Message-Id: <20200121160512.70887-1-elver@google.com>
Date:   Tue, 21 Jan 2020 17:05:08 +0100
From:   Marco Elver <elver@...gle.com>
To:     elver@...gle.com
Cc:     paulmck@...nel.org, andreyknvl@...gle.com, glider@...gle.com,
        dvyukov@...gle.com, kasan-dev@...glegroups.com,
        linux-kernel@...r.kernel.org, mark.rutland@....com,
        will@...nel.org, peterz@...radead.org, boqun.feng@...il.com,
        arnd@...db.de, viro@...iv.linux.org.uk, dja@...ens.net,
        christophe.leroy@....fr, mpe@...erman.id.au, mhiramat@...nel.org,
        rostedt@...dmis.org, mingo@...nel.org,
        christian.brauner@...ntu.com, daniel@...earbox.net,
        keescook@...omium.org, cyphar@...har.com,
        linux-arch@...r.kernel.org
Subject: [PATCH v2 1/5] include/linux: Add instrumented.h infrastructure

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.]

Suggested-by: Arnd Bergmann <arnd@...db.de>
Signed-off-by: Marco Elver <elver@...gle.com>
Acked-by: Alexander Potapenko <glider@...gle.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

Powered by blists - more mailing lists