xref: /freebsd/libexec/rtld-elf/rtld.h (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
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.
15  *
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.
26  */
27 
28 #ifndef RTLD_H /* { */
29 #define RTLD_H 1
30 
31 #include <machine/elf.h>
32 #include <sys/types.h>
33 #include <sys/queue.h>
34 
35 #include <elf-hints.h>
36 #include <link.h>
37 #include <stdarg.h>
38 #include <stdbool.h>
39 #include <setjmp.h>
40 #include <stddef.h>
41 
42 #include "rtld_lock.h"
43 #include "rtld_machdep.h"
44 
45 #define NEW(type)	((type *) xmalloc(sizeof(type)))
46 #define CNEW(type)	((type *) xcalloc(1, sizeof(type)))
47 
48 extern size_t tls_last_offset;
49 extern size_t tls_last_size;
50 extern size_t tls_static_space;
51 extern Elf_Addr tls_dtv_generation;
52 extern int tls_max_index;
53 extern size_t ld_static_tls_extra;
54 
55 extern int npagesizes;
56 extern size_t *pagesizes;
57 extern size_t page_size;
58 
59 extern int main_argc;
60 extern char **main_argv;
61 extern char **environ;
62 
63 struct stat;
64 struct Struct_Obj_Entry;
65 
66 /* Lists of shared objects */
67 typedef struct Struct_Objlist_Entry {
68     STAILQ_ENTRY(Struct_Objlist_Entry) link;
69     struct Struct_Obj_Entry *obj;
70 } Objlist_Entry;
71 
72 typedef STAILQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
73 
74 /* Types of init and fini functions */
75 typedef void (*InitFunc)(void);
76 typedef void (*InitArrFunc)(int, char **, char **);
77 
78 /* Lists of shared object dependencies */
79 typedef struct Struct_Needed_Entry {
80     struct Struct_Needed_Entry *next;
81     struct Struct_Obj_Entry *obj;
82     unsigned long name;		/* Offset of name in string table */
83 } Needed_Entry;
84 
85 typedef struct Struct_Name_Entry {
86     STAILQ_ENTRY(Struct_Name_Entry) link;
87     char   name[1];
88 } Name_Entry;
89 
90 /* Lock object */
91 typedef struct Struct_LockInfo {
92     void *context;		/* Client context for creating locks */
93     void *thelock;		/* The one big lock */
94     /* Debugging aids. */
95     volatile int rcount;	/* Number of readers holding lock */
96     volatile int wcount;	/* Number of writers holding lock */
97     /* Methods */
98     void *(*lock_create)(void *context);
99     void (*rlock_acquire)(void *lock);
100     void (*wlock_acquire)(void *lock);
101     void (*rlock_release)(void *lock);
102     void (*wlock_release)(void *lock);
103     void (*lock_destroy)(void *lock);
104     void (*context_destroy)(void *context);
105 } LockInfo;
106 
107 typedef struct Struct_Ver_Entry {
108 	Elf_Word     hash;
109 	unsigned int flags;
110 	const char  *name;
111 	const char  *file;
112 } Ver_Entry;
113 
114 typedef struct Struct_Sym_Match_Result {
115     const Elf_Sym *sym_out;
116     const Elf_Sym *vsymp;
117     int vcount;
118 } Sym_Match_Result;
119 
120 #define VER_INFO_HIDDEN	0x01
121 
122 /*
123  * Shared object descriptor.
124  *
125  * Items marked with "(%)" are dynamically allocated, and must be freed
126  * when the structure is destroyed.
127  *
128  * CAUTION: It appears that the JDK port peeks into these structures.
129  * It looks at "next" and "mapbase" at least.  Don't add new members
130  * near the front, until this can be straightened out.
131  */
132 typedef struct Struct_Obj_Entry {
133     /*
134      * These two items have to be set right for compatibility with the
135      * original ElfKit crt1.o.
136      */
137     Elf_Size magic;		/* Magic number (sanity check) */
138     Elf_Size version;		/* Version number of struct format */
139 
140     TAILQ_ENTRY(Struct_Obj_Entry) next;
141     char *path;			/* Pathname of underlying file (%) */
142     char *origin_path;		/* Directory path of origin file */
143     int refcount;		/* DAG references */
144     int holdcount;		/* Count of transient references */
145     int dl_refcount;		/* Number of times loaded by dlopen */
146 
147     /* These items are computed by map_object() or by digest_phdr(). */
148     caddr_t mapbase;		/* Base address of mapped region */
149     size_t mapsize;		/* Size of mapped region in bytes */
150     Elf_Addr vaddrbase;		/* Base address in shared object file */
151     caddr_t relocbase;		/* Relocation constant = mapbase - vaddrbase */
152     const Elf_Dyn *dynamic;	/* Dynamic section */
153     caddr_t entry;		/* Entry point */
154     const Elf_Phdr *phdr;	/* Program header if it is mapped, else NULL */
155     size_t phsize;		/* Size of program header in bytes */
156     const char *interp;		/* Pathname of the interpreter, if any */
157     Elf_Word stack_flags;
158 
159     /* TLS information */
160     int tlsindex;		/* Index in DTV for this module */
161     void *tlsinit;		/* Base address of TLS init block */
162     size_t tlsinitsize;		/* Size of TLS init block for this module */
163     size_t tlssize;		/* Size of TLS block for this module */
164     size_t tlsoffset;		/* Offset of static TLS block for this module */
165     size_t tlsalign;		/* Alignment of static TLS block */
166     size_t tlspoffset;		/* p_offset of the static TLS block */
167 
168     /* Items from the dynamic section. */
169     Elf_Addr *pltgot;		/* PLT or GOT, depending on architecture */
170     const Elf_Rel *rel;		/* Relocation entries */
171     unsigned long relsize;	/* Size in bytes of relocation info */
172     const Elf_Rela *rela;	/* Relocation entries with addend */
173     unsigned long relasize;	/* Size in bytes of addend relocation info */
174     const Elf_Relr *relr;	/* RELR relocation entries */
175     unsigned long relrsize;	/* Size in bytes of RELR relocations */
176     const Elf_Rel *pltrel;	/* PLT relocation entries */
177     unsigned long pltrelsize;	/* Size in bytes of PLT relocation info */
178     const Elf_Rela *pltrela;	/* PLT relocation entries with addend */
179     unsigned long pltrelasize;	/* Size in bytes of PLT addend reloc info */
180     const Elf_Sym *symtab;	/* Symbol table */
181     const char *strtab;		/* String table */
182     unsigned long strsize;	/* Size in bytes of string table */
183 
184     const Elf_Verneed *verneed; /* Required versions. */
185     Elf_Word verneednum;	/* Number of entries in verneed table */
186     const Elf_Verdef  *verdef;	/* Provided versions. */
187     Elf_Word verdefnum;		/* Number of entries in verdef table */
188     const Elf_Versym *versyms;  /* Symbol versions table */
189 
190     const Elf_Hashelt *buckets;	/* Hash table buckets array */
191     unsigned long nbuckets;	/* Number of buckets */
192     const Elf_Hashelt *chains;	/* Hash table chain array */
193     unsigned long nchains;	/* Number of entries in chain array */
194 
195     Elf32_Word nbuckets_gnu;		/* Number of GNU hash buckets*/
196     Elf32_Word symndx_gnu;		/* 1st accessible symbol on dynsym table */
197     Elf32_Word maskwords_bm_gnu;  	/* Bloom filter words - 1 (bitmask) */
198     Elf32_Word shift2_gnu;		/* Bloom filter shift count */
199     Elf32_Word dynsymcount;		/* Total entries in dynsym table */
200     const Elf_Addr *bloom_gnu;		/* Bloom filter used by GNU hash func */
201     const Elf_Hashelt *buckets_gnu;	/* GNU hash table bucket array */
202     const Elf_Hashelt *chain_zero_gnu;	/* GNU hash table value array (Zeroed) */
203 
204     const char *rpath;		/* Search path specified in object */
205     const char *runpath;	/* Search path with different priority */
206     Needed_Entry *needed;	/* Shared objects needed by this one (%) */
207     Needed_Entry *needed_filtees;
208     Needed_Entry *needed_aux_filtees;
209 
210     STAILQ_HEAD(, Struct_Name_Entry) names; /* List of names for this object we
211 					       know about. */
212     Ver_Entry *vertab;		/* Versions required /defined by this object */
213     int vernum;			/* Number of entries in vertab */
214 
215     Elf_Addr init;		/* Initialization function to call */
216     Elf_Addr fini;		/* Termination function to call */
217     Elf_Addr preinit_array;	/* Pre-initialization array of functions */
218     Elf_Addr init_array;	/* Initialization array of functions */
219     Elf_Addr fini_array;	/* Termination array of functions */
220     int preinit_array_num;	/* Number of entries in preinit_array */
221     int init_array_num; 	/* Number of entries in init_array */
222     int fini_array_num; 	/* Number of entries in fini_array */
223 
224     int32_t osrel;		/* OSREL note value */
225     uint32_t fctl0;		/* FEATURE_CONTROL note desc[0] value */
226 
227     bool mainprog : 1;		/* True if this is the main program */
228     bool rtld : 1;		/* True if this is the dynamic linker */
229     bool relocated : 1;		/* True if processed by relocate_objects() */
230     bool ver_checked : 1;	/* True if processed by rtld_verify_object_versions */
231     bool textrel : 1;		/* True if there are relocations to text seg */
232     bool symbolic : 1;		/* True if generated with "-Bsymbolic" */
233     bool deepbind : 1;		/* True if loaded with RTLD_DEEPBIND" */
234     bool bind_now : 1;		/* True if all relocations should be made first */
235     bool traced : 1;		/* Already printed in ldd trace output */
236     bool jmpslots_done : 1;	/* Already have relocated the jump slots */
237     bool init_done : 1;		/* Already have added object to init list */
238     bool tls_static : 1;	/* Already allocated offset for static TLS */
239     bool tls_dynamic : 1;	/* A non-static DTV entry has been allocated */
240     bool phdr_alloc : 1;	/* Phdr is allocated and needs to be freed. */
241     bool z_origin : 1;		/* Process rpath and soname tokens */
242     bool z_nodelete : 1;	/* Do not unload the object and dependencies */
243     bool z_noopen : 1;		/* Do not load on dlopen */
244     bool z_loadfltr : 1;	/* Immediately load filtees */
245     bool z_interpose : 1;	/* Interpose all objects but main */
246     bool z_nodeflib : 1;	/* Don't search default library path */
247     bool z_global : 1;		/* Make the object global */
248     bool z_pie : 1;		/* Object proclaimed itself PIE executable */
249     bool static_tls : 1;	/* Needs static TLS allocation */
250     bool static_tls_copied : 1;	/* Needs static TLS copying */
251     bool ref_nodel : 1;		/* Refcount increased to prevent dlclose */
252     bool init_scanned: 1;	/* Object is already on init list. */
253     bool on_fini_list: 1;	/* Object is already on fini list. */
254     bool dag_inited : 1;	/* Object has its DAG initialized. */
255     bool filtees_loaded : 1;	/* Filtees loaded */
256     bool filtees_loading : 1;	/* In process of filtees loading */
257     bool irelative : 1;		/* Object has R_MACHDEP_IRELATIVE relocs */
258     bool irelative_nonplt : 1;	/* Object has R_MACHDEP_IRELATIVE non-plt relocs */
259     bool gnu_ifunc : 1;		/* Object has references to STT_GNU_IFUNC */
260     bool non_plt_gnu_ifunc : 1;	/* Object has non-plt IFUNC references */
261     bool ifuncs_resolved : 1;	/* Object ifuncs were already resolved */
262     bool crt_no_init : 1;	/* Object' crt does not call _init/_fini */
263     bool valid_hash_sysv : 1;	/* A valid System V hash hash tag is available */
264     bool valid_hash_gnu : 1;	/* A valid GNU hash tag is available */
265     bool dlopened : 1;		/* dlopen()-ed (vs. load statically) */
266     bool marker : 1;		/* marker on the global obj list */
267     bool unholdfree : 1;	/* unmap upon last unhold */
268     bool doomed : 1;		/* Object cannot be referenced */
269 
270     MD_OBJ_ENTRY;
271 
272     struct link_map linkmap;	/* For GDB and dlinfo() */
273     Objlist dldags;		/* Object belongs to these dlopened DAGs (%) */
274     Objlist dagmembers;		/* DAG has these members (%) */
275     dev_t dev;			/* Object's filesystem's device */
276     ino_t ino;			/* Object's inode number */
277     void *priv;			/* Platform-dependent */
278 } Obj_Entry;
279 
280 #define RTLD_MAGIC	0xd550b87a
281 #define RTLD_VERSION	1
282 
283 TAILQ_HEAD(obj_entry_q, Struct_Obj_Entry);
284 
285 #define RTLD_STATIC_TLS_EXTRA	128
286 
287 /* Flags to be passed into symlook_ family of functions. */
288 #define SYMLOOK_IN_PLT	0x01	/* Lookup for PLT symbol */
289 #define SYMLOOK_DLSYM	0x02	/* Return newest versioned symbol. Used by
290 				   dlsym. */
291 #define	SYMLOOK_EARLY	0x04	/* Symlook is done during initialization. */
292 #define	SYMLOOK_IFUNC	0x08	/* Allow IFUNC processing in
293 				   reloc_non_plt(). */
294 
295 /* Flags for load_object(). */
296 #define	RTLD_LO_NOLOAD	0x01	/* dlopen() specified RTLD_NOLOAD. */
297 #define	RTLD_LO_DLOPEN	0x02	/* Load_object() called from dlopen(). */
298 #define	RTLD_LO_TRACE	0x04	/* Only tracing. */
299 #define	RTLD_LO_NODELETE 0x08	/* Loaded object cannot be closed. */
300 #define	RTLD_LO_FILTEES 0x10	/* Loading filtee. */
301 #define	RTLD_LO_EARLY	0x20	/* Do not call ctors, postpone it to the
302 				   initialization during the image start. */
303 #define	RTLD_LO_IGNSTLS 0x40	/* Do not allocate static TLS */
304 #define	RTLD_LO_DEEPBIND 0x80	/* Force symbolic for this object */
305 
306 /*
307  * Symbol cache entry used during relocation to avoid multiple lookups
308  * of the same symbol.
309  */
310 typedef struct Struct_SymCache {
311     const Elf_Sym *sym;		/* Symbol table entry */
312     const Obj_Entry *obj;	/* Shared object which defines it */
313 } SymCache;
314 
315 /*
316  * This structure provides a reentrant way to keep a list of objects and
317  * check which ones have already been processed in some way.
318  */
319 typedef struct Struct_DoneList {
320     const Obj_Entry **objs;		/* Array of object pointers */
321     unsigned int num_alloc;		/* Allocated size of the array */
322     unsigned int num_used;		/* Number of array slots used */
323 } DoneList;
324 
325 struct Struct_RtldLockState {
326 	int lockstate;
327 	sigjmp_buf env;
328 };
329 
330 struct fill_search_info_args {
331 	int request;
332 	unsigned int flags;
333 	struct dl_serinfo *serinfo;
334 	struct dl_serpath *serpath;
335 	char *strspace;
336 };
337 
338 /*
339  * The pack of arguments and results for the symbol lookup functions.
340  */
341 typedef struct Struct_SymLook {
342     const char *name;
343     unsigned long hash;
344     uint32_t hash_gnu;
345     const Ver_Entry *ventry;
346     int flags;
347     const Obj_Entry *defobj_out;
348     const Elf_Sym *sym_out;
349     struct Struct_RtldLockState *lockstate;
350 } SymLook;
351 
352 enum {
353 	LD_BIND_NOW = 0,
354 	LD_PRELOAD,
355 	LD_LIBMAP,
356 	LD_LIBRARY_PATH,
357 	LD_LIBRARY_PATH_FDS,
358 	LD_LIBMAP_DISABLE,
359 	LD_BIND_NOT,
360 	LD_DEBUG,
361 	LD_ELF_HINTS_PATH,
362 	LD_LOADFLTR,
363 	LD_LIBRARY_PATH_RPATH,
364 	LD_PRELOAD_FDS,
365 	LD_DYNAMIC_WEAK,
366 	LD_TRACE_LOADED_OBJECTS,
367 	LD_UTRACE,
368 	LD_DUMP_REL_PRE,
369 	LD_DUMP_REL_POST,
370 	LD_TRACE_LOADED_OBJECTS_PROGNAME,
371 	LD_TRACE_LOADED_OBJECTS_FMT1,
372 	LD_TRACE_LOADED_OBJECTS_FMT2,
373 	LD_TRACE_LOADED_OBJECTS_ALL,
374 	LD_SHOW_AUXV,
375 	LD_STATIC_TLS_EXTRA,
376 	LD_NO_DL_ITERATE_PHDR_AFTER_FORK,
377 };
378 
379 void _rtld_error(const char *, ...) __printflike(1, 2) __exported;
380 void rtld_die(void) __dead2;
381 const char *rtld_strerror(int);
382 Obj_Entry *map_object(int, const char *, const struct stat *);
383 void *xcalloc(size_t, size_t);
384 void *xmalloc(size_t);
385 char *xstrdup(const char *);
386 void *xmalloc_aligned(size_t size, size_t align, size_t offset);
387 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
388 extern Elf_Sym sym_zero;	/* For resolving undefined weak refs. */
389 extern bool ld_bind_not;
390 extern bool ld_fast_sigblock;
391 
392 void dump_relocations(Obj_Entry *);
393 void dump_obj_relocations(Obj_Entry *);
394 void dump_Elf_Rel(Obj_Entry *, const Elf_Rel *, u_long);
395 void dump_Elf_Rela(Obj_Entry *, const Elf_Rela *, u_long);
396 
397 /*
398  * Function declarations.
399  */
400 const char *ld_get_env_var(int idx);
401 uintptr_t rtld_round_page(uintptr_t);
402 uintptr_t rtld_trunc_page(uintptr_t);
403 Elf32_Word elf_hash(const char *);
404 const Elf_Sym *find_symdef(unsigned long, const Obj_Entry *,
405   const Obj_Entry **, int, SymCache *, struct Struct_RtldLockState *);
406 void lockdflt_init(void);
407 void digest_notes(Obj_Entry *, Elf_Addr, Elf_Addr);
408 Obj_Entry *globallist_curr(const Obj_Entry *obj);
409 Obj_Entry *globallist_next(const Obj_Entry *obj);
410 void obj_free(Obj_Entry *);
411 Obj_Entry *obj_new(void);
412 Obj_Entry *obj_from_addr(const void *);
413 void _rtld_bind_start(void);
414 void *rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def);
415 void symlook_init(SymLook *, const char *);
416 int symlook_obj(SymLook *, const Obj_Entry *);
417 void *tls_get_addr_common(uintptr_t **dtvp, int index, size_t offset);
418 void *allocate_tls(Obj_Entry *, void *, size_t, size_t);
419 void free_tls(void *, size_t, size_t);
420 void *allocate_module_tls(int index);
421 bool allocate_tls_offset(Obj_Entry *obj);
422 void free_tls_offset(Obj_Entry *obj);
423 const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long);
424 int convert_prot(int elfflags);
425 bool check_elf_headers(const Elf_Ehdr *hdr, const char *path);
426 
427 /*
428  * MD function declarations.
429  */
430 int do_copy_relocations(Obj_Entry *);
431 int reloc_non_plt(Obj_Entry *, Obj_Entry *, int flags,
432     struct Struct_RtldLockState *);
433 int reloc_plt(Obj_Entry *, int flags, struct Struct_RtldLockState *);
434 int reloc_jmpslots(Obj_Entry *, int flags, struct Struct_RtldLockState *);
435 int reloc_iresolve(Obj_Entry *, struct Struct_RtldLockState *);
436 int reloc_iresolve_nonplt(Obj_Entry *, struct Struct_RtldLockState *);
437 int reloc_gnu_ifunc(Obj_Entry *, int flags, struct Struct_RtldLockState *);
438 void ifunc_init(Elf_Auxinfo *[__min_size(AT_COUNT)]);
439 void init_pltgot(Obj_Entry *);
440 void allocate_initial_tls(Obj_Entry *);
441 
442 #endif /* } */
443