2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
4 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 #ifndef RTLD_H /* { */
33 #include <machine/elf.h>
34 #include <sys/types.h>
35 #include <sys/queue.h>
37 #include <elf-hints.h>
43 #include "rtld_lock.h"
44 #include "rtld_machdep.h"
46 #define NEW(type) ((type *) xmalloc(sizeof(type)))
47 #define CNEW(type) ((type *) xcalloc(1, sizeof(type)))
49 /* We might as well do booleans like C++. */
50 typedef unsigned char bool;
54 extern size_t tls_last_offset;
55 extern size_t tls_last_size;
56 extern size_t tls_static_space;
57 extern Elf_Addr tls_dtv_generation;
58 extern int tls_max_index;
60 extern int npagesizes;
61 extern size_t *pagesizes;
64 extern char **main_argv;
65 extern char **environ;
68 struct Struct_Obj_Entry;
70 /* Lists of shared objects */
71 typedef struct Struct_Objlist_Entry {
72 STAILQ_ENTRY(Struct_Objlist_Entry) link;
73 struct Struct_Obj_Entry *obj;
76 typedef STAILQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
78 /* Types of init and fini functions */
79 typedef void (*InitFunc)(void);
80 typedef void (*InitArrFunc)(int, char **, char **);
82 /* Lists of shared object dependencies */
83 typedef struct Struct_Needed_Entry {
84 struct Struct_Needed_Entry *next;
85 struct Struct_Obj_Entry *obj;
86 unsigned long name; /* Offset of name in string table */
89 typedef struct Struct_Name_Entry {
90 STAILQ_ENTRY(Struct_Name_Entry) link;
95 typedef struct Struct_LockInfo {
96 void *context; /* Client context for creating locks */
97 void *thelock; /* The one big lock */
99 volatile int rcount; /* Number of readers holding lock */
100 volatile int wcount; /* Number of writers holding lock */
102 void *(*lock_create)(void *context);
103 void (*rlock_acquire)(void *lock);
104 void (*wlock_acquire)(void *lock);
105 void (*rlock_release)(void *lock);
106 void (*wlock_release)(void *lock);
107 void (*lock_destroy)(void *lock);
108 void (*context_destroy)(void *context);
111 typedef struct Struct_Ver_Entry {
118 typedef struct Struct_Sym_Match_Result {
119 const Elf_Sym *sym_out;
120 const Elf_Sym *vsymp;
124 #define VER_INFO_HIDDEN 0x01
127 * Shared object descriptor.
129 * Items marked with "(%)" are dynamically allocated, and must be freed
130 * when the structure is destroyed.
132 * CAUTION: It appears that the JDK port peeks into these structures.
133 * It looks at "next" and "mapbase" at least. Don't add new members
134 * near the front, until this can be straightened out.
136 typedef struct Struct_Obj_Entry {
138 * These two items have to be set right for compatibility with the
139 * original ElfKit crt1.o.
141 Elf_Size magic; /* Magic number (sanity check) */
142 Elf_Size version; /* Version number of struct format */
144 TAILQ_ENTRY(Struct_Obj_Entry) next;
145 char *path; /* Pathname of underlying file (%) */
146 char *origin_path; /* Directory path of origin file */
147 int refcount; /* DAG references */
148 int holdcount; /* Count of transient references */
149 int dl_refcount; /* Number of times loaded by dlopen */
151 /* These items are computed by map_object() or by digest_phdr(). */
152 caddr_t mapbase; /* Base address of mapped region */
153 size_t mapsize; /* Size of mapped region in bytes */
154 size_t textsize; /* Size of text segment in bytes */
155 Elf_Addr vaddrbase; /* Base address in shared object file */
156 caddr_t relocbase; /* Relocation constant = mapbase - vaddrbase */
157 const Elf_Dyn *dynamic; /* Dynamic section */
158 caddr_t entry; /* Entry point */
159 const Elf_Phdr *phdr; /* Program header if it is mapped, else NULL */
160 size_t phsize; /* Size of program header in bytes */
161 const char *interp; /* Pathname of the interpreter, if any */
162 Elf_Word stack_flags;
164 /* TLS information */
165 int tlsindex; /* Index in DTV for this module */
166 void *tlsinit; /* Base address of TLS init block */
167 size_t tlsinitsize; /* Size of TLS init block for this module */
168 size_t tlssize; /* Size of TLS block for this module */
169 size_t tlsoffset; /* Offset of static TLS block for this module */
170 size_t tlsalign; /* Alignment of static TLS block */
175 /* Items from the dynamic section. */
176 Elf_Addr *pltgot; /* PLT or GOT, depending on architecture */
177 const Elf_Rel *rel; /* Relocation entries */
178 unsigned long relsize; /* Size in bytes of relocation info */
179 const Elf_Rela *rela; /* Relocation entries with addend */
180 unsigned long relasize; /* Size in bytes of addend relocation info */
181 const Elf_Rel *pltrel; /* PLT relocation entries */
182 unsigned long pltrelsize; /* Size in bytes of PLT relocation info */
183 const Elf_Rela *pltrela; /* PLT relocation entries with addend */
184 unsigned long pltrelasize; /* Size in bytes of PLT addend reloc info */
185 const Elf_Sym *symtab; /* Symbol table */
186 const char *strtab; /* String table */
187 unsigned long strsize; /* Size in bytes of string table */
189 Elf_Word local_gotno; /* Number of local GOT entries */
190 Elf_Word symtabno; /* Number of dynamic symbols */
191 Elf_Word gotsym; /* First dynamic symbol in GOT */
192 Elf_Addr *mips_pltgot; /* Second PLT GOT */
195 Elf_Addr glink; /* GLINK PLT call stub section */
198 const Elf_Verneed *verneed; /* Required versions. */
199 Elf_Word verneednum; /* Number of entries in verneed table */
200 const Elf_Verdef *verdef; /* Provided versions. */
201 Elf_Word verdefnum; /* Number of entries in verdef table */
202 const Elf_Versym *versyms; /* Symbol versions table */
204 const Elf_Hashelt *buckets; /* Hash table buckets array */
205 unsigned long nbuckets; /* Number of buckets */
206 const Elf_Hashelt *chains; /* Hash table chain array */
207 unsigned long nchains; /* Number of entries in chain array */
209 Elf32_Word nbuckets_gnu; /* Number of GNU hash buckets*/
210 Elf32_Word symndx_gnu; /* 1st accessible symbol on dynsym table */
211 Elf32_Word maskwords_bm_gnu; /* Bloom filter words - 1 (bitmask) */
212 Elf32_Word shift2_gnu; /* Bloom filter shift count */
213 Elf32_Word dynsymcount; /* Total entries in dynsym table */
214 const Elf_Addr *bloom_gnu; /* Bloom filter used by GNU hash func */
215 const Elf_Hashelt *buckets_gnu; /* GNU hash table bucket array */
216 const Elf_Hashelt *chain_zero_gnu; /* GNU hash table value array (Zeroed) */
218 const char *rpath; /* Search path specified in object */
219 const char *runpath; /* Search path with different priority */
220 Needed_Entry *needed; /* Shared objects needed by this one (%) */
221 Needed_Entry *needed_filtees;
222 Needed_Entry *needed_aux_filtees;
224 STAILQ_HEAD(, Struct_Name_Entry) names; /* List of names for this object we
226 Ver_Entry *vertab; /* Versions required /defined by this object */
227 int vernum; /* Number of entries in vertab */
229 Elf_Addr init; /* Initialization function to call */
230 Elf_Addr fini; /* Termination function to call */
231 Elf_Addr preinit_array; /* Pre-initialization array of functions */
232 Elf_Addr init_array; /* Initialization array of functions */
233 Elf_Addr fini_array; /* Termination array of functions */
234 int preinit_array_num; /* Number of entries in preinit_array */
235 int init_array_num; /* Number of entries in init_array */
236 int fini_array_num; /* Number of entries in fini_array */
238 int32_t osrel; /* OSREL note value */
239 uint32_t fctl0; /* FEATURE_CONTROL note desc[0] value */
241 bool mainprog : 1; /* True if this is the main program */
242 bool rtld : 1; /* True if this is the dynamic linker */
243 bool relocated : 1; /* True if processed by relocate_objects() */
244 bool ver_checked : 1; /* True if processed by rtld_verify_object_versions */
245 bool textrel : 1; /* True if there are relocations to text seg */
246 bool symbolic : 1; /* True if generated with "-Bsymbolic" */
247 bool bind_now : 1; /* True if all relocations should be made first */
248 bool traced : 1; /* Already printed in ldd trace output */
249 bool jmpslots_done : 1; /* Already have relocated the jump slots */
250 bool init_done : 1; /* Already have added object to init list */
251 bool tls_done : 1; /* Already allocated offset for static TLS */
252 bool phdr_alloc : 1; /* Phdr is allocated and needs to be freed. */
253 bool z_origin : 1; /* Process rpath and soname tokens */
254 bool z_nodelete : 1; /* Do not unload the object and dependencies */
255 bool z_noopen : 1; /* Do not load on dlopen */
256 bool z_loadfltr : 1; /* Immediately load filtees */
257 bool z_interpose : 1; /* Interpose all objects but main */
258 bool z_nodeflib : 1; /* Don't search default library path */
259 bool z_global : 1; /* Make the object global */
260 bool static_tls : 1; /* Needs static TLS allocation */
261 bool static_tls_copied : 1; /* Needs static TLS copying */
262 bool ref_nodel : 1; /* Refcount increased to prevent dlclose */
263 bool init_scanned: 1; /* Object is already on init list. */
264 bool on_fini_list: 1; /* Object is already on fini list. */
265 bool dag_inited : 1; /* Object has its DAG initialized. */
266 bool filtees_loaded : 1; /* Filtees loaded */
267 bool irelative : 1; /* Object has R_MACHDEP_IRELATIVE relocs */
268 bool gnu_ifunc : 1; /* Object has references to STT_GNU_IFUNC */
269 bool non_plt_gnu_ifunc : 1; /* Object has non-plt IFUNC references */
270 bool ifuncs_resolved : 1; /* Object ifuncs were already resolved */
271 bool crt_no_init : 1; /* Object' crt does not call _init/_fini */
272 bool valid_hash_sysv : 1; /* A valid System V hash hash tag is available */
273 bool valid_hash_gnu : 1; /* A valid GNU hash tag is available */
274 bool dlopened : 1; /* dlopen()-ed (vs. load statically) */
275 bool marker : 1; /* marker on the global obj list */
276 bool unholdfree : 1; /* unmap upon last unhold */
277 bool doomed : 1; /* Object cannot be referenced */
279 struct link_map linkmap; /* For GDB and dlinfo() */
280 Objlist dldags; /* Object belongs to these dlopened DAGs (%) */
281 Objlist dagmembers; /* DAG has these members (%) */
282 dev_t dev; /* Object's filesystem's device */
283 ino_t ino; /* Object's inode number */
284 void *priv; /* Platform-dependent */
287 #define RTLD_MAGIC 0xd550b87a
288 #define RTLD_VERSION 1
290 TAILQ_HEAD(obj_entry_q, Struct_Obj_Entry);
292 #define RTLD_STATIC_TLS_EXTRA 128
294 /* Flags to be passed into symlook_ family of functions. */
295 #define SYMLOOK_IN_PLT 0x01 /* Lookup for PLT symbol */
296 #define SYMLOOK_DLSYM 0x02 /* Return newest versioned symbol. Used by
298 #define SYMLOOK_EARLY 0x04 /* Symlook is done during initialization. */
299 #define SYMLOOK_IFUNC 0x08 /* Allow IFUNC processing in
302 /* Flags for load_object(). */
303 #define RTLD_LO_NOLOAD 0x01 /* dlopen() specified RTLD_NOLOAD. */
304 #define RTLD_LO_DLOPEN 0x02 /* Load_object() called from dlopen(). */
305 #define RTLD_LO_TRACE 0x04 /* Only tracing. */
306 #define RTLD_LO_NODELETE 0x08 /* Loaded object cannot be closed. */
307 #define RTLD_LO_FILTEES 0x10 /* Loading filtee. */
308 #define RTLD_LO_EARLY 0x20 /* Do not call ctors, postpone it to the
309 initialization during the image start. */
312 * Symbol cache entry used during relocation to avoid multiple lookups
313 * of the same symbol.
315 typedef struct Struct_SymCache {
316 const Elf_Sym *sym; /* Symbol table entry */
317 const Obj_Entry *obj; /* Shared object which defines it */
321 * This structure provides a reentrant way to keep a list of objects and
322 * check which ones have already been processed in some way.
324 typedef struct Struct_DoneList {
325 const Obj_Entry **objs; /* Array of object pointers */
326 unsigned int num_alloc; /* Allocated size of the array */
327 unsigned int num_used; /* Number of array slots used */
330 struct Struct_RtldLockState {
335 struct fill_search_info_args {
338 struct dl_serinfo *serinfo;
339 struct dl_serpath *serpath;
344 * The pack of arguments and results for the symbol lookup functions.
346 typedef struct Struct_SymLook {
350 const Ver_Entry *ventry;
352 const Obj_Entry *defobj_out;
353 const Elf_Sym *sym_out;
354 struct Struct_RtldLockState *lockstate;
357 void _rtld_error(const char *, ...) __printflike(1, 2) __exported;
358 void rtld_die(void) __dead2;
359 const char *rtld_strerror(int);
360 Obj_Entry *map_object(int, const char *, const struct stat *);
361 void *xcalloc(size_t, size_t);
362 void *xmalloc(size_t);
363 char *xstrdup(const char *);
364 void *malloc_aligned(size_t size, size_t align);
365 void free_aligned(void *ptr);
366 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
367 extern Elf_Sym sym_zero; /* For resolving undefined weak refs. */
368 extern bool ld_bind_not;
370 void dump_relocations(Obj_Entry *);
371 void dump_obj_relocations(Obj_Entry *);
372 void dump_Elf_Rel(Obj_Entry *, const Elf_Rel *, u_long);
373 void dump_Elf_Rela(Obj_Entry *, const Elf_Rela *, u_long);
376 * Function declarations.
378 unsigned long elf_hash(const char *);
379 const Elf_Sym *find_symdef(unsigned long, const Obj_Entry *,
380 const Obj_Entry **, int, SymCache *, struct Struct_RtldLockState *);
381 void lockdflt_init(void);
382 void digest_notes(Obj_Entry *, Elf_Addr, Elf_Addr);
383 Obj_Entry *globallist_curr(const Obj_Entry *obj);
384 Obj_Entry *globallist_next(const Obj_Entry *obj);
385 void obj_free(Obj_Entry *);
386 Obj_Entry *obj_new(void);
387 void _rtld_bind_start(void);
388 void *rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def);
389 void symlook_init(SymLook *, const char *);
390 int symlook_obj(SymLook *, const Obj_Entry *);
391 void *tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset);
392 void *allocate_tls(Obj_Entry *, void *, size_t, size_t);
393 void free_tls(void *, size_t, size_t);
394 void *allocate_module_tls(int index);
395 bool allocate_tls_offset(Obj_Entry *obj);
396 void free_tls_offset(Obj_Entry *obj);
397 const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long);
398 int convert_prot(int elfflags);
401 * MD function declarations.
403 int do_copy_relocations(Obj_Entry *);
404 int reloc_non_plt(Obj_Entry *, Obj_Entry *, int flags,
405 struct Struct_RtldLockState *);
406 int reloc_plt(Obj_Entry *, int flags, struct Struct_RtldLockState *);
407 int reloc_jmpslots(Obj_Entry *, int flags, struct Struct_RtldLockState *);
408 int reloc_iresolve(Obj_Entry *, struct Struct_RtldLockState *);
409 int reloc_gnu_ifunc(Obj_Entry *, int flags, struct Struct_RtldLockState *);
410 void ifunc_init(Elf_Auxinfo[__min_size(AT_COUNT)]);
412 void init_pltgot(Obj_Entry *);
413 void allocate_initial_tls(Obj_Entry *);
415 void *__crt_calloc(size_t num, size_t size);
416 void __crt_free(void *cp);
417 void *__crt_malloc(size_t nbytes);
418 void *__crt_realloc(void *cp, size_t nbytes);