commit ccf61486fe upstream.
Due to an oversight in commit 1b3044e39a ("procfs: fix pthread
cross-thread naming if !PR_DUMPABLE") in switching from REG to NOD,
chmod operations on /proc/thread-self/comm were no longer blocked as
they are on almost all other procfs files.
A very similar situation with /proc/self/environ was used to as a root
exploit a long time ago, but procfs has SB_I_NOEXEC so this is simply a
correctness issue.
Ref: https://lwn.net/Articles/191954/
Ref: 6d76fa58b0 ("Don't allow chmod() on the /proc/<pid>/ files")
Fixes: 1b3044e39a ("procfs: fix pthread cross-thread naming if !PR_DUMPABLE")
Cc: stable@vger.kernel.org # v4.7+
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Message-Id: <20230713141001.27046-1-cyphar@cyphar.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
linux-next for a couple of months without, to my knowledge, any negative
reports (or any positive ones, come to that).
- Also the Maple Tree from Liam R. Howlett. An overlapping range-based
tree for vmas. It it apparently slight more efficient in its own right,
but is mainly targeted at enabling work to reduce mmap_lock contention.
Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.
Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
(https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com).
This has yet to be addressed due to Liam's unfortunately timed
vacation. He is now back and we'll get this fixed up.
- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down to
the single bit level.
KMSAN keeps finding bugs. New ones, as well as the legacy ones.
- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.
- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to support
file/shmem-backed pages.
- userfaultfd updates from Axel Rasmussen
- zsmalloc cleanups from Alexey Romanov
- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and memory-failure
- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.
- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.
- memcg cleanups from Kairui Song.
- memcg fixes and cleanups from Johannes Weiner.
- Vishal Moola provides more folio conversions
- Zhang Yi removed ll_rw_block() :(
- migration enhancements from Peter Xu
- migration error-path bugfixes from Huang Ying
- Aneesh Kumar added ability for a device driver to alter the memory
tiering promotion paths. For optimizations by PMEM drivers, DRM
drivers, etc.
- vma merging improvements from Jakub Matěn.
- NUMA hinting cleanups from David Hildenbrand.
- xu xin added aditional userspace visibility into KSM merging activity.
- THP & KSM code consolidation from Qi Zheng.
- more folio work from Matthew Wilcox.
- KASAN updates from Andrey Konovalov.
- DAMON cleanups from Kaixu Xia.
- DAMON work from SeongJae Park: fixes, cleanups.
- hugetlb sysfs cleanups from Muchun Song.
- Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.
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Merge tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
linux-next for a couple of months without, to my knowledge, any
negative reports (or any positive ones, come to that).
- Also the Maple Tree from Liam Howlett. An overlapping range-based
tree for vmas. It it apparently slightly more efficient in its own
right, but is mainly targeted at enabling work to reduce mmap_lock
contention.
Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.
Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
at [1]. This has yet to be addressed due to Liam's unfortunately
timed vacation. He is now back and we'll get this fixed up.
- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down
to the single bit level.
KMSAN keeps finding bugs. New ones, as well as the legacy ones.
- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.
- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to
support file/shmem-backed pages.
- userfaultfd updates from Axel Rasmussen
- zsmalloc cleanups from Alexey Romanov
- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and
memory-failure
- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.
- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.
- memcg cleanups from Kairui Song.
- memcg fixes and cleanups from Johannes Weiner.
- Vishal Moola provides more folio conversions
- Zhang Yi removed ll_rw_block() :(
- migration enhancements from Peter Xu
- migration error-path bugfixes from Huang Ying
- Aneesh Kumar added ability for a device driver to alter the memory
tiering promotion paths. For optimizations by PMEM drivers, DRM
drivers, etc.
- vma merging improvements from Jakub Matěn.
- NUMA hinting cleanups from David Hildenbrand.
- xu xin added aditional userspace visibility into KSM merging
activity.
- THP & KSM code consolidation from Qi Zheng.
- more folio work from Matthew Wilcox.
- KASAN updates from Andrey Konovalov.
- DAMON cleanups from Kaixu Xia.
- DAMON work from SeongJae Park: fixes, cleanups.
- hugetlb sysfs cleanups from Muchun Song.
- Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.
Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1]
* tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits)
hugetlb: allocate vma lock for all sharable vmas
hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer
hugetlb: fix vma lock handling during split vma and range unmapping
mglru: mm/vmscan.c: fix imprecise comments
mm/mglru: don't sync disk for each aging cycle
mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol
mm: memcontrol: use do_memsw_account() in a few more places
mm: memcontrol: deprecate swapaccounting=0 mode
mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled
mm/secretmem: remove reduntant return value
mm/hugetlb: add available_huge_pages() func
mm: remove unused inline functions from include/linux/mm_inline.h
selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory
selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd
selftests/vm: add thp collapse shmem testing
selftests/vm: add thp collapse file and tmpfs testing
selftests/vm: modularize thp collapse memory operations
selftests/vm: dedup THP helpers
mm/khugepaged: add tracepoint to hpage_collapse_scan_file()
mm/madvise: add file and shmem support to MADV_COLLAPSE
...
Patch series "ksm: count allocated rmap_items and update documentation",
v5.
KSM can save memory by merging identical pages, but also can consume
additional memory, because it needs to generate rmap_items to save each
scanned page's brief rmap information.
To determine how beneficial the ksm-policy (like madvise), they are using
brings, so we add a new interface /proc/<pid>/ksm_stat for each process
The value "ksm_rmap_items" in it indicates the total allocated ksm
rmap_items of this process.
The detailed description can be seen in the following patches' commit
message.
This patch (of 2):
KSM can save memory by merging identical pages, but also can consume
additional memory, because it needs to generate rmap_items to save each
scanned page's brief rmap information. Some of these pages may be merged,
but some may not be abled to be merged after being checked several times,
which are unprofitable memory consumed.
The information about whether KSM save memory or consume memory in
system-wide range can be determined by the comprehensive calculation of
pages_sharing, pages_shared, pages_unshared and pages_volatile. A simple
approximate calculation:
profit =~ pages_sharing * sizeof(page) - (all_rmap_items) *
sizeof(rmap_item);
where all_rmap_items equals to the sum of pages_sharing, pages_shared,
pages_unshared and pages_volatile.
But we cannot calculate this kind of ksm profit inner single-process wide
because the information of ksm rmap_item's number of a process is lacked.
For user applications, if this kind of information could be obtained, it
helps upper users know how beneficial the ksm-policy (like madvise) they
are using brings, and then optimize their app code. For example, one
application madvise 1000 pages as MERGEABLE, while only a few pages are
really merged, then it's not cost-efficient.
So we add a new interface /proc/<pid>/ksm_stat for each process in which
the value of ksm_rmap_itmes is only shown now and so more values can be
added in future.
So similarly, we can calculate the ksm profit approximately for a single
process by:
profit =~ ksm_merging_pages * sizeof(page) - ksm_rmap_items *
sizeof(rmap_item);
where ksm_merging_pages is shown at /proc/<pid>/ksm_merging_pages, and
ksm_rmap_items is shown in /proc/<pid>/ksm_stat.
Link: https://lkml.kernel.org/r/20220830143731.299702-1-xu.xin16@zte.com.cn
Link: https://lkml.kernel.org/r/20220830143838.299758-1-xu.xin16@zte.com.cn
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Reviewed-by: Xiaokai Ran <ran.xiaokai@zte.com.cn>
Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
Signed-off-by: CGEL ZTE <cgel.zte@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Izik Eidus <izik.eidus@ravellosystems.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Use the vma iterator instead of a for loop across the linked list. The
link list of vmas will be removed in this patch set.
Link: https://lkml.kernel.org/r/20220906194824.2110408-43-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
cast of ->d_name.name to char * is completely wrong - nothing is
allowed to modify its contents.
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit 7bc3e6e55a ("proc: Use a list of inodes to flush from proc")
moved proc_flush_task() behind __exit_signal(). Then, process systemd can
take long period high cpu usage during releasing task in following
concurrent processes:
systemd ps
kernel_waitid stat(/proc/tgid)
do_wait filename_lookup
wait_consider_task lookup_fast
release_task
__exit_signal
__unhash_process
detach_pid
__change_pid // remove task->pid_links
d_revalidate -> pid_revalidate // 0
d_invalidate(/proc/tgid)
shrink_dcache_parent(/proc/tgid)
d_walk(/proc/tgid)
spin_lock_nested(/proc/tgid/fd)
// iterating opened fd
proc_flush_pid |
d_invalidate (/proc/tgid/fd) |
shrink_dcache_parent(/proc/tgid/fd) |
shrink_dentry_list(subdirs) ↓
shrink_lock_dentry(/proc/tgid/fd) --> race on dentry lock
Function d_invalidate() will remove dentry from hash firstly, but why does
proc_flush_pid() process dentry '/proc/tgid/fd' before dentry
'/proc/tgid'? That's because proc_pid_make_inode() adds proc inode in
reverse order by invoking hlist_add_head_rcu(). But proc should not add
any inodes under '/proc/tgid' except '/proc/tgid/task/pid', fix it by
adding inode into 'pid->inodes' only if the inode is /proc/tgid or
/proc/tgid/task/pid.
Performance regression:
Create 200 tasks, each task open one file for 50,000 times. Kill all
tasks when opened files exceed 10,000,000 (cat /proc/sys/fs/file-nr).
Before fix:
$ time killall -wq aa
real 4m40.946s # During this period, we can see 'ps' and 'systemd'
taking high cpu usage.
After fix:
$ time killall -wq aa
real 1m20.732s # During this period, we can see 'systemd' taking
high cpu usage.
Link: https://lkml.kernel.org/r/20220713130029.4133533-1-chengzhihao1@huawei.com
Fixes: 7bc3e6e55a ("proc: Use a list of inodes to flush from proc")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216054
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Suggested-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Some applications or containers want to use KSM by calling madvise() to
advise areas of address space to be MERGEABLE. But they may not know
which applications are more likely to cause real merges in the
deployment. If this patch is applied, it helps them know their
corresponding number of merged pages, and then optimize their app code.
As current KSM only counts the number of KSM merging pages(e.g.
ksm_pages_sharing and ksm_pages_shared) of the whole system, we cannot see
the more fine-grained KSM merging, for the upper application optimization,
the merging area cannot be set easily according to the KSM page merging
probability of each process. Therefore, it is necessary to add extra
statistical means so that the upper level users can know the detailed KSM
merging information of each process.
We add a new proc file named as ksm_merging_pages under /proc/<pid>/ to
indicate the involved ksm merging pages of this process.
[akpm@linux-foundation.org: fix comment typo, remove BUG_ON()s]
Link: https://lkml.kernel.org/r/20220325082318.2352853-1-xu.xin16@zte.com.cn
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Yang Yang <yang.yang29@zte.com.cn>
Reviewed-by: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Reported-by: Zeal Robot <zealci@zte.com.cn>
Cc: Kees Cook <keescook@chromium.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Ohhoon Kwon <ohoono.kwon@samsung.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Stephen Brennan <stephen.s.brennan@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Yang Yang <yang.yang29@zte.com.cn>
Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Cc: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This set of changes removes tracehook.h, moves modification of all of
the ptrace fields inside of siglock to remove races, adds a missing
permission check to ptrace.c
The removal of tracehook.h is quite significant as it has been a major
source of confusion in recent years. Much of that confusion was
around task_work and TIF_NOTIFY_SIGNAL (which I have now decoupled
making the semantics clearer).
For people who don't know tracehook.h is a vestiage of an attempt to
implement uprobes like functionality that was never fully merged, and
was later superseeded by uprobes when uprobes was merged. For many
years now we have been removing what tracehook functionaly a little
bit at a time. To the point where now anything left in tracehook.h is
some weird strange thing that is difficult to understand.
Eric W. Biederman (15):
ptrace: Move ptrace_report_syscall into ptrace.h
ptrace/arm: Rename tracehook_report_syscall report_syscall
ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h
ptrace: Remove arch_syscall_{enter,exit}_tracehook
ptrace: Remove tracehook_signal_handler
task_work: Remove unnecessary include from posix_timers.h
task_work: Introduce task_work_pending
task_work: Call tracehook_notify_signal from get_signal on all architectures
task_work: Decouple TIF_NOTIFY_SIGNAL and task_work
signal: Move set_notify_signal and clear_notify_signal into sched/signal.h
resume_user_mode: Remove #ifdef TIF_NOTIFY_RESUME in set_notify_resume
resume_user_mode: Move to resume_user_mode.h
tracehook: Remove tracehook.h
ptrace: Move setting/clearing ptrace_message into ptrace_stop
ptrace: Return the signal to continue with from ptrace_stop
Jann Horn (1):
ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE
Yang Li (1):
ptrace: Remove duplicated include in ptrace.c
MAINTAINERS | 1 -
arch/Kconfig | 5 +-
arch/alpha/kernel/ptrace.c | 5 +-
arch/alpha/kernel/signal.c | 4 +-
arch/arc/kernel/ptrace.c | 5 +-
arch/arc/kernel/signal.c | 4 +-
arch/arm/kernel/ptrace.c | 12 +-
arch/arm/kernel/signal.c | 4 +-
arch/arm64/kernel/ptrace.c | 14 +--
arch/arm64/kernel/signal.c | 4 +-
arch/csky/kernel/ptrace.c | 5 +-
arch/csky/kernel/signal.c | 4 +-
arch/h8300/kernel/ptrace.c | 5 +-
arch/h8300/kernel/signal.c | 4 +-
arch/hexagon/kernel/process.c | 4 +-
arch/hexagon/kernel/signal.c | 1 -
arch/hexagon/kernel/traps.c | 6 +-
arch/ia64/kernel/process.c | 4 +-
arch/ia64/kernel/ptrace.c | 6 +-
arch/ia64/kernel/signal.c | 1 -
arch/m68k/kernel/ptrace.c | 5 +-
arch/m68k/kernel/signal.c | 4 +-
arch/microblaze/kernel/ptrace.c | 5 +-
arch/microblaze/kernel/signal.c | 4 +-
arch/mips/kernel/ptrace.c | 5 +-
arch/mips/kernel/signal.c | 4 +-
arch/nds32/include/asm/syscall.h | 2 +-
arch/nds32/kernel/ptrace.c | 5 +-
arch/nds32/kernel/signal.c | 4 +-
arch/nios2/kernel/ptrace.c | 5 +-
arch/nios2/kernel/signal.c | 4 +-
arch/openrisc/kernel/ptrace.c | 5 +-
arch/openrisc/kernel/signal.c | 4 +-
arch/parisc/kernel/ptrace.c | 7 +-
arch/parisc/kernel/signal.c | 4 +-
arch/powerpc/kernel/ptrace/ptrace.c | 8 +-
arch/powerpc/kernel/signal.c | 4 +-
arch/riscv/kernel/ptrace.c | 5 +-
arch/riscv/kernel/signal.c | 4 +-
arch/s390/include/asm/entry-common.h | 1 -
arch/s390/kernel/ptrace.c | 1 -
arch/s390/kernel/signal.c | 5 +-
arch/sh/kernel/ptrace_32.c | 5 +-
arch/sh/kernel/signal_32.c | 4 +-
arch/sparc/kernel/ptrace_32.c | 5 +-
arch/sparc/kernel/ptrace_64.c | 5 +-
arch/sparc/kernel/signal32.c | 1 -
arch/sparc/kernel/signal_32.c | 4 +-
arch/sparc/kernel/signal_64.c | 4 +-
arch/um/kernel/process.c | 4 +-
arch/um/kernel/ptrace.c | 5 +-
arch/x86/kernel/ptrace.c | 1 -
arch/x86/kernel/signal.c | 5 +-
arch/x86/mm/tlb.c | 1 +
arch/xtensa/kernel/ptrace.c | 5 +-
arch/xtensa/kernel/signal.c | 4 +-
block/blk-cgroup.c | 2 +-
fs/coredump.c | 1 -
fs/exec.c | 1 -
fs/io-wq.c | 6 +-
fs/io_uring.c | 11 +-
fs/proc/array.c | 1 -
fs/proc/base.c | 1 -
include/asm-generic/syscall.h | 2 +-
include/linux/entry-common.h | 47 +-------
include/linux/entry-kvm.h | 2 +-
include/linux/posix-timers.h | 1 -
include/linux/ptrace.h | 81 ++++++++++++-
include/linux/resume_user_mode.h | 64 ++++++++++
include/linux/sched/signal.h | 17 +++
include/linux/task_work.h | 5 +
include/linux/tracehook.h | 226 -----------------------------------
include/uapi/linux/ptrace.h | 2 +-
kernel/entry/common.c | 19 +--
kernel/entry/kvm.c | 9 +-
kernel/exit.c | 3 +-
kernel/livepatch/transition.c | 1 -
kernel/ptrace.c | 47 +++++---
kernel/seccomp.c | 1 -
kernel/signal.c | 62 +++++-----
kernel/task_work.c | 4 +-
kernel/time/posix-cpu-timers.c | 1 +
mm/memcontrol.c | 2 +-
security/apparmor/domain.c | 1 -
security/selinux/hooks.c | 1 -
85 files changed, 372 insertions(+), 495 deletions(-)
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Merge tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull ptrace cleanups from Eric Biederman:
"This set of changes removes tracehook.h, moves modification of all of
the ptrace fields inside of siglock to remove races, adds a missing
permission check to ptrace.c
The removal of tracehook.h is quite significant as it has been a major
source of confusion in recent years. Much of that confusion was around
task_work and TIF_NOTIFY_SIGNAL (which I have now decoupled making the
semantics clearer).
For people who don't know tracehook.h is a vestiage of an attempt to
implement uprobes like functionality that was never fully merged, and
was later superseeded by uprobes when uprobes was merged. For many
years now we have been removing what tracehook functionaly a little
bit at a time. To the point where anything left in tracehook.h was
some weird strange thing that was difficult to understand"
* tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
ptrace: Remove duplicated include in ptrace.c
ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE
ptrace: Return the signal to continue with from ptrace_stop
ptrace: Move setting/clearing ptrace_message into ptrace_stop
tracehook: Remove tracehook.h
resume_user_mode: Move to resume_user_mode.h
resume_user_mode: Remove #ifdef TIF_NOTIFY_RESUME in set_notify_resume
signal: Move set_notify_signal and clear_notify_signal into sched/signal.h
task_work: Decouple TIF_NOTIFY_SIGNAL and task_work
task_work: Call tracehook_notify_signal from get_signal on all architectures
task_work: Introduce task_work_pending
task_work: Remove unnecessary include from posix_timers.h
ptrace: Remove tracehook_signal_handler
ptrace: Remove arch_syscall_{enter,exit}_tracehook
ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h
ptrace/arm: Rename tracehook_report_syscall report_syscall
ptrace: Move ptrace_report_syscall into ptrace.h
It's not a standard approach that use __get_free_page() to alloc path
buffer directly. We'd better use kmalloc and PATH_MAX.
PAGE_SIZE is different on different archs. An unlinked file
with very long canonical pathname will readlink differently
because "(deleted)" eats into a buffer. --adobriyan
[akpm@linux-foundation.org: remove now-unneeded cast]
Link: https://lkml.kernel.org/r/Ye1fCxyZZ0I5lgOL@localhost.localdomain
Signed-off-by: Hao Lee <haolee.swjtu@gmail.com>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now that all of the definitions have moved out of tracehook.h into
ptrace.h, sched/signal.h, resume_user_mode.h there is nothing left in
tracehook.h so remove it.
Update the few files that were depending upon tracehook.h to bring in
definitions to use the headers they need directly.
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20220309162454.123006-13-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Convert return type of proc_fd_access_allowed() and the 'allowed' in it
to be boolean since the return type of ptrace_may_access() is boolean.
Link: https://lkml.kernel.org/r/20211219024404.29779-1-zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge more updates from Andrew Morton:
"87 patches.
Subsystems affected by this patch series: mm (pagecache and hugetlb),
procfs, misc, MAINTAINERS, lib, checkpatch, binfmt, kallsyms, ramfs,
init, codafs, nilfs2, hfs, crash_dump, signals, seq_file, fork,
sysvfs, kcov, gdb, resource, selftests, and ipc"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (87 commits)
ipc/ipc_sysctl.c: remove fallback for !CONFIG_PROC_SYSCTL
ipc: check checkpoint_restore_ns_capable() to modify C/R proc files
selftests/kselftest/runner/run_one(): allow running non-executable files
virtio-mem: disallow mapping virtio-mem memory via /dev/mem
kernel/resource: disallow access to exclusive system RAM regions
kernel/resource: clean up and optimize iomem_is_exclusive()
scripts/gdb: handle split debug for vmlinux
kcov: replace local_irq_save() with a local_lock_t
kcov: avoid enable+disable interrupts if !in_task()
kcov: allocate per-CPU memory on the relevant node
Documentation/kcov: define `ip' in the example
Documentation/kcov: include types.h in the example
sysv: use BUILD_BUG_ON instead of runtime check
kernel/fork.c: unshare(): use swap() to make code cleaner
seq_file: fix passing wrong private data
seq_file: move seq_escape() to a header
signal: remove duplicate include in signal.h
crash_dump: remove duplicate include in crash_dump.h
crash_dump: fix boolreturn.cocci warning
hfs/hfsplus: use WARN_ON for sanity check
...
Problem Description:
When running running ~128 parallel instances of
TZ=/etc/localtime ps -fe >/dev/null
on a 128CPU machine, the %sys utilization reaches 97%, and perf shows
the following code path as being responsible for heavy contention on the
d_lockref spinlock:
walk_component()
lookup_fast()
d_revalidate()
pid_revalidate() // returns -ECHILD
unlazy_child()
lockref_get_not_dead(&nd->path.dentry->d_lockref) <-- contention
The reason is that pid_revalidate() is triggering a drop from RCU to ref
path walk mode. All concurrent path lookups thus try to grab a
reference to the dentry for /proc/, before re-executing pid_revalidate()
and then stepping into the /proc/$pid directory. Thus there is huge
spinlock contention.
This patch allows pid_revalidate() to execute in RCU mode, meaning that
the path lookup can successfully enter the /proc/$pid directory while
still in RCU mode. Later on, the path lookup may still drop into ref
mode, but the contention will be much reduced at this point.
By applying this patch, %sys utilization falls to around 85% under the
same workload, and the number of ps processes executed per unit time
increases by 3x-4x. Although this particular workload is a bit
contrived, we have seen some large collections of eager monitoring
scripts which produced similarly high %sys time due to contention in the
/proc directory.
As a result this patch, Al noted that several procfs methods which were
only called in ref-walk mode could now be called from RCU mode. To
ensure that this patch is safe, I audited all the inode get_link and
permission() implementations, as well as dentry d_revalidate()
implementations, in fs/proc. The purpose here is to ensure that they
either are safe to call in RCU (i.e. don't sleep) or correctly bail out
of RCU mode if they don't support it. My analysis shows that all
at-risk procfs methods are safe to call under RCU, and thus this patch
is safe.
Procfs RCU-walk Analysis:
This analysis is up-to-date with 5.15-rc3. When called under RCU mode,
these functions have arguments as follows:
* get_link() receives a NULL dentry pointer when called in RCU mode.
* permission() receives MAY_NOT_BLOCK in the mode parameter when called
from RCU.
* d_revalidate() receives LOOKUP_RCU in flags.
For the following functions, either they are trivially RCU safe, or they
explicitly bail at the beginning of the function when they run:
proc_ns_get_link (bails out)
proc_get_link (RCU safe)
proc_pid_get_link (bails out)
map_files_d_revalidate (bails out)
map_misc_d_revalidate (bails out)
proc_net_d_revalidate (RCU safe)
proc_sys_revalidate (bails out, also not under /proc/$pid)
tid_fd_revalidate (bails out)
proc_sys_permission (not under /proc/$pid)
The remainder of the functions require a bit more detail:
* proc_fd_permission: RCU safe. All of the body of this function is
under rcu_read_lock(), except generic_permission() which declares
itself RCU safe in its documentation string.
* proc_self_get_link uses GFP_ATOMIC in the RCU case, so it is RCU aware
and otherwise looks safe. The same is true of proc_thread_self_get_link.
* proc_map_files_get_link: calls ns_capable, which calls capable(), and
thus calls into the audit code (see note #1 below). The remainder is
just a call to the trivially safe proc_pid_get_link().
* proc_pid_permission: calls ptrace_may_access(), which appears RCU
safe, although it does call into the "security_ptrace_access_check()"
hook, which looks safe under smack and selinux. Just the audit code is
of concern. Also uses get_task_struct() and put_task_struct(), see
note #2 below.
* proc_tid_comm_permission: Appears safe, though calls put_task_struct
(see note #2 below).
Note #1:
Most of the concern of RCU safety has centered around the audit code.
However, since b17ec22fb3 ("selinux: slow_avc_audit has become
non-blocking"), it's safe to call this code under RCU. So all of the
above are safe by my estimation.
Note #2: get_task_struct() and put_task_struct():
The majority of get_task_struct() is under RCU read lock, and in any
case it is a simple increment. But put_task_struct() is complex, given
that it could at some point free the task struct, and this process has
many steps which I couldn't manually verify. However, several other
places call put_task_struct() under RCU, so it appears safe to use
here too (see kernel/hung_task.c:165 or rcu/tree-stall.h:296)
Patch description:
pid_revalidate() drops from RCU into REF lookup mode. When many threads
are resolving paths within /proc in parallel, this can result in heavy
spinlock contention on d_lockref as each thread tries to grab a
reference to the /proc dentry (and drop it shortly thereafter).
Investigation indicates that it is not necessary to drop RCU in
pid_revalidate(), as no RCU data is modified and the function never
sleeps. So, remove the LOOKUP_RCU check.
Link: https://lkml.kernel.org/r/20211004175629.292270-2-stephen.s.brennan@oracle.com
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Cc: Konrad Wilk <konrad.wilk@oracle.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit 152c432b12.
When a kernel address couldn't be symbolized for /proc/$pid/wchan, it
would leak the raw value, a potential information exposure. This is a
regression compared to the safer pre-v5.12 behavior.
Reported-by: kernel test robot <oliver.sang@intel.com>
Reported-by: Vito Caputo <vcaputo@pengaru.com>
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20211008111626.090829198@infradead.org
While comm change event via prctl has been reported to proc connector by
'commit f786ecba41 ("connector: add comm change event report to proc
connector")', connector listeners were missing comm changes by explicit
writes on /proc/[pid]/comm.
Let explicit writes on /proc/[pid]/comm report to proc connector.
Link: https://lkml.kernel.org/r/20210701133458epcms1p68e9eb9bd0eee8903ba26679a37d9d960@epcms1p6
Signed-off-by: Ohhoon Kwon <ohoono.kwon@samsung.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Android captures per-process system memory state when certain low memory
events (e.g a foreground app kill) occur, to identify potential memory
hoggers. In order to measure how much memory a process actually consumes,
it is necessary to include the DMA buffer sizes for that process in the
memory accounting. Since the handle to DMA buffers are raw FDs, it is
important to be able to identify which processes have FD references to a
DMA buffer.
Currently, DMA buffer FDs can be accounted using /proc/<pid>/fd/* and
/proc/<pid>/fdinfo -- both are only readable by the process owner, as
follows:
1. Do a readlink on each FD.
2. If the target path begins with "/dmabuf", then the FD is a dmabuf FD.
3. stat the file to get the dmabuf inode number.
4. Read/ proc/<pid>/fdinfo/<fd>, to get the DMA buffer size.
Accessing other processes' fdinfo requires root privileges. This limits
the use of the interface to debugging environments and is not suitable for
production builds. Granting root privileges even to a system process
increases the attack surface and is highly undesirable.
Since fdinfo doesn't permit reading process memory and manipulating
process state, allow accessing fdinfo under PTRACE_MODE_READ_FSCRED.
Link: https://lkml.kernel.org/r/20210308170651.919148-1-kaleshsingh@google.com
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Suggested-by: Jann Horn <jannh@google.com>
Acked-by: Christian König <christian.koenig@amd.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Alexey Gladkov <gladkov.alexey@gmail.com>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hridya Valsaraju <hridya@google.com>
Cc: James Morris <jamorris@linux.microsoft.com>
Cc: Jeff Vander Stoep <jeffv@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Szabolcs Nagy <szabolcs.nagy@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use size_t when capping the count argument received by mem_rw(). Since
count is size_t, using min_t(int, ...) can lead to a negative value
that will later be passed to access_remote_vm(), which can cause
unexpected behavior.
Since we are capping the value to at maximum PAGE_SIZE, the conversion
from size_t to int when passing it to access_remote_vm() as "len"
shouldn't be a problem.
Link: https://lkml.kernel.org/r/20210512125215.3348316-1-marcelo.cerri@canonical.com
Reviewed-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Souza Cascardo <cascardo@canonical.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 591a22c14d ("proc: Track /proc/$pid/attr/ opener mm_struct") we
started using __mem_open() to track the mm_struct at open-time, so that
we could then check it for writes.
But that also ended up making the permission checks at open time much
stricter - and not just for writes, but for reads too. And that in turn
caused a regression for at least Fedora 29, where NIC interfaces fail to
start when using NetworkManager.
Since only the write side wanted the mm_struct test, ignore any failures
by __mem_open() at open time, leaving reads unaffected. The write()
time verification of the mm_struct pointer will then catch the failure
case because a NULL pointer will not match a valid 'current->mm'.
Link: https://lore.kernel.org/netdev/YMjTlp2FSJYvoyFa@unreal/
Fixes: 591a22c14d ("proc: Track /proc/$pid/attr/ opener mm_struct")
Reported-and-tested-by: Leon Romanovsky <leon@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit bfb819ea20 ("proc: Check /proc/$pid/attr/ writes against file opener")
tried to make sure that there could not be a confusion between the opener of
a /proc/$pid/attr/ file and the writer. It used struct cred to make sure
the privileges didn't change. However, there were existing cases where a more
privileged thread was passing the opened fd to a differently privileged thread
(during container setup). Instead, use mm_struct to track whether the opener
and writer are still the same process. (This is what several other proc files
already do, though for different reasons.)
Reported-by: Christian Brauner <christian.brauner@ubuntu.com>
Reported-by: Andrea Righi <andrea.righi@canonical.com>
Tested-by: Andrea Righi <andrea.righi@canonical.com>
Fixes: bfb819ea20 ("proc: Check /proc/$pid/attr/ writes against file opener")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix another "confused deputy" weakness[1]. Writes to /proc/$pid/attr/
files need to check the opener credentials, since these fds do not
transition state across execve(). Without this, it is possible to
trick another process (which may have different credentials) to write
to its own /proc/$pid/attr/ files, leading to unexpected and possibly
exploitable behaviors.
[1] https://www.kernel.org/doc/html/latest/security/credentials.html?highlight=confused#open-file-credentials
Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
To resolve the symbol fuction name for wchan, use the printk format
specifier %ps instead of manually looking up the symbol function name
via lookup_symbol_name().
Link: https://lkml.kernel.org/r/20201217165413.GA1959@ls3530.fritz.box
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.
As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.
Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
The generic_fillattr() helper fills in the basic attributes associated
with an inode. Enable it to handle idmapped mounts. If the inode is
accessed through an idmapped mount map it into the mount's user
namespace before we store the uid and gid. If the initial user namespace
is passed nothing changes so non-idmapped mounts will see identical
behavior as before.
Link: https://lore.kernel.org/r/20210121131959.646623-12-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
When file attributes are changed most filesystems rely on the
setattr_prepare(), setattr_copy(), and notify_change() helpers for
initialization and permission checking. Let them handle idmapped mounts.
If the inode is accessed through an idmapped mount map it into the
mount's user namespace. Afterwards the checks are identical to
non-idmapped mounts. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.
Helpers that perform checks on the ia_uid and ia_gid fields in struct
iattr assume that ia_uid and ia_gid are intended values and have already
been mapped correctly at the userspace-kernelspace boundary as we
already do today. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.
Link: https://lore.kernel.org/r/20210121131959.646623-8-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
The two helpers inode_permission() and generic_permission() are used by
the vfs to perform basic permission checking by verifying that the
caller is privileged over an inode. In order to handle idmapped mounts
we extend the two helpers with an additional user namespace argument.
On idmapped mounts the two helpers will make sure to map the inode
according to the mount's user namespace and then peform identical
permission checks to inode_permission() and generic_permission(). If the
initial user namespace is passed nothing changes so non-idmapped mounts
will see identical behavior as before.
Link: https://lore.kernel.org/r/20210121131959.646623-6-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Merge yet more updates from Andrew Morton:
- lots of little subsystems
- a few post-linux-next MM material. Most of the rest awaits more
merging of other trees.
Subsystems affected by this series: alpha, procfs, misc, core-kernel,
bitmap, lib, lz4, checkpatch, nilfs, kdump, rapidio, gcov, bfs, relay,
resource, ubsan, reboot, fault-injection, lzo, apparmor, and mm (swap,
memory-hotplug, pagemap, cleanups, and gup).
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (86 commits)
mm: fix some spelling mistakes in comments
mm: simplify follow_pte{,pmd}
mm: unexport follow_pte_pmd
apparmor: remove duplicate macro list_entry_is_head()
lib/lzo/lzo1x_compress.c: make lzogeneric1x_1_compress() static
fault-injection: handle EI_ETYPE_TRUE
reboot: hide from sysfs not applicable settings
reboot: allow to override reboot type if quirks are found
reboot: remove cf9_safe from allowed types and rename cf9_force
reboot: allow to specify reboot mode via sysfs
reboot: refactor and comment the cpu selection code
lib/ubsan.c: mark type_check_kinds with static keyword
kcov: don't instrument with UBSAN
ubsan: expand tests and reporting
ubsan: remove UBSAN_MISC in favor of individual options
ubsan: enable for all*config builds
ubsan: disable UBSAN_TRAP for all*config
ubsan: disable object-size sanitizer under GCC
ubsan: move cc-option tests into Kconfig
ubsan: remove redundant -Wno-maybe-uninitialized
...
Delete repeated words in fs/proc/.
{the, which}
where "which which" was changed to "with which".
Link: https://lkml.kernel.org/r/20201028191525.13413-1-rdunlap@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Recently syzbot reported[0] that there is a deadlock amongst the users
of exec_update_mutex. The problematic lock ordering found by lockdep
was:
perf_event_open (exec_update_mutex -> ovl_i_mutex)
chown (ovl_i_mutex -> sb_writes)
sendfile (sb_writes -> p->lock)
by reading from a proc file and writing to overlayfs
proc_pid_syscall (p->lock -> exec_update_mutex)
While looking at possible solutions it occured to me that all of the
users and possible users involved only wanted to state of the given
process to remain the same. They are all readers. The only writer is
exec.
There is no reason for readers to block on each other. So fix
this deadlock by transforming exec_update_mutex into a rw_semaphore
named exec_update_lock that only exec takes for writing.
Cc: Jann Horn <jannh@google.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Christopher Yeoh <cyeoh@au1.ibm.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Sargun Dhillon <sargun@sargun.me>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Fixes: eea9673250 ("exec: Add exec_update_mutex to replace cred_guard_mutex")
[0] https://lkml.kernel.org/r/00000000000063640c05ade8e3de@google.com
Reported-by: syzbot+db9cdf3dd1f64252c6ef@syzkaller.appspotmail.com
Link: https://lkml.kernel.org/r/87ft4mbqen.fsf@x220.int.ebiederm.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Currently the kernel does not provide an infrastructure to translate
architecture numbers to a human-readable name. Translating syscall
numbers to syscall names is possible through FTRACE_SYSCALL
infrastructure but it does not provide support for compat syscalls.
This will create a file for each PID as /proc/pid/seccomp_cache.
The file will be empty when no seccomp filters are loaded, or be
in the format of:
<arch name> <decimal syscall number> <ALLOW | FILTER>
where ALLOW means the cache is guaranteed to allow the syscall,
and filter means the cache will pass the syscall to the BPF filter.
For the docker default profile on x86_64 it looks like:
x86_64 0 ALLOW
x86_64 1 ALLOW
x86_64 2 ALLOW
x86_64 3 ALLOW
[...]
x86_64 132 ALLOW
x86_64 133 ALLOW
x86_64 134 FILTER
x86_64 135 FILTER
x86_64 136 FILTER
x86_64 137 ALLOW
x86_64 138 ALLOW
x86_64 139 FILTER
x86_64 140 ALLOW
x86_64 141 ALLOW
[...]
This file is guarded by CONFIG_SECCOMP_CACHE_DEBUG with a default
of N because I think certain users of seccomp might not want the
application to know which syscalls are definitely usable. For
the same reason, it is also guarded by CAP_SYS_ADMIN.
Suggested-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/lkml/CAG48ez3Ofqp4crXGksLmZY6=fGrF_tWyUCg7PBkAetvbbOPeOA@mail.gmail.com/
Signed-off-by: YiFei Zhu <yifeifz2@illinois.edu>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/94e663fa53136f5a11f432c661794d1ee7060779.1605101222.git.yifeifz2@illinois.edu
For oom_score_adj values in the range [942,999], the current
calculations will print 16 for oom_adj. This patch simply limits the
output so output is inline with docs.
Signed-off-by: Charles Haithcock <chaithco@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Link: https://lkml.kernel.org/r/20201020165130.33927-1-chaithco@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make sure the async io-wq workers inherit the loginuid and sessionid from
the original task, and restore them to unset once we're done with the
async work item.
While at it, disable the ability for kernel threads to write to their own
loginuid.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Currently __set_oom_adj loops through all processes in the system to keep
oom_score_adj and oom_score_adj_min in sync between processes sharing
their mm. This is done for any task with more that one mm_users, which
includes processes with multiple threads (sharing mm and signals).
However for such processes the loop is unnecessary because their signal
structure is shared as well.
Android updates oom_score_adj whenever a tasks changes its role
(background/foreground/...) or binds to/unbinds from a service, making it
more/less important. Such operation can happen frequently. We noticed
that updates to oom_score_adj became more expensive and after further
investigation found out that the patch mentioned in "Fixes" introduced a
regression. Using Pixel 4 with a typical Android workload, write time to
oom_score_adj increased from ~3.57us to ~362us. Moreover this regression
linearly depends on the number of multi-threaded processes running on the
system.
Mark the mm with a new MMF_MULTIPROCESS flag bit when task is created with
(CLONE_VM && !CLONE_THREAD && !CLONE_VFORK). Change __set_oom_adj to use
MMF_MULTIPROCESS instead of mm_users to decide whether oom_score_adj
update should be synchronized between multiple processes. To prevent
races between clone() and __set_oom_adj(), when oom_score_adj of the
process being cloned might be modified from userspace, we use
oom_adj_mutex. Its scope is changed to global.
The combination of (CLONE_VM && !CLONE_THREAD) is rarely used except for
the case of vfork(). To prevent performance regressions of vfork(), we
skip taking oom_adj_mutex and setting MMF_MULTIPROCESS when CLONE_VFORK is
specified. Clearing the MMF_MULTIPROCESS flag (when the last process
sharing the mm exits) is left out of this patch to keep it simple and
because it is believed that this threading model is rare. Should there
ever be a need for optimizing that case as well, it can be done by hooking
into the exit path, likely following the mm_update_next_owner pattern.
With the combination of (CLONE_VM && !CLONE_THREAD && !CLONE_VFORK) being
quite rare, the regression is gone after the change is applied.
[surenb@google.com: v3]
Link: https://lkml.kernel.org/r/20200902012558.2335613-1-surenb@google.com
Fixes: 44a70adec9 ("mm, oom_adj: make sure processes sharing mm have same view of oom_score_adj")
Reported-by: Tim Murray <timmurray@google.com>
Suggested-by: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Eugene Syromiatnikov <esyr@redhat.com>
Cc: Christian Kellner <christian@kellner.me>
Cc: Adrian Reber <areber@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Gladkov <gladkov.alexey@gmail.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc: John Johansen <john.johansen@canonical.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Link: https://lkml.kernel.org/r/20200824153036.3201505-1-surenb@google.com
Debugged-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Recently we found an issue on our production environment that when memcg
oom is triggered the oom killer doesn't chose the process with largest
resident memory but chose the first scanned process. Note that all
processes in this memcg have the same oom_score_adj, so the oom killer
should chose the process with largest resident memory.
Bellow is part of the oom info, which is enough to analyze this issue.
[7516987.983223] memory: usage 16777216kB, limit 16777216kB, failcnt 52843037
[7516987.983224] memory+swap: usage 16777216kB, limit 9007199254740988kB, failcnt 0
[7516987.983225] kmem: usage 301464kB, limit 9007199254740988kB, failcnt 0
[...]
[7516987.983293] [ pid ] uid tgid total_vm rss pgtables_bytes swapents oom_score_adj name
[7516987.983510] [ 5740] 0 5740 257 1 32768 0 -998 pause
[7516987.983574] [58804] 0 58804 4594 771 81920 0 -998 entry_point.bas
[7516987.983577] [58908] 0 58908 7089 689 98304 0 -998 cron
[7516987.983580] [58910] 0 58910 16235 5576 163840 0 -998 supervisord
[7516987.983590] [59620] 0 59620 18074 1395 188416 0 -998 sshd
[7516987.983594] [59622] 0 59622 18680 6679 188416 0 -998 python
[7516987.983598] [59624] 0 59624 1859266 5161 548864 0 -998 odin-agent
[7516987.983600] [59625] 0 59625 707223 9248 983040 0 -998 filebeat
[7516987.983604] [59627] 0 59627 416433 64239 774144 0 -998 odin-log-agent
[7516987.983607] [59631] 0 59631 180671 15012 385024 0 -998 python3
[7516987.983612] [61396] 0 61396 791287 3189 352256 0 -998 client
[7516987.983615] [61641] 0 61641 1844642 29089 946176 0 -998 client
[7516987.983765] [ 9236] 0 9236 2642 467 53248 0 -998 php_scanner
[7516987.983911] [42898] 0 42898 15543 838 167936 0 -998 su
[7516987.983915] [42900] 1000 42900 3673 867 77824 0 -998 exec_script_vr2
[7516987.983918] [42925] 1000 42925 36475 19033 335872 0 -998 python
[7516987.983921] [57146] 1000 57146 3673 848 73728 0 -998 exec_script_J2p
[7516987.983925] [57195] 1000 57195 186359 22958 491520 0 -998 python2
[7516987.983928] [58376] 1000 58376 275764 14402 290816 0 -998 rosmaster
[7516987.983931] [58395] 1000 58395 155166 4449 245760 0 -998 rosout
[7516987.983935] [58406] 1000 58406 18285584 3967322 37101568 0 -998 data_sim
[7516987.984221] oom-kill:constraint=CONSTRAINT_MEMCG,nodemask=(null),cpuset=3aa16c9482ae3a6f6b78bda68a55d32c87c99b985e0f11331cddf05af6c4d753,mems_allowed=0-1,oom_memcg=/kubepods/podf1c273d3-9b36-11ea-b3df-246e9693c184,task_memcg=/kubepods/podf1c273d3-9b36-11ea-b3df-246e9693c184/1f246a3eeea8f70bf91141eeaf1805346a666e225f823906485ea0b6c37dfc3d,task=pause,pid=5740,uid=0
[7516987.984254] Memory cgroup out of memory: Killed process 5740 (pause) total-vm:1028kB, anon-rss:4kB, file-rss:0kB, shmem-rss:0kB
[7516988.092344] oom_reaper: reaped process 5740 (pause), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
We can find that the first scanned process 5740 (pause) was killed, but
its rss is only one page. That is because, when we calculate the oom
badness in oom_badness(), we always ignore the negtive point and convert
all of these negtive points to 1. Now as oom_score_adj of all the
processes in this targeted memcg have the same value -998, the points of
these processes are all negtive value. As a result, the first scanned
process will be killed.
The oom_socre_adj (-998) in this memcg is set by kubelet, because it is a
a Guaranteed pod, which has higher priority to prevent from being killed
by system oom.
To fix this issue, we should make the calculation of oom point more
accurate. We can achieve it by convert the chosen_point from 'unsigned
long' to 'long'.
[cai@lca.pw: reported a issue in the previous version]
[mhocko@suse.com: fixed the issue reported by Cai]
[mhocko@suse.com: add the comment in proc_oom_score()]
[laoar.shao@gmail.com: v3]
Link: http://lkml.kernel.org/r/1594396651-9931-1-git-send-email-laoar.shao@gmail.com
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Qian Cai <cai@lca.pw>
Link: http://lkml.kernel.org/r/1594309987-9919-1-git-send-email-laoar.shao@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Opening files in /proc/pid/map_files when the current user is
CAP_CHECKPOINT_RESTORE capable in the root namespace is useful for
checkpointing and restoring to recover files that are unreachable via
the file system such as deleted files, or memfd files.
Signed-off-by: Adrian Reber <areber@redhat.com>
Signed-off-by: Nicolas Viennot <Nicolas.Viennot@twosigma.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Link: https://lore.kernel.org/r/20200719100418.2112740-5-areber@redhat.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Convert the last few remaining mmap_sem rwsem calls to use the new mmap
locking API. These were missed by coccinelle for some reason (I think
coccinelle does not support some of the preprocessor constructs in these
files ?)
[akpm@linux-foundation.org: convert linux-next leftovers]
[akpm@linux-foundation.org: more linux-next leftovers]
[akpm@linux-foundation.org: more linux-next leftovers]
Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ying Han <yinghan@google.com>
Link: http://lkml.kernel.org/r/20200520052908.204642-6-walken@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+ Features
- Replace zero-length array with flexible-array
- add a valid state flags check
- add consistency check between state and dfa diff encode flags
- add apparmor subdir to proc attr interface
- fail unpack if profile mode is unknown
- add outofband transition and use it in xattr match
- ensure that dfa state tables have entries
+ Cleanups
- Use true and false for bool variable
- Remove semicolon
- Clean code by removing redundant instructions
- Replace two seq_printf() calls by seq_puts() in aa_label_seq_xprint()
- remove duplicate check of xattrs on profile attachment
- remove useless aafs_create_symlink
+ Bug fixes
- Fix memory leak of profile proxy
- fix introspection of of task mode for unconfined tasks
- fix nnp subset test for unconfined
- check/put label on apparmor_sk_clone_security()
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Merge tag 'apparmor-pr-2020-06-07' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor
Pull apparmor updates from John Johansen:
"Features:
- Replace zero-length array with flexible-array
- add a valid state flags check
- add consistency check between state and dfa diff encode flags
- add apparmor subdir to proc attr interface
- fail unpack if profile mode is unknown
- add outofband transition and use it in xattr match
- ensure that dfa state tables have entries
Cleanups:
- Use true and false for bool variable
- Remove semicolon
- Clean code by removing redundant instructions
- Replace two seq_printf() calls by seq_puts() in aa_label_seq_xprint()
- remove duplicate check of xattrs on profile attachment
- remove useless aafs_create_symlink
Bug fixes:
- Fix memory leak of profile proxy
- fix introspection of of task mode for unconfined tasks
- fix nnp subset test for unconfined
- check/put label on apparmor_sk_clone_security()"
* tag 'apparmor-pr-2020-06-07' of git://git.kernel.org/pub/scm/linux/kernel/git/jj/linux-apparmor:
apparmor: Fix memory leak of profile proxy
apparmor: fix introspection of of task mode for unconfined tasks
apparmor: check/put label on apparmor_sk_clone_security()
apparmor: Use true and false for bool variable
security/apparmor/label.c: Clean code by removing redundant instructions
apparmor: Replace zero-length array with flexible-array
apparmor: ensure that dfa state tables have entries
apparmor: remove duplicate check of xattrs on profile attachment.
apparmor: add outofband transition and use it in xattr match
apparmor: fail unpack if profile mode is unknown
apparmor: fix nnp subset test for unconfined
apparmor: remove useless aafs_create_symlink
apparmor: add proc subdir to attrs
apparmor: add consistency check between state and dfa diff encode flags
apparmor: add a valid state flags check
AppArmor: Remove semicolon
apparmor: Replace two seq_printf() calls by seq_puts() in aa_label_seq_xprint()
Pull proc updates from Eric Biederman:
"This has four sets of changes:
- modernize proc to support multiple private instances
- ensure we see the exit of each process tid exactly
- remove has_group_leader_pid
- use pids not tasks in posix-cpu-timers lookup
Alexey updated proc so each mount of proc uses a new superblock. This
allows people to actually use mount options with proc with no fear of
messing up another mount of proc. Given the kernel's internal mounts
of proc for things like uml this was a real problem, and resulted in
Android's hidepid mount options being ignored and introducing security
issues.
The rest of the changes are small cleanups and fixes that came out of
my work to allow this change to proc. In essence it is swapping the
pids in de_thread during exec which removes a special case the code
had to handle. Then updating the code to stop handling that special
case"
* 'proc-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
proc: proc_pid_ns takes super_block as an argument
remove the no longer needed pid_alive() check in __task_pid_nr_ns()
posix-cpu-timers: Replace __get_task_for_clock with pid_for_clock
posix-cpu-timers: Replace cpu_timer_pid_type with clock_pid_type
posix-cpu-timers: Extend rcu_read_lock removing task_struct references
signal: Remove has_group_leader_pid
exec: Remove BUG_ON(has_group_leader_pid)
posix-cpu-timer: Unify the now redundant code in lookup_task
posix-cpu-timer: Tidy up group_leader logic in lookup_task
proc: Ensure we see the exit of each process tid exactly once
rculist: Add hlists_swap_heads_rcu
proc: Use PIDTYPE_TGID in next_tgid
Use proc_pid_ns() to get pid_namespace from the proc superblock
proc: use named enums for better readability
proc: use human-readable values for hidepid
docs: proc: add documentation for "hidepid=4" and "subset=pid" options and new mount behavior
proc: add option to mount only a pids subset
proc: instantiate only pids that we can ptrace on 'hidepid=4' mount option
proc: allow to mount many instances of proc in one pid namespace
proc: rename struct proc_fs_info to proc_fs_opts
syzbot found that
touch /proc/testfile
causes NULL pointer dereference at tomoyo_get_local_path()
because inode of the dentry is NULL.
Before c59f415a7c, Tomoyo received pid_ns from proc's s_fs_info
directly. Since proc_pid_ns() can only work with inode, using it in
the tomoyo_get_local_path() was wrong.
To avoid creating more functions for getting proc_ns, change the
argument type of the proc_pid_ns() function. Then, Tomoyo can use
the existing super_block to get pid_ns.
Link: https://lkml.kernel.org/r/0000000000002f0c7505a5b0e04c@google.com
Link: https://lkml.kernel.org/r/20200518180738.2939611-1-gladkov.alexey@gmail.com
Reported-by: syzbot+c1af344512918c61362c@syzkaller.appspotmail.com
Fixes: c59f415a7c ("Use proc_pid_ns() to get pid_namespace from the proc superblock")
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Pull pid leak fix from Eric Biederman:
"Oleg noticed that put_pid(thread_pid) was not getting called when proc
was not compiled in.
Let's get that fixed before 5.7 is released and causes problems for
anyone"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
proc: Put thread_pid in release_task not proc_flush_pid
Combine the pid_task and thes test has_group_leader_pid into a single
dereference by using pid_task(PIDTYPE_TGID).
This makes the code simpler and proof against needing to even think
about any shenanigans that de_thread might get up to.
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Alexey Gladkov <gladkov.alexey@gmail.com> writes:
Procfs modernization:
---------------------
Historically procfs was always tied to pid namespaces, during pid
namespace creation we internally create a procfs mount for it. However,
this has the effect that all new procfs mounts are just a mirror of the
internal one, any change, any mount option update, any new future
introduction will propagate to all other procfs mounts that are in the
same pid namespace.
This may have solved several use cases in that time. However today we
face new requirements, and making procfs able to support new private
instances inside same pid namespace seems a major point. If we want to
to introduce new features and security mechanisms we have to make sure
first that we do not break existing usecases. Supporting private procfs
instances will allow to support new features and behaviour without
propagating it to all other procfs mounts.
Today procfs is more of a burden especially to some Embedded, IoT,
sandbox, container use cases. In user space we are over-mounting null
or inaccessible files on top to hide files and information. If we want
to hide pids we have to create PID namespaces otherwise mount options
propagate to all other proc mounts, changing a mount option value in one
mount will propagate to all other proc mounts. If we want to introduce
new features, then they will propagate to all other mounts too, resulting
either maybe new useful functionality or maybe breaking stuff. We have
also to note that userspace should not workaround procfs, the kernel
should just provide a sane simple interface.
In this regard several developers and maintainers pointed out that
there are problems with procfs and it has to be modernized:
"Here's another one: split up and modernize /proc." by Andy Lutomirski [1]
Discussion about kernel pointer leaks:
"And yes, as Kees and Daniel mentioned, it's definitely not just dmesg.
In fact, the primary things tend to be /proc and /sys, not dmesg
itself." By Linus Torvalds [2]
Lot of other areas in the kernel and filesystems have been updated to be
able to support private instances, devpts is one major example [3].
Which will be used for:
1) Embedded systems and IoT: usually we have one supervisor for
apps, we have some lightweight sandbox support, however if we create
pid namespaces we have to manage all the processes inside too,
where our goal is to be able to run a bunch of apps each one inside
its own mount namespace, maybe use network namespaces for vlans
setups, but right now we only want mount namespaces, without all the
other complexity. We want procfs to behave more like a real file system,
and block access to inodes that belong to other users. The 'hidepid=' will
not work since it is a shared mount option.
2) Containers, sandboxes and Private instances of file systems - devpts case
Historically, lot of file systems inside Linux kernel view when instantiated
were just a mirror of an already created and mounted filesystem. This was the
case of devpts filesystem, it seems at that time the requirements were to
optimize things and reuse the same memory, etc. This design used to work but not
anymore with today's containers, IoT, hostile environments and all the privacy
challenges that Linux faces.
In that regards, devpts was updated so that each new mounts is a total
independent file system by the following patches:
"devpts: Make each mount of devpts an independent filesystem" by
Eric W. Biederman [3] [4]
3) Linux Security Modules have multiple ptrace paths inside some
subsystems, however inside procfs, the implementation does not guarantee
that the ptrace() check which triggers the security_ptrace_check() hook
will always run. We have the 'hidepid' mount option that can be used to
force the ptrace_may_access() check inside has_pid_permissions() to run.
The problem is that 'hidepid' is per pid namespace and not attached to
the mount point, any remount or modification of 'hidepid' will propagate
to all other procfs mounts.
This also does not allow to support Yama LSM easily in desktop and user
sessions. Yama ptrace scope which restricts ptrace and some other
syscalls to be allowed only on inferiors, can be updated to have a
per-task context, where the context will be inherited during fork(),
clone() and preserved across execve(). If we support multiple private
procfs instances, then we may force the ptrace_may_access() on
/proc/<pids>/ to always run inside that new procfs instances. This will
allow to specifiy on user sessions if we should populate procfs with
pids that the user can ptrace or not.
By using Yama ptrace scope, some restricted users will only be able to see
inferiors inside /proc, they won't even be able to see their other
processes. Some software like Chromium, Firefox's crash handler, Wine
and others are already using Yama to restrict which processes can be
ptracable. With this change this will give the possibility to restrict
/proc/<pids>/ but more importantly this will give desktop users a
generic and usuable way to specifiy which users should see all processes
and which user can not.
Side notes:
* This covers the lack of seccomp where it is not able to parse
arguments, it is easy to install a seccomp filter on direct syscalls
that operate on pids, however /proc/<pid>/ is a Linux ABI using
filesystem syscalls. With this change all LSMs should be able to analyze
open/read/write/close... on /proc/<pid>/
4) This will allow to implement new features either in kernel or
userspace without having to worry about procfs.
In containers, sandboxes, etc we have workarounds to hide some /proc
inodes, this should be supported natively without doing extra complex
work, the kernel should be able to support sane options that work with
today and future Linux use cases.
5) Creation of new superblock with all procfs options for each procfs
mount will fix the ignoring of mount options. The problem is that the
second mount of procfs in the same pid namespace ignores the mount
options. The mount options are ignored without error until procfs is
remounted.
Before:
proc /proc proc rw,relatime,hidepid=2 0 0
mount("proc", "/tmp/proc", "proc", 0, "hidepid=1") = 0
+++ exited with 0 +++
proc /proc proc rw,relatime,hidepid=2 0 0
proc /tmp/proc proc rw,relatime,hidepid=2 0 0
proc /proc proc rw,relatime,hidepid=1 0 0
proc /tmp/proc proc rw,relatime,hidepid=1 0 0
After:
proc /proc proc rw,relatime,hidepid=ptraceable 0 0
proc /proc proc rw,relatime,hidepid=ptraceable 0 0
proc /tmp/proc proc rw,relatime,hidepid=invisible 0 0
Introduced changes:
-------------------
Each mount of procfs creates a separate procfs instance with its own
mount options.
This series adds few new mount options:
* New 'hidepid=ptraceable' or 'hidepid=4' mount option to show only ptraceable
processes in the procfs. This allows to support lightweight sandboxes in
Embedded Linux, also solves the case for LSM where now with this mount option,
we make sure that they have a ptrace path in procfs.
* 'subset=pid' that allows to hide non-pid inodes from procfs. It can be used
in containers and sandboxes, as these are already trying to hide and block
access to procfs inodes anyway.
ChangeLog:
----------
* Rebase on top of v5.7-rc1.
* Fix a resource leak if proc is not mounted or if proc is simply reconfigured.
* Add few selftests.
* After a discussion with Eric W. Biederman, the numerical values for hidepid
parameter have been removed from uapi.
* Remove proc_self and proc_thread_self from the pid_namespace struct.
* I took into account the comment of Kees Cook.
* Update Reviewed-by tags.
* 'subset=pidfs' renamed to 'subset=pid' as suggested by Alexey Dobriyan.
* Include Reviewed-by tags.
* Rebase on top of Eric W. Biederman's procfs changes.
* Add human readable values of 'hidepid' as suggested by Andy Lutomirski.
* Started using RCU lock to clean dcache entries as suggested by Linus Torvalds.
* 'pidonly=1' renamed to 'subset=pidfs' as suggested by Alexey Dobriyan.
* HIDEPID_* moved to uapi/ as they are user interface to mount().
Suggested-by Alexey Dobriyan <adobriyan@gmail.com>
* 'hidepid=' and 'gid=' mount options are moved from pid namespace to superblock.
* 'newinstance' mount option removed as suggested by Eric W. Biederman.
Mount of procfs always creates a new instance.
* 'limit_pids' renamed to 'hidepid=3'.
* I took into account the comment of Linus Torvalds [7].
* Documentation added.
* Fixed a bug that caused a problem with the Fedora boot.
* The 'pidonly' option is visible among the mount options.
* Renamed mount options to 'newinstance' and 'pids='
Suggested-by: Andy Lutomirski <luto@kernel.org>
* Fixed order of commit, Suggested-by: Andy Lutomirski <luto@kernel.org>
* Many bug fixes.
* Removed 'unshared' mount option and replaced it with 'limit_pids'
which is attached to the current procfs mount.
Suggested-by Andy Lutomirski <luto@kernel.org>
* Do not fill dcache with pid entries that we can not ptrace.
* Many bug fixes.
References:
-----------
[1] https://lists.linuxfoundation.org/pipermail/ksummit-discuss/2017-January/004215.html
[2] http://www.openwall.com/lists/kernel-hardening/2017/10/05/5
[3] https://lwn.net/Articles/689539/
[4] http://lxr.free-electrons.com/source/Documentation/filesystems/devpts.txt?v=3.14
[5] https://lkml.org/lkml/2017/5/2/407
[6] https://lkml.org/lkml/2017/5/3/357
[7] https://lkml.org/lkml/2018/5/11/505
Alexey Gladkov (7):
proc: rename struct proc_fs_info to proc_fs_opts
proc: allow to mount many instances of proc in one pid namespace
proc: instantiate only pids that we can ptrace on 'hidepid=4' mount
option
proc: add option to mount only a pids subset
docs: proc: add documentation for "hidepid=4" and "subset=pid" options
and new mount behavior
proc: use human-readable values for hidepid
proc: use named enums for better readability
Documentation/filesystems/proc.rst | 92 +++++++++---
fs/proc/base.c | 48 +++++--
fs/proc/generic.c | 9 ++
fs/proc/inode.c | 30 +++-
fs/proc/root.c | 131 +++++++++++++-----
fs/proc/self.c | 6 +-
fs/proc/thread_self.c | 6 +-
fs/proc_namespace.c | 14 +-
include/linux/pid_namespace.h | 12 --
include/linux/proc_fs.h | 30 +++-
tools/testing/selftests/proc/.gitignore | 2 +
tools/testing/selftests/proc/Makefile | 2 +
.../selftests/proc/proc-fsconfig-hidepid.c | 50 +++++++
.../selftests/proc/proc-multiple-procfs.c | 48 +++++++
14 files changed, 384 insertions(+), 96 deletions(-)
create mode 100644 tools/testing/selftests/proc/proc-fsconfig-hidepid.c
create mode 100644 tools/testing/selftests/proc/proc-multiple-procfs.c
Link: https://lore.kernel.org/lkml/20200419141057.621356-1-gladkov.alexey@gmail.com/
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Oleg pointed out that in the unlikely event the kernel is compiled
with CONFIG_PROC_FS unset that release_task will now leak the pid.
Move the put_pid out of proc_flush_pid into release_task to fix this
and to guarantee I don't make that mistake again.
When possible it makes sense to keep get and put in the same function
so it can easily been seen how they pair up.
Fixes: 7bc3e6e55a ("proc: Use a list of inodes to flush from proc")
Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
If "hidepid=4" mount option is set then do not instantiate pids that
we can not ptrace. "hidepid=4" means that procfs should only contain
pids that the caller can ptrace.
Signed-off-by: Djalal Harouni <tixxdz@gmail.com>
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
This patch allows to have multiple procfs instances inside the
same pid namespace. The aim here is lightweight sandboxes, and to allow
that we have to modernize procfs internals.
1) The main aim of this work is to have on embedded systems one
supervisor for apps. Right now we have some lightweight sandbox support,
however if we create pid namespacess we have to manages all the
processes inside too, where our goal is to be able to run a bunch of
apps each one inside its own mount namespace without being able to
notice each other. We only want to use mount namespaces, and we want
procfs to behave more like a real mount point.
2) Linux Security Modules have multiple ptrace paths inside some
subsystems, however inside procfs, the implementation does not guarantee
that the ptrace() check which triggers the security_ptrace_check() hook
will always run. We have the 'hidepid' mount option that can be used to
force the ptrace_may_access() check inside has_pid_permissions() to run.
The problem is that 'hidepid' is per pid namespace and not attached to
the mount point, any remount or modification of 'hidepid' will propagate
to all other procfs mounts.
This also does not allow to support Yama LSM easily in desktop and user
sessions. Yama ptrace scope which restricts ptrace and some other
syscalls to be allowed only on inferiors, can be updated to have a
per-task context, where the context will be inherited during fork(),
clone() and preserved across execve(). If we support multiple private
procfs instances, then we may force the ptrace_may_access() on
/proc/<pids>/ to always run inside that new procfs instances. This will
allow to specifiy on user sessions if we should populate procfs with
pids that the user can ptrace or not.
By using Yama ptrace scope, some restricted users will only be able to see
inferiors inside /proc, they won't even be able to see their other
processes. Some software like Chromium, Firefox's crash handler, Wine
and others are already using Yama to restrict which processes can be
ptracable. With this change this will give the possibility to restrict
/proc/<pids>/ but more importantly this will give desktop users a
generic and usuable way to specifiy which users should see all processes
and which users can not.
Side notes:
* This covers the lack of seccomp where it is not able to parse
arguments, it is easy to install a seccomp filter on direct syscalls
that operate on pids, however /proc/<pid>/ is a Linux ABI using
filesystem syscalls. With this change LSMs should be able to analyze
open/read/write/close...
In the new patch set version I removed the 'newinstance' option
as suggested by Eric W. Biederman.
Selftest has been added to verify new behavior.
Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Aleksa Sarai