1//===-- options.inc ---------------------------------------------*- C++ -*-===// 2// 3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4// See https://llvm.org/LICENSE.txt for license information. 5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6// 7//===----------------------------------------------------------------------===// 8 9#ifndef GWP_ASAN_OPTION 10#error "Define GWP_ASAN_OPTION prior to including this file!" 11#endif 12 13#ifndef GWP_ASAN_DEFAULT_ENABLED 14#define GWP_ASAN_DEFAULT_ENABLED true 15#endif 16 17#ifndef GWP_ASAN_STRINGIFY 18#define GWP_ASAN_STRINGIFY(S) GWP_ASAN_STRINGIFY_(S) 19#define GWP_ASAN_STRINGIFY_(S) #S 20#endif 21 22GWP_ASAN_OPTION(bool, Enabled, GWP_ASAN_DEFAULT_ENABLED, 23 "Is GWP-ASan enabled? Defaults to " GWP_ASAN_STRINGIFY( 24 GWP_ASAN_DEFAULT_ENABLED) ".") 25 26GWP_ASAN_OPTION( 27 bool, PerfectlyRightAlign, false, 28 "When allocations are right-aligned, should we perfectly align them up to " 29 "the page boundary? By default (false), we round up allocation size to the " 30 "nearest power of two (1, 2, 4, 8, 16) up to a maximum of 16-byte " 31 "alignment for performance reasons. For Bionic, we use 8-byte alignment by " 32 "default. Setting this to true can find single byte buffer-overflows for " 33 "multibyte allocations at the cost of performance, and may be incompatible " 34 "with some architectures.") 35 36GWP_ASAN_OPTION(int, MaxSimultaneousAllocations, 16, 37 "Number of simultaneously-guarded allocations available in the " 38 "pool. Defaults to 16.") 39 40GWP_ASAN_OPTION(int, SampleRate, 5000, 41 "The probability (1 / SampleRate) that an allocation is " 42 "selected for GWP-ASan sampling. Default is 5000. Sample rates " 43 "up to (2^30 - 1) are supported.") 44 45// Developer note - This option is not actually processed by GWP-ASan itself. It 46// is included here so that a user can specify whether they want signal handlers 47// or not. The supporting allocator should inspect this value to see whether 48// signal handlers need to be installed, and then use 49// crash_handler::installSignalHandlers() in order to install the handlers. Note 50// that in order to support signal handlers, you will need to link against the 51// optional crash_handler component. 52GWP_ASAN_OPTION( 53 bool, InstallSignalHandlers, true, 54 "Install GWP-ASan signal handlers for SIGSEGV during dynamic loading. This " 55 "allows better error reports by providing stack traces for allocation and " 56 "deallocation when reporting a memory error. GWP-ASan's signal handler " 57 "will forward the signal to any previously-installed handler, and user " 58 "programs that install further signal handlers should make sure they do " 59 "the same. Note, if the previously installed SIGSEGV handler is SIG_IGN, " 60 "we terminate the process after dumping the error report.") 61 62GWP_ASAN_OPTION(bool, InstallForkHandlers, true, 63 "Install GWP-ASan atfork handlers to acquire internal locks " 64 "before fork and release them after.") 65 66GWP_ASAN_OPTION(bool, help, false, "Print a summary of the available options.") 67 68// ============================================================================= 69// ==== WARNING 70// ============================================================================= 71// If you are adding flags to GWP-ASan, please note that GWP-ASan flag strings 72// may be parsed by trusted system components (on Android, GWP-ASan flag strings 73// are parsed by libc during the dynamic loader). This means that GWP-ASan 74// should never feature flags like log paths on disk, because this can lead to 75// arbitrary file write and thus privilege escalation. For an example, see the 76// setuid ASan log_path exploits: https://www.exploit-db.com/exploits/46241. 77// 78// Please place all new flags above this warning, so that the warning always 79// stays at the bottom. 80