Add seccomp notifier ioctl that enables adding fds

Submitted by Kees Cook on July 9, 2020, 6:26 p.m.

Details

Reviewer None
Submitted July 9, 2020, 6:26 p.m.
Last Updated July 10, 2020, 4:27 a.m.
Revision 1

Cover Letter

Hello!

v7:
- break out sock usage counting fixes into more cleanly backportable pieces
- code style cleanups (christian)
- clarify addfd commit log (christian)
- add ..._SIZE_{VER0,LATEST} and BUILD_BUG_ON()s (christian)
- remove undef (christian)
- fix addfd embedded URL reference numbers
v6: https://lore.kernel.org/lkml/20200706201720.3482959-1-keescook@chromium.org/

This continues the thread-merge between [1] and [2]. tl;dr: add a way for
a seccomp user_notif process manager to inject files into the managed
process in order to handle emulation of various fd-returning syscalls
across security boundaries. Containers folks and Chrome are in need
of the feature, and investigating this solution uncovered (and fixed)
implementation issues with existing file sending routines.

I intend to carry this in the for-next/seccomp tree, unless someone
has objections. :) Please review and test!

-Kees

[1] https://lore.kernel.org/lkml/20200603011044.7972-1-sargun@sargun.me/
[2] https://lore.kernel.org/lkml/20200610045214.1175600-1-keescook@chromium.org/


Kees Cook (7):
  net/compat: Add missing sock updates for SCM_RIGHTS
  pidfd: Add missing sock updates for pidfd_getfd()
  net/scm: Regularize compat handling of scm_detach_fds()
  fs: Move __scm_install_fd() to __receive_fd()
  fs: Add receive_fd() wrapper for __receive_fd()
  pidfd: Replace open-coded receive_fd()
  fs: Expand __receive_fd() to accept existing fd

Sargun Dhillon (2):
  seccomp: Introduce addfd ioctl to seccomp user notifier
  selftests/seccomp: Test SECCOMP_IOCTL_NOTIF_ADDFD

 fs/file.c                                     |  57 +++++
 include/linux/file.h                          |  19 ++
 include/linux/seccomp.h                       |   4 +
 include/net/sock.h                            |   4 +
 include/uapi/linux/seccomp.h                  |  22 ++
 kernel/pid.c                                  |  14 +-
 kernel/seccomp.c                              | 173 ++++++++++++-
 net/compat.c                                  |  55 ++---
 net/core/scm.c                                |  50 +---
 net/core/sock.c                               |  21 ++
 tools/testing/selftests/seccomp/seccomp_bpf.c | 229 ++++++++++++++++++
 11 files changed, 566 insertions(+), 82 deletions(-)
  

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