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authorEric Biggers <ebiggers@google.com>2023-10-18 22:53:34 -0700
committerHerbert Xu <herbert@gondor.apana.org.au>2023-10-27 18:04:24 +0800
commit25c74a39e0f637a44982c3820a583755aedc9811 (patch)
tree8524f07e4079099e8f3a39d80dbb223ffe1f96ea
parentf9dc9f2e4072de356614d95940c9d7f448a4e334 (diff)
crypto: hmac - remove unnecessary alignment logic
The hmac template is setting its alignmask to that of its underlying unkeyed hash algorithm, and it is aligning the ipad and opad fields in its tfm context to that alignment. However, hmac does not actually need any sort of alignment itself, which makes this pointless except to keep the pads aligned to what the underlying algorithm prefers. But very few shash algorithms actually set an alignmask, and it is being removed from those remaining ones; also, after setkey, the pads are only passed to crypto_shash_import and crypto_shash_export which ignore the alignmask. Therefore, make the hmac template stop setting an alignmask and simply use natural alignment for ipad and opad. Note, this change also moves the pads from the beginning of the tfm context to the end, which makes much more sense; the variable-length fields should be at the end. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
-rw-r--r--crypto/hmac.c56
1 files changed, 22 insertions, 34 deletions
diff --git a/crypto/hmac.c b/crypto/hmac.c
index ea93f4c55f25..7cec25ff9889 100644
--- a/crypto/hmac.c
+++ b/crypto/hmac.c
@@ -24,31 +24,20 @@
struct hmac_ctx {
struct crypto_shash *hash;
+ /* Contains 'u8 ipad[statesize];', then 'u8 opad[statesize];' */
+ u8 pads[];
};
-static inline void *align_ptr(void *p, unsigned int align)
-{
- return (void *)ALIGN((unsigned long)p, align);
-}
-
-static inline struct hmac_ctx *hmac_ctx(struct crypto_shash *tfm)
-{
- return align_ptr(crypto_shash_ctx_aligned(tfm) +
- crypto_shash_statesize(tfm) * 2,
- crypto_tfm_ctx_alignment());
-}
-
static int hmac_setkey(struct crypto_shash *parent,
const u8 *inkey, unsigned int keylen)
{
int bs = crypto_shash_blocksize(parent);
int ds = crypto_shash_digestsize(parent);
int ss = crypto_shash_statesize(parent);
- char *ipad = crypto_shash_ctx_aligned(parent);
- char *opad = ipad + ss;
- struct hmac_ctx *ctx = align_ptr(opad + ss,
- crypto_tfm_ctx_alignment());
- struct crypto_shash *hash = ctx->hash;
+ struct hmac_ctx *tctx = crypto_shash_ctx(parent);
+ struct crypto_shash *hash = tctx->hash;
+ u8 *ipad = &tctx->pads[0];
+ u8 *opad = &tctx->pads[ss];
SHASH_DESC_ON_STACK(shash, hash);
unsigned int i;
@@ -94,16 +83,18 @@ static int hmac_export(struct shash_desc *pdesc, void *out)
static int hmac_import(struct shash_desc *pdesc, const void *in)
{
struct shash_desc *desc = shash_desc_ctx(pdesc);
- struct hmac_ctx *ctx = hmac_ctx(pdesc->tfm);
+ const struct hmac_ctx *tctx = crypto_shash_ctx(pdesc->tfm);
- desc->tfm = ctx->hash;
+ desc->tfm = tctx->hash;
return crypto_shash_import(desc, in);
}
static int hmac_init(struct shash_desc *pdesc)
{
- return hmac_import(pdesc, crypto_shash_ctx_aligned(pdesc->tfm));
+ const struct hmac_ctx *tctx = crypto_shash_ctx(pdesc->tfm);
+
+ return hmac_import(pdesc, &tctx->pads[0]);
}
static int hmac_update(struct shash_desc *pdesc,
@@ -119,7 +110,8 @@ static int hmac_final(struct shash_desc *pdesc, u8 *out)
struct crypto_shash *parent = pdesc->tfm;
int ds = crypto_shash_digestsize(parent);
int ss = crypto_shash_statesize(parent);
- char *opad = crypto_shash_ctx_aligned(parent) + ss;
+ const struct hmac_ctx *tctx = crypto_shash_ctx(parent);
+ const u8 *opad = &tctx->pads[ss];
struct shash_desc *desc = shash_desc_ctx(pdesc);
return crypto_shash_final(desc, out) ?:
@@ -134,7 +126,8 @@ static int hmac_finup(struct shash_desc *pdesc, const u8 *data,
struct crypto_shash *parent = pdesc->tfm;
int ds = crypto_shash_digestsize(parent);
int ss = crypto_shash_statesize(parent);
- char *opad = crypto_shash_ctx_aligned(parent) + ss;
+ const struct hmac_ctx *tctx = crypto_shash_ctx(parent);
+ const u8 *opad = &tctx->pads[ss];
struct shash_desc *desc = shash_desc_ctx(pdesc);
return crypto_shash_finup(desc, data, nbytes, out) ?:
@@ -147,7 +140,7 @@ static int hmac_init_tfm(struct crypto_shash *parent)
struct crypto_shash *hash;
struct shash_instance *inst = shash_alg_instance(parent);
struct crypto_shash_spawn *spawn = shash_instance_ctx(inst);
- struct hmac_ctx *ctx = hmac_ctx(parent);
+ struct hmac_ctx *tctx = crypto_shash_ctx(parent);
hash = crypto_spawn_shash(spawn);
if (IS_ERR(hash))
@@ -156,14 +149,14 @@ static int hmac_init_tfm(struct crypto_shash *parent)
parent->descsize = sizeof(struct shash_desc) +
crypto_shash_descsize(hash);
- ctx->hash = hash;
+ tctx->hash = hash;
return 0;
}
static int hmac_clone_tfm(struct crypto_shash *dst, struct crypto_shash *src)
{
- struct hmac_ctx *sctx = hmac_ctx(src);
- struct hmac_ctx *dctx = hmac_ctx(dst);
+ struct hmac_ctx *sctx = crypto_shash_ctx(src);
+ struct hmac_ctx *dctx = crypto_shash_ctx(dst);
struct crypto_shash *hash;
hash = crypto_clone_shash(sctx->hash);
@@ -176,9 +169,9 @@ static int hmac_clone_tfm(struct crypto_shash *dst, struct crypto_shash *src)
static void hmac_exit_tfm(struct crypto_shash *parent)
{
- struct hmac_ctx *ctx = hmac_ctx(parent);
+ struct hmac_ctx *tctx = crypto_shash_ctx(parent);
- crypto_free_shash(ctx->hash);
+ crypto_free_shash(tctx->hash);
}
static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
@@ -225,15 +218,10 @@ static int hmac_create(struct crypto_template *tmpl, struct rtattr **tb)
inst->alg.base.cra_priority = alg->cra_priority;
inst->alg.base.cra_blocksize = alg->cra_blocksize;
- inst->alg.base.cra_alignmask = alg->cra_alignmask;
+ inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) + (ss * 2);
- ss = ALIGN(ss, alg->cra_alignmask + 1);
inst->alg.digestsize = ds;
inst->alg.statesize = ss;
-
- inst->alg.base.cra_ctxsize = sizeof(struct hmac_ctx) +
- ALIGN(ss * 2, crypto_tfm_ctx_alignment());
-
inst->alg.init = hmac_init;
inst->alg.update = hmac_update;
inst->alg.final = hmac_final;