On Wednesday 08 July 2015 09:48 AM, Herbert Xu wrote:
> 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?
Sorry, I missed it. Ill update.
>
>> +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.
Ill take care of this.
>
>> +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.
Ok, Ill use rctx. Thanks for pointing.
>
>> + 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?
Why not? Self tests are passed for this case.
As per the equation given in GCM spec[1], we can see that
if assoclen and cryptlen is 0, then output of GCM is just E(K, Y0)
where Y0 = IV||(0^31)1
I have E(K, Y0) calculated in previous step. And copying it
to destination if assoclen and cryptlen is 0.
Correct me if I am wrong.
Thanks and regards,
Lokesh
[1] http://csrc.nist.gov/groups/ST/toolkit/BCM/documents/proposedmodes/gcm/gcm-revised-spec.pdf
>
> Cheers,
>
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