libexec/ld.elf_so/rtld.h

   1 /*      $NetBSD: rtld.h,v 1.99 2011/01/16 15:56:37 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 <stdbool.h>
  39 #include <stddef.h>
  40 #include <sys/param.h>
  41 #include <sys/types.h>
  42 #include <sys/queue.h>
  43 #include <sys/exec_elf.h>
  44 #include "rtldenv.h"
  45 #include "link.h"
  46
  47 #if defined(_RTLD_SOURCE)
  48
  49 #ifndef RTLD_DEFAULT_LIBRARY_PATH
  50 #define RTLD_DEFAULT_LIBRARY_PATH       "/lib:/usr/lib:/libexec"
  51 #endif
  52 #define _PATH_LD_HINTS                  "/etc/ld.so.conf"
  53
  54 extern size_t _rtld_pagesz;
  55
  56 #define round_down(x)   ((x) & ~(_rtld_pagesz - 1))
  57 #define round_up(x)     round_down((x) + _rtld_pagesz - 1)
  58
  59 #define NEW(type)       ((type *) xmalloc(sizeof(type)))
  60 #define CNEW(type)      ((type *) xcalloc(sizeof(type)))
  61
  62 /*
  63  * Fill in a DoneList with an allocation large enough to hold all of
  64  * the currently-loaded objects. Keep this in a macro since it calls
  65  * alloca and we want that to occur within the scope of the caller.
  66  */
  67 #define _rtld_donelist_init(dlp)                                        \
  68     ((dlp)->num_alloc = _rtld_objcount,                                 \
  69     (dlp)->objs = alloca((dlp)->num_alloc * sizeof((dlp)->objs[0])),    \
  70     assert((dlp)->objs != NULL),                                        \
  71     (dlp)->num_used = 0)
  72
  73 #endif /* _RTLD_SOURCE */
  74
  75 /*
  76  * C++ has mandated the use of the following keywords for its new boolean
  77  * type.  We might as well follow their lead.
  78  */
  79 struct Struct_Obj_Entry;
  80
  81 typedef struct Struct_Objlist_Entry {
  82         SIMPLEQ_ENTRY(Struct_Objlist_Entry) link;
  83         struct Struct_Obj_Entry *obj;
  84 } Objlist_Entry;
  85
  86 typedef SIMPLEQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
  87
  88 typedef struct Struct_Name_Entry {
  89         STAILQ_ENTRY(Struct_Name_Entry) link;
  90         char    name[1];
  91 } Name_Entry;
  92
  93 typedef struct Struct_Needed_Entry {
  94         struct Struct_Needed_Entry *next;
  95         struct Struct_Obj_Entry *obj;
  96         unsigned long   name;   /* Offset of name in string table */
  97 } Needed_Entry;
  98
  99 typedef struct _rtld_search_path_t {
 100         struct _rtld_search_path_t *sp_next;
 101         const char     *sp_path;
 102         size_t          sp_pathlen;
 103 } Search_Path;
 104
 105
 106 #define RTLD_MAX_ENTRY 10
 107 #define RTLD_MAX_LIBRARY 4
 108 #define RTLD_MAX_CTL 2
 109 typedef struct _rtld_library_xform_t {
 110         struct _rtld_library_xform_t *next;
 111         char *name;
 112         const char *ctlname;
 113         struct {
 114                 char *value;
 115                 char *library[RTLD_MAX_LIBRARY];
 116         } entry[RTLD_MAX_ENTRY];
 117 } Library_Xform;
 118
 119 /*
 120  * Shared object descriptor.
 121  *
 122  * Items marked with "(%)" are dynamically allocated, and must be freed
 123  * when the structure is destroyed.
 124  *
 125  * The layout of this structure needs to be preserved because pre-2.0 binaries
 126  * hard-coded the location of dlopen() and friends.
 127  */
 128
 129 #define RTLD_MAGIC      0xd550b87a
 130 #define RTLD_VERSION    1
 131
 132 typedef struct Struct_Obj_Entry {
 133         Elf32_Word      magic;          /* Magic number (sanity check) */
 134         Elf32_Word      version;        /* Version number of struct format */
 135
 136         struct Struct_Obj_Entry *next;
 137         char           *path;           /* Pathname of underlying file (%) */
 138         int             refcount;
 139         int             dl_refcount;    /* Number of times loaded by dlopen */
 140
 141         /* These items are computed by map_object() or by digest_phdr(). */
 142         caddr_t         mapbase;        /* Base address of mapped region */
 143         size_t          mapsize;        /* Size of mapped region in bytes */
 144         size_t          textsize;       /* Size of text segment in bytes */
 145         Elf_Addr        vaddrbase;      /* Base address in shared object file */
 146         caddr_t         relocbase;      /* Reloc const = mapbase - *vaddrbase */
 147         Elf_Dyn        *dynamic;        /* Dynamic section */
 148         caddr_t         entry;          /* Entry point */
 149         const Elf_Phdr *phdr;           /* Program header (may be xmalloc'ed) */
 150         size_t          phsize;         /* Size of program header in bytes */
 151
 152         /* Items from the dynamic section. */
 153         Elf_Addr       *pltgot;         /* PLTGOT table */
 154         const Elf_Rel  *rel;            /* Relocation entries */
 155         const Elf_Rel  *rellim;         /* Limit of Relocation entries */
 156         const Elf_Rela *rela;           /* Relocation entries */
 157         const Elf_Rela *relalim;        /* Limit of Relocation entries */
 158         const Elf_Rel  *pltrel;         /* PLT relocation entries */
 159         const Elf_Rel  *pltrellim;      /* Limit of PLT relocation entries */
 160         const Elf_Rela *pltrela;        /* PLT relocation entries */
 161         const Elf_Rela *pltrelalim;     /* Limit of PLT relocation entries */
 162         const Elf_Sym  *symtab;         /* Symbol table */
 163         const char     *strtab;         /* String table */
 164         unsigned long   strsize;        /* Size in bytes of string table */
 165 #ifdef __mips__
 166         Elf_Word        local_gotno;    /* Number of local GOT entries */
 167         Elf_Word        symtabno;       /* Number of dynamic symbols */
 168         Elf_Word        gotsym;         /* First dynamic symbol in GOT */
 169 #endif
 170
 171         const Elf_Symindx *buckets;     /* Hash table buckets array */
 172         unsigned long   unused1;        /* Used to be nbuckets */
 173         const Elf_Symindx *chains;      /* Hash table chain array */
 174         unsigned long   nchains;        /* Number of chains */
 175
 176         Search_Path    *rpaths;         /* Search path specified in object */
 177         Needed_Entry   *needed;         /* Shared objects needed by this (%) */
 178
 179         void            (*init)(void);  /* Initialization function to call */
 180         void            (*fini)(void);  /* Termination function to call */
 181
 182         /* Entry points for dlopen() and friends. */
 183         void           *(*dlopen)(const char *, int);
 184         void           *(*dlsym)(void *, const char *);
 185         char           *(*dlerror)(void);
 186         int             (*dlclose)(void *);
 187         int             (*dladdr)(const void *, Dl_info *);
 188
 189         u_int32_t       mainprog:1,     /* True if this is the main program */
 190                         rtld:1,         /* True if this is the dynamic linker */
 191                         textrel:1,      /* True if there are relocations to
 192                                          * text seg */
 193                         symbolic:1,     /* True if generated with
 194                                          * "-Bsymbolic" */
 195                         printed:1,      /* True if ldd has printed it */
 196                         isdynamic:1,    /* True if this is a pure PIC object */
 197                         mainref:1,      /* True if on _rtld_list_main */
 198                         globalref:1,    /* True if on _rtld_list_global */
 199                         init_done:1,    /* True if .init has been added */
 200                         init_called:1,  /* True if .init function has been
 201                                          * called */
 202                         fini_called:1,  /* True if .fini function has been
 203                                          * called */
 204                         z_now:1,        /* True if object's symbols should be
 205                                            bound immediately */
 206                         z_nodelete:1,   /* True if object should never be
 207                                            unloaded */
 208                         z_initfirst:1,  /* True if object's .init/.fini take
 209                                          * priority over others */
 210                         z_noopen:1,     /* True if object should never be
 211                                            dlopen'ed */
 212                         phdr_loaded:1,  /* Phdr is loaded and doesn't need to
 213                                          * be freed. */
 214                         ref_nodel:1;    /* Refcount increased to prevent dlclose */
 215
 216         struct link_map linkmap;        /* for GDB */
 217
 218         /* These items are computed by map_object() or by digest_phdr(). */
 219         const char     *interp; /* Pathname of the interpreter, if any */
 220         Objlist         dldags; /* Object belongs to these dlopened DAGs (%) */
 221         Objlist         dagmembers;     /* DAG has these members (%) */
 222         dev_t           dev;            /* Object's filesystem's device */
 223         ino_t           ino;            /* Object's inode number */
 224
 225         void            *ehdr;
 226
 227         uint32_t        nbuckets;       /* Number of buckets */
 228         uint32_t        nbuckets_m;     /* Precomputed for fast remainder */
 229         uint8_t         nbuckets_s1;
 230         uint8_t         nbuckets_s2;
 231         size_t          pathlen;        /* Pathname length */
 232         STAILQ_HEAD(, Struct_Name_Entry) names; /* List of names for this object we
 233                                                    know about. */
 234 #ifdef __powerpc__
 235         Elf_Addr       *gotptr;         /* GOT table (secure-plt only) */
 236 #endif
 237 } Obj_Entry;
 238
 239 typedef struct Struct_DoneList {
 240         const Obj_Entry **objs;         /* Array of object pointers */
 241         unsigned int num_alloc;         /* Allocated size of the array */
 242         unsigned int num_used;          /* Number of array slots used */
 243 } DoneList;
 244
 245
 246 #if defined(_RTLD_SOURCE)
 247
 248 extern struct r_debug _rtld_debug;
 249 extern Search_Path *_rtld_default_paths;
 250 extern Obj_Entry *_rtld_objlist;
 251 extern Obj_Entry **_rtld_objtail;
 252 extern u_int _rtld_objcount;
 253 extern u_int _rtld_objloads;
 254 extern Obj_Entry *_rtld_objmain;
 255 extern Obj_Entry _rtld_objself;
 256 extern Search_Path *_rtld_paths;
 257 extern Library_Xform *_rtld_xforms;
 258 extern bool _rtld_trust;
 259 extern Objlist _rtld_list_global;
 260 extern Objlist _rtld_list_main;
 261 extern Elf_Sym _rtld_sym_zero;
 262
 263 #define RTLD_MODEMASK 0x3
 264
 265 /* Flags for _rtld_load_object() and friends. */
 266 #define _RTLD_GLOBAL    0x01    /* Add object to global DAG. */
 267 #define _RTLD_MAIN      0x02
 268 #define _RTLD_NOLOAD    0x04    /* dlopen() specified RTLD_NOLOAD. */
 269 #define _RTLD_DLOPEN    0x08    /* Load_object() called from dlopen(). */
 270
 271 /* rtld.c */
 272
 273 /* We export these symbols using _rtld_symbol_lookup and is_exported. */
 274 __dso_public char *dlerror(void);
 275 __dso_public void *dlopen(const char *, int);
 276 __dso_public void *dlsym(void *, const char *);
 277 __dso_public int dlclose(void *);
 278 __dso_public int dladdr(const void *, Dl_info *);
 279 __dso_public int dlinfo(void *, int, void *);
 280 __dso_public int dl_iterate_phdr(int (*)(struct dl_phdr_info *, size_t, void *),
 281     void *);
 282
 283 /* These aren't exported */
 284 void _rtld_error(const char *, ...)
 285      __attribute__((__format__(__printf__,1,2)));
 286 void _rtld_die(void) __attribute__((__noreturn__));
 287 void *_rtld_objmain_sym(const char *);
 288 void _rtld_debug_state(void);
 289 void _rtld_linkmap_add(Obj_Entry *);
 290 void _rtld_linkmap_delete(Obj_Entry *);
 291 void _rtld_objlist_push_head(Objlist *, Obj_Entry *);
 292 void _rtld_objlist_push_tail(Objlist *, Obj_Entry *);
 293 Objlist_Entry *_rtld_objlist_find(Objlist *, const Obj_Entry *);
 294 void _rtld_ref_dag(Obj_Entry *);
 295
 296 /* expand.c */
 297 size_t _rtld_expand_path(char *, size_t, const char *, const char *,\
 298     const char *);
 299
 300 /* headers.c */
 301 void _rtld_digest_dynamic(const char *, Obj_Entry *);
 302 Obj_Entry *_rtld_digest_phdr(const Elf_Phdr *, int, caddr_t);
 303
 304 /* load.c */
 305 Obj_Entry *_rtld_load_object(const char *, int);
 306 int _rtld_load_needed_objects(Obj_Entry *, int);
 307 int _rtld_preload(const char *);
 308
 309 #define OBJ_ERR (Obj_Entry *)(-1)
 310 /* path.c */
 311 void _rtld_add_paths(const char *, Search_Path **, const char *);
 312 void _rtld_process_hints(const char *, Search_Path **, Library_Xform **,
 313     const char *);
 314 int _rtld_sysctl(const char *, void *, size_t *);
 315
 316 /* reloc.c */
 317 int _rtld_do_copy_relocations(const Obj_Entry *);
 318 int _rtld_relocate_objects(Obj_Entry *, bool);
 319 int _rtld_relocate_nonplt_objects(Obj_Entry *);
 320 int _rtld_relocate_plt_lazy(const Obj_Entry *);
 321 int _rtld_relocate_plt_objects(const Obj_Entry *);
 322 void _rtld_setup_pltgot(const Obj_Entry *);
 323
 324 /* search.c */
 325 Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int);
 326
 327 /* symbol.c */
 328 unsigned long _rtld_elf_hash(const char *);
 329 const Elf_Sym *_rtld_symlook_obj(const char *, unsigned long,
 330     const Obj_Entry *, bool);
 331 const Elf_Sym *_rtld_find_symdef(unsigned long, const Obj_Entry *,
 332     const Obj_Entry **, bool);
 333 const Elf_Sym *_rtld_find_plt_symdef(unsigned long, const Obj_Entry *,
 334     const Obj_Entry **, bool);
 335
 336 const Elf_Sym *_rtld_symlook_list(const char *, unsigned long,
 337     const Objlist *, const Obj_Entry **, bool, DoneList *);
 338 const Elf_Sym *_rtld_symlook_default(const char *, unsigned long,
 339     const Obj_Entry *, const Obj_Entry **, bool);
 340 const Elf_Sym *_rtld_symlook_needed(const char *, unsigned long,
 341     const Needed_Entry *, const Obj_Entry **, bool,
 342     DoneList *, DoneList *);
 343 #ifdef COMBRELOC
 344 void _rtld_combreloc_reset(const Obj_Entry *);
 345 #endif
 346
 347 /* map_object.c */
 348 struct stat;
 349 Obj_Entry *_rtld_map_object(const char *, int, const struct stat *);
 350 void _rtld_obj_free(Obj_Entry *);
 351 Obj_Entry *_rtld_obj_new(void);
 352
 353 /* function descriptors */
 354 #ifdef __HAVE_FUNCTION_DESCRIPTORS
 355 Elf_Addr _rtld_function_descriptor_alloc(const Obj_Entry *,
 356     const Elf_Sym *, Elf_Addr);
 357 const void *_rtld_function_descriptor_function(const void *);
 358 #endif /* __HAVE_FUNCTION_DESCRIPTORS */
 359
 360 #endif /* _RTLD_SOURCE */
 361
 362 #endif /* RTLD_H */