1 files changed, 337 insertions, 0 deletions
diff --git a/drivers/nvme/common/auth.c b/drivers/nvme/common/auth.c
index 9b7126e1a19d..2c092ec8c0a9 100644
--- a/drivers/nvme/common/auth.c
+++ b/drivers/nvme/common/auth.c
@@ -11,9 +11,12 @@
 #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);
 
@@ -471,5 +474,339 @@ int nvme_auth_generate_key(u8 *secret, struct nvme_dhchap_key **ret_key)
 }
 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 too 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);
+	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);
+
+/**
+ * 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 *psk_prefix = "tls13 nvme-tls-psk";
+	static const char default_salt[HKDF_MAX_HASHLEN];
+	size_t info_len, prk_len;
+	char *info;
+	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;
+
+	/*
+	 * 2 addtional bytes for the length field from HDKF-Expand-Label,
+	 * 2 addtional bytes for the HMAC ID, and one byte for the space
+	 * separator.
+	 */
+	info_len = strlen(psk_digest) + strlen(psk_prefix) + 5;
+	info = kzalloc(info_len + 1, GFP_KERNEL);
+	if (!info) {
+		ret = -ENOMEM;
+		goto out_free_prk;
+	}
+
+	put_unaligned_be16(psk_len, info);
+	memcpy(info + 2, psk_prefix, strlen(psk_prefix));
+	sprintf(info + 2 + strlen(psk_prefix), "%02d %s", hmac_id, psk_digest);
+
+	tls_key = kzalloc(psk_len, GFP_KERNEL);
+	if (!tls_key) {
+		ret = -ENOMEM;
+		goto out_free_info;
+	}
+	ret = hkdf_expand(hmac_tfm, info, info_len, tls_key, psk_len);
+	if (ret) {
+		kfree(tls_key);
+		goto out_free_info;
+	}
+	*ret_psk = tls_key;
+
+out_free_info:
+	kfree(info);
+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");