1//===-- asan_linux.cc -----------------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file is a part of AddressSanitizer, an address sanity checker.
11//
12// Linux-specific details.
13//===----------------------------------------------------------------------===//
14
15#include "sanitizer_common/sanitizer_platform.h"
16#if SANITIZER_FREEBSD || SANITIZER_LINUX
17
18#include "asan_interceptors.h"
19#include "asan_internal.h"
20#include "asan_thread.h"
21#include "sanitizer_common/sanitizer_flags.h"
22#include "sanitizer_common/sanitizer_freebsd.h"
23#include "sanitizer_common/sanitizer_libc.h"
24#include "sanitizer_common/sanitizer_procmaps.h"
25
26#include <sys/time.h>
27#include <sys/resource.h>
28#include <sys/mman.h>
29#include <sys/syscall.h>
30#include <sys/types.h>
31#include <dlfcn.h>
32#include <fcntl.h>
33#include <pthread.h>
34#include <stdio.h>
35#include <unistd.h>
36#include <unwind.h>
37
38#if SANITIZER_FREEBSD
39#include <sys/link_elf.h>
40#endif
41
42#if SANITIZER_ANDROID || SANITIZER_FREEBSD
43#include <ucontext.h>
44extern "C" void* _DYNAMIC;
45#else
46#include <sys/ucontext.h>
47#include <link.h>
48#endif
49
50// x86-64 FreeBSD 9.2 and older define 'ucontext_t' incorrectly in
51// 32-bit mode.
52#if SANITIZER_FREEBSD && (SANITIZER_WORDSIZE == 32) && \
53  __FreeBSD_version <= 902001  // v9.2
54#define ucontext_t xucontext_t
55#endif
56
57typedef enum {
58  ASAN_RT_VERSION_UNDEFINED = 0,
59  ASAN_RT_VERSION_DYNAMIC,
60  ASAN_RT_VERSION_STATIC,
61} asan_rt_version_t;
62
63// FIXME: perhaps also store abi version here?
64extern "C" {
65SANITIZER_INTERFACE_ATTRIBUTE
66asan_rt_version_t  __asan_rt_version;
67}
68
69namespace __asan {
70
71void InitializePlatformInterceptors() {}
72
73void DisableReexec() {
74  // No need to re-exec on Linux.
75}
76
77void MaybeReexec() {
78  // No need to re-exec on Linux.
79}
80
81void *AsanDoesNotSupportStaticLinkage() {
82  // This will fail to link with -static.
83  return &_DYNAMIC;  // defined in link.h
84}
85
86#if SANITIZER_ANDROID
87// FIXME: should we do anything for Android?
88void AsanCheckDynamicRTPrereqs() {}
89void AsanCheckIncompatibleRT() {}
90#else
91static int FindFirstDSOCallback(struct dl_phdr_info *info, size_t size,
92                                void *data) {
93  // Continue until the first dynamic library is found
94  if (!info->dlpi_name || info->dlpi_name[0] == 0)
95    return 0;
96
97  // Ignore vDSO
98  if (internal_strncmp(info->dlpi_name, "linux-", sizeof("linux-") - 1) == 0)
99    return 0;
100
101  *(const char **)data = info->dlpi_name;
102  return 1;
103}
104
105static bool IsDynamicRTName(const char *libname) {
106  return internal_strstr(libname, "libclang_rt.asan") ||
107    internal_strstr(libname, "libasan.so");
108}
109
110static void ReportIncompatibleRT() {
111  Report("Your application is linked against incompatible ASan runtimes.\n");
112  Die();
113}
114
115void AsanCheckDynamicRTPrereqs() {
116  // Ensure that dynamic RT is the first DSO in the list
117  const char *first_dso_name = 0;
118  dl_iterate_phdr(FindFirstDSOCallback, &first_dso_name);
119  if (first_dso_name && !IsDynamicRTName(first_dso_name)) {
120    Report("ASan runtime does not come first in initial library list; "
121           "you should either link runtime to your application or "
122           "manually preload it with LD_PRELOAD.\n");
123    Die();
124  }
125}
126
127void AsanCheckIncompatibleRT() {
128  if (ASAN_DYNAMIC) {
129    if (__asan_rt_version == ASAN_RT_VERSION_UNDEFINED) {
130      __asan_rt_version = ASAN_RT_VERSION_DYNAMIC;
131    } else if (__asan_rt_version != ASAN_RT_VERSION_DYNAMIC) {
132      ReportIncompatibleRT();
133    }
134  } else {
135    if (__asan_rt_version == ASAN_RT_VERSION_UNDEFINED) {
136      // Ensure that dynamic runtime is not present. We should detect it
137      // as early as possible, otherwise ASan interceptors could bind to
138      // the functions in dynamic ASan runtime instead of the functions in
139      // system libraries, causing crashes later in ASan initialization.
140      MemoryMappingLayout proc_maps(/*cache_enabled*/true);
141      char filename[128];
142      while (proc_maps.Next(0, 0, 0, filename, sizeof(filename), 0)) {
143        if (IsDynamicRTName(filename)) {
144          Report("Your application is linked against "
145                 "incompatible ASan runtimes.\n");
146          Die();
147        }
148      }
149      __asan_rt_version = ASAN_RT_VERSION_STATIC;
150    } else if (__asan_rt_version != ASAN_RT_VERSION_STATIC) {
151      ReportIncompatibleRT();
152    }
153  }
154}
155#endif  // SANITIZER_ANDROID
156
157void AsanPlatformThreadInit() {
158  // Nothing here for now.
159}
160
161#if !SANITIZER_ANDROID
162void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
163  ucontext_t *ucp = (ucontext_t*)context;
164  *stack = (uptr)ucp->uc_stack.ss_sp;
165  *ssize = ucp->uc_stack.ss_size;
166}
167#else
168void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
169  UNIMPLEMENTED();
170}
171#endif
172
173void *AsanDlSymNext(const char *sym) {
174  return dlsym(RTLD_NEXT, sym);
175}
176
177}  // namespace __asan
178
179#endif  // SANITIZER_FREEBSD || SANITIZER_LINUX
180