linux.git/kernel/time/namespace.c, branch v6.12.80

vdso/timens: Refactor copy-pasted find_timens_vvar_page() helper into one copy

2022-12-01T10:35:40+00:00

find_timens_vvar_page() is not architecture-specific, as can be seen from
how all five per-architecture versions of it are the same.

(arm64, powerpc and riscv are exactly the same; x86 and s390 have two
characters difference inside a comment, less blank lines, and mark the
!CONFIG_TIME_NS version as inline.)

Refactor the five copies into a central copy in kernel/time/namespace.c.

Signed-off-by: Jann Horn 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20221130115320.2918447-1-jannh@google.com

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

timens: Delete no-op time_ns_init()

2021-02-05T18:32:09+00:00

Signed-off-by: Alexey Dobriyan 
Signed-off-by: Thomas Gleixner 
Acked-by: Andrei Vagin 
Link: https://lore.kernel.org/r/20201228215402.GA572900@localhost.localdomain

Merge tag 'fixes-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

2020-12-15T00:40:27+00:00

Pull misc fixes from Christian Brauner:
 "This contains several fixes which felt worth being combined into a
  single branch:

   - Use put_nsproxy() instead of open-coding it switch_task_namespaces()

   - Kirill's work to unify lifecycle management for all namespaces. The
     lifetime counters are used identically for all namespaces types.
     Namespaces may of course have additional unrelated counters and
     these are not altered. This work allows us to unify the type of the
     counters and reduces maintenance cost by moving the counter in one
     place and indicating that basic lifetime management is identical
     for all namespaces.

   - Peilin's fix adding three byte padding to Dmitry's
     PTRACE_GET_SYSCALL_INFO uapi struct to prevent an info leak.

   - Two smal patches to convert from the /* fall through */ comment
     annotation to the fallthrough keyword annotation which I had taken
     into my branch and into -next before df561f6688fe ("treewide: Use
     fallthrough pseudo-keyword") made it upstream which fixed this
     tree-wide.

     Since I didn't want to invalidate all testing for other commits I
     didn't rebase and kept them"

* tag 'fixes-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
  nsproxy: use put_nsproxy() in switch_task_namespaces()
  sys: Convert to the new fallthrough notation
  signal: Convert to the new fallthrough notation
  time: Use generic ns_common::count
  cgroup: Use generic ns_common::count
  mnt: Use generic ns_common::count
  user: Use generic ns_common::count
  pid: Use generic ns_common::count
  ipc: Use generic ns_common::count
  uts: Use generic ns_common::count
  net: Use generic ns_common::count
  ns: Add a common refcount into ns_common
  ptrace: Prevent kernel-infoleak in ptrace_get_syscall_info()

namespace: make timens_on_fork() return nothing

2020-11-18T10:06:47+00:00

timens_on_fork() always return 0, and maybe not
need to judge the return value in copy_namespaces().

So make timens_on_fork() return nothing and do not
judge its return val in copy_namespaces().

Signed-off-by: Hui Su 
Link: https://lore.kernel.org/r/20201117161750.GA45121@rlk
Signed-off-by: Christian Brauner

time: Use generic ns_common::count

2020-08-19T12:14:35+00:00

Switch over time namespaces to use the newly introduced common lifetime
counter.

Currently every namespace type has its own lifetime counter which is stored
in the specific namespace struct. The lifetime counters are used
identically for all namespaces types. Namespaces may of course have
additional unrelated counters and these are not altered.

This introduces a common lifetime counter into struct ns_common. The
ns_common struct encompasses information that all namespaces share. That
should include the lifetime counter since its common for all of them.

It also allows us to unify the type of the counters across all namespaces.
Most of them use refcount_t but one uses atomic_t and at least one uses
kref. Especially the last one doesn't make much sense since it's just a
wrapper around refcount_t since 2016 and actually complicates cleanup
operations by having to use container_of() to cast the correct namespace
struct out of struct ns_common.

Having the lifetime counter for the namespaces in one place reduces
maintenance cost. Not just because after switching all namespaces over we
will have removed more code than we added but also because the logic is
more easily understandable and we indicate to the user that the basic
lifetime requirements for all namespaces are currently identical.

Signed-off-by: Kirill Tkhai 
Reviewed-by: Kees Cook 
Acked-by: Christian Brauner 
Link: https://lore.kernel.org/r/159644982033.604812.9406853013011123238.stgit@localhost.localdomain
Signed-off-by: Christian Brauner

nsproxy: support CLONE_NEWTIME with setns()

2020-07-08T09:14:22+00:00

So far setns() was missing time namespace support. This was partially due
to it simply not being implemented but also because vdso_join_timens()
could still fail which made switching to multiple namespaces atomically
problematic. This is now fixed so support CLONE_NEWTIME with setns()

Signed-off-by: Christian Brauner 
Reviewed-by: Andrei Vagin 
Cc: Thomas Gleixner 
Cc: Michael Kerrisk 
Cc: Serge Hallyn 
Cc: Dmitry Safonov 
Link: https://lore.kernel.org/r/20200706154912.3248030-4-christian.brauner@ubuntu.com

timens: add timens_commit() helper

2020-07-08T09:14:21+00:00

Wrap the calls to timens_set_vvar_page() and vdso_join_timens() in
timens_on_fork() and timens_install() in a new timens_commit() helper.
We'll use this helper in a follow-up patch in nsproxy too.

Signed-off-by: Christian Brauner 
Reviewed-by: Andrei Vagin 
Cc: Will Deacon 
Cc: Vincenzo Frascino 
Cc: Thomas Gleixner 
Cc: Catalin Marinas 
Cc: Mark Rutland 
Cc: Dmitry Safonov 
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20200706154912.3248030-3-christian.brauner@ubuntu.com

timens: make vdso_join_timens() always succeed

2020-07-08T09:14:21+00:00

As discussed on-list (cf. [1]), in order to make setns() support time
namespaces when attaching to multiple namespaces at once properly we
need to tweak vdso_join_timens() to always succeed. So switch
vdso_join_timens() to using a read lock and replacing
mmap_write_lock_killable() to mmap_read_lock() as we discussed.

Last cycle setns() was changed to support attaching to multiple namespaces
atomically. This requires all namespaces to have a point of no return where
they can't fail anymore. Specifically, _install() is
allowed to perform permission checks and install the namespace into the new
struct nsset that it has been given but it is not allowed to make visible
changes to the affected task. Once _install() returns
anything that the given namespace type requires to be setup in addition
needs to ideally be done in a function that can't fail or if it fails the
failure is not fatal. For time namespaces the relevant functions that fall
into this category are timens_set_vvar_page() and vdso_join_timens().
Currently the latter can fail but doesn't need to. With this we can go on
to implement a timens_commit() helper in a follow up patch to be used by
setns().

[1]: https://lore.kernel.org/lkml/20200611110221.pgd3r5qkjrjmfqa2@wittgenstein

Signed-off-by: Christian Brauner 
Reviewed-by: Andrei Vagin 
Cc: Will Deacon 
Cc: Vincenzo Frascino 
Cc: Thomas Gleixner 
Cc: Andy Lutomirski 
Cc: Catalin Marinas 
Cc: Mark Rutland 
Cc: Dmitry Safonov 
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20200706154912.3248030-2-christian.brauner@ubuntu.com

nsproxy: add struct nsset

2020-05-09T11:57:12+00:00

Add a simple struct nsset. It holds all necessary pieces to switch to a new
set of namespaces without leaving a task in a half-switched state which we
will make use of in the next patch. This patch switches the existing setns
logic over without causing a change in setns() behavior. This brings
setns() closer to how unshare() works(). The prepare_ns() function is
responsible to prepare all necessary information. This has two reasons.
First it minimizes dependencies between individual namespaces, i.e. all
install handler can expect that all fields are properly initialized
independent in what order they are called in. Second, this makes the code
easier to maintain and easier to follow if it needs to be changed.

The prepare_ns() helper will only be switched over to use a flags argument
in the next patch. Here it will still use nstype as a simple integer
argument which was argued would be clearer. I'm not particularly
opinionated about this if it really helps or not. The struct nsset itself
already contains the flags field since its name already indicates that it
can contain information required by different namespaces. None of this
should have functional consequences.

Signed-off-by: Christian Brauner 
Reviewed-by: Serge Hallyn 
Cc: Eric W. Biederman 
Cc: Serge Hallyn 
Cc: Jann Horn 
Cc: Michael Kerrisk 
Cc: Aleksa Sarai 
Link: https://lore.kernel.org/r/20200505140432.181565-2-christian.brauner@ubuntu.com