1 //===-- asan_linux.cpp ----------------------------------------------------===// 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 // This file is a part of AddressSanitizer, an address sanity checker. 10 // 11 // Linux-specific details. 12 //===----------------------------------------------------------------------===// 13 14 #include "sanitizer_common/sanitizer_platform.h" 15 #if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || \ 16 SANITIZER_SOLARIS 17 18 #include "asan_interceptors.h" 19 #include "asan_internal.h" 20 #include "asan_premap_shadow.h" 21 #include "asan_thread.h" 22 #include "sanitizer_common/sanitizer_flags.h" 23 #include "sanitizer_common/sanitizer_freebsd.h" 24 #include "sanitizer_common/sanitizer_libc.h" 25 #include "sanitizer_common/sanitizer_procmaps.h" 26 27 #include <sys/time.h> 28 #include <sys/resource.h> 29 #include <sys/mman.h> 30 #include <sys/syscall.h> 31 #include <sys/types.h> 32 #include <dlfcn.h> 33 #include <fcntl.h> 34 #include <limits.h> 35 #include <pthread.h> 36 #include <stdio.h> 37 #include <unistd.h> 38 #include <unwind.h> 39 40 #if SANITIZER_FREEBSD 41 #include <sys/link_elf.h> 42 #endif 43 44 #if SANITIZER_SOLARIS 45 #include <link.h> 46 #endif 47 48 #if SANITIZER_ANDROID || SANITIZER_FREEBSD || SANITIZER_SOLARIS 49 #include <ucontext.h> 50 extern "C" void* _DYNAMIC; 51 #elif SANITIZER_NETBSD 52 #include <link_elf.h> 53 #include <ucontext.h> 54 extern Elf_Dyn _DYNAMIC; 55 #else 56 #include <sys/ucontext.h> 57 #include <link.h> 58 extern ElfW(Dyn) _DYNAMIC[]; 59 #endif 60 61 // x86-64 FreeBSD 9.2 and older define 'ucontext_t' incorrectly in 62 // 32-bit mode. 63 #if SANITIZER_FREEBSD && (SANITIZER_WORDSIZE == 32) && \ 64 __FreeBSD_version <= 902001 // v9.2 65 #define ucontext_t xucontext_t 66 #endif 67 68 typedef enum { 69 ASAN_RT_VERSION_UNDEFINED = 0, 70 ASAN_RT_VERSION_DYNAMIC, 71 ASAN_RT_VERSION_STATIC, 72 } asan_rt_version_t; 73 74 // FIXME: perhaps also store abi version here? 75 extern "C" { 76 SANITIZER_INTERFACE_ATTRIBUTE 77 asan_rt_version_t __asan_rt_version; 78 } 79 80 namespace __asan { 81 82 void InitializePlatformInterceptors() {} 83 void InitializePlatformExceptionHandlers() {} 84 bool IsSystemHeapAddress (uptr addr) { return false; } 85 86 void *AsanDoesNotSupportStaticLinkage() { 87 // This will fail to link with -static. 88 return &_DYNAMIC; 89 } 90 91 #if ASAN_PREMAP_SHADOW 92 uptr FindPremappedShadowStart(uptr shadow_size_bytes) { 93 uptr granularity = GetMmapGranularity(); 94 uptr shadow_start = reinterpret_cast<uptr>(&__asan_shadow); 95 uptr premap_shadow_size = PremapShadowSize(); 96 uptr shadow_size = RoundUpTo(shadow_size_bytes, granularity); 97 // We may have mapped too much. Release extra memory. 98 UnmapFromTo(shadow_start + shadow_size, shadow_start + premap_shadow_size); 99 return shadow_start; 100 } 101 #endif 102 103 uptr FindDynamicShadowStart() { 104 uptr shadow_size_bytes = MemToShadowSize(kHighMemEnd); 105 #if ASAN_PREMAP_SHADOW 106 if (!PremapShadowFailed()) 107 return FindPremappedShadowStart(shadow_size_bytes); 108 #endif 109 110 return MapDynamicShadow(shadow_size_bytes, SHADOW_SCALE, 111 /*min_shadow_base_alignment*/ 0, kHighMemEnd); 112 } 113 114 void AsanApplyToGlobals(globals_op_fptr op, const void *needle) { 115 UNIMPLEMENTED(); 116 } 117 118 void FlushUnneededASanShadowMemory(uptr p, uptr size) { 119 // Since asan's mapping is compacting, the shadow chunk may be 120 // not page-aligned, so we only flush the page-aligned portion. 121 ReleaseMemoryPagesToOS(MemToShadow(p), MemToShadow(p + size)); 122 } 123 124 #if SANITIZER_ANDROID 125 // FIXME: should we do anything for Android? 126 void AsanCheckDynamicRTPrereqs() {} 127 void AsanCheckIncompatibleRT() {} 128 #else 129 static int FindFirstDSOCallback(struct dl_phdr_info *info, size_t size, 130 void *data) { 131 VReport(2, "info->dlpi_name = %s\tinfo->dlpi_addr = %p\n", 132 info->dlpi_name, info->dlpi_addr); 133 134 // Continue until the first dynamic library is found 135 if (!info->dlpi_name || info->dlpi_name[0] == 0) 136 return 0; 137 138 // Ignore vDSO 139 if (internal_strncmp(info->dlpi_name, "linux-", sizeof("linux-") - 1) == 0) 140 return 0; 141 142 #if SANITIZER_FREEBSD || SANITIZER_NETBSD 143 // Ignore first entry (the main program) 144 char **p = (char **)data; 145 if (!(*p)) { 146 *p = (char *)-1; 147 return 0; 148 } 149 #endif 150 151 #if SANITIZER_SOLARIS 152 // Ignore executable on Solaris 153 if (info->dlpi_addr == 0) 154 return 0; 155 #endif 156 157 *(const char **)data = info->dlpi_name; 158 return 1; 159 } 160 161 static bool IsDynamicRTName(const char *libname) { 162 return internal_strstr(libname, "libclang_rt.asan") || 163 internal_strstr(libname, "libasan.so"); 164 } 165 166 static void ReportIncompatibleRT() { 167 Report("Your application is linked against incompatible ASan runtimes.\n"); 168 Die(); 169 } 170 171 void AsanCheckDynamicRTPrereqs() { 172 if (!ASAN_DYNAMIC || !flags()->verify_asan_link_order) 173 return; 174 175 // Ensure that dynamic RT is the first DSO in the list 176 const char *first_dso_name = nullptr; 177 dl_iterate_phdr(FindFirstDSOCallback, &first_dso_name); 178 if (first_dso_name && !IsDynamicRTName(first_dso_name)) { 179 Report("ASan runtime does not come first in initial library list; " 180 "you should either link runtime to your application or " 181 "manually preload it with LD_PRELOAD.\n"); 182 Die(); 183 } 184 } 185 186 void AsanCheckIncompatibleRT() { 187 if (ASAN_DYNAMIC) { 188 if (__asan_rt_version == ASAN_RT_VERSION_UNDEFINED) { 189 __asan_rt_version = ASAN_RT_VERSION_DYNAMIC; 190 } else if (__asan_rt_version != ASAN_RT_VERSION_DYNAMIC) { 191 ReportIncompatibleRT(); 192 } 193 } else { 194 if (__asan_rt_version == ASAN_RT_VERSION_UNDEFINED) { 195 // Ensure that dynamic runtime is not present. We should detect it 196 // as early as possible, otherwise ASan interceptors could bind to 197 // the functions in dynamic ASan runtime instead of the functions in 198 // system libraries, causing crashes later in ASan initialization. 199 MemoryMappingLayout proc_maps(/*cache_enabled*/true); 200 char filename[PATH_MAX]; 201 MemoryMappedSegment segment(filename, sizeof(filename)); 202 while (proc_maps.Next(&segment)) { 203 if (IsDynamicRTName(segment.filename)) { 204 Report("Your application is linked against " 205 "incompatible ASan runtimes.\n"); 206 Die(); 207 } 208 } 209 __asan_rt_version = ASAN_RT_VERSION_STATIC; 210 } else if (__asan_rt_version != ASAN_RT_VERSION_STATIC) { 211 ReportIncompatibleRT(); 212 } 213 } 214 } 215 #endif // SANITIZER_ANDROID 216 217 #if !SANITIZER_ANDROID 218 void ReadContextStack(void *context, uptr *stack, uptr *ssize) { 219 ucontext_t *ucp = (ucontext_t*)context; 220 *stack = (uptr)ucp->uc_stack.ss_sp; 221 *ssize = ucp->uc_stack.ss_size; 222 } 223 #else 224 void ReadContextStack(void *context, uptr *stack, uptr *ssize) { 225 UNIMPLEMENTED(); 226 } 227 #endif 228 229 void *AsanDlSymNext(const char *sym) { 230 return dlsym(RTLD_NEXT, sym); 231 } 232 233 bool HandleDlopenInit() { 234 // Not supported on this platform. 235 static_assert(!SANITIZER_SUPPORTS_INIT_FOR_DLOPEN, 236 "Expected SANITIZER_SUPPORTS_INIT_FOR_DLOPEN to be false"); 237 return false; 238 } 239 240 } // namespace __asan 241 242 #endif // SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || 243 // SANITIZER_SOLARIS 244