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crypto: gcm - use memcpy_sglist() instead of null skcipher

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For copying data between two scatterlists, just use memcpy_sglist()
instead of the so-called "null skcipher".  This is much simpler.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Eric Biggers 2025-05-05 12:10:40 -07:00 • committed by Herbert Xu
parent dbc4b1458e
commit 4e39d0712e
2 changed files with 4 additions and 38 deletions
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1
crypto/Kconfig
View file

@ -805,7 +805,6 @@ config CRYPTO_GCM
select CRYPTO_CTR
select CRYPTO_AEAD
select CRYPTO_GHASH
select CRYPTO_NULL
select CRYPTO_MANAGER
help
GCM (Galois/Counter Mode) authenticated encryption mode and GMAC

41
crypto/gcm.c
View file

@ -9,7 +9,6 @@
#include <crypto/internal/aead.h>
#include <crypto/internal/skcipher.h>
#include <crypto/internal/hash.h>
#include <crypto/null.h>
#include <crypto/scatterwalk.h>
#include <crypto/gcm.h>
#include <crypto/hash.h>
@ -46,7 +45,6 @@ struct crypto_rfc4543_instance_ctx {
struct crypto_rfc4543_ctx {
struct crypto_aead *child;
struct crypto_sync_skcipher *null;
u8 nonce[4];
};
@ -79,8 +77,6 @@ static struct {
struct scatterlist sg;
} *gcm_zeroes;
static int crypto_rfc4543_copy_src_to_dst(struct aead_request *req, bool enc);
static inline struct crypto_gcm_req_priv_ctx *crypto_gcm_reqctx(
struct aead_request *req)
{
@ -930,12 +926,12 @@ static int crypto_rfc4543_crypt(struct aead_request *req, bool enc)
unsigned int authsize = crypto_aead_authsize(aead);
u8 *iv = PTR_ALIGN((u8 *)(rctx + 1) + crypto_aead_reqsize(ctx->child),
crypto_aead_alignmask(ctx->child) + 1);
int err;
if (req->src != req->dst) {
err = crypto_rfc4543_copy_src_to_dst(req, enc);
if (err)
return err;
unsigned int nbytes = req->assoclen + req->cryptlen -
(enc ? 0 : authsize);
memcpy_sglist(req->dst, req->src, nbytes);
}
memcpy(iv, ctx->nonce, 4);
@ -952,22 +948,6 @@ static int crypto_rfc4543_crypt(struct aead_request *req, bool enc)
return enc ? crypto_aead_encrypt(subreq) : crypto_aead_decrypt(subreq);
}
static int crypto_rfc4543_copy_src_to_dst(struct aead_request *req, bool enc)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct crypto_rfc4543_ctx *ctx = crypto_aead_ctx(aead);
unsigned int authsize = crypto_aead_authsize(aead);
unsigned int nbytes = req->assoclen + req->cryptlen -
(enc ? 0 : authsize);
SYNC_SKCIPHER_REQUEST_ON_STACK(nreq, ctx->null);
skcipher_request_set_sync_tfm(nreq, ctx->null);
skcipher_request_set_callback(nreq, req->base.flags, NULL, NULL);
skcipher_request_set_crypt(nreq, req->src, req->dst, nbytes, NULL);
return crypto_skcipher_encrypt(nreq);
}
static int crypto_rfc4543_encrypt(struct aead_request *req)
{
return crypto_ipsec_check_assoclen(req->assoclen) ?:
@ -987,21 +967,13 @@ static int crypto_rfc4543_init_tfm(struct crypto_aead *tfm)
struct crypto_aead_spawn *spawn = &ictx->aead;
struct crypto_rfc4543_ctx *ctx = crypto_aead_ctx(tfm);
struct crypto_aead *aead;
struct crypto_sync_skcipher *null;
unsigned long align;
int err = 0;
aead = crypto_spawn_aead(spawn);
if (IS_ERR(aead))
return PTR_ERR(aead);
null = crypto_get_default_null_skcipher();
err = PTR_ERR(null);
if (IS_ERR(null))
goto err_free_aead;
ctx->child = aead;
ctx->null = null;
align = crypto_aead_alignmask(aead);
align &= ~(crypto_tfm_ctx_alignment() - 1);
@ -1012,10 +984,6 @@ static int crypto_rfc4543_init_tfm(struct crypto_aead *tfm)
align + GCM_AES_IV_SIZE);
return 0;
err_free_aead:
crypto_free_aead(aead);
return err;
}
static void crypto_rfc4543_exit_tfm(struct crypto_aead *tfm)
@ -1023,7 +991,6 @@ static void crypto_rfc4543_exit_tfm(struct crypto_aead *tfm)
struct crypto_rfc4543_ctx *ctx = crypto_aead_ctx(tfm);
crypto_free_aead(ctx->child);
crypto_put_default_null_skcipher();
}
static void crypto_rfc4543_free(struct aead_instance *inst)