crypto: ccm - move cbcmac input off the stack

Commit f15f05b0a5de ("crypto: ccm - switch to separate cbcmac driver")
refactored the CCM driver to allow separate implementations of the
underlying MAC to be provided by a platform. However, in doing so, it
moved some data from the linear region to the stack, which violates the
SG constraints when the stack is virtually mapped.

So move idata/odata back to the request ctx struct, of which we can
reasonably expect that it has been allocated using kmalloc() et al.

Reported-by: Johannes Berg <johannes@sipsolutions.net>
Fixes: f15f05b0a5de ("crypto: ccm - switch to separate cbcmac driver")
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
static struct aead_request *crypto_rfc4309_crypt(struct aead_request *req)
{
	struct crypto_rfc4309_req_ctx *rctx = aead_request_ctx(req);
	struct aead_request *subreq = &rctx->subreq;
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(aead);
	struct crypto_aead *child = ctx->child;
	struct scatterlist *sg;
	u8 *iv = PTR_ALIGN((u8 *)(subreq + 1) + crypto_aead_reqsize(child),
			   crypto_aead_alignmask(child) + 1);

	/* L' */
	iv[0] = 3;

	memcpy(iv + 1, ctx->nonce, 3);
	memcpy(iv + 4, req->iv, 8);

	scatterwalk_map_and_copy(iv + 16, req->src, 0, req->assoclen - 8, 0);

	sg_init_table(rctx->src, 3);
	sg_set_buf(rctx->src, iv + 16, req->assoclen - 8);
	sg = scatterwalk_ffwd(rctx->src + 1, req->src, req->assoclen);
	if (sg != rctx->src + 1)
		sg_chain(rctx->src, 2, sg);

	if (req->src != req->dst) {
		sg_init_table(rctx->dst, 3);
		sg_set_buf(rctx->dst, iv + 16, req->assoclen - 8);
		sg = scatterwalk_ffwd(rctx->dst + 1, req->dst, req->assoclen);
		if (sg != rctx->dst + 1)
			sg_chain(rctx->dst, 2, sg);
	}

	aead_request_set_tfm(subreq, child);
	aead_request_set_callback(subreq, req->base.flags, req->base.complete,
				  req->base.data);
	aead_request_set_crypt(subreq, rctx->src,
			       req->src == req->dst ? rctx->src : rctx->dst,
			       req->cryptlen, iv);
	aead_request_set_ad(subreq, req->assoclen - 8);

	return subreq;
}

static struct aead_request *crypto_rfc4309_crypt(struct aead_request *req)
{
	struct crypto_rfc4309_req_ctx *rctx = aead_request_ctx(req);
	struct aead_request *subreq = &rctx->subreq;
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct crypto_rfc4309_ctx *ctx = crypto_aead_ctx(aead);
	struct crypto_aead *child = ctx->child;
	struct scatterlist *sg;
	u8 *iv = PTR_ALIGN((u8 *)(subreq + 1) + crypto_aead_reqsize(child),
			   crypto_aead_alignmask(child) + 1);

	/* L' */
	iv[0] = 3;

	memcpy(iv + 1, ctx->nonce, 3);
	memcpy(iv + 4, req->iv, 8);

	scatterwalk_map_and_copy(iv + 16, req->src, 0, req->assoclen - 8, 0);

	sg_init_table(rctx->src, 3);
	sg_set_buf(rctx->src, iv + 16, req->assoclen - 8);
	sg = scatterwalk_ffwd(rctx->src + 1, req->src, req->assoclen);
	if (sg != rctx->src + 1)
		sg_chain(rctx->src, 2, sg);

	if (req->src != req->dst) {
		sg_init_table(rctx->dst, 3);
		sg_set_buf(rctx->dst, iv + 16, req->assoclen - 8);
		sg = scatterwalk_ffwd(rctx->dst + 1, req->dst, req->assoclen);
		if (sg != rctx->dst + 1)
			sg_chain(rctx->dst, 2, sg);
	}

	aead_request_set_tfm(subreq, child);
	aead_request_set_callback(subreq, req->base.flags, req->base.complete,
				  req->base.data);
	aead_request_set_crypt(subreq, rctx->src,
			       req->src == req->dst ? rctx->src : rctx->dst,
			       req->cryptlen, iv);
	aead_request_set_ad(subreq, req->assoclen - 8);

	return subreq;
}
