The existing tools/testing/selftests/sysctl/ tests include two test
cases, but these use existing production kernel sysctl interfaces.  We
want to expand test coverage but we can't just be looking for random
safe production values to poke at, that's just insane!

Instead just dedicate a test driver for debugging purposes and port the
existing scripts to use it.  This will make it easier for further tests
to be added.

Subsequent patches will extend our test coverage for sysctl.

The stress test driver uses a new license (GPL on Linux, copyleft-next
outside of Linux).  Linus was fine with this [0] and later due to Ted's
and Alans's request ironed out an "or" language clause to use [1] which
is already present upstream.

[0] https://lkml.kernel.org/r/CA+55aFyhxcvD+q7tp+-yrSFDKfR0mOHgyEAe=f_94aKLsOu0Og@mail.gmail.com
[1] https://lkml.kernel.org/r/1495234558.7848.122.camel@linux.intel.com

Link: http://lkml.kernel.org/r/20170630224431.17374-2-mcgrof@kernel.orgSigned-off-by: NLuis R. Rodriguez <mcgrof@kernel.org>
Acked-by: NKees Cook <keescook@chromium.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Sysctl test will fail in some items if the value of /proc/sys/kernel
/sysctrl_writes_strict is 0 as the default value in kernel older than v4.5.

Make this test more robus and compatible with older kernel by checking and
update writes_strict value and restore it when test is done.
Signed-off-by: NOrson Zhai <orson.zhai@linaro.org>
Reviewed-by: NSumit Semwal <sumit.semwal@linaro.org>
Tested-by: NSumit Semwal <sumit.semwal@linaro.org>
Reviewed-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NShuah Khan <shuahkh@osg.samsung.com>

This adds a Make include file which most selftests can then include to
get the run_tests logic.

On its own this has the advantage of some reduction in repetition, and
also means the pass/fail message is defined in fewer places.

However the key advantage is it will allow us to implement install very
simply in a subsequent patch.

The default implementation just executes each program in $(TEST_PROGS).

We use a variable to hold the default implementation of $(RUN_TESTS)
because that gives us a clean way to override it if necessary, ie. using
override. The mount, memory-hotplug and mqueue tests use that to provide
a different implementation.

Tests are not run via /bin/bash, so if they are scripts they must be
executable, we add a+x to several.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NShuah Khan <shuahkh@osg.samsung.com>

This adds several behavioral tests to sysctl string and number writing
to detect unexpected cases that behaved differently when the sysctl
kernel.sysctl_writes_strict != 1.

[ original ]
    root@localhost:~# make test_num
    == Testing sysctl behavior against /proc/sys/kernel/domainname ==
    Writing test file ... ok
    Checking sysctl is not set to test value ... ok
    Writing sysctl from shell ... ok
    Resetting sysctl to original value ... ok
    Writing entire sysctl in single write ... ok
    Writing middle of sysctl after synchronized seek ... FAIL
    Writing beyond end of sysctl ... FAIL
    Writing sysctl with multiple long writes ... FAIL
    Writing entire sysctl in short writes ... FAIL
    Writing middle of sysctl after unsynchronized seek ... ok
    Checking sysctl maxlen is at least 65 ... ok
    Checking sysctl keeps original string on overflow append ... FAIL
    Checking sysctl stays NULL terminated on write ... ok
    Checking sysctl stays NULL terminated on overwrite ... ok
    make: *** [test_num] Error 1
    root@localhost:~# make test_string
    == Testing sysctl behavior against /proc/sys/vm/swappiness ==
    Writing test file ... ok
    Checking sysctl is not set to test value ... ok
    Writing sysctl from shell ... ok
    Resetting sysctl to original value ... ok
    Writing entire sysctl in single write ... ok
    Writing middle of sysctl after synchronized seek ... FAIL
    Writing beyond end of sysctl ... FAIL
    Writing sysctl with multiple long writes ... ok
    make: *** [test_string] Error 1

[ with CONFIG_PROC_SYSCTL_STRICT_WRITES ]
    root@localhost:~# make run_tests
    == Testing sysctl behavior against /proc/sys/kernel/domainname ==
    Writing test file ... ok
    Checking sysctl is not set to test value ... ok
    Writing sysctl from shell ... ok
    Resetting sysctl to original value ... ok
    Writing entire sysctl in single write ... ok
    Writing middle of sysctl after synchronized seek ... ok
    Writing beyond end of sysctl ... ok
    Writing sysctl with multiple long writes ... ok
    Writing entire sysctl in short writes ... ok
    Writing middle of sysctl after unsynchronized seek ... ok
    Checking sysctl maxlen is at least 65 ... ok
    Checking sysctl keeps original string on overflow append ... ok
    Checking sysctl stays NULL terminated on write ... ok
    Checking sysctl stays NULL terminated on overwrite ... ok
    == Testing sysctl behavior against /proc/sys/vm/swappiness ==
    Writing test file ... ok
    Checking sysctl is not set to test value ... ok
    Writing sysctl from shell ... ok
    Resetting sysctl to original value ... ok
    Writing entire sysctl in single write ... ok
    Writing middle of sysctl after synchronized seek ... ok
    Writing beyond end of sysctl ... ok
    Writing sysctl with multiple long writes ... ok
Signed-off-by: NKees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>