On 03/27/2018 07:23 PM, John Fastabend wrote:
> Add support for the BPF_F_INGRESS flag in skb redirect helper. To
> do this convert skb into a scatterlist and push into ingress queue.
> This is the same logic that is used in the sk_msg redirect helper
> so it should feel familiar.
>
> Signed-off-by: John Fastabend <john.fastab...@gmail.com>
> ---
> include/linux/filter.h | 1 +
> kernel/bpf/sockmap.c | 94
> +++++++++++++++++++++++++++++++++++++++---------
> net/core/filter.c | 2 +
> 3 files changed, 78 insertions(+), 19 deletions(-)
[...]
> if (!sg->length && md->sg_start == md->sg_end) {
> list_del(&md->list);
> + if (md->skb)
> + consume_skb(md->skb);
> kfree(md);
> }
> }
> @@ -1045,27 +1048,72 @@ static int smap_verdict_func(struct smap_psock
> *psock, struct sk_buff *skb)
> __SK_DROP;
> }
>
> +static int smap_do_ingress(struct smap_psock *psock, struct sk_buff *skb)
> +{
> + struct sock *sk = psock->sock;
> + int copied = 0, num_sg;
> + struct sk_msg_buff *r;
> +
> + r = kzalloc(sizeof(struct sk_msg_buff), __GFP_NOWARN | GFP_ATOMIC);
> + if (unlikely(!r))
> + return -EAGAIN;
> +
> + if (!sk_rmem_schedule(sk, skb, skb->len)) {
> + kfree(r);
> + return -EAGAIN;
> + }
> + sk_mem_charge(sk, skb->len);
Usually mem accounting is based on truesize. This is not done here since
you need the exact length of the skb for the sg list later on, right?
> + sg_init_table(r->sg_data, MAX_SKB_FRAGS);
> + num_sg = skb_to_sgvec(skb, r->sg_data, 0, skb->len);
> + if (unlikely(num_sg < 0)) {
> + kfree(r);
Don't we need to undo the mem charge here in case of error?
> + return num_sg;
> + }
> + copied = skb->len;
> + r->sg_start = 0;
> + r->sg_end = num_sg == MAX_SKB_FRAGS ? 0 : num_sg;
> + r->skb = skb;
> + list_add_tail(&r->list, &psock->ingress);
> + sk->sk_data_ready(sk);
> + return copied;
> +}
