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>

diff --git a/drivers/nvme/common/auth.c b/drivers/nvme/common/auth.c
index adb43d3..94cc7ca 100644 (file)
--- a/drivers/nvme/common/auth.c
+++ b/drivers/nvme/common/auth.c
@@ -295,6 +295,159 @@ out_free_key:
 }
 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;

diff --git a/drivers/nvme/host/Kconfig b/drivers/nvme/host/Kconfig
index 6c503f4..2f6a7f8 100644 (file)
--- a/drivers/nvme/host/Kconfig
+++ b/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.
 

diff --git a/drivers/nvme/host/auth.c b/drivers/nvme/host/auth.c
index 9766bff..c8a6db7 100644 (file)
--- a/drivers/nvme/host/auth.c
+++ b/drivers/nvme/host/auth.c
@@ -18,6 +18,7 @@ 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;
@@ -33,6 +34,12 @@ 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;
 };
 
 #define nvme_auth_flags_from_qid(qid) \
@@ -137,6 +144,7 @@ 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) {
@@ -207,15 +215,54 @@ select_kpp:
                         "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",
@@ -225,8 +272,21 @@ select_kpp:
        }
        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;
 }
@@ -239,6 +299,9 @@ 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;
@@ -249,7 +312,7 @@ 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->ctrl_key) {
                get_random_bytes(chap->c2, chap->hash_len);
@@ -264,6 +327,14 @@ 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;
 }
 
@@ -381,6 +452,21 @@ 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)
@@ -443,6 +529,20 @@ 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",
@@ -492,8 +592,81 @@ out:
        return ret;
 }
 
+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;
@@ -508,6 +681,11 @@ 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);
@@ -566,6 +744,17 @@ 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) {
+                       chap->error = 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/include/linux/nvme-auth.h b/include/linux/nvme-auth.h
index 3544568..dcb8030 100644 (file)
--- a/include/linux/nvme-auth.h
+++ b/include/linux/nvme-auth.h
@@ -29,5 +29,13 @@ struct nvme_dhchap_key *nvme_auth_extract_key(unsigned char *secret,
 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_generate_key(u8 *secret, struct nvme_dhchap_key **ret_key);
+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 */