rtld.h revision 1.95
1 /* $NetBSD: rtld.h,v 1.95 2010/10/16 10:27:07 skrll Exp $ */ 2 3 /* 4 * Copyright 1996 John D. Polstra. 5 * Copyright 1996 Matt Thomas <matt (at) 3am-software.com> 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by John Polstra. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 #ifndef RTLD_H 35 #define RTLD_H 36 37 #include <dlfcn.h> 38 #include <stdbool.h> 39 #include <stddef.h> 40 #include <sys/param.h> 41 #include <sys/types.h> 42 #include <sys/queue.h> 43 #include <sys/exec_elf.h> 44 #include "rtldenv.h" 45 #include "link.h" 46 47 #if defined(_RTLD_SOURCE) 48 49 #ifndef RTLD_DEFAULT_LIBRARY_PATH 50 #define RTLD_DEFAULT_LIBRARY_PATH "/usr/lib" 51 #endif 52 #define _PATH_LD_HINTS "/etc/ld.so.conf" 53 54 extern size_t _rtld_pagesz; 55 56 #define round_down(x) ((x) & ~(_rtld_pagesz - 1)) 57 #define round_up(x) round_down((x) + _rtld_pagesz - 1) 58 59 #define NEW(type) ((type *) xmalloc(sizeof(type))) 60 #define CNEW(type) ((type *) xcalloc(sizeof(type))) 61 62 /* 63 * Fill in a DoneList with an allocation large enough to hold all of 64 * the currently-loaded objects. Keep this in a macro since it calls 65 * alloca and we want that to occur within the scope of the caller. 66 */ 67 #define _rtld_donelist_init(dlp) \ 68 ((dlp)->num_alloc = _rtld_objcount, \ 69 (dlp)->objs = alloca((dlp)->num_alloc * sizeof((dlp)->objs[0])), \ 70 assert((dlp)->objs != NULL), \ 71 (dlp)->num_used = 0) 72 73 #endif /* _RTLD_SOURCE */ 74 75 /* 76 * C++ has mandated the use of the following keywords for its new boolean 77 * type. We might as well follow their lead. 78 */ 79 struct Struct_Obj_Entry; 80 81 typedef struct Struct_Objlist_Entry { 82 SIMPLEQ_ENTRY(Struct_Objlist_Entry) link; 83 struct Struct_Obj_Entry *obj; 84 } Objlist_Entry; 85 86 typedef SIMPLEQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist; 87 88 typedef struct Struct_Name_Entry { 89 STAILQ_ENTRY(Struct_Name_Entry) link; 90 char name[1]; 91 } Name_Entry; 92 93 typedef struct Struct_Needed_Entry { 94 struct Struct_Needed_Entry *next; 95 struct Struct_Obj_Entry *obj; 96 unsigned long name; /* Offset of name in string table */ 97 } Needed_Entry; 98 99 typedef struct _rtld_search_path_t { 100 struct _rtld_search_path_t *sp_next; 101 const char *sp_path; 102 size_t sp_pathlen; 103 } Search_Path; 104 105 106 #define RTLD_MAX_ENTRY 10 107 #define RTLD_MAX_LIBRARY 4 108 #define RTLD_MAX_CTL 2 109 typedef struct _rtld_library_xform_t { 110 struct _rtld_library_xform_t *next; 111 char *name; 112 const char *ctlname; 113 struct { 114 char *value; 115 char *library[RTLD_MAX_LIBRARY]; 116 } entry[RTLD_MAX_ENTRY]; 117 } Library_Xform; 118 119 /* 120 * Shared object descriptor. 121 * 122 * Items marked with "(%)" are dynamically allocated, and must be freed 123 * when the structure is destroyed. 124 * 125 * The layout of this structure needs to be preserved because pre-2.0 binaries 126 * hard-coded the location of dlopen() and friends. 127 */ 128 129 #define RTLD_MAGIC 0xd550b87a 130 #define RTLD_VERSION 1 131 #define RTLD_MAIN 0x800 132 133 typedef struct Struct_Obj_Entry { 134 Elf32_Word magic; /* Magic number (sanity check) */ 135 Elf32_Word version; /* Version number of struct format */ 136 137 struct Struct_Obj_Entry *next; 138 char *path; /* Pathname of underlying file (%) */ 139 int refcount; 140 int dl_refcount; /* Number of times loaded by dlopen */ 141 142 /* These items are computed by map_object() or by digest_phdr(). */ 143 caddr_t mapbase; /* Base address of mapped region */ 144 size_t mapsize; /* Size of mapped region in bytes */ 145 size_t textsize; /* Size of text segment in bytes */ 146 Elf_Addr vaddrbase; /* Base address in shared object file */ 147 caddr_t relocbase; /* Reloc const = mapbase - *vaddrbase */ 148 Elf_Dyn *dynamic; /* Dynamic section */ 149 caddr_t entry; /* Entry point */ 150 const Elf_Phdr *phdr; /* Program header (may be xmalloc'ed) */ 151 size_t phsize; /* Size of program header in bytes */ 152 153 /* Items from the dynamic section. */ 154 Elf_Addr *pltgot; /* PLTGOT table */ 155 const Elf_Rel *rel; /* Relocation entries */ 156 const Elf_Rel *rellim; /* Limit of Relocation entries */ 157 const Elf_Rela *rela; /* Relocation entries */ 158 const Elf_Rela *relalim; /* Limit of Relocation entries */ 159 const Elf_Rel *pltrel; /* PLT relocation entries */ 160 const Elf_Rel *pltrellim; /* Limit of PLT relocation entries */ 161 const Elf_Rela *pltrela; /* PLT relocation entries */ 162 const Elf_Rela *pltrelalim; /* Limit of PLT relocation entries */ 163 const Elf_Sym *symtab; /* Symbol table */ 164 const char *strtab; /* String table */ 165 unsigned long strsize; /* Size in bytes of string table */ 166 #ifdef __mips__ 167 Elf_Word local_gotno; /* Number of local GOT entries */ 168 Elf_Word symtabno; /* Number of dynamic symbols */ 169 Elf_Word gotsym; /* First dynamic symbol in GOT */ 170 #endif 171 172 const Elf_Symindx *buckets; /* Hash table buckets array */ 173 unsigned long unused1; /* Used to be nbuckets */ 174 const Elf_Symindx *chains; /* Hash table chain array */ 175 unsigned long nchains; /* Number of chains */ 176 177 Search_Path *rpaths; /* Search path specified in object */ 178 Needed_Entry *needed; /* Shared objects needed by this (%) */ 179 180 void (*init)(void); /* Initialization function to call */ 181 void (*fini)(void); /* Termination function to call */ 182 183 /* Entry points for dlopen() and friends. */ 184 void *(*dlopen)(const char *, int); 185 void *(*dlsym)(void *, const char *); 186 char *(*dlerror)(void); 187 int (*dlclose)(void *); 188 int (*dladdr)(const void *, Dl_info *); 189 190 u_int32_t mainprog:1, /* True if this is the main program */ 191 rtld:1, /* True if this is the dynamic linker */ 192 textrel:1, /* True if there are relocations to 193 * text seg */ 194 symbolic:1, /* True if generated with 195 * "-Bsymbolic" */ 196 printed:1, /* True if ldd has printed it */ 197 isdynamic:1, /* True if this is a pure PIC object */ 198 mainref:1, /* True if on _rtld_list_main */ 199 globalref:1, /* True if on _rtld_list_global */ 200 init_done:1, /* True if .init has been added */ 201 init_called:1, /* True if .init function has been 202 * called */ 203 fini_called:1, /* True if .fini function has been 204 * called */ 205 initfirst:1, /* True if object's .init/.fini take 206 * priority over others */ 207 phdr_loaded:1; /* Phdr is loaded and doesn't need to 208 * be freed. */ 209 210 struct link_map linkmap; /* for GDB */ 211 212 /* These items are computed by map_object() or by digest_phdr(). */ 213 const char *interp; /* Pathname of the interpreter, if any */ 214 Objlist dldags; /* Object belongs to these dlopened DAGs (%) */ 215 Objlist dagmembers; /* DAG has these members (%) */ 216 dev_t dev; /* Object's filesystem's device */ 217 ino_t ino; /* Object's inode number */ 218 219 void *ehdr; 220 221 uint32_t nbuckets; /* Number of buckets */ 222 uint32_t nbuckets_m; /* Precomputed for fast remainder */ 223 uint8_t nbuckets_s1; 224 uint8_t nbuckets_s2; 225 size_t pathlen; /* Pathname length */ 226 STAILQ_HEAD(, Struct_Name_Entry) names; /* List of names for this object we 227 know about. */ 228 } Obj_Entry; 229 230 typedef struct Struct_DoneList { 231 const Obj_Entry **objs; /* Array of object pointers */ 232 unsigned int num_alloc; /* Allocated size of the array */ 233 unsigned int num_used; /* Number of array slots used */ 234 } DoneList; 235 236 237 #if defined(_RTLD_SOURCE) 238 239 extern struct r_debug _rtld_debug; 240 extern Search_Path *_rtld_default_paths; 241 extern Obj_Entry *_rtld_objlist; 242 extern Obj_Entry **_rtld_objtail; 243 extern u_int _rtld_objcount; 244 extern u_int _rtld_objloads; 245 extern Obj_Entry *_rtld_objmain; 246 extern Obj_Entry _rtld_objself; 247 extern Search_Path *_rtld_paths; 248 extern Library_Xform *_rtld_xforms; 249 extern bool _rtld_trust; 250 extern Objlist _rtld_list_global; 251 extern Objlist _rtld_list_main; 252 extern Elf_Sym _rtld_sym_zero; 253 254 /* rtld.c */ 255 256 /* We export these symbols using _rtld_symbol_lookup and is_exported. */ 257 char *dlerror(void); 258 void *dlopen(const char *, int); 259 void *dlsym(void *, const char *); 260 int dlclose(void *); 261 int dladdr(const void *, Dl_info *); 262 int dlinfo(void *, int, void *); 263 int dl_iterate_phdr(int (*)(struct dl_phdr_info *, size_t, void *), 264 void *); 265 266 /* These aren't exported */ 267 void _rtld_error(const char *, ...) 268 __attribute__((__format__(__printf__,1,2))); 269 void _rtld_die(void) __attribute__((__noreturn__)); 270 void *_rtld_objmain_sym(const char *); 271 void _rtld_debug_state(void); 272 void _rtld_linkmap_add(Obj_Entry *); 273 void _rtld_linkmap_delete(Obj_Entry *); 274 void _rtld_objlist_push_head(Objlist *, Obj_Entry *); 275 void _rtld_objlist_push_tail(Objlist *, Obj_Entry *); 276 Objlist_Entry *_rtld_objlist_find(Objlist *, const Obj_Entry *); 277 278 /* expand.c */ 279 size_t _rtld_expand_path(char *, size_t, const char *, const char *,\ 280 const char *); 281 282 /* headers.c */ 283 void _rtld_digest_dynamic(const char *, Obj_Entry *); 284 Obj_Entry *_rtld_digest_phdr(const Elf_Phdr *, int, caddr_t); 285 286 /* load.c */ 287 Obj_Entry *_rtld_load_object(const char *, int); 288 int _rtld_load_needed_objects(Obj_Entry *, int); 289 int _rtld_preload(const char *); 290 291 /* path.c */ 292 void _rtld_add_paths(const char *, Search_Path **, const char *); 293 void _rtld_process_hints(const char *, Search_Path **, Library_Xform **, 294 const char *); 295 int _rtld_sysctl(const char *, void *, size_t *); 296 297 /* reloc.c */ 298 int _rtld_do_copy_relocations(const Obj_Entry *); 299 int _rtld_relocate_objects(Obj_Entry *, bool); 300 int _rtld_relocate_nonplt_objects(Obj_Entry *); 301 int _rtld_relocate_plt_lazy(const Obj_Entry *); 302 int _rtld_relocate_plt_objects(const Obj_Entry *); 303 void _rtld_setup_pltgot(const Obj_Entry *); 304 305 /* search.c */ 306 Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int); 307 308 /* symbol.c */ 309 unsigned long _rtld_elf_hash(const char *); 310 const Elf_Sym *_rtld_symlook_obj(const char *, unsigned long, 311 const Obj_Entry *, bool); 312 const Elf_Sym *_rtld_find_symdef(unsigned long, const Obj_Entry *, 313 const Obj_Entry **, bool); 314 const Elf_Sym *_rtld_find_plt_symdef(unsigned long, const Obj_Entry *, 315 const Obj_Entry **, bool); 316 317 const Elf_Sym *_rtld_symlook_list(const char *, unsigned long, 318 const Objlist *, const Obj_Entry **, bool, DoneList *); 319 const Elf_Sym *_rtld_symlook_default(const char *, unsigned long, 320 const Obj_Entry *, const Obj_Entry **, bool); 321 const Elf_Sym *_rtld_symlook_needed(const char *, unsigned long, 322 const Needed_Entry *, const Obj_Entry **, bool, 323 DoneList *, DoneList *); 324 #ifdef COMBRELOC 325 void _rtld_combreloc_reset(const Obj_Entry *); 326 #endif 327 328 /* map_object.c */ 329 struct stat; 330 Obj_Entry *_rtld_map_object(const char *, int, const struct stat *); 331 void _rtld_obj_free(Obj_Entry *); 332 Obj_Entry *_rtld_obj_new(void); 333 334 /* function descriptors */ 335 #ifdef __HAVE_FUNCTION_DESCRIPTORS 336 Elf_Addr _rtld_function_descriptor_alloc(const Obj_Entry *, 337 const Elf_Sym *, Elf_Addr); 338 const void *_rtld_function_descriptor_function(const void *); 339 #endif /* __HAVE_FUNCTION_DESCRIPTORS */ 340 341 #endif /* _RTLD_SOURCE */ 342 343 #endif /* RTLD_H */ 344
Indexes created Tue Sep 30 17:09:57 GMT 2025