linux-stable.git/fs/proc, branch v4.17

Merge branch 'speck-v20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2018-05-21T18:23:26+00:00

Merge speculative store buffer bypass fixes from Thomas Gleixner:

 - rework of the SPEC_CTRL MSR management to accomodate the new fancy
   SSBD (Speculative Store Bypass Disable) bit handling.

 - the CPU bug and sysfs infrastructure for the exciting new Speculative
   Store Bypass 'feature'.

 - support for disabling SSB via LS_CFG MSR on AMD CPUs including
   Hyperthread synchronization on ZEN.

 - PRCTL support for dynamic runtime control of SSB

 - SECCOMP integration to automatically disable SSB for sandboxed
   processes with a filter flag for opt-out.

 - KVM integration to allow guests fiddling with SSBD including the new
   software MSR VIRT_SPEC_CTRL to handle the LS_CFG based oddities on
   AMD.

 - BPF protection against SSB

.. this is just the core and x86 side, other architecture support will
come separately.

* 'speck-v20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (49 commits)
  bpf: Prevent memory disambiguation attack
  x86/bugs: Rename SSBD_NO to SSB_NO
  KVM: SVM: Implement VIRT_SPEC_CTRL support for SSBD
  x86/speculation, KVM: Implement support for VIRT_SPEC_CTRL/LS_CFG
  x86/bugs: Rework spec_ctrl base and mask logic
  x86/bugs: Remove x86_spec_ctrl_set()
  x86/bugs: Expose x86_spec_ctrl_base directly
  x86/bugs: Unify x86_spec_ctrl_{set_guest,restore_host}
  x86/speculation: Rework speculative_store_bypass_update()
  x86/speculation: Add virtualized speculative store bypass disable support
  x86/bugs, KVM: Extend speculation control for VIRT_SPEC_CTRL
  x86/speculation: Handle HT correctly on AMD
  x86/cpufeatures: Add FEATURE_ZEN
  x86/cpufeatures: Disentangle SSBD enumeration
  x86/cpufeatures: Disentangle MSR_SPEC_CTRL enumeration from IBRS
  x86/speculation: Use synthetic bits for IBRS/IBPB/STIBP
  KVM: SVM: Move spec control call after restore of GS
  x86/cpu: Make alternative_msr_write work for 32-bit code
  x86/bugs: Fix the parameters alignment and missing void
  x86/bugs: Make cpu_show_common() static
  ...

proc: do not access cmdline nor environ from file-backed areas

2018-05-17T16:27:47+00:00

proc_pid_cmdline_read() and environ_read() directly access the target
process' VM to retrieve the command line and environment. If this
process remaps these areas onto a file via mmap(), the requesting
process may experience various issues such as extra delays if the
underlying device is slow to respond.

Let's simply refuse to access file-backed areas in these functions.
For this we add a new FOLL_ANON gup flag that is passed to all calls
to access_remote_vm(). The code already takes care of such failures
(including unmapped areas). Accesses via /proc/pid/mem were not
changed though.

This was assigned CVE-2018-1120.

Note for stable backports: the patch may apply to kernels prior to 4.11
but silently miss one location; it must be checked that no call to
access_remote_vm() keeps zero as the last argument.

Reported-by: Qualys Security Advisory 
Cc: Linus Torvalds 
Cc: Andy Lutomirski 
Cc: Oleg Nesterov 
Cc: stable@vger.kernel.org
Signed-off-by: Willy Tarreau 
Signed-off-by: Linus Torvalds

proc/kcore: don't bounds check against address 0

2018-05-12T00:28:45+00:00

The existing kcore code checks for bad addresses against __va(0) with
the assumption that this is the lowest address on the system.  This may
not hold true on some systems (e.g.  arm64) and produce overflows and
crashes.  Switch to using other functions to validate the address range.

It's currently only seen on arm64 and it's not clear if anyone wants to
use that particular combination on a stable release.  So this is not
urgent for stable.

Link: http://lkml.kernel.org/r/20180501201143.15121-1-labbott@redhat.com
Signed-off-by: Laura Abbott 
Tested-by: Dave Anderson 
Cc: Kees Cook 
Cc: Ard Biesheuvel 
Cc: Ingo Molnar 
Cc: Andi Kleen 
Cc: Alexey Dobriyan a
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: Use underscores for SSBD in 'status'

2018-05-09T19:41:38+00:00

The style for the 'status' file is CamelCase or this. _.

Fixes: fae1fa0fc ("proc: Provide details on speculation flaw mitigations")
Signed-off-by: Konrad Rzeszutek Wilk 
Signed-off-by: Thomas Gleixner

prctl: Add force disable speculation

2018-05-04T22:51:43+00:00

For certain use cases it is desired to enforce mitigations so they cannot
be undone afterwards. That's important for loader stubs which want to
prevent a child from disabling the mitigation again. Will also be used for
seccomp(). The extra state preserving of the prctl state for SSB is a
preparatory step for EBPF dymanic speculation control.

Signed-off-by: Thomas Gleixner

proc: Provide details on speculation flaw mitigations

2018-05-03T11:55:51+00:00

As done with seccomp and no_new_privs, also show speculation flaw
mitigation state in /proc/$pid/status.

Signed-off-by: Kees Cook 
Signed-off-by: Thomas Gleixner

proc: fix /proc/loadavg regression

2018-04-21T00:18:36+00:00

Commit 95846ecf9dac ("pid: replace pid bitmap implementation with IDR
API") changed last field of /proc/loadavg (last pid allocated) to be off
by one:

	# unshare -p -f --mount-proc cat /proc/loadavg
	0.00 0.00 0.00 1/60 2	<===

It should be 1 after first fork into pid namespace.

This is formally a regression but given how useless this field is I
don't think anyone is affected.

Bug was found by /proc testsuite!

Link: http://lkml.kernel.org/r/20180413175408.GA27246@avx2
Fixes: 95846ecf9dac508 ("pid: replace pid bitmap implementation with IDR API")
Signed-off-by: Alexey Dobriyan 
Cc: "Eric W. Biederman" 
Cc: Gargi Sharma 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: revalidate kernel thread inodes to root:root

2018-04-21T00:18:35+00:00

task_dump_owner() has the following code:

	mm = task->mm;
	if (mm) {
		if (get_dumpable(mm) != SUID_DUMP_USER) {
			uid = ...
		}
	}

Check for ->mm is buggy -- kernel thread might be borrowing mm
and inode will go to some random uid:gid pair.

Link: http://lkml.kernel.org/r/20180412220109.GA20978@avx2
Signed-off-by: Alexey Dobriyan 
Cc: "Eric W. Biederman" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, pagemap: fix swap offset value for PMD migration entry

2018-04-21T00:18:35+00:00

The swap offset reported by /proc//pagemap may be not correct for
PMD migration entries.  If addr passed into pagemap_pmd_range() isn't
aligned with PMD start address, the swap offset reported doesn't
reflect this.  And in the loop to report information of each sub-page,
the swap offset isn't increased accordingly as that for PFN.

This may happen after opening /proc//pagemap and seeking to a page
whose address doesn't align with a PMD start address.  I have verified
this with a simple test program.

BTW: migration swap entries have PFN information, do we need to restrict
whether to show them?

[akpm@linux-foundation.org: fix typo, per Huang, Ying]
Link: http://lkml.kernel.org/r/20180408033737.10897-1-ying.huang@intel.com
Signed-off-by: "Huang, Ying" 
Cc: Michal Hocko 
Cc: "Kirill A. Shutemov" 
Cc: Andrei Vagin 
Cc: Dan Williams 
Cc: "Jerome Glisse" 
Cc: Daniel Colascione 
Cc: Zi Yan 
Cc: Naoya Horiguchi 
Cc: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: revalidate misc dentries

2018-04-14T00:10:27+00:00

If module removes proc directory while another process pins it by
chdir'ing to it, then subsequent recreation of proc entry and all
entries down the tree will not be visible to any process until pinning
process unchdir from directory and unpins everything.

Steps to reproduce:

	proc_mkdir("aaa", NULL);
	proc_create("aaa/bbb", ...);

		chdir("/proc/aaa");

	remove_proc_entry("aaa/bbb", NULL);
	remove_proc_entry("aaa", NULL);

	proc_mkdir("aaa", NULL);
	# inaccessible because "aaa" dentry still points
	# to the original "aaa".
	proc_create("aaa/bbb", ...);

Fix is to implement ->d_revalidate and ->d_delete.

Link: http://lkml.kernel.org/r/20180312201938.GA4871@avx2
Signed-off-by: Alexey Dobriyan 
Cc: Al Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds