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Date: Tue, 25 Aug 2020 16:14:53 +0300
From: Tero Kristo <t-kristo@...com>
To: Herbert Xu <herbert@...dor.apana.org.au>,
kernel test robot <lkp@...el.com>
CC: Keerthy <j-keerthy@...com>, <kbuild-all@...ts.01.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] crypto: sa2ul - Reduce stack usage
On 24/08/2020 16:12, Herbert Xu wrote:
> On Sun, Aug 16, 2020 at 02:56:43PM +0800, kernel test robot wrote:
>>
>> drivers/crypto/sa2ul.c: In function 'sa_prepare_iopads':
>>>> drivers/crypto/sa2ul.c:432:1: warning: the frame size of 1076 bytes is larger than 1024 bytes [-Wframe-larger-than=]
>
> This patch tries to reduce the stack frame size in sa2ul.
>
> ---8<---
> This patch reduces the stack usage in sa2ul:
>
> 1. Move the exported sha state into sa_prepare_iopads so that it
> can occupy the same space as the k_pad buffer.
>
> 2. Use one buffer for ipad/opad in sa_prepare_iopads.
>
> 3. Remove ipad/opad buffer from sa_set_sc_auth.
>
> 4. Use async skcipher fallback and remove on-stack request from
> sa_cipher_run.
>
> Reported-by: kernel test robot <lkp@...el.com>
> Fixes: d2c8ac187fc9 ("crypto: sa2ul - Add AEAD algorithm support")
> Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
This patch seems ok, I also tested it locally so:
Reviewed-by: Tero Kristo <t-kristo@...com>
Tested-by: Tero Kristo <t-kristo@...com>
>
> diff --git a/drivers/crypto/sa2ul.c b/drivers/crypto/sa2ul.c
> index 5bc099052bd2..66629cad9531 100644
> --- a/drivers/crypto/sa2ul.c
> +++ b/drivers/crypto/sa2ul.c
> @@ -9,8 +9,10 @@
> * Tero Kristo
> */
> #include <linux/clk.h>
> +#include <linux/dma-mapping.h>
> #include <linux/dmaengine.h>
> #include <linux/dmapool.h>
> +#include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/of_device.h>
> #include <linux/platform_device.h>
> @@ -356,42 +358,45 @@ static void sa_swiz_128(u8 *in, u16 len)
> }
>
> /* Prepare the ipad and opad from key as per SHA algorithm step 1*/
> -static void prepare_kiopad(u8 *k_ipad, u8 *k_opad, const u8 *key, u16 key_sz)
> +static void prepare_kipad(u8 *k_ipad, const u8 *key, u16 key_sz)
> {
> int i;
>
> - for (i = 0; i < key_sz; i++) {
> + for (i = 0; i < key_sz; i++)
> k_ipad[i] = key[i] ^ 0x36;
> - k_opad[i] = key[i] ^ 0x5c;
> - }
>
> /* Instead of XOR with 0 */
> - for (; i < SHA1_BLOCK_SIZE; i++) {
> + for (; i < SHA1_BLOCK_SIZE; i++)
> k_ipad[i] = 0x36;
> +}
> +
> +static void prepare_kopad(u8 *k_opad, const u8 *key, u16 key_sz)
> +{
> + int i;
> +
> + for (i = 0; i < key_sz; i++)
> + k_opad[i] = key[i] ^ 0x5c;
> +
> + /* Instead of XOR with 0 */
> + for (; i < SHA1_BLOCK_SIZE; i++)
> k_opad[i] = 0x5c;
> - }
> }
>
> -static void sa_export_shash(struct shash_desc *hash, int block_size,
> +static void sa_export_shash(void *state, struct shash_desc *hash,
> int digest_size, __be32 *out)
> {
> - union {
> - struct sha1_state sha1;
> - struct sha256_state sha256;
> - struct sha512_state sha512;
> - } sha;
> - void *state;
> + struct sha1_state *sha1;
> + struct sha256_state *sha256;
> u32 *result;
> - int i;
>
> switch (digest_size) {
> case SHA1_DIGEST_SIZE:
> - state = &sha.sha1;
> - result = sha.sha1.state;
> + sha1 = state;
> + result = sha1->state;
> break;
> case SHA256_DIGEST_SIZE:
> - state = &sha.sha256;
> - result = sha.sha256.state;
> + sha256 = state;
> + result = sha256->state;
> break;
> default:
> dev_err(sa_k3_dev, "%s: bad digest_size=%d\n", __func__,
> @@ -401,8 +406,7 @@ static void sa_export_shash(struct shash_desc *hash, int block_size,
>
> crypto_shash_export(hash, state);
>
> - for (i = 0; i < digest_size >> 2; i++)
> - out[i] = cpu_to_be32(result[i]);
> + cpu_to_be32_array(out, result, digest_size / 4);
> }
>
> static void sa_prepare_iopads(struct algo_data *data, const u8 *key,
> @@ -411,24 +415,28 @@ static void sa_prepare_iopads(struct algo_data *data, const u8 *key,
> SHASH_DESC_ON_STACK(shash, data->ctx->shash);
> int block_size = crypto_shash_blocksize(data->ctx->shash);
> int digest_size = crypto_shash_digestsize(data->ctx->shash);
> - u8 k_ipad[SHA1_BLOCK_SIZE];
> - u8 k_opad[SHA1_BLOCK_SIZE];
> + union {
> + struct sha1_state sha1;
> + struct sha256_state sha256;
> + u8 k_pad[SHA1_BLOCK_SIZE];
> + } sha;
>
> shash->tfm = data->ctx->shash;
>
> - prepare_kiopad(k_ipad, k_opad, key, key_sz);
> -
> - memzero_explicit(ipad, block_size);
> - memzero_explicit(opad, block_size);
> + prepare_kipad(sha.k_pad, key, key_sz);
>
> crypto_shash_init(shash);
> - crypto_shash_update(shash, k_ipad, block_size);
> - sa_export_shash(shash, block_size, digest_size, ipad);
> + crypto_shash_update(shash, sha.k_pad, block_size);
> + sa_export_shash(&sha, shash, digest_size, ipad);
> +
> + prepare_kopad(sha.k_pad, key, key_sz);
>
> crypto_shash_init(shash);
> - crypto_shash_update(shash, k_opad, block_size);
> + crypto_shash_update(shash, sha.k_pad, block_size);
>
> - sa_export_shash(shash, block_size, digest_size, opad);
> + sa_export_shash(&sha, shash, digest_size, opad);
> +
> + memzero_explicit(&sha, sizeof(sha));
> }
>
> /* Derive the inverse key used in AES-CBC decryption operation */
> @@ -501,7 +509,8 @@ static int sa_set_sc_enc(struct algo_data *ad, const u8 *key, u16 key_sz,
> static void sa_set_sc_auth(struct algo_data *ad, const u8 *key, u16 key_sz,
> u8 *sc_buf)
> {
> - __be32 ipad[64], opad[64];
> + __be32 *ipad = (void *)(sc_buf + 32);
> + __be32 *opad = (void *)(sc_buf + 64);
>
> /* Set Authentication mode selector to hash processing */
> sc_buf[0] = SA_HASH_PROCESSING;
> @@ -510,14 +519,9 @@ static void sa_set_sc_auth(struct algo_data *ad, const u8 *key, u16 key_sz,
> sc_buf[1] |= ad->auth_ctrl;
>
> /* Copy the keys or ipad/opad */
> - if (ad->keyed_mac) {
> + if (ad->keyed_mac)
> ad->prep_iopad(ad, key, key_sz, ipad, opad);
> -
> - /* Copy ipad to AuthKey */
> - memcpy(&sc_buf[32], ipad, ad->hash_size);
> - /* Copy opad to Aux-1 */
> - memcpy(&sc_buf[64], opad, ad->hash_size);
> - } else {
> + else {
> /* basic hash */
> sc_buf[1] |= SA_BASIC_HASH;
> }
> @@ -814,7 +818,7 @@ static void sa_cipher_cra_exit(struct crypto_skcipher *tfm)
> sa_free_ctx_info(&ctx->enc, data);
> sa_free_ctx_info(&ctx->dec, data);
>
> - crypto_free_sync_skcipher(ctx->fallback.skcipher);
> + crypto_free_skcipher(ctx->fallback.skcipher);
> }
>
> static int sa_cipher_cra_init(struct crypto_skcipher *tfm)
> @@ -822,6 +826,7 @@ static int sa_cipher_cra_init(struct crypto_skcipher *tfm)
> struct sa_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
> struct sa_crypto_data *data = dev_get_drvdata(sa_k3_dev);
> const char *name = crypto_tfm_alg_name(&tfm->base);
> + struct crypto_skcipher *child;
> int ret;
>
> memzero_explicit(ctx, sizeof(*ctx));
> @@ -836,14 +841,17 @@ static int sa_cipher_cra_init(struct crypto_skcipher *tfm)
> return ret;
> }
>
> - ctx->fallback.skcipher =
> - crypto_alloc_sync_skcipher(name, 0, CRYPTO_ALG_NEED_FALLBACK);
> + child = crypto_alloc_skcipher(name, 0, CRYPTO_ALG_NEED_FALLBACK);
>
> - if (IS_ERR(ctx->fallback.skcipher)) {
> + if (IS_ERR(child)) {
> dev_err(sa_k3_dev, "Error allocating fallback algo %s\n", name);
> - return PTR_ERR(ctx->fallback.skcipher);
> + return PTR_ERR(child);
> }
>
> + ctx->fallback.skcipher = child;
> + crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) +
> + sizeof(struct skcipher_request));
> +
> dev_dbg(sa_k3_dev, "%s(0x%p) sc-ids(0x%x(0x%pad), 0x%x(0x%pad))\n",
> __func__, tfm, ctx->enc.sc_id, &ctx->enc.sc_phys,
> ctx->dec.sc_id, &ctx->dec.sc_phys);
> @@ -854,6 +862,7 @@ static int sa_cipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
> unsigned int keylen, struct algo_data *ad)
> {
> struct sa_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
> + struct crypto_skcipher *child = ctx->fallback.skcipher;
> int cmdl_len;
> struct sa_cmdl_cfg cfg;
> int ret;
> @@ -869,12 +878,10 @@ static int sa_cipher_setkey(struct crypto_skcipher *tfm, const u8 *key,
> cfg.enc_eng_id = ad->enc_eng.eng_id;
> cfg.iv_size = crypto_skcipher_ivsize(tfm);
>
> - crypto_sync_skcipher_clear_flags(ctx->fallback.skcipher,
> + crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
> + crypto_skcipher_set_flags(child, tfm->base.crt_flags &
> CRYPTO_TFM_REQ_MASK);
> - crypto_sync_skcipher_set_flags(ctx->fallback.skcipher,
> - tfm->base.crt_flags &
> - CRYPTO_TFM_REQ_MASK);
> - ret = crypto_sync_skcipher_setkey(ctx->fallback.skcipher, key, keylen);
> + ret = crypto_skcipher_setkey(child, key, keylen);
> if (ret)
> return ret;
>
> @@ -1234,7 +1241,6 @@ static int sa_cipher_run(struct skcipher_request *req, u8 *iv, int enc)
> crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
> struct crypto_alg *alg = req->base.tfm->__crt_alg;
> struct sa_req sa_req = { 0 };
> - int ret;
>
> if (!req->cryptlen)
> return 0;
> @@ -1246,20 +1252,18 @@ static int sa_cipher_run(struct skcipher_request *req, u8 *iv, int enc)
> if (req->cryptlen > SA_MAX_DATA_SZ ||
> (req->cryptlen >= SA_UNSAFE_DATA_SZ_MIN &&
> req->cryptlen <= SA_UNSAFE_DATA_SZ_MAX)) {
> - SYNC_SKCIPHER_REQUEST_ON_STACK(subreq, ctx->fallback.skcipher);
> + struct skcipher_request *subreq = skcipher_request_ctx(req);
>
> - skcipher_request_set_sync_tfm(subreq, ctx->fallback.skcipher);
> + skcipher_request_set_tfm(subreq, ctx->fallback.skcipher);
> skcipher_request_set_callback(subreq, req->base.flags,
> - NULL, NULL);
> + req->base.complete,
> + req->base.data);
> skcipher_request_set_crypt(subreq, req->src, req->dst,
> req->cryptlen, req->iv);
> if (enc)
> - ret = crypto_skcipher_encrypt(subreq);
> + return crypto_skcipher_encrypt(subreq);
> else
> - ret = crypto_skcipher_decrypt(subreq);
> -
> - skcipher_request_zero(subreq);
> - return ret;
> + return crypto_skcipher_decrypt(subreq);
> }
>
> sa_req.size = req->cryptlen;
> diff --git a/drivers/crypto/sa2ul.h b/drivers/crypto/sa2ul.h
> index 7f7e3fe60d11..bb40df3876e5 100644
> --- a/drivers/crypto/sa2ul.h
> +++ b/drivers/crypto/sa2ul.h
> @@ -12,10 +12,8 @@
> #ifndef _K3_SA2UL_
> #define _K3_SA2UL_
>
> -#include <linux/interrupt.h>
> -#include <linux/skbuff.h>
> -#include <linux/hw_random.h>
> #include <crypto/aes.h>
> +#include <crypto/sha.h>
>
> #define SA_ENGINE_ENABLE_CONTROL 0x1000
>
> @@ -311,7 +309,7 @@ struct sa_tfm_ctx {
> struct crypto_shash *shash;
> /* for fallback */
> union {
> - struct crypto_sync_skcipher *skcipher;
> + struct crypto_skcipher *skcipher;
> struct crypto_ahash *ahash;
> struct crypto_aead *aead;
> } fallback;
>
--
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