[PATCH 11/12] nvmet-auth: Diffie-Hellman key exchange support
Hannes Reinecke
hare at suse.de
Mon Sep 27 23:03:55 PDT 2021
Implement Diffie-Hellman key exchange using FFDHE groups for NVMe
In-Band Authentication.
This patch adds a new host configfs attribute 'dhchap_dhgroup' to
select the FFDHE group to use.
Signed-off-by: Hannes Reinecke <hare at suse.de>
---
drivers/nvme/target/Kconfig | 1 +
drivers/nvme/target/auth.c | 148 ++++++++++++++++++++++++-
drivers/nvme/target/configfs.c | 31 ++++++
drivers/nvme/target/fabrics-cmd-auth.c | 31 +++++-
drivers/nvme/target/nvmet.h | 6 +
5 files changed, 209 insertions(+), 8 deletions(-)
diff --git a/drivers/nvme/target/Kconfig b/drivers/nvme/target/Kconfig
index 70f3c385fc9f..2e41d70fd881 100644
--- a/drivers/nvme/target/Kconfig
+++ b/drivers/nvme/target/Kconfig
@@ -90,6 +90,7 @@ config NVME_TARGET_AUTH
select CRYPTO_HMAC
select CRYPTO_SHA256
select CRYPTO_SHA512
+ select CRYPTO_FFDHE
help
This enables support for NVMe over Fabrics In-band Authentication
diff --git a/drivers/nvme/target/auth.c b/drivers/nvme/target/auth.c
index 7247a7b97644..274b199bb6d7 100644
--- a/drivers/nvme/target/auth.c
+++ b/drivers/nvme/target/auth.c
@@ -77,6 +77,71 @@ int nvmet_auth_set_ctrl_key(struct nvmet_host *host, const char *secret)
return host->dhchap_ctrl_secret ? 0 : -ENOMEM;
}
+int nvmet_setup_dhgroup(struct nvmet_ctrl *ctrl, int dhgroup_id)
+{
+ struct nvmet_host_link *p;
+ struct nvmet_host *host = NULL;
+ const char *dhgroup_kpp;
+ int ret = -ENOTSUPP;
+
+ if (dhgroup_id == NVME_AUTH_DHCHAP_DHGROUP_NULL)
+ return 0;
+
+ down_read(&nvmet_config_sem);
+ if (ctrl->subsys->type == NVME_NQN_DISC)
+ goto out_unlock;
+
+ list_for_each_entry(p, &ctrl->subsys->hosts, entry) {
+ 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 = -ENXIO;
+ goto out_unlock;
+ }
+
+ if (host->dhchap_dhgroup_id != dhgroup_id) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+ if (ctrl->dh_tfm) {
+ if (ctrl->dh_gid == dhgroup_id) {
+ pr_debug("reuse existing DH group %d\n", dhgroup_id);
+ ret = 0;
+ } else {
+ pr_debug("DH group mismatch (selected %d, requested %d)\n",
+ ctrl->dh_gid, dhgroup_id);
+ ret = -EINVAL;
+ }
+ goto out_unlock;
+ }
+
+ dhgroup_kpp = nvme_auth_dhgroup_kpp(dhgroup_id);
+ if (!dhgroup_kpp) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+ ctrl->dh_tfm = crypto_alloc_kpp(dhgroup_kpp, 0, 0);
+ if (IS_ERR(ctrl->dh_tfm)) {
+ pr_debug("failed to setup DH group %d, err %ld\n",
+ dhgroup_id, PTR_ERR(ctrl->dh_tfm));
+ ret = PTR_ERR(ctrl->dh_tfm);
+ ctrl->dh_tfm = NULL;
+ } else {
+ ctrl->dh_gid = dhgroup_id;
+ ctrl->dh_keysize = nvme_auth_dhgroup_pubkey_size(dhgroup_id);
+ ret = 0;
+ }
+
+out_unlock:
+ up_read(&nvmet_config_sem);
+
+ return ret;
+}
+
int nvmet_setup_auth(struct nvmet_ctrl *ctrl)
{
int ret = 0;
@@ -190,6 +255,11 @@ void nvmet_destroy_auth(struct nvmet_ctrl *ctrl)
ctrl->shash_tfm = NULL;
ctrl->shash_id = 0;
}
+ if (ctrl->dh_tfm) {
+ crypto_free_kpp(ctrl->dh_tfm);
+ ctrl->dh_tfm = NULL;
+ ctrl->dh_gid = 0;
+ }
if (ctrl->dhchap_key) {
kfree_sensitive(ctrl->dhchap_key);
ctrl->dhchap_key = NULL;
@@ -232,8 +302,18 @@ int nvmet_auth_host_hash(struct nvmet_req *req, u8 *response,
return ret;
}
if (ctrl->dh_gid != NVME_AUTH_DHCHAP_DHGROUP_NULL) {
- ret = -ENOTSUPP;
- goto out;
+ challenge = kmalloc(shash_len, GFP_KERNEL);
+ if (!challenge) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ ret = nvme_auth_augmented_challenge(ctrl->shash_id,
+ req->sq->dhchap_skey,
+ req->sq->dhchap_skey_len,
+ req->sq->dhchap_c1,
+ challenge, shash_len);
+ if (ret)
+ goto out;
}
shash->tfm = ctrl->shash_tfm;
@@ -300,8 +380,18 @@ int nvmet_auth_ctrl_hash(struct nvmet_req *req, u8 *response,
return ret;
}
if (ctrl->dh_gid != NVME_AUTH_DHCHAP_DHGROUP_NULL) {
- ret = -ENOTSUPP;
- goto out;
+ challenge = kmalloc(shash_len, GFP_KERNEL);
+ if (!challenge) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ ret = nvme_auth_augmented_challenge(ctrl->shash_id,
+ req->sq->dhchap_skey,
+ req->sq->dhchap_skey_len,
+ req->sq->dhchap_c2,
+ challenge, shash_len);
+ if (ret)
+ goto out;
}
shash->tfm = ctrl->shash_tfm;
@@ -343,3 +433,53 @@ int nvmet_auth_ctrl_hash(struct nvmet_req *req, u8 *response,
kfree_sensitive(ctrl_response);
return 0;
}
+
+int nvmet_auth_ctrl_exponential(struct nvmet_req *req,
+ u8 *buf, int buf_size)
+{
+ struct nvmet_ctrl *ctrl = req->sq->ctrl;
+ int ret;
+
+ if (!ctrl->dh_tfm) {
+ pr_warn("No DH algorithm!\n");
+ return -ENOKEY;
+ }
+ ret = nvme_auth_gen_pubkey(ctrl->dh_tfm, buf, buf_size);
+ if (ret == -EOVERFLOW) {
+ pr_debug("public key buffer too small, need %d is %d\n",
+ crypto_kpp_maxsize(ctrl->dh_tfm), buf_size);
+ ret = -ENOKEY;
+ } else if (ret) {
+ pr_debug("failed to generate public key, err %d\n", ret);
+ ret = -ENOKEY;
+ } else
+ pr_debug("%s: ctrl public key %*ph\n", __func__,
+ (int)buf_size, buf);
+
+ return ret;
+}
+
+int nvmet_auth_ctrl_sesskey(struct nvmet_req *req,
+ u8 *pkey, int pkey_size)
+{
+ struct nvmet_ctrl *ctrl = req->sq->ctrl;
+ int ret;
+
+ req->sq->dhchap_skey_len =
+ nvme_auth_dhgroup_privkey_size(ctrl->dh_gid);
+ req->sq->dhchap_skey = kzalloc(req->sq->dhchap_skey_len, GFP_KERNEL);
+ if (!req->sq->dhchap_skey)
+ return -ENOMEM;
+ ret = nvme_auth_gen_shared_secret(ctrl->dh_tfm,
+ pkey, pkey_size,
+ req->sq->dhchap_skey,
+ req->sq->dhchap_skey_len);
+ if (ret)
+ pr_debug("failed to compute shared secred, err %d\n", ret);
+ else
+ pr_debug("%s: shared secret %*ph\n", __func__,
+ (int)req->sq->dhchap_skey_len,
+ req->sq->dhchap_skey);
+
+ return ret;
+}
diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index d1f749ecbe4a..0414ff7f4873 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -1743,10 +1743,41 @@ static ssize_t nvmet_host_dhchap_hash_store(struct config_item *item,
CONFIGFS_ATTR(nvmet_host_, dhchap_hash);
+static ssize_t nvmet_host_dhchap_dhgroup_show(struct config_item *item,
+ char *page)
+{
+ struct nvmet_host *host = to_host(item);
+ const char *dhgroup = nvme_auth_dhgroup_name(host->dhchap_dhgroup_id);
+
+ return sprintf(page, "%s\n", dhgroup ? dhgroup : "none");
+}
+
+static ssize_t nvmet_host_dhchap_dhgroup_store(struct config_item *item,
+ const char *page, size_t count)
+{
+ struct nvmet_host *host = to_host(item);
+ int dhgroup_id;
+
+ dhgroup_id = nvme_auth_dhgroup_id(page);
+ if (dhgroup_id < 0)
+ return -EINVAL;
+ if (dhgroup_id != NVME_AUTH_DHCHAP_DHGROUP_NULL) {
+ const char *kpp = nvme_auth_dhgroup_kpp(dhgroup_id);
+
+ if (!crypto_has_kpp(kpp, 0, 0))
+ return -EINVAL;
+ }
+ host->dhchap_dhgroup_id = dhgroup_id;
+ return count;
+}
+
+CONFIGFS_ATTR(nvmet_host_, dhchap_dhgroup);
+
static struct configfs_attribute *nvmet_host_attrs[] = {
&nvmet_host_attr_dhchap_key,
&nvmet_host_attr_dhchap_ctrl_key,
&nvmet_host_attr_dhchap_hash,
+ &nvmet_host_attr_dhchap_dhgroup,
NULL,
};
#endif /* CONFIG_NVME_TARGET_AUTH */
diff --git a/drivers/nvme/target/fabrics-cmd-auth.c b/drivers/nvme/target/fabrics-cmd-auth.c
index 10ab646e85e5..a11de590a5a4 100644
--- a/drivers/nvme/target/fabrics-cmd-auth.c
+++ b/drivers/nvme/target/fabrics-cmd-auth.c
@@ -64,13 +64,24 @@ static u16 nvmet_auth_negotiate(struct nvmet_req *req, void *d)
null_dh = dhgid;
continue;
}
+ if (ctrl->dh_tfm && ctrl->dh_gid == dhgid) {
+ pr_debug("%s: ctrl %d qid %d: reusing existing DH group %d\n",
+ __func__, ctrl->cntlid, req->sq->qid, dhgid);
+ break;
+ }
+ if (nvmet_setup_dhgroup(ctrl, dhgid) < 0)
+ continue;
+ if (nvme_auth_gen_privkey(ctrl->dh_tfm, dhgid) == 0)
+ break;
+ crypto_free_kpp(ctrl->dh_tfm);
+ ctrl->dh_tfm = NULL;
+ ctrl->dh_gid = 0;
}
- if (null_dh < 0) {
+ if (!ctrl->dh_tfm && null_dh < 0) {
pr_debug("%s: ctrl %d qid %d: no DH group selected\n",
__func__, ctrl->cntlid, req->sq->qid);
return NVME_AUTH_DHCHAP_FAILURE_DHGROUP_UNUSABLE;
}
- ctrl->dh_gid = null_dh;
pr_debug("%s: ctrl %d qid %d: DH group %s (%d)\n",
__func__, ctrl->cntlid, req->sq->qid,
nvme_auth_dhgroup_name(ctrl->dh_gid), ctrl->dh_gid);
@@ -92,7 +103,11 @@ static u16 nvmet_auth_reply(struct nvmet_req *req, void *d)
return NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
if (dhvlen) {
- return NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
+ if (!ctrl->dh_tfm)
+ return NVME_AUTH_DHCHAP_FAILURE_INCORRECT_PAYLOAD;
+ if (nvmet_auth_ctrl_sesskey(req, data->rval + 2 * data->hl,
+ dhvlen) < 0)
+ return NVME_AUTH_DHCHAP_FAILURE_DHGROUP_UNUSABLE;
}
response = kmalloc(data->hl, GFP_KERNEL);
@@ -305,6 +320,8 @@ static int nvmet_auth_challenge(struct nvmet_req *req, void *d, int al)
int hash_len = crypto_shash_digestsize(ctrl->shash_tfm);
int data_size = sizeof(*d) + hash_len;
+ if (ctrl->dh_tfm)
+ data_size += ctrl->dh_keysize;
if (al < data_size) {
pr_debug("%s: buffer too small (al %d need %d)\n", __func__,
al, data_size);
@@ -323,9 +340,15 @@ static int nvmet_auth_challenge(struct nvmet_req *req, void *d, int al)
return -ENOMEM;
get_random_bytes(req->sq->dhchap_c1, data->hl);
memcpy(data->cval, req->sq->dhchap_c1, data->hl);
+ if (ctrl->dh_tfm) {
+ data->dhgid = ctrl->dh_gid;
+ data->dhvlen = cpu_to_le32(ctrl->dh_keysize);
+ ret = nvmet_auth_ctrl_exponential(req, data->cval + data->hl,
+ ctrl->dh_keysize);
+ }
pr_debug("%s: ctrl %d qid %d seq %d transaction %d hl %d dhvlen %d\n",
__func__, ctrl->cntlid, req->sq->qid, req->sq->dhchap_s1,
- req->sq->dhchap_tid, data->hl, 0);
+ req->sq->dhchap_tid, data->hl, ctrl->dh_keysize);
return ret;
}
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 7fdd48193f83..4e34ee0e51ec 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -229,6 +229,7 @@ struct nvmet_ctrl {
size_t dhchap_ctrl_key_len;
struct crypto_shash *shash_tfm;
u8 shash_id;
+ struct crypto_kpp *dh_tfm;
u32 dh_gid;
u32 dh_keysize;
#endif
@@ -698,6 +699,7 @@ int nvmet_setup_auth(struct nvmet_ctrl *ctrl);
void nvmet_init_auth(struct nvmet_ctrl *ctrl, struct nvmet_req *req);
void nvmet_destroy_auth(struct nvmet_ctrl *ctrl);
void nvmet_auth_sq_free(struct nvmet_sq *sq);
+int nvmet_setup_dhgroup(struct nvmet_ctrl *ctrl, int dhgroup_id);
bool nvmet_check_auth_status(struct nvmet_req *req);
int nvmet_auth_host_hash(struct nvmet_req *req, u8 *response,
unsigned int hash_len);
@@ -707,6 +709,10 @@ static inline bool nvmet_has_auth(struct nvmet_ctrl *ctrl)
{
return ctrl->shash_tfm != NULL;
}
+int nvmet_auth_ctrl_exponential(struct nvmet_req *req,
+ u8 *buf, int buf_size);
+int nvmet_auth_ctrl_sesskey(struct nvmet_req *req,
+ u8 *buf, int buf_size);
#else
static inline int nvmet_setup_auth(struct nvmet_ctrl *ctrl)
{
--
2.29.2
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