1 | /* Data structure for communication from the run-time dynamic linker for |
2 | loaded ELF shared objects. |
3 | Copyright (C) 1995-2016 Free Software Foundation, Inc. |
4 | This file is part of the GNU C Library. |
5 | |
6 | The GNU C Library is free software; you can redistribute it and/or |
7 | modify it under the terms of the GNU Lesser General Public |
8 | License as published by the Free Software Foundation; either |
9 | version 2.1 of the License, or (at your option) any later version. |
10 | |
11 | The GNU C Library is distributed in the hope that it will be useful, |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
14 | Lesser General Public License for more details. |
15 | |
16 | You should have received a copy of the GNU Lesser General Public |
17 | License along with the GNU C Library; if not, see |
18 | <http://www.gnu.org/licenses/>. */ |
19 | |
20 | #ifndef _PRIVATE_LINK_H |
21 | #define _PRIVATE_LINK_H 1 |
22 | |
23 | #ifdef _LINK_H |
24 | # error this should be impossible |
25 | #endif |
26 | |
27 | /* Get most of the contents from the public header, but we define a |
28 | different `struct link_map' type for private use. The la_objopen |
29 | prototype uses the type, so we have to declare it separately. */ |
30 | #define link_map link_map_public |
31 | #define la_objopen la_objopen_wrongproto |
32 | #include <elf/link.h> |
33 | #undef link_map |
34 | #undef la_objopen |
35 | |
36 | struct link_map; |
37 | extern unsigned int la_objopen (struct link_map *__map, Lmid_t __lmid, |
38 | uintptr_t *__cookie); |
39 | |
40 | #include <stdint.h> |
41 | #include <stddef.h> |
42 | #include <linkmap.h> |
43 | #include <dl-fileid.h> |
44 | #include <dl-lookupcfg.h> |
45 | #include <tls.h> |
46 | #include <libc-lock.h> |
47 | |
48 | |
49 | /* Some internal data structures of the dynamic linker used in the |
50 | linker map. We only provide forward declarations. */ |
51 | struct libname_list; |
52 | struct r_found_version; |
53 | struct r_search_path_elem; |
54 | |
55 | /* Forward declaration. */ |
56 | struct link_map; |
57 | |
58 | /* Structure to describe a single list of scope elements. The lookup |
59 | functions get passed an array of pointers to such structures. */ |
60 | struct r_scope_elem |
61 | { |
62 | /* Array of maps for the scope. */ |
63 | struct link_map **r_list; |
64 | /* Number of entries in the scope. */ |
65 | unsigned int r_nlist; |
66 | }; |
67 | |
68 | |
69 | /* Structure to record search path and allocation mechanism. */ |
70 | struct r_search_path_struct |
71 | { |
72 | struct r_search_path_elem **dirs; |
73 | int malloced; |
74 | }; |
75 | |
76 | |
77 | /* Structure describing a loaded shared object. The `l_next' and `l_prev' |
78 | members form a chain of all the shared objects loaded at startup. |
79 | |
80 | These data structures exist in space used by the run-time dynamic linker; |
81 | modifying them may have disastrous results. |
82 | |
83 | This data structure might change in future, if necessary. User-level |
84 | programs must avoid defining objects of this type. */ |
85 | |
86 | struct link_map |
87 | { |
88 | /* These first few members are part of the protocol with the debugger. |
89 | This is the same format used in SVR4. */ |
90 | |
91 | ElfW(Addr) l_addr; /* Difference between the address in the ELF |
92 | file and the addresses in memory. */ |
93 | char *l_name; /* Absolute file name object was found in. */ |
94 | ElfW(Dyn) *l_ld; /* Dynamic section of the shared object. */ |
95 | struct link_map *l_next, *l_prev; /* Chain of loaded objects. */ |
96 | |
97 | /* All following members are internal to the dynamic linker. |
98 | They may change without notice. */ |
99 | |
100 | /* This is an element which is only ever different from a pointer to |
101 | the very same copy of this type for ld.so when it is used in more |
102 | than one namespace. */ |
103 | struct link_map *l_real; |
104 | |
105 | /* Number of the namespace this link map belongs to. */ |
106 | Lmid_t l_ns; |
107 | |
108 | struct libname_list *l_libname; |
109 | /* Indexed pointers to dynamic section. |
110 | [0,DT_NUM) are indexed by the processor-independent tags. |
111 | [DT_NUM,DT_NUM+DT_THISPROCNUM) are indexed by the tag minus DT_LOPROC. |
112 | [DT_NUM+DT_THISPROCNUM,DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM) are |
113 | indexed by DT_VERSIONTAGIDX(tagvalue). |
114 | [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM, |
115 | DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM) are indexed by |
116 | DT_EXTRATAGIDX(tagvalue). |
117 | [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM, |
118 | DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM) are |
119 | indexed by DT_VALTAGIDX(tagvalue) and |
120 | [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM, |
121 | DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM+DT_ADDRNUM) |
122 | are indexed by DT_ADDRTAGIDX(tagvalue), see <elf.h>. */ |
123 | |
124 | ElfW(Dyn) *l_info[DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM |
125 | + DT_EXTRANUM + DT_VALNUM + DT_ADDRNUM]; |
126 | const ElfW(Phdr) *l_phdr; /* Pointer to program header table in core. */ |
127 | ElfW(Addr) l_entry; /* Entry point location. */ |
128 | ElfW(Half) l_phnum; /* Number of program header entries. */ |
129 | ElfW(Half) l_ldnum; /* Number of dynamic segment entries. */ |
130 | |
131 | /* Array of DT_NEEDED dependencies and their dependencies, in |
132 | dependency order for symbol lookup (with and without |
133 | duplicates). There is no entry before the dependencies have |
134 | been loaded. */ |
135 | struct r_scope_elem l_searchlist; |
136 | |
137 | /* We need a special searchlist to process objects marked with |
138 | DT_SYMBOLIC. */ |
139 | struct r_scope_elem l_symbolic_searchlist; |
140 | |
141 | /* Dependent object that first caused this object to be loaded. */ |
142 | struct link_map *l_loader; |
143 | |
144 | /* Array with version names. */ |
145 | struct r_found_version *l_versions; |
146 | unsigned int l_nversions; |
147 | |
148 | /* Symbol hash table. */ |
149 | Elf_Symndx l_nbuckets; |
150 | Elf32_Word l_gnu_bitmask_idxbits; |
151 | Elf32_Word l_gnu_shift; |
152 | const ElfW(Addr) *l_gnu_bitmask; |
153 | union |
154 | { |
155 | const Elf32_Word *l_gnu_buckets; |
156 | const Elf_Symndx *l_chain; |
157 | }; |
158 | union |
159 | { |
160 | const Elf32_Word *l_gnu_chain_zero; |
161 | const Elf_Symndx *l_buckets; |
162 | }; |
163 | |
164 | unsigned int l_direct_opencount; /* Reference count for dlopen/dlclose. */ |
165 | enum /* Where this object came from. */ |
166 | { |
167 | lt_executable, /* The main executable program. */ |
168 | lt_library, /* Library needed by main executable. */ |
169 | lt_loaded /* Extra run-time loaded shared object. */ |
170 | } l_type:2; |
171 | unsigned int l_relocated:1; /* Nonzero if object's relocations done. */ |
172 | unsigned int l_init_called:1; /* Nonzero if DT_INIT function called. */ |
173 | unsigned int l_global:1; /* Nonzero if object in _dl_global_scope. */ |
174 | unsigned int l_reserved:2; /* Reserved for internal use. */ |
175 | unsigned int l_phdr_allocated:1; /* Nonzero if the data structure pointed |
176 | to by `l_phdr' is allocated. */ |
177 | unsigned int l_soname_added:1; /* Nonzero if the SONAME is for sure in |
178 | the l_libname list. */ |
179 | unsigned int l_faked:1; /* Nonzero if this is a faked descriptor |
180 | without associated file. */ |
181 | unsigned int l_need_tls_init:1; /* Nonzero if GL(dl_init_static_tls) |
182 | should be called on this link map |
183 | when relocation finishes. */ |
184 | unsigned int l_auditing:1; /* Nonzero if the DSO is used in auditing. */ |
185 | unsigned int l_audit_any_plt:1; /* Nonzero if at least one audit module |
186 | is interested in the PLT interception.*/ |
187 | unsigned int l_removed:1; /* Nozero if the object cannot be used anymore |
188 | since it is removed. */ |
189 | unsigned int l_contiguous:1; /* Nonzero if inter-segment holes are |
190 | mprotected or if no holes are present at |
191 | all. */ |
192 | unsigned int l_symbolic_in_local_scope:1; /* Nonzero if l_local_scope |
193 | during LD_TRACE_PRELINKING=1 |
194 | contains any DT_SYMBOLIC |
195 | libraries. */ |
196 | unsigned int l_free_initfini:1; /* Nonzero if l_initfini can be |
197 | freed, ie. not allocated with |
198 | the dummy malloc in ld.so. */ |
199 | |
200 | /* Collected information about own RPATH directories. */ |
201 | struct r_search_path_struct l_rpath_dirs; |
202 | |
203 | /* Collected results of relocation while profiling. */ |
204 | struct reloc_result |
205 | { |
206 | DL_FIXUP_VALUE_TYPE addr; |
207 | struct link_map *bound; |
208 | unsigned int boundndx; |
209 | uint32_t enterexit; |
210 | unsigned int flags; |
211 | } *l_reloc_result; |
212 | |
213 | /* Pointer to the version information if available. */ |
214 | ElfW(Versym) *l_versyms; |
215 | |
216 | /* String specifying the path where this object was found. */ |
217 | const char *l_origin; |
218 | |
219 | /* Start and finish of memory map for this object. l_map_start |
220 | need not be the same as l_addr. */ |
221 | ElfW(Addr) l_map_start, l_map_end; |
222 | /* End of the executable part of the mapping. */ |
223 | ElfW(Addr) l_text_end; |
224 | |
225 | /* Default array for 'l_scope'. */ |
226 | struct r_scope_elem *l_scope_mem[4]; |
227 | /* Size of array allocated for 'l_scope'. */ |
228 | size_t l_scope_max; |
229 | /* This is an array defining the lookup scope for this link map. |
230 | There are initially at most three different scope lists. */ |
231 | struct r_scope_elem **l_scope; |
232 | |
233 | /* A similar array, this time only with the local scope. This is |
234 | used occasionally. */ |
235 | struct r_scope_elem *l_local_scope[2]; |
236 | |
237 | /* This information is kept to check for sure whether a shared |
238 | object is the same as one already loaded. */ |
239 | struct r_file_id l_file_id; |
240 | |
241 | /* Collected information about own RUNPATH directories. */ |
242 | struct r_search_path_struct l_runpath_dirs; |
243 | |
244 | /* List of object in order of the init and fini calls. */ |
245 | struct link_map **l_initfini; |
246 | |
247 | /* List of the dependencies introduced through symbol binding. */ |
248 | struct link_map_reldeps |
249 | { |
250 | unsigned int act; |
251 | struct link_map *list[]; |
252 | } *l_reldeps; |
253 | unsigned int l_reldepsmax; |
254 | |
255 | /* Nonzero if the DSO is used. */ |
256 | unsigned int l_used; |
257 | |
258 | /* Various flag words. */ |
259 | ElfW(Word) l_feature_1; |
260 | ElfW(Word) l_flags_1; |
261 | ElfW(Word) l_flags; |
262 | |
263 | /* Temporarily used in `dl_close'. */ |
264 | int l_idx; |
265 | |
266 | struct link_map_machine l_mach; |
267 | |
268 | struct |
269 | { |
270 | const ElfW(Sym) *sym; |
271 | int type_class; |
272 | struct link_map *value; |
273 | const ElfW(Sym) *ret; |
274 | } l_lookup_cache; |
275 | |
276 | /* Thread-local storage related info. */ |
277 | |
278 | /* Start of the initialization image. */ |
279 | void *l_tls_initimage; |
280 | /* Size of the initialization image. */ |
281 | size_t l_tls_initimage_size; |
282 | /* Size of the TLS block. */ |
283 | size_t l_tls_blocksize; |
284 | /* Alignment requirement of the TLS block. */ |
285 | size_t l_tls_align; |
286 | /* Offset of first byte module alignment. */ |
287 | size_t l_tls_firstbyte_offset; |
288 | #ifndef NO_TLS_OFFSET |
289 | # define NO_TLS_OFFSET 0 |
290 | #endif |
291 | #ifndef FORCED_DYNAMIC_TLS_OFFSET |
292 | # if NO_TLS_OFFSET == 0 |
293 | # define FORCED_DYNAMIC_TLS_OFFSET -1 |
294 | # elif NO_TLS_OFFSET == -1 |
295 | # define FORCED_DYNAMIC_TLS_OFFSET -2 |
296 | # else |
297 | # error "FORCED_DYNAMIC_TLS_OFFSET is not defined" |
298 | # endif |
299 | #endif |
300 | /* For objects present at startup time: offset in the static TLS block. */ |
301 | ptrdiff_t l_tls_offset; |
302 | /* Index of the module in the dtv array. */ |
303 | size_t l_tls_modid; |
304 | |
305 | /* Number of thread_local objects constructed by this DSO. This is |
306 | atomically accessed and modified and is not always protected by the load |
307 | lock. See also: CONCURRENCY NOTES in cxa_thread_atexit_impl.c. */ |
308 | size_t l_tls_dtor_count; |
309 | |
310 | /* Information used to change permission after the relocations are |
311 | done. */ |
312 | ElfW(Addr) l_relro_addr; |
313 | size_t l_relro_size; |
314 | |
315 | unsigned long long int l_serial; |
316 | |
317 | /* Audit information. This array apparent must be the last in the |
318 | structure. Never add something after it. */ |
319 | struct auditstate |
320 | { |
321 | uintptr_t cookie; |
322 | unsigned int bindflags; |
323 | } l_audit[0]; |
324 | }; |
325 | |
326 | |
327 | #if __ELF_NATIVE_CLASS == 32 |
328 | # define symbind symbind32 |
329 | #elif __ELF_NATIVE_CLASS == 64 |
330 | # define symbind symbind64 |
331 | #else |
332 | # error "__ELF_NATIVE_CLASS must be defined" |
333 | #endif |
334 | |
335 | extern int __dl_iterate_phdr (int (*callback) (struct dl_phdr_info *info, |
336 | size_t size, void *data), |
337 | void *data); |
338 | |
339 | /* We use this macro to refer to ELF macros independent of the native |
340 | wordsize. `ELFW(R_TYPE)' is used in place of `ELF32_R_TYPE' or |
341 | `ELF64_R_TYPE'. */ |
342 | #define ELFW(type) _ElfW (ELF, __ELF_NATIVE_CLASS, type) |
343 | |
344 | #endif /* include/link.h */ |
345 | |