linux.git/fs/namespace.c, branch v5.15

Merge branch 'akpm' (patches from Andrew)

2021-09-03T17:08:28+00:00

Merge misc updates from Andrew Morton:
 "173 patches.

  Subsystems affected by this series: ia64, ocfs2, block, and mm (debug,
  pagecache, gup, swap, shmem, memcg, selftests, pagemap, mremap,
  bootmem, sparsemem, vmalloc, kasan, pagealloc, memory-failure,
  hugetlb, userfaultfd, vmscan, compaction, mempolicy, memblock,
  oom-kill, migration, ksm, percpu, vmstat, and madvise)"

* emailed patches from Andrew Morton : (173 commits)
  mm/madvise: add MADV_WILLNEED to process_madvise()
  mm/vmstat: remove unneeded return value
  mm/vmstat: simplify the array size calculation
  mm/vmstat: correct some wrong comments
  mm/percpu,c: remove obsolete comments of pcpu_chunk_populated()
  selftests: vm: add COW time test for KSM pages
  selftests: vm: add KSM merging time test
  mm: KSM: fix data type
  selftests: vm: add KSM merging across nodes test
  selftests: vm: add KSM zero page merging test
  selftests: vm: add KSM unmerge test
  selftests: vm: add KSM merge test
  mm/migrate: correct kernel-doc notation
  mm: wire up syscall process_mrelease
  mm: introduce process_mrelease system call
  memblock: make memblock_find_in_range method private
  mm/mempolicy.c: use in_task() in mempolicy_slab_node()
  mm/mempolicy: unify the create() func for bind/interleave/prefer-many policies
  mm/mempolicy: advertise new MPOL_PREFERRED_MANY
  mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY
  ...

memcg: enable accounting for new namesapces and struct nsproxy

2021-09-03T16:58:12+00:00

Container admin can create new namespaces and force kernel to allocate up
to several pages of memory for the namespaces and its associated
structures.

Net and uts namespaces have enabled accounting for such allocations.  It
makes sense to account for rest ones to restrict the host's memory
consumption from inside the memcg-limited container.

Link: https://lkml.kernel.org/r/5525bcbf-533e-da27-79b7-158686c64e13@virtuozzo.com
Signed-off-by: Vasily Averin 
Acked-by: Serge Hallyn 
Acked-by: Christian Brauner 
Acked-by: Kirill Tkhai 
Reviewed-by: Shakeel Butt 
Cc: Alexander Viro 
Cc: Alexey Dobriyan 
Cc: Andrei Vagin 
Cc: Borislav Petkov 
Cc: Borislav Petkov 
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: "Eric W. Biederman" 
Cc: Greg Kroah-Hartman 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: "J. Bruce Fields" 
Cc: Jeff Layton 
Cc: Jens Axboe 
Cc: Jiri Slaby 
Cc: Johannes Weiner 
Cc: Michal Hocko 
Cc: Oleg Nesterov 
Cc: Roman Gushchin 
Cc: Tejun Heo 
Cc: Thomas Gleixner 
Cc: Vladimir Davydov 
Cc: Yutian Yang 
Cc: Zefan Li 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: enable accounting for mnt_cache entries

2021-09-03T16:58:12+00:00

Patch series "memcg accounting from OpenVZ", v7.

OpenVZ uses memory accounting 20+ years since v2.2.x linux kernels.
Initially we used our own accounting subsystem, then partially committed
it to upstream, and a few years ago switched to cgroups v1.  Now we're
rebasing again, revising our old patches and trying to push them upstream.

We try to protect the host system from any misuse of kernel memory
allocation triggered by untrusted users inside the containers.

Patch-set is addressed mostly to cgroups maintainers and cgroups@ mailing
list, though I would be very grateful for any comments from maintainersi
of affected subsystems or other people added in cc:

Compared to the upstream, we additionally account the following kernel objects:
- network devices and its Tx/Rx queues
- ipv4/v6 addresses and routing-related objects
- inet_bind_bucket cache objects
- VLAN group arrays
- ipv6/sit: ip_tunnel_prl
- scm_fp_list objects used by SCM_RIGHTS messages of Unix sockets
- nsproxy and namespace objects itself
- IPC objects: semaphores, message queues and share memory segments
- mounts
- pollfd and select bits arrays
- signals and posix timers
- file lock
- fasync_struct used by the file lease code and driver's fasync queues
- tty objects
- per-mm LDT

We have an incorrect/incomplete/obsoleted accounting for few other kernel
objects: sk_filter, af_packets, netlink and xt_counters for iptables.
They require rework and probably will be dropped at all.

Also we're going to add an accounting for nft, however it is not ready
yet.

We have not tested performance on upstream, however, our performance team
compares our current RHEL7-based production kernel and reports that they
are at least not worse as the according original RHEL7 kernel.

This patch (of 10):

The kernel allocates ~400 bytes of 'struct mount' for any new mount.
Creating a new mount namespace clones most of the parent mounts, and this
can be repeated many times.  Additionally, each mount allocates up to
PATH_MAX=4096 bytes for mnt->mnt_devname.

It makes sense to account for these allocations to restrict the host's
memory consumption from inside the memcg-limited container.

Link: https://lkml.kernel.org/r/045db11f-4a45-7c9b-2664-5b32c2b44943@virtuozzo.com
Signed-off-by: Vasily Averin 
Reviewed-by: Shakeel Butt 
Acked-by: Christian Brauner 
Cc: Tejun Heo 
Cc: Michal Hocko 
Cc: Johannes Weiner 
Cc: Vladimir Davydov 
Cc: Roman Gushchin 
Cc: Yutian Yang 
Cc: Alexander Viro 
Cc: Alexey Dobriyan 
Cc: Andrei Vagin 
Cc: Borislav Petkov 
Cc: Dmitry Safonov <0x7f454c46@gmail.com>
Cc: "Eric W. Biederman" 
Cc: Greg Kroah-Hartman 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: "J. Bruce Fields" 
Cc: Jeff Layton 
Cc: Jens Axboe 
Cc: Jiri Slaby 
Cc: Kirill Tkhai 
Cc: Oleg Nesterov 
Cc: Serge Hallyn 
Cc: Thomas Gleixner 
Cc: Zefan Li 
Cc: Borislav Petkov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'fs.move_mount.move_mount_set_group.v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

2021-08-31T18:54:02+00:00

Pull move_mount updates from Christian Brauner:
 "This contains an extension to the move_mount() syscall making it
  possible to add a single private mount into an existing propagation
  tree.

  The use-case comes from the criu folks which have been struggling with
  restoring complex mount trees for a long time. Variations of this work
  have been discussed at Plumbers before, e.g.

      https://www.linuxplumbersconf.org/event/7/contributions/640/

  The extension to move_mount() enables criu to restore any set of mount
  namespaces, mount trees and sharing group trees without introducing
  yet more complexity into mount propagation itself.

  The changes required to criu to make use of this and restore complex
  propagation trees are available at

      https://github.com/Snorch/criu/commits/mount-v2-poc

  A cleaned-up version of this will go up for merging into the main criu
  repo after this lands"

* tag 'fs.move_mount.move_mount_set_group.v5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  tests: add move_mount(MOVE_MOUNT_SET_GROUP) selftest
  move_mount: allow to add a mount into an existing group

fs: remove mandatory file locking support

2021-08-23T10:15:36+00:00

We added CONFIG_MANDATORY_FILE_LOCKING in 2015, and soon after turned it
off in Fedora and RHEL8. Several other distros have followed suit.

I've heard of one problem in all that time: Someone migrated from an
older distro that supported "-o mand" to one that didn't, and the host
had a fstab entry with "mand" in it which broke on reboot. They didn't
actually _use_ mandatory locking so they just removed the mount option
and moved on.

This patch rips out mandatory locking support wholesale from the kernel,
along with the Kconfig option and the Documentation file. It also
changes the mount code to ignore the "mand" mount option instead of
erroring out, and to throw a big, ugly warning.

Signed-off-by: Jeff Layton

Merge tag 'locks-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux

2021-08-21T17:50:22+00:00

Pull mandatory file locking deprecation warning from Jeff Layton:
 "As discussed on the list, this patch just adds a new warning for folks
  who still have mandatory locking enabled and actually mount with '-o
  mand'. I'd like to get this in for v5.14 so we can push this out into
  stable kernels and hopefully reach folks who have mounts with -o mand.

  For now, I'm operating under the assumption that we'll fully remove
  this support in v5.15, but we can move that out if any legitimate
  users of this facility speak up between now and then"

* tag 'locks-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
  fs: warn about impending deprecation of mandatory locks

fs: warn about impending deprecation of mandatory locks

2021-08-21T11:32:45+00:00

We've had CONFIG_MANDATORY_FILE_LOCKING since 2015 and a lot of distros
have disabled it. Warn the stragglers that still use "-o mand" that
we'll be dropping support for that mount option.

Cc: stable@vger.kernel.org
Signed-off-by: Jeff Layton

ovl: prevent private clone if bind mount is not allowed

2021-08-10T08:21:31+00:00

Add the following checks from __do_loopback() to clone_private_mount() as
well:

 - verify that the mount is in the current namespace

 - verify that there are no locked children

Reported-by: Alois Wohlschlager 
Fixes: c771d683a62e ("vfs: introduce clone_private_mount()")
Cc:  # v3.18
Signed-off-by: Miklos Szeredi

move_mount: allow to add a mount into an existing group

2021-07-26T12:45:18+00:00

Previously a sharing group (shared and master ids pair) can be only
inherited when mount is created via bindmount. This patch adds an
ability to add an existing private mount into an existing sharing group.

With this functionality one can first create the desired mount tree from
only private mounts (without the need to care about undesired mount
propagation or mount creation order implied by sharing group
dependencies), and next then setup any desired mount sharing between
those mounts in tree as needed.

This allows CRIU to restore any set of mount namespaces, mount trees and
sharing group trees for a container.

We have many issues with restoring mounts in CRIU related to sharing
groups and propagation:
- reverse sharing groups vs mount tree order requires complex mounts
  reordering which mostly implies also using some temporary mounts
(please see https://lkml.org/lkml/2021/3/23/569 for more info)

- mount() syscall creates tons of mounts due to propagation
- mount re-parenting due to propagation
- "Mount Trap" due to propagation
- "Non Uniform" propagation, meaning that with different tricks with
  mount order and temporary children-"lock" mounts one can create mount
  trees which can't be restored without those tricks
(see https://www.linuxplumbersconf.org/event/7/contributions/640/)

With this new functionality we can resolve all the problems with
propagation at once.

Link: https://lore.kernel.org/r/20210715100714.120228-1-ptikhomirov@virtuozzo.com
Cc: Eric W. Biederman 
Cc: Alexander Viro 
Cc: Christian Brauner 
Cc: Mattias Nissler 
Cc: Aleksa Sarai 
Cc: Andrei Vagin 
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-api@vger.kernel.org
Cc: lkml 
Co-developed-by: Andrei Vagin 
Acked-by: Christian Brauner 
Signed-off-by: Pavel Tikhomirov 
Signed-off-by: Andrei Vagin 
Signed-off-by: Christian Brauner

mount: Support "nosymfollow" in new mount api

2021-06-01T10:09:27+00:00

Commit dab741e0e02b ("Add a "nosymfollow" mount option.") added support
for the "nosymfollow" mount option allowing to block following symlinks
when resolving paths. The mount option so far was only available in the
old mount api. Make it available in the new mount api as well. Bonus is
that it can be applied to a whole subtree not just a single mount.

Cc: Christoph Hellwig 
Cc: Mattias Nissler 
Cc: Aleksa Sarai 
Cc: Al Viro 
Cc: Ross Zwisler 
Signed-off-by: Christian Brauner