libexec/rtld-elf/rtld.h

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause
   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
  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>
  37 #include <stdarg.h>
  38 #include <stdbool.h>
  39 #include <setjmp.h>
  40 #include <stddef.h>
  41
  42 #include "rtld_lock.h"
  43 #include "rtld_machdep.h"
  44
  45 #define NEW(type)       ((type *) xmalloc(sizeof(type)))
  46 #define CNEW(type)      ((type *) xcalloc(1, sizeof(type)))
  47
  48 extern size_t tls_last_offset;
  49 extern size_t tls_last_size;
  50 extern size_t tls_static_space;
  51 extern Elf_Addr tls_dtv_generation;
  52 extern int tls_max_index;
  53 extern size_t ld_static_tls_extra;
  54
  55 extern int npagesizes;
  56 extern size_t *pagesizes;
  57 extern size_t page_size;
  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     /* Items from the dynamic section. */
 169     Elf_Addr *pltgot;           /* PLT or GOT, depending on architecture */
 170     const Elf_Rel *rel;         /* Relocation entries */
 171     unsigned long relsize;      /* Size in bytes of relocation info */
 172     const Elf_Rela *rela;       /* Relocation entries with addend */
 173     unsigned long relasize;     /* Size in bytes of addend relocation info */
 174     const Elf_Relr *relr;       /* RELR relocation entries */
 175     unsigned long relrsize;     /* Size in bytes of RELR relocations */
 176     const Elf_Rel *pltrel;      /* PLT relocation entries */
 177     unsigned long pltrelsize;   /* Size in bytes of PLT relocation info */
 178     const Elf_Rela *pltrela;    /* PLT relocation entries with addend */
 179     unsigned long pltrelasize;  /* Size in bytes of PLT addend reloc info */
 180     const Elf_Sym *symtab;      /* Symbol table */
 181     const char *strtab;         /* String table */
 182     unsigned long strsize;      /* Size in bytes of string table */
 183
 184     const Elf_Verneed *verneed; /* Required versions. */
 185     Elf_Word verneednum;        /* Number of entries in verneed table */
 186     const Elf_Verdef  *verdef;  /* Provided versions. */
 187     Elf_Word verdefnum;         /* Number of entries in verdef table */
 188     const Elf_Versym *versyms;  /* Symbol versions table */
 189
 190     const Elf_Hashelt *buckets; /* Hash table buckets array */
 191     unsigned long nbuckets;     /* Number of buckets */
 192     const Elf_Hashelt *chains;  /* Hash table chain array */
 193     unsigned long nchains;      /* Number of entries in chain array */
 194
 195     Elf32_Word nbuckets_gnu;            /* Number of GNU hash buckets*/
 196     Elf32_Word symndx_gnu;              /* 1st accessible symbol on dynsym table */
 197     Elf32_Word maskwords_bm_gnu;        /* Bloom filter words - 1 (bitmask) */
 198     Elf32_Word shift2_gnu;              /* Bloom filter shift count */
 199     Elf32_Word dynsymcount;             /* Total entries in dynsym table */
 200     const Elf_Addr *bloom_gnu;          /* Bloom filter used by GNU hash func */
 201     const Elf_Hashelt *buckets_gnu;     /* GNU hash table bucket array */
 202     const Elf_Hashelt *chain_zero_gnu;  /* GNU hash table value array (Zeroed) */
 203
 204     const char *rpath;          /* Search path specified in object */
 205     const char *runpath;        /* Search path with different priority */
 206     Needed_Entry *needed;       /* Shared objects needed by this one (%) */
 207     Needed_Entry *needed_filtees;
 208     Needed_Entry *needed_aux_filtees;
 209
 210     STAILQ_HEAD(, Struct_Name_Entry) names; /* List of names for this object we
 211                                                know about. */
 212     Ver_Entry *vertab;          /* Versions required /defined by this object */
 213     int vernum;                 /* Number of entries in vertab */
 214
 215     Elf_Addr init;              /* Initialization function to call */
 216     Elf_Addr fini;              /* Termination function to call */
 217     Elf_Addr preinit_array;     /* Pre-initialization array of functions */
 218     Elf_Addr init_array;        /* Initialization array of functions */
 219     Elf_Addr fini_array;        /* Termination array of functions */
 220     int preinit_array_num;      /* Number of entries in preinit_array */
 221     int init_array_num;         /* Number of entries in init_array */
 222     int fini_array_num;         /* Number of entries in fini_array */
 223
 224     int32_t osrel;              /* OSREL note value */
 225     uint32_t fctl0;             /* FEATURE_CONTROL note desc[0] value */
 226
 227     bool mainprog : 1;          /* True if this is the main program */
 228     bool rtld : 1;              /* True if this is the dynamic linker */
 229     bool relocated : 1;         /* True if processed by relocate_objects() */
 230     bool ver_checked : 1;       /* True if processed by rtld_verify_object_versions */
 231     bool textrel : 1;           /* True if there are relocations to text seg */
 232     bool symbolic : 1;          /* True if generated with "-Bsymbolic" */
 233     bool deepbind : 1;          /* True if loaded with RTLD_DEEPBIND" */
 234     bool bind_now : 1;          /* True if all relocations should be made first */
 235     bool traced : 1;            /* Already printed in ldd trace output */
 236     bool jmpslots_done : 1;     /* Already have relocated the jump slots */
 237     bool init_done : 1;         /* Already have added object to init list */
 238     bool tls_static : 1;        /* Already allocated offset for static TLS */
 239     bool tls_dynamic : 1;       /* A non-static DTV entry has been allocated */
 240     bool phdr_alloc : 1;        /* Phdr is allocated and needs to be freed. */
 241     bool z_origin : 1;          /* Process rpath and soname tokens */
 242     bool z_nodelete : 1;        /* Do not unload the object and dependencies */
 243     bool z_noopen : 1;          /* Do not load on dlopen */
 244     bool z_loadfltr : 1;        /* Immediately load filtees */
 245     bool z_interpose : 1;       /* Interpose all objects but main */
 246     bool z_nodeflib : 1;        /* Don't search default library path */
 247     bool z_global : 1;          /* Make the object global */
 248     bool z_pie : 1;             /* Object proclaimed itself PIE executable */
 249     bool static_tls : 1;        /* Needs static TLS allocation */
 250     bool static_tls_copied : 1; /* Needs static TLS copying */
 251     bool ref_nodel : 1;         /* Refcount increased to prevent dlclose */
 252     bool init_scanned: 1;       /* Object is already on init list. */
 253     bool on_fini_list: 1;       /* Object is already on fini list. */
 254     bool dag_inited : 1;        /* Object has its DAG initialized. */
 255     bool filtees_loaded : 1;    /* Filtees loaded */
 256     bool filtees_loading : 1;   /* In process of filtees loading */
 257     bool irelative : 1;         /* Object has R_MACHDEP_IRELATIVE relocs */
 258     bool irelative_nonplt : 1;  /* Object has R_MACHDEP_IRELATIVE non-plt relocs */
 259     bool gnu_ifunc : 1;         /* Object has references to STT_GNU_IFUNC */
 260     bool non_plt_gnu_ifunc : 1; /* Object has non-plt IFUNC references */
 261     bool ifuncs_resolved : 1;   /* Object ifuncs were already resolved */
 262     bool crt_no_init : 1;       /* Object' crt does not call _init/_fini */
 263     bool valid_hash_sysv : 1;   /* A valid System V hash hash tag is available */
 264     bool valid_hash_gnu : 1;    /* A valid GNU hash tag is available */
 265     bool dlopened : 1;          /* dlopen()-ed (vs. load statically) */
 266     bool marker : 1;            /* marker on the global obj list */
 267     bool unholdfree : 1;        /* unmap upon last unhold */
 268     bool doomed : 1;            /* Object cannot be referenced */
 269
 270     MD_OBJ_ENTRY;
 271
 272     struct link_map linkmap;    /* For GDB and dlinfo() */
 273     Objlist dldags;             /* Object belongs to these dlopened DAGs (%) */
 274     Objlist dagmembers;         /* DAG has these members (%) */
 275     dev_t dev;                  /* Object's filesystem's device */
 276     ino_t ino;                  /* Object's inode number */
 277     void *priv;                 /* Platform-dependent */
 278 } Obj_Entry;
 279
 280 #define RTLD_MAGIC      0xd550b87a
 281 #define RTLD_VERSION    1
 282
 283 TAILQ_HEAD(obj_entry_q, Struct_Obj_Entry);
 284
 285 #define RTLD_STATIC_TLS_EXTRA   128
 286
 287 /* Flags to be passed into symlook_ family of functions. */
 288 #define SYMLOOK_IN_PLT  0x01    /* Lookup for PLT symbol */
 289 #define SYMLOOK_DLSYM   0x02    /* Return newest versioned symbol. Used by
 290                                    dlsym. */
 291 #define SYMLOOK_EARLY   0x04    /* Symlook is done during initialization. */
 292 #define SYMLOOK_IFUNC   0x08    /* Allow IFUNC processing in
 293                                    reloc_non_plt(). */
 294
 295 /* Flags for load_object(). */
 296 #define RTLD_LO_NOLOAD  0x01    /* dlopen() specified RTLD_NOLOAD. */
 297 #define RTLD_LO_DLOPEN  0x02    /* Load_object() called from dlopen(). */
 298 #define RTLD_LO_TRACE   0x04    /* Only tracing. */
 299 #define RTLD_LO_NODELETE 0x08   /* Loaded object cannot be closed. */
 300 #define RTLD_LO_FILTEES 0x10    /* Loading filtee. */
 301 #define RTLD_LO_EARLY   0x20    /* Do not call ctors, postpone it to the
 302                                    initialization during the image start. */
 303 #define RTLD_LO_IGNSTLS 0x40    /* Do not allocate static TLS */
 304 #define RTLD_LO_DEEPBIND 0x80   /* Force symbolic for this object */
 305
 306 /*
 307  * Symbol cache entry used during relocation to avoid multiple lookups
 308  * of the same symbol.
 309  */
 310 typedef struct Struct_SymCache {
 311     const Elf_Sym *sym;         /* Symbol table entry */
 312     const Obj_Entry *obj;       /* Shared object which defines it */
 313 } SymCache;
 314
 315 /*
 316  * This structure provides a reentrant way to keep a list of objects and
 317  * check which ones have already been processed in some way.
 318  */
 319 typedef struct Struct_DoneList {
 320     const Obj_Entry **objs;             /* Array of object pointers */
 321     unsigned int num_alloc;             /* Allocated size of the array */
 322     unsigned int num_used;              /* Number of array slots used */
 323 } DoneList;
 324
 325 struct Struct_RtldLockState {
 326         int lockstate;
 327         sigjmp_buf env;
 328 };
 329
 330 struct fill_search_info_args {
 331         int request;
 332         unsigned int flags;
 333         struct dl_serinfo *serinfo;
 334         struct dl_serpath *serpath;
 335         char *strspace;
 336 };
 337
 338 /*
 339  * The pack of arguments and results for the symbol lookup functions.
 340  */
 341 typedef struct Struct_SymLook {
 342     const char *name;
 343     unsigned long hash;
 344     uint32_t hash_gnu;
 345     const Ver_Entry *ventry;
 346     int flags;
 347     const Obj_Entry *defobj_out;
 348     const Elf_Sym *sym_out;
 349     struct Struct_RtldLockState *lockstate;
 350 } SymLook;
 351
 352 enum {
 353         LD_BIND_NOW = 0,
 354         LD_PRELOAD,
 355         LD_LIBMAP,
 356         LD_LIBRARY_PATH,
 357         LD_LIBRARY_PATH_FDS,
 358         LD_LIBMAP_DISABLE,
 359         LD_BIND_NOT,
 360         LD_DEBUG,
 361         LD_ELF_HINTS_PATH,
 362         LD_LOADFLTR,
 363         LD_LIBRARY_PATH_RPATH,
 364         LD_PRELOAD_FDS,
 365         LD_DYNAMIC_WEAK,
 366         LD_TRACE_LOADED_OBJECTS,
 367         LD_UTRACE,
 368         LD_DUMP_REL_PRE,
 369         LD_DUMP_REL_POST,
 370         LD_TRACE_LOADED_OBJECTS_PROGNAME,
 371         LD_TRACE_LOADED_OBJECTS_FMT1,
 372         LD_TRACE_LOADED_OBJECTS_FMT2,
 373         LD_TRACE_LOADED_OBJECTS_ALL,
 374         LD_SHOW_AUXV,
 375         LD_STATIC_TLS_EXTRA,
 376         LD_NO_DL_ITERATE_PHDR_AFTER_FORK,
 377 };
 378
 379 void _rtld_error(const char *, ...) __printflike(1, 2) __exported;
 380 void rtld_die(void) __dead2;
 381 const char *rtld_strerror(int);
 382 Obj_Entry *map_object(int, const char *, const struct stat *);
 383 void *xcalloc(size_t, size_t);
 384 void *xmalloc(size_t);
 385 char *xstrdup(const char *);
 386 void *xmalloc_aligned(size_t size, size_t align, size_t offset);
 387 extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
 388 extern Elf_Sym sym_zero;        /* For resolving undefined weak refs. */
 389 extern bool ld_bind_not;
 390 extern bool ld_fast_sigblock;
 391
 392 void dump_relocations(Obj_Entry *);
 393 void dump_obj_relocations(Obj_Entry *);
 394 void dump_Elf_Rel(Obj_Entry *, const Elf_Rel *, u_long);
 395 void dump_Elf_Rela(Obj_Entry *, const Elf_Rela *, u_long);
 396
 397 /*
 398  * Function declarations.
 399  */
 400 const char *ld_get_env_var(int idx);
 401 uintptr_t rtld_round_page(uintptr_t);
 402 uintptr_t rtld_trunc_page(uintptr_t);
 403 Elf32_Word elf_hash(const char *);
 404 const Elf_Sym *find_symdef(unsigned long, const Obj_Entry *,
 405   const Obj_Entry **, int, SymCache *, struct Struct_RtldLockState *);
 406 void lockdflt_init(void);
 407 void digest_notes(Obj_Entry *, Elf_Addr, Elf_Addr);
 408 Obj_Entry *globallist_curr(const Obj_Entry *obj);
 409 Obj_Entry *globallist_next(const Obj_Entry *obj);
 410 void obj_free(Obj_Entry *);
 411 Obj_Entry *obj_new(void);
 412 Obj_Entry *obj_from_addr(const void *);
 413 void _rtld_bind_start(void);
 414 void *rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def);
 415 void symlook_init(SymLook *, const char *);
 416 int symlook_obj(SymLook *, const Obj_Entry *);
 417 void *tls_get_addr_common(uintptr_t **dtvp, int index, size_t offset);
 418 void *allocate_tls(Obj_Entry *, void *, size_t, size_t);
 419 void free_tls(void *, size_t, size_t);
 420 void *allocate_module_tls(int index);
 421 bool allocate_tls_offset(Obj_Entry *obj);
 422 void free_tls_offset(Obj_Entry *obj);
 423 const Ver_Entry *fetch_ventry(const Obj_Entry *obj, unsigned long);
 424 int convert_prot(int elfflags);
 425 bool check_elf_headers(const Elf_Ehdr *hdr, const char *path);
 426
 427 /*
 428  * MD function declarations.
 429  */
 430 int do_copy_relocations(Obj_Entry *);
 431 int reloc_non_plt(Obj_Entry *, Obj_Entry *, int flags,
 432     struct Struct_RtldLockState *);
 433 int reloc_plt(Obj_Entry *, int flags, struct Struct_RtldLockState *);
 434 int reloc_jmpslots(Obj_Entry *, int flags, struct Struct_RtldLockState *);
 435 int reloc_iresolve(Obj_Entry *, struct Struct_RtldLockState *);
 436 int reloc_iresolve_nonplt(Obj_Entry *, struct Struct_RtldLockState *);
 437 int reloc_gnu_ifunc(Obj_Entry *, int flags, struct Struct_RtldLockState *);
 438 void ifunc_init(Elf_Auxinfo *[__min_size(AT_COUNT)]);
 439 void init_pltgot(Obj_Entry *);
 440 void allocate_initial_tls(Obj_Entry *);
 441
 442 #endif /* } */