dlfcn.cpp revision 5e2285d3ccdbb64a49ad2e5e521f50c897a3954d 
1/*
2 * Copyright (C) 2007 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *  * Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 *  * Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in
12 *    the documentation and/or other materials provided with the
13 *    distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include "linker.h"
30#include "linker_cfi.h"
31#include "linker_globals.h"
32#include "linker_dlwarning.h"
33
34#include <pthread.h>
35#include <stdio.h>
36#include <stdlib.h>
37#include <string.h>
38#include <android/api-level.h>
39
40#include <bionic/pthread_internal.h>
41#include "private/bionic_tls.h"
42#include "private/ScopedPthreadMutexLocker.h"
43
44static pthread_mutex_t g_dl_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
45
46static char* __bionic_set_dlerror(char* new_value) {
47  char** dlerror_slot = &reinterpret_cast<char**>(__get_tls())[TLS_SLOT_DLERROR];
48
49  char* old_value = *dlerror_slot;
50  *dlerror_slot = new_value;
51  return old_value;
52}
53
54static void __bionic_format_dlerror(const char* msg, const char* detail) {
55  char* buffer = __get_thread()->dlerror_buffer;
56  strlcpy(buffer, msg, __BIONIC_DLERROR_BUFFER_SIZE);
57  if (detail != nullptr) {
58    strlcat(buffer, ": ", __BIONIC_DLERROR_BUFFER_SIZE);
59    strlcat(buffer, detail, __BIONIC_DLERROR_BUFFER_SIZE);
60  }
61
62  __bionic_set_dlerror(buffer);
63}
64
65char* __dlerror() {
66  char* old_value = __bionic_set_dlerror(nullptr);
67  return old_value;
68}
69
70void __android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size) {
71  ScopedPthreadMutexLocker locker(&g_dl_mutex);
72  do_android_get_LD_LIBRARY_PATH(buffer, buffer_size);
73}
74
75void __android_update_LD_LIBRARY_PATH(const char* ld_library_path) {
76  ScopedPthreadMutexLocker locker(&g_dl_mutex);
77  do_android_update_LD_LIBRARY_PATH(ld_library_path);
78}
79
80static void* dlopen_ext(const char* filename,
81                        int flags,
82                        const android_dlextinfo* extinfo,
83                        const void* caller_addr) {
84  ScopedPthreadMutexLocker locker(&g_dl_mutex);
85  g_linker_logger.ResetState();
86  void* result = do_dlopen(filename, flags, extinfo, caller_addr);
87  if (result == nullptr) {
88    __bionic_format_dlerror("dlopen failed", linker_get_error_buffer());
89    return nullptr;
90  }
91  return result;
92}
93
94void* __android_dlopen_ext(const char* filename,
95                           int flags,
96                           const android_dlextinfo* extinfo,
97                           const void* caller_addr) {
98  return dlopen_ext(filename, flags, extinfo, caller_addr);
99}
100
101void* __dlopen(const char* filename, int flags, const void* caller_addr) {
102  return dlopen_ext(filename, flags, nullptr, caller_addr);
103}
104
105void* dlsym_impl(void* handle, const char* symbol, const char* version, const void* caller_addr) {
106  ScopedPthreadMutexLocker locker(&g_dl_mutex);
107  g_linker_logger.ResetState();
108  void* result;
109  if (!do_dlsym(handle, symbol, version, caller_addr, &result)) {
110    __bionic_format_dlerror(linker_get_error_buffer(), nullptr);
111    return nullptr;
112  }
113
114  return result;
115}
116
117void* __dlsym(void* handle, const char* symbol, const void* caller_addr) {
118  return dlsym_impl(handle, symbol, nullptr, caller_addr);
119}
120
121void* __dlvsym(void* handle, const char* symbol, const char* version, const void* caller_addr) {
122  return dlsym_impl(handle, symbol, version, caller_addr);
123}
124
125int __dladdr(const void* addr, Dl_info* info) {
126  ScopedPthreadMutexLocker locker(&g_dl_mutex);
127  return do_dladdr(addr, info);
128}
129
130int __dlclose(void* handle) {
131  ScopedPthreadMutexLocker locker(&g_dl_mutex);
132  int result = do_dlclose(handle);
133  if (result != 0) {
134    __bionic_format_dlerror("dlclose failed", linker_get_error_buffer());
135  }
136  return result;
137}
138
139// This function is needed by libgcc.a (this is why there is no prefix for this one)
140int dl_iterate_phdr(int (*cb)(dl_phdr_info* info, size_t size, void* data), void* data) {
141  ScopedPthreadMutexLocker locker(&g_dl_mutex);
142  return do_dl_iterate_phdr(cb, data);
143}
144
145#if defined(__arm__)
146_Unwind_Ptr __dl_unwind_find_exidx(_Unwind_Ptr pc, int* pcount) {
147  ScopedPthreadMutexLocker locker(&g_dl_mutex);
148  return do_dl_unwind_find_exidx(pc, pcount);
149}
150#endif
151
152void __android_set_application_target_sdk_version(uint32_t target) {
153  // lock to avoid modification in the middle of dlopen.
154  ScopedPthreadMutexLocker locker(&g_dl_mutex);
155  set_application_target_sdk_version(target);
156}
157
158uint32_t __android_get_application_target_sdk_version() {
159  return get_application_target_sdk_version();
160}
161
162void __android_dlwarning(void* obj, void (*f)(void*, const char*)) {
163  ScopedPthreadMutexLocker locker(&g_dl_mutex);
164  get_dlwarning(obj, f);
165}
166
167bool __android_init_anonymous_namespace(const char* shared_libs_sonames,
168                                         const char* library_search_path) {
169  ScopedPthreadMutexLocker locker(&g_dl_mutex);
170  bool success = init_anonymous_namespace(shared_libs_sonames, library_search_path);
171  if (!success) {
172    __bionic_format_dlerror("android_init_anonymous_namespace failed", linker_get_error_buffer());
173  }
174
175  return success;
176}
177
178android_namespace_t* __android_create_namespace(const char* name,
179                                                const char* ld_library_path,
180                                                const char* default_library_path,
181                                                uint64_t type,
182                                                const char* permitted_when_isolated_path,
183                                                android_namespace_t* parent_namespace,
184                                                const void* caller_addr) {
185  ScopedPthreadMutexLocker locker(&g_dl_mutex);
186
187  android_namespace_t* result = create_namespace(caller_addr,
188                                                 name,
189                                                 ld_library_path,
190                                                 default_library_path,
191                                                 type,
192                                                 permitted_when_isolated_path,
193                                                 parent_namespace);
194
195  if (result == nullptr) {
196    __bionic_format_dlerror("android_create_namespace failed", linker_get_error_buffer());
197  }
198
199  return result;
200}
201
202bool __android_link_namespaces(android_namespace_t* namespace_from,
203                               android_namespace_t* namespace_to,
204                               const char* shared_libs_sonames) {
205  ScopedPthreadMutexLocker locker(&g_dl_mutex);
206
207  bool success = link_namespaces(namespace_from, namespace_to, shared_libs_sonames);
208
209  if (!success) {
210    __bionic_format_dlerror("android_link_namespaces failed", linker_get_error_buffer());
211  }
212
213  return success;
214}
215
216void __cfi_fail(uint64_t CallSiteTypeId, void* Ptr, void *DiagData, void *CallerPc) {
217  CFIShadowWriter::CfiFail(CallSiteTypeId, Ptr, DiagData, CallerPc);
218}
219
220// name_offset: starting index of the name in libdl_info.strtab
221#define ELF32_SYM_INITIALIZER(name_offset, value, shndx) \
222    { name_offset, \
223      reinterpret_cast<Elf32_Addr>(value), \
224      /* st_size */ 0, \
225      ((shndx) == 0) ? 0 : (STB_GLOBAL << 4), \
226      /* st_other */ 0, \
227      shndx, \
228    }
229
230#define ELF64_SYM_INITIALIZER(name_offset, value, shndx) \
231    { name_offset, \
232      ((shndx) == 0) ? 0 : (STB_GLOBAL << 4), \
233      /* st_other */ 0, \
234      shndx, \
235      reinterpret_cast<Elf64_Addr>(value), \
236      /* st_size */ 0, \
237    }
238
239static const char ANDROID_LIBDL_STRTAB[] =
240  // 0000000000111111 11112222222222333 333333344444444 44555555555566666 6666677777777778 8888888889999999999
241  // 0123456789012345 67890123456789012 345678901234567 89012345678901234 5678901234567890 1234567890123456789
242    "__loader_dlopen\0__loader_dlclose\0__loader_dlsym\0__loader_dlerror\0__loader_dladdr\0__loader_android_up"
243  // 1*
244  // 000000000011111111112 2222222223333333333444444444455555555 5566666666667777777777888 88888889999999999
245  // 012345678901234567890 1234567890123456789012345678901234567 8901234567890123456789012 34567890123456789
246    "date_LD_LIBRARY_PATH\0__loader_android_get_LD_LIBRARY_PATH\0__loader_dl_iterate_phdr\0__loader_android_"
247  // 2*
248  // 00000000001 1111111112222222222333333333344444444445555555555666 6666666777777777788888888889999999999
249  // 01234567890 1234567890123456789012345678901234567890123456789012 3456789012345678901234567890123456789
250    "dlopen_ext\0__loader_android_set_application_target_sdk_version\0__loader_android_get_application_targ"
251  // 3*
252  // 000000000011111 111112222222222333333333344444444445555555 5556666666666777777777788888888889 999999999
253  // 012345678901234 567890123456789012345678901234567890123456 7890123456789012345678901234567890 123456789
254    "et_sdk_version\0__loader_android_init_anonymous_namespace\0__loader_android_create_namespace\0__loader_"
255  // 4*
256  // 0000000 000111111111122222222223333 333333444444444455 555555556666666666777777777788888 888889999999999
257  // 0123456 789012345678901234567890123 456789012345678901 234567890123456789012345678901234 567890123456789
258    "dlvsym\0__loader_android_dlwarning\0__loader_cfi_fail\0__loader_android_link_namespaces\0"
259#if defined(__arm__)
260  // 485
261    "__loader_dl_unwind_find_exidx\0"
262#endif
263    ;
264
265static ElfW(Sym) g_libdl_symtab[] = {
266  // Total length of libdl_info.strtab, including trailing 0.
267  // This is actually the STH_UNDEF entry. Technically, it's
268  // supposed to have st_name == 0, but instead, it points to an index
269  // in the strtab with a \0 to make iterating through the symtab easier.
270  ELFW(SYM_INITIALIZER)(sizeof(ANDROID_LIBDL_STRTAB) - 1, nullptr, 0),
271  ELFW(SYM_INITIALIZER)(  0, &__dlopen, 1),
272  ELFW(SYM_INITIALIZER)( 16, &__dlclose, 1),
273  ELFW(SYM_INITIALIZER)( 33, &__dlsym, 1),
274  ELFW(SYM_INITIALIZER)( 48, &__dlerror, 1),
275  ELFW(SYM_INITIALIZER)( 65, &__dladdr, 1),
276  ELFW(SYM_INITIALIZER)( 81, &__android_update_LD_LIBRARY_PATH, 1),
277  ELFW(SYM_INITIALIZER)(121, &__android_get_LD_LIBRARY_PATH, 1),
278  ELFW(SYM_INITIALIZER)(158, &dl_iterate_phdr, 1),
279  ELFW(SYM_INITIALIZER)(183, &__android_dlopen_ext, 1),
280  ELFW(SYM_INITIALIZER)(211, &__android_set_application_target_sdk_version, 1),
281  ELFW(SYM_INITIALIZER)(263, &__android_get_application_target_sdk_version, 1),
282  ELFW(SYM_INITIALIZER)(315, &__android_init_anonymous_namespace, 1),
283  ELFW(SYM_INITIALIZER)(357, &__android_create_namespace, 1),
284  ELFW(SYM_INITIALIZER)(391, &__dlvsym, 1),
285  ELFW(SYM_INITIALIZER)(407, &__android_dlwarning, 1),
286  ELFW(SYM_INITIALIZER)(434, &__cfi_fail, 1),
287  ELFW(SYM_INITIALIZER)(452, &__android_link_namespaces, 1),
288#if defined(__arm__)
289  ELFW(SYM_INITIALIZER)(485, &__dl_unwind_find_exidx, 1),
290#endif
291};
292
293// Fake out a hash table with a single bucket.
294//
295// A search of the hash table will look through g_libdl_symtab starting with index 1, then
296// use g_libdl_chains to find the next index to look at. g_libdl_chains should be set up to
297// walk through every element in g_libdl_symtab, and then end with 0 (sentinel value).
298//
299// That is, g_libdl_chains should look like { 0, 2, 3, ... N, 0 } where N is the number
300// of actual symbols, or nelems(g_libdl_symtab)-1 (since the first element of g_libdl_symtab is not
301// a real symbol). (See soinfo_elf_lookup().)
302//
303// Note that adding any new symbols here requires stubbing them out in libdl.
304static unsigned g_libdl_buckets[1] = { 1 };
305#if defined(__arm__)
306static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 0 };
307#else
308static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 0 };
309#endif
310
311static uint8_t __libdl_info_buf[sizeof(soinfo)] __attribute__((aligned(8)));
312static soinfo* __libdl_info = nullptr;
313
314// This is used by the dynamic linker. Every process gets these symbols for free.
315soinfo* get_libdl_info(const char* linker_path) {
316  if (__libdl_info == nullptr) {
317    __libdl_info = new (__libdl_info_buf) soinfo(&g_default_namespace, linker_path, nullptr, 0, 0);
318    __libdl_info->flags_ |= FLAG_LINKED;
319    __libdl_info->strtab_ = ANDROID_LIBDL_STRTAB;
320    __libdl_info->symtab_ = g_libdl_symtab;
321    __libdl_info->nbucket_ = sizeof(g_libdl_buckets)/sizeof(unsigned);
322    __libdl_info->nchain_ = sizeof(g_libdl_chains)/sizeof(unsigned);
323    __libdl_info->bucket_ = g_libdl_buckets;
324    __libdl_info->chain_ = g_libdl_chains;
325    __libdl_info->ref_count_ = 1;
326    __libdl_info->strtab_size_ = sizeof(ANDROID_LIBDL_STRTAB);
327    __libdl_info->local_group_root_ = __libdl_info;
328    __libdl_info->soname_ = "ld-android.so";
329    __libdl_info->target_sdk_version_ = __ANDROID_API__;
330    __libdl_info->generate_handle();
331#if defined(__work_around_b_24465209__)
332    strlcpy(__libdl_info->old_name_, __libdl_info->soname_, sizeof(__libdl_info->old_name_));
333#endif
334  }
335
336  return __libdl_info;
337}
338