Date:   Tue, 14 Dec 2021 17:20:12 +0100
In-Reply-To: <20211214162050.660953-1-glider@google.com>
Message-Id: <20211214162050.660953-6-glider@google.com>
Mime-Version: 1.0
References: <20211214162050.660953-1-glider@google.com>
Subject: [PATCH 05/43] asm: x86: instrument usercopy in get_user() and __put_user_size()
From:   Alexander Potapenko <glider@google.com>
To:     glider@google.com
Cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andrey Konovalov <andreyknvl@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Arnd Bergmann <arnd@arndb.de>, Borislav Petkov <bp@alien8.de>,
        Christoph Hellwig <hch@lst.de>,
        Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Eric Dumazet <edumazet@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Ilya Leoshkevich <iii@linux.ibm.com>,
        Ingo Molnar <mingo@redhat.com>, Jens Axboe <axboe@kernel.dk>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Kees Cook <keescook@chromium.org>,
        Marco Elver <elver@google.com>,
        Matthew Wilcox <willy@infradead.org>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Pekka Enberg <penberg@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Petr Mladek <pmladek@suse.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Vegard Nossum <vegard.nossum@oracle.com>,
        Vlastimil Babka <vbabka@suse.cz>, linux-mm@kvack.org,
        linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Use hooks from instrumented.h to notify bug detection tools about
usercopy events in get_user() and put_user_size().

It's still unclear how to instrument put_user(), which assumes that
instrumentation code doesn't clobber RAX.

Signed-off-by: Alexander Potapenko <glider@google.com>
---
Link: https://linux-review.googlesource.com/id/Ia9f12bfe5832623250e20f1859fdf5cc485a2fce
---
 arch/x86/include/asm/uaccess.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 33a68407def3f..86ad5ab211e97 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -5,6 +5,7 @@
  * User space memory access functions
  */
 #include <linux/compiler.h>
+#include <linux/instrumented.h>
 #include <linux/kasan-checks.h>
 #include <linux/string.h>
 #include <asm/asm.h>
@@ -126,11 +127,13 @@ extern int __get_user_bad(void);
 	int __ret_gu;							\
 	register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);		\
 	__chk_user_ptr(ptr);						\
+	instrument_copy_from_user_before((void *)&(x), ptr, sizeof(*(ptr))); \
 	asm volatile("call __" #fn "_%P4"				\
 		     : "=a" (__ret_gu), "=r" (__val_gu),		\
 			ASM_CALL_CONSTRAINT				\
 		     : "0" (ptr), "i" (sizeof(*(ptr))));		\
 	(x) = (__force __typeof__(*(ptr))) __val_gu;			\
+	instrument_copy_from_user_after((void *)&(x), ptr, sizeof(*(ptr)), 0); \
 	__builtin_expect(__ret_gu, 0);					\
 })
 
@@ -275,7 +278,9 @@ extern void __put_user_nocheck_8(void);
 
 #define __put_user_size(x, ptr, size, label)				\
 do {									\
+	__typeof__(*(ptr)) __pus_val = x;				\
 	__chk_user_ptr(ptr);						\
+	instrument_copy_to_user(ptr, &(__pus_val), size);		\
 	switch (size) {							\
 	case 1:								\
 		__put_user_goto(x, ptr, "b", "iq", label);		\
@@ -313,6 +318,7 @@ do {									\
 #define __get_user_size(x, ptr, size, label)				\
 do {									\
 	__chk_user_ptr(ptr);						\
+	instrument_copy_from_user_before((void *)&(x), ptr, size);	\
 	switch (size) {							\
 	unsigned char x_u8__;						\
 	case 1:								\
@@ -331,6 +337,7 @@ do {									\
 	default:							\
 		(x) = __get_user_bad();					\
 	}								\
+	instrument_copy_from_user_after((void *)&(x), ptr, size, 0);	\
 } while (0)
 
 #define __get_user_asm(x, addr, itype, ltype, label)			\
-- 
2.34.1.173.g76aa8bc2d0-goog