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[src/trunk]: src/sys Add support for Kernel Memory Sanitizer (kMSan). It dete...
details: https://anonhg.NetBSD.org/src/rev/58f11351c731
branches: trunk
changeset: 461070:58f11351c731
user: maxv <maxv%NetBSD.org@localhost>
date: Thu Nov 14 16:23:52 2019 +0000
description:
Add support for Kernel Memory Sanitizer (kMSan). It detects uninitialized
memory used by the kernel at run time, and just like kASan and kCSan, it
is an excellent feature. It has already detected 38 uninitialized variables
in the kernel during my testing, which I have since discreetly fixed.
We use two shadows:
- "shad", to track uninitialized memory with a bit granularity (1:1).
Each bit set to 1 in the shad corresponds to one uninitialized bit of
real kernel memory.
- "orig", to track the origin of the memory with a 4-byte granularity
(1:1). Each uint32_t cell in the orig indicates the origin of the
associated uint32_t of real kernel memory.
The memory consumption of these shadows is consequent, so at least 4GB of
RAM is recommended to run kMSan.
The compiler inserts calls to specific __msan_* functions on each memory
access, to manage both the shad and the orig and detect uninitialized
memory accesses that change the execution flow (like an "if" on an
uninitialized variable).
We mark as uninit several types of memory buffers (stack, pools, kmem,
malloc, uvm_km), and check each buffer passed to copyout, copyoutstr,
bwrite, if_transmit_lock and DMA operations, to detect uninitialized memory
that leaves the system. This allows us to detect kernel info leaks in a way
that is more efficient and also more user-friendly than KLEAK.
Contrary to kASan, kMSan requires comprehensive coverage, ie we cannot
tolerate having one non-instrumented function, because this could cause
false positives. kMSan cannot instrument ASM functions, so I converted
most of them to __asm__ inlines, which kMSan is able to instrument. Those
that remain receive special treatment.
Contrary to kASan again, kMSan uses a TLS, so we must context-switch this
TLS during interrupts. We use different contexts depending on the interrupt
level.
The orig tracks precisely the origin of a buffer. We use a special encoding
for the orig values, and pack together in each uint32_t cell of the orig:
- a code designating the type of memory (Stack, Pool, etc), and
- a compressed pointer, which points either (1) to a string containing
the name of the variable associated with the cell, or (2) to an area
in the kernel .text section which we resolve to a symbol name + offset.
This encoding allows us not to consume extra memory for associating
information with each cell, and produces a precise output, that can tell
for example the name of an uninitialized variable on the stack, the
function in which it was pushed on the stack, and the function where we
accessed this uninitialized variable.
kMSan is available with LLVM, but not with GCC.
The code is organized in a way that is similar to kASan and kCSan, so it
means that other architectures than amd64 can be supported.
diffstat:
sys/arch/amd64/amd64/amd64_trap.S | 6 +-
sys/arch/amd64/amd64/busfunc.S | 10 +-
sys/arch/amd64/amd64/cpu_in_cksum.S | 4 +-
sys/arch/amd64/amd64/cpufunc.S | 20 +-
sys/arch/amd64/amd64/lock_stubs.S | 3 +-
sys/arch/amd64/amd64/locore.S | 11 +-
sys/arch/amd64/amd64/machdep.c | 13 +-
sys/arch/amd64/amd64/mptramp.S | 5 +-
sys/arch/amd64/amd64/spl.S | 17 +-
sys/arch/amd64/conf/GENERIC | 15 +-
sys/arch/amd64/conf/Makefile.amd64 | 10 +-
sys/arch/amd64/include/cpu.h | 20 +-
sys/arch/amd64/include/frameasm.h | 69 +-
sys/arch/amd64/include/msan.h | 241 ++++++
sys/arch/amd64/include/param.h | 9 +-
sys/arch/amd64/include/pmap.h | 14 +-
sys/arch/amd64/include/types.h | 5 +-
sys/arch/x86/include/bus_defs.h | 5 +-
sys/arch/x86/include/pmap.h | 7 +-
sys/arch/x86/x86/bus_dma.c | 10 +-
sys/arch/x86/x86/pmap.c | 13 +-
sys/conf/files | 4 +-
sys/kern/files.kern | 3 +-
sys/kern/kern_lwp.c | 7 +-
sys/kern/kern_malloc.c | 17 +-
sys/kern/subr_kmem.c | 10 +-
sys/kern/subr_msan.c | 1356 +++++++++++++++++++++++++++++++++++
sys/kern/subr_pool.c | 55 +-
sys/lib/libkern/libkern.h | 19 +-
sys/net/if.c | 7 +-
sys/sys/atomic.h | 86 ++-
sys/sys/bus_proto.h | 55 +-
sys/sys/cdefs.h | 8 +-
sys/sys/lwp.h | 9 +-
sys/sys/msan.h | 85 ++
sys/sys/systm.h | 20 +-
sys/uvm/uvm_km.c | 11 +-
37 files changed, 2198 insertions(+), 61 deletions(-)
diffs (truncated from 3389 to 300 lines):
diff -r 9f92e6c7def6 -r 58f11351c731 sys/arch/amd64/amd64/amd64_trap.S
--- a/sys/arch/amd64/amd64/amd64_trap.S Thu Nov 14 13:58:22 2019 +0000
+++ b/sys/arch/amd64/amd64/amd64_trap.S Thu Nov 14 16:23:52 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: amd64_trap.S,v 1.49 2019/10/12 06:31:03 maxv Exp $ */
+/* $NetBSD: amd64_trap.S,v 1.50 2019/11/14 16:23:52 maxv Exp $ */
/*
* Copyright (c) 1998, 2007, 2008, 2017 The NetBSD Foundation, Inc.
@@ -224,6 +224,7 @@
cld
SMAP_ENABLE
IBRS_ENTER
+ KMSAN_ENTER
movw %gs,TF_GS(%rsp)
movw %fs,TF_FS(%rsp)
movw %es,TF_ES(%rsp)
@@ -267,6 +268,7 @@
movw %ds,TF_DS(%rsp)
SVS_ENTER_NMI
+ KMSAN_ENTER
movl $MSR_GSBASE,%ecx
rdmsr
@@ -292,6 +294,7 @@
IBRS_LEAVE
1:
+ KMSAN_LEAVE
SVS_LEAVE_NMI
INTR_RESTORE_GPRS
addq $TF_REGSIZE+16,%rsp
@@ -668,6 +671,7 @@
movl $T_ASTFLT,TF_TRAPNO(%rsp)
movq %rsp,%rdi
incq CPUVAR(NTRAP)
+ KMSAN_INIT_ARG(8)
call _C_LABEL(trap)
jmp .Lalltraps_checkast /* re-check ASTs */
3: CHECK_DEFERRED_SWITCH
diff -r 9f92e6c7def6 -r 58f11351c731 sys/arch/amd64/amd64/busfunc.S
--- a/sys/arch/amd64/amd64/busfunc.S Thu Nov 14 13:58:22 2019 +0000
+++ b/sys/arch/amd64/amd64/busfunc.S Thu Nov 14 16:23:52 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: busfunc.S,v 1.11 2013/06/22 05:20:57 uebayasi Exp $ */
+/* $NetBSD: busfunc.S,v 1.12 2019/11/14 16:23:52 maxv Exp $ */
/*-
* Copyright (c) 2007, 2008 The NetBSD Foundation, Inc.
@@ -30,6 +30,7 @@
*/
#include <machine/asm.h>
+#include <machine/frameasm.h>
#include "assym.h"
@@ -47,10 +48,12 @@
cmpl $X86_BUS_SPACE_IO, BST_TYPE(%rdi)
je 1f
movzbl (%rdx), %eax
+ KMSAN_INIT_RET(1)
ret
1:
xorl %eax, %eax
inb %dx, %al
+ KMSAN_INIT_RET(1)
ret
END(bus_space_read_1)
@@ -63,10 +66,12 @@
cmpl $X86_BUS_SPACE_IO, BST_TYPE(%rdi)
je 1f
movzwl (%rdx), %eax
+ KMSAN_INIT_RET(2)
ret
1:
xorl %eax, %eax
inw %dx, %ax
+ KMSAN_INIT_RET(2)
ret
END(bus_space_read_2)
@@ -79,9 +84,11 @@
cmpl $X86_BUS_SPACE_IO, BST_TYPE(%rdi)
je 1f
movl (%rdx), %eax
+ KMSAN_INIT_RET(4)
ret
1:
inl %dx, %eax
+ KMSAN_INIT_RET(4)
ret
END(bus_space_read_4)
@@ -94,6 +101,7 @@
cmpl $X86_BUS_SPACE_IO, BST_TYPE(%rdi)
je .Ldopanic
movq (%rdx), %rax
+ KMSAN_INIT_RET(8)
ret
END(bus_space_read_8)
diff -r 9f92e6c7def6 -r 58f11351c731 sys/arch/amd64/amd64/cpu_in_cksum.S
--- a/sys/arch/amd64/amd64/cpu_in_cksum.S Thu Nov 14 13:58:22 2019 +0000
+++ b/sys/arch/amd64/amd64/cpu_in_cksum.S Thu Nov 14 16:23:52 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: cpu_in_cksum.S,v 1.3 2015/06/30 21:08:24 christos Exp $ */
+/* $NetBSD: cpu_in_cksum.S,v 1.4 2019/11/14 16:23:52 maxv Exp $ */
/*-
* Copyright (c) 2008 Joerg Sonnenberger <joerg%NetBSD.org@localhost>.
@@ -30,6 +30,7 @@
*/
#include <machine/asm.h>
+#include <machine/frameasm.h>
#include "assym.h"
ENTRY(cpu_in_cksum)
@@ -282,6 +283,7 @@
.Mreturn:
popq %rbx
popq %rbp
+ KMSAN_INIT_RET(4)
ret
.Mout_of_mbufs:
diff -r 9f92e6c7def6 -r 58f11351c731 sys/arch/amd64/amd64/cpufunc.S
--- a/sys/arch/amd64/amd64/cpufunc.S Thu Nov 14 13:58:22 2019 +0000
+++ b/sys/arch/amd64/amd64/cpufunc.S Thu Nov 14 16:23:52 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: cpufunc.S,v 1.46 2019/10/30 17:06:57 maxv Exp $ */
+/* $NetBSD: cpufunc.S,v 1.47 2019/11/14 16:23:52 maxv Exp $ */
/*
* Copyright (c) 1998, 2007, 2008 The NetBSD Foundation, Inc.
@@ -153,6 +153,7 @@
ENTRY(x86_read_flags)
pushfq
popq %rax
+ KMSAN_INIT_RET(8)
ret
END(x86_read_flags)
@@ -174,6 +175,7 @@
addl CPUVAR(CC_SKEW), %eax
cmpq %rdi, L_NCSW(%rcx)
jne 2f
+ KMSAN_INIT_RET(4)
ret
2:
jmp 1b
@@ -194,6 +196,13 @@
xorq %rax, %rax
movq %rax, PCB_ONFAULT(%r8)
+#ifdef KMSAN
+ movq %rsi,%rdi
+ movq $8,%rsi
+ xorq %rdx,%rdx
+ callq _C_LABEL(kmsan_mark)
+#endif
+ KMSAN_INIT_RET(4)
ret
END(rdmsr_safe)
@@ -211,12 +220,14 @@
shlq $32, %rdx
orq %rdx, %rax
addq CPUVAR(CC_SKEW), %rax
+ KMSAN_INIT_RET(8)
ret
END(cpu_counter)
ENTRY(cpu_counter32)
rdtsc
addl CPUVAR(CC_SKEW), %eax
+ KMSAN_INIT_RET(4)
ret
END(cpu_counter32)
@@ -230,11 +241,13 @@
ENTRY(x86_curcpu)
movq %gs:(CPU_INFO_SELF), %rax
+ KMSAN_INIT_RET(8)
ret
END(x86_curcpu)
ENTRY(x86_curlwp)
movq %gs:(CPU_INFO_CURLWP), %rax
+ KMSAN_INIT_RET(8)
ret
END(x86_curlwp)
@@ -246,12 +259,14 @@
ENTRY(__byte_swap_u32_variable)
movl %edi, %eax
bswapl %eax
+ KMSAN_INIT_RET(4)
ret
END(__byte_swap_u32_variable)
ENTRY(__byte_swap_u16_variable)
movl %edi, %eax
xchgb %al, %ah
+ KMSAN_INIT_RET(2)
ret
END(__byte_swap_u16_variable)
@@ -330,6 +345,7 @@
movq %rdi, %rdx
xorq %rax, %rax
inb %dx, %al
+ KMSAN_INIT_RET(1)
ret
END(inb)
@@ -346,6 +362,7 @@
movq %rdi, %rdx
xorq %rax, %rax
inw %dx, %ax
+ KMSAN_INIT_RET(2)
ret
END(inw)
@@ -362,6 +379,7 @@
movq %rdi, %rdx
xorq %rax, %rax
inl %dx, %eax
+ KMSAN_INIT_RET(4)
ret
END(inl)
diff -r 9f92e6c7def6 -r 58f11351c731 sys/arch/amd64/amd64/lock_stubs.S
--- a/sys/arch/amd64/amd64/lock_stubs.S Thu Nov 14 13:58:22 2019 +0000
+++ b/sys/arch/amd64/amd64/lock_stubs.S Thu Nov 14 16:23:52 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: lock_stubs.S,v 1.32 2019/09/05 12:57:30 maxv Exp $ */
+/* $NetBSD: lock_stubs.S,v 1.33 2019/11/14 16:23:52 maxv Exp $ */
/*
* Copyright (c) 2006, 2007, 2008, 2009 The NetBSD Foundation, Inc.
@@ -343,6 +343,7 @@
cmpxchgb %ah, (%rdi)
movl $0, %eax
setz %al
+ KMSAN_INIT_RET(4)
RET
END(__cpu_simple_lock_try)
diff -r 9f92e6c7def6 -r 58f11351c731 sys/arch/amd64/amd64/locore.S
--- a/sys/arch/amd64/amd64/locore.S Thu Nov 14 13:58:22 2019 +0000
+++ b/sys/arch/amd64/amd64/locore.S Thu Nov 14 16:23:52 2019 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: locore.S,v 1.189 2019/10/12 06:31:03 maxv Exp $ */
+/* $NetBSD: locore.S,v 1.190 2019/11/14 16:23:52 maxv Exp $ */
/*
* Copyright-o-rama!
@@ -1235,6 +1235,7 @@
.Lswitch_return:
/* Return to the new LWP, returning 'oldlwp' in %rax. */
+ KMSAN_INIT_RET(8)
movq %r13,%rax
popq %r15
popq %r14
@@ -1321,6 +1322,7 @@
STI(si)
/* Pushed T_ASTFLT into tf_trapno on entry. */
movq %rsp,%rdi
+ KMSAN_INIT_ARG(8)
call _C_LABEL(trap)
jmp .Lsyscall_checkast /* re-check ASTs */
END(handle_syscall)
@@ -1336,8 +1338,10 @@
movq %rbp,%r14 /* for .Lsyscall_checkast */
movq %rax,%rdi
xorq %rbp,%rbp
+ KMSAN_INIT_ARG(16)
call _C_LABEL(lwp_startup)
movq %r13,%rdi
+ KMSAN_INIT_ARG(8)
call *%r12
jmp .Lsyscall_checkast
END(lwp_trampoline)
@@ -1410,6 +1414,7 @@
.if \is_svs
SVS_ENTER
.endif
+ KMSAN_ENTER
jmp handle_syscall
IDTVEC_END(\name)
.endm
@@ -1453,6 +1458,7 @@
TEXT_USER_BEGIN
_ALIGN_TEXT
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