On Wed, Aug 03, 2022 at 04:30:54PM -0700, sdf@xxxxxxxxxx wrote:
> > +struct sock_common {
> > + unsigned short skc_family;
> > + unsigned long skc_flags;
> > + unsigned char skc_reuse:4;
> > + unsigned char skc_reuseport:1;
> > + unsigned char skc_ipv6only:1;
> > + unsigned char skc_net_refcnt:1;
> > +} __attribute__((preserve_access_index));
> > +
> > +struct sock {
> > + struct sock_common __sk_common;
> > + __u16 sk_type;
> > + __u16 sk_protocol;
> > + int sk_rcvlowat;
> > + __u32 sk_mark;
> > + unsigned long sk_max_pacing_rate;
> > + unsigned int keepalive_time;
> > + unsigned int keepalive_intvl;
> > +} __attribute__((preserve_access_index));
> > +
> > +struct tcp_options_received {
> > + __u16 user_mss;
> > +} __attribute__((preserve_access_index));
>
> I'm assuming you're not using vmlinux here because it doesn't bring
> it most of the defines? Should we add missing stuff to bpf_tracing_net.h
> instead?
Ah, actually my first attempt was to use vmlinux.h and had
all defines ready for addition to bpf_tracing_net.h.
However, I hit an issue in reading bitfield. It is why the
bitfield in the tcp_sock below is sandwiched between __u32.
I think it is likely LLVM and/or CO-RE related. Yonghong is
helping to investigate it.
In the mean time, I define those mini struct here.
Once the bitfield issue is resolved, we can go back to
use vmlinux.h.
>
> > +struct ipv6_pinfo {
> > + __u16 recverr:1,
> > + sndflow:1,
> > + repflow:1,
> > + pmtudisc:3,
> > + padding:1,
> > + srcprefs:3,
> > + dontfrag:1,
> > + autoflowlabel:1,
> > + autoflowlabel_set:1,
> > + mc_all:1,
> > + recverr_rfc4884:1,
> > + rtalert_isolate:1;
> > +} __attribute__((preserve_access_index));
> > +
> > +struct inet_sock {
> > + /* sk and pinet6 has to be the first two members of inet_sock */
> > + struct sock sk;
> > + struct ipv6_pinfo *pinet6;
> > +} __attribute__((preserve_access_index));
> > +
> > +struct inet_connection_sock {
> > + __u32 icsk_user_timeout;
> > + __u8 icsk_syn_retries;
> > +} __attribute__((preserve_access_index));
> > +
> > +struct tcp_sock {
> > + struct inet_connection_sock inet_conn;
> > + struct tcp_options_received rx_opt;
> > + __u8 save_syn:2,
> > + syn_data:1,
> > + syn_fastopen:1,
> > + syn_fastopen_exp:1,
> > + syn_fastopen_ch:1,
> > + syn_data_acked:1,
> > + is_cwnd_limited:1;
> > + __u32 window_clamp;
> > + __u8 nonagle : 4,
> > + thin_lto : 1,
> > + recvmsg_inq : 1,
> > + repair : 1,
> > + frto : 1;
> > + __u32 notsent_lowat;
> > + __u8 keepalive_probes;
> > + unsigned int keepalive_time;
> > + unsigned int keepalive_intvl;
> > +} __attribute__((preserve_access_index));
> > +
> > +struct socket {
> > + struct sock *sk;
> > +} __attribute__((preserve_access_index));
> > +
> > +struct loop_ctx {
> > + void *ctx;
> > + struct sock *sk;
> > +};
> > +
> > +static int __bpf_getsockopt(void *ctx, struct sock *sk,
> > + int level, int opt, int *optval,
> > + int optlen)
> > +{
> > + if (level == SOL_SOCKET) {
> > + switch (opt) {
> > + case SO_REUSEADDR:
> > + *optval = !!(sk->__sk_common.skc_reuse);
> > + break;
> > + case SO_KEEPALIVE:
> > + *optval = !!(sk->__sk_common.skc_flags & (1UL << 3));
> > + break;
> > + case SO_RCVLOWAT:
> > + *optval = sk->sk_rcvlowat;
> > + break;
>
> What's the idea with the options above? Why not allow them in
> bpf_getsockopt instead?
I am planning to refactor the bpf_getsockopt also,
so trying to avoid adding more dup code at this point
while they can directly be read from sk through PTR_TO_BTF_ID.
btw, since we are on bpf_getsockopt(), do you still see a usage on
bpf_getsockopt() for those 'integer-value' optnames that can be
easily read from the sk pointer ?
>
> > + case SO_MARK:
> > + *optval = sk->sk_mark;
> > + break;
>
> SO_MARK should be handled by bpf_getsockopt ?
Good point, will remove SO_MARK case.
Thanks for the review!
