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_PRELINKED 0x00000400 // prelink_image has successfully processed this soinfo
67 #define FLAG_NEW_SOINFO 0x40000000 // new soinfo format
68
69 #define SOINFO_VERSION 6
70
71 ElfW(Addr) call_ifunc_resolver(ElfW(Addr) resolver_addr);
72
73 typedef void (*linker_dtor_function_t)();
74 typedef void (*linker_ctor_function_t)(int, char**, char**);
75
76 // An entry within a SymbolLookupList.
77 struct SymbolLookupLib {
78 uint32_t gnu_maskwords_ = 0;
79 uint32_t gnu_shift2_ = 0;
80 ElfW(Addr)* gnu_bloom_filter_ = nullptr;
81
82 const char* strtab_;
83 size_t strtab_size_;
84 const ElfW(Sym)* symtab_;
85 const ElfW(Versym)* versym_;
86
87 const uint32_t* gnu_chain_;
88 size_t gnu_nbucket_;
89 uint32_t* gnu_bucket_;
90
91 soinfo* si_ = nullptr;
92
needs_sysv_lookupSymbolLookupLib93 bool needs_sysv_lookup() const { return si_ != nullptr && gnu_bloom_filter_ == nullptr; }
94 };
95
96 // A list of libraries to search for a symbol.
97 class SymbolLookupList {
98 std::vector<SymbolLookupLib> libs_;
99 SymbolLookupLib sole_lib_;
100 const SymbolLookupLib* begin_;
101 const SymbolLookupLib* end_;
102 size_t slow_path_count_ = 0;
103
104 public:
105 explicit SymbolLookupList(soinfo* si);
106 SymbolLookupList(const soinfo_list_t& global_group, const soinfo_list_t& local_group);
107 void set_dt_symbolic_lib(soinfo* symbolic_lib);
108
begin()109 const SymbolLookupLib* begin() const { return begin_; }
end()110 const SymbolLookupLib* end() const { return end_; }
needs_slow_path()111 bool needs_slow_path() const { return slow_path_count_ > 0; }
112 };
113
114 class SymbolName {
115 public:
SymbolName(const char * name)116 explicit SymbolName(const char* name)
117 : name_(name), has_elf_hash_(false), has_gnu_hash_(false),
118 elf_hash_(0), gnu_hash_(0) { }
119
get_name()120 const char* get_name() {
121 return name_;
122 }
123
124 uint32_t elf_hash();
125 uint32_t gnu_hash();
126
127 private:
128 const char* name_;
129 bool has_elf_hash_;
130 bool has_gnu_hash_;
131 uint32_t elf_hash_;
132 uint32_t gnu_hash_;
133
134 DISALLOW_IMPLICIT_CONSTRUCTORS(SymbolName);
135 };
136
137 struct version_info {
version_infoversion_info138 constexpr version_info() : elf_hash(0), name(nullptr), target_si(nullptr) {}
139
140 uint32_t elf_hash;
141 const char* name;
142 const soinfo* target_si;
143 };
144
145 // TODO(dimitry): remove reference from soinfo member functions to this class.
146 class VersionTracker;
147
148 struct soinfo_tls {
149 TlsSegment segment;
150 size_t module_id = kTlsUninitializedModuleId;
151 };
152
153 #if defined(__work_around_b_24465209__)
154 #define SOINFO_NAME_LEN 128
155 #endif
156
157 struct soinfo {
158 #if defined(__work_around_b_24465209__)
159 private:
160 char old_name_[SOINFO_NAME_LEN];
161 #endif
162 public:
163 const ElfW(Phdr)* phdr;
164 size_t phnum;
165 #if defined(__work_around_b_24465209__)
166 ElfW(Addr) unused0; // DO NOT USE, maintained for compatibility.
167 #endif
168 ElfW(Addr) base;
169 size_t size;
170
171 #if defined(__work_around_b_24465209__)
172 uint32_t unused1; // DO NOT USE, maintained for compatibility.
173 #endif
174
175 ElfW(Dyn)* dynamic;
176
177 #if defined(__work_around_b_24465209__)
178 uint32_t unused2; // DO NOT USE, maintained for compatibility
179 uint32_t unused3; // DO NOT USE, maintained for compatibility
180 #endif
181
182 soinfo* next;
183 private:
184 uint32_t flags_;
185
186 const char* strtab_;
187 ElfW(Sym)* symtab_;
188
189 size_t nbucket_;
190 size_t nchain_;
191 uint32_t* bucket_;
192 uint32_t* chain_;
193
194 #if !defined(__LP64__)
195 ElfW(Addr)** unused4; // DO NOT USE, maintained for compatibility
196 #endif
197
198 #if defined(USE_RELA)
199 ElfW(Rela)* plt_rela_;
200 size_t plt_rela_count_;
201
202 ElfW(Rela)* rela_;
203 size_t rela_count_;
204 #else
205 ElfW(Rel)* plt_rel_;
206 size_t plt_rel_count_;
207
208 ElfW(Rel)* rel_;
209 size_t rel_count_;
210 #endif
211
212 linker_ctor_function_t* preinit_array_;
213 size_t preinit_array_count_;
214
215 linker_ctor_function_t* init_array_;
216 size_t init_array_count_;
217 linker_dtor_function_t* fini_array_;
218 size_t fini_array_count_;
219
220 linker_ctor_function_t init_func_;
221 linker_dtor_function_t fini_func_;
222
223 #if defined(__arm__)
224 public:
225 // ARM EABI section used for stack unwinding.
226 uint32_t* ARM_exidx;
227 size_t ARM_exidx_count;
228 private:
229 #endif
230 size_t ref_count_;
231 public:
232 link_map link_map_head;
233
234 bool constructors_called;
235
236 // When you read a virtual address from the ELF file, add this
237 // value to get the corresponding address in the process' address space.
238 ElfW(Addr) load_bias;
239
240 #if !defined(__LP64__)
241 bool has_text_relocations;
242 #endif
243 bool has_DT_SYMBOLIC;
244
245 public:
246 soinfo(android_namespace_t* ns, const char* name, const struct stat* file_stat,
247 off64_t file_offset, int rtld_flags);
248 ~soinfo();
249
250 void call_constructors();
251 void call_destructors();
252 void call_pre_init_constructors();
253 bool prelink_image();
254 bool link_image(const SymbolLookupList& lookup_list, soinfo* local_group_root,
255 const android_dlextinfo* extinfo, size_t* relro_fd_offset);
256 bool protect_relro();
257
258 void add_child(soinfo* child);
259 void remove_all_links();
260
261 ino_t get_st_ino() const;
262 dev_t get_st_dev() const;
263 off64_t get_file_offset() const;
264
265 uint32_t get_rtld_flags() const;
266 uint32_t get_dt_flags_1() const;
267 void set_dt_flags_1(uint32_t dt_flags_1);
268
269 soinfo_list_t& get_children();
270 const soinfo_list_t& get_children() const;
271
272 soinfo_list_t& get_parents();
273
274 const ElfW(Sym)* find_symbol_by_name(SymbolName& symbol_name, const version_info* vi) const;
275
276 ElfW(Sym)* find_symbol_by_address(const void* addr);
277
resolve_symbol_addresssoinfo278 ElfW(Addr) resolve_symbol_address(const ElfW(Sym)* s) const {
279 if (ELF_ST_TYPE(s->st_info) == STT_GNU_IFUNC) {
280 return call_ifunc_resolver(s->st_value + load_bias);
281 }
282
283 return static_cast<ElfW(Addr)>(s->st_value + load_bias);
284 }
285
286 const char* get_string(ElfW(Word) index) const;
287 bool can_unload() const;
288 bool is_gnu_hash() const;
289
has_min_versionsoinfo290 bool inline has_min_version(uint32_t min_version __unused) const {
291 #if defined(__work_around_b_24465209__)
292 return (flags_ & FLAG_NEW_SOINFO) != 0 && version_ >= min_version;
293 #else
294 return true;
295 #endif
296 }
297
ElfWsoinfo298 const ElfW(Versym)* get_versym_table() const {
299 return has_min_version(2) ? versym_ : nullptr;
300 }
301
302 bool is_linked() const;
303 bool is_linker() const;
304 bool is_main_executable() const;
305
306 void set_linked();
307 void set_linker_flag();
308 void set_main_executable();
309 void set_nodelete();
310
311 size_t increment_ref_count();
312 size_t decrement_ref_count();
313 size_t get_ref_count() const;
314
315 soinfo* get_local_group_root() const;
316
317 void set_soname(const char* soname);
318 const char* get_soname() const;
319 void set_realpath(const char* path);
320 const char* get_realpath() const;
321 const ElfW(Versym)* get_versym(size_t n) const;
322 ElfW(Addr) get_verneed_ptr() const;
323 size_t get_verneed_cnt() const;
324 ElfW(Addr) get_verdef_ptr() const;
325 size_t get_verdef_cnt() const;
326
327 int get_target_sdk_version() const;
328
329 void set_dt_runpath(const char *);
330 const std::vector<std::string>& get_dt_runpath() const;
331 android_namespace_t* get_primary_namespace();
332 void add_secondary_namespace(android_namespace_t* secondary_ns);
333 android_namespace_list_t& get_secondary_namespaces();
334
get_tlssoinfo335 soinfo_tls* get_tls() const {
336 return has_min_version(5) ? tls_.get() : nullptr;
337 }
338
339 void set_mapped_by_caller(bool reserved_map);
340 bool is_mapped_by_caller() const;
341
342 uintptr_t get_handle() const;
343 void generate_handle();
344 void* to_handle();
345
346 SymbolLookupLib get_lookup_lib();
347
348 void set_gap_start(ElfW(Addr) gap_start);
349 ElfW(Addr) get_gap_start() const;
350
351 void set_gap_size(size_t gap_size);
352 size_t get_gap_size() const;
353
354 private:
355 bool is_image_linked() const;
356 void set_image_linked();
357
358 const ElfW(Sym)* gnu_lookup(SymbolName& symbol_name, const version_info* vi) const;
359 const ElfW(Sym)* elf_lookup(SymbolName& symbol_name, const version_info* vi) const;
360 ElfW(Sym)* gnu_addr_lookup(const void* addr);
361 ElfW(Sym)* elf_addr_lookup(const void* addr);
362
363 public:
364 bool lookup_version_info(const VersionTracker& version_tracker, ElfW(Word) sym,
365 const char* sym_name, const version_info** vi);
366
367 private:
368 bool relocate(const SymbolLookupList& lookup_list);
369 bool relocate_relr();
370 void apply_relr_reloc(ElfW(Addr) offset);
371
372 // This part of the structure is only available
373 // when FLAG_NEW_SOINFO is set in this->flags.
374 uint32_t version_;
375
376 // version >= 0
377 dev_t st_dev_;
378 ino_t st_ino_;
379
380 // dependency graph
381 soinfo_list_t children_;
382 soinfo_list_t parents_;
383
384 // version >= 1
385 off64_t file_offset_;
386 uint32_t rtld_flags_;
387 uint32_t dt_flags_1_;
388 size_t strtab_size_;
389
390 // version >= 2
391
392 size_t gnu_nbucket_;
393 uint32_t* gnu_bucket_;
394 uint32_t* gnu_chain_;
395 uint32_t gnu_maskwords_;
396 uint32_t gnu_shift2_;
397 ElfW(Addr)* gnu_bloom_filter_;
398
399 soinfo* local_group_root_;
400
401 uint8_t* android_relocs_;
402 size_t android_relocs_size_;
403
404 std::string soname_;
405 std::string realpath_;
406
407 const ElfW(Versym)* versym_;
408
409 ElfW(Addr) verdef_ptr_;
410 size_t verdef_cnt_;
411
412 ElfW(Addr) verneed_ptr_;
413 size_t verneed_cnt_;
414
415 int target_sdk_version_;
416
417 // version >= 3
418 std::vector<std::string> dt_runpath_;
419 android_namespace_t* primary_namespace_;
420 android_namespace_list_t secondary_namespaces_;
421 uintptr_t handle_;
422
423 friend soinfo* get_libdl_info(const soinfo& linker_si);
424
425 // version >= 4
426 ElfW(Relr)* relr_;
427 size_t relr_count_;
428
429 // version >= 5
430 std::unique_ptr<soinfo_tls> tls_;
431 std::vector<TlsDynamicResolverArg> tlsdesc_args_;
432
433 // version >= 6
434 ElfW(Addr) gap_start_;
435 size_t gap_size_;
436 };
437
438 // This function is used by dlvsym() to calculate hash of sym_ver
439 uint32_t calculate_elf_hash(const char* name);
440
441 const char* fix_dt_needed(const char* dt_needed, const char* sopath);
442
443 template<typename F>
for_each_dt_needed(const soinfo * si,F action)444 void for_each_dt_needed(const soinfo* si, F action) {
445 for (const ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) {
446 if (d->d_tag == DT_NEEDED) {
447 action(fix_dt_needed(si->get_string(d->d_un.d_val), si->get_realpath()));
448 }
449 }
450 }
451
452 const ElfW(Sym)* soinfo_do_lookup(const char* name, const version_info* vi,
453 soinfo** si_found_in, const SymbolLookupList& lookup_list);
454