[CRYPTO] gcm: Add support for async ciphers

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>

crypto/gcm.c

@@ -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>
@@ -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)
 {
@@ -158,33 +165,15 @@ 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,
@@ -192,10 +181,16 @@ static int crypto_gcm_setkey(struct crypto_aead *aead, const u8 *key,
 {
 	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) &
@@ -203,62 +198,86 @@ static int crypto_gcm_setkey(struct crypto_aead *aead, const u8 *key,
 
 	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,
+static void crypto_gcm_init_crypt(struct ablkcipher_request *ablk_req,
 				  struct aead_request *req,
-				 unsigned int cryptlen,
-				 void (*done)(struct crypto_async_request *,
-					      int))
+				  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)
@@ -291,25 +310,44 @@ 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;
 
-	err = crypto_gcm_init_crypt(abreq, req, req->cryptlen,
-				    crypto_gcm_encrypt_done);
-	if (err)
-		return err;
+	crypto_gcm_init_crypt(abreq, req, req->cryptlen);
+	ablkcipher_request_set_callback(abreq, aead_request_flags(req),
+					crypto_gcm_encrypt_done, req);
 
-	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)
@@ -317,8 +355,6 @@ 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);
@@ -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)
@@ -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;