On Tue, Jan 5, 2016 at 12:38 PM, Eric Dumazet <eric.duma...@gmail.com> wrote:
> On Tue, 2016-01-05 at 10:57 -0500, Craig Gallek wrote:
>> From: Craig Gallek <kr...@google.com>
>>
>> Fixes: 538950a1b752 ("soreuseport: setsockopt SO_ATTACH_REUSEPORT_[CE]BPF")
>> Suggested-by: Daniel Borkmann <dan...@iogearbox.net>
>> Signed-off-by: Craig Gallek <kr...@google.com>
>> ---
>> net/core/sock_reuseport.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/core/sock_reuseport.c b/net/core/sock_reuseport.c
>> index ae0969c0fc2e..1df98c557440 100644
>> --- a/net/core/sock_reuseport.c
>> +++ b/net/core/sock_reuseport.c
>> @@ -173,7 +173,7 @@ static struct sock *run_bpf(struct sock_reuseport
>> *reuse, u16 socks,
>>
>> /* temporarily advance data past protocol header */
>> if (!pskb_pull(skb, hdr_len)) {
>> - consume_skb(nskb);
>> + kfree_skb(nskb);
>> return NULL;
>> }
>> index = bpf_prog_run_save_cb(prog, skb);
>
> Note that we always call reuseport_select_sock() after pulling the
> headers in skb->head anyway, so the pskb_pull() can never fail.
>
> It really could be __skb_pull()
>
> BTW, why UDP calls reuseport_select_sock() with hdr_len == 0 sometimes ?
hdr_len only matters when you have an skb to work with. In both of
the call sites of your suggested patch, NULL is passed for the skb
parameter so hdr_len is never used. When no skb is available, the
code falls back to the hash-based method used in the non-BPF case.
> I believe the following patch is needed.
>
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 835378365f25..52387096dbba 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -514,7 +514,8 @@ begin:
> struct sock *sk2;
> hash = udp_ehashfn(net, daddr, hnum,
> saddr, sport);
> - sk2 = reuseport_select_sock(sk, hash, NULL,
> 0);
> + sk2 = reuseport_select_sock(sk, hash, NULL,
> + sizeof(struct
> udphdr));
> if (sk2) {
> result = sk2;
> goto found;
> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> index 56fcb55fda31..da0a5fa02b0f 100644
> --- a/net/ipv6/udp.c
> +++ b/net/ipv6/udp.c
> @@ -272,7 +272,8 @@ begin:
> struct sock *sk2;
> hash = udp6_ehashfn(net, daddr, hnum,
> saddr, sport);
> - sk2 = reuseport_select_sock(sk, hash, NULL,
> 0);
> + sk2 = reuseport_select_sock(sk, hash, NULL,
> + sizeof(struct
> udphdr));
> if (sk2) {
> result = sk2;
> goto found;
>
>
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