On Sun, Apr 30, 2023 at 10:52 PM Martin KaFai Lau <martin.lau@xxxxxxxxx> wrote: > > On 4/27/23 1:04 PM, Stanislav Fomichev wrote: > > @@ -1881,8 +1886,10 @@ int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level, > > .optname = optname, > > .current_task = current, > > }; > > + int orig_optlen; > > int ret; > > > > + orig_optlen = max_optlen; > > For getsockopt, when the kernel's getsockopt finished successfully (the > following 'if (!retval)' case), how about also setting orig_optlen to the kernel > returned 'optlen'. For example, the user's orig_optlen is 8096 and the kernel > returned optlen is 1024. If the bpf prog still sets the ctx.optlen to something > > PAGE_SIZE, -EFAULT will be returned. Wouldn't it defeat the purpose? Or am I missing something? ctx.optlen would still be 8096, not 1024, right (regardless of what the kernel returns)? So it would trigger EFAULT case which we try to avoid.
