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 "async_safe/CHECK.h"
38 #include "linker_namespaces.h"
39 #include "linker_tls.h"
40 #include "private/bionic_elf_tls.h"
41 #include "private/bionic_globals.h"
42
43 #define FLAG_LINKED 0x00000001
44 #define FLAG_EXE 0x00000004 // The main executable
45 #define FLAG_LINKER 0x00000010 // The linker itself
46 #define FLAG_GNU_HASH 0x00000040 // uses gnu hash
47 #define FLAG_MAPPED_BY_CALLER 0x00000080 // the map is reserved by the caller
48 // and should not be unmapped
49 #define FLAG_IMAGE_LINKED 0x00000100 // Is image linked - this is a guard on link_image.
50 // The difference between this flag and
51 // FLAG_LINKED is that FLAG_LINKED
52 // means is set when load_group is
53 // successfully loaded whereas this
54 // flag is set to avoid linking image
55 // when link_image called for the
56 // second time. This situation happens
57 // when load group is crossing
58 // namespace boundary twice and second
59 // local group depends on the same libraries.
60 #define FLAG_RESERVED 0x00000200 // This flag was set when there is at least one
61 // outstanding thread_local dtor
62 // registered with this soinfo. In such
63 // a case the actual unload is
64 // postponed until the last thread_local
65 // destructor associated with this
66 // soinfo is executed and this flag is
67 // unset.
68 #define FLAG_PRELINKED 0x00000400 // prelink_image has successfully processed this soinfo
69 #define FLAG_NEW_SOINFO 0x40000000 // new soinfo format
70
71 #define SOINFO_VERSION 6
72
73 ElfW(Addr) call_ifunc_resolver(ElfW(Addr) resolver_addr);
74
75 typedef void (*linker_dtor_function_t)();
76 typedef void (*linker_ctor_function_t)(int, char**, char**);
77
78 // An entry within a SymbolLookupList.
79 struct SymbolLookupLib {
80 uint32_t gnu_maskwords_ = 0;
81 uint32_t gnu_shift2_ = 0;
82 ElfW(Addr)* gnu_bloom_filter_ = nullptr;
83
84 const char* strtab_;
85 size_t strtab_size_;
86 const ElfW(Sym)* symtab_;
87 const ElfW(Versym)* versym_;
88
89 const uint32_t* gnu_chain_;
90 size_t gnu_nbucket_;
91 uint32_t* gnu_bucket_;
92
93 soinfo* si_ = nullptr;
94
needs_sysv_lookupSymbolLookupLib95 bool needs_sysv_lookup() const { return si_ != nullptr && gnu_bloom_filter_ == nullptr; }
96 };
97
98 // A list of libraries to search for a symbol.
99 class SymbolLookupList {
100 std::vector<SymbolLookupLib> libs_;
101 SymbolLookupLib sole_lib_;
102 const SymbolLookupLib* begin_;
103 const SymbolLookupLib* end_;
104 size_t slow_path_count_ = 0;
105
106 public:
107 explicit SymbolLookupList(soinfo* si);
108 SymbolLookupList(const soinfo_list_t& global_group, const soinfo_list_t& local_group);
109 void set_dt_symbolic_lib(soinfo* symbolic_lib);
110
begin()111 const SymbolLookupLib* begin() const { return begin_; }
end()112 const SymbolLookupLib* end() const { return end_; }
needs_slow_path()113 bool needs_slow_path() const { return slow_path_count_ > 0; }
114 };
115
116 class SymbolName {
117 public:
SymbolName(const char * name)118 explicit SymbolName(const char* name)
119 : name_(name), has_elf_hash_(false), has_gnu_hash_(false),
120 elf_hash_(0), gnu_hash_(0) { }
121
get_name()122 const char* get_name() {
123 return name_;
124 }
125
126 uint32_t elf_hash();
127 uint32_t gnu_hash();
128
129 private:
130 const char* name_;
131 bool has_elf_hash_;
132 bool has_gnu_hash_;
133 uint32_t elf_hash_;
134 uint32_t gnu_hash_;
135
136 DISALLOW_IMPLICIT_CONSTRUCTORS(SymbolName);
137 };
138
139 struct version_info {
version_infoversion_info140 constexpr version_info() : elf_hash(0), name(nullptr), target_si(nullptr) {}
141
142 uint32_t elf_hash;
143 const char* name;
144 const soinfo* target_si;
145 };
146
147 // TODO(dimitry): remove reference from soinfo member functions to this class.
148 class VersionTracker;
149
150 struct soinfo_tls {
151 TlsSegment segment;
152 size_t module_id = kTlsUninitializedModuleId;
153 };
154
155 #if defined(__work_around_b_24465209__)
156 #define SOINFO_NAME_LEN 128
157 #endif
158
159 struct soinfo {
160 #if defined(__work_around_b_24465209__)
161 private:
162 char old_name_[SOINFO_NAME_LEN];
163 #endif
164 public:
165 const ElfW(Phdr)* phdr;
166 size_t phnum;
167 #if defined(__work_around_b_24465209__)
168 ElfW(Addr) unused0; // DO NOT USE, maintained for compatibility.
169 #endif
170 ElfW(Addr) base;
171 size_t size;
172
173 #if defined(__work_around_b_24465209__)
174 uint32_t unused1; // DO NOT USE, maintained for compatibility.
175 #endif
176
177 ElfW(Dyn)* dynamic;
178
179 #if defined(__work_around_b_24465209__)
180 uint32_t unused2; // DO NOT USE, maintained for compatibility
181 uint32_t unused3; // DO NOT USE, maintained for compatibility
182 #endif
183
184 soinfo* next;
185 private:
186 uint32_t flags_;
187
188 const char* strtab_;
189 ElfW(Sym)* symtab_;
190
191 size_t nbucket_;
192 size_t nchain_;
193 uint32_t* bucket_;
194 uint32_t* chain_;
195
196 #if !defined(__LP64__)
197 ElfW(Addr)** unused4; // DO NOT USE, maintained for compatibility
198 #endif
199
200 #if defined(USE_RELA)
201 ElfW(Rela)* plt_rela_;
202 size_t plt_rela_count_;
203
204 ElfW(Rela)* rela_;
205 size_t rela_count_;
206 #else
207 ElfW(Rel)* plt_rel_;
208 size_t plt_rel_count_;
209
210 ElfW(Rel)* rel_;
211 size_t rel_count_;
212 #endif
213
214 linker_ctor_function_t* preinit_array_;
215 size_t preinit_array_count_;
216
217 linker_ctor_function_t* init_array_;
218 size_t init_array_count_;
219 linker_dtor_function_t* fini_array_;
220 size_t fini_array_count_;
221
222 linker_ctor_function_t init_func_;
223 linker_dtor_function_t fini_func_;
224
225 #if defined(__arm__)
226 public:
227 // ARM EABI section used for stack unwinding.
228 uint32_t* ARM_exidx;
229 size_t ARM_exidx_count;
230 private:
231 #endif
232 size_t ref_count_;
233 public:
234 link_map link_map_head;
235
236 bool constructors_called;
237
238 // When you read a virtual address from the ELF file, add this
239 // value to get the corresponding address in the process' address space.
240 ElfW(Addr) load_bias;
241
242 #if !defined(__LP64__)
243 bool has_text_relocations;
244 #endif
245 bool has_DT_SYMBOLIC;
246
247 public:
248 soinfo(android_namespace_t* ns, const char* name, const struct stat* file_stat,
249 off64_t file_offset, int rtld_flags);
250 ~soinfo();
251
252 void call_constructors();
253 void call_destructors();
254 void call_pre_init_constructors();
255 bool prelink_image();
256 bool link_image(const SymbolLookupList& lookup_list, soinfo* local_group_root,
257 const android_dlextinfo* extinfo, size_t* relro_fd_offset);
258 bool protect_relro();
259
260 void add_child(soinfo* child);
261 void remove_all_links();
262
263 ino_t get_st_ino() const;
264 dev_t get_st_dev() const;
265 off64_t get_file_offset() const;
266
267 uint32_t get_rtld_flags() const;
268 uint32_t get_dt_flags_1() const;
269 void set_dt_flags_1(uint32_t dt_flags_1);
270
271 soinfo_list_t& get_children();
272 const soinfo_list_t& get_children() const;
273
274 soinfo_list_t& get_parents();
275
276 const ElfW(Sym)* find_symbol_by_name(SymbolName& symbol_name, const version_info* vi) const;
277
278 ElfW(Sym)* find_symbol_by_address(const void* addr);
279
resolve_symbol_addresssoinfo280 ElfW(Addr) resolve_symbol_address(const ElfW(Sym)* s) const {
281 if (ELF_ST_TYPE(s->st_info) == STT_GNU_IFUNC) {
282 return call_ifunc_resolver(s->st_value + load_bias);
283 }
284
285 return static_cast<ElfW(Addr)>(s->st_value + load_bias);
286 }
287
288 const char* get_string(ElfW(Word) index) const;
289 bool can_unload() const;
290 bool is_gnu_hash() const;
291
has_min_versionsoinfo292 bool inline has_min_version(uint32_t min_version __unused) const {
293 #if defined(__work_around_b_24465209__)
294 return (flags_ & FLAG_NEW_SOINFO) != 0 && version_ >= min_version;
295 #else
296 return true;
297 #endif
298 }
299
ElfWsoinfo300 const ElfW(Versym)* get_versym_table() const {
301 return has_min_version(2) ? versym_ : nullptr;
302 }
303
304 bool is_linked() const;
305 bool is_linker() const;
306 bool is_main_executable() const;
307
308 void set_linked();
309 void set_linker_flag();
310 void set_main_executable();
311 void set_nodelete();
312
313 size_t increment_ref_count();
314 size_t decrement_ref_count();
315 size_t get_ref_count() const;
316
317 soinfo* get_local_group_root() const;
318
319 void set_soname(const char* soname);
320 const char* get_soname() const;
321 void set_realpath(const char* path);
322 const char* get_realpath() const;
323 const ElfW(Versym)* get_versym(size_t n) const;
324 ElfW(Addr) get_verneed_ptr() const;
325 size_t get_verneed_cnt() const;
326 ElfW(Addr) get_verdef_ptr() const;
327 size_t get_verdef_cnt() const;
328
329 int get_target_sdk_version() const;
330
331 void set_dt_runpath(const char *);
332 const std::vector<std::string>& get_dt_runpath() const;
333 android_namespace_t* get_primary_namespace();
334 void add_secondary_namespace(android_namespace_t* secondary_ns);
335 android_namespace_list_t& get_secondary_namespaces();
336
get_tlssoinfo337 soinfo_tls* get_tls() const {
338 return has_min_version(5) ? tls_.get() : nullptr;
339 }
340
341 void set_mapped_by_caller(bool reserved_map);
342 bool is_mapped_by_caller() const;
343
344 uintptr_t get_handle() const;
345 void generate_handle();
346 void* to_handle();
347
348 SymbolLookupLib get_lookup_lib();
349
350 void set_gap_start(ElfW(Addr) gap_start);
351 ElfW(Addr) get_gap_start() const;
352
353 void set_gap_size(size_t gap_size);
354 size_t get_gap_size() const;
355
memtag_dynamic_entriessoinfo356 const memtag_dynamic_entries_t* memtag_dynamic_entries() const {
357 CHECK(has_min_version(7));
358 return &memtag_dynamic_entries_;
359 }
memtag_globalssoinfo360 void* memtag_globals() const { return memtag_dynamic_entries()->memtag_globals; }
memtag_globalsszsoinfo361 size_t memtag_globalssz() const { return memtag_dynamic_entries()->memtag_globalssz; }
has_memtag_modesoinfo362 bool has_memtag_mode() const { return memtag_dynamic_entries()->has_memtag_mode; }
memtag_modesoinfo363 unsigned memtag_mode() const { return memtag_dynamic_entries()->memtag_mode; }
memtag_heapsoinfo364 bool memtag_heap() const { return memtag_dynamic_entries()->memtag_heap; }
memtag_stacksoinfo365 bool memtag_stack() const { return memtag_dynamic_entries()->memtag_stack; }
366
set_should_pad_segmentssoinfo367 void set_should_pad_segments(bool should_pad_segments) {
368 should_pad_segments_ = should_pad_segments;
369 }
should_pad_segmentssoinfo370 bool should_pad_segments() const { return should_pad_segments_; }
371
372 private:
373 bool is_image_linked() const;
374 void set_image_linked();
375
376 const ElfW(Sym)* gnu_lookup(SymbolName& symbol_name, const version_info* vi) const;
377 const ElfW(Sym)* elf_lookup(SymbolName& symbol_name, const version_info* vi) const;
378 ElfW(Sym)* gnu_addr_lookup(const void* addr);
379 ElfW(Sym)* elf_addr_lookup(const void* addr);
380
381 public:
382 bool lookup_version_info(const VersionTracker& version_tracker, ElfW(Word) sym,
383 const char* sym_name, const version_info** vi);
384
385 private:
386 bool relocate(const SymbolLookupList& lookup_list);
387
388 // This part of the structure is only available
389 // when FLAG_NEW_SOINFO is set in this->flags.
390 uint32_t version_;
391
392 // version >= 0
393 dev_t st_dev_;
394 ino_t st_ino_;
395
396 // dependency graph
397 soinfo_list_t children_;
398 soinfo_list_t parents_;
399
400 // version >= 1
401 off64_t file_offset_;
402 uint32_t rtld_flags_;
403 uint32_t dt_flags_1_;
404 size_t strtab_size_;
405
406 // version >= 2
407
408 size_t gnu_nbucket_;
409 uint32_t* gnu_bucket_;
410 uint32_t* gnu_chain_;
411 uint32_t gnu_maskwords_;
412 uint32_t gnu_shift2_;
413 ElfW(Addr)* gnu_bloom_filter_;
414
415 soinfo* local_group_root_;
416
417 uint8_t* android_relocs_;
418 size_t android_relocs_size_;
419
420 std::string soname_;
421 std::string realpath_;
422
423 const ElfW(Versym)* versym_;
424
425 ElfW(Addr) verdef_ptr_;
426 size_t verdef_cnt_;
427
428 ElfW(Addr) verneed_ptr_;
429 size_t verneed_cnt_;
430
431 int target_sdk_version_;
432
433 // version >= 3
434 std::vector<std::string> dt_runpath_;
435 android_namespace_t* primary_namespace_;
436 android_namespace_list_t secondary_namespaces_;
437 uintptr_t handle_;
438
439 friend soinfo* get_libdl_info(const soinfo& linker_si);
440
441 // version >= 4
442 ElfW(Relr)* relr_;
443 size_t relr_count_;
444
445 // version >= 5
446 std::unique_ptr<soinfo_tls> tls_;
447 std::vector<TlsDynamicResolverArg> tlsdesc_args_;
448
449 // version >= 6
450 ElfW(Addr) gap_start_;
451 size_t gap_size_;
452
453 // version >= 7
454 memtag_dynamic_entries_t memtag_dynamic_entries_;
455
456 // Pad gaps between segments when memory mapping?
457 bool should_pad_segments_ = false;
458 };
459
460 // This function is used by dlvsym() to calculate hash of sym_ver
461 uint32_t calculate_elf_hash(const char* name);
462
463 const char* fix_dt_needed(const char* dt_needed, const char* sopath);
464
465 template<typename F>
for_each_dt_needed(const soinfo * si,F action)466 void for_each_dt_needed(const soinfo* si, F action) {
467 for (const ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) {
468 if (d->d_tag == DT_NEEDED) {
469 action(fix_dt_needed(si->get_string(d->d_un.d_val), si->get_realpath()));
470 }
471 }
472 }
473
474 const ElfW(Sym)* soinfo_do_lookup(const char* name, const version_info* vi,
475 soinfo** si_found_in, const SymbolLookupList& lookup_list);
476