Messages in this thread | | | From | Andy Lutomirski <> | Date | Thu, 16 Jul 2020 17:20:02 -0700 | Subject | Re: [PATCH v4 1/2] kernel: Implement selective syscall userspace redirection |
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On Thu, Jul 16, 2020 at 12:31 PM Gabriel Krisman Bertazi <krisman@collabora.com> wrote: >
This is quite nice. I have a few comments, though:
You mentioned rt_sigreturn(). Should this automatically exempt the kernel-provided signal restorer on architectures (e.g. x86_32) that provide one?
The amount of syscall entry wiring that arches need to do is IMO already a bit out of hand. Should we instead rename TIF_SECCOMP to TIF_SYSCALL_INTERCEPTION and have one generic callback that handles seccomp and this new thing?
> +int do_syscall_user_dispatch(struct pt_regs *regs) > +{ > + struct syscall_user_dispatch *sd = ¤t->syscall_dispatch; > + unsigned long ip = instruction_pointer(regs); > + char state; > + > + if (likely(ip >= sd->dispatcher_start && ip <= sd->dispatcher_end)) > + return 0; > + > + if (likely(sd->selector)) { > + if (unlikely(__get_user(state, sd->selector))) > + do_exit(SIGSEGV); > + > + if (likely(state == 0)) > + return 0; > + > + if (state != 1) > + do_exit(SIGSEGV);
This seems a bit extreme and hard to debug if it ever happens.
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