lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame] | 1 | /* Data structure for communication from the run-time dynamic linker for |
| 2 | loaded ELF shared objects. |
| 3 | Copyright (C) 1995-2015 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 <bits/linkmap.h> |
| 43 | #include <dl-fileid.h> |
| 44 | #include <dl-lookupcfg.h> |
| 45 | #include <tls.h> |
| 46 | #include <bits/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 */ |