libexec/ld.elf_so/rtld.h

   1 /*      $NetBSD: rtld.h,v 1.124 2014/09/19 17:43:33 matt Exp $   */
   2
   3 /*
   4  * Copyright 1996 John D. Polstra.
   5  * Copyright 1996 Matt Thomas <matt@3am-software.com>
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by John Polstra.
  19  * 4. The name of the author may not be used to endorse or promote products
  20  *    derived from this software without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  23  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  24  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  25  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  27  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  28  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  31  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #ifndef RTLD_H
  35 #define RTLD_H
  36
  37 #include <dlfcn.h>
  38 #include <signal.h>
  39 #include <stdbool.h>
  40 #include <stddef.h>
  41 #include <sys/param.h>
  42 #include <sys/types.h>
  43 #include <sys/queue.h>
  44 #include <sys/exec_elf.h>
  45 #include <sys/tls.h>
  46 #include "rtldenv.h"
  47 #include "link.h"
  48
  49 #if defined(_RTLD_SOURCE)
  50
  51 #if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__)
  52 #include "unwind.h"
  53 #endif
  54
  55 #ifndef RTLD_DEFAULT_LIBRARY_PATH
  56 #define RTLD_DEFAULT_LIBRARY_PATH       "/usr/lib"
  57 #endif
  58 #define _PATH_LD_HINTS                  "/etc/ld.so.conf"
  59
  60 extern size_t _rtld_pagesz;
  61
  62 #define round_down(x)   ((x) & ~(_rtld_pagesz - 1))
  63 #define round_up(x)     round_down((x) + _rtld_pagesz - 1)
  64
  65 #define NEW(type)       ((type *) xmalloc(sizeof(type)))
  66 #define CNEW(type)      ((type *) xcalloc(sizeof(type)))
  67
  68 /*
  69  * Fill in a DoneList with an allocation large enough to hold all of
  70  * the currently-loaded objects. Keep this in a macro since it calls
  71  * alloca and we want that to occur within the scope of the caller.
  72  */
  73 #define _rtld_donelist_init(dlp)                                        \
  74     ((dlp)->num_alloc = _rtld_objcount,                                 \
  75     (dlp)->objs = alloca((dlp)->num_alloc * sizeof((dlp)->objs[0])),    \
  76     assert((dlp)->objs != NULL),                                        \
  77     (dlp)->num_used = 0)
  78
  79 #endif /* _RTLD_SOURCE */
  80
  81 /*
  82  * C++ has mandated the use of the following keywords for its new boolean
  83  * type.  We might as well follow their lead.
  84  */
  85 struct Struct_Obj_Entry;
  86
  87 typedef struct Struct_Objlist_Entry {
  88         SIMPLEQ_ENTRY(Struct_Objlist_Entry) link;
  89         struct Struct_Obj_Entry *obj;
  90 } Objlist_Entry;
  91
  92 typedef SIMPLEQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
  93
  94 typedef struct Struct_Name_Entry {
  95         SIMPLEQ_ENTRY(Struct_Name_Entry) link;
  96         char    name[1];
  97 } Name_Entry;
  98
  99 typedef struct Struct_Needed_Entry {
 100         struct Struct_Needed_Entry *next;
 101         struct Struct_Obj_Entry *obj;
 102         unsigned long   name;   /* Offset of name in string table */
 103 } Needed_Entry;
 104
 105 typedef struct _rtld_search_path_t {
 106         struct _rtld_search_path_t *sp_next;
 107         const char     *sp_path;
 108         size_t          sp_pathlen;
 109 } Search_Path;
 110
 111 typedef struct Struct_Ver_Entry {
 112         Elf_Word        hash;
 113         u_int           flags;
 114         const char     *name;
 115         const char     *file;
 116 } Ver_Entry;
 117
 118 /* Ver_Entry.flags */
 119 #define VER_INFO_HIDDEN 0x01
 120
 121 #define RTLD_MAX_ENTRY 10
 122 #define RTLD_MAX_LIBRARY 4
 123 #define RTLD_MAX_CTL 2
 124 typedef struct _rtld_library_xform_t {
 125         struct _rtld_library_xform_t *next;
 126         char *name;
 127         const char *ctlname;
 128         struct {
 129                 char *value;
 130                 char *library[RTLD_MAX_LIBRARY];
 131         } entry[RTLD_MAX_ENTRY];
 132 } Library_Xform;
 133
 134 /*
 135  * Shared object descriptor.
 136  *
 137  * Items marked with "(%)" are dynamically allocated, and must be freed
 138  * when the structure is destroyed.
 139  *
 140  * The layout of this structure needs to be preserved because pre-2.0 binaries
 141  * hard-coded the location of dlopen() and friends.
 142  */
 143
 144 #define RTLD_MAGIC      0xd550b87a
 145 #define RTLD_VERSION    1
 146
 147 typedef void (*fptr_t)(void);
 148
 149 typedef struct Struct_Obj_Entry {
 150         Elf32_Word      magic;          /* Magic number (sanity check) */
 151         Elf32_Word      version;        /* Version number of struct format */
 152
 153         struct Struct_Obj_Entry *next;
 154         char           *path;           /* Pathname of underlying file (%) */
 155         int             refcount;
 156         int             dl_refcount;    /* Number of times loaded by dlopen */
 157
 158         /* These items are computed by map_object() or by digest_phdr(). */
 159         caddr_t         mapbase;        /* Base address of mapped region */
 160         size_t          mapsize;        /* Size of mapped region in bytes */
 161         size_t          textsize;       /* Size of text segment in bytes */
 162         Elf_Addr        vaddrbase;      /* Base address in shared object file */
 163         caddr_t         relocbase;      /* Reloc const = mapbase - *vaddrbase */
 164         Elf_Dyn        *dynamic;        /* Dynamic section */
 165         caddr_t         entry;          /* Entry point */
 166         const Elf_Phdr *phdr;           /* Program header (may be xmalloc'ed) */
 167         size_t          phsize;         /* Size of program header in bytes */
 168
 169         /* Items from the dynamic section. */
 170         Elf_Addr       *pltgot;         /* PLTGOT table */
 171         const Elf_Rel  *rel;            /* Relocation entries */
 172         const Elf_Rel  *rellim;         /* Limit of Relocation entries */
 173         const Elf_Rela *rela;           /* Relocation entries */
 174         const Elf_Rela *relalim;        /* Limit of Relocation entries */
 175         const Elf_Rel  *pltrel;         /* PLT relocation entries */
 176         const Elf_Rel  *pltrellim;      /* Limit of PLT relocation entries */
 177         const Elf_Rela *pltrela;        /* PLT relocation entries */
 178         const Elf_Rela *pltrelalim;     /* Limit of PLT relocation entries */
 179         const Elf_Sym  *symtab;         /* Symbol table */
 180         const char     *strtab;         /* String table */
 181         unsigned long   strsize;        /* Size in bytes of string table */
 182 #if defined(__mips__) || defined(__riscv__)
 183         Elf_Word        local_gotno;    /* Number of local GOT entries */
 184         Elf_Word        symtabno;       /* Number of dynamic symbols */
 185         Elf_Word        gotsym;         /* First dynamic symbol in GOT */
 186 #endif
 187
 188         const Elf_Symindx *buckets;     /* Hash table buckets array */
 189         unsigned long   unused1;        /* Used to be nbuckets */
 190         const Elf_Symindx *chains;      /* Hash table chain array */
 191         unsigned long   nchains;        /* Number of chains */
 192
 193         Search_Path    *rpaths;         /* Search path specified in object */
 194         Needed_Entry   *needed;         /* Shared objects needed by this (%) */
 195
 196         Elf_Addr        init;           /* Initialization function to call */
 197         Elf_Addr        fini;           /* Termination function to call */
 198
 199         /*
 200          * BACKWARDS COMPAT Entry points for dlopen() and friends.
 201          *
 202          * DO NOT MOVE OR ADD TO THE LIST
 203          *
 204          */
 205         void           *(*dlopen)(const char *, int);
 206         void           *(*dlsym)(void *, const char *);
 207         char           *(*dlerror)(void);
 208         int             (*dlclose)(void *);
 209         int             (*dladdr)(const void *, Dl_info *);
 210
 211         u_int32_t       mainprog:1,     /* True if this is the main program */
 212                         rtld:1,         /* True if this is the dynamic linker */
 213                         textrel:1,      /* True if there are relocations to
 214                                          * text seg */
 215                         symbolic:1,     /* True if generated with
 216                                          * "-Bsymbolic" */
 217                         printed:1,      /* True if ldd has printed it */
 218                         isdynamic:1,    /* True if this is a pure PIC object */
 219                         mainref:1,      /* True if on _rtld_list_main */
 220                         globalref:1,    /* True if on _rtld_list_global */
 221                         init_done:1,    /* True if .init has been added */
 222                         init_called:1,  /* True if .init function has been
 223                                          * called */
 224                         fini_called:1,  /* True if .fini function has been
 225                                          * called */
 226                         z_now:1,        /* True if object's symbols should be
 227                                            bound immediately */
 228                         z_nodelete:1,   /* True if object should never be
 229                                            unloaded */
 230                         z_initfirst:1,  /* True if object's .init/.fini take
 231                                          * priority over others */
 232                         z_noopen:1,     /* True if object should never be
 233                                            dlopen'ed */
 234                         phdr_loaded:1,  /* Phdr is loaded and doesn't need to
 235                                          * be freed. */
 236 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
 237                         tls_done:1,     /* True if static TLS offset
 238                                          * has been allocated */
 239 #endif
 240                         ref_nodel:1;    /* Refcount increased to prevent dlclose */
 241
 242         struct link_map linkmap;        /* for GDB */
 243
 244         /* These items are computed by map_object() or by digest_phdr(). */
 245         const char     *interp; /* Pathname of the interpreter, if any */
 246         Objlist         dldags; /* Object belongs to these dlopened DAGs (%) */
 247         Objlist         dagmembers;     /* DAG has these members (%) */
 248         dev_t           dev;            /* Object's filesystem's device */
 249         ino_t           ino;            /* Object's inode number */
 250
 251         void            *ehdr;
 252
 253         uint32_t        nbuckets;       /* Number of buckets */
 254         uint32_t        nbuckets_m;     /* Precomputed for fast remainder */
 255         uint8_t         nbuckets_s1;
 256         uint8_t         nbuckets_s2;
 257         size_t          pathlen;        /* Pathname length */
 258         SIMPLEQ_HEAD(, Struct_Name_Entry) names; /* List of names for this
 259                                                   * object we know about. */
 260
 261 #ifdef __powerpc__
 262 #ifdef _LP64
 263         Elf_Addr        glink;          /* global linkage */
 264 #else
 265         Elf_Addr       *gotptr;         /* GOT table (secure-plt only) */
 266 #endif
 267 #endif
 268
 269 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
 270         /* Thread Local Storage support for this module */
 271         size_t          tlsindex;       /* Index in DTV */
 272         void            *tlsinit;       /* Base address of TLS init block */
 273         size_t          tlsinitsize;    /* Size of TLS init block */
 274         size_t          tlssize;        /* Size of TLS block */
 275         size_t          tlsoffset;      /* Offset in the static TLS block */
 276         size_t          tlsalign;       /* Needed alignment for static TLS */
 277 #endif
 278
 279         /* symbol versioning */
 280         const Elf_Verneed *verneed;     /* Required versions. */
 281         Elf_Word        verneednum;     /* Number of entries in verneed table */
 282         const Elf_Verdef  *verdef;      /* Provided versions. */
 283         Elf_Word        verdefnum;      /* Number of entries in verdef table */
 284         const Elf_Versym *versyms;      /* Symbol versions table */
 285
 286         Ver_Entry       *vertab;        /* Versions required/defined by this
 287                                          * object */
 288         int             vertabnum;      /* Number of entries in vertab */
 289
 290         /* init_array/fini_array */
 291         Elf_Addr        *init_array;    /* start of init array */
 292         size_t          init_arraysz;   /* # of entries in it */
 293         Elf_Addr        *fini_array;    /* start of fini array */
 294         size_t          fini_arraysz;   /* # of entries in it */
 295 #ifdef __ARM_EABI__
 296         void            *exidx_start;
 297         size_t          exidx_sz;
 298 #endif
 299 } Obj_Entry;
 300
 301 typedef struct Struct_DoneList {
 302         const Obj_Entry **objs;         /* Array of object pointers */
 303         unsigned int num_alloc;         /* Allocated size of the array */
 304         unsigned int num_used;          /* Number of array slots used */
 305 } DoneList;
 306
 307
 308 #if defined(_RTLD_SOURCE)
 309
 310 extern struct r_debug _rtld_debug;
 311 extern Search_Path *_rtld_default_paths;
 312 extern Obj_Entry *_rtld_objlist;
 313 extern Obj_Entry **_rtld_objtail;
 314 extern u_int _rtld_objcount;
 315 extern u_int _rtld_objloads;
 316 extern Obj_Entry *_rtld_objmain;
 317 extern Obj_Entry _rtld_objself;
 318 extern Search_Path *_rtld_paths;
 319 extern Library_Xform *_rtld_xforms;
 320 extern bool _rtld_trust;
 321 extern Objlist _rtld_list_global;
 322 extern Objlist _rtld_list_main;
 323 extern Elf_Sym _rtld_sym_zero;
 324
 325 #define RTLD_MODEMASK 0x3
 326
 327 /* Flags to be passed into _rtld_symlook_ family of functions. */
 328 #define SYMLOOK_IN_PLT  0x01    /* Lookup for PLT symbol */
 329 #define SYMLOOK_DLSYM   0x02    /* Return newest versioned symbol.
 330                                    Used by dlsym. */
 331
 332 /* Flags for _rtld_load_object() and friends. */
 333 #define _RTLD_GLOBAL    0x01    /* Add object to global DAG. */
 334 #define _RTLD_MAIN      0x02
 335 #define _RTLD_NOLOAD    0x04    /* dlopen() specified RTLD_NOLOAD. */
 336 #define _RTLD_DLOPEN    0x08    /* Load_object() called from dlopen(). */
 337
 338 /* Preallocation for static TLS model */
 339 #define RTLD_STATIC_TLS_RESERVATION     64
 340
 341 /* rtld.c */
 342
 343 /* We export these symbols using _rtld_symbol_lookup and is_exported. */
 344 __dso_public char *dlerror(void);
 345 __dso_public void *dlopen(const char *, int);
 346 __dso_public void *dlsym(void *, const char *);
 347 __dso_public int dlclose(void *);
 348 __dso_public int dladdr(const void *, Dl_info *);
 349 __dso_public int dlinfo(void *, int, void *);
 350 __dso_public int dl_iterate_phdr(int (*)(struct dl_phdr_info *, size_t, void *),
 351     void *);
 352
 353 __dso_public void *_dlauxinfo(void) __pure;
 354
 355 #if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__)
 356 /*
 357  * This is used by libgcc to find the start and length of the exception table
 358  * associated with a PC.
 359  */
 360 __dso_public _Unwind_Ptr __gnu_Unwind_Find_exidx(_Unwind_Ptr, int *);
 361 #endif
 362
 363 /* These aren't exported */
 364 void _rtld_error(const char *, ...) __printflike(1,2);
 365 void _rtld_die(void) __dead;
 366 void *_rtld_objmain_sym(const char *);
 367 __dso_public void _rtld_debug_state(void) __noinline;
 368 void _rtld_linkmap_add(Obj_Entry *);
 369 void _rtld_linkmap_delete(Obj_Entry *);
 370 void _rtld_objlist_push_head(Objlist *, Obj_Entry *);
 371 void _rtld_objlist_push_tail(Objlist *, Obj_Entry *);
 372 Objlist_Entry *_rtld_objlist_find(Objlist *, const Obj_Entry *);
 373 void _rtld_ref_dag(Obj_Entry *);
 374
 375 void _rtld_shared_enter(void);
 376 void _rtld_shared_exit(void);
 377 void _rtld_exclusive_enter(sigset_t *);
 378 void _rtld_exclusive_exit(sigset_t *);
 379
 380 /* expand.c */
 381 size_t _rtld_expand_path(char *, size_t, const char *, const char *,\
 382     const char *);
 383
 384 /* headers.c */
 385 void _rtld_digest_dynamic(const char *, Obj_Entry *);
 386 Obj_Entry *_rtld_digest_phdr(const Elf_Phdr *, int, caddr_t);
 387
 388 /* load.c */
 389 Obj_Entry *_rtld_load_object(const char *, int);
 390 int _rtld_load_needed_objects(Obj_Entry *, int);
 391 int _rtld_preload(const char *);
 392
 393 #define OBJ_ERR (Obj_Entry *)(-1)
 394 /* path.c */
 395 void _rtld_add_paths(const char *, Search_Path **, const char *);
 396 void _rtld_process_hints(const char *, Search_Path **, Library_Xform **,
 397     const char *);
 398 int _rtld_sysctl(const char *, void *, size_t *);
 399
 400 /* reloc.c */
 401 int _rtld_do_copy_relocations(const Obj_Entry *);
 402 int _rtld_relocate_objects(Obj_Entry *, bool);
 403 int _rtld_relocate_nonplt_objects(Obj_Entry *);
 404 int _rtld_relocate_plt_lazy(const Obj_Entry *);
 405 int _rtld_relocate_plt_objects(const Obj_Entry *);
 406 void _rtld_setup_pltgot(const Obj_Entry *);
 407 Elf_Addr _rtld_resolve_ifunc(const Obj_Entry *, const Elf_Sym *);
 408
 409 /* search.c */
 410 Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int);
 411
 412 /* symbol.c */
 413 unsigned long _rtld_elf_hash(const char *);
 414 const Elf_Sym *_rtld_symlook_obj(const char *, unsigned long,
 415     const Obj_Entry *, u_int, const Ver_Entry *);
 416 const Elf_Sym *_rtld_find_symdef(unsigned long, const Obj_Entry *,
 417     const Obj_Entry **, u_int);
 418 const Elf_Sym *_rtld_find_plt_symdef(unsigned long, const Obj_Entry *,
 419     const Obj_Entry **, bool);
 420
 421 const Elf_Sym *_rtld_symlook_list(const char *, unsigned long,
 422     const Objlist *, const Obj_Entry **, u_int, const Ver_Entry *, DoneList *);
 423 const Elf_Sym *_rtld_symlook_default(const char *, unsigned long,
 424     const Obj_Entry *, const Obj_Entry **, u_int, const Ver_Entry *);
 425 const Elf_Sym *_rtld_symlook_needed(const char *, unsigned long,
 426     const Needed_Entry *, const Obj_Entry **, u_int, const Ver_Entry *,
 427     DoneList *, DoneList *);
 428 #ifdef COMBRELOC
 429 void _rtld_combreloc_reset(const Obj_Entry *);
 430 #endif
 431
 432 /* symver.c */
 433 void _rtld_object_add_name(Obj_Entry *, const char *);
 434 int _rtld_object_match_name(const Obj_Entry *, const char *);
 435 int _rtld_verify_object_versions(Obj_Entry *);
 436
 437 static __inline const Ver_Entry *
 438 _rtld_fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
 439 {
 440         Elf_Half vernum;
 441
 442         if (obj->vertab) {
 443                 vernum = VER_NDX(obj->versyms[symnum].vs_vers);
 444                 if (vernum >= obj->vertabnum) {
 445                         _rtld_error("%s: symbol %s has wrong verneed value %d",
 446                             obj->path, &obj->strtab[symnum], vernum);
 447                 } else if (obj->vertab[vernum].hash) {
 448                         return &obj->vertab[vernum];
 449                 }
 450         }
 451         return NULL;
 452 }
 453
 454 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
 455 /* tls.c */
 456 void *_rtld_tls_get_addr(void *, size_t, size_t);
 457 void _rtld_tls_initial_allocation(void);
 458 void *_rtld_tls_module_allocate(size_t index);
 459 int _rtld_tls_offset_allocate(Obj_Entry *);
 460 void _rtld_tls_offset_free(Obj_Entry *);
 461
 462 extern size_t _rtld_tls_dtv_generation;
 463 extern size_t _rtld_tls_max_index;
 464
 465 __dso_public extern void *__tls_get_addr(void *);
 466 #ifdef __i386__
 467 __dso_public extern void *___tls_get_addr(void *)
 468     __attribute__((__regparm__(1)));
 469 #endif
 470 #endif
 471
 472 /* map_object.c */
 473 struct stat;
 474 Obj_Entry *_rtld_map_object(const char *, int, const struct stat *);
 475 void _rtld_obj_free(Obj_Entry *);
 476 Obj_Entry *_rtld_obj_new(void);
 477
 478 #ifdef RTLD_LOADER
 479 /* function descriptors */
 480 #ifdef __HAVE_FUNCTION_DESCRIPTORS
 481 Elf_Addr _rtld_function_descriptor_alloc(const Obj_Entry *,
 482     const Elf_Sym *, Elf_Addr);
 483 const void *_rtld_function_descriptor_function(const void *);
 484
 485 void _rtld_call_function_void(const Obj_Entry *, Elf_Addr);
 486 Elf_Addr _rtld_call_function_addr(const Obj_Entry *, Elf_Addr);
 487 #else
 488 static inline void
 489 _rtld_call_function_void(const Obj_Entry *obj, Elf_Addr addr)
 490 {
 491         ((void (*)(void))addr)();
 492 }
 493 static inline Elf_Addr
 494 _rtld_call_function_addr(const Obj_Entry *obj, Elf_Addr addr)
 495 {
 496         return ((Elf_Addr(*)(void))addr)();
 497 }
 498 #endif /* __HAVE_FUNCTION_DESCRIPTORS */
 499 #endif /* RTLD_LOADER */
 500
 501 #endif /* _RTLD_SOURCE */
 502
 503 #endif /* RTLD_H */