->host_response = NULL;
+ kfree_sensitive(chap->host_key);
+ chap->host_key = NULL;
+ chap->host_key_len = 0;
+ kfree_sensitive(chap->ctrl_key);
+ chap->ctrl_key = NULL;
+ chap->ctrl_key_len = 0;
+ kfree_sensitive(chap->sess_key);
+ chap->sess_key = NULL;
+ chap->sess_key_len = 0;
chap->status = 0;
chap->error = 0;
chap->s1 = 0;
@@ -812,6 +1150,11 @@ static void __nvme_auth_free(struct nvme_dhchap_queue_context *chap)
__nvme_auth_reset(chap);
if (chap->shash_tfm)
crypto_free_shash(chap->shash_tfm);
+ if (chap->dh_tfm)
+ crypto_free_kpp(chap->dh_tfm);
+ kfree_sensitive(chap->ctrl_key);
+ kfree_sensitive(chap->host_key);
+ kfree_sensitive(chap->sess_key);
kfree_sensitive(chap->host_response);
kfree(chap->buf);
kfree(chap);
@@ -869,6 +1212,15 @@ static void __nvme_auth_work(struct work_struct *work)
goto fail2;
}

+ if (chap->ctrl_key_len) {
+ dev_dbg(ctrl->device,
+ "%s: qid %d DH exponential\n",
+ __func__, chap->qid);
+ ret = nvme_auth_dhchap_exponential(ctrl, chap);
+ if (ret)
+ goto fail2;
+ }
+
dev_dbg(ctrl->device, "%s: qid %d host response\n",
__func__, chap->qid);
ret = nvme_auth_dhchap_setup_host_response(ctrl, chap);
diff --git a/drivers/nvme/host/auth.h b/drivers/nvme/host/auth.h
index 73d6ec63a5c8..98dda358cc3f 100644
--- a/drivers/nvme/host/auth.h
+++ b/drivers/nvme/host/auth.h
@@ -28,5 +28,13 @@ struct nvme_dhchap_key *nvme_auth_extract_key(unsigned char *secret,
u8 key_hash);
void nvme_auth_free_key(struct nvme_dhchap_key *key);
u8 *nvme_auth_transform_key(struct nvme_dhchap_key *key, char *nqn);
+int nvme_auth_augmented_challenge(u8 hmac_id, u8 *skey, size_t skey_len,
+ u8 *challenge, u8 *aug, size_t hlen);
+int nvme_auth_gen_privkey(struct crypto_kpp *dh_tfm, u8 dh_gid);
+int nvme_auth_gen_pubkey(struct crypto_kpp *dh_tfm,
+ u8 *host_key, size_t host_key_len);
+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);

#endif /* _NVME_AUTH_H */
--
2.29.2