Commit 1cab50da authored by Chris Leech's avatar Chris Leech Committed by Keith Busch
Browse files

nvme-auth: add hkdf_expand_label() 



Provide an implementation of RFC 8446 (TLS 1.3) HKDF-Expand-Label

Signed-off-by: default avatarChris Leech <cleech@redhat.com>
Signed-off-by: default avatarHannes Reinecke <hare@kernel.org>
Signed-off-by: default avatarKeith Busch <kbusch@kernel.org>
parent df4666a4

drivers/nvme/common/auth.c

+53 −0
Original line number Diff line number Diff line
@@ -683,6 +683,59 @@ int nvme_auth_generate_digest(u8 hmac_id, u8 *psk, size_t psk_len, 
}

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