From: Dmitry Vyukov <dvyukov@google.com>
To: Marco Elver <elver@google.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>,
Andrey Konovalov <andreyknvl@google.com>,
Alexander Potapenko <glider@google.com>,
kasan-dev <kasan-dev@googlegroups.com>,
LKML <linux-kernel@vger.kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Will Deacon <will@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Boqun Feng <boqun.feng@gmail.com>, Arnd Bergmann <arnd@arndb.de>,
Al Viro <viro@zeniv.linux.org.uk>,
Christophe Leroy <christophe.leroy@c-s.fr>,
Daniel Axtens <dja@axtens.net>,
Michael Ellerman <mpe@ellerman.id.au>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Christian Brauner <christian.brauner@ubuntu.com>,
Daniel Borkmann <daniel@iogearbox.net>,
cyphar@cyphar.com, Kees Cook <keescook@chromium.org>,
linux-arch <linux-arch@vger.kernel.org>
Subject: Re: [PATCH 1/5] include/linux: Add instrumented.h infrastructure
Date: Tue, 21 Jan 2020 14:01:13 +0100 [thread overview]
Message-ID: <CACT4Y+bjAn0g980ZCxCn4MkgCsg7KrA69CExCeJZ63eRON5fXw@mail.gmail.com> (raw)
In-Reply-To: <CACT4Y+bnRoKinPopVqyxj4av6_xa_OUN0wwnidpO3dX3iYq_gg@mail.gmail.com>
On Mon, Jan 20, 2020 at 3:45 PM Dmitry Vyukov <dvyukov@google.com> wrote:
>
> On Mon, Jan 20, 2020 at 3:19 PM Marco Elver <elver@google.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 require special instrumentation,
> > providing hooks before and after the access, since we may need to know
> > the actual bytes accessed (currently this is relevant for KCSAN, and is
> > also relevant in future for KMSAN).
> >
> > Suggested-by: Arnd Bergmann <arnd@arndb.de>
> > Signed-off-by: Marco Elver <elver@google.com>
> > ---
> > include/linux/instrumented.h | 153 +++++++++++++++++++++++++++++++++++
> > 1 file changed, 153 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..9f83c8520223
> > --- /dev/null
> > +++ b/include/linux/instrumented.h
> > @@ -0,0 +1,153 @@
> > +/* 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
> > + */
>
> Based on offline discussion, that's what we add for KMSAN:
>
> > +static __always_inline void instrument_read(const volatile void *v, size_t size)
> > +{
> > + kasan_check_read(v, size);
> > + kcsan_check_read(v, size);
>
> KMSAN: nothing
>
> > +}
> > +
> > +/**
> > + * 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);
>
> KMSAN: nothing
>
> > +}
> > +
> > +/**
> > + * 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);
>
> KMSAN: nothing
>
> > +}
> > +
> > +/**
> > + * 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);
>
> KMSAN: nothing
>
> > +}
> > +
> > +/**
> > + * instrument_copy_to_user_pre - 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. At this point the
> > + * actual number of bytes accessed is not yet known.
> > + *
> > + * @dst destination address
> > + * @size maximum access size
> > + */
> > +static __always_inline void
> > +instrument_copy_to_user_pre(const volatile void *src, size_t size)
> > +{
> > + /* Check before, to warn before potential memory corruption. */
> > + kasan_check_read(src, size);
>
> KMSAN: check that (src,size) is initialized
>
> > +}
> > +
> > +/**
> > + * instrument_copy_to_user_post - 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 after the accesses. At this point the
> > + * actual number of bytes accessed should be known.
> > + *
> > + * @dst destination address
> > + * @size maximum access size
> > + * @left number of bytes left that were not copied
> > + */
> > +static __always_inline void
> > +instrument_copy_to_user_post(const volatile void *src, size_t size, size_t left)
> > +{
> > + /* Check after, to avoid false positive if memory was not accessed. */
> > + kcsan_check_read(src, size - left);
>
> KMSAN: nothing
One detail I noticed for KMSAN is that kmsan_copy_to_user has a
special case when @to address is in kernel-space (compat syscalls
doing tricky things), in that case it only copies metadata. We can't
handle this with existing annotations.
* actually copied to ensure there was no information leak. If @to belongs to
* the kernel space (which is possible for compat syscalls), KMSAN just copies
* the metadata.
*/
void kmsan_copy_to_user(const void *to, const void *from, size_t
to_copy, size_t left);
> > +}
> > +
> > +/**
> > + * instrument_copy_from_user_pre - instrument writes of copy_from_user
> > + *
> > + * Instrument writes to kernel memory, that are due to copy_from_user (and
> > + * variants).
> > + *
> > + * The instrumentation must be inserted before the accesses. At this point the
> > + * actual number of bytes accessed is not yet known.
> > + *
> > + * @dst destination address
> > + * @size maximum access size
> > + */
> > +static __always_inline void
> > +instrument_copy_from_user_pre(const volatile void *dst, size_t size)
> > +{
> > + /* Check before, to warn before potential memory corruption. */
> > + kasan_check_write(dst, size);
>
> KMSAN: nothing
>
> > +}
> > +
> > +/**
> > + * instrument_copy_from_user_post - instrument writes of copy_from_user
> > + *
> > + * Instrument writes to kernel memory, that are due to copy_from_user (and
> > + * variants).
> > + *
> > + * The instrumentation must be inserted after the accesses. At this point the
> > + * actual number of bytes accessed should be known.
> > + *
> > + * @dst destination address
> > + * @size maximum access size
> > + * @left number of bytes left that were not copied
> > + */
> > +static __always_inline void
> > +instrument_copy_from_user_post(const volatile void *dst, size_t size, size_t left)
> > +{
> > + /* Check after, to avoid false positive if memory was not accessed. */
> > + kcsan_check_write(dst, size - left);
>
> KMSAN: mark (dst, size-left) as initialized
>
> > +}
> > +
> > +#endif /* _LINUX_INSTRUMENTED_H */
> > --
> > 2.25.0.341.g760bfbb309-goog
> >
next prev parent reply other threads:[~2020-01-21 13:01 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-20 14:19 [PATCH 1/5] include/linux: Add instrumented.h infrastructure Marco Elver
2020-01-20 14:19 ` [PATCH 2/5] asm-generic, atomic-instrumented: Use generic instrumented.h Marco Elver
2020-01-20 14:19 ` [PATCH 3/5] asm-generic, kcsan: Add KCSAN instrumentation for bitops Marco Elver
2020-01-20 14:40 ` Peter Zijlstra
2020-01-20 16:27 ` Paul E. McKenney
2020-01-20 16:52 ` Peter Zijlstra
2020-01-20 20:23 ` Paul E. McKenney
2020-01-21 9:15 ` Peter Zijlstra
2020-01-21 14:21 ` Paul E. McKenney
2020-01-21 14:47 ` Peter Zijlstra
2020-01-21 15:07 ` Marco Elver
2020-01-21 16:16 ` Paul E. McKenney
2020-01-20 14:19 ` [PATCH 4/5] iov_iter: Use generic instrumented.h Marco Elver
2020-01-20 14:19 ` [PATCH 5/5] copy_to_user, copy_from_user: " Marco Elver
2020-01-20 14:51 ` Dmitry Vyukov
2020-01-20 15:05 ` Marco Elver
2020-01-20 14:25 ` [PATCH 1/5] include/linux: Add instrumented.h infrastructure Alexander Potapenko
2020-01-20 14:34 ` Dmitry Vyukov
2020-01-20 15:53 ` Marco Elver
2020-01-20 14:45 ` Dmitry Vyukov
2020-01-20 14:58 ` Dmitry Vyukov
2020-01-20 15:09 ` Dmitry Vyukov
2020-01-20 15:40 ` Marco Elver
2020-01-20 16:06 ` Dmitry Vyukov
2020-01-20 16:25 ` Marco Elver
2020-01-20 16:39 ` Dmitry Vyukov
2020-01-21 9:44 ` Marco Elver
2020-01-21 13:01 ` Dmitry Vyukov [this message]
2020-01-21 16:14 ` Marco Elver
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