Pull random updates from Ted Ts'o:
"Add wait_for_random_bytes() and get_random_*_wait() functions so that
callers can more safely get random bytes if they can block until the
CRNG is initialized.
Also print a warning if get_random_*() is called before the CRNG is
initialized. By default, only one single-line warning will be printed
per boot. If CONFIG_WARN_ALL_UNSEEDED_RANDOM is defined, then a
warning will be printed for each function which tries to get random
bytes before the CRNG is initialized. This can get spammy for certain
architecture types, so it is not enabled by default"
* tag 'random_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/random:
random: reorder READ_ONCE() in get_random_uXX
random: suppress spammy warnings about unseeded randomness
random: warn when kernel uses unseeded randomness
net/route: use get_random_int for random counter
net/neighbor: use get_random_u32 for 32-bit hash random
rhashtable: use get_random_u32 for hash_rnd
ceph: ensure RNG is seeded before using
iscsi: ensure RNG is seeded before use
cifs: use get_random_u32 for 32-bit lock random
random: add get_random_{bytes,u32,u64,int,long,once}_wait family
random: add wait_for_random_bytes() API
Unfortunately, on some models of some architectures getting a fully
seeded CRNG is extremely difficult, and so this can result in dmesg
getting spammed for a surprisingly long time. This is really bad from
a security perspective, and so architecture maintainers really need to
do what they can to get the CRNG seeded sooner after the system is
booted. However, users can't do anything actionble to address this,
and spamming the kernel messages log will only just annoy people.
For developers who want to work on improving this situation,
CONFIG_WARN_UNSEEDED_RANDOM has been renamed to
CONFIG_WARN_ALL_UNSEEDED_RANDOM. By default the kernel will always
print the first use of unseeded randomness. This way, hopefully the
security obsessed will be happy that there is _some_ indication when
the kernel boots there may be a potential issue with that architecture
or subarchitecture. To see all uses of unseeded randomness,
developers can enable CONFIG_WARN_ALL_UNSEEDED_RANDOM.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This adds a new stress test driver for kmod: the kernel module loader.
The new stress test driver, test_kmod, is only enabled as a module right
now. It should be possible to load this as built-in and load tests
early (refer to the force_init_test module parameter), however since a
lot of test can get a system out of memory fast we leave this disabled
for now.
Using a system with 1024 MiB of RAM can *easily* get your kernel OOM
fast with this test driver.
The test_kmod driver exposes API knobs for us to fine tune simple
request_module() and get_fs_type() calls. Since these API calls only
allow each one parameter a test driver for these is rather simple.
Other factors that can help out test driver though are the number of
calls we issue and knowing current limitations of each. This exposes
configuration as much as possible through userspace to be able to build
tests directly from userspace.
Since it allows multiple misc devices its will eventually (once we add a
knob to let us create new devices at will) also be possible to perform
more tests in parallel, provided you have enough memory.
We only enable tests we know work as of right now.
Demo screenshots:
# tools/testing/selftests/kmod/kmod.sh
kmod_test_0001_driver: OK! - loading kmod test
kmod_test_0001_driver: OK! - Return value: 256 (MODULE_NOT_FOUND), expected MODULE_NOT_FOUND
kmod_test_0001_fs: OK! - loading kmod test
kmod_test_0001_fs: OK! - Return value: -22 (-EINVAL), expected -EINVAL
kmod_test_0002_driver: OK! - loading kmod test
kmod_test_0002_driver: OK! - Return value: 256 (MODULE_NOT_FOUND), expected MODULE_NOT_FOUND
kmod_test_0002_fs: OK! - loading kmod test
kmod_test_0002_fs: OK! - Return value: -22 (-EINVAL), expected -EINVAL
kmod_test_0003: OK! - loading kmod test
kmod_test_0003: OK! - Return value: 0 (SUCCESS), expected SUCCESS
kmod_test_0004: OK! - loading kmod test
kmod_test_0004: OK! - Return value: 0 (SUCCESS), expected SUCCESS
kmod_test_0005: OK! - loading kmod test
kmod_test_0005: OK! - Return value: 0 (SUCCESS), expected SUCCESS
kmod_test_0006: OK! - loading kmod test
kmod_test_0006: OK! - Return value: 0 (SUCCESS), expected SUCCESS
kmod_test_0005: OK! - loading kmod test
kmod_test_0005: OK! - Return value: 0 (SUCCESS), expected SUCCESS
kmod_test_0006: OK! - loading kmod test
kmod_test_0006: OK! - Return value: 0 (SUCCESS), expected SUCCESS
XXX: add test restult for 0007
Test completed
You can also request for specific tests:
# tools/testing/selftests/kmod/kmod.sh -t 0001
kmod_test_0001_driver: OK! - loading kmod test
kmod_test_0001_driver: OK! - Return value: 256 (MODULE_NOT_FOUND), expected MODULE_NOT_FOUND
kmod_test_0001_fs: OK! - loading kmod test
kmod_test_0001_fs: OK! - Return value: -22 (-EINVAL), expected -EINVAL
Test completed
Lastly, the current available number of tests:
# tools/testing/selftests/kmod/kmod.sh --help
Usage: tools/testing/selftests/kmod/kmod.sh [ -t <4-number-digit> ]
Valid tests: 0001-0009
0001 - Simple test - 1 thread for empty string
0002 - Simple test - 1 thread for modules/filesystems that do not exist
0003 - Simple test - 1 thread for get_fs_type() only
0004 - Simple test - 2 threads for get_fs_type() only
0005 - multithreaded tests with default setup - request_module() only
0006 - multithreaded tests with default setup - get_fs_type() only
0007 - multithreaded tests with default setup test request_module() and get_fs_type()
0008 - multithreaded - push kmod_concurrent over max_modprobes for request_module()
0009 - multithreaded - push kmod_concurrent over max_modprobes for get_fs_type()
The following test cases currently fail, as such they are not currently
enabled by default:
# tools/testing/selftests/kmod/kmod.sh -t 0008
# tools/testing/selftests/kmod/kmod.sh -t 0009
To be sure to run them as intended please unload both of the modules:
o test_module
o xfs
And ensure they are not loaded on your system prior to testing them. If
you use these paritions for your rootfs you can change the default test
driver used for get_fs_type() by exporting it into your environment. For
example of other test defaults you can override refer to kmod.sh
allow_user_defaults().
Behind the scenes this is how we fine tune at a test case prior to
hitting a trigger to run it:
cat /sys/devices/virtual/misc/test_kmod0/config
echo -n "2" > /sys/devices/virtual/misc/test_kmod0/config_test_case
echo -n "ext4" > /sys/devices/virtual/misc/test_kmod0/config_test_fs
echo -n "80" > /sys/devices/virtual/misc/test_kmod0/config_num_threads
cat /sys/devices/virtual/misc/test_kmod0/config
echo -n "1" > /sys/devices/virtual/misc/test_kmod0/config_num_threads
Finally to trigger:
echo -n "1" > /sys/devices/virtual/misc/test_kmod0/trigger_config
The kmod.sh script uses the above constructs to build different test cases.
A bit of interpretation of the current failures follows, first two
premises:
a) When request_module() is used userspace figures out an optimized
version of module order for us. Once it finds the modules it needs, as
per depmod symbol dep map, it will finit_module() the respective
modules which are needed for the original request_module() request.
b) We have an optimization in place whereby if a kernel uses
request_module() on a module already loaded we never bother userspace
as the module already is loaded. This is all handled by kernel/kmod.c.
A few things to consider to help identify root causes of issues:
0) kmod 19 has a broken heuristic for modules being assumed to be
built-in to your kernel and will return 0 even though request_module()
failed. Upgrade to a newer version of kmod.
1) A get_fs_type() call for "xfs" will request_module() for "fs-xfs",
not for "xfs". The optimization in kernel described in b) fails to
catch if we have a lot of consecutive get_fs_type() calls. The reason
is the optimization in place does not look for aliases. This means two
consecutive get_fs_type() calls will bump kmod_concurrent, whereas
request_module() will not.
This one explanation why test case 0009 fails at least once for
get_fs_type().
2) If a module fails to load --- for whatever reason (kmod_concurrent
limit reached, file not yet present due to rootfs switch, out of
memory) we have a period of time during which module request for the
same name either with request_module() or get_fs_type() will *also*
fail to load even if the file for the module is ready.
This explains why *multiple* NULLs are possible on test 0009.
3) finit_module() consumes quite a bit of memory.
4) Filesystems typically also have more dependent modules than other
modules, its important to note though that even though a get_fs_type()
call does not incur additional kmod_concurrent bumps, since userspace
loads dependencies it finds it needs via finit_module_fd(), it *will*
take much more memory to load a module with a lot of dependencies.
Because of 3) and 4) we will easily run into out of memory failures with
certain tests. For instance test 0006 fails on qemu with 1024 MiB of RAM.
It panics a box after reaping all userspace processes and still not
having enough memory to reap.
[arnd@arndb.de: add dependencies for test module]
Link: http://lkml.kernel.org/r/20170630154834.3689272-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/20170628223155.26472-3-mcgrof@kernel.org
Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Jessica Yu <jeyu@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Michal Marek <mmarek@suse.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Split SOFTLOCKUP_DETECTOR from LOCKUP_DETECTOR, and split
HARDLOCKUP_DETECTOR_PERF from HARDLOCKUP_DETECTOR.
LOCKUP_DETECTOR implies the general boot, sysctl, and programming
interfaces for the lockup detectors.
An architecture that wants to use a hard lockup detector must define
HAVE_HARDLOCKUP_DETECTOR_PERF or HAVE_HARDLOCKUP_DETECTOR_ARCH.
Alternatively an arch can define HAVE_NMI_WATCHDOG, which provides the
minimum arch_touch_nmi_watchdog, and it otherwise does its own thing and
does not implement the LOCKUP_DETECTOR interfaces.
sparc is unusual in that it has started to implement some of the
interfaces, but not fully yet. It should probably be converted to a full
HAVE_HARDLOCKUP_DETECTOR_ARCH.
[npiggin@gmail.com: fix]
Link: http://lkml.kernel.org/r/20170617223522.66c0ad88@roar.ozlabs.ibm.com
Link: http://lkml.kernel.org/r/20170616065715.18390-4-npiggin@gmail.com
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Don Zickus <dzickus@redhat.com>
Reviewed-by: Babu Moger <babu.moger@oracle.com>
Tested-by: Babu Moger <babu.moger@oracle.com> [sparc]
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull documentation updates from Jonathan Corbet:
"There has been a fair amount of activity in the docs tree this time
around. Highlights include:
- Conversion of a bunch of security documentation into RST
- The conversion of the remaining DocBook templates by The Amazing
Mauro Machine. We can now drop the entire DocBook build chain.
- The usual collection of fixes and minor updates"
* tag 'docs-4.13' of git://git.lwn.net/linux: (90 commits)
scripts/kernel-doc: handle DECLARE_HASHTABLE
Documentation: atomic_ops.txt is core-api/atomic_ops.rst
Docs: clean up some DocBook loose ends
Make the main documentation title less Geocities
Docs: Use kernel-figure in vidioc-g-selection.rst
Docs: fix table problems in ras.rst
Docs: Fix breakage with Sphinx 1.5 and upper
Docs: Include the Latex "ifthen" package
doc/kokr/howto: Only send regression fixes after -rc1
docs-rst: fix broken links to dynamic-debug-howto in kernel-parameters
doc: Document suitability of IBM Verse for kernel development
Doc: fix a markup error in coding-style.rst
docs: driver-api: i2c: remove some outdated information
Documentation: DMA API: fix a typo in a function name
Docs: Insert missing space to separate link from text
doc/ko_KR/memory-barriers: Update control-dependencies example
Documentation, kbuild: fix typo "minimun" -> "minimum"
docs: Fix some formatting issues in request-key.rst
doc: ReSTify keys-trusted-encrypted.txt
doc: ReSTify keys-request-key.txt
...
Pull locking updates from Ingo Molnar:
"The main changes in this cycle were:
- Add CONFIG_REFCOUNT_FULL=y to allow the disabling of the 'full'
(robustness checked) refcount_t implementation with slightly lower
runtime overhead. (Kees Cook)
The lighter weight variant is the default. The two variants use the
same API. Having this variant was a precondition by some
maintainers to merge refcount_t cleanups.
- Add lockdep support for rtmutexes (Peter Zijlstra)
- liblockdep fixes and improvements (Sasha Levin, Ben Hutchings)
- ... misc fixes and improvements"
* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits)
locking/refcount: Remove the half-implemented refcount_sub() API
locking/refcount: Create unchecked atomic_t implementation
locking/rtmutex: Don't initialize lockdep when not required
locking/selftest: Add RT-mutex support
locking/selftest: Remove the bad unlock ordering test
rt_mutex: Add lockdep annotations
MAINTAINERS: Claim atomic*_t maintainership
locking/x86: Remove the unused atomic_inc_short() methd
tools/lib/lockdep: Remove private kernel headers
tools/lib/lockdep: Hide liblockdep output from test results
tools/lib/lockdep: Add dummy current_gfp_context()
tools/include: Add IS_ERR_OR_NULL to err.h
tools/lib/lockdep: Add empty __is_[module,kernel]_percpu_address
tools/lib/lockdep: Include err.h
tools/include: Add (mostly) empty include/linux/sched/mm.h
tools/lib/lockdep: Use LDFLAGS
tools/lib/lockdep: Remove double-quotes from soname
tools/lib/lockdep: Fix object file paths used in an out-of-tree build
tools/lib/lockdep: Fix compilation for 4.11
tools/lib/lockdep: Don't mix fd-based and stream IO
...
This enables an important dmesg notification about when drivers have
used the crng without it being seeded first. Prior, these errors would
occur silently, and so there hasn't been a great way of diagnosing these
types of bugs for obscure setups. By adding this as a config option, we
can leave it on by default, so that we learn where these issues happen,
in the field, will still allowing some people to turn it off, if they
really know what they're doing and do not want the log entries.
However, we don't leave it _completely_ by default. An earlier version
of this patch simply had `default y`. I'd really love that, but it turns
out, this problem with unseeded randomness being used is really quite
present and is going to take a long time to fix. Thus, as a compromise
between log-messages-for-all and nobody-knows, this is `default y`,
except it is also `depends on DEBUG_KERNEL`. This will ensure that the
curious see the messages while others don't have to.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
RCU's debugging Kconfig options are in the unintuitive location
lib/Kconfig.debug, and there are enough of them that it would be good for
them to be more centralized. This commit therefore extracts RCU's Kconfig
options from init/Kconfig into a new kernel/rcu/Kconfig.debug file.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
RCU's debugfs tracing used to be the only reasonable low-level debug
information available, but ftrace and event tracing has since surpassed
the RCU debugfs level of usefulness. This commit therefore removes
RCU's debugfs tracing.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The sparse-based checking for non-RCU accesses to RCU-protected pointers
has been around for a very long time, and it is now the only type of
sparse-based checking that is optional. This commit therefore makes
it unconditional.
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
The PROVE_RCU_REPEATEDLY Kconfig option was initially added due to
the volume of messages from PROVE_RCU: Doing just one per boot would
have required excessive numbers of boots to locate them all. However,
PROVE_RCU messages are now relatively rare, so there is no longer any
reason to need more than one such message per boot. This commit therefore
removes the PROVE_RCU_REPEATEDLY Kconfig option.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
The RCU_TORTURE_TEST_SLOW_PREINIT, RCU_TORTURE_TEST_SLOW_PREINIT_DELAY,
RCU_TORTURE_TEST_SLOW_PREINIT_DELAY, RCU_TORTURE_TEST_SLOW_INIT,
RCU_TORTURE_TEST_SLOW_INIT_DELAY, RCU_TORTURE_TEST_SLOW_CLEANUP,
and RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY Kconfig options are only
useful for torture testing, and there are the rcutree.gp_cleanup_delay,
rcutree.gp_init_delay, and rcutree.gp_preinit_delay kernel boot parameters
that rcutorture can use instead. The effect of these parameters is to
artificially slow down grace period initialization and cleanup in order
to make some types of race conditions happen more often.
This commit therefore simplifies Tree RCU a bit by removing the Kconfig
options and adding the corresponding kernel parameters to rcutorture's
.boot files instead. However, this commit also leaves out the kernel
parameters for TREE02, TREE04, and TREE07 in order to have about the
same number of tests slowed as not slowed. TREE01, TREE03, TREE05,
and TREE06 are slowed, and the rest are not slowed.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
The filesystem documentation was moved from DocBook to
Documentation/filesystems/. Update it at the sources.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Pull documentation update from Jonathan Corbet:
"A reasonably busy cycle for documentation this time around. There is a
new guide for user-space API documents, rather sparsely populated at
the moment, but it's a start. Markus improved the infrastructure for
converting diagrams. Mauro has converted much of the USB documentation
over to RST. Plus the usual set of fixes, improvements, and tweaks.
There's a bit more than the usual amount of reaching out of
Documentation/ to fix comments elsewhere in the tree; I have acks for
those where I could get them"
* tag 'docs-4.12' of git://git.lwn.net/linux: (74 commits)
docs: Fix a couple typos
docs: Fix a spelling error in vfio-mediated-device.txt
docs: Fix a spelling error in ioctl-number.txt
MAINTAINERS: update file entry for HSI subsystem
Documentation: allow installing man pages to a user defined directory
Doc/PM: Sync with intel_powerclamp code behavior
zr364xx.rst: usb/devices is now at /sys/kernel/debug/
usb.rst: move documentation from proc_usb_info.txt to USB ReST book
convert philips.txt to ReST and add to media docs
docs-rst: usb: update old usbfs-related documentation
arm: Documentation: update a path name
docs: process/4.Coding.rst: Fix a couple of document refs
docs-rst: fix usb cross-references
usb: gadget.h: be consistent at kernel doc macros
usb: composite.h: fix two warnings when building docs
usb: get rid of some ReST doc build errors
usb.rst: get rid of some Sphinx errors
usb/URB.txt: convert to ReST and update it
usb/persist.txt: convert to ReST and add to driver-api book
usb/hotplug.txt: convert to ReST and add to driver-api book
...
AVR32 architecture has been removed from the Linux kernel sources, hence
clean up the architecture related symbols in lib/Kconfig.debug.
Signed-off-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
CONFIG_PROVE_LOCKING_SMALL shrinks the memory usage of lockdep so the
kernel text, data, and bss fit in the required 32MB limit, but this
option is not set for every config that enables lockdep.
A 4.10 kernel fails to boot with the console output
Kernel: Using 8 locked TLB entries for main kernel image.
hypervisor_tlb_lock[2000000:0:8000000071c007c3:1]: errors with f
Program terminated
with these config options
CONFIG_LOCKDEP=y
CONFIG_LOCK_STAT=y
CONFIG_PROVE_LOCKING=n
To fix, rename CONFIG_PROVE_LOCKING_SMALL to CONFIG_LOCKDEP_SMALL, and
enable this option with CONFIG_LOCKDEP=y so we get the reduced memory
usage every time lockdep is turned on.
Tested that CONFIG_LOCKDEP_SMALL is set to 'y' if and only if
CONFIG_LOCKDEP is set to 'y'. When other lockdep-related config options
that select CONFIG_LOCKDEP are enabled (e.g. CONFIG_LOCK_STAT or
CONFIG_PROVE_LOCKING), verified that CONFIG_LOCKDEP_SMALL is also
enabled.
Fixes: e6b5f1be7a ("config: Adding the new config parameter CONFIG_PROVE_LOCKING_SMALL for sparc")
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Babu Moger <babu.moger@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
A bunch of documentation files have moved, correct the paths.
Signed-off-by: Hans Holmberg <hans@pixelmunchies.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Pull locking fixes from Ingo Molnar:
"The main change is the uninlining of large refcount_t APIs, plus a
header dependency fix.
Note that the uninlining allowed us to enable the underflow/overflow
warnings unconditionally and remove the debug Kconfig switch: this
might trigger new warnings in buggy code and turn
crashes/use-after-free bugs into less harmful memory leaks"
* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/refcounts: Add missing kernel.h header to have UINT_MAX defined
locking/refcounts: Out-of-line everything
