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 <string>
34
35 #include "linker_namespaces.h"
36
37 #define FLAG_LINKED 0x00000001
38 #define FLAG_EXE 0x00000004 // The main executable
39 #define FLAG_LINKER 0x00000010 // The linker itself
40 #define FLAG_GNU_HASH 0x00000040 // uses gnu hash
41 #define FLAG_MAPPED_BY_CALLER 0x00000080 // the map is reserved by the caller
42 // and should not be unmapped
43 #define FLAG_IMAGE_LINKED 0x00000100 // Is image linked - this is a guard on link_image.
44 // The difference between this flag and
45 // FLAG_LINKED is that FLAG_LINKED
46 // means is set when load_group is
47 // successfully loaded whereas this
48 // flag is set to avoid linking image
49 // when link_image called for the
50 // second time. This situation happens
51 // when load group is crossing
52 // namespace boundary twice and second
53 // local group depends on the same libraries.
54 #define FLAG_TLS_NODELETE 0x00000200 // This flag set when there is at least one
55 // outstanding thread_local dtor
56 // registered with this soinfo. In such
57 // a case the actual unload is
58 // postponed until the last thread_local
59 // destructor associated with this
60 // soinfo is executed and this flag is
61 // unset.
62 #define FLAG_NEW_SOINFO 0x40000000 // new soinfo format
63
64 #define SOINFO_VERSION 4
65
66 typedef void (*linker_dtor_function_t)();
67 typedef void (*linker_ctor_function_t)(int, char**, char**);
68
69 class SymbolName {
70 public:
SymbolName(const char * name)71 explicit SymbolName(const char* name)
72 : name_(name), has_elf_hash_(false), has_gnu_hash_(false),
73 elf_hash_(0), gnu_hash_(0) { }
74
get_name()75 const char* get_name() {
76 return name_;
77 }
78
79 uint32_t elf_hash();
80 uint32_t gnu_hash();
81
82 private:
83 const char* name_;
84 bool has_elf_hash_;
85 bool has_gnu_hash_;
86 uint32_t elf_hash_;
87 uint32_t gnu_hash_;
88
89 DISALLOW_IMPLICIT_CONSTRUCTORS(SymbolName);
90 };
91
92 struct version_info {
version_infoversion_info93 constexpr version_info() : elf_hash(0), name(nullptr), target_si(nullptr) {}
94
95 uint32_t elf_hash;
96 const char* name;
97 const soinfo* target_si;
98 };
99
100 // TODO(dimitry): remove reference from soinfo member functions to this class.
101 class VersionTracker;
102
103 #if defined(__work_around_b_24465209__)
104 #define SOINFO_NAME_LEN 128
105 #endif
106
107 struct soinfo {
108 #if defined(__work_around_b_24465209__)
109 private:
110 char old_name_[SOINFO_NAME_LEN];
111 #endif
112 public:
113 const ElfW(Phdr)* phdr;
114 size_t phnum;
115 #if defined(__work_around_b_24465209__)
116 ElfW(Addr) unused0; // DO NOT USE, maintained for compatibility.
117 #endif
118 ElfW(Addr) base;
119 size_t size;
120
121 #if defined(__work_around_b_24465209__)
122 uint32_t unused1; // DO NOT USE, maintained for compatibility.
123 #endif
124
125 ElfW(Dyn)* dynamic;
126
127 #if defined(__work_around_b_24465209__)
128 uint32_t unused2; // DO NOT USE, maintained for compatibility
129 uint32_t unused3; // DO NOT USE, maintained for compatibility
130 #endif
131
132 soinfo* next;
133 private:
134 uint32_t flags_;
135
136 const char* strtab_;
137 ElfW(Sym)* symtab_;
138
139 size_t nbucket_;
140 size_t nchain_;
141 uint32_t* bucket_;
142 uint32_t* chain_;
143
144 #if defined(__mips__) || !defined(__LP64__)
145 // This is only used by mips and mips64, but needs to be here for
146 // all 32-bit architectures to preserve binary compatibility.
147 ElfW(Addr)** plt_got_;
148 #endif
149
150 #if defined(USE_RELA)
151 ElfW(Rela)* plt_rela_;
152 size_t plt_rela_count_;
153
154 ElfW(Rela)* rela_;
155 size_t rela_count_;
156 #else
157 ElfW(Rel)* plt_rel_;
158 size_t plt_rel_count_;
159
160 ElfW(Rel)* rel_;
161 size_t rel_count_;
162 #endif
163
164 linker_ctor_function_t* preinit_array_;
165 size_t preinit_array_count_;
166
167 linker_ctor_function_t* init_array_;
168 size_t init_array_count_;
169 linker_dtor_function_t* fini_array_;
170 size_t fini_array_count_;
171
172 linker_ctor_function_t init_func_;
173 linker_dtor_function_t fini_func_;
174
175 #if defined(__arm__)
176 public:
177 // ARM EABI section used for stack unwinding.
178 uint32_t* ARM_exidx;
179 size_t ARM_exidx_count;
180 private:
181 #elif defined(__mips__)
182 uint32_t mips_symtabno_;
183 uint32_t mips_local_gotno_;
184 uint32_t mips_gotsym_;
185 bool mips_relocate_got(const VersionTracker& version_tracker,
186 const soinfo_list_t& global_group,
187 const soinfo_list_t& local_group);
188 #if !defined(__LP64__)
189 bool mips_check_and_adjust_fp_modes();
190 #endif
191 #endif
192 size_t ref_count_;
193 public:
194 link_map link_map_head;
195
196 bool constructors_called;
197
198 // When you read a virtual address from the ELF file, add this
199 // value to get the corresponding address in the process' address space.
200 ElfW(Addr) load_bias;
201
202 #if !defined(__LP64__)
203 bool has_text_relocations;
204 #endif
205 bool has_DT_SYMBOLIC;
206
207 public:
208 soinfo(android_namespace_t* ns, const char* name, const struct stat* file_stat,
209 off64_t file_offset, int rtld_flags);
210 ~soinfo();
211
212 void call_constructors();
213 void call_destructors();
214 void call_pre_init_constructors();
215 bool prelink_image();
216 bool link_image(const soinfo_list_t& global_group, const soinfo_list_t& local_group,
217 const android_dlextinfo* extinfo);
218 bool protect_relro();
219
220 void add_child(soinfo* child);
221 void remove_all_links();
222
223 ino_t get_st_ino() const;
224 dev_t get_st_dev() const;
225 off64_t get_file_offset() const;
226
227 uint32_t get_rtld_flags() const;
228 uint32_t get_dt_flags_1() const;
229 void set_dt_flags_1(uint32_t dt_flags_1);
230
231 soinfo_list_t& get_children();
232 const soinfo_list_t& get_children() const;
233
234 soinfo_list_t& get_parents();
235
236 bool find_symbol_by_name(SymbolName& symbol_name,
237 const version_info* vi,
238 const ElfW(Sym)** symbol) const;
239
240 ElfW(Sym)* find_symbol_by_address(const void* addr);
241 ElfW(Addr) resolve_symbol_address(const ElfW(Sym)* s) const;
242
243 const char* get_string(ElfW(Word) index) const;
244 bool can_unload() const;
245 bool is_gnu_hash() const;
246
has_min_versionsoinfo247 bool inline has_min_version(uint32_t min_version __unused) const {
248 #if defined(__work_around_b_24465209__)
249 return (flags_ & FLAG_NEW_SOINFO) != 0 && version_ >= min_version;
250 #else
251 return true;
252 #endif
253 }
254
255 bool is_linked() const;
256 bool is_linker() const;
257 bool is_main_executable() const;
258
259 void set_linked();
260 void set_linker_flag();
261 void set_main_executable();
262 void set_nodelete();
263 void set_tls_nodelete();
264 void unset_tls_nodelete();
265
266 size_t increment_ref_count();
267 size_t decrement_ref_count();
268 size_t get_ref_count() const;
269
270 soinfo* get_local_group_root() const;
271
272 void set_soname(const char* soname);
273 const char* get_soname() const;
274 const char* get_realpath() const;
275 const ElfW(Versym)* get_versym(size_t n) const;
276 ElfW(Addr) get_verneed_ptr() const;
277 size_t get_verneed_cnt() const;
278 ElfW(Addr) get_verdef_ptr() const;
279 size_t get_verdef_cnt() const;
280
281 uint32_t get_target_sdk_version() const;
282
283 void set_dt_runpath(const char *);
284 const std::vector<std::string>& get_dt_runpath() const;
285 android_namespace_t* get_primary_namespace();
286 void add_secondary_namespace(android_namespace_t* secondary_ns);
287 android_namespace_list_t& get_secondary_namespaces();
288
289 void set_mapped_by_caller(bool reserved_map);
290 bool is_mapped_by_caller() const;
291
292 uintptr_t get_handle() const;
293 void generate_handle();
294 void* to_handle();
295
296 private:
297 bool is_image_linked() const;
298 void set_image_linked();
299
300 bool elf_lookup(SymbolName& symbol_name, const version_info* vi, uint32_t* symbol_index) const;
301 ElfW(Sym)* elf_addr_lookup(const void* addr);
302 bool gnu_lookup(SymbolName& symbol_name, const version_info* vi, uint32_t* symbol_index) const;
303 ElfW(Sym)* gnu_addr_lookup(const void* addr);
304
305 bool lookup_version_info(const VersionTracker& version_tracker, ElfW(Word) sym,
306 const char* sym_name, const version_info** vi);
307
308 template<typename ElfRelIteratorT>
309 bool relocate(const VersionTracker& version_tracker, ElfRelIteratorT&& rel_iterator,
310 const soinfo_list_t& global_group, const soinfo_list_t& local_group);
311 bool relocate_relr();
312 void apply_relr_reloc(ElfW(Addr) offset);
313
314 private:
315 // This part of the structure is only available
316 // when FLAG_NEW_SOINFO is set in this->flags.
317 uint32_t version_;
318
319 // version >= 0
320 dev_t st_dev_;
321 ino_t st_ino_;
322
323 // dependency graph
324 soinfo_list_t children_;
325 soinfo_list_t parents_;
326
327 // version >= 1
328 off64_t file_offset_;
329 uint32_t rtld_flags_;
330 uint32_t dt_flags_1_;
331 size_t strtab_size_;
332
333 // version >= 2
334
335 size_t gnu_nbucket_;
336 uint32_t* gnu_bucket_;
337 uint32_t* gnu_chain_;
338 uint32_t gnu_maskwords_;
339 uint32_t gnu_shift2_;
340 ElfW(Addr)* gnu_bloom_filter_;
341
342 soinfo* local_group_root_;
343
344 uint8_t* android_relocs_;
345 size_t android_relocs_size_;
346
347 const char* soname_;
348 std::string realpath_;
349
350 const ElfW(Versym)* versym_;
351
352 ElfW(Addr) verdef_ptr_;
353 size_t verdef_cnt_;
354
355 ElfW(Addr) verneed_ptr_;
356 size_t verneed_cnt_;
357
358 uint32_t target_sdk_version_;
359
360 // version >= 3
361 std::vector<std::string> dt_runpath_;
362 android_namespace_t* primary_namespace_;
363 android_namespace_list_t secondary_namespaces_;
364 uintptr_t handle_;
365
366 friend soinfo* get_libdl_info(const char* linker_path,
367 const soinfo& linker_si,
368 const link_map& linker_map);
369
370 // version >= 4
371 ElfW(Relr)* relr_;
372 size_t relr_count_;
373 };
374
375 // This function is used by dlvsym() to calculate hash of sym_ver
376 uint32_t calculate_elf_hash(const char* name);
377
378 const char* fix_dt_needed(const char* dt_needed, const char* sopath);
379
380 template<typename F>
for_each_dt_needed(const soinfo * si,F action)381 void for_each_dt_needed(const soinfo* si, F action) {
382 for (const ElfW(Dyn)* d = si->dynamic; d->d_tag != DT_NULL; ++d) {
383 if (d->d_tag == DT_NEEDED) {
384 action(fix_dt_needed(si->get_string(d->d_un.d_val), si->get_realpath()));
385 }
386 }
387 }
388