Skip to content

Commit

Permalink
[CRYPTO] gcm: Add support for async ciphers
Browse files Browse the repository at this point in the history 
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 <[email protected]>
  • Loading branch information
@herbertx
herbertx 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
View file
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

0 comments on commit 84c9115

Please sign in to comment.