linux-toradex.git/kernel/sys.c, branch T20_LinuxImageV2.0Beta1_20121218

Avoid using variable-length arrays in kernel/sys.c

2011-10-17T15:24:24+00:00

The size is always valid, but variable-length arrays generate worse code
for no good reason (unless the function happens to be inlined and the
compiler sees the length for the simple constant it is).

Also, there seems to be some code generation problem on POWER, where
Henrik Bakken reports that register r28 can get corrupted under some
subtle circumstances (interrupt happening at the wrong time?).  That all
indicates some seriously broken compiler issues, but since variable
length arrays are bad regardless, there's little point in trying to
chase it down.

"Just don't do that, then".

Reported-by: Henrik Grindal Bakken 
Cc: Benjamin Herrenschmidt 
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds

Add a personality to report 2.6.x version numbers

2011-08-25T17:17:28+00:00

I ran into a couple of programs which broke with the new Linux 3.0
version. Some of those were binary only. I tried to use LD_PRELOAD to
work around it, but it was quite difficult and in one case impossible
because of a mix of 32bit and 64bit executables.

For example, all kind of management software from HP doesnt work, unless
we pretend to run a 2.6 kernel.

$ uname -a
Linux svivoipvnx001 3.0.0-08107-g97cd98f #1062 SMP Fri Aug 12 18:11:45 CEST 2011 i686 i686 i386 GNU/Linux

$ hpacucli ctrl all show

Error: No controllers detected.

$ rpm -qf /usr/sbin/hpacucli
hpacucli-8.75-12.0

Another notable case is that Python now reports "linux3" from
sys.platform(); which in turn can break things that were checking
sys.platform() == "linux2":

https://bugzilla.mozilla.org/show_bug.cgi?id=664564

It seems pretty clear to me though it's a bug in the apps that are using
'==' instead of .startswith(), but this allows us to unbreak broken
programs.

This patch adds a UNAME26 personality that makes the kernel report a
2.6.40+x version number instead. The x is the x in 3.x.

I know this is somewhat ugly, but I didn't find a better workaround, and
compatibility to existing programs is important.

Some programs also read /proc/sys/kernel/osrelease. This can be worked
around in user space with mount --bind (and a mount namespace)

To use:

wget ftp://ftp.kernel.org/pub/linux/kernel/people/ak/uname26/uname26.c
gcc -o uname26 uname26.c
./uname26 program

Signed-off-by: Andi Kleen
Signed-off-by: Linus Torvalds

move RLIMIT_NPROC check from set_user() to do_execve_common()

2011-08-11T18:24:42+00:00

The patch http://lkml.org/lkml/2003/7/13/226 introduced an RLIMIT_NPROC
check in set_user() to check for NPROC exceeding via setuid() and
similar functions.

Before the check there was a possibility to greatly exceed the allowed
number of processes by an unprivileged user if the program relied on
rlimit only.  But the check created new security threat: many poorly
written programs simply don't check setuid() return code and believe it
cannot fail if executed with root privileges.  So, the check is removed
in this patch because of too often privilege escalations related to
buggy programs.

The NPROC can still be enforced in the common code flow of daemons
spawning user processes.  Most of daemons do fork()+setuid()+execve().
The check introduced in execve() (1) enforces the same limit as in
setuid() and (2) doesn't create similar security issues.

Neil Brown suggested to track what specific process has exceeded the
limit by setting PF_NPROC_EXCEEDED process flag.  With the change only
this process would fail on execve(), and other processes' execve()
behaviour is not changed.

Solar Designer suggested to re-check whether NPROC limit is still
exceeded at the moment of execve().  If the process was sleeping for
days between set*uid() and execve(), and the NPROC counter step down
under the limit, the defered execve() failure because NPROC limit was
exceeded days ago would be unexpected.  If the limit is not exceeded
anymore, we clear the flag on successful calls to execve() and fork().

The flag is also cleared on successful calls to set_user() as the limit
was exceeded for the previous user, not the current one.

Similar check was introduced in -ow patches (without the process flag).

v3 - clear PF_NPROC_EXCEEDED on successful calls to set_user().

Reviewed-by: James Morris 
Signed-off-by: Vasiliy Kulikov 
Acked-by: NeilBrown 
Signed-off-by: Linus Torvalds

notifiers: sys: move reboot notifiers into reboot.h

2011-07-26T03:57:14+00:00

It is not necessary to share the same notifier.h.

This patch already moves register_reboot_notifier() and
unregister_reboot_notifier() from kernel/notifier.c to kernel/sys.c.

[amwang@redhat.com: make allyesconfig succeed on ppc64]
Signed-off-by: WANG Cong 
Cc: David Miller 
Cc: "Rafael J. Wysocki" 
Cc: Greg KH 
Signed-off-by: WANG Cong 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6

2011-05-20T01:24:11+00:00

* 'driver-core-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core-2.6: (44 commits)
  debugfs: Silence DEBUG_STRICT_USER_COPY_CHECKS=y warning
  sysfs: remove "last sysfs file:" line from the oops messages
  drivers/base/memory.c: fix warning due to "memory hotplug: Speed up add/remove when blocks are larger than PAGES_PER_SECTION"
  memory hotplug: Speed up add/remove when blocks are larger than PAGES_PER_SECTION
  SYSFS: Fix erroneous comments for sysfs_update_group().
  driver core: remove the driver-model structures from the documentation
  driver core: Add the device driver-model structures to kerneldoc
  Translated Documentation/email-clients.txt
  RAW driver: Remove call to kobject_put().
  reboot: disable usermodehelper to prevent fs access
  efivars: prevent oops on unload when efi is not enabled
  Allow setting of number of raw devices as a module parameter
  Introduce CONFIG_GOOGLE_FIRMWARE
  driver: Google Memory Console
  driver: Google EFI SMI
  x86: Better comments for get_bios_ebda()
  x86: get_bios_ebda_length()
  misc: fix ti-st build issues
  params.c: Use new strtobool function to process boolean inputs
  debugfs: move to new strtobool
  ...

Fix up trivial conflicts in fs/debugfs/file.c due to the same patch
being applied twice, and an unrelated cleanup nearby.

PM: Remove sysdev suspend, resume and shutdown operations

2011-05-11T19:37:15+00:00

Since suspend, resume and shutdown operations in struct sysdev_class
and struct sysdev_driver are not used any more, remove them.  Also
drop sysdev_suspend(), sysdev_resume() and sysdev_shutdown() used
for executing those operations and modify all of their users
accordingly.  This reduces kernel code size quite a bit and reduces
its complexity.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Greg Kroah-Hartman

reboot: disable usermodehelper to prevent fs access

2011-05-07T00:52:32+00:00

In case CONFIG_UEVENT_HELPER_PATH is not set to "", which it
should be on every system, the kernel forks processes during
shutdown, which try to access the rootfs, even when the
binary does not exist. It causes exceptions and long delays in
the disk driver, which gets read requests at the time it tries
to shut down the disk.

This patch disables all kernel-forked processes during reboot to
allow a clean poweroff.

Cc: Tejun Heo 
Tested-By: Anton Guda 
Signed-off-by: Kay Sievers 
Signed-off-by: Greg Kroah-Hartman

userns: user namespaces: convert all capable checks in kernel/sys.c

2011-03-24T02:47:06+00:00

This allows setuid/setgid in containers.  It also fixes some corner cases
where kernel logic foregoes capability checks when uids are equivalent.
The latter will need to be done throughout the whole kernel.

Changelog:
	Jan 11: Use nsown_capable() as suggested by Bastian Blank.
	Jan 11: Fix logic errors in uid checks pointed out by Bastian.
	Feb 15: allow prlimit to current (was regression in previous version)
	Feb 23: remove debugging printks, uninline set_one_prio_perm and
		make it bool, and document its return value.

Signed-off-by: Serge E. Hallyn 
Acked-by: "Eric W. Biederman" 
Acked-by: Daniel Lezcano 
Acked-by: David Howells 
Cc: James Morris 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

userns: allow sethostname in a container

2011-03-24T02:47:03+00:00

Changelog:
	Feb 23: let clone_uts_ns() handle setting uts->user_ns
		To do so we need to pass in the task_struct who'll
		get the utsname, so we can get its user_ns.
	Feb 23: As per Oleg's coment, just pass in tsk, instead of two
		of its members.

Signed-off-by: Serge E. Hallyn 
Acked-by: "Eric W. Biederman" 
Acked-by: Daniel Lezcano 
Acked-by: David Howells 
Cc: James Morris 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

PM / Core: Introduce struct syscore_ops for core subsystems PM

2011-03-14T23:43:46+00:00

Some subsystems need to carry out suspend/resume and shutdown
operations with one CPU on-line and interrupts disabled.  The only
way to register such operations is to define a sysdev class and
a sysdev specifically for this purpose which is cumbersome and
inefficient.  Moreover, the arguments taken by sysdev suspend,
resume and shutdown callbacks are practically never necessary.

For this reason, introduce a simpler interface allowing subsystems
to register operations to be executed very late during system suspend
and shutdown and very early during resume in the form of
strcut syscore_ops objects.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Greg Kroah-Hartman