linux-stable.git/include/linux/sched.h, branch v4.1.41

sched, cgroup: reorganize threadgroup locking

2017-06-08T02:52:05+00:00

[ Upstream commit 7d7efec368d537226142cbe559f45797f18672f9 ]

threadgroup_change_begin/end() are used to mark the beginning and end
of threadgroup modifying operations to allow code paths which require
a threadgroup to stay stable across blocking operations to synchronize
against those sections using threadgroup_lock/unlock().

It's currently implemented as a general mechanism in sched.h using
per-signal_struct rwsem; however, this never grew non-cgroup use cases
and becomes noop if !CONFIG_CGROUPS.  It turns out that cgroups is
gonna be better served with a different sycnrhonization scheme and is
a bit silly to keep cgroups specific details as a general mechanism.

What's general here is identifying the places where threadgroups are
modified.  This patch restructures threadgroup locking so that
threadgroup_change_begin/end() become a place where subsystems which
need to sycnhronize against threadgroup changes can hook into.

cgroup_threadgroup_change_begin/end() which operate on the
per-signal_struct rwsem are created and threadgroup_lock/unlock() are
moved to cgroup.c and made static.

This is pure reorganization which doesn't cause any functional
changes.

Signed-off-by: Tejun Heo 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Signed-off-by: Sasha Levin

ptrace: Capture the ptracer's creds not PT_PTRACE_CAP

2017-03-03T02:51:40+00:00

[ Upstream commit 64b875f7ac8a5d60a4e191479299e931ee949b67 ]

When the flag PT_PTRACE_CAP was added the PTRACE_TRACEME path was
overlooked.  This can result in incorrect behavior when an application
like strace traces an exec of a setuid executable.

Further PT_PTRACE_CAP does not have enough information for making good
security decisions as it does not report which user namespace the
capability is in.  This has already allowed one mistake through
insufficient granulariy.

I found this issue when I was testing another corner case of exec and
discovered that I could not get strace to set PT_PTRACE_CAP even when
running strace as root with a full set of caps.

This change fixes the above issue with strace allowing stracing as
root a setuid executable without disabling setuid.  More fundamentaly
this change allows what is allowable at all times, by using the correct
information in it's decision.

Cc: stable@vger.kernel.org
Fixes: 4214e42f96d4 ("v2.4.9.11 -> v2.4.9.12")
Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Sasha Levin

pipe: limit the per-user amount of pages allocated in pipes

2016-07-11T03:07:27+00:00

[ Upstream commit 759c01142a5d0f364a462346168a56de28a80f52 ]

On no-so-small systems, it is possible for a single process to cause an
OOM condition by filling large pipes with data that are never read. A
typical process filling 4000 pipes with 1 MB of data will use 4 GB of
memory. On small systems it may be tricky to set the pipe max size to
prevent this from happening.

This patch makes it possible to enforce a per-user soft limit above
which new pipes will be limited to a single page, effectively limiting
them to 4 kB each, as well as a hard limit above which no new pipes may
be created for this user. This has the effect of protecting the system
against memory abuse without hurting other users, and still allowing
pipes to work correctly though with less data at once.

The limit are controlled by two new sysctls : pipe-user-pages-soft, and
pipe-user-pages-hard. Both may be disabled by setting them to zero. The
default soft limit allows the default number of FDs per process (1024)
to create pipes of the default size (64kB), thus reaching a limit of 64MB
before starting to create only smaller pipes. With 256 processes limited
to 1024 FDs each, this results in 1024*64kB + (256*1024 - 1024) * 4kB =
1084 MB of memory allocated for a user. The hard limit is disabled by
default to avoid breaking existing applications that make intensive use
of pipes (eg: for splicing).

Reported-by: socketpair@gmail.com
Reported-by: Tetsuo Handa 
Mitigates: CVE-2013-4312 (Linux 2.0+)
Suggested-by: Linus Torvalds 
Signed-off-by: Willy Tarreau 
Signed-off-by: Al Viro 
Signed-off-by: Sasha Levin

unix: properly account for FDs passed over unix sockets

2016-01-31T19:23:36+00:00

[ Upstream commit 712f4aad406bb1ed67f3f98d04c044191f0ff593 ]

It is possible for a process to allocate and accumulate far more FDs than
the process' limit by sending them over a unix socket then closing them
to keep the process' fd count low.

This change addresses this problem by keeping track of the number of FDs
in flight per user and preventing non-privileged processes from having
more FDs in flight than their configured FD limit.

Reported-by: socketpair@gmail.com
Reported-by: Tetsuo Handa 
Mitigates: CVE-2013-4312 (Linux 2.0+)
Suggested-by: Linus Torvalds 
Acked-by: Hannes Frederic Sowa 
Signed-off-by: Willy Tarreau 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

sched/preempt: Fix cond_resched_lock() and cond_resched_softirq()

2015-10-27T00:51:58+00:00

commit fe32d3cd5e8eb0f82e459763374aa80797023403 upstream.

These functions check should_resched() before unlocking spinlock/bh-enable:
preempt_count always non-zero => should_resched() always returns false.
cond_resched_lock() worked iff spin_needbreak is set.

This patch adds argument "preempt_offset" to should_resched().

preempt_count offset constants for that:

  PREEMPT_DISABLE_OFFSET  - offset after preempt_disable()
  PREEMPT_LOCK_OFFSET     - offset after spin_lock()
  SOFTIRQ_DISABLE_OFFSET  - offset after local_bh_distable()
  SOFTIRQ_LOCK_OFFSET     - offset after spin_lock_bh()

Signed-off-by: Konstantin Khlebnikov 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: Alexander Graf 
Cc: Boris Ostrovsky 
Cc: David Vrabel 
Cc: Linus Torvalds 
Cc: Mike Galbraith 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Fixes: bdb438065890 ("sched: Extract the basic add/sub preempt_count modifiers")
Link: http://lkml.kernel.org/r/20150715095204.12246.98268.stgit@buzz
Signed-off-by: Ingo Molnar 
Signed-off-by: Mike Galbraith 
Signed-off-by: Greg Kroah-Hartman

x86: pvclock: Really remove the sched notifier for cross-cpu migrations

2015-04-27T13:49:30+00:00

This reverts commits 0a4e6be9ca17c54817cf814b4b5aa60478c6df27
and 80f7fdb1c7f0f9266421f823964fd1962681f6ce.

The task migration notifier was originally introduced in order to support
the pvclock vsyscall with non-synchronized TSC, but KVM only supports it
with synchronized TSC.  Hence, on KVM the race condition is only needed
due to a bad implementation on the host side, and even then it's so rare
that it's mostly theoretical.

As far as KVM is concerned it's possible to fix the host, avoiding the
additional complexity in the vDSO and the (re)introduction of the task
migration notifier.

Xen, on the other hand, hasn't yet implemented vsyscall support at
all, so we do not care about its plans for non-synchronized TSC.

Reported-by: Peter Zijlstra 
Suggested-by: Marcelo Tosatti 
Signed-off-by: Paolo Bonzini

Merge branch 'exec_domain_rip_v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc

2015-04-15T20:53:55+00:00

Pull exec domain removal from Richard Weinberger:
 "This series removes execution domain support from Linux.

  The idea behind exec domains was to support different ABIs.  The
  feature was never complete nor stable.  Let's rip it out and make the
  kernel signal handling code less complicated"

* 'exec_domain_rip_v2' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/misc: (27 commits)
  arm64: Removed unused variable
  sparc: Fix execution domain removal
  Remove rest of exec domains.
  arch: Remove exec_domain from remaining archs
  arc: Remove signal translation and exec_domain
  xtensa: Remove signal translation and exec_domain
  xtensa: Autogenerate offsets in struct thread_info
  x86: Remove signal translation and exec_domain
  unicore32: Remove signal translation and exec_domain
  um: Remove signal translation and exec_domain
  tile: Remove signal translation and exec_domain
  sparc: Remove signal translation and exec_domain
  sh: Remove signal translation and exec_domain
  s390: Remove signal translation and exec_domain
  mn10300: Remove signal translation and exec_domain
  microblaze: Remove signal translation and exec_domain
  m68k: Remove signal translation and exec_domain
  m32r: Remove signal translation and exec_domain
  m32r: Autogenerate offsets in struct thread_info
  frv: Remove signal translation and exec_domain
  ...

Merge branch 'for-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2015-04-13T23:47:11+00:00

Pull cgroup updates from Tejun Heo:
 "Nothing too interesting.  Rik made cpuset cooperate better with
  isolcpus and there are several other cleanup patches"

* 'for-4.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cpuset, isolcpus: document relationship between cpusets & isolcpus
  cpusets, isolcpus: exclude isolcpus from load balancing in cpusets
  sched, isolcpu: make cpu_isolated_map visible outside scheduler
  cpuset: initialize cpuset a bit early
  cgroup: Use kvfree in pidlist_free()
  cgroup: call cgroup_subsys->bind on cgroup subsys initialization

Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2015-04-13T17:47:34+00:00

Pull scheduler changes from Ingo Molnar:
 "Major changes:

   - Reworked CPU capacity code, for better SMP load balancing on
     systems with assymetric CPUs. (Vincent Guittot, Morten Rasmussen)

   - Reworked RT task SMP balancing to be push based instead of pull
     based, to reduce latencies on large CPU count systems. (Steven
     Rostedt)

   - SCHED_DEADLINE support updates and fixes. (Juri Lelli)

   - SCHED_DEADLINE task migration support during CPU hotplug. (Wanpeng Li)

   - x86 mwait-idle optimizations and fixes. (Mike Galbraith, Len Brown)

   - sched/numa improvements. (Rik van Riel)

   - various cleanups"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (28 commits)
  sched/core: Drop debugging leftover trace_printk call
  sched/deadline: Support DL task migration during CPU hotplug
  sched/core: Check for available DL bandwidth in cpuset_cpu_inactive()
  sched/deadline: Always enqueue on previous rq when dl_task_timer() fires
  sched/core: Remove unused argument from init_[rt|dl]_rq()
  sched/deadline: Fix rt runtime corruption when dl fails its global constraints
  sched/deadline: Avoid a superfluous check
  sched: Improve load balancing in the presence of idle CPUs
  sched: Optimize freq invariant accounting
  sched: Move CFS tasks to CPUs with higher capacity
  sched: Add SD_PREFER_SIBLING for SMT level
  sched: Remove unused struct sched_group_capacity::capacity_orig
  sched: Replace capacity_factor by usage
  sched: Calculate CPU's usage statistic and put it into struct sg_lb_stats::group_usage
  sched: Add struct rq::cpu_capacity_orig
  sched: Make scale_rt invariant with frequency
  sched: Make sched entity usage tracking scale-invariant
  sched: Remove frequency scaling from cpu_capacity
  sched: Track group sched_entity usage contributions
  sched: Add sched_avg::utilization_avg_contrib
  ...

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2015-04-13T16:47:01+00:00

Pull KVM updates from Paolo Bonzini:
 "First batch of KVM changes for 4.1

  The most interesting bit here is irqfd/ioeventfd support for ARM and
  ARM64.

  Summary:

  ARM/ARM64:
     fixes for live migration, irqfd and ioeventfd support (enabling
     vhost, too), page aging

  s390:
     interrupt handling rework, allowing to inject all local interrupts
     via new ioctl and to get/set the full local irq state for migration
     and introspection.  New ioctls to access memory by virtual address,
     and to get/set the guest storage keys.  SIMD support.

  MIPS:
     FPU and MIPS SIMD Architecture (MSA) support.  Includes some
     patches from Ralf Baechle's MIPS tree.

  x86:
     bugfixes (notably for pvclock, the others are small) and cleanups.
     Another small latency improvement for the TSC deadline timer"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (146 commits)
  KVM: use slowpath for cross page cached accesses
  kvm: mmu: lazy collapse small sptes into large sptes
  KVM: x86: Clear CR2 on VCPU reset
  KVM: x86: DR0-DR3 are not clear on reset
  KVM: x86: BSP in MSR_IA32_APICBASE is writable
  KVM: x86: simplify kvm_apic_map
  KVM: x86: avoid logical_map when it is invalid
  KVM: x86: fix mixed APIC mode broadcast
  KVM: x86: use MDA for interrupt matching
  kvm/ppc/mpic: drop unused IRQ_testbit
  KVM: nVMX: remove unnecessary double caching of MAXPHYADDR
  KVM: nVMX: checks for address bits beyond MAXPHYADDR on VM-entry
  KVM: x86: cache maxphyaddr CPUID leaf in struct kvm_vcpu
  KVM: vmx: pass error code with internal error #2
  x86: vdso: fix pvclock races with task migration
  KVM: remove kvm_read_hva and kvm_read_hva_atomic
  KVM: x86: optimize delivery of TSC deadline timer interrupt
  KVM: x86: extract blocking logic from __vcpu_run
  kvm: x86: fix x86 eflags fixed bit
  KVM: s390: migrate vcpu interrupt state
  ...