xref: /freebsd/libexec/rtld-elf/rtld.h (revision c66ec88fed842fbaad62c30d510644ceb7bd2d71)
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 <stdbool.h>
41 #include <setjmp.h>
42 #include <stddef.h>
43 
44 #include "rtld_lock.h"
45 #include "rtld_machdep.h"
46 
47 #define NEW(type)	((type *) xmalloc(sizeof(type)))
48 #define CNEW(type)	((type *) xcalloc(1, sizeof(type)))
49 
50 extern size_t tls_last_offset;
51 extern size_t tls_last_size;
52 extern size_t tls_static_space;
53 extern Elf_Addr tls_dtv_generation;
54 extern int tls_max_index;
55 
56 extern int npagesizes;
57 extern size_t *pagesizes;
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     caddr_t relro_page;
169     size_t relro_size;
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     Elf_Addr *mips_pltgot;	/* Second PLT GOT */
189 #endif
190 #ifdef __powerpc__
191 #ifdef __powerpc64__
192     Elf_Addr glink;		/* GLINK PLT call stub section */
193 #else
194     Elf_Addr *gotptr;		/* GOT pointer (secure-plt only) */
195 #endif
196 #endif
197 
198     const Elf_Verneed *verneed; /* Required versions. */
199     Elf_Word verneednum;	/* Number of entries in verneed table */
200     const Elf_Verdef  *verdef;	/* Provided versions. */
201     Elf_Word verdefnum;		/* Number of entries in verdef table */
202     const Elf_Versym *versyms;  /* Symbol versions table */
203 
204     const Elf_Hashelt *buckets;	/* Hash table buckets array */
205     unsigned long nbuckets;	/* Number of buckets */
206     const Elf_Hashelt *chains;	/* Hash table chain array */
207     unsigned long nchains;	/* Number of entries in chain array */
208 
209     Elf32_Word nbuckets_gnu;		/* Number of GNU hash buckets*/
210     Elf32_Word symndx_gnu;		/* 1st accessible symbol on dynsym table */
211     Elf32_Word maskwords_bm_gnu;  	/* Bloom filter words - 1 (bitmask) */
212     Elf32_Word shift2_gnu;		/* Bloom filter shift count */
213     Elf32_Word dynsymcount;		/* Total entries in dynsym table */
214     const Elf_Addr *bloom_gnu;		/* Bloom filter used by GNU hash func */
215     const Elf_Hashelt *buckets_gnu;	/* GNU hash table bucket array */
216     const Elf_Hashelt *chain_zero_gnu;	/* GNU hash table value array (Zeroed) */
217 
218     const char *rpath;		/* Search path specified in object */
219     const char *runpath;	/* Search path with different priority */
220     Needed_Entry *needed;	/* Shared objects needed by this one (%) */
221     Needed_Entry *needed_filtees;
222     Needed_Entry *needed_aux_filtees;
223 
224     STAILQ_HEAD(, Struct_Name_Entry) names; /* List of names for this object we
225 					       know about. */
226     Ver_Entry *vertab;		/* Versions required /defined by this object */
227     int vernum;			/* Number of entries in vertab */
228 
229     Elf_Addr init;		/* Initialization function to call */
230     Elf_Addr fini;		/* Termination function to call */
231     Elf_Addr preinit_array;	/* Pre-initialization array of functions */
232     Elf_Addr init_array;	/* Initialization array of functions */
233     Elf_Addr fini_array;	/* Termination array of functions */
234     int preinit_array_num;	/* Number of entries in preinit_array */
235     int init_array_num; 	/* Number of entries in init_array */
236     int fini_array_num; 	/* Number of entries in fini_array */
237 
238     int32_t osrel;		/* OSREL note value */
239     uint32_t fctl0;		/* FEATURE_CONTROL note desc[0] value */
240 
241     bool mainprog : 1;		/* True if this is the main program */
242     bool rtld : 1;		/* True if this is the dynamic linker */
243     bool relocated : 1;		/* True if processed by relocate_objects() */
244     bool ver_checked : 1;	/* True if processed by rtld_verify_object_versions */
245     bool textrel : 1;		/* True if there are relocations to text seg */
246     bool symbolic : 1;		/* True if generated with "-Bsymbolic" */
247     bool bind_now : 1;		/* True if all relocations should be made first */
248     bool traced : 1;		/* Already printed in ldd trace output */
249     bool jmpslots_done : 1;	/* Already have relocated the jump slots */
250     bool init_done : 1;		/* Already have added object to init list */
251     bool tls_done : 1;		/* Already allocated offset for static TLS */
252     bool phdr_alloc : 1;	/* Phdr is allocated and needs to be freed. */
253     bool z_origin : 1;		/* Process rpath and soname tokens */
254     bool z_nodelete : 1;	/* Do not unload the object and dependencies */
255     bool z_noopen : 1;		/* Do not load on dlopen */
256     bool z_loadfltr : 1;	/* Immediately load filtees */
257     bool z_interpose : 1;	/* Interpose all objects but main */
258     bool z_nodeflib : 1;	/* Don't search default library path */
259     bool z_global : 1;		/* Make the object global */
260     bool z_pie : 1;		/* Object proclaimed itself PIE executable */
261     bool static_tls : 1;	/* Needs static TLS allocation */
262     bool static_tls_copied : 1;	/* Needs static TLS copying */
263     bool ref_nodel : 1;		/* Refcount increased to prevent dlclose */
264     bool init_scanned: 1;	/* Object is already on init list. */
265     bool on_fini_list: 1;	/* Object is already on fini list. */
266     bool dag_inited : 1;	/* Object has its DAG initialized. */
267     bool filtees_loaded : 1;	/* Filtees loaded */
268     bool irelative : 1;		/* Object has R_MACHDEP_IRELATIVE relocs */
269     bool irelative_nonplt : 1;	/* Object has R_MACHDEP_IRELATIVE non-plt relocs */
270     bool gnu_ifunc : 1;		/* Object has references to STT_GNU_IFUNC */
271     bool non_plt_gnu_ifunc : 1;	/* Object has non-plt IFUNC references */
272     bool ifuncs_resolved : 1;	/* Object ifuncs were already resolved */
273     bool crt_no_init : 1;	/* Object' crt does not call _init/_fini */
274     bool valid_hash_sysv : 1;	/* A valid System V hash hash tag is available */
275     bool valid_hash_gnu : 1;	/* A valid GNU hash tag is available */
276     bool dlopened : 1;		/* dlopen()-ed (vs. load statically) */
277     bool marker : 1;		/* marker on the global obj list */
278     bool unholdfree : 1;	/* unmap upon last unhold */
279     bool doomed : 1;		/* Object cannot be referenced */
280 
281     struct link_map linkmap;	/* For GDB and dlinfo() */
282     Objlist dldags;		/* Object belongs to these dlopened DAGs (%) */
283     Objlist dagmembers;		/* DAG has these members (%) */
284     dev_t dev;			/* Object's filesystem's device */
285     ino_t ino;			/* Object's inode number */
286     void *priv;			/* Platform-dependent */
287 } Obj_Entry;
288 
289 #define RTLD_MAGIC	0xd550b87a
290 #define RTLD_VERSION	1
291 
292 TAILQ_HEAD(obj_entry_q, Struct_Obj_Entry);
293 
294 #define RTLD_STATIC_TLS_EXTRA	128
295 
296 /* Flags to be passed into symlook_ family of functions. */
297 #define SYMLOOK_IN_PLT	0x01	/* Lookup for PLT symbol */
298 #define SYMLOOK_DLSYM	0x02	/* Return newest versioned symbol. Used by
299 				   dlsym. */
300 #define	SYMLOOK_EARLY	0x04	/* Symlook is done during initialization. */
301 #define	SYMLOOK_IFUNC	0x08	/* Allow IFUNC processing in
302 				   reloc_non_plt(). */
303 
304 /* Flags for load_object(). */
305 #define	RTLD_LO_NOLOAD	0x01	/* dlopen() specified RTLD_NOLOAD. */
306 #define	RTLD_LO_DLOPEN	0x02	/* Load_object() called from dlopen(). */
307 #define	RTLD_LO_TRACE	0x04	/* Only tracing. */
308 #define	RTLD_LO_NODELETE 0x08	/* Loaded object cannot be closed. */
309 #define	RTLD_LO_FILTEES 0x10	/* Loading filtee. */
310 #define	RTLD_LO_EARLY	0x20	/* Do not call ctors, postpone it to the
311 				   initialization during the image start. */
312 #define	RTLD_LO_IGNSTLS 0x40	/* Do not allocate static TLS */
313 #define	RTLD_LO_DEEPBIND 0x80	/* Force symbolic for this object */
314 
315 /*
316  * Symbol cache entry used during relocation to avoid multiple lookups
317  * of the same symbol.
318  */
319 typedef struct Struct_SymCache {
320     const Elf_Sym *sym;		/* Symbol table entry */
321     const Obj_Entry *obj;	/* Shared object which defines it */
322 } SymCache;
323 
324 /*
325  * This structure provides a reentrant way to keep a list of objects and
326  * check which ones have already been processed in some way.
327  */
328 typedef struct Struct_DoneList {
329     const Obj_Entry **objs;		/* Array of object pointers */
330     unsigned int num_alloc;		/* Allocated size of the array */
331     unsigned int num_used;		/* Number of array slots used */
332 } DoneList;
333 
334 struct Struct_RtldLockState {
335 	int lockstate;
336 	sigjmp_buf env;
337 };
338 
339 struct fill_search_info_args {
340 	int request;
341 	unsigned int flags;
342 	struct dl_serinfo *serinfo;
343 	struct dl_serpath *serpath;
344 	char *strspace;
345 };
346 
347 /*
348  * The pack of arguments and results for the symbol lookup functions.
349  */
350 typedef struct Struct_SymLook {
351     const char *name;
352     unsigned long hash;
353     uint32_t hash_gnu;
354     const Ver_Entry *ventry;
355     int flags;
356     const Obj_Entry *defobj_out;
357     const Elf_Sym *sym_out;
358     struct Struct_RtldLockState *lockstate;
359 } SymLook;
360 
361 void _rtld_error(const char *, ...) __printflike(1, 2) __exported;
362 void rtld_die(void) __dead2;
363 const char *rtld_strerror(int);
364 Obj_Entry *map_object(int, const char *, const struct stat *);
365 void *xcalloc(size_t, size_t);
366 void *xmalloc(size_t);
367 char *xstrdup(const char *);
368 void *malloc_aligned(size_t size, size_t align, size_t offset);
369 void free_aligned(void *ptr);
370 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
371 extern Elf_Sym sym_zero;	/* For resolving undefined weak refs. */
372 extern bool ld_bind_not;
373 extern bool ld_fast_sigblock;
374 
375 void dump_relocations(Obj_Entry *);
376 void dump_obj_relocations(Obj_Entry *);
377 void dump_Elf_Rel(Obj_Entry *, const Elf_Rel *, u_long);
378 void dump_Elf_Rela(Obj_Entry *, const Elf_Rela *, u_long);
379 
380 /*
381  * Function declarations.
382  */
383 unsigned long elf_hash(const char *);
384 const Elf_Sym *find_symdef(unsigned long, const Obj_Entry *,
385   const Obj_Entry **, int, SymCache *, struct Struct_RtldLockState *);
386 void lockdflt_init(void);
387 void digest_notes(Obj_Entry *, Elf_Addr, Elf_Addr);
388 Obj_Entry *globallist_curr(const Obj_Entry *obj);
389 Obj_Entry *globallist_next(const Obj_Entry *obj);
390 void obj_free(Obj_Entry *);
391 Obj_Entry *obj_new(void);
392 void _rtld_bind_start(void);
393 void *rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def);
394 void symlook_init(SymLook *, const char *);
395 int symlook_obj(SymLook *, const Obj_Entry *);
396 void *tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset);
397 void *allocate_tls(Obj_Entry *, void *, size_t, size_t);
398 void free_tls(void *, size_t, size_t);
399 void *allocate_module_tls(int index);
400 bool allocate_tls_offset(Obj_Entry *obj);
401 void free_tls_offset(Obj_Entry *obj);
402 const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long);
403 int convert_prot(int elfflags);
404 
405 /*
406  * MD function declarations.
407  */
408 int do_copy_relocations(Obj_Entry *);
409 int reloc_non_plt(Obj_Entry *, Obj_Entry *, int flags,
410     struct Struct_RtldLockState *);
411 int reloc_plt(Obj_Entry *, int flags, struct Struct_RtldLockState *);
412 int reloc_jmpslots(Obj_Entry *, int flags, struct Struct_RtldLockState *);
413 int reloc_iresolve(Obj_Entry *, struct Struct_RtldLockState *);
414 int reloc_iresolve_nonplt(Obj_Entry *, struct Struct_RtldLockState *);
415 int reloc_gnu_ifunc(Obj_Entry *, int flags, struct Struct_RtldLockState *);
416 void ifunc_init(Elf_Auxinfo[__min_size(AT_COUNT)]);
417 void init_pltgot(Obj_Entry *);
418 void allocate_initial_tls(Obj_Entry *);
419 
420 void *__crt_calloc(size_t num, size_t size);
421 void __crt_free(void *cp);
422 void *__crt_malloc(size_t nbytes);
423 void *__crt_realloc(void *cp, size_t nbytes);
424 
425 #endif /* } */
426