linux-toradex.git/kernel/time/posix-stubs.c, branch v6.6-rc1

timers: Prevent union confusion from unexpected restart_syscall()

2023-01-11T18:31:47+00:00

The nanosleep syscalls use the restart_block mechanism, with a quirk:
The `type` and `rmtp`/`compat_rmtp` fields are set up unconditionally on
syscall entry, while the rest of the restart_block is only set up in the
unlikely case that the syscall is actually interrupted by a signal (or
pseudo-signal) that doesn't have a signal handler.

If the restart_block was set up by a previous syscall (futex(...,
FUTEX_WAIT, ...) or poll()) and hasn't been invalidated somehow since then,
this will clobber some of the union fields used by futex_wait_restart() and
do_restart_poll().

If userspace afterwards wrongly calls the restart_syscall syscall,
futex_wait_restart()/do_restart_poll() will read struct fields that have
been clobbered.

This doesn't actually lead to anything particularly interesting because
none of the union fields contain trusted kernel data, and
futex(..., FUTEX_WAIT, ...) and poll() aren't syscalls where it makes much
sense to apply seccomp filters to their arguments.

So the current consequences are just of the "if userspace does bad stuff,
it can damage itself, and that's not a problem" flavor.

But still, it seems like a hazard for future developers, so invalidate the
restart_block when partly setting it up in the nanosleep syscalls.

Signed-off-by: Jann Horn 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20230105134403.754986-1-jannh@google.com

posix-timers: Make do_clock_gettime() static

2022-08-06T08:33:54+00:00

do_clock_gettime() is used only in posix-stubs.c, so make it static. It avoids
a compiler warning too:
time/posix-stubs.c:73:5: warning: no previous prototype for ‘do_clock_gettime’ [-Wmissing-prototypes]

Signed-off-by: Jiri Slaby 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20220719085620.30567-1-jslaby@suse.cz

posix-timers: Make clock_nanosleep() time namespace aware

2020-01-14T11:20:55+00:00

clock_nanosleep() accepts absolute values of expiration time, if the
TIMER_ABSTIME flag is set. This value is in the tasks time namespace,
which has to be converted to the host time namespace.

Co-developed-by: Dmitry Safonov 
Signed-off-by: Andrei Vagin 
Signed-off-by: Dmitry Safonov 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20191112012724.250792-18-dima@arista.com

hrtimers: Prepare hrtimer_nanosleep() for time namespaces

2020-01-14T11:20:55+00:00

clock_nanosleep() accepts absolute values of expiration time when
TIMER_ABSTIME flag is set. This absolute value is inside the task's
time namespace, and has to be converted to the host's time.

There is timens_ktime_to_host() helper for converting time, but
it accepts ktime argument.

As a preparation, make hrtimer_nanosleep() accept a clock value in ktime
instead of timespec64.

Co-developed-by: Dmitry Safonov 
Signed-off-by: Andrei Vagin 
Signed-off-by: Dmitry Safonov 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20191112012724.250792-17-dima@arista.com

posix-clocks: Wire up clock_gettime() with timens offsets

2020-01-14T11:20:52+00:00

Adjust monotonic and boottime clocks with per-timens offsets.  As the
result a process inside time namespace will see timers and clocks corrected
to offsets that were set when the namespace was created

Note that applications usually go through vDSO to get time, which is not
yet adjusted. Further changes will complete time namespace virtualisation
with vDSO support.

Co-developed-by: Dmitry Safonov 
Signed-off-by: Andrei Vagin 
Signed-off-by: Dmitry Safonov 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20191112012724.250792-12-dima@arista.com

time/posix-stubs: Provide compat itimer supoprt for alpha

2020-01-09T17:20:23+00:00

Using compat_sys_getitimer and compat_sys_setitimer on alpha
causes a link failure in the Alpha tinyconfig and other configurations
that turn off CONFIG_POSIX_TIMERS.

Use the same #ifdef check for the stub version as well.

Fixes: 4c22ea2b9120 ("y2038: use compat_{get,set}_itimer on alpha")
Reported-by: Guenter Roeck 
Reported-by: kbuild test robot 
Signed-off-by: Arnd Bergmann 
Signed-off-by: Thomas Gleixner 
Tested-by: Guenter Roeck 
Link: https://lore.kernel.org/r/20191207191043.656328-1-arnd@arndb.de

y2038: syscalls: rename y2038 compat syscalls

2019-02-06T23:13:27+00:00

A lot of system calls that pass a time_t somewhere have an implementation
using a COMPAT_SYSCALL_DEFINEx() on 64-bit architectures, and have
been reworked so that this implementation can now be used on 32-bit
architectures as well.

The missing step is to redefine them using the regular SYSCALL_DEFINEx()
to get them out of the compat namespace and make it possible to build them
on 32-bit architectures.

Any system call that ends in 'time' gets a '32' suffix on its name for
that version, while the others get a '_time32' suffix, to distinguish
them from the normal version, which takes a 64-bit time argument in the
future.

In this step, only 64-bit architectures are changed, doing this rename
first lets us avoid touching the 32-bit architectures twice.

Acked-by: Catalin Marinas 
Signed-off-by: Arnd Bergmann

posix-timers/stubs: Remove license boilerplate

2018-11-23T10:51:21+00:00

The SPDX identifier defines the license of the file already. No need for
the boilerplate.

Signed-off-by: Thomas Gleixner 
Acked-by: Nicolas Pitre 
Acked-by: Kees Cook 
Acked-by: Ingo Molnar 
Acked-by: John Stultz 
Acked-by: Corey Minyard 
Cc: Peter Zijlstra 
Cc: Kate Stewart 
Cc: Philippe Ombredanne 
Cc: Peter Anvin 
Cc: Russell King 
Cc: Richard Cochran 
Cc: "Paul E. McKenney" 
Cc: David Riley 
Cc: Colin Cross 
Cc: Mark Brown 
Cc: Arnd Bergmann 
Link: https://lkml.kernel.org/r/20181031182253.215825217@linutronix.de

time: Add SPDX license identifiers

2018-11-23T10:51:20+00:00

Update the time(r) core files files with the correct SPDX license
identifier based on the license text in the file itself. The SPDX
identifier is a legally binding shorthand, which can be used instead of the
full boiler plate text.

This work is based on a script and data from Philippe Ombredanne, Kate
Stewart and myself. The data has been created with two independent license
scanners and manual inspection.

The following files do not contain any direct license information and have
been omitted from the big initial SPDX changes:

  timeconst.bc: The .bc files were not touched
  time.c, timer.c, timekeeping.c: Licence was deduced from EXPORT_SYMBOL_GPL

As those files do not contain direct license references they fall under the
project license, i.e. GPL V2 only.

Signed-off-by: Thomas Gleixner 
Acked-by: Kees Cook 
Acked-by: Ingo Molnar 
Acked-by: John Stultz 
Acked-by: Corey Minyard 
Cc: Peter Zijlstra 
Cc: Kate Stewart 
Cc: Philippe Ombredanne 
Cc: Russell King 
Cc: Richard Cochran 
Cc: Nicolas Pitre 
Cc: David Riley 
Cc: Colin Cross 
Cc: Mark Brown 
Cc: H. Peter Anvin 
Cc: Paul E. McKenney 
Link: https://lkml.kernel.org/r/20181031182252.879109557@linutronix.de

y2038: globally rename compat_time to old_time32

2018-08-27T12:48:48+00:00

Christoph Hellwig suggested a slightly different path for handling
backwards compatibility with the 32-bit time_t based system calls:

Rather than simply reusing the compat_sys_* entry points on 32-bit
architectures unchanged, we get rid of those entry points and the
compat_time types by renaming them to something that makes more sense
on 32-bit architectures (which don't have a compat mode otherwise),
and then share the entry points under the new name with the 64-bit
architectures that use them for implementing the compatibility.

The following types and interfaces are renamed here, and moved
from linux/compat_time.h to linux/time32.h:

old				new
---				---
compat_time_t			old_time32_t
struct compat_timeval		struct old_timeval32
struct compat_timespec		struct old_timespec32
struct compat_itimerspec	struct old_itimerspec32
ns_to_compat_timeval()		ns_to_old_timeval32()
get_compat_itimerspec64()	get_old_itimerspec32()
put_compat_itimerspec64()	put_old_itimerspec32()
compat_get_timespec64()		get_old_timespec32()
compat_put_timespec64()		put_old_timespec32()

As we already have aliases in place, this patch addresses only the
instances that are relevant to the system call interface in particular,
not those that occur in device drivers and other modules. Those
will get handled separately, while providing the 64-bit version
of the respective interfaces.

I'm not renaming the timex, rusage and itimerval structures, as we are
still debating what the new interface will look like, and whether we
will need a replacement at all.

This also doesn't change the names of the syscall entry points, which can
be done more easily when we actually switch over the 32-bit architectures
to use them, at that point we need to change COMPAT_SYSCALL_DEFINEx to
SYSCALL_DEFINEx with a new name, e.g. with a _time32 suffix.

Suggested-by: Christoph Hellwig 
Link: https://lore.kernel.org/lkml/20180705222110.GA5698@infradead.org/
Signed-off-by: Arnd Bergmann