1 /*
2 * Copyright (C) 2016 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 #pragma once
30
31 #include <link.h>
32
33 #include <memory>
34 #include <string>
35 #include <vector>
36
37 #include "private/bionic_elf_tls.h"
38 #include "linker_namespaces.h"
39 #include "linker_tls.h"
40
41 #define FLAG_LINKED 0x00000001
42 #define FLAG_EXE 0x00000004 // The main executable
43 #define FLAG_LINKER 0x00000010 // The linker itself
44 #define FLAG_GNU_HASH 0x00000040 // uses gnu hash
45 #define FLAG_MAPPED_BY_CALLER 0x00000080 // the map is reserved by the caller
46 // and should not be unmapped
47 #define FLAG_IMAGE_LINKED 0x00000100 // Is image linked - this is a guard on link_image.
48 // The difference between this flag and
49 // FLAG_LINKED is that FLAG_LINKED
50 // means is set when load_group is
51 // successfully loaded whereas this
52 // flag is set to avoid linking image
53 // when link_image called for the
54 // second time. This situation happens
55 // when load group is crossing
56 // namespace boundary twice and second
57 // local group depends on the same libraries.
58 #define FLAG_RESERVED 0x00000200 // This flag was set when there is at least one
59 // outstanding thread_local dtor
60 // registered with this soinfo. In such
61 // a case the actual unload is
62 // postponed until the last thread_local
63 // destructor associated with this
64 // soinfo is executed and this flag is
65 // unset.
66 #define FLAG_NEW_SOINFO 0x40000000 // new soinfo format
67
68 #define SOINFO_VERSION 5
69
70 typedef void (*linker_dtor_function_t)();
71 typedef void (*linker_ctor_function_t)(int, char**, char**);
72
73 class SymbolName {
74 public:
SymbolName(const char * name)75 explicit SymbolName(const char* name)
76 : name_(name), has_elf_hash_(false), has_gnu_hash_(false),
77 elf_hash_(0), gnu_hash_(0) { }
78
get_name()79 const char* get_name() {
80 return name_;
81 }
82
83 uint32_t elf_hash();
84 uint32_t gnu_hash();
85
86 private:
87 const char* name_;
88 bool has_elf_hash_;
89 bool has_gnu_hash_;
90 uint32_t elf_hash_;
91 uint32_t gnu_hash_;
92
93 DISALLOW_IMPLICIT_CONSTRUCTORS(SymbolName);
94 };
95
96 struct version_info {
version_infoversion_info97 constexpr version_info() : elf_hash(0), name(nullptr), target_si(nullptr) {}
98
99 uint32_t elf_hash;
100 const char* name;
101 const soinfo* target_si;
102 };
103
104 // TODO(dimitry): remove reference from soinfo member functions to this class.
105 class VersionTracker;
106
107 struct soinfo_tls {
108 TlsSegment segment;
109 size_t module_id = kTlsUninitializedModuleId;
110 };
111
112 #if defined(__work_around_b_24465209__)
113 #define SOINFO_NAME_LEN 128
114 #endif
115
116 struct soinfo {
117 #if defined(__work_around_b_24465209__)
118 private:
119 char old_name_[SOINFO_NAME_LEN];
120 #endif
121 public:
122 const ElfW(Phdr)* phdr;
123 size_t phnum;
124 #if defined(__work_around_b_24465209__)
125 ElfW(Addr) unused0; // DO NOT USE, maintained for compatibility.
126 #endif
127 ElfW(Addr) base;
128 size_t size;
129
130 #if defined(__work_around_b_24465209__)
131 uint32_t unused1; // DO NOT USE, maintained for compatibility.
132 #endif
133
134 ElfW(Dyn)* dynamic;
135
136 #if defined(__work_around_b_24465209__)
137 uint32_t unused2; // DO NOT USE, maintained for compatibility
138 uint32_t unused3; // DO NOT USE, maintained for compatibility
139 #endif
140
141 soinfo* next;
142 private:
143 uint32_t flags_;
144
145 const char* strtab_;
146 ElfW(Sym)* symtab_;
147
148 size_t nbucket_;
149 size_t nchain_;
150 uint32_t* bucket_;
151 uint32_t* chain_;
152
153 #if defined(__mips__) || !defined(__LP64__)
154 // This is only used by mips and mips64, but needs to be here for
155 // all 32-bit architectures to preserve binary compatibility.
156 ElfW(Addr)** plt_got_;
157 #endif
158
159 #if defined(USE_RELA)
160 ElfW(Rela)* plt_rela_;
161 size_t plt_rela_count_;
162
163 ElfW(Rela)* rela_;
164 size_t rela_count_;
165 #else
166 ElfW(Rel)* plt_rel_;
167 size_t plt_rel_count_;
168
169 ElfW(Rel)* rel_;
170 size_t rel_count_;
171 #endif
172
173 linker_ctor_function_t* preinit_array_;
174 size_t preinit_array_count_;
175
176 linker_ctor_function_t* init_array_;
177 size_t init_array_count_;
178 linker_dtor_function_t* fini_array_;
179 size_t fini_array_count_;
180
181 linker_ctor_function_t init_func_;
182 linker_dtor_function_t fini_func_;
183
184 #if defined(__arm__)
185 public:
186 // ARM EABI section used for stack unwinding.
187 uint32_t* ARM_exidx;
188 size_t ARM_exidx_count;
189 private:
190 #elif defined(__mips__)
191 uint32_t mips_symtabno_;
192 uint32_t mips_local_gotno_;
193 uint32_t mips_gotsym_;
194 bool mips_relocate_got(const VersionTracker& version_tracker,
195 const soinfo_list_t& global_group,
196 const soinfo_list_t& local_group);
197 #if !defined(__LP64__)
198 bool mips_check_and_adjust_fp_modes();
199 #endif
200 #endif
201 size_t ref_count_;
202 public:
203 link_map link_map_head;
204
205 bool constructors_called;
206
207 // When you read a virtual address from the ELF file, add this
208 // value to get the corresponding address in the process' address space.
209 ElfW(Addr) load_bias;
210
211 #if !defined(__LP64__)
212 bool has_text_relocations;
213 #endif
214 bool has_DT_SYMBOLIC;
215
216 public:
217 soinfo(android_namespace_t* ns, const char* name, const struct stat* file_stat,
218 off64_t file_offset, int rtld_flags);
219 ~soinfo();
220
221 void call_constructors();
222 void call_destructors();
223 void call_pre_init_constructors();
224 bool prelink_image();
225 bool link_image(const soinfo_list_t& global_group, const soinfo_list_t& local_group,
226 const android_dlextinfo* extinfo, size_t* relro_fd_offset);
227 bool protect_relro();
228
229 void add_child(soinfo* child);
230 void remove_all_links();
231
232 ino_t get_st_ino() const;
233 dev_t get_st_dev() const;
234 off64_t get_file_offset() const;
235
236 uint32_t get_rtld_flags() const;
237 uint32_t get_dt_flags_1() const;
238 void set_dt_flags_1(uint32_t dt_flags_1);
239
240 soinfo_list_t& get_children();
241 const soinfo_list_t& get_children() const;
242
243 soinfo_list_t& get_parents();
244
245 bool find_symbol_by_name(SymbolName& symbol_name,
246 const version_info* vi,
247 const ElfW(Sym)** symbol) const;
248
249 ElfW(Sym)* find_symbol_by_address(const void* addr);
250 ElfW(Addr) resolve_symbol_address(const ElfW(Sym)* s) const;
251
252 const char* get_string(ElfW(Word) index) const;
253 bool can_unload() const;
254 bool is_gnu_hash() const;
255
has_min_versionsoinfo256 bool inline has_min_version(uint32_t min_version __unused) const {
257 #if defined(__work_around_b_24465209__)
258 return (flags_ & FLAG_NEW_SOINFO) != 0 && version_ >= min_version;
259 #else
260 return true;
261 #endif
262 }
263
264 bool is_linked() const;
265 bool is_linker() const;
266 bool is_main_executable() const;
267
268 void set_linked();
269 void set_linker_flag();
270 void set_main_executable();
271 void set_nodelete();
272
273 size_t increment_ref_count();
274 size_t decrement_ref_count();
275 size_t get_ref_count() const;
276
277 soinfo* get_local_group_root() const;
278
279 void set_soname(const char* soname);
280 const char* get_soname() const;
281 const char* get_realpath() const;
282 const ElfW(Versym)* get_versym(size_t n) const;
283 ElfW(Addr) get_verneed_ptr() const;
284 size_t get_verneed_cnt() const;
285 ElfW(Addr) get_verdef_ptr() const;
286 size_t get_verdef_cnt() const;
287
288 int get_target_sdk_version() const;
289
290 void set_dt_runpath(const char *);
291 const std::vector<std::string>& get_dt_runpath() const;
292 android_namespace_t* get_primary_namespace();
293 void add_secondary_namespace(android_namespace_t* secondary_ns);
294 android_namespace_list_t& get_secondary_namespaces();
295
296 soinfo_tls* get_tls() const;
297
298 void set_mapped_by_caller(bool reserved_map);
299 bool is_mapped_by_caller() const;
300
301 uintptr_t get_handle() const;
302 void generate_handle();
303 void* to_handle();
304
305 private:
306 bool is_image_linked() const;
307 void set_image_linked();
308
309 bool elf_lookup(SymbolName& symbol_name, const version_info* vi, uint32_t* symbol_index) const;
310 ElfW(Sym)* elf_addr_lookup(const void* addr);
311 bool gnu_lookup(SymbolName& symbol_name, const version_info* vi, uint32_t* symbol_index) const;
312 ElfW(Sym)* gnu_addr_lookup(const void* addr);
313
314 bool lookup_version_info(const VersionTracker& version_tracker, ElfW(Word) sym,
315 const char* sym_name, const version_info** vi);
316
317 template<typename ElfRelIteratorT>
318 bool relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& rel_iterator,
319 const soinfo_list_t& global_group, const soinfo_list_t& local_group);
320 bool relocate_relr();
321 void apply_relr_reloc(ElfW(Addr) offset);
322
323 private:
324 // This part of the structure is only available
325 // when FLAG_NEW_SOINFO is set in this->flags.
326 uint32_t version_;
327
328 // version >= 0
329 dev_t st_dev_;
330 ino_t st_ino_;
331
332 // dependency graph
333 soinfo_list_t children_;
334 soinfo_list_t parents_;
335
336 // version >= 1
337 off64_t file_offset_;
338 uint32_t rtld_flags_;
339 uint32_t dt_flags_1_;
340 size_t strtab_size_;
341
342 // version >= 2
343
344 size_t gnu_nbucket_;
345 uint32_t* gnu_bucket_;
346 uint32_t* gnu_chain_;
347 uint32_t gnu_maskwords_;
348 uint32_t gnu_shift2_;
349 ElfW(Addr)* gnu_bloom_filter_;
350
351 soinfo* local_group_root_;
352
353 uint8_t* android_relocs_;
354 size_t android_relocs_size_;
355
356 const char* soname_;
357 std::string realpath_;
358
359 const ElfW(Versym)* versym_;
360
361 ElfW(Addr) verdef_ptr_;
362 size_t verdef_cnt_;
363
364 ElfW(Addr) verneed_ptr_;
365 size_t verneed_cnt_;
366
367 int target_sdk_version_;
368
369 // version >= 3
370 std::vector<std::string> dt_runpath_;
371 android_namespace_t* primary_namespace_;
372 android_namespace_list_t secondary_namespaces_;
373 uintptr_t handle_;
374
375 friend soinfo* get_libdl_info(const char* linker_path, const soinfo& linker_si);
376
377 // version >= 4
378 ElfW(Relr)* relr_;
379 size_t relr_count_;
380
381 // version >= 5
382 std::unique_ptr<soinfo_tls> tls_;
383 std::vector<TlsDynamicResolverArg> tlsdesc_args_;
384 };
385
386 // This function is used by dlvsym() to calculate hash of sym_ver
387 uint32_t calculate_elf_hash(const char* name);
388
389 const char* fix_dt_needed(const char* dt_needed, const char* sopath);
390
391 template<typename F>
for_each_dt_needed(const soinfo * si,F action)392 void for_each_dt_needed(const soinfo* si, F action) {
393 for (const ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) {
394 if (d->d_tag == DT_NEEDED) {
395 action(fix_dt_needed(si->get_string(d->d_un.d_val), si->get_realpath()));
396 }
397 }
398 }
399