[CRYPTO] gcm: New algorithm

Add GCM/GMAC support to cryptoapi.

GCM (Galois/Counter Mode) is an AEAD mode of operations for any block cipher
with a block size of 16.  The typical example is AES-GCM.

Signed-off-by: Mikko Herranen <mh1@iki.fi>
Reviewed-by: Mika Kukkonen <mika.kukkonen@nsn.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 465 insertions, 0 deletions

diff --git a/crypto/gcm.c b/crypto/gcm.c
new file mode 100644
index 0000000..ad8b8b9
--- /dev/null
+++ b/crypto/gcm.c
@@ -0,0 +1,465 @@
+/*
+ * GCM: Galois/Counter Mode.
+ *
+ * Copyright (c) 2007 Nokia Siemens Networks - Mikko Herranen <mh1@iki.fi>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <crypto/algapi.h>
+#include <crypto/gf128mul.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include "scatterwalk.h"
+
+struct gcm_instance_ctx {
+	struct crypto_spawn ctr;
+};
+
+struct crypto_gcm_ctx {
+	struct crypto_ablkcipher *ctr;
+	struct gf128mul_4k *gf128;
+};
+
+struct crypto_gcm_ghash_ctx {
+	u32 bytes;
+	u32 flags;
+	struct gf128mul_4k *gf128;
+	u8 buffer[16];
+};
+
+struct crypto_gcm_req_priv_ctx {
+	u8 auth_tag[16];
+	u8 counter[16];
+	struct crypto_gcm_ghash_ctx ghash;
+};
+
+static void crypto_gcm_ghash_init(struct crypto_gcm_ghash_ctx *ctx, u32 flags,
+				  struct gf128mul_4k *gf128)
+{
+	ctx->bytes = 0;
+	ctx->flags = flags;
+	ctx->gf128 = gf128;
+	memset(ctx->buffer, 0, 16);
+}
+
+static void crypto_gcm_ghash_update(struct crypto_gcm_ghash_ctx *ctx,
+				    const u8 *src, unsigned int srclen)
+{
+	u8 *dst = ctx->buffer;
+
+	if (ctx->bytes) {
+		int n = min(srclen, ctx->bytes);
+		u8 *pos = dst + (16 - ctx->bytes);
+
+		ctx->bytes -= n;
+		srclen -= n;
+
+		while (n--)
+			*pos++ ^= *src++;
+
+		if (!ctx->bytes)
+			gf128mul_4k_lle((be128 *)dst, ctx->gf128);
+	}
+
+	while (srclen >= 16) {
+		crypto_xor(dst, src, 16);
+		gf128mul_4k_lle((be128 *)dst, ctx->gf128);
+		src += 16;
+		srclen -= 16;
+	}
+
+	if (srclen) {
+		ctx->bytes = 16 - srclen;
+		while (srclen--)
+			*dst++ ^= *src++;
+	}
+}
+
+static void crypto_gcm_ghash_update_sg(struct crypto_gcm_ghash_ctx *ctx,
+				       struct scatterlist *sg, int len)
+{
+	struct scatter_walk walk;
+	u8 *src;
+	int n;
+
+	scatterwalk_start(&walk, sg);
+
+	while (len) {
+		n = scatterwalk_clamp(&walk, len);
+
+		if (!n) {
+			scatterwalk_start(&walk, sg_next(walk.sg));
+			n = scatterwalk_clamp(&walk, len);
+		}
+
+		src = scatterwalk_map(&walk, 0);
+
+		crypto_gcm_ghash_update(ctx, src, n);
+		len -= n;
+
+		scatterwalk_unmap(src, 0);
+		scatterwalk_advance(&walk, n);
+		scatterwalk_done(&walk, 0, len);
+		if (len)
+			crypto_yield(ctx->flags);
+	}
+}
+
+static void crypto_gcm_ghash_flush(struct crypto_gcm_ghash_ctx *ctx)
+{
+	u8 *dst = ctx->buffer;
+
+	if (ctx->bytes) {
+		u8 *tmp = dst + (16 - ctx->bytes);
+
+		while (ctx->bytes--)
+			*tmp++ ^= 0;
+
+		gf128mul_4k_lle((be128 *)dst, ctx->gf128);
+	}
+
+	ctx->bytes = 0;
+}
+
+static void crypto_gcm_ghash_final_xor(struct crypto_gcm_ghash_ctx *ctx,
+				       unsigned int authlen,
+				       unsigned int cryptlen, u8 *dst)
+{
+	u8 *buf = ctx->buffer;
+	u128 lengths;
+
+	lengths.a = cpu_to_be64(authlen * 8);
+	lengths.b = cpu_to_be64(cryptlen * 8);
+
+	crypto_gcm_ghash_flush(ctx);
+	crypto_xor(buf, (u8 *)&lengths, 16);
+	gf128mul_4k_lle((be128 *)buf, ctx->gf128);
+	crypto_xor(dst, buf, 16);
+}
+
+static inline void crypto_gcm_set_counter(u8 *counterblock, u32 value)
+{
+	*((u32 *)&counterblock[12]) = cpu_to_be32(value);
+}
+
+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);
+}
+
+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;
+
+	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;
+
+	crypto_aead_set_flags(aead, crypto_ablkcipher_get_flags(ctr) &
+				       CRYPTO_TFM_RES_MASK);
+
+	err = crypto_gcm_encrypt_counter(aead, hash, -1, NULL);
+	if (err)
+		goto out;
+
+	if (ctx->gf128 != NULL)
+		gf128mul_free_4k(ctx->gf128);
+
+	ctx->gf128 = gf128mul_init_4k_lle((be128 *)hash);
+
+	if (ctx->gf128 == NULL)
+		err = -ENOMEM;
+
+ out:
+	return err;
+}
+
+static int crypto_gcm_init_crypt(struct ablkcipher_request *ablk_req,
+				  struct aead_request *req,
+				  void (*done)(struct crypto_async_request *,
+					       int))
+{
+	struct crypto_aead *aead = crypto_aead_reqtfm(req);
+	struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);
+	struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(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;
+
+	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,
+				     req->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);
+
+	crypto_gcm_ghash_init(ghash, flags, ctx->gf128);
+
+	if (req->assoclen) {
+		crypto_gcm_ghash_update_sg(ghash, req->assoc, req->assoclen);
+		crypto_gcm_ghash_flush(ghash);
+	}
+
+ out:
+	return err;
+}
+
+static void crypto_gcm_encrypt_done(struct crypto_async_request *areq, int err)
+{
+	struct aead_request *req = areq->data;
+	struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(req);
+	u8 *auth_tag = pctx->auth_tag;
+	struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
+
+	crypto_gcm_ghash_update_sg(ghash, req->dst, req->cryptlen);
+	crypto_gcm_ghash_final_xor(ghash, req->assoclen, req->cryptlen,
+				   auth_tag);
+
+	aead_request_complete(req, err);
+}
+
+static int crypto_gcm_encrypt(struct aead_request *req)
+{
+	struct ablkcipher_request abreq;
+	struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(req);
+	u8 *auth_tag = pctx->auth_tag;
+	struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
+	int err = 0;
+
+	err = crypto_gcm_init_crypt(&abreq, req, crypto_gcm_encrypt_done);
+	if (err)
+		return err;
+
+	if (req->cryptlen) {
+		err = crypto_ablkcipher_encrypt(&abreq);
+		if (err)
+			return err;
+
+		crypto_gcm_ghash_update_sg(ghash, req->dst, req->cryptlen);
+	}
+
+	crypto_gcm_ghash_final_xor(ghash, req->assoclen, req->cryptlen,
+				   auth_tag);
+
+	return err;
+}
+
+static void crypto_gcm_decrypt_done(struct crypto_async_request *areq, int err)
+{
+	aead_request_complete(areq->data, err);
+}
+
+static int crypto_gcm_decrypt(struct aead_request *req)
+{
+	struct ablkcipher_request abreq;
+	struct crypto_gcm_req_priv_ctx *pctx = aead_request_ctx(req);
+	u8 *auth_tag = pctx->auth_tag;
+	struct crypto_gcm_ghash_ctx *ghash = &pctx->ghash;
+	u8 tag[16];
+	int err;
+
+	if (!req->cryptlen)
+		return -EINVAL;
+
+	memcpy(tag, auth_tag, 16);
+	err = crypto_gcm_init_crypt(&abreq, req, crypto_gcm_decrypt_done);
+	if (err)
+		return err;
+
+	crypto_gcm_ghash_update_sg(ghash, req->src, req->cryptlen);
+	crypto_gcm_ghash_final_xor(ghash, req->assoclen, req->cryptlen,
+				   auth_tag);
+
+	if (memcmp(tag, auth_tag, 16))
+		return -EINVAL;
+
+	return crypto_ablkcipher_decrypt(&abreq);
+}
+
+static int crypto_gcm_init_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_instance *inst = (void *)tfm->__crt_alg;
+	struct gcm_instance_ctx *ictx = crypto_instance_ctx(inst);
+	struct crypto_gcm_ctx *ctx = crypto_tfm_ctx(tfm);
+	struct crypto_ablkcipher *ctr;
+	unsigned long align;
+	int err;
+
+	ctr = crypto_spawn_ablkcipher(&ictx->ctr);
+	err = PTR_ERR(ctr);
+	if (IS_ERR(ctr))
+		return err;
+
+	ctx->ctr = ctr;
+	ctx->gf128 = NULL;
+
+	align = max_t(unsigned long, crypto_ablkcipher_alignmask(ctr),
+		      __alignof__(u32) - 1);
+	align &= ~(crypto_tfm_ctx_alignment() - 1);
+	tfm->crt_aead.reqsize = align + sizeof(struct crypto_gcm_req_priv_ctx);
+
+	return 0;
+}
+
+static void crypto_gcm_exit_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_gcm_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	if (ctx->gf128 != NULL)
+		gf128mul_free_4k(ctx->gf128);
+
+	crypto_free_ablkcipher(ctx->ctr);
+}
+
+static struct crypto_instance *crypto_gcm_alloc(struct rtattr **tb)
+{
+	struct crypto_instance *inst;
+	struct crypto_alg *ctr;
+	struct crypto_alg *cipher;
+	struct gcm_instance_ctx *ctx;
+	int err;
+	char ctr_name[CRYPTO_MAX_ALG_NAME];
+
+	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AEAD);
+	if (err)
+		return ERR_PTR(err);
+
+	cipher = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
+			      CRYPTO_ALG_TYPE_MASK);
+
+	inst = ERR_PTR(PTR_ERR(cipher));
+	if (IS_ERR(cipher))
+		return inst;
+
+	inst = ERR_PTR(ENAMETOOLONG);
+	if (snprintf(
+		    ctr_name, CRYPTO_MAX_ALG_NAME,
+		    "ctr(%s,0,16,4)", cipher->cra_name) >= CRYPTO_MAX_ALG_NAME)
+		return inst;
+
+	ctr = crypto_alg_mod_lookup(ctr_name, CRYPTO_ALG_TYPE_BLKCIPHER,
+				    CRYPTO_ALG_TYPE_MASK);
+
+	if (IS_ERR(ctr))
+		return ERR_PTR(PTR_ERR(ctr));
+
+	if (cipher->cra_blocksize != 16)
+		goto out_put_ctr;
+
+	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
+	err = -ENOMEM;
+	if (!inst)
+		goto out_put_ctr;
+
+	err = -ENAMETOOLONG;
+	if (snprintf(inst->alg.cra_name, CRYPTO_MAX_ALG_NAME,
+		     "gcm(%s)", cipher->cra_name) >= CRYPTO_MAX_ALG_NAME ||
+	    snprintf(inst->alg.cra_driver_name, CRYPTO_MAX_ALG_NAME,
+		     "gcm(%s)", cipher->cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
+		goto err_free_inst;
+
+
+	ctx = crypto_instance_ctx(inst);
+	err = crypto_init_spawn(&ctx->ctr, ctr, inst, CRYPTO_ALG_TYPE_MASK);
+	if (err)
+		goto err_free_inst;
+
+	inst->alg.cra_flags = CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_ASYNC;
+	inst->alg.cra_priority = ctr->cra_priority;
+	inst->alg.cra_blocksize = 16;
+	inst->alg.cra_alignmask = __alignof__(u32) - 1;
+	inst->alg.cra_type = &crypto_aead_type;
+	inst->alg.cra_aead.ivsize = 12;
+	inst->alg.cra_aead.authsize = 16;
+	inst->alg.cra_ctxsize = sizeof(struct crypto_gcm_ctx);
+	inst->alg.cra_init = crypto_gcm_init_tfm;
+	inst->alg.cra_exit = crypto_gcm_exit_tfm;
+	inst->alg.cra_aead.setkey = crypto_gcm_setkey;
+	inst->alg.cra_aead.encrypt = crypto_gcm_encrypt;
+	inst->alg.cra_aead.decrypt = crypto_gcm_decrypt;
+
+out:
+	crypto_mod_put(ctr);
+	return inst;
+err_free_inst:
+	kfree(inst);
+out_put_ctr:
+	inst = ERR_PTR(err);
+	goto out;
+}
+
+static void crypto_gcm_free(struct crypto_instance *inst)
+{
+	struct gcm_instance_ctx *ctx = crypto_instance_ctx(inst);
+
+	crypto_drop_spawn(&ctx->ctr);
+	kfree(inst);
+}
+
+static struct crypto_template crypto_gcm_tmpl = {
+	.name = "gcm",
+	.alloc = crypto_gcm_alloc,
+	.free = crypto_gcm_free,
+	.module = THIS_MODULE,
+};
+
+static int __init crypto_gcm_module_init(void)
+{
+	return crypto_register_template(&crypto_gcm_tmpl);
+}
+
+static void __exit crypto_gcm_module_exit(void)
+{
+	crypto_unregister_template(&crypto_gcm_tmpl);
+}
+
+module_init(crypto_gcm_module_init);
+module_exit(crypto_gcm_module_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Galois/Counter Mode");
+MODULE_AUTHOR("Mikko Herranen <mh1@iki.fi>");