xref: /dragonfly/libexec/rtld-elf/rtld.h (revision 31524921)
1 /*-
2  * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
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.
13  *
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.
24  *
25  * $FreeBSD$
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 #ifndef STANDARD_LIBRARY_PATH
46 #define STANDARD_LIBRARY_PATH	"/lib:/usr/lib"
47 #endif
48 
49 #define NEW(type)	((type *) xmalloc(sizeof(type)))
50 #define CNEW(type)	((type *) xcalloc(1, sizeof(type)))
51 
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;
57 
58 extern int main_argc;
59 extern char **main_argv;
60 extern char **environ;
61 extern const char *__ld_sharedlib_base;
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     struct Struct_Obj_Entry *next;
141     char *path;			/* Pathname of underlying file (%) */
142     char *origin_path;		/* Directory path of origin file */
143     int refcount;
144     int dl_refcount;		/* Number of times loaded by dlopen */
145 
146     /* These items are computed by map_object() or by digest_phdr(). */
147     caddr_t mapbase;		/* Base address of mapped region */
148     size_t mapsize;		/* Size of mapped region in bytes */
149     size_t textsize;		/* Size of text segment 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 
167     caddr_t relro_page; 	/* Address of first page of read-only data */
168     size_t relro_size;  	/* Size of relro page(s) in bytes */
169 
170     /* Items from the dynamic section. */
171     Elf_Addr *pltgot;		/* PLT or GOT, depending on architecture */
172     const Elf_Rel *rel;		/* Relocation entries */
173     unsigned long relsize;	/* Size in bytes of relocation info */
174     const Elf_Rela *rela;	/* Relocation entries with addend */
175     unsigned long relasize;	/* Size in bytes of addend relocation info */
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     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     char *rpath;		/* Search path specified in object */
205     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 
226     bool mainprog : 1;		/* True if this is the main program */
227     bool rtld : 1;		/* True if this is the dynamic linker */
228     bool relocated : 1;		/* True if processed by relocate_objects() */
229     bool ver_checked : 1;	/* True if processed by rtld_verify_object_versions */
230     bool textrel : 1;		/* True if there are relocations to text seg */
231     bool symbolic : 1;		/* True if generated with "-Bsymbolic" */
232     bool bind_now : 1;		/* True if all relocations should be made first */
233     bool traced : 1;		/* Already printed in ldd trace output */
234     bool jmpslots_done : 1;	/* Already have relocated the jump slots */
235     bool init_done : 1;		/* Already have added object to init list */
236     bool tls_done : 1;		/* Already allocated offset for static TLS */
237     bool phdr_alloc : 1;	/* Phdr is allocated and needs to be freed. */
238     bool z_origin : 1;		/* Process rpath and soname tokens */
239     bool z_nodelete : 1;	/* Do not unload the object and dependencies */
240     bool z_noopen : 1;		/* Do not load on dlopen */
241     bool z_loadfltr : 1;	/* Immediately load filtees */
242     bool z_interpose : 1;	/* Interpose all objects but main */
243     bool z_nodeflib : 1;	/* Don't search default library path */
244     bool ref_nodel : 1;		/* Refcount increased to prevent dlclose */
245     bool init_scanned: 1;	/* Object is already on init list. */
246     bool on_fini_list: 1;	/* Object is already on fini list. */
247     bool dag_inited : 1;	/* Object has its DAG initialized. */
248     bool filtees_loaded : 1;	/* Filtees loaded */
249     bool irelative : 1;		/* Object has R_MACHDEP_IRELATIVE relocs */
250     bool gnu_ifunc : 1;		/* Object has references to STT_GNU_IFUNC */
251     bool non_plt_gnu_ifunc : 1;	/* Object has non-plt IFUNC references */
252     bool crt_no_init : 1;	/* Object's crt does not call _init/_fini */
253     bool note_present : 1;	/* True if at least one PT_NOTE header found */
254     bool valid_hash_sysv : 1;	/* A valid System V hash hash tag is available */
255     bool valid_hash_gnu : 1;	/* A valid GNU hash tag is available */
256 
257     struct link_map linkmap;	/* For GDB and dlinfo() */
258     Objlist dldags;		/* Object belongs to these dlopened DAGs (%) */
259     Objlist dagmembers;		/* DAG has these members (%) */
260     dev_t dev;			/* Object's filesystem's device */
261     ino_t ino;			/* Object's inode number */
262     void *priv;			/* Platform-dependent */
263 } Obj_Entry;
264 
265 #define RTLD_MAGIC	0xd550b87a
266 #define RTLD_VERSION	1
267 
268 #define RTLD_FUNCTRACE "_rtld_functrace"
269 
270 /* Flags to be passed into symlook_ family of functions. */
271 #define SYMLOOK_IN_PLT	0x01	/* Lookup for PLT symbol */
272 #define SYMLOOK_DLSYM	0x02	/* Return newest versioned symbol. Used by
273 				   dlsym. */
274 #define	SYMLOOK_EARLY	0x04	/* Symlook is done during initialization. */
275 #define	SYMLOOK_IFUNC	0x08	/* Allow IFUNC processing in
276 				   reloc_non_plt(). */
277 
278 /* Flags for load_object(). */
279 #define	RTLD_LO_NOLOAD	0x01	/* dlopen() specified RTLD_NOLOAD. */
280 #define	RTLD_LO_DLOPEN	0x02	/* Load_object() called from dlopen(). */
281 #define	RTLD_LO_TRACE	0x04	/* Only tracing. */
282 #define	RTLD_LO_NODELETE 0x08	/* Loaded object cannot be closed. */
283 #define	RTLD_LO_FILTEES 0x10	/* Loading filtee. */
284 #define	RTLD_LO_EARLY	0x20	/* Do not call ctors, postpone it to the
285 				   initialization during the image start. */
286 
287 /*
288  * Symbol cache entry used during relocation to avoid multiple lookups
289  * of the same symbol.
290  */
291 typedef struct Struct_SymCache {
292     const Elf_Sym *sym;		/* Symbol table entry */
293     const Obj_Entry *obj;	/* Shared object which defines it */
294 } SymCache;
295 
296 /*
297  * This structure provides a reentrant way to keep a list of objects and
298  * check which ones have already been processed in some way.
299  */
300 typedef struct Struct_DoneList {
301     const Obj_Entry **objs;		/* Array of object pointers */
302     unsigned int num_alloc;		/* Allocated size of the array */
303     unsigned int num_used;		/* Number of array slots used */
304 } DoneList;
305 
306 struct Struct_RtldLockState {
307 	int lockstate;
308 	sigjmp_buf env;
309 };
310 
311 struct fill_search_info_args {
312 	int request;
313 	unsigned int flags;
314 	struct dl_serinfo *serinfo;
315 	struct dl_serpath *serpath;
316 	char *strspace;
317 };
318 
319 /*
320  * The pack of arguments and results for the symbol lookup functions.
321  */
322 typedef struct Struct_SymLook {
323     const char *name;
324     unsigned long hash;
325     uint_fast32_t hash_gnu;
326     const Ver_Entry *ventry;
327     int flags;
328     const Obj_Entry *defobj_out;
329     const Elf_Sym *sym_out;
330     struct Struct_RtldLockState *lockstate;
331 } SymLook;
332 
333 void _rtld_error(const char *, ...) __printflike(1, 2);
334 const char *rtld_strerror(int);
335 Obj_Entry *map_object(int, const char *, const struct stat *);
336 void *xcalloc(size_t, size_t);
337 void *xmalloc(size_t);
338 char *xstrdup(const char *);
339 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
340 
341 void dump_relocations(Obj_Entry *);
342 void dump_obj_relocations(Obj_Entry *);
343 void dump_Elf_Rel(Obj_Entry *, const Elf_Rel *, u_long);
344 void dump_Elf_Rela(Obj_Entry *, const Elf_Rela *, u_long);
345 
346 /*
347  * Function declarations.
348  */
349 const char *basename(const char *);
350 unsigned long elf_hash(const char *);
351 const Elf_Sym *find_symdef(unsigned long, const Obj_Entry *,
352   const Obj_Entry **, int, SymCache *, struct Struct_RtldLockState *);
353 void init_pltgot(Obj_Entry *);
354 void lockdflt_init(void);
355 void digest_notes(Obj_Entry *, Elf_Addr, Elf_Addr);
356 void obj_free(Obj_Entry *);
357 Obj_Entry *obj_new(void);
358 void _rtld_bind_start(void);
359 void *rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def);
360 void symlook_init(SymLook *, const char *);
361 int symlook_obj(SymLook *, const Obj_Entry *);
362 void *tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset);
363 struct tls_tcb	*allocate_tls(Obj_Entry *);
364 void free_tls(struct tls_tcb *);
365 void *allocate_module_tls(int index);
366 bool allocate_tls_offset(Obj_Entry *obj);
367 void free_tls_offset(Obj_Entry *obj);
368 const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long);
369 
370 /*
371  * MD function declarations.
372  */
373 int do_copy_relocations(Obj_Entry *);
374 int reloc_non_plt(Obj_Entry *, Obj_Entry *, int flags,
375     struct Struct_RtldLockState *);
376 int reloc_plt(Obj_Entry *);
377 int reloc_jmpslots(Obj_Entry *, int flags, struct Struct_RtldLockState *);
378 int reloc_iresolve(Obj_Entry *, struct Struct_RtldLockState *);
379 int reloc_gnu_ifunc(Obj_Entry *, int flags, struct Struct_RtldLockState *);
380 void allocate_initial_tls(Obj_Entry *);
381 
382 #endif /* } */
383