[RESEND PATCH] crypto: sa2ul - Reduce stack usage

From: Herbert Xu
Date: Wed Oct 14 2020 - 23:32:18 EST

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Resending to linux-crypto.

---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@xxxxxxxxx>
Fixes: d2c8ac187fc9 ("crypto: sa2ul - Add AEAD algorithm support")
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

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;
--
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Next message: Stephen Rothwell: "Re: linux-next: manual merge of the tip tree with the dma-mapping tree"
Previous message: Howard Chung: "[PATCH] mgmt: Add supports of variable length parameter in mgmt_config"
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