xref: /freebsd/libexec/rtld-elf/rtld.h (revision 5ab1c5846ff41be24b1f6beb0317bf8258cd4409)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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  * $FreeBSD$
28  */
29 
30 #ifndef RTLD_H /* { */
31 #define RTLD_H 1
32 
33 #include <machine/elf.h>
34 #include <sys/types.h>
35 #include <sys/queue.h>
36 
37 #include <elf-hints.h>
38 #include <link.h>
39 #include <stdarg.h>
40 #include <setjmp.h>
41 #include <stddef.h>
42 
43 #include "rtld_lock.h"
44 #include "rtld_machdep.h"
45 
46 #define NEW(type)	((type *) xmalloc(sizeof(type)))
47 #define CNEW(type)	((type *) xcalloc(1, sizeof(type)))
48 
49 /* We might as well do booleans like C++. */
50 typedef unsigned char bool;
51 #define false	0
52 #define true	1
53 
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;
59 
60 extern int npagesizes;
61 extern size_t *pagesizes;
62 
63 extern int main_argc;
64 extern char **main_argv;
65 extern char **environ;
66 
67 struct stat;
68 struct Struct_Obj_Entry;
69 
70 /* Lists of shared objects */
71 typedef struct Struct_Objlist_Entry {
72     STAILQ_ENTRY(Struct_Objlist_Entry) link;
73     struct Struct_Obj_Entry *obj;
74 } Objlist_Entry;
75 
76 typedef STAILQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
77 
78 /* Types of init and fini functions */
79 typedef void (*InitFunc)(void);
80 typedef void (*InitArrFunc)(int, char **, char **);
81 
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 */
87 } Needed_Entry;
88 
89 typedef struct Struct_Name_Entry {
90     STAILQ_ENTRY(Struct_Name_Entry) link;
91     char   name[1];
92 } Name_Entry;
93 
94 /* Lock object */
95 typedef struct Struct_LockInfo {
96     void *context;		/* Client context for creating locks */
97     void *thelock;		/* The one big lock */
98     /* Debugging aids. */
99     volatile int rcount;	/* Number of readers holding lock */
100     volatile int wcount;	/* Number of writers holding lock */
101     /* Methods */
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);
109 } LockInfo;
110 
111 typedef struct Struct_Ver_Entry {
112 	Elf_Word     hash;
113 	unsigned int flags;
114 	const char  *name;
115 	const char  *file;
116 } Ver_Entry;
117 
118 typedef struct Struct_Sym_Match_Result {
119     const Elf_Sym *sym_out;
120     const Elf_Sym *vsymp;
121     int vcount;
122 } Sym_Match_Result;
123 
124 #define VER_INFO_HIDDEN	0x01
125 
126 /*
127  * Shared object descriptor.
128  *
129  * Items marked with "(%)" are dynamically allocated, and must be freed
130  * when the structure is destroyed.
131  *
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.
135  */
136 typedef struct Struct_Obj_Entry {
137     /*
138      * These two items have to be set right for compatibility with the
139      * original ElfKit crt1.o.
140      */
141     Elf_Size magic;		/* Magic number (sanity check) */
142     Elf_Size version;		/* Version number of struct format */
143 
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 */
150 
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     Elf_Addr vaddrbase;		/* Base address in shared object file */
155     caddr_t relocbase;		/* Relocation constant = mapbase - vaddrbase */
156     const Elf_Dyn *dynamic;	/* Dynamic section */
157     caddr_t entry;		/* Entry point */
158     const Elf_Phdr *phdr;	/* Program header if it is mapped, else NULL */
159     size_t phsize;		/* Size of program header in bytes */
160     const char *interp;		/* Pathname of the interpreter, if any */
161     Elf_Word stack_flags;
162 
163     /* TLS information */
164     int tlsindex;		/* Index in DTV for this module */
165     void *tlsinit;		/* Base address of TLS init block */
166     size_t tlsinitsize;		/* Size of TLS init block for this module */
167     size_t tlssize;		/* Size of TLS block for this module */
168     size_t tlsoffset;		/* Offset of static TLS block for this module */
169     size_t tlsalign;		/* Alignment of static TLS block */
170 
171     caddr_t relro_page;
172     size_t relro_size;
173 
174     /* Items from the dynamic section. */
175     Elf_Addr *pltgot;		/* PLT or GOT, depending on architecture */
176     const Elf_Rel *rel;		/* Relocation entries */
177     unsigned long relsize;	/* Size in bytes of relocation info */
178     const Elf_Rela *rela;	/* Relocation entries with addend */
179     unsigned long relasize;	/* Size in bytes of addend relocation info */
180     const Elf_Rel *pltrel;	/* PLT relocation entries */
181     unsigned long pltrelsize;	/* Size in bytes of PLT relocation info */
182     const Elf_Rela *pltrela;	/* PLT relocation entries with addend */
183     unsigned long pltrelasize;	/* Size in bytes of PLT addend reloc info */
184     const Elf_Sym *symtab;	/* Symbol table */
185     const char *strtab;		/* String table */
186     unsigned long strsize;	/* Size in bytes of string table */
187 #ifdef __mips__
188     Elf_Word local_gotno;	/* Number of local GOT entries */
189     Elf_Word symtabno;		/* Number of dynamic symbols */
190     Elf_Word gotsym;		/* First dynamic symbol in GOT */
191     Elf_Addr *mips_pltgot;	/* Second PLT GOT */
192 #endif
193 #ifdef __powerpc__
194 #ifdef __powerpc64__
195     Elf_Addr glink;		/* GLINK PLT call stub section */
196 #else
197     Elf_Addr *gotptr;		/* GOT pointer (secure-plt only) */
198 #endif
199 #endif
200 
201     const Elf_Verneed *verneed; /* Required versions. */
202     Elf_Word verneednum;	/* Number of entries in verneed table */
203     const Elf_Verdef  *verdef;	/* Provided versions. */
204     Elf_Word verdefnum;		/* Number of entries in verdef table */
205     const Elf_Versym *versyms;  /* Symbol versions table */
206 
207     const Elf_Hashelt *buckets;	/* Hash table buckets array */
208     unsigned long nbuckets;	/* Number of buckets */
209     const Elf_Hashelt *chains;	/* Hash table chain array */
210     unsigned long nchains;	/* Number of entries in chain array */
211 
212     Elf32_Word nbuckets_gnu;		/* Number of GNU hash buckets*/
213     Elf32_Word symndx_gnu;		/* 1st accessible symbol on dynsym table */
214     Elf32_Word maskwords_bm_gnu;  	/* Bloom filter words - 1 (bitmask) */
215     Elf32_Word shift2_gnu;		/* Bloom filter shift count */
216     Elf32_Word dynsymcount;		/* Total entries in dynsym table */
217     const Elf_Addr *bloom_gnu;		/* Bloom filter used by GNU hash func */
218     const Elf_Hashelt *buckets_gnu;	/* GNU hash table bucket array */
219     const Elf_Hashelt *chain_zero_gnu;	/* GNU hash table value array (Zeroed) */
220 
221     const char *rpath;		/* Search path specified in object */
222     const char *runpath;	/* Search path with different priority */
223     Needed_Entry *needed;	/* Shared objects needed by this one (%) */
224     Needed_Entry *needed_filtees;
225     Needed_Entry *needed_aux_filtees;
226 
227     STAILQ_HEAD(, Struct_Name_Entry) names; /* List of names for this object we
228 					       know about. */
229     Ver_Entry *vertab;		/* Versions required /defined by this object */
230     int vernum;			/* Number of entries in vertab */
231 
232     Elf_Addr init;		/* Initialization function to call */
233     Elf_Addr fini;		/* Termination function to call */
234     Elf_Addr preinit_array;	/* Pre-initialization array of functions */
235     Elf_Addr init_array;	/* Initialization array of functions */
236     Elf_Addr fini_array;	/* Termination array of functions */
237     int preinit_array_num;	/* Number of entries in preinit_array */
238     int init_array_num; 	/* Number of entries in init_array */
239     int fini_array_num; 	/* Number of entries in fini_array */
240 
241     int32_t osrel;		/* OSREL note value */
242     uint32_t fctl0;		/* FEATURE_CONTROL note desc[0] value */
243 
244     bool mainprog : 1;		/* True if this is the main program */
245     bool rtld : 1;		/* True if this is the dynamic linker */
246     bool relocated : 1;		/* True if processed by relocate_objects() */
247     bool ver_checked : 1;	/* True if processed by rtld_verify_object_versions */
248     bool textrel : 1;		/* True if there are relocations to text seg */
249     bool symbolic : 1;		/* True if generated with "-Bsymbolic" */
250     bool bind_now : 1;		/* True if all relocations should be made first */
251     bool traced : 1;		/* Already printed in ldd trace output */
252     bool jmpslots_done : 1;	/* Already have relocated the jump slots */
253     bool init_done : 1;		/* Already have added object to init list */
254     bool tls_done : 1;		/* Already allocated offset for static TLS */
255     bool phdr_alloc : 1;	/* Phdr is allocated and needs to be freed. */
256     bool z_origin : 1;		/* Process rpath and soname tokens */
257     bool z_nodelete : 1;	/* Do not unload the object and dependencies */
258     bool z_noopen : 1;		/* Do not load on dlopen */
259     bool z_loadfltr : 1;	/* Immediately load filtees */
260     bool z_interpose : 1;	/* Interpose all objects but main */
261     bool z_nodeflib : 1;	/* Don't search default library path */
262     bool z_global : 1;		/* Make the object global */
263     bool static_tls : 1;	/* Needs static TLS allocation */
264     bool static_tls_copied : 1;	/* Needs static TLS copying */
265     bool ref_nodel : 1;		/* Refcount increased to prevent dlclose */
266     bool init_scanned: 1;	/* Object is already on init list. */
267     bool on_fini_list: 1;	/* Object is already on fini list. */
268     bool dag_inited : 1;	/* Object has its DAG initialized. */
269     bool filtees_loaded : 1;	/* Filtees loaded */
270     bool irelative : 1;		/* Object has R_MACHDEP_IRELATIVE relocs */
271     bool gnu_ifunc : 1;		/* Object has references to STT_GNU_IFUNC */
272     bool non_plt_gnu_ifunc : 1;	/* Object has non-plt IFUNC references */
273     bool ifuncs_resolved : 1;	/* Object ifuncs were already resolved */
274     bool crt_no_init : 1;	/* Object' crt does not call _init/_fini */
275     bool valid_hash_sysv : 1;	/* A valid System V hash hash tag is available */
276     bool valid_hash_gnu : 1;	/* A valid GNU hash tag is available */
277     bool dlopened : 1;		/* dlopen()-ed (vs. load statically) */
278     bool marker : 1;		/* marker on the global obj list */
279     bool unholdfree : 1;	/* unmap upon last unhold */
280     bool doomed : 1;		/* Object cannot be referenced */
281 
282     struct link_map linkmap;	/* For GDB and dlinfo() */
283     Objlist dldags;		/* Object belongs to these dlopened DAGs (%) */
284     Objlist dagmembers;		/* DAG has these members (%) */
285     dev_t dev;			/* Object's filesystem's device */
286     ino_t ino;			/* Object's inode number */
287     void *priv;			/* Platform-dependent */
288 } Obj_Entry;
289 
290 #define RTLD_MAGIC	0xd550b87a
291 #define RTLD_VERSION	1
292 
293 TAILQ_HEAD(obj_entry_q, Struct_Obj_Entry);
294 
295 #define RTLD_STATIC_TLS_EXTRA	128
296 
297 /* Flags to be passed into symlook_ family of functions. */
298 #define SYMLOOK_IN_PLT	0x01	/* Lookup for PLT symbol */
299 #define SYMLOOK_DLSYM	0x02	/* Return newest versioned symbol. Used by
300 				   dlsym. */
301 #define	SYMLOOK_EARLY	0x04	/* Symlook is done during initialization. */
302 #define	SYMLOOK_IFUNC	0x08	/* Allow IFUNC processing in
303 				   reloc_non_plt(). */
304 
305 /* Flags for load_object(). */
306 #define	RTLD_LO_NOLOAD	0x01	/* dlopen() specified RTLD_NOLOAD. */
307 #define	RTLD_LO_DLOPEN	0x02	/* Load_object() called from dlopen(). */
308 #define	RTLD_LO_TRACE	0x04	/* Only tracing. */
309 #define	RTLD_LO_NODELETE 0x08	/* Loaded object cannot be closed. */
310 #define	RTLD_LO_FILTEES 0x10	/* Loading filtee. */
311 #define	RTLD_LO_EARLY	0x20	/* Do not call ctors, postpone it to the
312 				   initialization during the image start. */
313 
314 /*
315  * Symbol cache entry used during relocation to avoid multiple lookups
316  * of the same symbol.
317  */
318 typedef struct Struct_SymCache {
319     const Elf_Sym *sym;		/* Symbol table entry */
320     const Obj_Entry *obj;	/* Shared object which defines it */
321 } SymCache;
322 
323 /*
324  * This structure provides a reentrant way to keep a list of objects and
325  * check which ones have already been processed in some way.
326  */
327 typedef struct Struct_DoneList {
328     const Obj_Entry **objs;		/* Array of object pointers */
329     unsigned int num_alloc;		/* Allocated size of the array */
330     unsigned int num_used;		/* Number of array slots used */
331 } DoneList;
332 
333 struct Struct_RtldLockState {
334 	int lockstate;
335 	sigjmp_buf env;
336 };
337 
338 struct fill_search_info_args {
339 	int request;
340 	unsigned int flags;
341 	struct dl_serinfo *serinfo;
342 	struct dl_serpath *serpath;
343 	char *strspace;
344 };
345 
346 /*
347  * The pack of arguments and results for the symbol lookup functions.
348  */
349 typedef struct Struct_SymLook {
350     const char *name;
351     unsigned long hash;
352     uint32_t hash_gnu;
353     const Ver_Entry *ventry;
354     int flags;
355     const Obj_Entry *defobj_out;
356     const Elf_Sym *sym_out;
357     struct Struct_RtldLockState *lockstate;
358 } SymLook;
359 
360 void _rtld_error(const char *, ...) __printflike(1, 2) __exported;
361 void rtld_die(void) __dead2;
362 const char *rtld_strerror(int);
363 Obj_Entry *map_object(int, const char *, const struct stat *);
364 void *xcalloc(size_t, size_t);
365 void *xmalloc(size_t);
366 char *xstrdup(const char *);
367 void *malloc_aligned(size_t size, size_t align);
368 void free_aligned(void *ptr);
369 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
370 extern Elf_Sym sym_zero;	/* For resolving undefined weak refs. */
371 extern bool ld_bind_not;
372 
373 void dump_relocations(Obj_Entry *);
374 void dump_obj_relocations(Obj_Entry *);
375 void dump_Elf_Rel(Obj_Entry *, const Elf_Rel *, u_long);
376 void dump_Elf_Rela(Obj_Entry *, const Elf_Rela *, u_long);
377 
378 /*
379  * Function declarations.
380  */
381 unsigned long elf_hash(const char *);
382 const Elf_Sym *find_symdef(unsigned long, const Obj_Entry *,
383   const Obj_Entry **, int, SymCache *, struct Struct_RtldLockState *);
384 void lockdflt_init(void);
385 void digest_notes(Obj_Entry *, Elf_Addr, Elf_Addr);
386 Obj_Entry *globallist_curr(const Obj_Entry *obj);
387 Obj_Entry *globallist_next(const Obj_Entry *obj);
388 void obj_free(Obj_Entry *);
389 Obj_Entry *obj_new(void);
390 void _rtld_bind_start(void);
391 void *rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def);
392 void symlook_init(SymLook *, const char *);
393 int symlook_obj(SymLook *, const Obj_Entry *);
394 void *tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset);
395 void *allocate_tls(Obj_Entry *, void *, size_t, size_t);
396 void free_tls(void *, size_t, size_t);
397 void *allocate_module_tls(int index);
398 bool allocate_tls_offset(Obj_Entry *obj);
399 void free_tls_offset(Obj_Entry *obj);
400 const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long);
401 int convert_prot(int elfflags);
402 
403 /*
404  * MD function declarations.
405  */
406 int do_copy_relocations(Obj_Entry *);
407 int reloc_non_plt(Obj_Entry *, Obj_Entry *, int flags,
408     struct Struct_RtldLockState *);
409 int reloc_plt(Obj_Entry *, int flags, struct Struct_RtldLockState *);
410 int reloc_jmpslots(Obj_Entry *, int flags, struct Struct_RtldLockState *);
411 int reloc_iresolve(Obj_Entry *, struct Struct_RtldLockState *);
412 int reloc_gnu_ifunc(Obj_Entry *, int flags, struct Struct_RtldLockState *);
413 void ifunc_init(Elf_Auxinfo[__min_size(AT_COUNT)]);
414 void pre_init(void);
415 void init_pltgot(Obj_Entry *);
416 void allocate_initial_tls(Obj_Entry *);
417 
418 void *__crt_calloc(size_t num, size_t size);
419 void __crt_free(void *cp);
420 void *__crt_malloc(size_t nbytes);
421 void *__crt_realloc(void *cp, size_t nbytes);
422 
423 #endif /* } */
424