libexec/ld.elf_so/rtld.h

   1 /*      $NetBSD: rtld.h,v 1.110 2012/08/15 03:46:06 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 #ifndef RTLD_DEFAULT_LIBRARY_PATH
  52 #define RTLD_DEFAULT_LIBRARY_PATH       "/lib:/usr/lib:/libexec"
  53 #endif
  54 #define _PATH_LD_HINTS                  "/etc/ld.so.conf"
  55
  56 extern size_t _rtld_pagesz;
  57
  58 #define round_down(x)   ((x) & ~(_rtld_pagesz - 1))
  59 #define round_up(x)     round_down((x) + _rtld_pagesz - 1)
  60
  61 #define NEW(type)       ((type *) xmalloc(sizeof(type)))
  62 #define CNEW(type)      ((type *) xcalloc(sizeof(type)))
  63
  64 /*
  65  * Fill in a DoneList with an allocation large enough to hold all of
  66  * the currently-loaded objects. Keep this in a macro since it calls
  67  * alloca and we want that to occur within the scope of the caller.
  68  */
  69 #define _rtld_donelist_init(dlp)                                        \
  70     ((dlp)->num_alloc = _rtld_objcount,                                 \
  71     (dlp)->objs = alloca((dlp)->num_alloc * sizeof((dlp)->objs[0])),    \
  72     assert((dlp)->objs != NULL),                                        \
  73     (dlp)->num_used = 0)
  74
  75 #endif /* _RTLD_SOURCE */
  76
  77 /*
  78  * C++ has mandated the use of the following keywords for its new boolean
  79  * type.  We might as well follow their lead.
  80  */
  81 struct Struct_Obj_Entry;
  82
  83 typedef struct Struct_Objlist_Entry {
  84         SIMPLEQ_ENTRY(Struct_Objlist_Entry) link;
  85         struct Struct_Obj_Entry *obj;
  86 } Objlist_Entry;
  87
  88 typedef SIMPLEQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
  89
  90 typedef struct Struct_Name_Entry {
  91         STAILQ_ENTRY(Struct_Name_Entry) link;
  92         char    name[1];
  93 } Name_Entry;
  94
  95 typedef struct Struct_Needed_Entry {
  96         struct Struct_Needed_Entry *next;
  97         struct Struct_Obj_Entry *obj;
  98         unsigned long   name;   /* Offset of name in string table */
  99 } Needed_Entry;
 100
 101 typedef struct _rtld_search_path_t {
 102         struct _rtld_search_path_t *sp_next;
 103         const char     *sp_path;
 104         size_t          sp_pathlen;
 105 } Search_Path;
 106
 107 typedef struct Struct_Ver_Entry {
 108         Elf_Word        hash;
 109         u_int           flags;
 110         const char     *name;
 111         const char     *file;
 112 } Ver_Entry;
 113
 114 /* Ver_Entry.flags */
 115 #define VER_INFO_HIDDEN 0x01
 116
 117 #define RTLD_MAX_ENTRY 10
 118 #define RTLD_MAX_LIBRARY 4
 119 #define RTLD_MAX_CTL 2
 120 typedef struct _rtld_library_xform_t {
 121         struct _rtld_library_xform_t *next;
 122         char *name;
 123         const char *ctlname;
 124         struct {
 125                 char *value;
 126                 char *library[RTLD_MAX_LIBRARY];
 127         } entry[RTLD_MAX_ENTRY];
 128 } Library_Xform;
 129
 130 /*
 131  * Shared object descriptor.
 132  *
 133  * Items marked with "(%)" are dynamically allocated, and must be freed
 134  * when the structure is destroyed.
 135  *
 136  * The layout of this structure needs to be preserved because pre-2.0 binaries
 137  * hard-coded the location of dlopen() and friends.
 138  */
 139
 140 #define RTLD_MAGIC      0xd550b87a
 141 #define RTLD_VERSION    1
 142
 143 typedef void (*fptr_t)(void);
 144
 145 typedef struct Struct_Obj_Entry {
 146         Elf32_Word      magic;          /* Magic number (sanity check) */
 147         Elf32_Word      version;        /* Version number of struct format */
 148
 149         struct Struct_Obj_Entry *next;
 150         char           *path;           /* Pathname of underlying file (%) */
 151         int             refcount;
 152         int             dl_refcount;    /* Number of times loaded by dlopen */
 153
 154         /* These items are computed by map_object() or by digest_phdr(). */
 155         caddr_t         mapbase;        /* Base address of mapped region */
 156         size_t          mapsize;        /* Size of mapped region in bytes */
 157         size_t          textsize;       /* Size of text segment in bytes */
 158         Elf_Addr        vaddrbase;      /* Base address in shared object file */
 159         caddr_t         relocbase;      /* Reloc const = mapbase - *vaddrbase */
 160         Elf_Dyn        *dynamic;        /* Dynamic section */
 161         caddr_t         entry;          /* Entry point */
 162         const Elf_Phdr *phdr;           /* Program header (may be xmalloc'ed) */
 163         size_t          phsize;         /* Size of program header in bytes */
 164
 165         /* Items from the dynamic section. */
 166         Elf_Addr       *pltgot;         /* PLTGOT table */
 167         const Elf_Rel  *rel;            /* Relocation entries */
 168         const Elf_Rel  *rellim;         /* Limit of Relocation entries */
 169         const Elf_Rela *rela;           /* Relocation entries */
 170         const Elf_Rela *relalim;        /* Limit of Relocation entries */
 171         const Elf_Rel  *pltrel;         /* PLT relocation entries */
 172         const Elf_Rel  *pltrellim;      /* Limit of PLT relocation entries */
 173         const Elf_Rela *pltrela;        /* PLT relocation entries */
 174         const Elf_Rela *pltrelalim;     /* Limit of PLT relocation entries */
 175         const Elf_Sym  *symtab;         /* Symbol table */
 176         const char     *strtab;         /* String table */
 177         unsigned long   strsize;        /* Size in bytes of string table */
 178 #ifdef __mips__
 179         Elf_Word        local_gotno;    /* Number of local GOT entries */
 180         Elf_Word        symtabno;       /* Number of dynamic symbols */
 181         Elf_Word        gotsym;         /* First dynamic symbol in GOT */
 182 #endif
 183
 184         const Elf_Symindx *buckets;     /* Hash table buckets array */
 185         unsigned long   unused1;        /* Used to be nbuckets */
 186         const Elf_Symindx *chains;      /* Hash table chain array */
 187         unsigned long   nchains;        /* Number of chains */
 188
 189         Search_Path    *rpaths;         /* Search path specified in object */
 190         Needed_Entry   *needed;         /* Shared objects needed by this (%) */
 191
 192         fptr_t          init;           /* Initialization function to call */
 193         fptr_t          fini;           /* Termination function to call */
 194
 195         /*
 196          * BACKWARDS COMPAT Entry points for dlopen() and friends.
 197          *
 198          * DO NOT MOVE OR ADD TO THE LIST
 199          *
 200          */
 201         void           *(*dlopen)(const char *, int);
 202         void           *(*dlsym)(void *, const char *);
 203         char           *(*dlerror)(void);
 204         int             (*dlclose)(void *);
 205         int             (*dladdr)(const void *, Dl_info *);
 206
 207         u_int32_t       mainprog:1,     /* True if this is the main program */
 208                         rtld:1,         /* True if this is the dynamic linker */
 209                         textrel:1,      /* True if there are relocations to
 210                                          * text seg */
 211                         symbolic:1,     /* True if generated with
 212                                          * "-Bsymbolic" */
 213                         printed:1,      /* True if ldd has printed it */
 214                         isdynamic:1,    /* True if this is a pure PIC object */
 215                         mainref:1,      /* True if on _rtld_list_main */
 216                         globalref:1,    /* True if on _rtld_list_global */
 217                         init_done:1,    /* True if .init has been added */
 218                         init_called:1,  /* True if .init function has been
 219                                          * called */
 220                         fini_called:1,  /* True if .fini function has been
 221                                          * called */
 222                         z_now:1,        /* True if object's symbols should be
 223                                            bound immediately */
 224                         z_nodelete:1,   /* True if object should never be
 225                                            unloaded */
 226                         z_initfirst:1,  /* True if object's .init/.fini take
 227                                          * priority over others */
 228                         z_noopen:1,     /* True if object should never be
 229                                            dlopen'ed */
 230                         phdr_loaded:1,  /* Phdr is loaded and doesn't need to
 231                                          * be freed. */
 232 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
 233                         tls_done:1,     /* True if static TLS offset
 234                                          * has been allocated */
 235 #endif
 236                         ref_nodel:1;    /* Refcount increased to prevent dlclose */
 237
 238         struct link_map linkmap;        /* for GDB */
 239
 240         /* These items are computed by map_object() or by digest_phdr(). */
 241         const char     *interp; /* Pathname of the interpreter, if any */
 242         Objlist         dldags; /* Object belongs to these dlopened DAGs (%) */
 243         Objlist         dagmembers;     /* DAG has these members (%) */
 244         dev_t           dev;            /* Object's filesystem's device */
 245         ino_t           ino;            /* Object's inode number */
 246
 247         void            *ehdr;
 248
 249         uint32_t        nbuckets;       /* Number of buckets */
 250         uint32_t        nbuckets_m;     /* Precomputed for fast remainder */
 251         uint8_t         nbuckets_s1;
 252         uint8_t         nbuckets_s2;
 253         size_t          pathlen;        /* Pathname length */
 254         STAILQ_HEAD(, Struct_Name_Entry) names; /* List of names for this object we
 255                                                    know about. */
 256
 257 #ifdef __powerpc__
 258         Elf_Addr       *gotptr;         /* GOT table (secure-plt only) */
 259 #endif
 260
 261 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
 262         /* Thread Local Storage support for this module */
 263         size_t          tlsindex;       /* Index in DTV */
 264         void            *tlsinit;       /* Base address of TLS init block */
 265         size_t          tlsinitsize;    /* Size of TLS init block */
 266         size_t          tlssize;        /* Size of TLS block */
 267         size_t          tlsoffset;      /* Offset in the static TLS block */
 268         size_t          tlsalign;       /* Needed alignment for static TLS */
 269 #endif
 270
 271         /* symbol versioning */
 272         const Elf_Verneed *verneed;     /* Required versions. */
 273         Elf_Word        verneednum;     /* Number of entries in verneed table */
 274         const Elf_Verdef  *verdef;      /* Provided versions. */
 275         Elf_Word        verdefnum;      /* Number of entries in verdef table */
 276         const Elf_Versym *versyms;      /* Symbol versions table */
 277
 278         Ver_Entry       *vertab;        /* Versions required/defined by this
 279                                          * object */
 280         int             vertabnum;      /* Number of entries in vertab */
 281
 282         /* init_array/fini_array */
 283         fptr_t          *init_array;    /* start of init array */
 284         size_t          init_arraysz;   /* # of entries in it */
 285         fptr_t          *fini_array;    /* start of fini array */
 286         size_t          fini_arraysz;   /* # of entries in it */
 287 } Obj_Entry;
 288
 289 typedef struct Struct_DoneList {
 290         const Obj_Entry **objs;         /* Array of object pointers */
 291         unsigned int num_alloc;         /* Allocated size of the array */
 292         unsigned int num_used;          /* Number of array slots used */
 293 } DoneList;
 294
 295
 296 #if defined(_RTLD_SOURCE)
 297
 298 extern struct r_debug _rtld_debug;
 299 extern Search_Path *_rtld_default_paths;
 300 extern Obj_Entry *_rtld_objlist;
 301 extern Obj_Entry **_rtld_objtail;
 302 extern u_int _rtld_objcount;
 303 extern u_int _rtld_objloads;
 304 extern Obj_Entry *_rtld_objmain;
 305 extern Obj_Entry _rtld_objself;
 306 extern Search_Path *_rtld_paths;
 307 extern Library_Xform *_rtld_xforms;
 308 extern bool _rtld_trust;
 309 extern Objlist _rtld_list_global;
 310 extern Objlist _rtld_list_main;
 311 extern Elf_Sym _rtld_sym_zero;
 312
 313 #define RTLD_MODEMASK 0x3
 314
 315 /* Flags to be passed into _rtld_symlook_ family of functions. */
 316 #define SYMLOOK_IN_PLT  0x01    /* Lookup for PLT symbol */
 317 #define SYMLOOK_DLSYM   0x02    /* Return newes versioned symbol.
 318                                    Used by dlsym. */
 319
 320 /* Flags for _rtld_load_object() and friends. */
 321 #define _RTLD_GLOBAL    0x01    /* Add object to global DAG. */
 322 #define _RTLD_MAIN      0x02
 323 #define _RTLD_NOLOAD    0x04    /* dlopen() specified RTLD_NOLOAD. */
 324 #define _RTLD_DLOPEN    0x08    /* Load_object() called from dlopen(). */
 325
 326 /* Preallocation for static TLS model */
 327 #define RTLD_STATIC_TLS_RESERVATION     64
 328
 329 /* rtld.c */
 330
 331 /* We export these symbols using _rtld_symbol_lookup and is_exported. */
 332 __dso_public char *dlerror(void);
 333 __dso_public void *dlopen(const char *, int);
 334 __dso_public void *dlsym(void *, const char *);
 335 __dso_public int dlclose(void *);
 336 __dso_public int dladdr(const void *, Dl_info *);
 337 __dso_public int dlinfo(void *, int, void *);
 338 __dso_public int dl_iterate_phdr(int (*)(struct dl_phdr_info *, size_t, void *),
 339     void *);
 340
 341 __dso_public void *_dlauxinfo(void) __pure;
 342
 343 /* These aren't exported */
 344 void _rtld_error(const char *, ...)
 345      __attribute__((__format__(__printf__,1,2)));
 346 void _rtld_die(void) __attribute__((__noreturn__));
 347 void *_rtld_objmain_sym(const char *);
 348 __dso_public void _rtld_debug_state(void) __noinline;
 349 void _rtld_linkmap_add(Obj_Entry *);
 350 void _rtld_linkmap_delete(Obj_Entry *);
 351 void _rtld_objlist_push_head(Objlist *, Obj_Entry *);
 352 void _rtld_objlist_push_tail(Objlist *, Obj_Entry *);
 353 Objlist_Entry *_rtld_objlist_find(Objlist *, const Obj_Entry *);
 354 void _rtld_ref_dag(Obj_Entry *);
 355
 356 void _rtld_shared_enter(void);
 357 void _rtld_shared_exit(void);
 358 void _rtld_exclusive_enter(sigset_t *);
 359 void _rtld_exclusive_exit(sigset_t *);
 360
 361 /* expand.c */
 362 size_t _rtld_expand_path(char *, size_t, const char *, const char *,\
 363     const char *);
 364
 365 /* headers.c */
 366 void _rtld_digest_dynamic(const char *, Obj_Entry *);
 367 Obj_Entry *_rtld_digest_phdr(const Elf_Phdr *, int, caddr_t);
 368
 369 /* load.c */
 370 Obj_Entry *_rtld_load_object(const char *, int);
 371 int _rtld_load_needed_objects(Obj_Entry *, int);
 372 int _rtld_preload(const char *);
 373
 374 #define OBJ_ERR (Obj_Entry *)(-1)
 375 /* path.c */
 376 void _rtld_add_paths(const char *, Search_Path **, const char *);
 377 void _rtld_process_hints(const char *, Search_Path **, Library_Xform **,
 378     const char *);
 379 int _rtld_sysctl(const char *, void *, size_t *);
 380
 381 /* reloc.c */
 382 int _rtld_do_copy_relocations(const Obj_Entry *);
 383 int _rtld_relocate_objects(Obj_Entry *, bool);
 384 int _rtld_relocate_nonplt_objects(Obj_Entry *);
 385 int _rtld_relocate_plt_lazy(const Obj_Entry *);
 386 int _rtld_relocate_plt_objects(const Obj_Entry *);
 387 void _rtld_setup_pltgot(const Obj_Entry *);
 388
 389 /* search.c */
 390 Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int);
 391
 392 /* symbol.c */
 393 unsigned long _rtld_elf_hash(const char *);
 394 const Elf_Sym *_rtld_symlook_obj(const char *, unsigned long,
 395     const Obj_Entry *, u_int, const Ver_Entry *);
 396 const Elf_Sym *_rtld_find_symdef(unsigned long, const Obj_Entry *,
 397     const Obj_Entry **, u_int);
 398 const Elf_Sym *_rtld_find_plt_symdef(unsigned long, const Obj_Entry *,
 399     const Obj_Entry **, bool);
 400
 401 const Elf_Sym *_rtld_symlook_list(const char *, unsigned long,
 402     const Objlist *, const Obj_Entry **, u_int, const Ver_Entry *, DoneList *);
 403 const Elf_Sym *_rtld_symlook_default(const char *, unsigned long,
 404     const Obj_Entry *, const Obj_Entry **, u_int, const Ver_Entry *);
 405 const Elf_Sym *_rtld_symlook_needed(const char *, unsigned long,
 406     const Needed_Entry *, const Obj_Entry **, u_int, const Ver_Entry *,
 407     DoneList *, DoneList *);
 408 #ifdef COMBRELOC
 409 void _rtld_combreloc_reset(const Obj_Entry *);
 410 #endif
 411
 412 /* symver.c */
 413 int _rtld_object_match_name(const Obj_Entry *, const char *);
 414 int _rtld_verify_object_versions(Obj_Entry *);
 415
 416 static __inline const Ver_Entry *
 417 _rtld_fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
 418 {
 419         Elf_Half vernum;
 420
 421         if (obj->vertab) {
 422                 vernum = VER_NDX(obj->versyms[symnum].vs_vers);
 423                 if (vernum >= obj->vertabnum) {
 424                         _rtld_error("%s: symbol %s has wrong verneed value %d",
 425                             obj->path, &obj->strtab[symnum], vernum);
 426                 } else if (obj->vertab[vernum].hash) {
 427                         return &obj->vertab[vernum];
 428                 }
 429         }
 430         return NULL;
 431 }
 432
 433 #if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
 434 /* tls.c */
 435 void *_rtld_tls_get_addr(void *, size_t, size_t);
 436 void _rtld_tls_initial_allocation(void);
 437 void *_rtld_tls_module_allocate(size_t index);
 438 int _rtld_tls_offset_allocate(Obj_Entry *);
 439 void _rtld_tls_offset_free(Obj_Entry *);
 440
 441 extern size_t _rtld_tls_dtv_generation;
 442 extern size_t _rtld_tls_max_index;
 443
 444 __dso_public extern void *__tls_get_addr(void *);
 445 #ifdef __i386__
 446 __dso_public extern void *___tls_get_addr(void *)
 447     __attribute__((__regparm__(1)));
 448 #endif
 449 #endif
 450
 451 /* map_object.c */
 452 struct stat;
 453 Obj_Entry *_rtld_map_object(const char *, int, const struct stat *);
 454 void _rtld_obj_free(Obj_Entry *);
 455 Obj_Entry *_rtld_obj_new(void);
 456
 457 /* function descriptors */
 458 #ifdef __HAVE_FUNCTION_DESCRIPTORS
 459 Elf_Addr _rtld_function_descriptor_alloc(const Obj_Entry *,
 460     const Elf_Sym *, Elf_Addr);
 461 const void *_rtld_function_descriptor_function(const void *);
 462 #endif /* __HAVE_FUNCTION_DESCRIPTORS */
 463
 464 #endif /* _RTLD_SOURCE */
 465
 466 #endif /* RTLD_H */