> -----Original Message-----
> From: Dave Watson [mailto:davejwat...@fb.com]
> Sent: Tuesday, August 7, 2018 8:26 PM
> To: Vakul Garg <vakul.g...@nxp.com>
> Cc: netdev@vger.kernel.org; bor...@mellanox.com;
> avia...@mellanox.com; da...@davemloft.net
> Subject: Re: [PATCH RFC net-next 1/1] net/tls: Combined memory allocation
> for decryption request
>
> Hi Vakul,
>
> Only minor comments, mostly looks good to me. Thanks
>
> > +/* This function decrypts the input skb into either out_iov or in
> > +out_sg
> > + * or in skb buffers itself. The input parameter 'zc' indicates if
> > + * zero-copy mode needs to be tried or not. With zero-copy mode,
> > +either
> > + * out_iov or out_sg must be non-NULL. In case both out_iov and
> > +out_sg are
> > + * NULL, then the decryption happens inside skb buffers itself, i.e.
> > + * zero-copy gets disabled and 'zc' is updated.
> > + */
> > +
> > +static int decrypt_internal(struct sock *sk, struct sk_buff *skb,
> > + struct iov_iter *out_iov,
> > + struct scatterlist *out_sg,
> > + int *chunk, bool *zc)
> > +{
> > + struct tls_context *tls_ctx = tls_get_ctx(sk);
> > + struct tls_sw_context_rx *ctx = tls_sw_ctx_rx(tls_ctx);
> > + struct strp_msg *rxm = strp_msg(skb);
> > + int n_sgin, n_sgout, nsg, mem_size, aead_size, err, pages = 0;
> > + struct aead_request *aead_req;
> > + struct sk_buff *unused;
> > + u8 *aad, *iv, *mem = NULL;
> > + struct scatterlist *sgin = NULL;
> > + struct scatterlist *sgout = NULL;
> > + const int data_len = rxm->full_len - tls_ctx->rx.overhead_size;
> > +
> > + if (*zc && (out_iov || out_sg)) {
> > + if (out_iov)
> > + n_sgout = iov_iter_npages(out_iov, INT_MAX) + 1;
> > + else if (out_sg)
> > + n_sgout = sg_nents(out_sg);
> > + else
> > + goto no_zerocopy;
>
> Is the last else necessary? It looks like the if already checks for out_iov
> ||
> out_sg.
>
You are right. I can remove 'else. 'else if' can also be replaced with 'else'.
I would submit v2.
> > struct scatterlist *sgout)
> > {
> > - struct tls_context *tls_ctx = tls_get_ctx(sk);
> > - struct tls_sw_context_rx *ctx = tls_sw_ctx_rx(tls_ctx);
> > - char iv[TLS_CIPHER_AES_GCM_128_SALT_SIZE + MAX_IV_SIZE];
> > - struct scatterlist sgin_arr[MAX_SKB_FRAGS + 2];
> > - struct scatterlist *sgin = &sgin_arr[0];
> > - struct strp_msg *rxm = strp_msg(skb);
> > - int ret, nsg;
> > - struct sk_buff *unused;
> > -
> > - ret = skb_copy_bits(skb, rxm->offset + TLS_HEADER_SIZE,
> > - iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE,
> > - tls_ctx->rx.iv_size);
> > - if (ret < 0)
> > - return ret;
> > -
> > - memcpy(iv, tls_ctx->rx.iv, TLS_CIPHER_AES_GCM_128_SALT_SIZE);
> > - if (!sgout) {
> > - nsg = skb_cow_data(skb, 0, &unused);
> > - } else {
> > - nsg = skb_nsg(skb,
> > - rxm->offset + tls_ctx->rx.prepend_size,
> > - rxm->full_len - tls_ctx->rx.prepend_size);
> > - if (nsg <= 0)
> > - return nsg;
> > - }
> > -
> > - // We need one extra for ctx->rx_aad_ciphertext
> > - nsg++;
> > -
> > - if (nsg > ARRAY_SIZE(sgin_arr))
> > - sgin = kmalloc_array(nsg, sizeof(*sgin), sk->sk_allocation);
> > -
> > - if (!sgout)
> > - sgout = sgin;
> > -
> > - sg_init_table(sgin, nsg);
> > - sg_set_buf(&sgin[0], ctx->rx_aad_ciphertext, TLS_AAD_SPACE_SIZE);
> > -
> > - nsg = skb_to_sgvec(skb, &sgin[1],
> > - rxm->offset + tls_ctx->rx.prepend_size,
> > - rxm->full_len - tls_ctx->rx.prepend_size);
> > - if (nsg < 0) {
> > - ret = nsg;
> > - goto out;
> > - }
> > -
> > - tls_make_aad(ctx->rx_aad_ciphertext,
> > - rxm->full_len - tls_ctx->rx.overhead_size,
> > - tls_ctx->rx.rec_seq,
> > - tls_ctx->rx.rec_seq_size,
> > - ctx->control);
> > -
> > - ret = tls_do_decryption(sk, sgin, sgout, iv,
> > - rxm->full_len - tls_ctx->rx.overhead_size,
> > - skb, sk->sk_allocation);
> > -
> > -out:
> > - if (sgin != &sgin_arr[0])
> > - kfree(sgin);
> > + bool zc = true;
> > + int chunk;
> >
> > - return ret;
> > + return decrypt_internal(sk, skb, NULL, sgout, &chunk, &zc);
> > }
>
> Can we merge this function to callsites? It's pretty useless now.
I retained decrypt_skb() in its existing prototype to keep the caller
in tls_device.c unmodified. It seemed simpler that way to me
from code readability perspective in tls_device.c.
Let me know if this would prevent getting your ack for the patch :).
> >
> > static bool tls_sw_advance_skb(struct sock *sk, struct sk_buff *skb,
> > @@ -899,43 +964,17 @@ int tls_sw_recvmsg(struct sock *sk,
> > }
> >
> > if (!ctx->decrypted) {
> > - int page_count;
> > - int to_copy;
