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crypto: aegis128 - avoid function pointers for parameterization
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Instead of passing around an ops structure with function pointers,
which forces indirect calls to be used, refactor the code slightly
so we can use ordinary function calls. At the same time, switch to
a static key to decide whether or not the SIMD code path may be used.

Signed-off-by: Ard Biesheuvel <[email protected]>
Signed-off-by: Herbert Xu <[email protected]>
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@herbertx
Ard Biesheuvel authored and herbertx committed Oct 25, 2019
1 parent be867f9 commit 2698bce
Showing 1 changed file with 46 additions and 59 deletions.
105 changes: 46 additions & 59 deletions crypto/aegis128-core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@
#include <crypto/scatterwalk.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/jump_label.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/scatterlist.h>
Expand All @@ -35,15 +36,7 @@ struct aegis_ctx {
union aegis_block key;
};

struct aegis128_ops {
int (*skcipher_walk_init)(struct skcipher_walk *walk,
struct aead_request *req, bool atomic);

void (*crypt_chunk)(struct aegis_state *state, u8 *dst,
const u8 *src, unsigned int size);
};

static bool have_simd;
static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_simd);

static const union aegis_block crypto_aegis_const[2] = {
{ .words64 = {
Expand All @@ -59,7 +52,7 @@ static const union aegis_block crypto_aegis_const[2] = {
static bool aegis128_do_simd(void)
{
#ifdef CONFIG_CRYPTO_AEGIS128_SIMD
if (have_simd)
if (static_branch_likely(&have_simd))
return crypto_simd_usable();
#endif
return false;
Expand Down Expand Up @@ -323,25 +316,27 @@ static void crypto_aegis128_process_ad(struct aegis_state *state,
}
}

static void crypto_aegis128_process_crypt(struct aegis_state *state,
struct aead_request *req,
const struct aegis128_ops *ops)
static __always_inline
int crypto_aegis128_process_crypt(struct aegis_state *state,
struct aead_request *req,
struct skcipher_walk *walk,
void (*crypt)(struct aegis_state *state,
u8 *dst, const u8 *src,
unsigned int size))
{
struct skcipher_walk walk;
int err = 0;

ops->skcipher_walk_init(&walk, req, false);
while (walk->nbytes) {
unsigned int nbytes = walk->nbytes;

while (walk.nbytes) {
unsigned int nbytes = walk.nbytes;
if (nbytes < walk->total)
nbytes = round_down(nbytes, walk->stride);

if (nbytes < walk.total)
nbytes = round_down(nbytes, walk.stride);
crypt(state, walk->dst.virt.addr, walk->src.virt.addr, nbytes);

ops->crypt_chunk(state, walk.dst.virt.addr, walk.src.virt.addr,
nbytes);

skcipher_walk_done(&walk, walk.nbytes - nbytes);
err = skcipher_walk_done(walk, walk->nbytes - nbytes);
}
return err;
}

static void crypto_aegis128_final(struct aegis_state *state,
Expand Down Expand Up @@ -390,39 +385,27 @@ static int crypto_aegis128_setauthsize(struct crypto_aead *tfm,
return 0;
}

static void crypto_aegis128_crypt(struct aead_request *req,
union aegis_block *tag_xor,
unsigned int cryptlen,
const struct aegis128_ops *ops)
static int crypto_aegis128_encrypt(struct aead_request *req)
{
struct crypto_aead *tfm = crypto_aead_reqtfm(req);
union aegis_block tag = {};
unsigned int authsize = crypto_aead_authsize(tfm);
struct aegis_ctx *ctx = crypto_aead_ctx(tfm);
unsigned int cryptlen = req->cryptlen;
struct skcipher_walk walk;
struct aegis_state state;

crypto_aegis128_init(&state, &ctx->key, req->iv);
crypto_aegis128_process_ad(&state, req->src, req->assoclen);
crypto_aegis128_process_crypt(&state, req, ops);
crypto_aegis128_final(&state, tag_xor, req->assoclen, cryptlen);
}

static int crypto_aegis128_encrypt(struct aead_request *req)
{
const struct aegis128_ops *ops = &(struct aegis128_ops){
.skcipher_walk_init = skcipher_walk_aead_encrypt,
.crypt_chunk = crypto_aegis128_encrypt_chunk,
};

struct crypto_aead *tfm = crypto_aead_reqtfm(req);
union aegis_block tag = {};
unsigned int authsize = crypto_aead_authsize(tfm);
unsigned int cryptlen = req->cryptlen;

skcipher_walk_aead_encrypt(&walk, req, false);
if (aegis128_do_simd())
ops = &(struct aegis128_ops){
.skcipher_walk_init = skcipher_walk_aead_encrypt,
.crypt_chunk = crypto_aegis128_encrypt_chunk_simd };

crypto_aegis128_crypt(req, &tag, cryptlen, ops);
crypto_aegis128_process_crypt(&state, req, &walk,
crypto_aegis128_encrypt_chunk_simd);
else
crypto_aegis128_process_crypt(&state, req, &walk,
crypto_aegis128_encrypt_chunk);
crypto_aegis128_final(&state, &tag, req->assoclen, cryptlen);

scatterwalk_map_and_copy(tag.bytes, req->dst, req->assoclen + cryptlen,
authsize, 1);
Expand All @@ -431,26 +414,29 @@ static int crypto_aegis128_encrypt(struct aead_request *req)

static int crypto_aegis128_decrypt(struct aead_request *req)
{
const struct aegis128_ops *ops = &(struct aegis128_ops){
.skcipher_walk_init = skcipher_walk_aead_decrypt,
.crypt_chunk = crypto_aegis128_decrypt_chunk,
};
static const u8 zeros[AEGIS128_MAX_AUTH_SIZE] = {};

struct crypto_aead *tfm = crypto_aead_reqtfm(req);
union aegis_block tag;
unsigned int authsize = crypto_aead_authsize(tfm);
unsigned int cryptlen = req->cryptlen - authsize;
struct aegis_ctx *ctx = crypto_aead_ctx(tfm);
struct skcipher_walk walk;
struct aegis_state state;

scatterwalk_map_and_copy(tag.bytes, req->src, req->assoclen + cryptlen,
authsize, 0);

if (aegis128_do_simd())
ops = &(struct aegis128_ops){
.skcipher_walk_init = skcipher_walk_aead_decrypt,
.crypt_chunk = crypto_aegis128_decrypt_chunk_simd };
crypto_aegis128_init(&state, &ctx->key, req->iv);
crypto_aegis128_process_ad(&state, req->src, req->assoclen);

crypto_aegis128_crypt(req, &tag, cryptlen, ops);
skcipher_walk_aead_decrypt(&walk, req, false);
if (aegis128_do_simd())
crypto_aegis128_process_crypt(&state, req, &walk,
crypto_aegis128_decrypt_chunk_simd);
else
crypto_aegis128_process_crypt(&state, req, &walk,
crypto_aegis128_decrypt_chunk);
crypto_aegis128_final(&state, &tag, req->assoclen, cryptlen);

return crypto_memneq(tag.bytes, zeros, authsize) ? -EBADMSG : 0;
}
Expand Down Expand Up @@ -481,8 +467,9 @@ static struct aead_alg crypto_aegis128_alg = {

static int __init crypto_aegis128_module_init(void)
{
if (IS_ENABLED(CONFIG_CRYPTO_AEGIS128_SIMD))
have_simd = crypto_aegis128_have_simd();
if (IS_ENABLED(CONFIG_CRYPTO_AEGIS128_SIMD) &&
crypto_aegis128_have_simd())
static_branch_enable(&have_simd);

return crypto_register_aead(&crypto_aegis128_alg);
}
Expand Down

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