From f9dc9f2e4072de356614d95940c9d7f448a4e334 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Wed, 18 Oct 2023 22:53:33 -0700 Subject: [PATCH] crypto: cmac - remove unnecessary alignment logic The cmac template is setting its alignmask to that of its underlying 'cipher'. Yet, it doesn't care itself about how its inputs and outputs are aligned, which is ostensibly the point of the alignmask. Instead, cmac actually just uses its alignmask itself to runtime-align certain fields in its tfm and desc contexts appropriately for its underlying cipher. That is almost entirely pointless too, though, since cmac is already using the cipher API functions that handle alignment themselves, and few ciphers set a nonzero alignmask anyway. Also, even without runtime alignment, an alignment of at least 4 bytes can be guaranteed. Thus, at best this code is optimizing for the rare case of ciphers that set an alignmask >= 7, at the cost of hurting the common cases. Therefore, this patch removes the manual alignment code from cmac and makes it stop setting an alignmask. Signed-off-by: Eric Biggers Signed-off-by: Herbert Xu --- crypto/cmac.c | 39 +++++++++++---------------------------- 1 file changed, 11 insertions(+), 28 deletions(-) diff --git a/crypto/cmac.c b/crypto/cmac.c index fce6b0f58e88..c7aa3665b076 100644 --- a/crypto/cmac.c +++ b/crypto/cmac.c @@ -28,7 +28,7 @@ */ struct cmac_tfm_ctx { struct crypto_cipher *child; - u8 ctx[]; + __be64 consts[]; }; /* @@ -44,17 +44,15 @@ struct cmac_tfm_ctx { */ struct cmac_desc_ctx { unsigned int len; - u8 ctx[]; + u8 odds[]; }; static int crypto_cmac_digest_setkey(struct crypto_shash *parent, const u8 *inkey, unsigned int keylen) { - unsigned long alignmask = crypto_shash_alignmask(parent); struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent); unsigned int bs = crypto_shash_blocksize(parent); - __be64 *consts = PTR_ALIGN((void *)ctx->ctx, - (alignmask | (__alignof__(__be64) - 1)) + 1); + __be64 *consts = ctx->consts; u64 _const[2]; int i, err = 0; u8 msb_mask, gfmask; @@ -104,10 +102,9 @@ static int crypto_cmac_digest_setkey(struct crypto_shash *parent, static int crypto_cmac_digest_init(struct shash_desc *pdesc) { - unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm); struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc); int bs = crypto_shash_blocksize(pdesc->tfm); - u8 *prev = PTR_ALIGN((void *)ctx->ctx, alignmask + 1) + bs; + u8 *prev = &ctx->odds[bs]; ctx->len = 0; memset(prev, 0, bs); @@ -119,12 +116,11 @@ static int crypto_cmac_digest_update(struct shash_desc *pdesc, const u8 *p, unsigned int len) { struct crypto_shash *parent = pdesc->tfm; - unsigned long alignmask = crypto_shash_alignmask(parent); struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent); struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc); struct crypto_cipher *tfm = tctx->child; int bs = crypto_shash_blocksize(parent); - u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1); + u8 *odds = ctx->odds; u8 *prev = odds + bs; /* checking the data can fill the block */ @@ -165,14 +161,11 @@ static int crypto_cmac_digest_update(struct shash_desc *pdesc, const u8 *p, static int crypto_cmac_digest_final(struct shash_desc *pdesc, u8 *out) { struct crypto_shash *parent = pdesc->tfm; - unsigned long alignmask = crypto_shash_alignmask(parent); struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent); struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc); struct crypto_cipher *tfm = tctx->child; int bs = crypto_shash_blocksize(parent); - u8 *consts = PTR_ALIGN((void *)tctx->ctx, - (alignmask | (__alignof__(__be64) - 1)) + 1); - u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1); + u8 *odds = ctx->odds; u8 *prev = odds + bs; unsigned int offset = 0; @@ -191,7 +184,7 @@ static int crypto_cmac_digest_final(struct shash_desc *pdesc, u8 *out) } crypto_xor(prev, odds, bs); - crypto_xor(prev, consts + offset, bs); + crypto_xor(prev, (const u8 *)tctx->consts + offset, bs); crypto_cipher_encrypt_one(tfm, out, prev); @@ -241,7 +234,6 @@ static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb) struct shash_instance *inst; struct crypto_cipher_spawn *spawn; struct crypto_alg *alg; - unsigned long alignmask; u32 mask; int err; @@ -273,23 +265,14 @@ static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb) if (err) goto err_free_inst; - alignmask = alg->cra_alignmask; - inst->alg.base.cra_alignmask = alignmask; inst->alg.base.cra_priority = alg->cra_priority; inst->alg.base.cra_blocksize = alg->cra_blocksize; + inst->alg.base.cra_ctxsize = sizeof(struct cmac_tfm_ctx) + + alg->cra_blocksize * 2; inst->alg.digestsize = alg->cra_blocksize; - inst->alg.descsize = - ALIGN(sizeof(struct cmac_desc_ctx), crypto_tfm_ctx_alignment()) - + (alignmask & ~(crypto_tfm_ctx_alignment() - 1)) - + alg->cra_blocksize * 2; - - inst->alg.base.cra_ctxsize = - ALIGN(sizeof(struct cmac_tfm_ctx), crypto_tfm_ctx_alignment()) - + ((alignmask | (__alignof__(__be64) - 1)) & - ~(crypto_tfm_ctx_alignment() - 1)) - + alg->cra_blocksize * 2; - + inst->alg.descsize = sizeof(struct cmac_desc_ctx) + + alg->cra_blocksize * 2; inst->alg.init = crypto_cmac_digest_init; inst->alg.update = crypto_cmac_digest_update; inst->alg.final = crypto_cmac_digest_final;