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[CRYPTO] gcm: Add support for async ciphers
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This patch adds the necessary changes for GCM to be used with async
ciphers.  This would allow it to be used with hardware devices that
support CTR.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Herbert Xu committed Jan 10, 2008
1 parent 5311f24 commit 84c9115
Showing 1 changed file with 112 additions and 78 deletions.
190 changes: 112 additions & 78 deletions crypto/gcm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@
#include <crypto/algapi.h>
#include <crypto/gf128mul.h>
#include <crypto/scatterwalk.h>
#include <linux/completion.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
Expand Down Expand Up @@ -38,11 +39,17 @@ struct crypto_gcm_ghash_ctx {
struct crypto_gcm_req_priv_ctx {
u8 auth_tag[16];
u8 iauth_tag[16];
u8 counter[16];
struct scatterlist src[2];
struct scatterlist dst[2];
struct crypto_gcm_ghash_ctx ghash;
struct ablkcipher_request abreq;
};

struct crypto_gcm_setkey_result {
int err;
struct completion completion;
};

static inline struct crypto_gcm_req_priv_ctx *crypto_gcm_reqctx(
struct aead_request *req)
{
Expand Down Expand Up @@ -158,107 +165,119 @@ static void crypto_gcm_ghash_final_xor(struct crypto_gcm_ghash_ctx *ctx,
crypto_xor(dst, buf, 16);
}

static inline void crypto_gcm_set_counter(u8 *counterblock, u32 value)
static void crypto_gcm_setkey_done(struct crypto_async_request *req, int err)
{
*((u32 *)&counterblock[12]) = cpu_to_be32(value + 1);
}
struct crypto_gcm_setkey_result *result = req->data;

static int crypto_gcm_encrypt_counter(struct crypto_aead *aead, u8 *block,
u32 value, const u8 *iv)
{
struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);
struct crypto_ablkcipher *ctr = ctx->ctr;
struct ablkcipher_request req;
struct scatterlist sg;
u8 counterblock[16];

if (iv == NULL)
memset(counterblock, 0, 12);
else
memcpy(counterblock, iv, 12);

crypto_gcm_set_counter(counterblock, value);

sg_init_one(&sg, block, 16);
ablkcipher_request_set_tfm(&req, ctr);
ablkcipher_request_set_crypt(&req, &sg, &sg, 16, counterblock);
ablkcipher_request_set_callback(&req, 0, NULL, NULL);
memset(block, 0, 16);
return crypto_ablkcipher_encrypt(&req);
if (err == -EINPROGRESS)
return;

result->err = err;
complete(&result->completion);
}

static int crypto_gcm_setkey(struct crypto_aead *aead, const u8 *key,
unsigned int keylen)
{
struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);
struct crypto_ablkcipher *ctr = ctx->ctr;
int alignmask = crypto_ablkcipher_alignmask(ctr);
u8 alignbuf[16+alignmask];
u8 *hash = (u8 *)ALIGN((unsigned long)alignbuf, alignmask+1);
int err = 0;
struct {
be128 hash;
u8 iv[8];

struct crypto_gcm_setkey_result result;

struct scatterlist sg[1];
struct ablkcipher_request req;
} *data;
int err;

crypto_ablkcipher_clear_flags(ctr, CRYPTO_TFM_REQ_MASK);
crypto_ablkcipher_set_flags(ctr, crypto_aead_get_flags(aead) &
CRYPTO_TFM_REQ_MASK);

err = crypto_ablkcipher_setkey(ctr, key, keylen);
if (err)
goto out;
return err;

crypto_aead_set_flags(aead, crypto_ablkcipher_get_flags(ctr) &
CRYPTO_TFM_RES_MASK);

err = crypto_gcm_encrypt_counter(aead, hash, -1, NULL);
data = kzalloc(sizeof(*data) + crypto_ablkcipher_reqsize(ctr),
GFP_KERNEL);
if (!data)
return -ENOMEM;

init_completion(&data->result.completion);
sg_init_one(data->sg, &data->hash, sizeof(data->hash));
ablkcipher_request_set_tfm(&data->req, ctr);
ablkcipher_request_set_callback(&data->req, CRYPTO_TFM_REQ_MAY_SLEEP |
CRYPTO_TFM_REQ_MAY_BACKLOG,
crypto_gcm_setkey_done,
&data->result);
ablkcipher_request_set_crypt(&data->req, data->sg, data->sg,
sizeof(data->hash), data->iv);

err = crypto_ablkcipher_encrypt(&data->req);
if (err == -EINPROGRESS || err == -EBUSY) {
err = wait_for_completion_interruptible(
&data->result.completion);
if (!err)
err = data->result.err;
}

if (err)
goto out;

if (ctx->gf128 != NULL)
gf128mul_free_4k(ctx->gf128);

ctx->gf128 = gf128mul_init_4k_lle((be128 *)hash);
ctx->gf128 = gf128mul_init_4k_lle(&data->hash);

if (ctx->gf128 == NULL)
err = -ENOMEM;

out:
out:
kfree(data);
return err;
}

static int crypto_gcm_init_crypt(struct ablkcipher_request *ablk_req,
struct aead_request *req,
unsigned int cryptlen,
void (*done)(struct crypto_async_request *,
int))
static void crypto_gcm_init_crypt(struct ablkcipher_request *ablk_req,
struct aead_request *req,
unsigned int cryptlen)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);
struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
u32 flags = req->base.tfm->crt_flags;
u8 *auth_tag = pctx->auth_tag;
u8 *counter = pctx->counter;
struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
int err = 0;
struct scatterlist *dst;
__be32 counter = cpu_to_be32(1);

memset(pctx->auth_tag, 0, sizeof(pctx->auth_tag));
memcpy(req->iv + 12, &counter, 4);

sg_init_table(pctx->src, 2);
sg_set_buf(pctx->src, pctx->auth_tag, sizeof(pctx->auth_tag));
scatterwalk_sg_chain(pctx->src, 2, req->src);

dst = pctx->src;
if (req->src != req->dst) {
sg_init_table(pctx->dst, 2);
sg_set_buf(pctx->dst, pctx->auth_tag, sizeof(pctx->auth_tag));
scatterwalk_sg_chain(pctx->dst, 2, req->dst);
dst = pctx->dst;
}

ablkcipher_request_set_tfm(ablk_req, ctx->ctr);
ablkcipher_request_set_callback(ablk_req, aead_request_flags(req),
done, req);
ablkcipher_request_set_crypt(ablk_req, req->src, req->dst,
cryptlen, counter);

err = crypto_gcm_encrypt_counter(aead, auth_tag, 0, req->iv);
if (err)
goto out;

memcpy(counter, req->iv, 12);
crypto_gcm_set_counter(counter, 1);
ablkcipher_request_set_crypt(ablk_req, pctx->src, dst,
cryptlen + sizeof(pctx->auth_tag),
req->iv);

crypto_gcm_ghash_init(ghash, flags, ctx->gf128);

crypto_gcm_ghash_update_sg(ghash, req->assoc, req->assoclen);
crypto_gcm_ghash_flush(ghash);

out:
return err;
}

static int crypto_gcm_hash(struct aead_request *req)
Expand Down Expand Up @@ -291,34 +310,51 @@ static int crypto_gcm_encrypt(struct aead_request *req)
{
struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
struct ablkcipher_request *abreq = &pctx->abreq;
int err = 0;
int err;

crypto_gcm_init_crypt(abreq, req, req->cryptlen);
ablkcipher_request_set_callback(abreq, aead_request_flags(req),
crypto_gcm_encrypt_done, req);

err = crypto_gcm_init_crypt(abreq, req, req->cryptlen,
crypto_gcm_encrypt_done);
err = crypto_ablkcipher_encrypt(abreq);
if (err)
return err;

if (req->cryptlen) {
err = crypto_ablkcipher_encrypt(abreq);
if (err)
return err;
}

return crypto_gcm_hash(req);
}

static int crypto_gcm_verify(struct aead_request *req)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
u8 *auth_tag = pctx->auth_tag;
u8 *iauth_tag = pctx->iauth_tag;
unsigned int authsize = crypto_aead_authsize(aead);
unsigned int cryptlen = req->cryptlen - authsize;

crypto_gcm_ghash_final_xor(ghash, req->assoclen, cryptlen, auth_tag);

authsize = crypto_aead_authsize(aead);
scatterwalk_map_and_copy(iauth_tag, req->src, cryptlen, authsize, 0);
return memcmp(iauth_tag, auth_tag, authsize) ? -EBADMSG : 0;
}

static void crypto_gcm_decrypt_done(struct crypto_async_request *areq, int err)
{
aead_request_complete(areq->data, err);
struct aead_request *req = areq->data;

if (!err)
err = crypto_gcm_verify(req);

aead_request_complete(req, err);
}

static int crypto_gcm_decrypt(struct aead_request *req)
{
struct crypto_aead *aead = crypto_aead_reqtfm(req);
struct crypto_gcm_req_priv_ctx *pctx = crypto_gcm_reqctx(req);
struct ablkcipher_request *abreq = &pctx->abreq;
u8 *auth_tag = pctx->auth_tag;
u8 *iauth_tag = pctx->iauth_tag;
struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
unsigned int cryptlen = req->cryptlen;
unsigned int authsize = crypto_aead_authsize(aead);
Expand All @@ -328,19 +364,17 @@ static int crypto_gcm_decrypt(struct aead_request *req)
return -EINVAL;
cryptlen -= authsize;

err = crypto_gcm_init_crypt(abreq, req, cryptlen,
crypto_gcm_decrypt_done);
if (err)
return err;
crypto_gcm_init_crypt(abreq, req, cryptlen);
ablkcipher_request_set_callback(abreq, aead_request_flags(req),
crypto_gcm_decrypt_done, req);

crypto_gcm_ghash_update_sg(ghash, req->src, cryptlen);
crypto_gcm_ghash_final_xor(ghash, req->assoclen, cryptlen, auth_tag);

scatterwalk_map_and_copy(iauth_tag, req->src, cryptlen, authsize, 0);
if (memcmp(iauth_tag, auth_tag, authsize))
return -EBADMSG;
err = crypto_ablkcipher_decrypt(abreq);
if (err)
return err;

return crypto_ablkcipher_decrypt(abreq);
return crypto_gcm_verify(req);
}

static int crypto_gcm_init_tfm(struct crypto_tfm *tfm)
Expand Down Expand Up @@ -436,7 +470,7 @@ static struct crypto_instance *crypto_gcm_alloc(struct rtattr **tb)
inst->alg.cra_blocksize = 16;
inst->alg.cra_alignmask = ctr->cra_alignmask | (__alignof__(u64) - 1);
inst->alg.cra_type = &crypto_aead_type;
inst->alg.cra_aead.ivsize = 12;
inst->alg.cra_aead.ivsize = 16;
inst->alg.cra_aead.maxauthsize = 16;
inst->alg.cra_ctxsize = sizeof(struct crypto_gcm_ctx);
inst->alg.cra_init = crypto_gcm_init_tfm;
Expand Down

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