Use new return type vm_fault_t for fault handler in struct
vm_operations_struct. For now, this is just documenting that the
function returns a VM_FAULT value rather than an errno. Once all
instances are converted, vm_fault_t will become a distinct type.
See commit 1c8f422059 ("mm: change return type to vm_fault_t")
Link: http://lkml.kernel.org/r/20180512063745.GA26866@jordon-HP-15-Notebook-PC
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joe Perches <joe@perches.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
including:
- Extensive RST conversions and organizational work in the
memory-management docs thanks to Mike Rapoport.
- An update of Documentation/features from Andrea Parri and a script to
keep it updated.
- Various LICENSES updates from Thomas, along with a script to check SPDX
tags.
- Work to fix dangling references to documentation files; this involved a
fair number of one-liner comment changes outside of Documentation/
...and the usual list of documentation improvements, typo fixes, etc.
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Merge tag 'docs-4.18' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet:
"There's been a fair amount of work in the docs tree this time around,
including:
- Extensive RST conversions and organizational work in the
memory-management docs thanks to Mike Rapoport.
- An update of Documentation/features from Andrea Parri and a script
to keep it updated.
- Various LICENSES updates from Thomas, along with a script to check
SPDX tags.
- Work to fix dangling references to documentation files; this
involved a fair number of one-liner comment changes outside of
Documentation/
... and the usual list of documentation improvements, typo fixes, etc"
* tag 'docs-4.18' of git://git.lwn.net/linux: (103 commits)
Documentation: document hung_task_panic kernel parameter
docs/admin-guide/mm: add high level concepts overview
docs/vm: move ksm and transhuge from "user" to "internals" section.
docs: Use the kerneldoc comments for memalloc_no*()
doc: document scope NOFS, NOIO APIs
docs: update kernel versions and dates in tables
docs/vm: transhuge: split userspace bits to admin-guide/mm/transhuge
docs/vm: transhuge: minor updates
docs/vm: transhuge: change sections order
Documentation: arm: clean up Marvell Berlin family info
Documentation: gpio: driver: Fix a typo and some odd grammar
docs: ranoops.rst: fix location of ramoops.txt
scripts/documentation-file-ref-check: rewrite it in perl with auto-fix mode
docs: uio-howto.rst: use a code block to solve a warning
mm, THP, doc: Add document for thp_swpout/thp_swpout_fallback
w1: w1_io.c: fix a kernel-doc warning
Documentation/process/posting: wrap text at 80 cols
docs: admin-guide: add cgroup-v2 documentation
Revert "Documentation/features/vm: Remove arch support status file for 'pte_special'"
Documentation: refcount-vs-atomic: Update reference to LKMM doc.
...
Commit be83bbf806 ("mmap: introduce sane default mmap limits") was
introduced to catch problems in various ad-hoc character device drivers
doing mmap and getting the size limits wrong. In the process, it used
"known good" limits for the normal cases of mapping regular files and
block device drivers.
It turns out that the "s_maxbytes" limit was less "known good" than I
thought. In particular, /proc doesn't set it, but exposes one regular
file to mmap: /proc/vmcore. As a result, that file got limited to the
default MAX_INT s_maxbytes value.
This went unnoticed for a while, because apparently the only thing that
needs it is the s390 kernel zfcpdump, but there might be other tools
that use this too.
Vasily suggested just changing s_maxbytes for all of /proc, which isn't
wrong, but makes me nervous at this stage. So instead, just make the
new mmap limit always be MAX_LFS_FILESIZE for regular files, which won't
affect anything else. It wasn't the regular file case I was worried
about.
I'd really prefer for maxsize to have been per-inode, but that is not
how things are today.
Fixes: be83bbf806 ("mmap: introduce sane default mmap limits")
Reported-by: Vasily Gorbik <gor@linux.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge misc fixes from Andrew Morton:
"13 fixes"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
rbtree: include rcu.h
scripts/faddr2line: fix error when addr2line output contains discriminator
ocfs2: take inode cluster lock before moving reflinked inode from orphan dir
mm, oom: fix concurrent munlock and oom reaper unmap, v3
mm: migrate: fix double call of radix_tree_replace_slot()
proc/kcore: don't bounds check against address 0
mm: don't show nr_indirectly_reclaimable in /proc/vmstat
mm: sections are not offlined during memory hotremove
z3fold: fix reclaim lock-ups
init: fix false positives in W+X checking
lib/find_bit_benchmark.c: avoid soft lockup in test_find_first_bit()
KASAN: prohibit KASAN+STRUCTLEAK combination
MAINTAINERS: update Shuah's email address
Since exit_mmap() is done without the protection of mm->mmap_sem, it is
possible for the oom reaper to concurrently operate on an mm until
MMF_OOM_SKIP is set.
This allows munlock_vma_pages_all() to concurrently run while the oom
reaper is operating on a vma. Since munlock_vma_pages_range() depends
on clearing VM_LOCKED from vm_flags before actually doing the munlock to
determine if any other vmas are locking the same memory, the check for
VM_LOCKED in the oom reaper is racy.
This is especially noticeable on architectures such as powerpc where
clearing a huge pmd requires serialize_against_pte_lookup(). If the pmd
is zapped by the oom reaper during follow_page_mask() after the check
for pmd_none() is bypassed, this ends up deferencing a NULL ptl or a
kernel oops.
Fix this by manually freeing all possible memory from the mm before
doing the munlock and then setting MMF_OOM_SKIP. The oom reaper can not
run on the mm anymore so the munlock is safe to do in exit_mmap(). It
also matches the logic that the oom reaper currently uses for
determining when to set MMF_OOM_SKIP itself, so there's no new risk of
excessive oom killing.
This issue fixes CVE-2018-1000200.
Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1804241526320.238665@chino.kir.corp.google.com
Fixes: 2129258024 ("mm: oom: let oom_reap_task and exit_mmap run concurrently")
Signed-off-by: David Rientjes <rientjes@google.com>
Suggested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org> [4.14+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The internal VM "mmap()" interfaces are based on the mmap target doing
everything using page indexes rather than byte offsets, because
traditionally (ie 32-bit) we had the situation that the byte offset
didn't fit in a register. So while the mmap virtual address was limited
by the word size of the architecture, the backing store was not.
So we're basically passing "pgoff" around as a page index, in order to
be able to describe backing store locations that are much bigger than
the word size (think files larger than 4GB etc).
But while this all makes a ton of sense conceptually, we've been dogged
by various drivers that don't really understand this, and internally
work with byte offsets, and then try to work with the page index by
turning it into a byte offset with "pgoff << PAGE_SHIFT".
Which obviously can overflow.
Adding the size of the mapping to it to get the byte offset of the end
of the backing store just exacerbates the problem, and if you then use
this overflow-prone value to check various limits of your device driver
mmap capability, you're just setting yourself up for problems.
The correct thing for drivers to do is to do their limit math in page
indices, the way the interface is designed. Because the generic mmap
code _does_ test that the index doesn't overflow, since that's what the
mmap code really cares about.
HOWEVER.
Finding and fixing various random drivers is a sisyphean task, so let's
just see if we can just make the core mmap() code do the limiting for
us. Realistically, the only "big" backing stores we need to care about
are regular files and block devices, both of which are known to do this
properly, and which have nice well-defined limits for how much data they
can access.
So let's special-case just those two known cases, and then limit other
random mmap users to a backing store that still fits in "unsigned long".
Realistically, that's not much of a limit at all on 64-bit, and on
32-bit architectures the only worry might be the GPU drivers, which can
have big physical address spaces.
To make it possible for drivers like that to say that they are 64-bit
clean, this patch does repurpose the "FMODE_UNSIGNED_OFFSET" bit in the
file flags to allow drivers to mark their file descriptors as safe in
the full 64-bit mmap address space.
[ The timing for doing this is less than optimal, and this should really
go in a merge window. But realistically, this needs wide testing more
than it needs anything else, and being main-line is the only way to do
that.
So the earlier the better, even if it's outside the proper development
cycle - Linus ]
Cc: Kees Cook <keescook@chromium.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Dave Airlie <airlied@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
commit ce9962bf7e22bb3891655c349faff618922d4a73
0day reported warnings at boot on 32-bit systems without NX support:
attempted to set unsupported pgprot: 8000000000000025 bits: 8000000000000000 supported: 7fffffffffffffff
WARNING: CPU: 0 PID: 1 at
arch/x86/include/asm/pgtable.h:540 handle_mm_fault+0xfc1/0xfe0:
check_pgprot at arch/x86/include/asm/pgtable.h:535
(inlined by) pfn_pte at arch/x86/include/asm/pgtable.h:549
(inlined by) do_anonymous_page at mm/memory.c:3169
(inlined by) handle_pte_fault at mm/memory.c:3961
(inlined by) __handle_mm_fault at mm/memory.c:4087
(inlined by) handle_mm_fault at mm/memory.c:4124
The problem is that due to the recent commit which removed auto-massaging
of page protections, filtering page permissions at PTE creation time is not
longer done, so vma->vm_page_prot is passed unfiltered to PTE creation.
Filter the page protections before they are installed in vma->vm_page_prot.
Fixes: fb43d6cb91 ("x86/mm: Do not auto-massage page protections")
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Link: https://lkml.kernel.org/r/20180420222028.99D72858@viggo.jf.intel.com
Mike Rapoport says:
These patches convert files in Documentation/vm to ReST format, add an
initial index and link it to the top level documentation.
There are no contents changes in the documentation, except few spelling
fixes. The relatively large diffstat stems from the indentation and
paragraph wrapping changes.
I've tried to keep the formatting as consistent as possible, but I could
miss some places that needed markup and add some markup where it was not
necessary.
[jc: significant conflicts in vm/hmm.rst]
Patch series "mm: introduce MAP_FIXED_NOREPLACE", v2.
This has started as a follow up discussion [3][4] resulting in the
runtime failure caused by hardening patch [5] which removes MAP_FIXED
from the elf loader because MAP_FIXED is inherently dangerous as it
might silently clobber an existing underlying mapping (e.g. stack).
The reason for the failure is that some architectures enforce an
alignment for the given address hint without MAP_FIXED used (e.g. for
shared or file backed mappings).
One way around this would be excluding those archs which do alignment
tricks from the hardening [6]. The patch is really trivial but it has
been objected, rightfully so, that this screams for a more generic
solution. We basically want a non-destructive MAP_FIXED.
The first patch introduced MAP_FIXED_NOREPLACE which enforces the given
address but unlike MAP_FIXED it fails with EEXIST if the given range
conflicts with an existing one. The flag is introduced as a completely
new one rather than a MAP_FIXED extension because of the backward
compatibility. We really want a never-clobber semantic even on older
kernels which do not recognize the flag. Unfortunately mmap sucks
wrt flags evaluation because we do not EINVAL on unknown flags. On
those kernels we would simply use the traditional hint based semantic so
the caller can still get a different address (which sucks) but at least
not silently corrupt an existing mapping. I do not see a good way
around that. Except we won't export expose the new semantic to the
userspace at all.
It seems there are users who would like to have something like that.
Jemalloc has been mentioned by Michael Ellerman [7]
Florian Weimer has mentioned the following:
: glibc ld.so currently maps DSOs without hints. This means that the kernel
: will map right next to each other, and the offsets between them a completely
: predictable. We would like to change that and supply a random address in a
: window of the address space. If there is a conflict, we do not want the
: kernel to pick a non-random address. Instead, we would try again with a
: random address.
John Hubbard has mentioned CUDA example
: a) Searches /proc/<pid>/maps for a "suitable" region of available
: VA space. "Suitable" generally means it has to have a base address
: within a certain limited range (a particular device model might
: have odd limitations, for example), it has to be large enough, and
: alignment has to be large enough (again, various devices may have
: constraints that lead us to do this).
:
: This is of course subject to races with other threads in the process.
:
: Let's say it finds a region starting at va.
:
: b) Next it does:
: p = mmap(va, ...)
:
: *without* setting MAP_FIXED, of course (so va is just a hint), to
: attempt to safely reserve that region. If p != va, then in most cases,
: this is a failure (almost certainly due to another thread getting a
: mapping from that region before we did), and so this layer now has to
: call munmap(), before returning a "failure: retry" to upper layers.
:
: IMPROVEMENT: --> if instead, we could call this:
:
: p = mmap(va, ... MAP_FIXED_NOREPLACE ...)
:
: , then we could skip the munmap() call upon failure. This
: is a small thing, but it is useful here. (Thanks to Piotr
: Jaroszynski and Mark Hairgrove for helping me get that detail
: exactly right, btw.)
:
: c) After that, CUDA suballocates from p, via:
:
: q = mmap(sub_region_start, ... MAP_FIXED ...)
:
: Interestingly enough, "freeing" is also done via MAP_FIXED, and
: setting PROT_NONE to the subregion. Anyway, I just included (c) for
: general interest.
Atomic address range probing in the multithreaded programs in general
sounds like an interesting thing to me.
The second patch simply replaces MAP_FIXED use in elf loader by
MAP_FIXED_NOREPLACE. I believe other places which rely on MAP_FIXED
should follow. Actually real MAP_FIXED usages should be docummented
properly and they should be more of an exception.
[1] http://lkml.kernel.org/r/20171116101900.13621-1-mhocko@kernel.org
[2] http://lkml.kernel.org/r/20171129144219.22867-1-mhocko@kernel.org
[3] http://lkml.kernel.org/r/20171107162217.382cd754@canb.auug.org.au
[4] http://lkml.kernel.org/r/1510048229.12079.7.camel@abdul.in.ibm.com
[5] http://lkml.kernel.org/r/20171023082608.6167-1-mhocko@kernel.org
[6] http://lkml.kernel.org/r/20171113094203.aofz2e7kueitk55y@dhcp22.suse.cz
[7] http://lkml.kernel.org/r/87efp1w7vy.fsf@concordia.ellerman.id.au
This patch (of 2):
MAP_FIXED is used quite often to enforce mapping at the particular range.
The main problem of this flag is, however, that it is inherently dangerous
because it unmaps existing mappings covered by the requested range. This
can cause silent memory corruptions. Some of them even with serious
security implications. While the current semantic might be really
desiderable in many cases there are others which would want to enforce the
given range but rather see a failure than a silent memory corruption on a
clashing range. Please note that there is no guarantee that a given range
is obeyed by the mmap even when it is free - e.g. arch specific code is
allowed to apply an alignment.
Introduce a new MAP_FIXED_NOREPLACE flag for mmap to achieve this
behavior. It has the same semantic as MAP_FIXED wrt. the given address
request with a single exception that it fails with EEXIST if the requested
address is already covered by an existing mapping. We still do rely on
get_unmaped_area to handle all the arch specific MAP_FIXED treatment and
check for a conflicting vma after it returns.
The flag is introduced as a completely new one rather than a MAP_FIXED
extension because of the backward compatibility. We really want a
never-clobber semantic even on older kernels which do not recognize the
flag. Unfortunately mmap sucks wrt. flags evaluation because we do not
EINVAL on unknown flags. On those kernels we would simply use the
traditional hint based semantic so the caller can still get a different
address (which sucks) but at least not silently corrupt an existing
mapping. I do not see a good way around that.
[mpe@ellerman.id.au: fix whitespace]
[fail on clashing range with EEXIST as per Florian Weimer]
[set MAP_FIXED before round_hint_to_min as per Khalid Aziz]
Link: http://lkml.kernel.org/r/20171213092550.2774-2-mhocko@kernel.org
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Russell King - ARM Linux <linux@armlinux.org.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Abdul Haleem <abdhalee@linux.vnet.ibm.com>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Jason Evans <jasone@google.com>
Cc: David Goldblatt <davidtgoldblatt@gmail.com>
Cc: Edward Tomasz Napierała <trasz@FreeBSD.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The documentation for ignore_rlimit_data says that it will print a
warning at first misuse. Yet it doesn't seem to do that.
Fix the code to print the warning even when we allow the process to
continue.
Link: http://lkml.kernel.org/r/1517935505-9321-1-git-send-email-dwmw@amazon.co.uk
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Acked-by: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Using this helper allows us to avoid the in-kernel calls to the
sys_mmap_pgoff() syscall. The ksys_ prefix denotes that this function is
meant as a drop-in replacement for the syscall. In particular, it uses the
same calling convention as sys_mmap_pgoff().
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
David Rientjes has reported the following memory corruption while the
oom reaper tries to unmap the victims address space
BUG: Bad page map in process oom_reaper pte:6353826300000000 pmd:00000000
addr:00007f50cab1d000 vm_flags:08100073 anon_vma:ffff9eea335603f0 mapping: (null) index:7f50cab1d
file: (null) fault: (null) mmap: (null) readpage: (null)
CPU: 2 PID: 1001 Comm: oom_reaper
Call Trace:
unmap_page_range+0x1068/0x1130
__oom_reap_task_mm+0xd5/0x16b
oom_reaper+0xff/0x14c
kthread+0xc1/0xe0
Tetsuo Handa has noticed that the synchronization inside exit_mmap is
insufficient. We only synchronize with the oom reaper if
tsk_is_oom_victim which is not true if the final __mmput is called from
a different context than the oom victim exit path. This can trivially
happen from context of any task which has grabbed mm reference (e.g. to
read /proc/<pid>/ file which requires mm etc.).
The race would look like this
oom_reaper oom_victim task
mmget_not_zero
do_exit
mmput
__oom_reap_task_mm mmput
__mmput
exit_mmap
remove_vma
unmap_page_range
Fix this issue by providing a new mm_is_oom_victim() helper which
operates on the mm struct rather than a task. Any context which
operates on a remote mm struct should use this helper in place of
tsk_is_oom_victim. The flag is set in mark_oom_victim and never cleared
so it is stable in the exit_mmap path.
Debugged by Tetsuo Handa.
Link: http://lkml.kernel.org/r/20171210095130.17110-1-mhocko@kernel.org
Fixes: 2129258024 ("mm: oom: let oom_reap_task and exit_mmap run concurrently")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: David Rientjes <rientjes@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Andrea Argangeli <andrea@kernel.org>
Cc: <stable@vger.kernel.org> [4.14]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "device-dax: fix unaligned munmap handling"
When device-dax is operating in huge-page mode we want it to behave like
hugetlbfs and fail attempts to split vmas into unaligned ranges. It
would be messy to teach the munmap path about device-dax alignment
constraints in the same (hstate) way that hugetlbfs communicates this
constraint. Instead, these patches introduce a new ->split() vm
operation.
This patch (of 2):
The device-dax interface has similar constraints as hugetlbfs in that it
requires the munmap path to unmap in huge page aligned units. Rather
than add more custom vma handling code in __split_vma() introduce a new
vm operation to perform this vma specific check.
Link: http://lkml.kernel.org/r/151130418135.4029.6783191281930729710.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: dee4107924 ("/dev/dax, core: file operations and dax-mmap")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The mmap(2) syscall suffers from the ABI anti-pattern of not validating
unknown flags. However, proposals like MAP_SYNC need a mechanism to
define new behavior that is known to fail on older kernels without the
support. Define a new MAP_SHARED_VALIDATE flag pattern that is
guaranteed to fail on all legacy mmap implementations.
It is worth noting that the original proposal was for a standalone
MAP_VALIDATE flag. However, when that could not be supported by all
archs Linus observed:
I see why you *think* you want a bitmap. You think you want
a bitmap because you want to make MAP_VALIDATE be part of MAP_SYNC
etc, so that people can do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED
| MAP_SYNC, fd, 0);
and "know" that MAP_SYNC actually takes.
And I'm saying that whole wish is bogus. You're fundamentally
depending on special semantics, just make it explicit. It's already
not portable, so don't try to make it so.
Rename that MAP_VALIDATE as MAP_SHARED_VALIDATE, make it have a value
of 0x3, and make people do
ret = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED_VALIDATE
| MAP_SYNC, fd, 0);
and then the kernel side is easier too (none of that random garbage
playing games with looking at the "MAP_VALIDATE bit", but just another
case statement in that map type thing.
Boom. Done.
Similar to ->fallocate() we also want the ability to validate the
support for new flags on a per ->mmap() 'struct file_operations'
instance basis. Towards that end arrange for flags to be generically
validated against a mmap_supported_flags exported by 'struct
file_operations'. By default all existing flags are implicitly
supported, but new flags require MAP_SHARED_VALIDATE and
per-instance-opt-in.
Cc: Jan Kara <jack@suse.cz>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Suggested-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Allow interval trees to quickly check for overlaps to avoid unnecesary
tree lookups in interval_tree_iter_first().
As of this patch, all interval tree flavors will require using a
'rb_root_cached' such that we can have the leftmost node easily
available. While most users will make use of this feature, those with
special functions (in addition to the generic insert, delete, search
calls) will avoid using the cached option as they can do funky things
with insertions -- for example, vma_interval_tree_insert_after().
[jglisse@redhat.com: fix deadlock from typo vm_lock_anon_vma()]
Link: http://lkml.kernel.org/r/20170808225719.20723-1-jglisse@redhat.com
Link: http://lkml.kernel.org/r/20170719014603.19029-12-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Acked-by: Christian König <christian.koenig@amd.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Doug Ledford <dledford@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Christian Benvenuti <benve@cisco.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is purely required because exit_aio() may block and exit_mmap() may
never start, if the oom_reap_task cannot start running on a mm with
mm_users == 0.
At the same time if the OOM reaper doesn't wait at all for the memory of
the current OOM candidate to be freed by exit_mmap->unmap_vmas, it would
generate a spurious OOM kill.
If it wasn't because of the exit_aio or similar blocking functions in
the last mmput, it would be enough to change the oom_reap_task() in the
case it finds mm_users == 0, to wait for a timeout or to wait for
__mmput to set MMF_OOM_SKIP itself, but it's not just exit_mmap the
problem here so the concurrency of exit_mmap and oom_reap_task is
apparently warranted.
It's a non standard runtime, exit_mmap() runs without mmap_sem, and
oom_reap_task runs with the mmap_sem for reading as usual (kind of
MADV_DONTNEED).
The race between the two is solved with a combination of
tsk_is_oom_victim() (serialized by task_lock) and MMF_OOM_SKIP
(serialized by a dummy down_write/up_write cycle on the same lines of
the ksm_exit method).
If the oom_reap_task() may be running concurrently during exit_mmap,
exit_mmap will wait it to finish in down_write (before taking down mm
structures that would make the oom_reap_task fail with use after free).
If exit_mmap comes first, oom_reap_task() will skip the mm if
MMF_OOM_SKIP is already set and in turn all memory is already freed and
furthermore the mm data structures may already have been taken down by
free_pgtables.
[aarcange@redhat.com: incremental one liner]
Link: http://lkml.kernel.org/r/20170726164319.GC29716@redhat.com
[rientjes@google.com: remove unused mmput_async]
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1708141733130.50317@chino.kir.corp.google.com
[aarcange@redhat.com: microoptimization]
Link: http://lkml.kernel.org/r/20170817171240.GB5066@redhat.com
Link: http://lkml.kernel.org/r/20170726162912.GA29716@redhat.com
Fixes: 26db62f179 ("oom: keep mm of the killed task available")
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: David Rientjes <rientjes@google.com>
Tested-by: David Rientjes <rientjes@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A __split_vma is not a worthy event to report, and it's definitely not a
unmap so it would be incorrect to report unmap for the whole region to
the userfaultfd manager if a __split_vma fails.
So only call userfaultfd_unmap_prep after the __vma_splitting is over
and do_munmap cannot fail anymore.
Also add unlikely because it's better to optimize for the vast majority
of apps that aren't using userfaultfd in a non cooperative way. Ideally
we should also find a way to eliminate the branch entirely if
CONFIG_USERFAULTFD=n, but it would complicate things so stick to
unlikely for now.
Link: http://lkml.kernel.org/r/20170802165145.22628-5-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Alexey Perevalov <a.perevalov@samsung.com>
Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
global_page_state is error prone as a recent bug report pointed out [1].
It only returns proper values for zone based counters as the enum it
gets suggests. We already have global_node_page_state so let's rename
global_page_state to global_zone_page_state to be more explicit here.
All existing users seems to be correct:
$ git grep "global_page_state(NR_" | sed 's@.*(\(NR_[A-Z_]*\)).*@\1@' | sort | uniq -c
2 NR_BOUNCE
2 NR_FREE_CMA_PAGES
11 NR_FREE_PAGES
1 NR_KERNEL_STACK_KB
1 NR_MLOCK
2 NR_PAGETABLE
This patch shouldn't introduce any functional change.
[1] http://lkml.kernel.org/r/201707260628.v6Q6SmaS030814@www262.sakura.ne.jp
Link: http://lkml.kernel.org/r/20170801134256.5400-2-hannes@cmpxchg.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jörn Engel noticed that the expand_upwards() function might not return
-ENOMEM in case the requested address is (unsigned long)-PAGE_SIZE and
if the architecture didn't defined TASK_SIZE as multiple of PAGE_SIZE.
Affected architectures are arm, frv, m68k, blackfin, h8300 and xtensa
which all define TASK_SIZE as 0xffffffff, but since none of those have
an upwards-growing stack we currently have no actual issue.
Nevertheless let's fix this just in case any of the architectures with
an upward-growing stack (currently parisc, metag and partly ia64) define
TASK_SIZE similar.
Link: http://lkml.kernel.org/r/20170702192452.GA11868@p100.box
Fixes: bd726c90b6 ("Allow stack to grow up to address space limit")
Signed-off-by: Helge Deller <deller@gmx.de>
Reported-by: Jörn Engel <joern@purestorage.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use rlimit() helper instead of manually writing whole chain from current
task to rlim_cur.
Link: http://lkml.kernel.org/r/20170705172811.8027-1-k.opasiak@samsung.com
Signed-off-by: Krzysztof Opasiak <k.opasiak@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
expand_stack(vma) fails if address < stack_guard_gap even if there is no
vma->vm_prev. I don't think this makes sense, and we didn't do this
before the recent commit 1be7107fbe ("mm: larger stack guard gap,
between vmas").
We do not need a gap in this case, any address is fine as long as
security_mmap_addr() doesn't object.
This also simplifies the code, we know that address >= prev->vm_end and
thus underflow is not possible.
Link: http://lkml.kernel.org/r/20170628175258.GA24881@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 1be7107fbe ("mm: larger stack guard gap, between vmas") has
introduced a regression in some rust and Java environments which are
trying to implement their own stack guard page. They are punching a new
MAP_FIXED mapping inside the existing stack Vma.
This will confuse expand_{downwards,upwards} into thinking that the
stack expansion would in fact get us too close to an existing non-stack
vma which is a correct behavior wrt safety. It is a real regression on
the other hand.
Let's work around the problem by considering PROT_NONE mapping as a part
of the stack. This is a gros hack but overflowing to such a mapping
would trap anyway an we only can hope that usespace knows what it is
doing and handle it propely.
Fixes: 1be7107fbe ("mm: larger stack guard gap, between vmas")
Link: http://lkml.kernel.org/r/20170705182849.GA18027@dhcp22.suse.cz
Signed-off-by: Michal Hocko <mhocko@suse.com>
Debugged-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Ben Hutchings <ben@decadent.org.uk>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull ARM updates from Russell King:
- add support for ftrace-with-registers, which is needed for kgraft and
other ftrace tools
- support for mremap() for the sigpage/vDSO so that checkpoint/restore
can work
- add timestamps to each line of the register dump output
- remove the unused KTHREAD_SIZE from nommu
- align the ARM bitops APIs with the generic API (using unsigned long
pointers rather than void pointers)
- make the configuration of userspace Thumb support an expert option so
that we can default it on, and avoid some hard to debug userspace
crashes
* 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
ARM: 8684/1: NOMMU: Remove unused KTHREAD_SIZE definition
ARM: 8683/1: ARM32: Support mremap() for sigpage/vDSO
ARM: 8679/1: bitops: Align prototypes to generic API
ARM: 8678/1: ftrace: Adds support for CONFIG_DYNAMIC_FTRACE_WITH_REGS
ARM: make configuration of userspace Thumb support an expert option
ARM: 8673/1: Fix __show_regs output timestamps
The protection map is only modified by per-arch init code so it can be
protected from writes after the init code runs.
This change was extracted from PaX where it's part of KERNEXEC.
Link: http://lkml.kernel.org/r/20170510174441.26163-1-danielmicay@gmail.com
Signed-off-by: Daniel Micay <danielmicay@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix expand_upwards() on architectures with an upward-growing stack (parisc,
metag and partly IA-64) to allow the stack to reliably grow exactly up to
the address space limit given by TASK_SIZE.
Signed-off-by: Helge Deller <deller@gmx.de>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Trinity gets kernel BUG at mm/mmap.c:1963! in about 3 minutes of
mmap testing. That's the VM_BUG_ON(gap_end < gap_start) at the
end of unmapped_area_topdown(). Linus points out how MAP_FIXED
(which does not have to respect our stack guard gap intentions)
could result in gap_end below gap_start there. Fix that, and
the similar case in its alternative, unmapped_area().
Cc: stable@vger.kernel.org
Fixes: 1be7107fbe ("mm: larger stack guard gap, between vmas")
Reported-by: Dave Jones <davej@codemonkey.org.uk>
Debugged-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
CRIU restores application mappings on the same place where they
were before Checkpoint. That means, that we need to move vDSO
and sigpage during restore on exactly the same place where
they were before C/R.
Make mremap() code update mm->context.{sigpage,vdso} pointers
during VMA move. Sigpage is used for landing after handling
a signal - if the pointer is not updated during moving, the
application might crash on any signal after mremap().
vDSO pointer on ARM32 is used only for setting auxv at this moment,
update it during mremap() in case of future usage.
Without those updates, current work of CRIU on ARM32 is not reliable.
Historically, we error Checkpointing if we find vDSO page on ARM32
and suggest user to disable CONFIG_VDSO.
But that's not correct - it goes from x86 where signal processing
is ended in vDSO blob. For arm32 it's sigpage, which is not disabled
with `CONFIG_VDSO=n'.
Looks like C/R was working by luck - because userspace on ARM32 at
this moment always sets SA_RESTORER.
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Will Deacon <will.deacon@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Stack guard page is a useful feature to reduce a risk of stack smashing
into a different mapping. We have been using a single page gap which
is sufficient to prevent having stack adjacent to a different mapping.
But this seems to be insufficient in the light of the stack usage in
userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
which is 256kB or stack strings with MAX_ARG_STRLEN.
This will become especially dangerous for suid binaries and the default
no limit for the stack size limit because those applications can be
tricked to consume a large portion of the stack and a single glibc call
could jump over the guard page. These attacks are not theoretical,
unfortunatelly.
Make those attacks less probable by increasing the stack guard gap
to 1MB (on systems with 4k pages; but make it depend on the page size
because systems with larger base pages might cap stack allocations in
the PAGE_SIZE units) which should cover larger alloca() and VLA stack
allocations. It is obviously not a full fix because the problem is
somehow inherent, but it should reduce attack space a lot.
One could argue that the gap size should be configurable from userspace,
but that can be done later when somebody finds that the new 1MB is wrong
for some special case applications. For now, add a kernel command line
option (stack_guard_gap) to specify the stack gap size (in page units).
Implementation wise, first delete all the old code for stack guard page:
because although we could get away with accounting one extra page in a
stack vma, accounting a larger gap can break userspace - case in point,
a program run with "ulimit -S -v 20000" failed when the 1MB gap was
counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
and strict non-overcommit mode.
Instead of keeping gap inside the stack vma, maintain the stack guard
gap as a gap between vmas: using vm_start_gap() in place of vm_start
(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
places which need to respect the gap - mainly arch_get_unmapped_area(),
and and the vma tree's subtree_gap support for that.
Original-patch-by: Oleg Nesterov <oleg@redhat.com>
Original-patch-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 091d0d55b2 ("shm: fix null pointer deref when userspace
specifies invalid hugepage size") had replaced MAP_HUGE_MASK with
SHM_HUGE_MASK. Though both of them contain the same numeric value of
0x3f, MAP_HUGE_MASK flag sounds more appropriate than the other one in
the context. Hence change it back.
Link: http://lkml.kernel.org/r/20170404045635.616-1-khandual@linux.vnet.ibm.com
Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull vfs pile two from Al Viro:
- orangefs fix
- series of fs/namei.c cleanups from me
- VFS stuff coming from overlayfs tree
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
orangefs: Use RCU for destroy_inode
vfs: use helper for calling f_op->fsync()
mm: use helper for calling f_op->mmap()
vfs: use helpers for calling f_op->{read,write}_iter()
vfs: pass type instead of fn to do_{loop,iter}_readv_writev()
vfs: extract common parts of {compat_,}do_readv_writev()
vfs: wrap write f_ops with file_{start,end}_write()
vfs: deny copy_file_range() for non regular files
vfs: deny fallocate() on directory
vfs: create vfs helper vfs_tmpfile()
namei.c: split unlazy_walk()
namei.c: fold the check for DCACHE_OP_REVALIDATE into d_revalidate()
lookup_fast(): clean up the logics around the fallback to non-rcu mode
namei: fold unlazy_link() into its sole caller
If madvise(2) advice will result in the underlying vma being split and
the number of areas mapped by the process will exceed
/proc/sys/vm/max_map_count as a result, return ENOMEM instead of EAGAIN.
EAGAIN is returned by madvise(2) when a kernel resource, such as slab,
is temporarily unavailable. It indicates that userspace should retry
the advice in the near future. This is important for advice such as
MADV_DONTNEED which is often used by malloc implementations to free
memory back to the system: we really do want to free memory back when
madvise(2) returns EAGAIN because slab allocations (for vmas, anon_vmas,
or mempolicies) cannot be allocated.
Encountering /proc/sys/vm/max_map_count is not a temporary failure,
however, so return ENOMEM to indicate this is a more serious issue. A
followup patch to the man page will specify this behavior.
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1701241431120.42507@chino.kir.corp.google.com
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When a non-cooperative userfaultfd monitor copies pages in the
background, it may encounter regions that were already unmapped.
Addition of UFFD_EVENT_UNMAP allows the uffd monitor to track precisely
changes in the virtual memory layout.
Since there might be different uffd contexts for the affected VMAs, we
first should create a temporary representation for the unmap event for
each uffd context and then notify them one by one to the appropriate
userfault file descriptors.
The event notification occurs after the mmap_sem has been released.
[arnd@arndb.de: fix nommu build]
Link: http://lkml.kernel.org/r/20170203165141.3665284-1-arnd@arndb.de
[mhocko@suse.com: fix nommu build]
Link: http://lkml.kernel.org/r/20170202091503.GA22823@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/1485542673-24387-3-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "userfaultfd: non-cooperative: better tracking for mapping
changes", v2.
These patches try to address issues I've encountered during integration
of userfaultfd with CRIU.
Previously added userfaultfd events for fork(), madvise() and mremap()
unfortunately do not cover all possible changes to a process virtual
memory layout required for uffd monitor.
When one or more VMAs is removed from the process mm, the external uffd
monitor has no way to detect those changes and will attempt to fill the
removed regions with userfaultfd_copy.
Another problematic event is the exit() of the process. Here again, the
external uffd monitor will try to use userfaultfd_copy, although mm
owning the memory has already gone.
The first patch in the series is a minor cleanup and it's not strictly
related to the rest of the series.
The patches 2 and 3 below add UFFD_EVENT_UNMAP and UFFD_EVENT_EXIT to
allow the uffd monitor track changes in the memory layout of a process.
The patches 4 and 5 amend error codes returned by userfaultfd_copy to
make the uffd monitor able to cope with races that might occur between
delivery of unmap and exit events and outstanding userfaultfd_copy's.
This patch (of 5):
Commit dc0ef0df7b ("mm: make mmap_sem for write waits killable for mm
syscalls") replaced call to vm_munmap in munmap syscall with open coded
version to allow different waits on mmap_sem in munmap syscall and
vm_munmap.
Now both functions use down_write_killable, so we can restore the call
to vm_munmap from the munmap system call.
Link: http://lkml.kernel.org/r/1485542673-24387-2-git-send-email-rppt@linux.vnet.ibm.com
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mmap_init() is no longer associated with VMA slab. So fix it.
Link: http://lkml.kernel.org/r/1485182601-9294-1-git-send-email-iamyooon@gmail.com
Signed-off-by: seokhoon.yoon <iamyooon@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
->fault(), ->page_mkwrite(), and ->pfn_mkwrite() calls do not need to
take a vma and vmf parameter when the vma already resides in vmf.
Remove the vma parameter to simplify things.
[arnd@arndb.de: fix ARM build]
Link: http://lkml.kernel.org/r/20170125223558.1451224-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/148521301778.19116.10840599906674778980.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Darrick J. Wong <darrick.wong@oracle.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On 32-bit powerpc the ELF PLT sections of binaries (built with
--bss-plt, or with a toolchain which defaults to it) look like this:
[17] .sbss NOBITS 0002aff8 01aff8 000014 00 WA 0 0 4
[18] .plt NOBITS 0002b00c 01aff8 000084 00 WAX 0 0 4
[19] .bss NOBITS 0002b090 01aff8 0000a4 00 WA 0 0 4
Which results in an ELF load header:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x019c70 0x00029c70 0x00029c70 0x01388 0x014c4 RWE 0x10000
This is all correct, the load region containing the PLT is marked as
executable. Note that the PLT starts at 0002b00c but the file mapping
ends at 0002aff8, so the PLT falls in the 0 fill section described by
the load header, and after a page boundary.
Unfortunately the generic ELF loader ignores the X bit in the load
headers when it creates the 0 filled non-file backed mappings. It
assumes all of these mappings are RW BSS sections, which is not the case
for PPC.
gcc/ld has an option (--secure-plt) to not do this, this is said to
incur a small performance penalty.
Currently, to support 32-bit binaries with PLT in BSS kernel maps
*entire brk area* with executable rights for all binaries, even
--secure-plt ones.
Stop doing that.
Teach the ELF loader to check the X bit in the relevant load header and
create 0 filled anonymous mappings that are executable if the load
header requests that.
Test program showing the difference in /proc/$PID/maps:
int main() {
char buf[16*1024];
char *p = malloc(123); /* make "[heap]" mapping appear */
int fd = open("/proc/self/maps", O_RDONLY);
int len = read(fd, buf, sizeof(buf));
write(1, buf, len);
printf("%p\n", p);
return 0;
}
Compiled using: gcc -mbss-plt -m32 -Os test.c -otest
Unpatched ppc64 kernel:
00100000-00120000 r-xp 00000000 00:00 0 [vdso]
0fe10000-0ffd0000 r-xp 00000000 fd:00 67898094 /usr/lib/libc-2.17.so
0ffd0000-0ffe0000 r--p 001b0000 fd:00 67898094 /usr/lib/libc-2.17.so
0ffe0000-0fff0000 rw-p 001c0000 fd:00 67898094 /usr/lib/libc-2.17.so
10000000-10010000 r-xp 00000000 fd:00 100674505 /home/user/test
10010000-10020000 r--p 00000000 fd:00 100674505 /home/user/test
10020000-10030000 rw-p 00010000 fd:00 100674505 /home/user/test
10690000-106c0000 rwxp 00000000 00:00 0 [heap]
f7f70000-f7fa0000 r-xp 00000000 fd:00 67898089 /usr/lib/ld-2.17.so
f7fa0000-f7fb0000 r--p 00020000 fd:00 67898089 /usr/lib/ld-2.17.so
f7fb0000-f7fc0000 rw-p 00030000 fd:00 67898089 /usr/lib/ld-2.17.so
ffa90000-ffac0000 rw-p 00000000 00:00 0 [stack]
0x10690008
Patched ppc64 kernel:
00100000-00120000 r-xp 00000000 00:00 0 [vdso]
0fe10000-0ffd0000 r-xp 00000000 fd:00 67898094 /usr/lib/libc-2.17.so
0ffd0000-0ffe0000 r--p 001b0000 fd:00 67898094 /usr/lib/libc-2.17.so
0ffe0000-0fff0000 rw-p 001c0000 fd:00 67898094 /usr/lib/libc-2.17.so
10000000-10010000 r-xp 00000000 fd:00 100674505 /home/user/test
10010000-10020000 r--p 00000000 fd:00 100674505 /home/user/test
10020000-10030000 rw-p 00010000 fd:00 100674505 /home/user/test
10180000-101b0000 rw-p 00000000 00:00 0 [heap]
^^^^ this has changed
f7c60000-f7c90000 r-xp 00000000 fd:00 67898089 /usr/lib/ld-2.17.so
f7c90000-f7ca0000 r--p 00020000 fd:00 67898089 /usr/lib/ld-2.17.so
f7ca0000-f7cb0000 rw-p 00030000 fd:00 67898089 /usr/lib/ld-2.17.so
ff860000-ff890000 rw-p 00000000 00:00 0 [stack]
0x10180008
The patch was originally posted in 2012 by Jason Gunthorpe
and apparently ignored:
https://lkml.org/lkml/2012/9/30/138
Lightly run-tested.
Link: http://lkml.kernel.org/r/20161215131950.23054-1-dvlasenk@redhat.com
Signed-off-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This was entirely automated, using the script by Al:
PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>'
sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \
$(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h)
to do the replacement at the end of the merge window.
Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The old code was always doing:
vma->vm_end = next->vm_end
vma_rb_erase(next) // in __vma_unlink
vma->vm_next = next->vm_next // in __vma_unlink
next = vma->vm_next
vma_gap_update(next)
The new code still does the above for remove_next == 1 and 2, but for
remove_next == 3 it has been changed and it does:
next->vm_start = vma->vm_start
vma_rb_erase(vma) // in __vma_unlink
vma_gap_update(next)
In the latter case, while unlinking "vma", validate_mm_rb() is told to
ignore "vma" that is being removed, but next->vm_start was reduced
instead. So for the new case, to avoid the false positive from
validate_mm_rb, it should be "next" that is ignored when "vma" is
being unlinked.
"vma" and "next" in the above comment, considered pre-swap().
Link: http://lkml.kernel.org/r/1474492522-2261-4-git-send-email-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Tested-by: Shaun Tancheff <shaun.tancheff@seagate.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Jan Vorlicek <janvorli@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The cases are three not two.
Link: http://lkml.kernel.org/r/1474492522-2261-3-git-send-email-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Jan Vorlicek <janvorli@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If next would be NULL we couldn't reach such code path.
Link: http://lkml.kernel.org/r/1474309513-20313-2-git-send-email-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Jan Vorlicek <janvorli@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The rmap_walk can access vm_page_prot (and potentially vm_flags in the
pte/pmd manipulations). So it's not safe to wait the caller to update
the vm_page_prot/vm_flags after vma_merge returned potentially removing
the "next" vma and extending the "current" vma over the
next->vm_start,vm_end range, but still with the "current" vma
vm_page_prot, after releasing the rmap locks.
The vm_page_prot/vm_flags must be transferred from the "next" vma to the
current vma while vma_merge still holds the rmap locks.
The side effect of this race condition is pte corruption during migrate
as remove_migration_ptes when run on a address of the "next" vma that
got removed, used the vm_page_prot of the current vma.
migrate mprotect
------------ -------------
migrating in "next" vma
vma_merge() # removes "next" vma and
# extends "current" vma
# current vma is not with
# vm_page_prot updated
remove_migration_ptes
read vm_page_prot of current "vma"
establish pte with wrong permissions
vm_set_page_prot(vma) # too late!
change_protection in the old vma range
only, next range is not updated
This caused segmentation faults and potentially memory corruption in
heavy mprotect loads with some light page migration caused by compaction
in the background.
Hugh Dickins pointed out the comment about the Odd case 8 in vma_merge
which confirms the case 8 is only buggy one where the race can trigger,
in all other vma_merge cases the above cannot happen.
This fix removes the oddness factor from case 8 and it converts it from:
AAAA
PPPPNNNNXXXX -> PPPPNNNNNNNN
to:
AAAA
PPPPNNNNXXXX -> PPPPXXXXXXXX
XXXX has the right vma properties for the whole merged vma returned by
vma_adjust, so it solves the problem fully. It has the added benefits
that the callers could stop updating vma properties when vma_merge
succeeds however the callers are not updated by this patch (there are
bits like VM_SOFTDIRTY that still need special care for the whole range,
as the vma merging ignores them, but as long as they're not processed by
rmap walks and instead they're accessed with the mmap_sem at least for
reading, they are fine not to be updated within vma_adjust before
releasing the rmap_locks).
Link: http://lkml.kernel.org/r/1474309513-20313-1-git-send-email-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reported-by: Aditya Mandaleeka <adityam@microsoft.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Jan Vorlicek <janvorli@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm->highest_vm_end doesn't need any update.
After finally removing the oddness from vma_merge case 8 that was
causing:
1) constant risk of trouble whenever anybody would check vma fields
from rmap_walks, like it happened when page migration was
introduced and it read the vma->vm_page_prot from a rmap_walk
2) the callers of vma_merge to re-initialize any value different from
the current vma, instead of vma_merge() more reliably returning a
vma that already matches all fields passed as parameter
.. it is also worth to take the opportunity of cleaning up superfluous
code in vma_adjust(), that if not removed adds up to the hard
readability of the function.
Link: http://lkml.kernel.org/r/1474492522-2261-5-git-send-email-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Jan Vorlicek <janvorli@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vma->vm_page_prot is read lockless from the rmap_walk, it may be updated
concurrently and this prevents the risk of reading intermediate values.
Link: http://lkml.kernel.org/r/1474660305-19222-1-git-send-email-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Jan Vorlicek <janvorli@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull x86 vdso updates from Ingo Molnar:
"The main changes in this cycle centered around adding support for
32-bit compatible C/R of the vDSO on 64-bit kernels, by Dmitry
Safonov"
* 'x86-vdso-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/vdso: Use CONFIG_X86_X32_ABI to enable vdso prctl
x86/vdso: Only define map_vdso_randomized() if CONFIG_X86_64
x86/vdso: Only define prctl_map_vdso() if CONFIG_CHECKPOINT_RESTORE
x86/signal: Add SA_{X32,IA32}_ABI sa_flags
x86/ptrace: Down with test_thread_flag(TIF_IA32)
x86/coredump: Use pr_reg size, rather that TIF_IA32 flag
x86/arch_prctl/vdso: Add ARCH_MAP_VDSO_*
x86/vdso: Replace calculate_addr in map_vdso() with addr
x86/vdso: Unmap vdso blob on vvar mapping failure
The ARMv8 architecture allows execute-only user permissions by clearing
the PTE_UXN and PTE_USER bits. However, the kernel running on a CPU
implementation without User Access Override (ARMv8.2 onwards) can still
access such page, so execute-only page permission does not protect
against read(2)/write(2) etc. accesses. Systems requiring such
protection must enable features like SECCOMP.
This patch changes the arm64 __P100 and __S100 protection_map[] macros
to the new __PAGE_EXECONLY attributes. A side effect is that
pte_user() no longer triggers for __PAGE_EXECONLY since PTE_USER isn't
set. To work around this, the check is done on the PTE_NG bit via the
pte_ng() macro. VM_READ is also checked now for page faults.
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
The vm_brk() alignment calculations should refuse to overflow. The ELF
loader depending on this, but it has been fixed now. No other unsafe
callers have been found.
Link: http://lkml.kernel.org/r/1468014494-25291-3-git-send-email-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Reported-by: Hector Marco-Gisbert <hecmargi@upv.es>
Cc: Ismael Ripoll Ripoll <iripoll@upv.es>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There's one case when vma_adjust() expands the vma, overlapping with
*two* next vma. See case 6 of mprotect, described in the comment to
vma_merge().
To handle this (and only this) situation we iterate twice over main part
of the function. See "goto again".
Vegard reported[1] that he sees out-of-bounds access complain from
KASAN, if anon_vma_clone() on the *second* iteration fails.
This happens because we free 'next' vma by the end of first iteration
and don't have a way to undo this if anon_vma_clone() fails on the
second iteration.
The solution is to do all required allocations upfront, before we touch
vmas.
The allocation on the second iteration is only required if first two
vmas don't have anon_vma, but third does. So we need, in total, one
anon_vma_clone() call.
It's easy to adjust 'exporter' to the third vma for such case.
[1] http://lkml.kernel.org/r/1469514843-23778-1-git-send-email-vegard.nossum@oracle.com
Link: http://lkml.kernel.org/r/1469625255-126641-1-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Provide a shmem_get_unmapped_area method in file_operations, called at
mmap time to decide the mapping address. It could be conditional on
CONFIG_TRANSPARENT_HUGEPAGE, but save #ifdefs in other places by making
it unconditional.
shmem_get_unmapped_area() first calls the usual mm->get_unmapped_area
(which we treat as a black box, highly dependent on architecture and
config and executable layout). Lots of conditions, and in most cases it
just goes with the address that chose; but when our huge stars are
rightly aligned, yet that did not provide a suitable address, go back to
ask for a larger arena, within which to align the mapping suitably.
There have to be some direct calls to shmem_get_unmapped_area(), not via
the file_operations: because of the way shmem_zero_setup() is called to
create a shmem object late in the mmap sequence, when MAP_SHARED is
requested with MAP_ANONYMOUS or /dev/zero. Though this only matters
when /proc/sys/vm/shmem_huge has been set.
Link: http://lkml.kernel.org/r/1466021202-61880-29-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As with anon THP, we only mlock file huge pages if we can prove that the
page is not mapped with PTE. This way we can avoid mlock leak into
non-mlocked vma on split.
We rely on PageDoubleMap() under lock_page() to check if the the page
may be PTE mapped. PG_double_map is set by page_add_file_rmap() when
the page mapped with PTEs.
Link: http://lkml.kernel.org/r/1466021202-61880-21-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vma_addjust_trans_huge() splits pmd if it's crossing VMA boundary.
During split we munlock the huge page which requires rmap walk. rmap
wants to take the lock on its own.
Let's move vma_adjust_trans_huge() outside i_mmap_rwsem to fix this.
Link: http://lkml.kernel.org/r/1466021202-61880-19-git-send-email-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add possibility for 32-bit user-space applications to move
the vDSO mapping.
Previously, when a user-space app called mremap() for the vDSO
address, in the syscall return path it would land on the previous
address of the vDSOpage, resulting in segmentation violation.
Now it lands fine and returns to userspace with a remapped vDSO.
This will also fix the context.vdso pointer for 64-bit, which does
not affect the user of vDSO after mremap() currently, but this
may change in the future.
As suggested by Andy, return -EINVAL for mremap() that would
split the vDSO image: that operation cannot possibly result in
a working system so reject it.
Renamed and moved the text_mapping structure declaration inside
map_vdso(), as it used only there and now it complements the
vvar_mapping variable.
There is still a problem for remapping the vDSO in glibc
applications: the linker relocates addresses for syscalls
on the vDSO page, so you need to relink with the new
addresses.
Without that the next syscall through glibc may fail:
Program received signal SIGSEGV, Segmentation fault.
#0 0xf7fd9b80 in __kernel_vsyscall ()
#1 0xf7ec8238 in _exit () from /usr/lib32/libc.so.6
Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: 0x7f454c46@gmail.com
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160628113539.13606-2-dsafonov@virtuozzo.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The do_brk() and vm_brk() return value was "unsigned long" and returned
the starting address on success, and an error value on failure. The
reasons are entirely historical, and go back to it basically behaving
like the mmap() interface does.
However, nobody actually wanted that interface, and it causes totally
pointless IS_ERR_VALUE() confusion.
What every single caller actually wants is just the simpler integer
return of zero for success and negative error number on failure.
So just convert to that much clearer and more common calling convention,
and get rid of all the IS_ERR_VALUE() uses wrt vm_brk().
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that all the callers handle vm_brk failure we can change it wait for
mmap_sem killable to help oom_reaper to not get blocked just because
vm_brk gets blocked behind mmap_sem readers.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Almost all current users of vm_munmap are ignoring the return value and
so they do not handle potential error. This means that some VMAs might
stay behind. This patch doesn't try to solve those potential problems.
Quite contrary it adds a new failure mode by using down_write_killable
in vm_munmap. This should be safer than other failure modes, though,
because the process is guaranteed to die as soon as it leaves the kernel
and exit_mmap will clean the whole address space.
This will help in the OOM conditions when the oom victim might be stuck
waiting for the mmap_sem for write which in turn can block oom_reaper
which relies on the mmap_sem for read to make a forward progress and
reclaim the address space of the victim.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All the callers of vm_mmap seem to check for the failure already and
bail out in one way or another on the error which means that we can
change it to use killable version of vm_mmap_pgoff and return -EINTR if
the current task gets killed while waiting for mmap_sem. This also
means that vm_mmap_pgoff can be killable by default and drop the
additional parameter.
This will help in the OOM conditions when the oom victim might be stuck
waiting for the mmap_sem for write which in turn can block oom_reaper
which relies on the mmap_sem for read to make a forward progress and
reclaim the address space of the victim.
Please note that load_elf_binary is ignoring vm_mmap error for
current->personality & MMAP_PAGE_ZERO case but that shouldn't be a
problem because the address is not used anywhere and we never return to
the userspace if we got killed.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a follow up work for oom_reaper [1]. As the async OOM killing
depends on oom_sem for read we would really appreciate if a holder for
write didn't stood in the way. This patchset is changing many of
down_write calls to be killable to help those cases when the writer is
blocked and waiting for readers to release the lock and so help
__oom_reap_task to process the oom victim.
Most of the patches are really trivial because the lock is help from a
shallow syscall paths where we can return EINTR trivially and allow the
current task to die (note that EINTR will never get to the userspace as
the task has fatal signal pending). Others seem to be easy as well as
the callers are already handling fatal errors and bail and return to
userspace which should be sufficient to handle the failure gracefully.
I am not familiar with all those code paths so a deeper review is really
appreciated.
As this work is touching more areas which are not directly connected I
have tried to keep the CC list as small as possible and people who I
believed would be familiar are CCed only to the specific patches (all
should have received the cover though).
This patchset is based on linux-next and it depends on
down_write_killable for rw_semaphores which got merged into tip
locking/rwsem branch and it is merged into this next tree. I guess it
would be easiest to route these patches via mmotm because of the
dependency on the tip tree but if respective maintainers prefer other
way I have no objections.
I haven't covered all the mmap_write(mm->mmap_sem) instances here
$ git grep "down_write(.*\<mmap_sem\>)" next/master | wc -l
98
$ git grep "down_write(.*\<mmap_sem\>)" | wc -l
62
I have tried to cover those which should be relatively easy to review in
this series because this alone should be a nice improvement. Other
places can be changed on top.
[0] http://lkml.kernel.org/r/1456752417-9626-1-git-send-email-mhocko@kernel.org
[1] http://lkml.kernel.org/r/1452094975-551-1-git-send-email-mhocko@kernel.org
[2] http://lkml.kernel.org/r/1456750705-7141-1-git-send-email-mhocko@kernel.org
This patch (of 18):
This is the first step in making mmap_sem write waiters killable. It
focuses on the trivial ones which are taking the lock early after
entering the syscall and they are not changing state before.
Therefore it is very easy to change them to use down_write_killable and
immediately return with -EINTR. This will allow the waiter to pass away
without blocking the mmap_sem which might be required to make a forward
progress. E.g. the oom reaper will need the lock for reading to
dismantle the OOM victim address space.
The only tricky function in this patch is vm_mmap_pgoff which has many
call sites via vm_mmap. To reduce the risk keep vm_mmap with the
original non-killable semantic for now.
vm_munmap callers do not bother checking the return value so open code
it into the munmap syscall path for now for simplicity.
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since commit 8463833590 ("mm: rework virtual memory accounting")
RLIMIT_DATA limits both brk() and private mmap() but this's disabled by
default because of incompatibility with older versions of valgrind.
Valgrind always set limit to zero and fails if RLIMIT_DATA is enabled.
Fortunately it changes only rlim_cur and keeps rlim_max for reverting
limit back when needed.
This patch checks current usage also against rlim_max if rlim_cur is
zero. This is safe because task anyway can increase rlim_cur up to
rlim_max. Size of brk is still checked against rlim_cur, so this part
is completely compatible - zero rlim_cur forbids brk() but allows
private mmap().
Link: http://lkml.kernel.org/r/56A28613.5070104@de.ibm.com
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nobody uses it.
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull x86 protection key support from Ingo Molnar:
"This tree adds support for a new memory protection hardware feature
that is available in upcoming Intel CPUs: 'protection keys' (pkeys).
There's a background article at LWN.net:
https://lwn.net/Articles/643797/
The gist is that protection keys allow the encoding of
user-controllable permission masks in the pte. So instead of having a
fixed protection mask in the pte (which needs a system call to change
and works on a per page basis), the user can map a (handful of)
protection mask variants and can change the masks runtime relatively
cheaply, without having to change every single page in the affected
virtual memory range.
This allows the dynamic switching of the protection bits of large
amounts of virtual memory, via user-space instructions. It also
allows more precise control of MMU permission bits: for example the
executable bit is separate from the read bit (see more about that
below).
This tree adds the MM infrastructure and low level x86 glue needed for
that, plus it adds a high level API to make use of protection keys -
if a user-space application calls:
mmap(..., PROT_EXEC);
or
mprotect(ptr, sz, PROT_EXEC);
(note PROT_EXEC-only, without PROT_READ/WRITE), the kernel will notice
this special case, and will set a special protection key on this
memory range. It also sets the appropriate bits in the Protection
Keys User Rights (PKRU) register so that the memory becomes unreadable
and unwritable.
So using protection keys the kernel is able to implement 'true'
PROT_EXEC on x86 CPUs: without protection keys PROT_EXEC implies
PROT_READ as well. Unreadable executable mappings have security
advantages: they cannot be read via information leaks to figure out
ASLR details, nor can they be scanned for ROP gadgets - and they
cannot be used by exploits for data purposes either.
We know about no user-space code that relies on pure PROT_EXEC
mappings today, but binary loaders could start making use of this new
feature to map binaries and libraries in a more secure fashion.
There is other pending pkeys work that offers more high level system
call APIs to manage protection keys - but those are not part of this
pull request.
Right now there's a Kconfig that controls this feature
(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) that is default enabled
(like most x86 CPU feature enablement code that has no runtime
overhead), but it's not user-configurable at the moment. If there's
any serious problem with this then we can make it configurable and/or
flip the default"
* 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits)
x86/mm/pkeys: Fix mismerge of protection keys CPUID bits
mm/pkeys: Fix siginfo ABI breakage caused by new u64 field
x86/mm/pkeys: Fix access_error() denial of writes to write-only VMA
mm/core, x86/mm/pkeys: Add execute-only protection keys support
x86/mm/pkeys: Create an x86 arch_calc_vm_prot_bits() for VMA flags
x86/mm/pkeys: Allow kernel to modify user pkey rights register
x86/fpu: Allow setting of XSAVE state
x86/mm: Factor out LDT init from context init
mm/core, x86/mm/pkeys: Add arch_validate_pkey()
mm/core, arch, powerpc: Pass a protection key in to calc_vm_flag_bits()
x86/mm/pkeys: Actually enable Memory Protection Keys in the CPU
x86/mm/pkeys: Add Kconfig prompt to existing config option
x86/mm/pkeys: Dump pkey from VMA in /proc/pid/smaps
x86/mm/pkeys: Dump PKRU with other kernel registers
mm/core, x86/mm/pkeys: Differentiate instruction fetches
x86/mm/pkeys: Optimize fault handling in access_error()
mm/core: Do not enforce PKEY permissions on remote mm access
um, pkeys: Add UML arch_*_access_permitted() methods
mm/gup, x86/mm/pkeys: Check VMAs and PTEs for protection keys
x86/mm/gup: Simplify get_user_pages() PTE bit handling
...
Kernel style prefers a single string over split strings when the string is
'user-visible'.
Miscellanea:
- Add a missing newline
- Realign arguments
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Tejun Heo <tj@kernel.org> [percpu]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently we have two copies of the same code which implements memory
overcommitment logic. Let's move it into mm/util.c and hence avoid
duplication. No functional changes here.
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
max_map_count sysctl unrelated to scheduler. Move its bits from
include/linux/sched/sysctl.h to include/linux/mm.h.
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Grazvydas Ignotas has reported a regression in remap_file_pages()
emulation.
Testcase:
#define _GNU_SOURCE
#include <assert.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/mman.h>
#define SIZE (4096 * 3)
int main(int argc, char **argv)
{
unsigned long *p;
long i;
p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_ANONYMOUS, -1, 0);
if (p == MAP_FAILED) {
perror("mmap");
return -1;
}
for (i = 0; i < SIZE / 4096; i++)
p[i * 4096 / sizeof(*p)] = i;
if (remap_file_pages(p, 4096, 0, 1, 0)) {
perror("remap_file_pages");
return -1;
}
if (remap_file_pages(p, 4096 * 2, 0, 1, 0)) {
perror("remap_file_pages");
return -1;
}
assert(p[0] == 1);
munmap(p, SIZE);
return 0;
}
The second remap_file_pages() fails with -EINVAL.
The reason is that remap_file_pages() emulation assumes that the target
vma covers whole area we want to over map. That assumption is broken by
first remap_file_pages() call: it split the area into two vma.
The solution is to check next adjacent vmas, if they map the same file
with the same flags.
Fixes: c8d78c1823 ("mm: replace remap_file_pages() syscall with emulation")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Grazvydas Ignotas <notasas@gmail.com>
Tested-by: Grazvydas Ignotas <notasas@gmail.com>
Cc: <stable@vger.kernel.org> [4.0+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Protection keys provide new page-based protection in hardware.
But, they have an interesting attribute: they only affect data
accesses and never affect instruction fetches. That means that
if we set up some memory which is set as "access-disabled" via
protection keys, we can still execute from it.
This patch uses protection keys to set up mappings to do just that.
If a user calls:
mmap(..., PROT_EXEC);
or
mprotect(ptr, sz, PROT_EXEC);
(note PROT_EXEC-only without PROT_READ/WRITE), the kernel will
notice this, and set a special protection key on the memory. It
also sets the appropriate bits in the Protection Keys User Rights
(PKRU) register so that the memory becomes unreadable and
unwritable.
I haven't found any userspace that does this today. With this
facility in place, we expect userspace to move to use it
eventually. Userspace _could_ start doing this today. Any
PROT_EXEC calls get converted to PROT_READ inside the kernel, and
would transparently be upgraded to "true" PROT_EXEC with this
code. IOW, userspace never has to do any PROT_EXEC runtime
detection.
This feature provides enhanced protection against leaking
executable memory contents. This helps thwart attacks which are
attempting to find ROP gadgets on the fly.
But, the security provided by this approach is not comprehensive.
The PKRU register which controls access permissions is a normal
user register writable from unprivileged userspace. An attacker
who can execute the 'wrpkru' instruction can easily disable the
protection provided by this feature.
The protection key that is used for execute-only support is
permanently dedicated at compile time. This is fine for now
because there is currently no API to set a protection key other
than this one.
Despite there being a constant PKRU value across the entire
system, we do not set it unless this feature is in use in a
process. That is to preserve the PKRU XSAVE 'init state',
which can lead to faster context switches.
PKRU *is* a user register and the kernel is modifying it. That
means that code doing:
pkru = rdpkru()
pkru |= 0x100;
mmap(..., PROT_EXEC);
wrpkru(pkru);
could lose the bits in PKRU that enforce execute-only
permissions. To avoid this, we suggest avoiding ever calling
mmap() or mprotect() when the PKRU value is expected to be
unstable.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Piotr Kwapulinski <kwapulinski.piotr@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Vladimir Murzin <vladimir.murzin@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: keescook@google.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20160212210240.CB4BB5CA@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This plumbs a protection key through calc_vm_flag_bits(). We
could have done this in calc_vm_prot_bits(), but I did not feel
super strongly which way to go. It was pretty arbitrary which
one to use.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: David Airlie <airlied@linux.ie>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Geliang Tang <geliangtang@163.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Leon Romanovsky <leon@leon.nu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Riley Andrews <riandrews@android.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: devel@driverdev.osuosl.org
Cc: linux-api@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linuxppc-dev@lists.ozlabs.org
Link: http://lkml.kernel.org/r/20160212210231.E6F1F0D6@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Sequence vma_lock_anon_vma() - vma_unlock_anon_vma() isn't safe if
anon_vma appeared between lock and unlock. We have to check anon_vma
first or call anon_vma_prepare() to be sure that it's here. There are
only few users of these legacy helpers. Let's get rid of them.
This patch fixes anon_vma lock imbalance in validate_mm(). Write lock
isn't required here, read lock is enough.
And reorders expand_downwards/expand_upwards: security_mmap_addr() and
wrapping-around check don't have to be under anon vma lock.
Link: https://lkml.kernel.org/r/CACT4Y+Y908EjM2z=706dv4rV6dWtxTLK9nFg9_7DhRMLppBo2g@mail.gmail.com
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The mmap_sem for reading in validate_mm called from expand_stack is not
enough to prevent the argumented rbtree rb_subtree_gap information to
change from under us because expand_stack may be running from other
threads concurrently which will hold the mmap_sem for reading too.
The argumented rbtree is updated with vma_gap_update under the
page_table_lock so use it in browse_rb() too to avoid false positives.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch provides a way of working around a slight regression
introduced by commit 8463833590 ("mm: rework virtual memory
accounting").
Before that commit RLIMIT_DATA have control only over size of the brk
region. But that change have caused problems with all existing versions
of valgrind, because it set RLIMIT_DATA to zero.
This patch fixes rlimit check (limit actually in bytes, not pages) and
by default turns it into warning which prints at first VmData misuse:
"mmap: top (795): VmData 516096 exceed data ulimit 512000. Will be forbidden soon."
Behavior is controlled by boot param ignore_rlimit_data=y/n and by sysfs
/sys/module/kernel/parameters/ignore_rlimit_data. For now it set to "y".
[akpm@linux-foundation.org: tweak kernel-parameters.txt text[
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Link: http://lkml.kernel.org/r/20151228211015.GL2194@uranus
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Kees Cook <keescook@google.com>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Dmitry Vyukov has reported[1] possible deadlock (triggered by his
syzkaller fuzzer):
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&hugetlbfs_i_mmap_rwsem_key);
lock(&mapping->i_mmap_rwsem);
lock(&hugetlbfs_i_mmap_rwsem_key);
lock(&mapping->i_mmap_rwsem);
Both traces points to mm_take_all_locks() as a source of the problem.
It doesn't take care about ordering or hugetlbfs_i_mmap_rwsem_key (aka
mapping->i_mmap_rwsem for hugetlb mapping) vs. i_mmap_rwsem.
huge_pmd_share() does memory allocation under hugetlbfs_i_mmap_rwsem_key
and allocator can take i_mmap_rwsem if it hit reclaim. So we need to
take i_mmap_rwsem from all hugetlb VMAs before taking i_mmap_rwsem from
rest of VMAs.
The patch also documents locking order for hugetlbfs_i_mmap_rwsem_key.
[1] http://lkml.kernel.org/r/CACT4Y+Zu95tBs-0EvdiAKzUOsb4tczRRfCRTpLr4bg_OP9HuVg@mail.gmail.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When inspecting a vague code inside prctl(PR_SET_MM_MEM) call (which
testing the RLIMIT_DATA value to figure out if we're allowed to assign
new @start_brk, @brk, @start_data, @end_data from mm_struct) it's been
commited that RLIMIT_DATA in a form it's implemented now doesn't do
anything useful because most of user-space libraries use mmap() syscall
for dynamic memory allocations.
Linus suggested to convert RLIMIT_DATA rlimit into something suitable
for anonymous memory accounting. But in this patch we go further, and
the changes are bundled together as:
* keep vma counting if CONFIG_PROC_FS=n, will be used for limits
* replace mm->shared_vm with better defined mm->data_vm
* account anonymous executable areas as executable
* account file-backed growsdown/up areas as stack
* drop struct file* argument from vm_stat_account
* enforce RLIMIT_DATA for size of data areas
This way code looks cleaner: now code/stack/data classification depends
only on vm_flags state:
VM_EXEC & ~VM_WRITE -> code (VmExe + VmLib in proc)
VM_GROWSUP | VM_GROWSDOWN -> stack (VmStk)
VM_WRITE & ~VM_SHARED & !stack -> data (VmData)
The rest (VmSize - VmData - VmStk - VmExe - VmLib) could be called
"shared", but that might be strange beast like readonly-private or VM_IO
area.
- RLIMIT_AS limits whole address space "VmSize"
- RLIMIT_STACK limits stack "VmStk" (but each vma individually)
- RLIMIT_DATA now limits "VmData"
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Willy Tarreau <w@1wt.eu>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Kees Cook <keescook@google.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Cc: Pavel Emelyanov <xemul@virtuozzo.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Address Space Layout Randomization (ASLR) provides a barrier to
exploitation of user-space processes in the presence of security
vulnerabilities by making it more difficult to find desired code/data
which could help an attack. This is done by adding a random offset to
the location of regions in the process address space, with a greater
range of potential offset values corresponding to better protection/a
larger search-space for brute force, but also to greater potential for
fragmentation.
The offset added to the mmap_base address, which provides the basis for
the majority of the mappings for a process, is set once on process exec
in arch_pick_mmap_layout() and is done via hard-coded per-arch values,
which reflect, hopefully, the best compromise for all systems. The
trade-off between increased entropy in the offset value generation and
the corresponding increased variability in address space fragmentation
is not absolute, however, and some platforms may tolerate higher amounts
of entropy. This patch introduces both new Kconfig values and a sysctl
interface which may be used to change the amount of entropy used for
offset generation on a system.
The direct motivation for this change was in response to the
libstagefright vulnerabilities that affected Android, specifically to
information provided by Google's project zero at:
http://googleprojectzero.blogspot.com/2015/09/stagefrightened.html
The attack presented therein, by Google's project zero, specifically
targeted the limited randomness used to generate the offset added to the
mmap_base address in order to craft a brute-force-based attack.
Concretely, the attack was against the mediaserver process, which was
limited to respawning every 5 seconds, on an arm device. The hard-coded
8 bits used resulted in an average expected success rate of defeating
the mmap ASLR after just over 10 minutes (128 tries at 5 seconds a
piece). With this patch, and an accompanying increase in the entropy
value to 16 bits, the same attack would take an average expected time of
over 45 hours (32768 tries), which makes it both less feasible and more
likely to be noticed.
The introduced Kconfig and sysctl options are limited by per-arch
minimum and maximum values, the minimum of which was chosen to match the
current hard-coded value and the maximum of which was chosen so as to
give the greatest flexibility without generating an invalid mmap_base
address, generally a 3-4 bits less than the number of bits in the
user-space accessible virtual address space.
When decided whether or not to change the default value, a system
developer should consider that mmap_base address could be placed
anywhere up to 2^(value) bits away from the non-randomized location,
which would introduce variable-sized areas above and below the mmap_base
address such that the maximum vm_area_struct size may be reduced,
preventing very large allocations.
This patch (of 4):
ASLR only uses as few as 8 bits to generate the random offset for the
mmap base address on 32 bit architectures. This value was chosen to
prevent a poorly chosen value from dividing the address space in such a
way as to prevent large allocations. This may not be an issue on all
platforms. Allow the specification of a minimum number of bits so that
platforms desiring greater ASLR protection may determine where to place
the trade-off.
Signed-off-by: Daniel Cashman <dcashman@google.com>
Cc: Russell King <linux@arm.linux.org.uk>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Mark Salyzyn <salyzyn@android.com>
Cc: Jeff Vander Stoep <jeffv@google.com>
Cc: Nick Kralevich <nnk@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Hector Marco-Gisbert <hecmargi@upv.es>
Cc: Borislav Petkov <bp@suse.de>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The following flag comparison in mmap_region makes no sense:
if (!(vm_flags & MAP_FIXED))
return -ENOMEM;
The condition is always false and thus the above "return -ENOMEM" is
never executed. The vm_flags must not be compared with MAP_FIXED flag.
The vm_flags may only be compared with VM_* flags. MAP_FIXED has the
same value as VM_MAYREAD.
Hitting the rlimit is a slow path and find_vma_intersection should
realize that there is no overlapping VMA for !MAP_FIXED case pretty
quickly.
Signed-off-by: Piotr Kwapulinski <kwapulinski.piotr@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Requiring special mappings to give a list of struct pages is
inflexible: it prevents sane use of IO memory in a special
mapping, it's inefficient (it requires arch code to initialize a
list of struct pages, and it requires the mm core to walk the
entire list just to figure out how long it is), and it prevents
arch code from doing anything fancy when a special mapping fault
occurs.
Add a .fault method as an alternative to filling in a .pages
array.
Looks-OK-to: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/a26d1677c0bc7e774c33f469451a78ca31e9e6af.1451446564.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
The cost of faulting in all memory to be locked can be very high when
working with large mappings. If only portions of the mapping will be used
this can incur a high penalty for locking.
For the example of a large file, this is the usage pattern for a large
statical language model (probably applies to other statical or graphical
models as well). For the security example, any application transacting in
data that cannot be swapped out (credit card data, medical records, etc).
This patch introduces the ability to request that pages are not
pre-faulted, but are placed on the unevictable LRU when they are finally
faulted in. The VM_LOCKONFAULT flag will be used together with VM_LOCKED
and has no effect when set without VM_LOCKED. Setting the VM_LOCKONFAULT
flag for a VMA will cause pages faulted into that VMA to be added to the
unevictable LRU when they are faulted or if they are already present, but
will not cause any missing pages to be faulted in.
Exposing this new lock state means that we cannot overload the meaning of
the FOLL_POPULATE flag any longer. Prior to this patch it was used to
mean that the VMA for a fault was locked. This means we need the new
FOLL_MLOCK flag to communicate the locked state of a VMA. FOLL_POPULATE
will now only control if the VMA should be populated and in the case of
VM_LOCKONFAULT, it will not be set.
Signed-off-by: Eric B Munson <emunson@akamai.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make __install_special_mapping() args order match the caller, so the
caller can pass their register args directly to callee with no touch.
For most of architectures, args (at least the first 5th args) are in
registers, so this change will have effect on most of architectures.
For -O2, __install_special_mapping() may be inlined under most of
architectures, but for -Os, it should not. So this change can get a
little better performance for -Os, at least.
Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When fget() fails we can return -EBADF directly.
Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It is still a little better to remove it, although it should be skipped
by "-O2".
Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>=0A=
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
"mm->locked_vm += grow" and vm_stat_account() in acct_stack_growth() are
not safe; multiple threads using the same ->mm can do this at the same
time trying to expans different vma's under down_read(mmap_sem). This
means that one of the "locked_vm += grow" changes can be lost and we can
miss munlock_vma_pages_all() later.
Move this code into the caller(s) under mm->page_table_lock. All other
updates to ->locked_vm hold mmap_sem for writing.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Before the main loop, vma is already is NULL. There is no need to set it
to NULL again.
Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For VM_PFNMAP and VM_MIXEDMAP we use vm_ops->pfn_mkwrite instead of
vm_ops->page_mkwrite to notify abort write access. This means we want
vma->vm_page_prot to be write-protected if the VMA provides this vm_ops.
A theoretical scenario that will cause these missed events is:
On writable mapping with vm_ops->pfn_mkwrite, but without
vm_ops->page_mkwrite: read fault followed by write access to the pfn.
Writable pte will be set up on read fault and write fault will not be
generated.
I found it examining Dave's complaint on generic/080:
http://lkml.kernel.org/g/20150831233803.GO3902@dastard
Although I don't think it's the reason.
It shouldn't be a problem for ext2/ext4 as they provide both pfn_mkwrite
and page_mkwrite.
[akpm@linux-foundation.org: add local vm_ops to avoid 80-cols mess]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Yigal Korman <yigal@plexistor.com>
Acked-by: Boaz Harrosh <boaz@plexistor.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Revert commit 6dc296e7df "mm: make sure all file VMAs have ->vm_ops
set".
Will Deacon reports that it "causes some mmap regressions in LTP, which
appears to use a MAP_PRIVATE mmap of /dev/zero as a way to get anonymous
pages in some of its tests (specifically mmap10 [1])".
William Shuman reports Oracle crashes.
So revert the patch while we work out what to do.
Reported-by: William Shuman <wshuman3@gmail.com>
Reported-by: Will Deacon <will.deacon@arm.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We rely on vma->vm_ops == NULL to detect anonymous VMA: see
vma_is_anonymous(), but some drivers doesn't set ->vm_ops.
As a result we can end up with anonymous page in private file mapping.
That should not lead to serious misbehaviour, but nevertheless is wrong.
Let's fix by setting up dummy ->vm_ops for file mmapping if f_op->mmap()
didn't set its own.
The patch also adds sanity check into __vma_link_rb(). It will help
catch broken VMAs which inserted directly into mm_struct via
insert_vm_struct().
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add the additional "vm_flags_t vm_flags" argument to do_mmap_pgoff(),
rename it to do_mmap(), and re-introduce do_mmap_pgoff() as a simple
wrapper on top of do_mmap(). Perhaps we should update the callers of
do_mmap_pgoff() and kill it later.
This way mpx_mmap() can simply call do_mmap(vm_flags => VM_MPX) and do not
play with vm internals.
After this change mmap_region() has a single user outside of mmap.c,
arch/tile/mm/elf.c:arch_setup_additional_pages(). It would be nice to
change arch/tile/ and unexport mmap_region().
[kirill@shutemov.name: fix build]
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Tested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There's no point in initializing vma->vm_pgoff if the insertion attempt
will be failing anyway. Run the checks before performing the
initialization.
Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
__split_vma() doesn't need out_err label, neither need initializing err.
copy_vma() can return NULL directly when kmem_cache_alloc() fails.
Signed-off-by: Chen Gang <gang.chen.5i5j@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Test-case:
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <assert.h>
void *find_vdso_vaddr(void)
{
FILE *perl;
char buf[32] = {};
perl = popen("perl -e 'open STDIN,qq|/proc/@{[getppid]}/maps|;"
"/^(.*?)-.*vdso/ && print hex $1 while <>'", "r");
fread(buf, sizeof(buf), 1, perl);
fclose(perl);
return (void *)atol(buf);
}
#define PAGE_SIZE 4096
int main(void)
{
void *vdso = find_vdso_vaddr();
assert(vdso);
// of course they should differ, and they do so far
printf("vdso pages differ: %d\n",
!!memcmp(vdso, vdso + PAGE_SIZE, PAGE_SIZE));
// split into 2 vma's
assert(mprotect(vdso, PAGE_SIZE, PROT_READ) == 0);
// force another fault on the next check
assert(madvise(vdso, 2 * PAGE_SIZE, MADV_DONTNEED) == 0);
// now they no longer differ, the 2nd vm_pgoff is wrong
printf("vdso pages differ: %d\n",
!!memcmp(vdso, vdso + PAGE_SIZE, PAGE_SIZE));
return 0;
}
Output:
vdso pages differ: 1
vdso pages differ: 0
This is because split_vma() correctly updates ->vm_pgoff, but the logic
in insert_vm_struct() and special_mapping_fault() is absolutely broken,
so the fault at vdso + PAGE_SIZE return the 1st page. The same happens
if you simply unmap the 1st page.
special_mapping_fault() does:
pgoff = vmf->pgoff - vma->vm_pgoff;
and this is _only_ correct if vma->vm_start mmaps the first page from
->vm_private_data array.
vdso or any other user of install_special_mapping() is not anonymous,
it has the "backing storage" even if it is just the array of pages.
So we actually need to make vm_pgoff work as an offset in this array.
Note: this also allows to fix another problem: currently gdb can't access
"[vvar]" memory because in this case special_mapping_fault() doesn't work.
Now that we can use ->vm_pgoff we can implement ->access() and fix this.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vma->vm_userfaultfd_ctx is yet another vma parameter that vma_merge
must be aware about so that we can merge vmas back like they were
originally before arming the userfaultfd on some memory range.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Sanidhya Kashyap <sanidhya.gatech@gmail.com>
Cc: zhang.zhanghailiang@huawei.com
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Andres Lagar-Cavilla <andreslc@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Feiner <pfeiner@google.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Huangpeng (Peter)" <peter.huangpeng@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Today proc and sysfs do not contain any executable files. Several
applications today mount proc or sysfs without noexec and nosuid and
then depend on there being no exectuables files on proc or sysfs.
Having any executable files show on proc or sysfs would cause
a user space visible regression, and most likely security problems.
Therefore commit to never allowing executables on proc and sysfs by
adding a new flag to mark them as filesystems without executables and
enforce that flag.
Test the flag where MNT_NOEXEC is tested today, so that the only user
visible effect will be that exectuables will be treated as if the
execute bit is cleared.
The filesystems proc and sysfs do not currently incoporate any
executable files so this does not result in any user visible effects.
This makes it unnecessary to vet changes to proc and sysfs tightly for
adding exectuable files or changes to chattr that would modify
existing files, as no matter what the individual file say they will
not be treated as exectuable files by the vfs.
Not having to vet changes to closely is important as without this we
are only one proc_create call (or another goof up in the
implementation of notify_change) from having problematic executables
on proc. Those mistakes are all too easy to make and would create
a situation where there are security issues or the assumptions of
some program having to be broken (and cause userspace regressions).
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Souptick Joarder