1/* Data structure for communication from the run-time dynamic linker for
2 loaded ELF shared objects.
3 Copyright (C) 1995-2020 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 <https://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# ifndef _ISOMAC
28/* Get most of the contents from the public header, but we define a
29 different `struct link_map' type for private use. The la_objopen
30 prototype uses the type, so we have to declare it separately. */
31# define link_map link_map_public
32# define la_objopen la_objopen_wrongproto
33# endif
34
35#include <elf/link.h>
36
37# ifndef _ISOMAC
38
39#undef link_map
40#undef la_objopen
41
42struct link_map;
43extern unsigned int la_objopen (struct link_map *__map, Lmid_t __lmid,
44 uintptr_t *__cookie);
45
46#include <stdint.h>
47#include <stddef.h>
48#include <linkmap.h>
49#include <dl-fileid.h>
50#include <dl-lookupcfg.h>
51#include <tls.h>
52#include <libc-lock.h>
53
54
55/* Some internal data structures of the dynamic linker used in the
56 linker map. We only provide forward declarations. */
57struct libname_list;
58struct r_found_version;
59struct r_search_path_elem;
60
61/* Forward declaration. */
62struct link_map;
63
64/* Structure to describe a single list of scope elements. The lookup
65 functions get passed an array of pointers to such structures. */
66struct r_scope_elem
67{
68 /* Array of maps for the scope. */
69 struct link_map **r_list;
70 /* Number of entries in the scope. */
71 unsigned int r_nlist;
72};
73
74
75/* Structure to record search path and allocation mechanism. */
76struct r_search_path_struct
77 {
78 struct r_search_path_elem **dirs;
79 int malloced;
80 };
81
82/* Structure describing a loaded shared object. The `l_next' and `l_prev'
83 members form a chain of all the shared objects loaded at startup.
84
85 These data structures exist in space used by the run-time dynamic linker;
86 modifying them may have disastrous results.
87
88 This data structure might change in future, if necessary. User-level
89 programs must avoid defining objects of this type. */
90
91struct link_map
92 {
93 /* These first few members are part of the protocol with the debugger.
94 This is the same format used in SVR4. */
95
96 ElfW(Addr) l_addr; /* Difference between the address in the ELF
97 file and the addresses in memory. */
98 char *l_name; /* Absolute file name object was found in. */
99 ElfW(Dyn) *l_ld; /* Dynamic section of the shared object. */
100 struct link_map *l_next, *l_prev; /* Chain of loaded objects. */
101
102 /* All following members are internal to the dynamic linker.
103 They may change without notice. */
104
105 /* This is an element which is only ever different from a pointer to
106 the very same copy of this type for ld.so when it is used in more
107 than one namespace. */
108 struct link_map *l_real;
109
110 /* Number of the namespace this link map belongs to. */
111 Lmid_t l_ns;
112
113 struct libname_list *l_libname;
114 /* Indexed pointers to dynamic section.
115 [0,DT_NUM) are indexed by the processor-independent tags.
116 [DT_NUM,DT_NUM+DT_THISPROCNUM) are indexed by the tag minus DT_LOPROC.
117 [DT_NUM+DT_THISPROCNUM,DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM) are
118 indexed by DT_VERSIONTAGIDX(tagvalue).
119 [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM,
120 DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM) are indexed by
121 DT_EXTRATAGIDX(tagvalue).
122 [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM,
123 DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM) are
124 indexed by DT_VALTAGIDX(tagvalue) and
125 [DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM,
126 DT_NUM+DT_THISPROCNUM+DT_VERSIONTAGNUM+DT_EXTRANUM+DT_VALNUM+DT_ADDRNUM)
127 are indexed by DT_ADDRTAGIDX(tagvalue), see <elf.h>. */
128
129 ElfW(Dyn) *l_info[DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGNUM
130 + DT_EXTRANUM + DT_VALNUM + DT_ADDRNUM];
131 const ElfW(Phdr) *l_phdr; /* Pointer to program header table in core. */
132 ElfW(Addr) l_entry; /* Entry point location. */
133 ElfW(Half) l_phnum; /* Number of program header entries. */
134 ElfW(Half) l_ldnum; /* Number of dynamic segment entries. */
135
136 /* Array of DT_NEEDED dependencies and their dependencies, in
137 dependency order for symbol lookup (with and without
138 duplicates). There is no entry before the dependencies have
139 been loaded. */
140 struct r_scope_elem l_searchlist;
141
142 /* We need a special searchlist to process objects marked with
143 DT_SYMBOLIC. */
144 struct r_scope_elem l_symbolic_searchlist;
145
146 /* Dependent object that first caused this object to be loaded. */
147 struct link_map *l_loader;
148
149 /* Array with version names. */
150 struct r_found_version *l_versions;
151 unsigned int l_nversions;
152
153 /* Symbol hash table. */
154 Elf_Symndx l_nbuckets;
155 Elf32_Word l_gnu_bitmask_idxbits;
156 Elf32_Word l_gnu_shift;
157 const ElfW(Addr) *l_gnu_bitmask;
158 union
159 {
160 const Elf32_Word *l_gnu_buckets;
161 const Elf_Symndx *l_chain;
162 };
163 union
164 {
165 const Elf32_Word *l_gnu_chain_zero;
166 const Elf_Symndx *l_buckets;
167 };
168
169 unsigned int l_direct_opencount; /* Reference count for dlopen/dlclose. */
170 enum /* Where this object came from. */
171 {
172 lt_executable, /* The main executable program. */
173 lt_library, /* Library needed by main executable. */
174 lt_loaded /* Extra run-time loaded shared object. */
175 } l_type:2;
176 unsigned int l_relocated:1; /* Nonzero if object's relocations done. */
177 unsigned int l_init_called:1; /* Nonzero if DT_INIT function called. */
178 unsigned int l_global:1; /* Nonzero if object in _dl_global_scope. */
179 unsigned int l_reserved:2; /* Reserved for internal use. */
180 unsigned int l_phdr_allocated:1; /* Nonzero if the data structure pointed
181 to by `l_phdr' is allocated. */
182 unsigned int l_soname_added:1; /* Nonzero if the SONAME is for sure in
183 the l_libname list. */
184 unsigned int l_faked:1; /* Nonzero if this is a faked descriptor
185 without associated file. */
186 unsigned int l_need_tls_init:1; /* Nonzero if GL(dl_init_static_tls)
187 should be called on this link map
188 when relocation finishes. */
189 unsigned int l_auditing:1; /* Nonzero if the DSO is used in auditing. */
190 unsigned int l_audit_any_plt:1; /* Nonzero if at least one audit module
191 is interested in the PLT interception.*/
192 unsigned int l_removed:1; /* Nozero if the object cannot be used anymore
193 since it is removed. */
194 unsigned int l_contiguous:1; /* Nonzero if inter-segment holes are
195 mprotected or if no holes are present at
196 all. */
197 unsigned int l_symbolic_in_local_scope:1; /* Nonzero if l_local_scope
198 during LD_TRACE_PRELINKING=1
199 contains any DT_SYMBOLIC
200 libraries. */
201 unsigned int l_free_initfini:1; /* Nonzero if l_initfini can be
202 freed, ie. not allocated with
203 the dummy malloc in ld.so. */
204
205 /* NODELETE status of the map. Only valid for maps of type
206 lt_loaded. Lazy binding sets l_nodelete_active directly,
207 potentially from signal handlers. Initial loading of an
208 DF_1_NODELETE object set l_nodelete_pending. Relocation may
209 set l_nodelete_pending as well. l_nodelete_pending maps are
210 promoted to l_nodelete_active status in the final stages of
211 dlopen, prior to calling ELF constructors. dlclose only
212 refuses to unload l_nodelete_active maps, the pending status is
213 ignored. */
214 bool l_nodelete_active;
215 bool l_nodelete_pending;
216
217#include <link_map.h>
218
219 /* Collected information about own RPATH directories. */
220 struct r_search_path_struct l_rpath_dirs;
221
222 /* Collected results of relocation while profiling. */
223 struct reloc_result
224 {
225 DL_FIXUP_VALUE_TYPE addr;
226 struct link_map *bound;
227 unsigned int boundndx;
228 uint32_t enterexit;
229 unsigned int flags;
230 /* CONCURRENCY NOTE: This is used to guard the concurrent initialization
231 of the relocation result across multiple threads. See the more
232 detailed notes in elf/dl-runtime.c. */
233 unsigned int init;
234 } *l_reloc_result;
235
236 /* Pointer to the version information if available. */
237 ElfW(Versym) *l_versyms;
238
239 /* String specifying the path where this object was found. */
240 const char *l_origin;
241
242 /* Start and finish of memory map for this object. l_map_start
243 need not be the same as l_addr. */
244 ElfW(Addr) l_map_start, l_map_end;
245 /* End of the executable part of the mapping. */
246 ElfW(Addr) l_text_end;
247
248 /* Default array for 'l_scope'. */
249 struct r_scope_elem *l_scope_mem[4];
250 /* Size of array allocated for 'l_scope'. */
251 size_t l_scope_max;
252 /* This is an array defining the lookup scope for this link map.
253 There are initially at most three different scope lists. */
254 struct r_scope_elem **l_scope;
255
256 /* A similar array, this time only with the local scope. This is
257 used occasionally. */
258 struct r_scope_elem *l_local_scope[2];
259
260 /* This information is kept to check for sure whether a shared
261 object is the same as one already loaded. */
262 struct r_file_id l_file_id;
263
264 /* Collected information about own RUNPATH directories. */
265 struct r_search_path_struct l_runpath_dirs;
266
267 /* List of object in order of the init and fini calls. */
268 struct link_map **l_initfini;
269
270 /* List of the dependencies introduced through symbol binding. */
271 struct link_map_reldeps
272 {
273 unsigned int act;
274 struct link_map *list[];
275 } *l_reldeps;
276 unsigned int l_reldepsmax;
277
278 /* Nonzero if the DSO is used. */
279 unsigned int l_used;
280
281 /* Various flag words. */
282 ElfW(Word) l_feature_1;
283 ElfW(Word) l_flags_1;
284 ElfW(Word) l_flags;
285
286 /* Temporarily used in `dl_close'. */
287 int l_idx;
288
289 struct link_map_machine l_mach;
290
291 struct
292 {
293 const ElfW(Sym) *sym;
294 int type_class;
295 struct link_map *value;
296 const ElfW(Sym) *ret;
297 } l_lookup_cache;
298
299 /* Thread-local storage related info. */
300
301 /* Start of the initialization image. */
302 void *l_tls_initimage;
303 /* Size of the initialization image. */
304 size_t l_tls_initimage_size;
305 /* Size of the TLS block. */
306 size_t l_tls_blocksize;
307 /* Alignment requirement of the TLS block. */
308 size_t l_tls_align;
309 /* Offset of first byte module alignment. */
310 size_t l_tls_firstbyte_offset;
311#ifndef NO_TLS_OFFSET
312# define NO_TLS_OFFSET 0
313#endif
314#ifndef FORCED_DYNAMIC_TLS_OFFSET
315# if NO_TLS_OFFSET == 0
316# define FORCED_DYNAMIC_TLS_OFFSET -1
317# elif NO_TLS_OFFSET == -1
318# define FORCED_DYNAMIC_TLS_OFFSET -2
319# else
320# error "FORCED_DYNAMIC_TLS_OFFSET is not defined"
321# endif
322#endif
323 /* For objects present at startup time: offset in the static TLS block. */
324 ptrdiff_t l_tls_offset;
325 /* Index of the module in the dtv array. */
326 size_t l_tls_modid;
327
328 /* Number of thread_local objects constructed by this DSO. This is
329 atomically accessed and modified and is not always protected by the load
330 lock. See also: CONCURRENCY NOTES in cxa_thread_atexit_impl.c. */
331 size_t l_tls_dtor_count;
332
333 /* Information used to change permission after the relocations are
334 done. */
335 ElfW(Addr) l_relro_addr;
336 size_t l_relro_size;
337
338 unsigned long long int l_serial;
339 };
340
341/* Information used by audit modules. For most link maps, this data
342 immediate follows the link map in memory. For the dynamic linker,
343 it is allocated separately. See link_map_audit_state in
344 <ldsodefs.h>. */
345struct auditstate
346{
347 uintptr_t cookie;
348 unsigned int bindflags;
349};
350
351
352#if __ELF_NATIVE_CLASS == 32
353# define symbind symbind32
354#elif __ELF_NATIVE_CLASS == 64
355# define symbind symbind64
356#else
357# error "__ELF_NATIVE_CLASS must be defined"
358#endif
359
360extern int __dl_iterate_phdr (int (*callback) (struct dl_phdr_info *info,
361 size_t size, void *data),
362 void *data);
363hidden_proto (__dl_iterate_phdr)
364
365/* We use this macro to refer to ELF macros independent of the native
366 wordsize. `ELFW(R_TYPE)' is used in place of `ELF32_R_TYPE' or
367 `ELF64_R_TYPE'. */
368#define ELFW(type) _ElfW (ELF, __ELF_NATIVE_CLASS, type)
369
370# endif /* !_ISOMAC */
371#endif /* include/link.h */
372