Re: [PATCH v2 1/5] include/linux: Add instrumented.h infrastructure

["Paul E. McKenney" <paulmck@kernel.org>]

On Fri, Jan 24, 2020 at 12:22:56PM +0100, Dmitry Vyukov wrote:
> On Tue, Jan 21, 2020 at 5:05 PM 'Marco Elver' via kasan-dev
> <kasan-dev@googlegroups.com> wrote:
> >
> > This adds instrumented.h, which provides generic wrappers for memory
> > access instrumentation that the compiler cannot emit for various
> > sanitizers. Currently this unifies KASAN and KCSAN instrumentation. In
> > future this will also include KMSAN instrumentation.
> >
> > Note that, copy_{to,from}_user should use special instrumentation, since
> > we should be able to instrument both source and destination memory
> > accesses if both are kernel memory.
> >
> > The current patch only instruments the memory access where the address
> > is always in kernel space, however, both may in fact be kernel addresses
> > when a compat syscall passes an argument allocated in the kernel to a
> > real syscall. In a future change, both KASAN and KCSAN should check both
> > addresses in such cases, as well as KMSAN will make use of both
> > addresses. [It made more sense to provide the completed function
> > signature, rather than updating it and changing all locations again at a
> > later time.]
> 
> Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

I have applied this and the other four with Dmitry's Reviewed-by.

Thank you all!

							Thanx, Paul

> > Suggested-by: Arnd Bergmann <arnd@arndb.de>
> > Signed-off-by: Marco Elver <elver@google.com>
> > Acked-by: Alexander Potapenko <glider@google.com>
> > ---
> > v2:
> > * Simplify header, since we currently do not need pre/post user-copy
> >   distinction.
> > * Make instrument_copy_{to,from}_user function arguments match
> >   copy_{to,from}_user and update rationale in commit message.
> > ---
> >  include/linux/instrumented.h | 109 +++++++++++++++++++++++++++++++++++
> >  1 file changed, 109 insertions(+)
> >  create mode 100644 include/linux/instrumented.h
> >
> > diff --git a/include/linux/instrumented.h b/include/linux/instrumented.h
> > new file mode 100644
> > index 000000000000..43e6ea591975
> > --- /dev/null
> > +++ b/include/linux/instrumented.h
> > @@ -0,0 +1,109 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +
> > +/*
> > + * This header provides generic wrappers for memory access instrumentation that
> > + * the compiler cannot emit for: KASAN, KCSAN.
> > + */
> > +#ifndef _LINUX_INSTRUMENTED_H
> > +#define _LINUX_INSTRUMENTED_H
> > +
> > +#include <linux/compiler.h>
> > +#include <linux/kasan-checks.h>
> > +#include <linux/kcsan-checks.h>
> > +#include <linux/types.h>
> > +
> > +/**
> > + * instrument_read - instrument regular read access
> > + *
> > + * Instrument a regular read access. The instrumentation should be inserted
> > + * before the actual read happens.
> > + *
> > + * @ptr address of access
> > + * @size size of access
> > + */
> > +static __always_inline void instrument_read(const volatile void *v, size_t size)
> > +{
> > +       kasan_check_read(v, size);
> > +       kcsan_check_read(v, size);
> > +}
> > +
> > +/**
> > + * instrument_write - instrument regular write access
> > + *
> > + * Instrument a regular write access. The instrumentation should be inserted
> > + * before the actual write happens.
> > + *
> > + * @ptr address of access
> > + * @size size of access
> > + */
> > +static __always_inline void instrument_write(const volatile void *v, size_t size)
> > +{
> > +       kasan_check_write(v, size);
> > +       kcsan_check_write(v, size);
> > +}
> > +
> > +/**
> > + * instrument_atomic_read - instrument atomic read access
> > + *
> > + * Instrument an atomic read access. The instrumentation should be inserted
> > + * before the actual read happens.
> > + *
> > + * @ptr address of access
> > + * @size size of access
> > + */
> > +static __always_inline void instrument_atomic_read(const volatile void *v, size_t size)
> > +{
> > +       kasan_check_read(v, size);
> > +       kcsan_check_atomic_read(v, size);
> > +}
> > +
> > +/**
> > + * instrument_atomic_write - instrument atomic write access
> > + *
> > + * Instrument an atomic write access. The instrumentation should be inserted
> > + * before the actual write happens.
> > + *
> > + * @ptr address of access
> > + * @size size of access
> > + */
> > +static __always_inline void instrument_atomic_write(const volatile void *v, size_t size)
> > +{
> > +       kasan_check_write(v, size);
> > +       kcsan_check_atomic_write(v, size);
> > +}
> > +
> > +/**
> > + * instrument_copy_to_user - instrument reads of copy_to_user
> > + *
> > + * Instrument reads from kernel memory, that are due to copy_to_user (and
> > + * variants). The instrumentation must be inserted before the accesses.
> > + *
> > + * @to destination address
> > + * @from source address
> > + * @n number of bytes to copy
> > + */
> > +static __always_inline void
> > +instrument_copy_to_user(void __user *to, const void *from, unsigned long n)
> > +{
> > +       kasan_check_read(from, n);
> > +       kcsan_check_read(from, n);
> > +}
> > +
> > +/**
> > + * instrument_copy_from_user - instrument writes of copy_from_user
> > + *
> > + * Instrument writes to kernel memory, that are due to copy_from_user (and
> > + * variants). The instrumentation should be inserted before the accesses.
> > + *
> > + * @to destination address
> > + * @from source address
> > + * @n number of bytes to copy
> > + */
> > +static __always_inline void
> > +instrument_copy_from_user(const void *to, const void __user *from, unsigned long n)
> > +{
> > +       kasan_check_write(to, n);
> > +       kcsan_check_write(to, n);
> > +}
> > +
> > +#endif /* _LINUX_INSTRUMENTED_H */
> > --
> > 2.25.0.341.g760bfbb309-goog
> >
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