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Mike Rapoport 3c1c24d91f userfaultfd: require CAP_SYS_PTRACE for UFFD_FEATURE_EVENT_FORK 
A while ago Andy noticed
(http://lkml.kernel.org/r/CALCETrWY+5ynDct7eU_nDUqx=okQvjm=Y5wJvA4ahBja=CQXGw@mail.gmail.com)
that UFFD_FEATURE_EVENT_FORK used by an unprivileged user may have
security implications.

As the first step of the solution the following patch limits the availably
of UFFD_FEATURE_EVENT_FORK only for those having CAP_SYS_PTRACE.

The usage of CAP_SYS_PTRACE ensures compatibility with CRIU.

Yet, if there are other users of non-cooperative userfaultfd that run
without CAP_SYS_PTRACE, they would be broken :(

Current implementation of UFFD_FEATURE_EVENT_FORK modifies the file
descriptor table from the read() implementation of uffd, which may have
security implications for unprivileged use of the userfaultfd.

Limit availability of UFFD_FEATURE_EVENT_FORK only for callers that have
CAP_SYS_PTRACE.

Link: http://lkml.kernel.org/r/1572967777-8812-2-git-send-email-rppt@linux.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Daniel Colascione <dancol@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Nick Kralevich <nnk@google.com>
Cc: Nosh Minwalla <nosh@google.com>
Cc: Pavel Emelyanov <ovzxemul@gmail.com>
Cc: Tim Murray <timmurray@google.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-12-01 12:59:10 -08:00
arch powerpc/mm: remove pmd_huge/pud_huge stubs and include hugetlb.h 2019-12-01 12:59:08 -08:00
block
certs
crypto
Documentation kasan: support backing vmalloc space with real shadow memory 2019-12-01 12:59:05 -08:00
drivers drivers/base/memory.c: drop the mem_sysfs_mutex 2019-12-01 12:59:04 -08:00
fs userfaultfd: require CAP_SYS_PTRACE for UFFD_FEATURE_EVENT_FORK 2019-12-01 12:59:10 -08:00
include hugetlb: remove unused hstate in hugetlb_fault_mutex_hash() 2019-12-01 12:59:08 -08:00
init
ipc
kernel kernel: sysctl: make drop_caches write-only 2019-12-01 12:59:07 -08:00
lib kasan: add test for vmalloc 2019-12-01 12:59:05 -08:00
LICENSES
mm userfaultfd: wrap the common dst_vma check into an inlined function 2019-12-01 12:59:10 -08:00
net for-5.5/io_uring-post-20191128 2019-11-28 10:43:39 -08:00
samples
scripts scripts/spelling.txt: add more spellings to spelling.txt 2019-12-01 06:29:17 -08:00
security drm main pull for 5.5-rc1 2019-11-27 17:45:48 -08:00
sound
tools selftests: vm: add fragment CONFIG_TEST_VMALLOC 2019-12-01 12:59:05 -08:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS \n 2019-11-30 11:34:33 -08:00
Makefile
README

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.