rtld: add RELRO support
[dragonfly.git] / libexec / rtld-elf / rtld.h
CommitLineData
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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 *
fcf53d9b 25 * $FreeBSD: src/libexec/rtld-elf/rtld.h,v 1.50 2011/02/09 09:20:27 kib Exp $
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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>
fcf53d9b 37#include <setjmp.h>
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38#include <stddef.h>
39
fcf53d9b 40#include "rtld_lock.h"
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41#include "rtld_machdep.h"
42
43#ifndef STANDARD_LIBRARY_PATH
44#define STANDARD_LIBRARY_PATH "/usr/lib"
45#endif
46
47#define NEW(type) ((type *) xmalloc(sizeof(type)))
48#define CNEW(type) ((type *) xcalloc(sizeof(type)))
49
50/* We might as well do booleans like C++. */
51typedef unsigned char bool;
52#define false 0
53#define true 1
54
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55extern size_t tls_last_offset;
56extern size_t tls_last_size;
57extern size_t tls_static_space;
58extern int tls_dtv_generation;
59extern int tls_max_index;
60
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61struct stat;
62struct Struct_Obj_Entry;
63
64/* Lists of shared objects */
65typedef struct Struct_Objlist_Entry {
66 STAILQ_ENTRY(Struct_Objlist_Entry) link;
67 struct Struct_Obj_Entry *obj;
68} Objlist_Entry;
69
70typedef STAILQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
71
72/* Types of init and fini functions */
73typedef void (*InitFunc)(void);
74
75/* Lists of shared object dependencies */
76typedef struct Struct_Needed_Entry {
77 struct Struct_Needed_Entry *next;
78 struct Struct_Obj_Entry *obj;
79 unsigned long name; /* Offset of name in string table */
80} Needed_Entry;
81
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82typedef struct Struct_Name_Entry {
83 STAILQ_ENTRY(Struct_Name_Entry) link;
84 char name[1];
85} Name_Entry;
86
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87/* Lock object */
88typedef struct Struct_LockInfo {
89 void *context; /* Client context for creating locks */
90 void *thelock; /* The one big lock */
91 /* Debugging aids. */
92 volatile int rcount; /* Number of readers holding lock */
93 volatile int wcount; /* Number of writers holding lock */
94 /* Methods */
95 void *(*lock_create)(void *context);
96 void (*rlock_acquire)(void *lock);
97 void (*wlock_acquire)(void *lock);
98 void (*rlock_release)(void *lock);
99 void (*wlock_release)(void *lock);
100 void (*lock_destroy)(void *lock);
101 void (*context_destroy)(void *context);
102} LockInfo;
103
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104typedef struct Struct_Ver_Entry {
105 Elf_Word hash;
106 unsigned int flags;
107 const char *name;
108 const char *file;
109} Ver_Entry;
110
111#define VER_INFO_HIDDEN 0x01
112
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113/*
114 * Shared object descriptor.
115 *
116 * Items marked with "(%)" are dynamically allocated, and must be freed
117 * when the structure is destroyed.
118 *
119 * CAUTION: It appears that the JDK port peeks into these structures.
120 * It looks at "next" and "mapbase" at least. Don't add new members
121 * near the front, until this can be straightened out.
122 */
123typedef struct Struct_Obj_Entry {
124 /*
125 * These two items have to be set right for compatibility with the
126 * original ElfKit crt1.o.
127 */
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128 Elf_Size magic; /* Magic number (sanity check) */
129 Elf_Size version; /* Version number of struct format */
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130
131 struct Struct_Obj_Entry *next;
132 char *path; /* Pathname of underlying file (%) */
167f7029 133 char *origin_path; /* Directory path of origin file */
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134 int refcount;
135 int dl_refcount; /* Number of times loaded by dlopen */
136
137 /* These items are computed by map_object() or by digest_phdr(). */
138 caddr_t mapbase; /* Base address of mapped region */
139 size_t mapsize; /* Size of mapped region in bytes */
140 size_t textsize; /* Size of text segment in bytes */
141 Elf_Addr vaddrbase; /* Base address in shared object file */
142 caddr_t relocbase; /* Relocation constant = mapbase - vaddrbase */
143 const Elf_Dyn *dynamic; /* Dynamic section */
144 caddr_t entry; /* Entry point */
145 const Elf_Phdr *phdr; /* Program header if it is mapped, else NULL */
146 size_t phsize; /* Size of program header in bytes */
147 const char *interp; /* Pathname of the interpreter, if any */
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148 caddr_t relro_page; /* Address of first page of read-only data */
149 size_t relro_size; /* Size of relro page(s) in bytes */
984263bc 150
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151 /* TLS information */
152 int tlsindex; /* Index in DTV for this module */
153 void *tlsinit; /* Base address of TLS init block */
154 size_t tlsinitsize; /* Size of TLS init block for this module */
155 size_t tlssize; /* Size of TLS block for this module */
156 size_t tlsoffset; /* Offset of static TLS block for this module */
157 size_t tlsalign; /* Alignment of static TLS block */
158
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159 /* Items from the dynamic section. */
160 Elf_Addr *pltgot; /* PLT or GOT, depending on architecture */
161 const Elf_Rel *rel; /* Relocation entries */
162 unsigned long relsize; /* Size in bytes of relocation info */
163 const Elf_Rela *rela; /* Relocation entries with addend */
164 unsigned long relasize; /* Size in bytes of addend relocation info */
165 const Elf_Rel *pltrel; /* PLT relocation entries */
166 unsigned long pltrelsize; /* Size in bytes of PLT relocation info */
167 const Elf_Rela *pltrela; /* PLT relocation entries with addend */
168 unsigned long pltrelasize; /* Size in bytes of PLT addend reloc info */
169 const Elf_Sym *symtab; /* Symbol table */
170 const char *strtab; /* String table */
171 unsigned long strsize; /* Size in bytes of string table */
172
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173 const Elf_Verneed *verneed; /* Required versions. */
174 Elf_Word verneednum; /* Number of entries in verneed table */
175 const Elf_Verdef *verdef; /* Provided versions. */
176 Elf_Word verdefnum; /* Number of entries in verdef table */
177 const Elf_Versym *versyms; /* Symbol versions table */
178
d697cc44 179 const Elf_Hashelt *buckets; /* Hash table buckets array */
984263bc 180 unsigned long nbuckets; /* Number of buckets */
d697cc44 181 const Elf_Hashelt *chains; /* Hash table chain array */
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182 unsigned long nchains; /* Number of chains */
183
fcf53d9b 184 char *rpath; /* Search path specified in object */
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185 Needed_Entry *needed; /* Shared objects needed by this one (%) */
186
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187 STAILQ_HEAD(, Struct_Name_Entry) names; /* List of names for this object we
188 know about. */
189 Ver_Entry *vertab; /* Versions required /defined by this object */
190 int vernum; /* Number of entries in vertab */
191
192 Elf_Addr init; /* Initialization function to call */
193 Elf_Addr fini; /* Termination function to call */
194
195 bool mainprog : 1; /* True if this is the main program */
196 bool rtld : 1; /* True if this is the dynamic linker */
197 bool textrel : 1; /* True if there are relocations to text seg */
198 bool symbolic : 1; /* True if generated with "-Bsymbolic" */
199 bool bind_now : 1; /* True if all relocations should be made first */
200 bool traced : 1; /* Already printed in ldd trace output */
201 bool jmpslots_done : 1; /* Already have relocated the jump slots */
202 bool init_done : 1; /* Already have added object to init list */
203 bool tls_done : 1; /* Already allocated offset for static TLS */
204 bool phdr_alloc : 1; /* Phdr is allocated and needs to be freed. */
205 bool z_origin : 1; /* Process rpath and soname tokens */
206 bool z_nodelete : 1; /* Do not unload the object and dependencies */
207 bool z_noopen : 1; /* Do not load on dlopen */
208 bool ref_nodel : 1; /* Refcount increased to prevent dlclose */
209 bool init_scanned: 1; /* Object is already on init list. */
210 bool on_fini_list: 1; /* Object is already on fini list. */
211 bool dag_inited : 1; /* Object has its DAG initialized. */
212
213 struct link_map linkmap; /* For GDB and dlinfo() */
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214 Objlist dldags; /* Object belongs to these dlopened DAGs (%) */
215 Objlist dagmembers; /* DAG has these members (%) */
216 dev_t dev; /* Object's filesystem's device */
217 ino_t ino; /* Object's inode number */
30aefd4f 218 void *priv; /* Platform-dependent */
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219} Obj_Entry;
220
221#define RTLD_MAGIC 0xd550b87a
222#define RTLD_VERSION 1
223
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224/* Flags to be passed into symlook_ family of functions. */
225#define SYMLOOK_IN_PLT 0x01 /* Lookup for PLT symbol */
30aefd4f 226#define SYMLOOK_DLSYM 0x02 /* Return newest versioned symbol. Used by
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227 dlsym. */
228
229/* Flags for load_object(). */
230#define RTLD_LO_NOLOAD 0x01 /* dlopen() specified RTLD_NOLOAD. */
231#define RTLD_LO_DLOPEN 0x02 /* Load_object() called from dlopen(). */
232#define RTLD_LO_TRACE 0x04 /* Only tracing. */
233#define RTLD_LO_NODELETE 0x08 /* Loaded object cannot be closed. */
234
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235/*
236 * Symbol cache entry used during relocation to avoid multiple lookups
237 * of the same symbol.
238 */
239typedef struct Struct_SymCache {
240 const Elf_Sym *sym; /* Symbol table entry */
241 const Obj_Entry *obj; /* Shared object which defines it */
242} SymCache;
243
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244struct Struct_RtldLockState {
245 int lockstate;
246 sigjmp_buf env;
247};
248
249void _rtld_error(const char *, ...) __printflike(1, 2);
250Obj_Entry *map_object(int, const char *, const struct stat *);
251void *xcalloc(size_t);
252void *xmalloc(size_t);
253char *xstrdup(const char *);
254void *xrealloc(void *, size_t);
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255extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
256
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257void dump_relocations(Obj_Entry *);
258void dump_obj_relocations(Obj_Entry *);
259void dump_Elf_Rel(Obj_Entry *, const Elf_Rel *, u_long);
260void dump_Elf_Rela(Obj_Entry *, const Elf_Rela *, u_long);
261
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262/*
263 * Function declarations.
264 */
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265const char *basename(const char *);
266unsigned long elf_hash(const char *);
267const Elf_Sym *find_symdef(unsigned long, const Obj_Entry *,
268 const Obj_Entry **, int, SymCache *);
269void init_pltgot(Obj_Entry *);
270void lockdflt_init(void);
271void obj_free(Obj_Entry *);
272Obj_Entry *obj_new(void);
273void _rtld_bind_start(void);
7fc47990 274const Elf_Sym *symlook_obj(const char *, unsigned long, const Obj_Entry *,
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275 const Ver_Entry *, int);
276void *tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset);
a1eee96a 277struct tls_tcb *allocate_tls(Obj_Entry *);
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278void free_tls(struct tls_tcb *);
279void *allocate_module_tls(int index);
280bool allocate_tls_offset(Obj_Entry *obj);
281void free_tls_offset(Obj_Entry *obj);
282const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long);
283
284/*
285 * MD function declarations.
286 */
287int do_copy_relocations(Obj_Entry *);
288int reloc_non_plt(Obj_Entry *, Obj_Entry *);
289int reloc_plt(Obj_Entry *);
290int reloc_jmpslots(Obj_Entry *);
291void allocate_initial_tls(Obj_Entry *);
139b8f34 292
984263bc 293#endif /* } */