24-28 August 2020
US/Pacific timezone

seccomp feature development

26 Aug 2020, 09:00
45m
Refereed Track/Virtual-Room (LPC 2020)

Refereed Track/Virtual-Room

LPC 2020

150
Kernel Summit Kernel Summit

Speaker

Kees Cook (Google)

Description

As outlined in https://lore.kernel.org/lkml/202005181120.971232B7B@keescook/ the topics include:

  • fd passing
  • deep argument inspection
  • changing structure sizes
  • syscall bitmasks

Specifically, seccomp needs to grow the ability to inspect Extensible Argument syscalls, which requires that it inspect userspace memory without Time-of-Check/Time-of-Use races and without double-copying. Additionally, since the structures can grow and be nested, there needs to be a way to deal with flattening the arguments into a linear buffer that can be examined by seccomp's BPF dialect. All of this also needs to be handled by the USER_NOTIF implementation. Finally, fd passing needs to be finished, and there needs to be an exploration of syscall bitmasks to augment the existing filters to gain back some performance.

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Primary author

Kees Cook (Google)

Presentation Materials