Re: [PATCH v2 6/7] crypto: omap-aes: Add support for GCM mode

On Tue, Jul 07, 2015 at 09:01:48PM +0530, Lokesh Vutla wrote:

+static int omap_aes_gcm_copy_buffers(struct omap_aes_dev *dd,
+				     struct aead_request *req)
+{
+	void *buf_in;
+	int pages, alen, clen, cryptlen, nsg;
+	struct crypto_aead *aead = crypto_aead_reqtfm(req);
+	unsigned int authlen = crypto_aead_authsize(aead);
+	u32 dec = !(dd->flags & FLAGS_ENCRYPT);
+	struct scatterlist *input, *assoc, tmp[2];
+
+	alen = ALIGN(req->assoclen, AES_BLOCK_SIZE);
+	cryptlen = req->cryptlen - (dec * authlen);
+	clen = ALIGN(cryptlen, AES_BLOCK_SIZE);
+
+	dd->sgs_copied = 0;
+
+	nsg = !!(req->assoclen && req->cryptlen);
+
+	assoc = &req->src[0];
+	sg_init_table(dd->in_sgl, nsg + 1);
+	if (req->assoclen) {
+		if (omap_aes_check_aligned(assoc, req->assoclen)) {
+			dd->sgs_copied |= AES_ASSOC_DATA_COPIED;
+			pages = get_order(alen);
+			buf_in = (void *)__get_free_pages(GFP_ATOMIC, pages);
+			if (!buf_in) {
+				pr_err("Couldn't allocate for unaligncases.\n");
+				return -1;
+			}
+
+			scatterwalk_map_and_copy(buf_in, assoc, 0,
+						 req->assoclen, 0);
+			memset(buf_in + req->assoclen, 0, alen - req->assoclen);
+		} else {
+			buf_in = sg_virt(req->assoc);

req->assoc is now obsolete. Did you test this code?

+static int do_encrypt_iv(struct aead_request *req, u32 *tag)
+{
+	struct scatterlist iv_sg;
+	struct ablkcipher_request *ablk_req;
+	struct crypto_ablkcipher *tfm;
+	struct tcrypt_result result;
+	struct omap_aes_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
+	int ret = 0;
+
+	tfm = crypto_alloc_ablkcipher("ctr(aes)", 0, 0);

Ugh, you cannot allocate crypto transforms in the data path.  You
should allocate it in init instead.  Also using ctr(aes) is overkill.
Just use aes and do the xor by hand.

+static int omap_aes_gcm_crypt(struct aead_request *req, unsigned long mode)
+{
+	struct omap_aes_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
+	struct omap_aes_reqctx *rctx = aead_request_ctx(req);
+	struct crypto_aead *aead = crypto_aead_reqtfm(req);
+	unsigned int authlen = crypto_aead_authsize(aead);
+	struct omap_aes_dev *dd;
+	__be32 counter = cpu_to_be32(1);
+	int err;
+
+	memset(ctx->auth_tag, 0, sizeof(ctx->auth_tag));

The ctx is shared memory and you must not write to it as multiple
requests can be called on the same tfm.  Use rctx instead.

+	memcpy(req->iv + 12, &counter, 4);

The IV is only 12 bytes long so you're corrupting memory here.
You should use rctx here too.

+	if (req->assoclen + req->cryptlen == 0) {
+		scatterwalk_map_and_copy(ctx->auth_tag, req->dst, 0, authlen,
+					 1);
+		return 0;
+	}

How can this be right? Did you enable the selftest?

Cheers,
-- 
Email: Herbert Xu [off-list ref]
Home Page: http://gondor.apana.org.au/~herbert/
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