Re: [PATCH] libceph: Use HMAC-SHA256 library instead of crypto_shash

[Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>]

On Thu, 2025-07-31 at 12:02 -0700, Eric Biggers wrote:
> Use the HMAC-SHA256 library functions instead of crypto_shash.  This is
> simpler and faster.
> 

Looks good and much cleaner.

Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>

Thanks,
Slava.

> Signed-off-by: Eric Biggers <ebiggers@kernel.org>
> ---
>  include/linux/ceph/messenger.h |  4 +-
>  net/ceph/Kconfig               |  3 +-
>  net/ceph/messenger_v2.c        | 77 ++++++++++------------------------
>  3 files changed, 26 insertions(+), 58 deletions(-)
> 
> diff --git a/include/linux/ceph/messenger.h b/include/linux/ceph/messenger.h
> index 1717cc57cdacd..4b49592a738fc 100644
> --- a/include/linux/ceph/messenger.h
> +++ b/include/linux/ceph/messenger.h
> @@ -1,9 +1,10 @@
>  /* SPDX-License-Identifier: GPL-2.0 */
>  #ifndef __FS_CEPH_MESSENGER_H
>  #define __FS_CEPH_MESSENGER_H
>  
> +#include <crypto/sha2.h>
>  #include <linux/bvec.h>
>  #include <linux/crypto.h>
>  #include <linux/kref.h>
>  #include <linux/mutex.h>
>  #include <linux/net.h>
> @@ -410,11 +411,12 @@ struct ceph_connection_v2_info {
>  
>  	struct ceph_frame_desc in_desc;
>  	struct ceph_msg_data_cursor in_cursor;
>  	struct ceph_msg_data_cursor out_cursor;
>  
> -	struct crypto_shash *hmac_tfm;  /* post-auth signature */
> +	struct hmac_sha256_key hmac_key;  /* post-auth signature */
> +	bool hmac_key_set;
>  	struct crypto_aead *gcm_tfm;  /* on-wire encryption */
>  	struct aead_request *gcm_req;
>  	struct crypto_wait gcm_wait;
>  	struct ceph_gcm_nonce in_gcm_nonce;
>  	struct ceph_gcm_nonce out_gcm_nonce;
> diff --git a/net/ceph/Kconfig b/net/ceph/Kconfig
> index 0aa21fcbf6ece..ea60e3ef08343 100644
> --- a/net/ceph/Kconfig
> +++ b/net/ceph/Kconfig
> @@ -4,12 +4,11 @@ config CEPH_LIB
>  	depends on INET
>  	select CRC32
>  	select CRYPTO_AES
>  	select CRYPTO_CBC
>  	select CRYPTO_GCM
> -	select CRYPTO_HMAC
> -	select CRYPTO_SHA256
> +	select CRYPTO_LIB_SHA256
>  	select CRYPTO
>  	select KEYS
>  	default n
>  	help
>  	  Choose Y or M here to include cephlib, which provides the
> diff --git a/net/ceph/messenger_v2.c b/net/ceph/messenger_v2.c
> index 5483b4eed94e1..c54c8b5a65261 100644
> --- a/net/ceph/messenger_v2.c
> +++ b/net/ceph/messenger_v2.c
> @@ -707,11 +707,11 @@ static int setup_crypto(struct ceph_connection *con,
>  	unsigned int noio_flag;
>  	int ret;
>  
>  	dout("%s con %p con_mode %d session_key_len %d con_secret_len %d\n",
>  	     __func__, con, con->v2.con_mode, session_key_len, con_secret_len);
> -	WARN_ON(con->v2.hmac_tfm || con->v2.gcm_tfm || con->v2.gcm_req);
> +	WARN_ON(con->v2.hmac_key_set || con->v2.gcm_tfm || con->v2.gcm_req);
>  
>  	if (con->v2.con_mode != CEPH_CON_MODE_CRC &&
>  	    con->v2.con_mode != CEPH_CON_MODE_SECURE) {
>  		pr_err("bad con_mode %d\n", con->v2.con_mode);
>  		return -EINVAL;
> @@ -721,26 +721,12 @@ static int setup_crypto(struct ceph_connection *con,
>  		WARN_ON(con->v2.con_mode != CEPH_CON_MODE_CRC);
>  		WARN_ON(con_secret_len);
>  		return 0;  /* auth_none */
>  	}
>  
> -	noio_flag = memalloc_noio_save();
> -	con->v2.hmac_tfm = crypto_alloc_shash("hmac(sha256)", 0, 0);
> -	memalloc_noio_restore(noio_flag);
> -	if (IS_ERR(con->v2.hmac_tfm)) {
> -		ret = PTR_ERR(con->v2.hmac_tfm);
> -		con->v2.hmac_tfm = NULL;
> -		pr_err("failed to allocate hmac tfm context: %d\n", ret);
> -		return ret;
> -	}
> -
> -	ret = crypto_shash_setkey(con->v2.hmac_tfm, session_key,
> -				  session_key_len);
> -	if (ret) {
> -		pr_err("failed to set hmac key: %d\n", ret);
> -		return ret;
> -	}
> +	hmac_sha256_preparekey(&con->v2.hmac_key, session_key, session_key_len);
> +	con->v2.hmac_key_set = true;
>  
>  	if (con->v2.con_mode == CEPH_CON_MODE_CRC) {
>  		WARN_ON(con_secret_len);
>  		return 0;  /* auth_x, plain mode */
>  	}
> @@ -791,42 +777,30 @@ static int setup_crypto(struct ceph_connection *con,
>  	       con_secret + CEPH_GCM_KEY_LEN + CEPH_GCM_IV_LEN,
>  	       CEPH_GCM_IV_LEN);
>  	return 0;  /* auth_x, secure mode */
>  }
>  
> -static int ceph_hmac_sha256(struct ceph_connection *con,
> -			    const struct kvec *kvecs, int kvec_cnt, u8 *hmac)
> +static void ceph_hmac_sha256(struct ceph_connection *con,
> +			     const struct kvec *kvecs, int kvec_cnt,
> +			     u8 hmac[SHA256_DIGEST_SIZE])
>  {
> -	SHASH_DESC_ON_STACK(desc, con->v2.hmac_tfm);  /* tfm arg is ignored */
> -	int ret;
> +	struct hmac_sha256_ctx ctx;
>  	int i;
>  
> -	dout("%s con %p hmac_tfm %p kvec_cnt %d\n", __func__, con,
> -	     con->v2.hmac_tfm, kvec_cnt);
> +	dout("%s con %p hmac_key_set %d kvec_cnt %d\n", __func__, con,
> +	     con->v2.hmac_key_set, kvec_cnt);
>  
> -	if (!con->v2.hmac_tfm) {
> +	if (!con->v2.hmac_key_set) {
>  		memset(hmac, 0, SHA256_DIGEST_SIZE);
> -		return 0;  /* auth_none */
> +		return;  /* auth_none */
>  	}
>  
> -	desc->tfm = con->v2.hmac_tfm;
> -	ret = crypto_shash_init(desc);
> -	if (ret)
> -		goto out;
> -
> -	for (i = 0; i < kvec_cnt; i++) {
> -		ret = crypto_shash_update(desc, kvecs[i].iov_base,
> -					  kvecs[i].iov_len);
> -		if (ret)
> -			goto out;
> -	}
> -
> -	ret = crypto_shash_final(desc, hmac);
> -
> -out:
> -	shash_desc_zero(desc);
> -	return ret;  /* auth_x, both plain and secure modes */
> +	/* auth_x, both plain and secure modes */
> +	hmac_sha256_init(&ctx, &con->v2.hmac_key);
> +	for (i = 0; i < kvec_cnt; i++)
> +		hmac_sha256_update(&ctx, kvecs[i].iov_base, kvecs[i].iov_len);
> +	hmac_sha256_final(&ctx, hmac);
>  }
>  
>  static void gcm_inc_nonce(struct ceph_gcm_nonce *nonce)
>  {
>  	u64 counter;
> @@ -1453,21 +1427,18 @@ static int prepare_auth_request_more(struct ceph_connection *con,
>  }
>  
>  static int prepare_auth_signature(struct ceph_connection *con)
>  {
>  	void *buf;
> -	int ret;
>  
>  	buf = alloc_conn_buf(con, head_onwire_len(SHA256_DIGEST_SIZE,
>  						  con_secure(con)));
>  	if (!buf)
>  		return -ENOMEM;
>  
> -	ret = ceph_hmac_sha256(con, con->v2.in_sign_kvecs,
> -			       con->v2.in_sign_kvec_cnt, CTRL_BODY(buf));
> -	if (ret)
> -		return ret;
> +	ceph_hmac_sha256(con, con->v2.in_sign_kvecs, con->v2.in_sign_kvec_cnt,
> +			 CTRL_BODY(buf));
>  
>  	return prepare_control(con, FRAME_TAG_AUTH_SIGNATURE, buf,
>  			       SHA256_DIGEST_SIZE);
>  }
>  
> @@ -2458,14 +2429,12 @@ static int process_auth_signature(struct ceph_connection *con,
>  	if (con->state != CEPH_CON_S_V2_AUTH_SIGNATURE) {
>  		con->error_msg = "protocol error, unexpected auth_signature";
>  		return -EINVAL;
>  	}
>  
> -	ret = ceph_hmac_sha256(con, con->v2.out_sign_kvecs,
> -			       con->v2.out_sign_kvec_cnt, hmac);
> -	if (ret)
> -		return ret;
> +	ceph_hmac_sha256(con, con->v2.out_sign_kvecs, con->v2.out_sign_kvec_cnt,
> +			 hmac);
>  
>  	ceph_decode_need(&p, end, SHA256_DIGEST_SIZE, bad);
>  	if (crypto_memneq(p, hmac, SHA256_DIGEST_SIZE)) {
>  		con->error_msg = "integrity error, bad auth signature";
>  		return -EBADMSG;
> @@ -3812,14 +3781,12 @@ void ceph_con_v2_reset_protocol(struct ceph_connection *con)
>  
>  	con->v2.con_mode = CEPH_CON_MODE_UNKNOWN;
>  	memzero_explicit(&con->v2.in_gcm_nonce, CEPH_GCM_IV_LEN);
>  	memzero_explicit(&con->v2.out_gcm_nonce, CEPH_GCM_IV_LEN);
>  
> -	if (con->v2.hmac_tfm) {
> -		crypto_free_shash(con->v2.hmac_tfm);
> -		con->v2.hmac_tfm = NULL;
> -	}
> +	memzero_explicit(&con->v2.hmac_key, sizeof(con->v2.hmac_key));
> +	con->v2.hmac_key_set = false;
>  	if (con->v2.gcm_req) {
>  		aead_request_free(con->v2.gcm_req);
>  		con->v2.gcm_req = NULL;
>  	}
>  	if (con->v2.gcm_tfm) {
> 
> base-commit: d6084bb815c453de27af8071a23163a711586a6c