2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 #ifndef RTLD_H /* { */
31 #include <machine/elf.h>
32 #include <sys/types.h>
33 #include <sys/queue.h>
35 #include <elf-hints.h>
41 #include "rtld_lock.h"
42 #include "rtld_machdep.h"
44 #define NEW(type) ((type *) xmalloc(sizeof(type)))
45 #define CNEW(type) ((type *) xcalloc(1, sizeof(type)))
47 /* We might as well do booleans like C++. */
48 typedef unsigned char bool;
52 extern size_t tls_last_offset;
53 extern size_t tls_last_size;
54 extern size_t tls_static_space;
55 extern int tls_dtv_generation;
56 extern int tls_max_index;
58 extern int npagesizes;
59 extern size_t *pagesizes;
62 extern char **main_argv;
63 extern char **environ;
66 struct Struct_Obj_Entry;
68 /* Lists of shared objects */
69 typedef struct Struct_Objlist_Entry {
70 STAILQ_ENTRY(Struct_Objlist_Entry) link;
71 struct Struct_Obj_Entry *obj;
74 typedef STAILQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
76 /* Types of init and fini functions */
77 typedef void (*InitFunc)(void);
78 typedef void (*InitArrFunc)(int, char **, char **);
80 /* Lists of shared object dependencies */
81 typedef struct Struct_Needed_Entry {
82 struct Struct_Needed_Entry *next;
83 struct Struct_Obj_Entry *obj;
84 unsigned long name; /* Offset of name in string table */
87 typedef struct Struct_Name_Entry {
88 STAILQ_ENTRY(Struct_Name_Entry) link;
93 typedef struct Struct_LockInfo {
94 void *context; /* Client context for creating locks */
95 void *thelock; /* The one big lock */
97 volatile int rcount; /* Number of readers holding lock */
98 volatile int wcount; /* Number of writers holding lock */
100 void *(*lock_create)(void *context);
101 void (*rlock_acquire)(void *lock);
102 void (*wlock_acquire)(void *lock);
103 void (*rlock_release)(void *lock);
104 void (*wlock_release)(void *lock);
105 void (*lock_destroy)(void *lock);
106 void (*context_destroy)(void *context);
109 typedef struct Struct_Ver_Entry {
116 typedef struct Struct_Sym_Match_Result {
117 const Elf_Sym *sym_out;
118 const Elf_Sym *vsymp;
122 #define VER_INFO_HIDDEN 0x01
125 * Shared object descriptor.
127 * Items marked with "(%)" are dynamically allocated, and must be freed
128 * when the structure is destroyed.
130 * CAUTION: It appears that the JDK port peeks into these structures.
131 * It looks at "next" and "mapbase" at least. Don't add new members
132 * near the front, until this can be straightened out.
134 typedef struct Struct_Obj_Entry {
136 * These two items have to be set right for compatibility with the
137 * original ElfKit crt1.o.
139 Elf_Size magic; /* Magic number (sanity check) */
140 Elf_Size version; /* Version number of struct format */
142 struct Struct_Obj_Entry *next;
143 char *path; /* Pathname of underlying file (%) */
144 char *origin_path; /* Directory path of origin file */
146 int dl_refcount; /* Number of times loaded by dlopen */
148 /* These items are computed by map_object() or by digest_phdr(). */
149 caddr_t mapbase; /* Base address of mapped region */
150 size_t mapsize; /* Size of mapped region in bytes */
151 size_t textsize; /* Size of text segment in bytes */
152 Elf_Addr vaddrbase; /* Base address in shared object file */
153 caddr_t relocbase; /* Relocation constant = mapbase - vaddrbase */
154 const Elf_Dyn *dynamic; /* Dynamic section */
155 caddr_t entry; /* Entry point */
156 const Elf_Phdr *phdr; /* Program header if it is mapped, else NULL */
157 size_t phsize; /* Size of program header in bytes */
158 const char *interp; /* Pathname of the interpreter, if any */
159 Elf_Word stack_flags;
161 /* TLS information */
162 int tlsindex; /* Index in DTV for this module */
163 void *tlsinit; /* Base address of TLS init block */
164 size_t tlsinitsize; /* Size of TLS init block for this module */
165 size_t tlssize; /* Size of TLS block for this module */
166 size_t tlsoffset; /* Offset of static TLS block for this module */
167 size_t tlsalign; /* Alignment of static TLS block */
172 /* Items from the dynamic section. */
173 Elf_Addr *pltgot; /* PLT or GOT, depending on architecture */
174 const Elf_Rel *rel; /* Relocation entries */
175 unsigned long relsize; /* Size in bytes of relocation info */
176 const Elf_Rela *rela; /* Relocation entries with addend */
177 unsigned long relasize; /* Size in bytes of addend relocation info */
178 const Elf_Rel *pltrel; /* PLT relocation entries */
179 unsigned long pltrelsize; /* Size in bytes of PLT relocation info */
180 const Elf_Rela *pltrela; /* PLT relocation entries with addend */
181 unsigned long pltrelasize; /* Size in bytes of PLT addend reloc info */
182 const Elf_Sym *symtab; /* Symbol table */
183 const char *strtab; /* String table */
184 unsigned long strsize; /* Size in bytes of string table */
186 Elf_Word local_gotno; /* Number of local GOT entries */
187 Elf_Word symtabno; /* Number of dynamic symbols */
188 Elf_Word gotsym; /* First dynamic symbol in GOT */
191 const Elf_Verneed *verneed; /* Required versions. */
192 Elf_Word verneednum; /* Number of entries in verneed table */
193 const Elf_Verdef *verdef; /* Provided versions. */
194 Elf_Word verdefnum; /* Number of entries in verdef table */
195 const Elf_Versym *versyms; /* Symbol versions table */
197 const Elf_Hashelt *buckets; /* Hash table buckets array */
198 unsigned long nbuckets; /* Number of buckets */
199 const Elf_Hashelt *chains; /* Hash table chain array */
200 unsigned long nchains; /* Number of entries in chain array */
202 Elf32_Word nbuckets_gnu; /* Number of GNU hash buckets*/
203 Elf32_Word symndx_gnu; /* 1st accessible symbol on dynsym table */
204 Elf32_Word maskwords_bm_gnu; /* Bloom filter words - 1 (bitmask) */
205 Elf32_Word shift2_gnu; /* Bloom filter shift count */
206 Elf32_Word dynsymcount; /* Total entries in dynsym table */
207 Elf_Addr *bloom_gnu; /* Bloom filter used by GNU hash func */
208 const Elf_Hashelt *buckets_gnu; /* GNU hash table bucket array */
209 const Elf_Hashelt *chain_zero_gnu; /* GNU hash table value array (Zeroed) */
211 char *rpath; /* Search path specified in object */
212 char *runpath; /* Search path with different priority */
213 Needed_Entry *needed; /* Shared objects needed by this one (%) */
214 Needed_Entry *needed_filtees;
215 Needed_Entry *needed_aux_filtees;
217 STAILQ_HEAD(, Struct_Name_Entry) names; /* List of names for this object we
219 Ver_Entry *vertab; /* Versions required /defined by this object */
220 int vernum; /* Number of entries in vertab */
222 Elf_Addr init; /* Initialization function to call */
223 Elf_Addr fini; /* Termination function to call */
224 Elf_Addr preinit_array; /* Pre-initialization array of functions */
225 Elf_Addr init_array; /* Initialization array of functions */
226 Elf_Addr fini_array; /* Termination array of functions */
227 int preinit_array_num; /* Number of entries in preinit_array */
228 int init_array_num; /* Number of entries in init_array */
229 int fini_array_num; /* Number of entries in fini_array */
231 int32_t osrel; /* OSREL note value */
233 bool mainprog : 1; /* True if this is the main program */
234 bool rtld : 1; /* True if this is the dynamic linker */
235 bool relocated : 1; /* True if processed by relocate_objects() */
236 bool ver_checked : 1; /* True if processed by rtld_verify_object_versions */
237 bool textrel : 1; /* True if there are relocations to text seg */
238 bool symbolic : 1; /* True if generated with "-Bsymbolic" */
239 bool bind_now : 1; /* True if all relocations should be made first */
240 bool traced : 1; /* Already printed in ldd trace output */
241 bool jmpslots_done : 1; /* Already have relocated the jump slots */
242 bool init_done : 1; /* Already have added object to init list */
243 bool tls_done : 1; /* Already allocated offset for static TLS */
244 bool phdr_alloc : 1; /* Phdr is allocated and needs to be freed. */
245 bool z_origin : 1; /* Process rpath and soname tokens */
246 bool z_nodelete : 1; /* Do not unload the object and dependencies */
247 bool z_noopen : 1; /* Do not load on dlopen */
248 bool z_loadfltr : 1; /* Immediately load filtees */
249 bool z_interpose : 1; /* Interpose all objects but main */
250 bool z_nodeflib : 1; /* Don't search default library path */
251 bool z_global : 1; /* Make the object global */
252 bool ref_nodel : 1; /* Refcount increased to prevent dlclose */
253 bool init_scanned: 1; /* Object is already on init list. */
254 bool on_fini_list: 1; /* Object is already on fini list. */
255 bool dag_inited : 1; /* Object has its DAG initialized. */
256 bool filtees_loaded : 1; /* Filtees loaded */
257 bool irelative : 1; /* Object has R_MACHDEP_IRELATIVE relocs */
258 bool gnu_ifunc : 1; /* Object has references to STT_GNU_IFUNC */
259 bool non_plt_gnu_ifunc : 1; /* Object has non-plt IFUNC references */
260 bool crt_no_init : 1; /* Object' crt does not call _init/_fini */
261 bool valid_hash_sysv : 1; /* A valid System V hash hash tag is available */
262 bool valid_hash_gnu : 1; /* A valid GNU hash tag is available */
263 bool dlopened : 1; /* dlopen()-ed (vs. load statically) */
265 struct link_map linkmap; /* For GDB and dlinfo() */
266 Objlist dldags; /* Object belongs to these dlopened DAGs (%) */
267 Objlist dagmembers; /* DAG has these members (%) */
268 dev_t dev; /* Object's filesystem's device */
269 ino_t ino; /* Object's inode number */
270 void *priv; /* Platform-dependent */
273 #define RTLD_MAGIC 0xd550b87a
274 #define RTLD_VERSION 1
276 #define RTLD_STATIC_TLS_EXTRA 128
278 /* Flags to be passed into symlook_ family of functions. */
279 #define SYMLOOK_IN_PLT 0x01 /* Lookup for PLT symbol */
280 #define SYMLOOK_DLSYM 0x02 /* Return newest versioned symbol. Used by
282 #define SYMLOOK_EARLY 0x04 /* Symlook is done during initialization. */
283 #define SYMLOOK_IFUNC 0x08 /* Allow IFUNC processing in
286 /* Flags for load_object(). */
287 #define RTLD_LO_NOLOAD 0x01 /* dlopen() specified RTLD_NOLOAD. */
288 #define RTLD_LO_DLOPEN 0x02 /* Load_object() called from dlopen(). */
289 #define RTLD_LO_TRACE 0x04 /* Only tracing. */
290 #define RTLD_LO_NODELETE 0x08 /* Loaded object cannot be closed. */
291 #define RTLD_LO_FILTEES 0x10 /* Loading filtee. */
292 #define RTLD_LO_EARLY 0x20 /* Do not call ctors, postpone it to the
293 initialization during the image start. */
296 * Symbol cache entry used during relocation to avoid multiple lookups
297 * of the same symbol.
299 typedef struct Struct_SymCache {
300 const Elf_Sym *sym; /* Symbol table entry */
301 const Obj_Entry *obj; /* Shared object which defines it */
305 * This structure provides a reentrant way to keep a list of objects and
306 * check which ones have already been processed in some way.
308 typedef struct Struct_DoneList {
309 const Obj_Entry **objs; /* Array of object pointers */
310 unsigned int num_alloc; /* Allocated size of the array */
311 unsigned int num_used; /* Number of array slots used */
314 struct Struct_RtldLockState {
319 struct fill_search_info_args {
322 struct dl_serinfo *serinfo;
323 struct dl_serpath *serpath;
328 * The pack of arguments and results for the symbol lookup functions.
330 typedef struct Struct_SymLook {
334 const Ver_Entry *ventry;
336 const Obj_Entry *defobj_out;
337 const Elf_Sym *sym_out;
338 struct Struct_RtldLockState *lockstate;
341 void _rtld_error(const char *, ...) __printflike(1, 2) __exported;
342 void rtld_die(void) __dead2;
343 const char *rtld_strerror(int);
344 Obj_Entry *map_object(int, const char *, const struct stat *);
345 void *xcalloc(size_t, size_t);
346 void *xmalloc(size_t);
347 char *xstrdup(const char *);
348 void *malloc_aligned(size_t size, size_t align);
349 void free_aligned(void *ptr);
350 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
351 extern Elf_Sym sym_zero; /* For resolving undefined weak refs. */
353 void dump_relocations(Obj_Entry *);
354 void dump_obj_relocations(Obj_Entry *);
355 void dump_Elf_Rel(Obj_Entry *, const Elf_Rel *, u_long);
356 void dump_Elf_Rela(Obj_Entry *, const Elf_Rela *, u_long);
359 * Function declarations.
361 unsigned long elf_hash(const char *);
362 const Elf_Sym *find_symdef(unsigned long, const Obj_Entry *,
363 const Obj_Entry **, int, SymCache *, struct Struct_RtldLockState *);
364 void init_pltgot(Obj_Entry *);
365 void lockdflt_init(void);
366 void digest_notes(Obj_Entry *, Elf_Addr, Elf_Addr);
367 void obj_free(Obj_Entry *);
368 Obj_Entry *obj_new(void);
369 void _rtld_bind_start(void);
370 void *rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def);
371 void symlook_init(SymLook *, const char *);
372 int symlook_obj(SymLook *, const Obj_Entry *);
373 void *tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset);
374 void *allocate_tls(Obj_Entry *, void *, size_t, size_t);
375 void free_tls(void *, size_t, size_t);
376 void *allocate_module_tls(int index);
377 bool allocate_tls_offset(Obj_Entry *obj);
378 void free_tls_offset(Obj_Entry *obj);
379 const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long);
382 * MD function declarations.
384 int do_copy_relocations(Obj_Entry *);
385 int reloc_non_plt(Obj_Entry *, Obj_Entry *, int flags,
386 struct Struct_RtldLockState *);
387 int reloc_plt(Obj_Entry *);
388 int reloc_jmpslots(Obj_Entry *, int flags, struct Struct_RtldLockState *);
389 int reloc_iresolve(Obj_Entry *, struct Struct_RtldLockState *);
390 int reloc_gnu_ifunc(Obj_Entry *, int flags, struct Struct_RtldLockState *);
391 void allocate_initial_tls(Obj_Entry *);