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NetBSD/libexec/ld.elf_so/rtld.h

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/* $NetBSD: rtld.h,v 1.147 2023/07/30 09:20:14 riastradh Exp $ */
/*
* Copyright 1996 John D. Polstra.
* Copyright 1996 Matt Thomas <matt@3am-software.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by John Polstra.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef RTLD_H
#define RTLD_H
#include <dlfcn.h>
#include <signal.h>
#include <stdbool.h>
#include <stddef.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/queue.h>
#include <sys/exec_elf.h>
#include <sys/tls.h>
#include "rtldenv.h"
#include "link.h"
#if defined(_RTLD_SOURCE)
#if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__)
#include "unwind.h"
#endif
#ifndef RTLD_DEFAULT_LIBRARY_PATH
#define RTLD_DEFAULT_LIBRARY_PATH "/usr/lib"
#endif
#define _PATH_LD_HINTS "/etc/ld.so.conf"
extern size_t _rtld_pagesz;
#define round_down(x) ((x) & ~(_rtld_pagesz - 1))
#define round_up(x) round_down((x) + _rtld_pagesz - 1)
#define NEW(type) ((type *) xmalloc(sizeof(type)))
#define CNEW(type) ((type *) xcalloc(sizeof(type)))
/*
* Fill in a DoneList with an allocation large enough to hold all of
* the currently-loaded objects. Keep this in a macro since it calls
* alloca and we want that to occur within the scope of the caller.
*/
#define _rtld_donelist_init(dlp) \
((dlp)->num_alloc = _rtld_objcount, \
(dlp)->objs = alloca((dlp)->num_alloc * sizeof((dlp)->objs[0])), \
assert((dlp)->objs != NULL), \
(dlp)->num_used = 0)
typedef struct Struct_Elf_Hash {
unsigned long sysv;
unsigned long gnu;
} Elf_Hash;
#endif /* _RTLD_SOURCE */
/*
* C++ has mandated the use of the following keywords for its new boolean
* type. We might as well follow their lead.
*/
struct Struct_Obj_Entry;
typedef struct Struct_Objlist_Entry {
SIMPLEQ_ENTRY(Struct_Objlist_Entry) link;
struct Struct_Obj_Entry *obj;
} Objlist_Entry;
typedef SIMPLEQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
typedef struct Struct_Name_Entry {
SIMPLEQ_ENTRY(Struct_Name_Entry) link;
char name[1];
} Name_Entry;
typedef struct Struct_Needed_Entry {
struct Struct_Needed_Entry *next;
struct Struct_Obj_Entry *obj;
unsigned long name; /* Offset of name in string table */
} Needed_Entry;
typedef struct _rtld_search_path_t {
struct _rtld_search_path_t *sp_next;
const char *sp_path;
size_t sp_pathlen;
} Search_Path;
typedef struct Struct_Ver_Entry {
Elf_Word hash;
u_int flags;
const char *name;
const char *file;
} Ver_Entry;
/* Ver_Entry.flags */
#define VER_INFO_HIDDEN 0x01
#define RTLD_MAX_ENTRY 10
#define RTLD_MAX_LIBRARY 4
#define RTLD_MAX_CTL 2
typedef struct _rtld_library_xform_t {
struct _rtld_library_xform_t *next;
char *name;
const char *ctlname;
struct {
char *value;
char *library[RTLD_MAX_LIBRARY];
} entry[RTLD_MAX_ENTRY];
} Library_Xform;
/*
* Shared object descriptor.
*
* Items marked with "(%)" are dynamically allocated, and must be freed
* when the structure is destroyed.
*/
typedef void (*fptr_t)(void);
typedef struct Struct_Obj_Entry {
struct Struct_Obj_Entry *next;
char *path; /* Pathname of underlying file (%) */
int refcount;
int dl_refcount; /* Number of times loaded by dlopen */
/* These items are computed by map_object() or by digest_phdr(). */
caddr_t mapbase; /* Base address of mapped region */
size_t mapsize; /* Size of mapped region in bytes */
size_t textsize; /* Size of text segment in bytes */
Elf_Addr vaddrbase; /* Base address in shared object file */
caddr_t relocbase; /* Reloc const = mapbase - *vaddrbase */
Elf_Dyn *dynamic; /* Dynamic section */
caddr_t entry; /* Entry point */
const Elf_Phdr *phdr; /* Program header (may be xmalloc'ed) */
size_t phsize; /* Size of program header in bytes */
/* Items from the dynamic section. */
Elf_Addr *pltgot; /* PLTGOT table */
const Elf_Rel *rel; /* Relocation entries */
const Elf_Rel *rellim; /* Limit of Relocation entries */
const Elf_Rela *rela; /* Relocation entries */
const Elf_Rela *relalim; /* Limit of Relocation entries */
const Elf_Rel *pltrel; /* PLT relocation entries */
const Elf_Rel *pltrellim; /* Limit of PLT relocation entries */
const Elf_Rela *pltrela; /* PLT relocation entries */
const Elf_Rela *pltrelalim; /* Limit of PLT relocation entries */
const Elf_Sym *symtab; /* Symbol table */
const char *strtab; /* String table */
unsigned long strsize; /* Size in bytes of string table */
#if defined(__mips__) || defined(__riscv__)
Elf_Word local_gotno; /* Number of local GOT entries */
Elf_Word symtabno; /* Number of dynamic symbols */
Elf_Word gotsym; /* First dynamic symbol in GOT */
#endif
/* SysV Hash fields */
const Elf_Symindx *buckets; /* Hash table buckets array */
unsigned long unused1; /* Used to be nbuckets */
const Elf_Symindx *chains; /* Hash table chain array */
unsigned long nchains; /* Number of chains */
Search_Path *rpaths; /* Search path specified in object */
Needed_Entry *needed; /* Shared objects needed by this (%) */
fptr_t init; /* Initialization function to call */
fptr_t fini; /* Termination function to call */
u_int32_t mainprog:1, /* True if this is the main program */
rtld:1, /* True if this is the dynamic linker */
textrel:1, /* True if there are relocations to
* text seg */
symbolic:1, /* True if generated with
* "-Bsymbolic" */
printed:1, /* True if ldd has printed it */
isdynamic:1, /* True if this is a pure PIC object */
mainref:1, /* True if on _rtld_list_main */
globalref:1, /* True if on _rtld_list_global */
init_done:1, /* True if .init has been added */
init_called:1, /* True if .init function has been
* called */
fini_called:1, /* True if .fini function has been
* called */
z_now:1, /* True if object's symbols should be
bound immediately */
z_nodelete:1, /* True if object should never be
unloaded */
z_initfirst:1, /* True if object's .init/.fini take
* priority over others */
z_noopen:1, /* True if object should never be
dlopen'ed */
phdr_loaded:1, /* Phdr is loaded and doesn't need to
* be freed. */
#if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
tls_static:1, /* True if static TLS offset
* has been allocated */
tls_dynamic:1, /* True if any non-static DTV entry
* has been allocated */
#endif
ref_nodel:1, /* Refcount increased to prevent dlclose */
sysv_hash:1, /* SysV Hash available */
gnu_hash:1; /* GNU Hash available */
struct link_map linkmap; /* for the debugger */
/* These items are computed by map_object() or by digest_phdr(). */
const char *interp; /* Pathname of the interpreter, if any */
Objlist dldags; /* Object belongs to these dlopened DAGs (%) */
Objlist dagmembers; /* DAG has these members (%) */
dev_t dev; /* Object's filesystem's device */
ino_t ino; /* Object's inode number */
void *ehdr;
/* SysV Hash fields */
uint32_t nbuckets; /* Number of buckets */
uint32_t nbuckets_m; /* Precomputed for fast remainder */
uint8_t nbuckets_s1;
uint8_t nbuckets_s2;
/* GNU Hash fields */
const uint32_t *buckets_gnu; /* Hash table buckets array */
uint32_t nbuckets_gnu; /* Number of GNU hash buckets */
uint32_t nbuckets_m_gnu; /* Precomputed for fast remainder */
uint8_t nbuckets_s1_gnu;
uint8_t nbuckets_s2_gnu;
const uint32_t *chains_gnu; /* Hash table chain array */
#define nchains_gnu nchains /* Number of symbols, shared with SysV Hash */
const Elf_Addr *bloom_gnu;
uint32_t symndx_gnu; /* First accessible symbol on dynsym table */
uint32_t mask_bm_gnu; /* Bloom filter words - 1 (bitmask) */
uint32_t shift2_gnu; /* Bloom filter shift count */
size_t pathlen; /* Pathname length */
SIMPLEQ_HEAD(, Struct_Name_Entry) names; /* List of names for this
* object we know about. */
#ifdef __powerpc__
#ifdef _LP64
Elf_Addr glink; /* global linkage */
#else
Elf_Addr *gotptr; /* GOT table (secure-plt only) */
#endif
#endif
#if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
/* Thread Local Storage support for this module */
size_t tlsindex; /* Index in DTV */
void *tlsinit; /* Base address of TLS init block */
size_t tlsinitsize; /* Size of TLS init block */
size_t tlssize; /* Size of TLS block */
size_t tlsoffset; /* Offset in the static TLS block */
size_t tlsalign; /* Needed alignment for static TLS */
#endif
#ifdef GNU_RELRO
/* relocation readonly */
void *relro_page;
size_t relro_size;
#endif
/* symbol versioning */
const Elf_Verneed *verneed; /* Required versions. */
Elf_Word verneednum; /* Number of entries in verneed table */
const Elf_Verdef *verdef; /* Provided versions. */
Elf_Word verdefnum; /* Number of entries in verdef table */
const Elf_Versym *versyms; /* Symbol versions table */
Ver_Entry *vertab; /* Versions required/defined by this
* object */
int vertabnum; /* Number of entries in vertab */
/* init_array/fini_array */
fptr_t *init_array; /* start of init array */
size_t init_arraysz; /* # of entries in it */
fptr_t *fini_array; /* start of fini array */
size_t fini_arraysz; /* # of entries in it */
/* IRELATIVE relocations */
size_t ifunc_remaining;
#if \
defined(__aarch64__) || \
defined(__arm__) || \
defined(__i386__) || \
defined(__powerpc__) || \
defined(__sparc__) || \
defined(__x86_64__)
#define IFUNC_NONPLT
/* On SPARC, the PLT variant is called JMP_IREL and counted above. */
size_t ifunc_remaining_nonplt;
#endif
size_t cxa_refcount; /* For TLS destructors. */
#ifdef __ARM_EABI__
void *exidx_start;
size_t exidx_sz;
#endif
} Obj_Entry;
typedef struct Struct_DoneList {
const Obj_Entry **objs; /* Array of object pointers */
unsigned int num_alloc; /* Allocated size of the array */
unsigned int num_used; /* Number of array slots used */
} DoneList;
#if defined(_RTLD_SOURCE)
extern struct r_debug _rtld_debug;
extern Search_Path *_rtld_default_paths;
extern Obj_Entry *_rtld_objlist;
extern Obj_Entry **_rtld_objtail;
extern u_int _rtld_objcount;
extern u_int _rtld_objloads;
extern const uintptr_t _rtld_compat_obj[];
extern Obj_Entry *_rtld_objmain;
extern Obj_Entry _rtld_objself;
extern Search_Path *_rtld_paths;
extern Library_Xform *_rtld_xforms;
extern bool _rtld_trust;
extern Objlist _rtld_list_global;
extern Objlist _rtld_list_main;
extern Elf_Sym _rtld_sym_zero;
extern u_int _rtld_objgen;
#define RTLD_MODEMASK 0x3
/* Flags to be passed into _rtld_symlook_ family of functions. */
#define SYMLOOK_IN_PLT 0x01 /* Lookup for PLT symbol */
#define SYMLOOK_DLSYM 0x02 /* Return newest versioned symbol.
Used by dlsym. */
/* Flags for _rtld_load_object() and friends. */
#define _RTLD_GLOBAL 0x01 /* Add object to global DAG. */
#define _RTLD_MAIN 0x02
#define _RTLD_NOLOAD 0x04 /* dlopen() specified RTLD_NOLOAD. */
#define _RTLD_DLOPEN 0x08 /* Load_object() called from dlopen(). */
/* Preallocation for static TLS model */
#define RTLD_STATIC_TLS_RESERVATION 64
/* rtld.c */
__dso_public char *dlerror(void);
__dso_public void *dlopen(const char *, int);
__dso_public void *dlsym(void *, const char *);
__dso_public int dlclose(void *);
__dso_public int dladdr(const void *, Dl_info *);
__dso_public int dlinfo(void *, int, void *);
__dso_public int dl_iterate_phdr(int (*)(struct dl_phdr_info *, size_t, void *),
void *);
__dso_public void *_dlauxinfo(void) __pure;
__dso_public void __dl_cxa_refcount(void *addr, ssize_t delta);
__dso_public pid_t __locked_fork(int *);
#if defined(__ARM_EABI__) && !defined(__ARM_DWARF_EH__)
/*
* This is used by libgcc to find the start and length of the exception table
* associated with a PC.
*/
__dso_public _Unwind_Ptr __gnu_Unwind_Find_exidx(_Unwind_Ptr, int *);
#endif
/* These aren't exported */
void _rtld_error(const char *, ...) __printflike(1,2);
void _rtld_die(void) __dead;
void *_rtld_objmain_sym(const char *);
__dso_public void _rtld_debug_state(void) __noinline;
void _rtld_linkmap_add(Obj_Entry *);
void _rtld_linkmap_delete(Obj_Entry *);
void _rtld_objlist_push_head(Objlist *, Obj_Entry *);
void _rtld_objlist_push_tail(Objlist *, Obj_Entry *);
Objlist_Entry *_rtld_objlist_find(Objlist *, const Obj_Entry *);
void _rtld_ref_dag(Obj_Entry *);
void _rtld_shared_enter(void);
void _rtld_shared_exit(void);
void _rtld_exclusive_enter(sigset_t *);
void _rtld_exclusive_exit(sigset_t *);
int _rtld_relro(const Obj_Entry *, bool);
/* expand.c */
size_t _rtld_expand_path(char *, size_t, const char *, const char *,\
const char *);
/* headers.c */
void _rtld_digest_dynamic(const char *, Obj_Entry *);
Obj_Entry *_rtld_digest_phdr(const Elf_Phdr *, int, caddr_t);
/* load.c */
Obj_Entry *_rtld_load_object(const char *, int);
int _rtld_load_needed_objects(Obj_Entry *, int);
int _rtld_preload(const char *);
#define OBJ_ERR (Obj_Entry *)(-1)
/* path.c */
void _rtld_add_paths(const char *, Search_Path **, const char *);
void _rtld_process_hints(const char *, Search_Path **, Library_Xform **,
const char *);
int _rtld_sysctl(const char *, void *, size_t *);
/* reloc.c */
int _rtld_do_copy_relocations(const Obj_Entry *);
int _rtld_relocate_objects(Obj_Entry *, bool);
int _rtld_relocate_nonplt_objects(Obj_Entry *);
int _rtld_relocate_plt_lazy(Obj_Entry *);
int _rtld_relocate_plt_objects(const Obj_Entry *);
void _rtld_setup_pltgot(const Obj_Entry *);
Elf_Addr _rtld_resolve_ifunc(const Obj_Entry *, const Elf_Sym *);
Elf_Addr _rtld_resolve_ifunc2(const Obj_Entry *, Elf_Addr);
void _rtld_call_ifunc(Obj_Entry *, sigset_t *, u_int);
/* search.c */
Obj_Entry *_rtld_load_library(const char *, const Obj_Entry *, int);
/* symbol.c */
const Elf_Sym *_rtld_symlook_obj(const char *, Elf_Hash *,
const Obj_Entry *, u_int, const Ver_Entry *);
const Elf_Sym *_rtld_find_symdef(unsigned long, const Obj_Entry *,
const Obj_Entry **, u_int);
const Elf_Sym *_rtld_find_plt_symdef(unsigned long, const Obj_Entry *,
const Obj_Entry **, bool);
const Elf_Sym *_rtld_symlook_list(const char *, Elf_Hash *,
const Objlist *, const Obj_Entry **, u_int, const Ver_Entry *, DoneList *);
const Elf_Sym *_rtld_symlook_default(const char *, Elf_Hash *,
const Obj_Entry *, const Obj_Entry **, u_int, const Ver_Entry *);
const Elf_Sym *_rtld_symlook_needed(const char *, Elf_Hash *,
const Needed_Entry *, const Obj_Entry **, u_int, const Ver_Entry *,
DoneList *, DoneList *);
/* symver.c */
void _rtld_object_add_name(Obj_Entry *, const char *);
int _rtld_object_match_name(const Obj_Entry *, const char *);
int _rtld_verify_object_versions(Obj_Entry *);
static __inline const Ver_Entry *
_rtld_fetch_ventry(const Obj_Entry *obj, unsigned long symnum)
{
Elf_Half vernum;
if (obj->vertab) {
vernum = VER_NDX(obj->versyms[symnum].vs_vers);
if (vernum >= obj->vertabnum) {
_rtld_error("%s: symbol %s has wrong verneed value %d",
obj->path, &obj->strtab[symnum], vernum);
} else if (obj->vertab[vernum].hash) {
return &obj->vertab[vernum];
}
}
return NULL;
}
#if defined(__HAVE_TLS_VARIANT_I) || defined(__HAVE_TLS_VARIANT_II)
/* tls.c */
void *_rtld_tls_get_addr(void *, size_t, size_t);
void _rtld_tls_initial_allocation(void);
int _rtld_tls_offset_allocate(Obj_Entry *);
void _rtld_tls_offset_free(Obj_Entry *);
extern size_t _rtld_tls_dtv_generation;
extern size_t _rtld_tls_max_index;
__dso_public extern void *__tls_get_addr(void *);
#ifdef __i386__
__dso_public extern void *___tls_get_addr(void *)
__attribute__((__regparm__(1)));
#endif
#endif
/* map_object.c */
struct stat;
Obj_Entry *_rtld_map_object(const char *, int, const struct stat *);
void _rtld_obj_free(Obj_Entry *);
Obj_Entry *_rtld_obj_new(void);
#ifdef RTLD_LOADER
/* function descriptors */
#ifdef __HAVE_FUNCTION_DESCRIPTORS
Elf_Addr _rtld_function_descriptor_alloc(const Obj_Entry *,
const Elf_Sym *, Elf_Addr);
const void *_rtld_function_descriptor_function(const void *);
Elf_Addr _rtld_call_function_addr(const Obj_Entry *, Elf_Addr);
#else
static inline Elf_Addr
_rtld_call_function_addr(const Obj_Entry *obj, Elf_Addr addr)
{
return ((Elf_Addr(*)(void))addr)();
}
#endif /* __HAVE_FUNCTION_DESCRIPTORS */
#endif /* RTLD_LOADER */
#endif /* _RTLD_SOURCE */
#endif /* RTLD_H */
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