On Wed, May 10, 2023 at 4:32 PM Stanislav Fomichev <sdf@xxxxxxxxxx> wrote: > > On Wed, May 10, 2023 at 6:15 AM Alexander Mikhalitsyn > <aleksandr.mikhalitsyn@xxxxxxxxxxxxx> wrote: > > > > Add bpf_bypass_getsockopt proto callback and filter out > > SCTP_SOCKOPT_PEELOFF and SCTP_SOCKOPT_PEELOFF_FLAGS socket options > > from running eBPF hook on them. > > > > These options do fd_install(), and if BPF_CGROUP_RUN_PROG_GETSOCKOPT > > hook returns an error after success of the original handler > > sctp_getsockopt(...), userspace will receive an error from getsockopt > > syscall and will be not aware that fd was successfully installed into fdtable. > > > > This patch was born as a result of discussion around a new SCM_PIDFD interface: > > https://lore.kernel.org/all/20230413133355.350571-3-aleksandr.mikhalitsyn@xxxxxxxxxxxxx/ > > > > Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks") > > Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx> > > Cc: Christian Brauner <brauner@xxxxxxxxxx> > > Cc: Stanislav Fomichev <sdf@xxxxxxxxxx> > > Cc: Neil Horman <nhorman@xxxxxxxxxxxxx> > > Cc: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx> > > Cc: Xin Long <lucien.xin@xxxxxxxxx> > > Cc: linux-sctp@xxxxxxxxxxxxxxx > > Cc: linux-kernel@xxxxxxxxxxxxxxx > > Cc: netdev@xxxxxxxxxxxxxxx > > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@xxxxxxxxxxxxx> > > Acked-by: Stanislav Fomichev <sdf@xxxxxxxxxx> > > with a small nit below Hi Stanislav! Thanks for your review. I've also added a Suggested-by tag with your name in -v2, because you've given me this idea to use bpf_bypass_getsockopt. Hope that you are comfortable with it. > > > --- > > net/sctp/socket.c | 25 +++++++++++++++++++++++++ > > 1 file changed, 25 insertions(+) > > > > diff --git a/net/sctp/socket.c b/net/sctp/socket.c > > index cda8c2874691..a9a0ababea90 100644 > > --- a/net/sctp/socket.c > > +++ b/net/sctp/socket.c > > @@ -8281,6 +8281,29 @@ static int sctp_getsockopt(struct sock *sk, int level, int optname, > > return retval; > > } > > > > [...] > > > +bool sctp_bpf_bypass_getsockopt(int level, int optname) > > static bool ... ? You're not making it indirect-callable, so seems > fine to keep private to this compilation unit? Sure, my bad. Fixed in v2. Kind regards, Alex > > > +{ > > + /* > > + * These options do fd_install(), and if BPF_CGROUP_RUN_PROG_GETSOCKOPT > > + * hook returns an error after success of the original handler > > + * sctp_getsockopt(...), userspace will receive an error from getsockopt > > + * syscall and will be not aware that fd was successfully installed into fdtable. > > + * > > + * Let's prevent bpf cgroup hook from running on them. > > + */ > > + if (level == SOL_SCTP) { > > + switch (optname) { > > + case SCTP_SOCKOPT_PEELOFF: > > + case SCTP_SOCKOPT_PEELOFF_FLAGS: > > + return true; > > + default: > > + return false; > > + } > > + } > > + > > + return false; > > +} > > + > > static int sctp_hash(struct sock *sk) > > { > > /* STUB */ > > @@ -9650,6 +9673,7 @@ struct proto sctp_prot = { > > .shutdown = sctp_shutdown, > > .setsockopt = sctp_setsockopt, > > .getsockopt = sctp_getsockopt, > > + .bpf_bypass_getsockopt = sctp_bpf_bypass_getsockopt, > > .sendmsg = sctp_sendmsg, > > .recvmsg = sctp_recvmsg, > > .bind = sctp_bind, > > @@ -9705,6 +9729,7 @@ struct proto sctpv6_prot = { > > .shutdown = sctp_shutdown, > > .setsockopt = sctp_setsockopt, > > .getsockopt = sctp_getsockopt, > > + .bpf_bypass_getsockopt = sctp_bpf_bypass_getsockopt, > > .sendmsg = sctp_sendmsg, > > .recvmsg = sctp_recvmsg, > > .bind = sctp_bind, > > -- > > 2.34.1 > >
