diff options
Diffstat (limited to 'drivers/nvme/common/auth.c')
| -rw-r--r-- | drivers/nvme/common/auth.c | 847 |
1 files changed, 847 insertions, 0 deletions
diff --git a/drivers/nvme/common/auth.c b/drivers/nvme/common/auth.c new file mode 100644 index 000000000000..e07e7d4bf8b6 --- /dev/null +++ b/drivers/nvme/common/auth.c @@ -0,0 +1,847 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2020 Hannes Reinecke, SUSE Linux + */ + +#include <linux/module.h> +#include <linux/crc32.h> +#include <linux/base64.h> +#include <linux/prandom.h> +#include <linux/scatterlist.h> +#include <linux/unaligned.h> +#include <crypto/hash.h> +#include <crypto/dh.h> +#include <crypto/hkdf.h> +#include <linux/nvme.h> +#include <linux/nvme-auth.h> + +#define HKDF_MAX_HASHLEN 64 + +static u32 nvme_dhchap_seqnum; +static DEFINE_MUTEX(nvme_dhchap_mutex); + +u32 nvme_auth_get_seqnum(void) +{ + u32 seqnum; + + mutex_lock(&nvme_dhchap_mutex); + if (!nvme_dhchap_seqnum) + nvme_dhchap_seqnum = get_random_u32(); + else { + nvme_dhchap_seqnum++; + if (!nvme_dhchap_seqnum) + nvme_dhchap_seqnum++; + } + seqnum = nvme_dhchap_seqnum; + mutex_unlock(&nvme_dhchap_mutex); + return seqnum; +} +EXPORT_SYMBOL_GPL(nvme_auth_get_seqnum); + +static struct nvme_auth_dhgroup_map { + const char name[16]; + const char kpp[16]; +} dhgroup_map[] = { + [NVME_AUTH_DHGROUP_NULL] = { + .name = "null", .kpp = "null" }, + [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)" }, +}; + +const char *nvme_auth_dhgroup_name(u8 dhgroup_id) +{ + if (dhgroup_id >= ARRAY_SIZE(dhgroup_map)) + return NULL; + return dhgroup_map[dhgroup_id].name; +} +EXPORT_SYMBOL_GPL(nvme_auth_dhgroup_name); + +const char *nvme_auth_dhgroup_kpp(u8 dhgroup_id) +{ + if (dhgroup_id >= ARRAY_SIZE(dhgroup_map)) + return NULL; + return dhgroup_map[dhgroup_id].kpp; +} +EXPORT_SYMBOL_GPL(nvme_auth_dhgroup_kpp); + +u8 nvme_auth_dhgroup_id(const char *dhgroup_name) +{ + int i; + + if (!dhgroup_name || !strlen(dhgroup_name)) + return NVME_AUTH_DHGROUP_INVALID; + for (i = 0; i < ARRAY_SIZE(dhgroup_map); i++) { + if (!strlen(dhgroup_map[i].name)) + continue; + if (!strncmp(dhgroup_map[i].name, dhgroup_name, + strlen(dhgroup_map[i].name))) + return i; + } + return NVME_AUTH_DHGROUP_INVALID; +} +EXPORT_SYMBOL_GPL(nvme_auth_dhgroup_id); + +static struct nvme_dhchap_hash_map { + int len; + const char hmac[15]; + const char digest[8]; +} hash_map[] = { + [NVME_AUTH_HASH_SHA256] = { + .len = 32, + .hmac = "hmac(sha256)", + .digest = "sha256", + }, + [NVME_AUTH_HASH_SHA384] = { + .len = 48, + .hmac = "hmac(sha384)", + .digest = "sha384", + }, + [NVME_AUTH_HASH_SHA512] = { + .len = 64, + .hmac = "hmac(sha512)", + .digest = "sha512", + }, +}; + +const char *nvme_auth_hmac_name(u8 hmac_id) +{ + if (hmac_id >= ARRAY_SIZE(hash_map)) + return NULL; + return hash_map[hmac_id].hmac; +} +EXPORT_SYMBOL_GPL(nvme_auth_hmac_name); + +const char *nvme_auth_digest_name(u8 hmac_id) +{ + if (hmac_id >= ARRAY_SIZE(hash_map)) + return NULL; + return hash_map[hmac_id].digest; +} +EXPORT_SYMBOL_GPL(nvme_auth_digest_name); + +u8 nvme_auth_hmac_id(const char *hmac_name) +{ + int i; + + if (!hmac_name || !strlen(hmac_name)) + return NVME_AUTH_HASH_INVALID; + + for (i = 0; i < ARRAY_SIZE(hash_map); i++) { + if (!strlen(hash_map[i].hmac)) + continue; + if (!strncmp(hash_map[i].hmac, hmac_name, + strlen(hash_map[i].hmac))) + return i; + } + return NVME_AUTH_HASH_INVALID; +} +EXPORT_SYMBOL_GPL(nvme_auth_hmac_id); + +size_t nvme_auth_hmac_hash_len(u8 hmac_id) +{ + if (hmac_id >= ARRAY_SIZE(hash_map)) + return 0; + return hash_map[hmac_id].len; +} +EXPORT_SYMBOL_GPL(nvme_auth_hmac_hash_len); + +u32 nvme_auth_key_struct_size(u32 key_len) +{ + struct nvme_dhchap_key key; + + return struct_size(&key, key, key_len); +} +EXPORT_SYMBOL_GPL(nvme_auth_key_struct_size); + +struct nvme_dhchap_key *nvme_auth_extract_key(unsigned char *secret, + u8 key_hash) +{ + struct nvme_dhchap_key *key; + unsigned char *p; + u32 crc; + int ret, key_len; + size_t allocated_len = strlen(secret); + + /* Secret might be affixed with a ':' */ + p = strrchr(secret, ':'); + if (p) + allocated_len = p - secret; + key = nvme_auth_alloc_key(allocated_len, 0); + if (!key) + return ERR_PTR(-ENOMEM); + + key_len = base64_decode(secret, allocated_len, key->key, true, BASE64_STD); + if (key_len < 0) { + pr_debug("base64 key decoding error %d\n", + key_len); + ret = key_len; + goto out_free_secret; + } + + if (key_len != 36 && key_len != 52 && + key_len != 68) { + pr_err("Invalid key len %d\n", key_len); + ret = -EINVAL; + goto out_free_secret; + } + + /* The last four bytes is the CRC in little-endian format */ + key_len -= 4; + /* + * The linux implementation doesn't do pre- and post-increments, + * so we have to do it manually. + */ + crc = ~crc32(~0, key->key, key_len); + + if (get_unaligned_le32(key->key + key_len) != crc) { + pr_err("key crc mismatch (key %08x, crc %08x)\n", + get_unaligned_le32(key->key + key_len), crc); + ret = -EKEYREJECTED; + goto out_free_secret; + } + key->len = key_len; + key->hash = key_hash; + return key; +out_free_secret: + nvme_auth_free_key(key); + return ERR_PTR(ret); +} +EXPORT_SYMBOL_GPL(nvme_auth_extract_key); + +struct nvme_dhchap_key *nvme_auth_alloc_key(u32 len, u8 hash) +{ + u32 num_bytes = nvme_auth_key_struct_size(len); + struct nvme_dhchap_key *key = kzalloc(num_bytes, GFP_KERNEL); + + if (key) { + key->len = len; + key->hash = hash; + } + return key; +} +EXPORT_SYMBOL_GPL(nvme_auth_alloc_key); + +void nvme_auth_free_key(struct nvme_dhchap_key *key) +{ + if (!key) + return; + kfree_sensitive(key); +} +EXPORT_SYMBOL_GPL(nvme_auth_free_key); + +struct nvme_dhchap_key *nvme_auth_transform_key( + struct nvme_dhchap_key *key, char *nqn) +{ + const char *hmac_name; + struct crypto_shash *key_tfm; + SHASH_DESC_ON_STACK(shash, key_tfm); + struct nvme_dhchap_key *transformed_key; + int ret, key_len; + + if (!key) { + pr_warn("No key specified\n"); + return ERR_PTR(-ENOKEY); + } + if (key->hash == 0) { + key_len = nvme_auth_key_struct_size(key->len); + transformed_key = kmemdup(key, key_len, GFP_KERNEL); + if (!transformed_key) + return ERR_PTR(-ENOMEM); + return transformed_key; + } + hmac_name = nvme_auth_hmac_name(key->hash); + if (!hmac_name) { + pr_warn("Invalid key hash id %d\n", key->hash); + return ERR_PTR(-EINVAL); + } + + key_tfm = crypto_alloc_shash(hmac_name, 0, 0); + if (IS_ERR(key_tfm)) + return ERR_CAST(key_tfm); + + key_len = crypto_shash_digestsize(key_tfm); + transformed_key = nvme_auth_alloc_key(key_len, key->hash); + if (!transformed_key) { + ret = -ENOMEM; + goto out_free_key; + } + + shash->tfm = key_tfm; + ret = crypto_shash_setkey(key_tfm, key->key, key->len); + if (ret < 0) + goto out_free_transformed_key; + ret = crypto_shash_init(shash); + if (ret < 0) + goto out_free_transformed_key; + ret = crypto_shash_update(shash, nqn, strlen(nqn)); + if (ret < 0) + goto out_free_transformed_key; + ret = crypto_shash_update(shash, "NVMe-over-Fabrics", 17); + if (ret < 0) + goto out_free_transformed_key; + ret = crypto_shash_final(shash, transformed_key->key); + if (ret < 0) + goto out_free_transformed_key; + + crypto_free_shash(key_tfm); + + return transformed_key; + +out_free_transformed_key: + nvme_auth_free_key(transformed_key); +out_free_key: + crypto_free_shash(key_tfm); + + return ERR_PTR(ret); +} +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; + 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 algorithm %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; + } + + ret = crypto_shash_setkey(tfm, hashed_key, hlen); + if (ret) + goto out_free_hash; + + ret = crypto_shash_tfm_digest(tfm, challenge, hlen, aug); +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; + u8 key_hash; + + if (!secret) { + *ret_key = NULL; + return 0; + } + + if (sscanf(secret, "DHHC-1:%hhd:%*s:", &key_hash) != 1) + return -EINVAL; + + /* Pass in the secret without the 'DHHC-1:XX:' prefix */ + key = nvme_auth_extract_key(secret + 10, key_hash); + if (IS_ERR(key)) { + *ret_key = NULL; + return PTR_ERR(key); + } + + *ret_key = key; + return 0; +} +EXPORT_SYMBOL_GPL(nvme_auth_generate_key); + +/** + * nvme_auth_generate_psk - Generate a PSK for TLS + * @hmac_id: Hash function identifier + * @skey: Session key + * @skey_len: Length of @skey + * @c1: Value of challenge C1 + * @c2: Value of challenge C2 + * @hash_len: Hash length of the hash algorithm + * @ret_psk: Pointer to the resulting generated PSK + * @ret_len: length of @ret_psk + * + * Generate a PSK for TLS as specified in NVMe base specification, section + * 8.13.5.9: Generated PSK for TLS + * + * The generated PSK for TLS shall be computed applying the HMAC function + * using the hash function H( ) selected by the HashID parameter in the + * DH-HMAC-CHAP_Challenge message with the session key KS as key to the + * concatenation of the two challenges C1 and C2 (i.e., generated + * PSK = HMAC(KS, C1 || C2)). + * + * Returns 0 on success with a valid generated PSK pointer in @ret_psk and + * the length of @ret_psk in @ret_len, or a negative error number otherwise. + */ +int nvme_auth_generate_psk(u8 hmac_id, u8 *skey, size_t skey_len, + u8 *c1, u8 *c2, size_t hash_len, u8 **ret_psk, size_t *ret_len) +{ + struct crypto_shash *tfm; + SHASH_DESC_ON_STACK(shash, tfm); + u8 *psk; + const char *hmac_name; + int ret, psk_len; + + if (!c1 || !c2) + return -EINVAL; + + hmac_name = nvme_auth_hmac_name(hmac_id); + if (!hmac_name) { + pr_warn("%s: invalid hash algorithm %d\n", + __func__, hmac_id); + return -EINVAL; + } + + tfm = crypto_alloc_shash(hmac_name, 0, 0); + if (IS_ERR(tfm)) + return PTR_ERR(tfm); + + psk_len = crypto_shash_digestsize(tfm); + psk = kzalloc(psk_len, GFP_KERNEL); + if (!psk) { + ret = -ENOMEM; + goto out_free_tfm; + } + + shash->tfm = tfm; + ret = crypto_shash_setkey(tfm, skey, skey_len); + if (ret) + goto out_free_psk; + + ret = crypto_shash_init(shash); + if (ret) + goto out_free_psk; + + ret = crypto_shash_update(shash, c1, hash_len); + if (ret) + goto out_free_psk; + + ret = crypto_shash_update(shash, c2, hash_len); + if (ret) + goto out_free_psk; + + ret = crypto_shash_final(shash, psk); + if (!ret) { + *ret_psk = psk; + *ret_len = psk_len; + } + +out_free_psk: + if (ret) + kfree_sensitive(psk); +out_free_tfm: + crypto_free_shash(tfm); + + return ret; +} +EXPORT_SYMBOL_GPL(nvme_auth_generate_psk); + +/** + * nvme_auth_generate_digest - Generate TLS PSK digest + * @hmac_id: Hash function identifier + * @psk: Generated input PSK + * @psk_len: Length of @psk + * @subsysnqn: NQN of the subsystem + * @hostnqn: NQN of the host + * @ret_digest: Pointer to the returned digest + * + * Generate a TLS PSK digest as specified in TP8018 Section 3.6.1.3: + * TLS PSK and PSK identity Derivation + * + * The PSK digest shall be computed by encoding in Base64 (refer to RFC + * 4648) the result of the application of the HMAC function using the hash + * function specified in item 4 above (ie the hash function of the cipher + * suite associated with the PSK identity) with the PSK as HMAC key to the + * concatenation of: + * - the NQN of the host (i.e., NQNh) not including the null terminator; + * - a space character; + * - the NQN of the NVM subsystem (i.e., NQNc) not including the null + * terminator; + * - a space character; and + * - the seventeen ASCII characters "NVMe-over-Fabrics" + * (i.e., <PSK digest> = Base64(HMAC(PSK, NQNh || " " || NQNc || " " || + * "NVMe-over-Fabrics"))). + * The length of the PSK digest depends on the hash function used to compute + * it as follows: + * - If the SHA-256 hash function is used, the resulting PSK digest is 44 + * characters long; or + * - If the SHA-384 hash function is used, the resulting PSK digest is 64 + * characters long. + * + * Returns 0 on success with a valid digest pointer in @ret_digest, or a + * negative error number on failure. + */ +int nvme_auth_generate_digest(u8 hmac_id, u8 *psk, size_t psk_len, + char *subsysnqn, char *hostnqn, u8 **ret_digest) +{ + struct crypto_shash *tfm; + SHASH_DESC_ON_STACK(shash, tfm); + u8 *digest, *enc; + const char *hmac_name; + size_t digest_len, hmac_len; + int ret; + + if (WARN_ON(!subsysnqn || !hostnqn)) + return -EINVAL; + + hmac_name = nvme_auth_hmac_name(hmac_id); + if (!hmac_name) { + pr_warn("%s: invalid hash algorithm %d\n", + __func__, hmac_id); + return -EINVAL; + } + + switch (nvme_auth_hmac_hash_len(hmac_id)) { + case 32: + hmac_len = 44; + break; + case 48: + hmac_len = 64; + break; + default: + pr_warn("%s: invalid hash algorithm '%s'\n", + __func__, hmac_name); + return -EINVAL; + } + + enc = kzalloc(hmac_len + 1, GFP_KERNEL); + if (!enc) + return -ENOMEM; + + tfm = crypto_alloc_shash(hmac_name, 0, 0); + if (IS_ERR(tfm)) { + ret = PTR_ERR(tfm); + goto out_free_enc; + } + + digest_len = crypto_shash_digestsize(tfm); + digest = kzalloc(digest_len, GFP_KERNEL); + if (!digest) { + ret = -ENOMEM; + goto out_free_tfm; + } + + shash->tfm = tfm; + ret = crypto_shash_setkey(tfm, psk, psk_len); + if (ret) + goto out_free_digest; + + ret = crypto_shash_init(shash); + if (ret) + goto out_free_digest; + + ret = crypto_shash_update(shash, hostnqn, strlen(hostnqn)); + if (ret) + goto out_free_digest; + + ret = crypto_shash_update(shash, " ", 1); + if (ret) + goto out_free_digest; + + ret = crypto_shash_update(shash, subsysnqn, strlen(subsysnqn)); + if (ret) + goto out_free_digest; + + ret = crypto_shash_update(shash, " NVMe-over-Fabrics", 18); + if (ret) + goto out_free_digest; + + ret = crypto_shash_final(shash, digest); + if (ret) + goto out_free_digest; + + ret = base64_encode(digest, digest_len, enc, true, BASE64_STD); + if (ret < hmac_len) { + ret = -ENOKEY; + goto out_free_digest; + } + *ret_digest = enc; + ret = 0; + +out_free_digest: + kfree_sensitive(digest); +out_free_tfm: + crypto_free_shash(tfm); +out_free_enc: + if (ret) + kfree_sensitive(enc); + + return ret; +} +EXPORT_SYMBOL_GPL(nvme_auth_generate_digest); + +/** + * hkdf_expand_label - HKDF-Expand-Label (RFC 8846 section 7.1) + * @hmac_tfm: hash context keyed with pseudorandom key + * @label: ASCII label without "tls13 " prefix + * @labellen: length of @label + * @context: context bytes + * @contextlen: length of @context + * @okm: output keying material + * @okmlen: length of @okm + * + * Build the TLS 1.3 HkdfLabel structure and invoke hkdf_expand(). + * + * Returns 0 on success with output keying material stored in @okm, + * or a negative errno value otherwise. + */ +static int hkdf_expand_label(struct crypto_shash *hmac_tfm, + const u8 *label, unsigned int labellen, + const u8 *context, unsigned int contextlen, + u8 *okm, unsigned int okmlen) +{ + int err; + u8 *info; + unsigned int infolen; + const char *tls13_prefix = "tls13 "; + unsigned int prefixlen = strlen(tls13_prefix); + + if (WARN_ON(labellen > (255 - prefixlen))) + return -EINVAL; + if (WARN_ON(contextlen > 255)) + return -EINVAL; + + infolen = 2 + (1 + prefixlen + labellen) + (1 + contextlen); + info = kzalloc(infolen, GFP_KERNEL); + if (!info) + return -ENOMEM; + + /* HkdfLabel.Length */ + put_unaligned_be16(okmlen, info); + + /* HkdfLabel.Label */ + info[2] = prefixlen + labellen; + memcpy(info + 3, tls13_prefix, prefixlen); + memcpy(info + 3 + prefixlen, label, labellen); + + /* HkdfLabel.Context */ + info[3 + prefixlen + labellen] = contextlen; + memcpy(info + 4 + prefixlen + labellen, context, contextlen); + + err = hkdf_expand(hmac_tfm, info, infolen, okm, okmlen); + kfree_sensitive(info); + return err; +} + +/** + * nvme_auth_derive_tls_psk - Derive TLS PSK + * @hmac_id: Hash function identifier + * @psk: generated input PSK + * @psk_len: size of @psk + * @psk_digest: TLS PSK digest + * @ret_psk: Pointer to the resulting TLS PSK + * + * Derive a TLS PSK as specified in TP8018 Section 3.6.1.3: + * TLS PSK and PSK identity Derivation + * + * The TLS PSK shall be derived as follows from an input PSK + * (i.e., either a retained PSK or a generated PSK) and a PSK + * identity using the HKDF-Extract and HKDF-Expand-Label operations + * (refer to RFC 5869 and RFC 8446) where the hash function is the + * one specified by the hash specifier of the PSK identity: + * 1. PRK = HKDF-Extract(0, Input PSK); and + * 2. TLS PSK = HKDF-Expand-Label(PRK, "nvme-tls-psk", PskIdentityContext, L), + * where PskIdentityContext is the hash identifier indicated in + * the PSK identity concatenated to a space character and to the + * Base64 PSK digest (i.e., "<hash> <PSK digest>") and L is the + * output size in bytes of the hash function (i.e., 32 for SHA-256 + * and 48 for SHA-384). + * + * Returns 0 on success with a valid psk pointer in @ret_psk or a negative + * error number otherwise. + */ +int nvme_auth_derive_tls_psk(int hmac_id, u8 *psk, size_t psk_len, + u8 *psk_digest, u8 **ret_psk) +{ + struct crypto_shash *hmac_tfm; + const char *hmac_name; + const char *label = "nvme-tls-psk"; + static const char default_salt[HKDF_MAX_HASHLEN]; + size_t prk_len; + const char *ctx; + unsigned char *prk, *tls_key; + int ret; + + hmac_name = nvme_auth_hmac_name(hmac_id); + if (!hmac_name) { + pr_warn("%s: invalid hash algorithm %d\n", + __func__, hmac_id); + return -EINVAL; + } + if (hmac_id == NVME_AUTH_HASH_SHA512) { + pr_warn("%s: unsupported hash algorithm %s\n", + __func__, hmac_name); + return -EINVAL; + } + + hmac_tfm = crypto_alloc_shash(hmac_name, 0, 0); + if (IS_ERR(hmac_tfm)) + return PTR_ERR(hmac_tfm); + + prk_len = crypto_shash_digestsize(hmac_tfm); + prk = kzalloc(prk_len, GFP_KERNEL); + if (!prk) { + ret = -ENOMEM; + goto out_free_shash; + } + + if (WARN_ON(prk_len > HKDF_MAX_HASHLEN)) { + ret = -EINVAL; + goto out_free_prk; + } + ret = hkdf_extract(hmac_tfm, psk, psk_len, + default_salt, prk_len, prk); + if (ret) + goto out_free_prk; + + ret = crypto_shash_setkey(hmac_tfm, prk, prk_len); + if (ret) + goto out_free_prk; + + ctx = kasprintf(GFP_KERNEL, "%02d %s", hmac_id, psk_digest); + if (!ctx) { + ret = -ENOMEM; + goto out_free_prk; + } + + tls_key = kzalloc(psk_len, GFP_KERNEL); + if (!tls_key) { + ret = -ENOMEM; + goto out_free_ctx; + } + ret = hkdf_expand_label(hmac_tfm, + label, strlen(label), + ctx, strlen(ctx), + tls_key, psk_len); + if (ret) { + kfree(tls_key); + goto out_free_ctx; + } + *ret_psk = tls_key; + +out_free_ctx: + kfree(ctx); +out_free_prk: + kfree(prk); +out_free_shash: + crypto_free_shash(hmac_tfm); + + return ret; +} +EXPORT_SYMBOL_GPL(nvme_auth_derive_tls_psk); + +MODULE_DESCRIPTION("NVMe Authentication framework"); +MODULE_LICENSE("GPL v2"); |