On Fri, Apr 29, 2022 at 02:21:26PM +0300, Jani Nikula wrote:
> On Fri, 29 Apr 2022, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> > On Fri, Apr 29, 2022 at 12:39:14PM +0800, David Gow wrote:
> >> KUnit tests are not supposed to run on production systems: they may do
> >> deliberately illegal things to trigger errors, and have security
> >> implications (assertions will often deliberately leak kernel addresses).
> >>
> >> Add a new taint type, TAINT_KUNIT to signal that a KUnit test has been
> >> run. This will be printed as 'N' (for kuNit, as K, U and T were already
> >> taken).
> >>
> >> This should discourage people from running KUnit tests on production
> >> systems, and to make it easier to tell if tests have been run
> >> accidentally (by loading the wrong configuration, etc.)
> >>
> >> Signed-off-by: David Gow <davidgow@xxxxxxxxxx>
> >> ---
> >>
> >> This is something I'd been thinking about for a while, and it came up
> >> again, so I'm finally giving it a go.
> >>
> >> Two notes:
> >> - I decided to add a new type of taint, as none of the existing ones
> >> really seemed to fit. We could live with considering KUnit tests as
> >> TAINT_WARN or TAINT_CRAP or something otherwise, but neither are quite
> >> right.
> >> - The taint_flags table gives a couple of checkpatch.pl errors around
> >> bracket placement. I've kept the new entry consistent with what's
> >> there rather than reformatting the whole table, but be prepared for
> >> complaints about spaces.
> >>
> >> Thoughts?
> >> -- David
> >>
> >> ---
> >> Documentation/admin-guide/tainted-kernels.rst | 1 +
> >> include/linux/panic.h | 3 ++-
> >> kernel/panic.c | 1 +
> >> lib/kunit/test.c | 4 ++++
> >> 4 files changed, 8 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/Documentation/admin-guide/tainted-kernels.rst b/Documentation/admin-guide/tainted-kernels.rst
> >> index ceeed7b0798d..8f18fc4659d4 100644
> >> --- a/Documentation/admin-guide/tainted-kernels.rst
> >> +++ b/Documentation/admin-guide/tainted-kernels.rst
> >> @@ -100,6 +100,7 @@ Bit Log Number Reason that got the kernel tainted
> >> 15 _/K 32768 kernel has been live patched
> >> 16 _/X 65536 auxiliary taint, defined for and used by distros
> >> 17 _/T 131072 kernel was built with the struct randomization plugin
> >> + 18 _/N 262144 a KUnit test has been run
> >> === === ====== ========================================================
> >>
> >> Note: The character ``_`` is representing a blank in this table to make reading
> >> diff --git a/include/linux/panic.h b/include/linux/panic.h
> >> index f5844908a089..1d316c26bf27 100644
> >> --- a/include/linux/panic.h
> >> +++ b/include/linux/panic.h
> >> @@ -74,7 +74,8 @@ static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
> >> #define TAINT_LIVEPATCH 15
> >> #define TAINT_AUX 16
> >> #define TAINT_RANDSTRUCT 17
> >> -#define TAINT_FLAGS_COUNT 18
> >> +#define TAINT_KUNIT 18
> >> +#define TAINT_FLAGS_COUNT 19
> >> #define TAINT_FLAGS_MAX ((1UL << TAINT_FLAGS_COUNT) - 1)
> >>
> >> struct taint_flag {
> >> diff --git a/kernel/panic.c b/kernel/panic.c
> >> index eb4dfb932c85..b24ca63ed738 100644
> >> --- a/kernel/panic.c
> >> +++ b/kernel/panic.c
> >> @@ -404,6 +404,7 @@ const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
> >> [ TAINT_LIVEPATCH ] = { 'K', ' ', true },
> >> [ TAINT_AUX ] = { 'X', ' ', true },
> >> [ TAINT_RANDSTRUCT ] = { 'T', ' ', true },
> >> + [ TAINT_KUNIT ] = { 'N', ' ', false },
> >
> > As kunit tests can be in modules, shouldn't this be "true" here?
> >
> > Overall, I like it, makes sense to me. The "N" will take some getting
> > used to, and I have no idea why "T" was for "struct randomization", that
> > would have allowed you to use "T" instead. Oh well.
>
> Would you consider a patch adding more self-explanatory taint flag
> strings to the output?
Where would those strings go? In the oops report? Or somewhere else?
thanks,
greg k-h
