[PATCH 0/2] Control over userfaultfd kernel-fault handling

[Daniel Colascione]

This small patch series adds a new flag to userfaultfd(2) that allows
callers to give up the ability to handle user-mode faults with the
resulting UFFD file object. In then add a new sysctl to require
unprivileged callers to use this new flag.

The purpose of this new interface is to decrease the change of an
unprivileged userfaultfd user taking advantage of userfaultfd to
enhance security vulnerabilities by lengthening the race window in
kernel code.

This patch series is split from [1].

[1] https://lore.kernel.org/lkml/20200211225547.235083-1-dancol@xxxxxxxxxx/

Daniel Colascione (2):
  Add UFFD_USER_MODE_ONLY
  Add a new sysctl knob: unprivileged_userfaultfd_user_mode_only

 Documentation/admin-guide/sysctl/vm.rst | 13 +++++++++++++
 fs/userfaultfd.c                        | 18 ++++++++++++++++--
 include/linux/userfaultfd_k.h           |  1 +
 include/uapi/linux/userfaultfd.h        |  9 +++++++++
 kernel/sysctl.c                         |  9 +++++++++
 5 files changed, 48 insertions(+), 2 deletions(-)

-- 
2.26.2.303.gf8c07b1a785-goog