xref: /freebsd/libexec/rtld-elf/rtld.h (revision 6472ac3d8a86336899b6cfb789a4cd9897e3fab5)
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 <setjmp.h>
39 #include <stddef.h>
40 
41 #include "rtld_lock.h"
42 #include "rtld_machdep.h"
43 
44 #ifdef COMPAT_32BIT
45 #undef STANDARD_LIBRARY_PATH
46 #undef _PATH_ELF_HINTS
47 #define	_PATH_ELF_HINTS		"/var/run/ld-elf32.so.hints"
48 /* For running 32 bit binaries  */
49 #define	STANDARD_LIBRARY_PATH	"/lib32:/usr/lib32"
50 #define LD_ "LD_32_"
51 #endif
52 
53 #ifndef STANDARD_LIBRARY_PATH
54 #define STANDARD_LIBRARY_PATH	"/lib:/usr/lib"
55 #endif
56 #ifndef LD_
57 #define LD_ "LD_"
58 #endif
59 
60 #define NEW(type)	((type *) xmalloc(sizeof(type)))
61 #define CNEW(type)	((type *) xcalloc(sizeof(type)))
62 
63 /* We might as well do booleans like C++. */
64 typedef unsigned char bool;
65 #define false	0
66 #define true	1
67 
68 extern size_t tls_last_offset;
69 extern size_t tls_last_size;
70 extern size_t tls_static_space;
71 extern int tls_dtv_generation;
72 extern int tls_max_index;
73 
74 struct stat;
75 struct Struct_Obj_Entry;
76 
77 /* Lists of shared objects */
78 typedef struct Struct_Objlist_Entry {
79     STAILQ_ENTRY(Struct_Objlist_Entry) link;
80     struct Struct_Obj_Entry *obj;
81 } Objlist_Entry;
82 
83 typedef STAILQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
84 
85 /* Types of init and fini functions */
86 typedef void (*InitFunc)(void);
87 
88 /* Lists of shared object dependencies */
89 typedef struct Struct_Needed_Entry {
90     struct Struct_Needed_Entry *next;
91     struct Struct_Obj_Entry *obj;
92     unsigned long name;		/* Offset of name in string table */
93 } Needed_Entry;
94 
95 typedef struct Struct_Name_Entry {
96     STAILQ_ENTRY(Struct_Name_Entry) link;
97     char   name[1];
98 } Name_Entry;
99 
100 /* Lock object */
101 typedef struct Struct_LockInfo {
102     void *context;		/* Client context for creating locks */
103     void *thelock;		/* The one big lock */
104     /* Debugging aids. */
105     volatile int rcount;	/* Number of readers holding lock */
106     volatile int wcount;	/* Number of writers holding lock */
107     /* Methods */
108     void *(*lock_create)(void *context);
109     void (*rlock_acquire)(void *lock);
110     void (*wlock_acquire)(void *lock);
111     void (*rlock_release)(void *lock);
112     void (*wlock_release)(void *lock);
113     void (*lock_destroy)(void *lock);
114     void (*context_destroy)(void *context);
115 } LockInfo;
116 
117 typedef struct Struct_Ver_Entry {
118 	Elf_Word     hash;
119 	unsigned int flags;
120 	const char  *name;
121 	const char  *file;
122 } Ver_Entry;
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     struct Struct_Obj_Entry *next;
145     char *path;			/* Pathname of underlying file (%) */
146     char *origin_path;		/* Directory path of origin file */
147     int refcount;
148     int dl_refcount;		/* Number of times loaded by dlopen */
149 
150     /* These items are computed by map_object() or by digest_phdr(). */
151     caddr_t mapbase;		/* Base address of mapped region */
152     size_t mapsize;		/* Size of mapped region in bytes */
153     size_t textsize;		/* Size of text segment 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     /* Items from the dynamic section. */
172     Elf_Addr *pltgot;		/* PLT or GOT, depending on architecture */
173     const Elf_Rel *rel;		/* Relocation entries */
174     unsigned long relsize;	/* Size in bytes of relocation info */
175     const Elf_Rela *rela;	/* Relocation entries with addend */
176     unsigned long relasize;	/* Size in bytes of addend relocation info */
177     const Elf_Rel *pltrel;	/* PLT relocation entries */
178     unsigned long pltrelsize;	/* Size in bytes of PLT relocation info */
179     const Elf_Rela *pltrela;	/* PLT relocation entries with addend */
180     unsigned long pltrelasize;	/* Size in bytes of PLT addend reloc info */
181     const Elf_Sym *symtab;	/* Symbol table */
182     const char *strtab;		/* String table */
183     unsigned long strsize;	/* Size in bytes of string table */
184 #ifdef __mips__
185     Elf_Word local_gotno;	/* Number of local GOT entries */
186     Elf_Word symtabno;		/* Number of dynamic symbols */
187     Elf_Word gotsym;		/* First dynamic symbol in GOT */
188 #endif
189 
190     const Elf_Verneed *verneed; /* Required versions. */
191     Elf_Word verneednum;	/* Number of entries in verneed table */
192     const Elf_Verdef  *verdef;	/* Provided versions. */
193     Elf_Word verdefnum;		/* Number of entries in verdef table */
194     const Elf_Versym *versyms;  /* Symbol versions table */
195 
196     const Elf_Hashelt *buckets;	/* Hash table buckets array */
197     unsigned long nbuckets;	/* Number of buckets */
198     const Elf_Hashelt *chains;	/* Hash table chain array */
199     unsigned long nchains;	/* Number of chains */
200 
201     char *rpath;		/* Search path specified in object */
202     Needed_Entry *needed;	/* Shared objects needed by this one (%) */
203     Needed_Entry *needed_filtees;
204     Needed_Entry *needed_aux_filtees;
205 
206     STAILQ_HEAD(, Struct_Name_Entry) names; /* List of names for this object we
207 					       know about. */
208     Ver_Entry *vertab;		/* Versions required /defined by this object */
209     int vernum;			/* Number of entries in vertab */
210 
211     Elf_Addr init;		/* Initialization function to call */
212     Elf_Addr fini;		/* Termination function to call */
213 
214     bool mainprog : 1;		/* True if this is the main program */
215     bool rtld : 1;		/* True if this is the dynamic linker */
216     bool textrel : 1;		/* True if there are relocations to text seg */
217     bool symbolic : 1;		/* True if generated with "-Bsymbolic" */
218     bool bind_now : 1;		/* True if all relocations should be made first */
219     bool traced : 1;		/* Already printed in ldd trace output */
220     bool jmpslots_done : 1;	/* Already have relocated the jump slots */
221     bool init_done : 1;		/* Already have added object to init list */
222     bool tls_done : 1;		/* Already allocated offset for static TLS */
223     bool phdr_alloc : 1;	/* Phdr is allocated and needs to be freed. */
224     bool z_origin : 1;		/* Process rpath and soname tokens */
225     bool z_nodelete : 1;	/* Do not unload the object and dependencies */
226     bool z_noopen : 1;		/* Do not load on dlopen */
227     bool z_loadfltr : 1;	/* Immediately load filtees */
228     bool ref_nodel : 1;		/* Refcount increased to prevent dlclose */
229     bool init_scanned: 1;	/* Object is already on init list. */
230     bool on_fini_list: 1;	/* Object is already on fini list. */
231     bool dag_inited : 1;	/* Object has its DAG initialized. */
232     bool filtees_loaded : 1;	/* Filtees loaded */
233 
234     struct link_map linkmap;	/* For GDB and dlinfo() */
235     Objlist dldags;		/* Object belongs to these dlopened DAGs (%) */
236     Objlist dagmembers;		/* DAG has these members (%) */
237     dev_t dev;			/* Object's filesystem's device */
238     ino_t ino;			/* Object's inode number */
239     void *priv;			/* Platform-dependant */
240 } Obj_Entry;
241 
242 #define RTLD_MAGIC	0xd550b87a
243 #define RTLD_VERSION	1
244 
245 #define RTLD_STATIC_TLS_EXTRA	128
246 
247 /* Flags to be passed into symlook_ family of functions. */
248 #define SYMLOOK_IN_PLT	0x01	/* Lookup for PLT symbol */
249 #define SYMLOOK_DLSYM	0x02	/* Return newes versioned symbol. Used by
250 				   dlsym. */
251 
252 /* Flags for load_object(). */
253 #define	RTLD_LO_NOLOAD	0x01	/* dlopen() specified RTLD_NOLOAD. */
254 #define	RTLD_LO_DLOPEN	0x02	/* Load_object() called from dlopen(). */
255 #define	RTLD_LO_TRACE	0x04	/* Only tracing. */
256 #define	RTLD_LO_NODELETE 0x08	/* Loaded object cannot be closed. */
257 #define	RTLD_LO_FILTEES 0x10	/* Loading filtee. */
258 
259 /*
260  * Symbol cache entry used during relocation to avoid multiple lookups
261  * of the same symbol.
262  */
263 typedef struct Struct_SymCache {
264     const Elf_Sym *sym;		/* Symbol table entry */
265     const Obj_Entry *obj;	/* Shared object which defines it */
266 } SymCache;
267 
268 /*
269  * This structure provides a reentrant way to keep a list of objects and
270  * check which ones have already been processed in some way.
271  */
272 typedef struct Struct_DoneList {
273     const Obj_Entry **objs;		/* Array of object pointers */
274     unsigned int num_alloc;		/* Allocated size of the array */
275     unsigned int num_used;		/* Number of array slots used */
276 } DoneList;
277 
278 struct Struct_RtldLockState {
279 	int lockstate;
280 	sigjmp_buf env;
281 };
282 
283 /*
284  * The pack of arguments and results for the symbol lookup functions.
285  */
286 typedef struct Struct_SymLook {
287     const char *name;
288     unsigned long hash;
289     const Ver_Entry *ventry;
290     int flags;
291     const Obj_Entry *defobj_out;
292     const Elf_Sym *sym_out;
293     struct Struct_RtldLockState *lockstate;
294 } SymLook;
295 
296 extern void _rtld_error(const char *, ...) __printflike(1, 2);
297 extern Obj_Entry *map_object(int, const char *, const struct stat *);
298 extern void *xcalloc(size_t);
299 extern void *xmalloc(size_t);
300 extern char *xstrdup(const char *);
301 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
302 extern Elf_Sym sym_zero;	/* For resolving undefined weak refs. */
303 
304 extern void dump_relocations (Obj_Entry *);
305 extern void dump_obj_relocations (Obj_Entry *);
306 extern void dump_Elf_Rel (Obj_Entry *, const Elf_Rel *, u_long);
307 extern void dump_Elf_Rela (Obj_Entry *, const Elf_Rela *, u_long);
308 
309 /*
310  * Function declarations.
311  */
312 unsigned long elf_hash(const char *);
313 const Elf_Sym *find_symdef(unsigned long, const Obj_Entry *,
314   const Obj_Entry **, int, SymCache *, struct Struct_RtldLockState *);
315 void init_pltgot(Obj_Entry *);
316 void lockdflt_init(void);
317 void obj_free(Obj_Entry *);
318 Obj_Entry *obj_new(void);
319 void _rtld_bind_start(void);
320 void symlook_init(SymLook *, const char *);
321 int symlook_obj(SymLook *, const Obj_Entry *);
322 void *tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset);
323 void *allocate_tls(Obj_Entry *, void *, size_t, size_t);
324 void free_tls(void *, size_t, size_t);
325 void *allocate_module_tls(int index);
326 bool allocate_tls_offset(Obj_Entry *obj);
327 void free_tls_offset(Obj_Entry *obj);
328 const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long);
329 
330 /*
331  * MD function declarations.
332  */
333 int do_copy_relocations(Obj_Entry *);
334 int reloc_non_plt(Obj_Entry *, Obj_Entry *, struct Struct_RtldLockState *);
335 int reloc_plt(Obj_Entry *);
336 int reloc_jmpslots(Obj_Entry *, struct Struct_RtldLockState *);
337 void allocate_initial_tls(Obj_Entry *);
338 
339 #endif /* } */
340