On Fri, Sep 04, 2020 at 04:31:44PM -0400, Gabriel Krisman Bertazi wrote: > Syscall User Dispatch (SUD) must take precedence over seccomp, since the > use case is emulation (it can be invoked with a different ABI) such that > seccomp filtering by syscall number doesn't make sense in the first > place. In addition, either the syscall is dispatched back to userspace, > in which case there is no resource for seccomp to protect, or the > syscall will be executed, and seccomp will execute next. > > Regarding ptrace, I experimented with before and after, and while the > same ABI argument applies, I felt it was easier to debug if I let ptrace > happen for syscalls that are dispatched back to userspace. In addition, > doing it after ptrace makes the code in syscall_exit_work slightly > simpler, since it doesn't require special handling for this feature. I think I'm with Andy that this should be before ptrace(). ptrace() users will attempt to interpret things like they're regular syscalls, and that's definitely not the case.
