1.\" $NetBSD: kernel_sanitizers.7,v 1.6 2020/07/12 13:40:44 skrll Exp $ 2.\" 3.\" Copyright (c) 2020 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Maxime Villard. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd July 12, 2020 31.Dt KERNEL_SANITIZERS 7 32.Os 33.Sh NAME 34.Nm kernel_sanitizers 35.Nd NetBSD Kernel Sanitizers 36.Sh DESCRIPTION 37Kernel Sanitizers are powerful kernel bug detection features that can 38automatically discover several classes of bugs at run time while the kernel 39executes. 40.Pp 41.Nx 42supports four kernel sanitizers. 43They are not mutually compatible, and only one can be enabled at a time, via 44compilation options. 45.Sh KUBSAN 46Kernel Undefined Behavior Sanitizer, specializes in finding several types of 47undefined behaviors, such a misaligned accesses and integer overflows. 48.Ss Runtime cost 49Heavy runtime checks. 50.Ss Used components 51Compiler instrumentation and an entirely MI runtime. 52.Ss Supported architectures 53aarch64 (gcc), amd64 (gcc), arm (gcc). 54[Theoretically supported on all other architectures with no MD change required] 55.Ss Files 56.Bl -tag -width XXXX -compact 57.It Pa src/common/lib/libc/misc/ubsan.c 58Core KUBSAN code. 59MI. 60.El 61.Sh KASAN 62Kernel Address Sanitizer, specializes in finding memory corruptions such as 63buffer overflows and use-after-frees. 64.Ss Runtime cost 65Heavy runtime checks, and ~12.5% increase in memory consumption. 66.Ss Used components 67Shadow memory, compiler instrumentation, special kernel wrappers, and 68light MD infrastructure. 69.Ss Supported architectures 70aarch64 (gcc), amd64 (gcc, llvm), arm (gcc). 71.Pp 72KASAN is made of six sub-features that perform memory validation: 73.Bd -literal 74 +-----------------------------------------------------+ 75 | SUPPORTED SUB-FEATURE | 76+---------+------+-------+---------+-----------+---------+------+ 77| PORT | HEAP | STACK | ATOMICS | BUS_SPACE | BUS_DMA | VLAs | 78+---------+------+-------+---------+-----------+---------+------+ 79| amd64 | Yes | Yes | Yes | Yes | Yes | Yes | 80+---------+------+-------+---------+-----------+---------+------+ 81| aarch64 | Yes | Yes | Yes | No | Yes | Yes | 82+---------+------+-------+---------+-----------+---------+------+ 83| arm | Yes | Yes | Yes | No | Yes | Yes | 84+---------+------+-------+---------+-----------+---------+------+ 85.Ed 86.Pp 87An architecture is allowed to have only partial support. 88.Ss Files 89.Bl -tag -width XXXX -compact 90.It Pa src/sys/kern/subr_asan.c 91Core KASAN code. 92MI. 93.It Pa src/sys/sys/asan.h 94Main KASAN header. 95MI. 96.It Pa src/sys/arch/{port}/include/asan.h 97Port-specific KASAN code. 98MD. 99.El 100.Pp 101Each new port of KASAN should respect the existing naming conventions, and 102should introduce only one MD header file. 103.Sh KCSAN 104Kernel Concurrency Sanitizer, specializes in finding memory races. 105.Ss Runtime cost 106Medium runtime checks. 107.Ss Used components 108Compiler instrumentation, special kernel wrappers, and light MD infrastructure. 109.Ss Supported architectures 110amd64 (gcc). 111.Ss Files 112.Bl -tag -width XXXX -compact 113.It Pa src/sys/kern/subr_csan.c 114Core KCSAN code. 115MI. 116.It Pa src/sys/sys/csan.h 117Main KCSAN header. 118MI. 119.It Pa src/sys/arch/{port}/include/csan.h 120Port-specific KCSAN code. 121MD. 122.El 123.Pp 124Each new port of KCSAN should respect the existing naming conventions, and 125should introduce only one MD header file. 126.Sh KMSAN 127Kernel Memory Sanitizer, specializes in finding uninitialized memory. 128.Ss Runtime cost 129Heavy runtime checks, and ~200% increase in memory consumption. 130.Ss Used components 131Double shadow memory, compiler instrumentation, special kernel wrappers, and 132heavy MD infrastructure. 133.Ss Supported architectures 134amd64 (llvm). 135.Ss Files 136.Bl -tag -width XXXX -compact 137.It Pa src/sys/kern/subr_msan.c 138Core KMSAN code. 139MI. 140.It Pa src/sys/sys/msan.h 141Main KMSAN header. 142MI. 143.It Pa src/sys/arch/{port}/include/msan.h 144Port-specific KMSAN code. 145MD. 146.El 147.Pp 148Each new port of KMSAN should respect the existing naming conventions, and 149should introduce only one MD header file. 150.Sh AUTHORS 151.An -nosplit 152Support for KUBSAN was developed by 153.An Kamil Rytarowski . 154Support for KASAN, KCSAN and KMSAN was developed by 155.An Maxime Villard . 156Support for KASAN on ARM was developed by 157.An Nick Hudson . 158