On Thu, May 07, 2015 at 05:44:53PM +0800, Yao Dongdong wrote:
> while we use crypto api for userspace to do vectors test for AEAD(aes-gcm),
> we encounter a problem. There are some test vector's PTlen is 0,for example:
> [Keylen = 128]
> [IVlen = 96]
> [PTlen = 0]
> [AADlen = 0]
> [Taglen = 128]
>
> Count = 0
> Key = 7e93936b2e2188cfa9c9882ad901312f
> IV = b6879804163b9eaf5bfe5218
> CT =
> AAD =
> Tag = aa77daf382d0d63480ff8c8a2dee149e
>
> In testing vectors like that, we will get an error result that the decrypt
> return is success but the right return is a ghash verify fail.
> After digging into the kernel(3.10) code, we find the function sock_aio_read
> in net/socket.c has a judgement of iocb->ki_left which will be 0 when we
> do an aes-gcm decrypt decribed above.
>
> static ssize_t sock_aio_read(struct kiocb *iocb, const struct iovec *iov,
> unsigned long nr_segs, loff_t pos)
> {
> struct sock_iocb siocb, *x;
>
> if (pos != 0)
> return -ESPIPE;
>
> if (iocb->ki_left == 0) /* Match SYS5 behaviour */
> return 0;
>
> x = alloc_sock_iocb(iocb, &siocb);
> if (!x)
> return -ENOMEM;
> return do_sock_read(&x->async_msg, iocb, iocb->ki_filp, iov, nr_segs);
> }
>
> So it directly return before calling aes-gcm decrypt.
>
> How can we deal with that?
Does this still happen if you use recvmsg?
Cheers,
--
Email: Herbert Xu <herb...@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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