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/*-
* Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
* Copyright 2003 Alexander Kabaev <kan@FreeBSD.ORG>.
* Copyright 2009-2012 Konstantin Belousov <kib@FreeBSD.ORG>.
* Copyright 2012 John Marino <draco@marino.st>.
* 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.
*
* 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.
*
* $FreeBSD$
*/
/*
* Dynamic linker for ELF.
*
* John Polstra <jdp@polstra.com>.
*/
#ifndef __GNUC__
#error "GCC is needed to compile this file"
#endif
#include <sys/param.h>
#include <sys/mount.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/uio.h>
#include <sys/utsname.h>
#include <sys/ktrace.h>
#include <dlfcn.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "debug.h"
#include "rtld.h"
#include "libmap.h"
#include "rtld_tls.h"
#include "rtld_printf.h"
#include "notes.h"
#ifndef COMPAT_32BIT
#define PATH_RTLD "/libexec/ld-elf.so.1"
#else
#define PATH_RTLD "/libexec/ld-elf32.so.1"
#endif
/* Types. */
typedef void (*func_ptr_type)();
typedef void * (*path_enum_proc) (const char *path, size_t len, void *arg);
/*
* Function declarations.
*/
static const char *basename(const char *);
static void die(void) __dead2;
static void digest_dynamic1(Obj_Entry *, int, const Elf_Dyn **,
const Elf_Dyn **, const Elf_Dyn **);
static void digest_dynamic2(Obj_Entry *, const Elf_Dyn *, const Elf_Dyn *,
const Elf_Dyn *);
static void digest_dynamic(Obj_Entry *, int);
static Obj_Entry *digest_phdr(const Elf_Phdr *, int, caddr_t, const char *);
static Obj_Entry *dlcheck(void *);
static Obj_Entry *dlopen_object(const char *name, int fd, Obj_Entry *refobj,
int lo_flags, int mode, RtldLockState *lockstate);
static Obj_Entry *do_load_object(int, const char *, char *, struct stat *, int);
static int do_search_info(const Obj_Entry *obj, int, struct dl_serinfo *);
static bool donelist_check(DoneList *, const Obj_Entry *);
static void errmsg_restore(char *);
static char *errmsg_save(void);
static void *fill_search_info(const char *, size_t, void *);
static char *find_library(const char *, const Obj_Entry *);
static const char *gethints(bool);
static void init_dag(Obj_Entry *);
static void init_rtld(caddr_t, Elf_Auxinfo **);
static void initlist_add_neededs(Needed_Entry *, Objlist *);
static void initlist_add_objects(Obj_Entry *, Obj_Entry **, Objlist *);
static void linkmap_add(Obj_Entry *);
static void linkmap_delete(Obj_Entry *);
static void load_filtees(Obj_Entry *, int flags, RtldLockState *);
static void unload_filtees(Obj_Entry *);
static int load_needed_objects(Obj_Entry *, int);
static int load_preload_objects(void);
static Obj_Entry *load_object(const char *, int fd, const Obj_Entry *, int);
static void map_stacks_exec(RtldLockState *);
static Obj_Entry *obj_from_addr(const void *);
static void objlist_call_fini(Objlist *, Obj_Entry *, RtldLockState *);
static void objlist_call_init(Objlist *, RtldLockState *);
static void objlist_clear(Objlist *);
static Objlist_Entry *objlist_find(Objlist *, const Obj_Entry *);
static void objlist_init(Objlist *);
static void objlist_push_head(Objlist *, Obj_Entry *);
static void objlist_push_tail(Objlist *, Obj_Entry *);
static void objlist_put_after(Objlist *, Obj_Entry *, Obj_Entry *);
static void objlist_remove(Objlist *, Obj_Entry *);
static void *path_enumerate(const char *, path_enum_proc, void *);
static int relocate_object_dag(Obj_Entry *root, bool bind_now,
Obj_Entry *rtldobj, int flags, RtldLockState *lockstate);
static int relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj,
int flags, RtldLockState *lockstate);
static int relocate_objects(Obj_Entry *, bool, Obj_Entry *, int,
RtldLockState *);
static int resolve_objects_ifunc(Obj_Entry *first, bool bind_now,
int flags, RtldLockState *lockstate);
static int rtld_dirname(const char *, char *);
static int rtld_dirname_abs(const char *, char *);
static void *rtld_dlopen(const char *name, int fd, int mode);
static void rtld_exit(void);
static char *search_library_path(const char *, const char *);
static const void **get_program_var_addr(const char *, RtldLockState *);
static void set_program_var(const char *, const void *);
static int symlook_default(SymLook *, const Obj_Entry *refobj);
static int symlook_global(SymLook *, DoneList *);
static void symlook_init_from_req(SymLook *, const SymLook *);
static int symlook_list(SymLook *, const Objlist *, DoneList *);
static int symlook_needed(SymLook *, const Needed_Entry *, DoneList *);
static int symlook_obj1_sysv(SymLook *, const Obj_Entry *);
static int symlook_obj1_gnu(SymLook *, const Obj_Entry *);
static void trace_loaded_objects(Obj_Entry *);
static void unlink_object(Obj_Entry *);
static void unload_object(Obj_Entry *);
static void unref_dag(Obj_Entry *);
static void ref_dag(Obj_Entry *);
static char *origin_subst_one(char *, const char *, const char *, bool);
static char *origin_subst(char *, const char *);
static void preinit_main(void);
static int rtld_verify_versions(const Objlist *);
static int rtld_verify_object_versions(Obj_Entry *);
static void object_add_name(Obj_Entry *, const char *);
static int object_match_name(const Obj_Entry *, const char *);
static void ld_utrace_log(int, void *, void *, size_t, int, const char *);
static void rtld_fill_dl_phdr_info(const Obj_Entry *obj,
struct dl_phdr_info *phdr_info);
static uint32_t gnu_hash(const char *);
static bool matched_symbol(SymLook *, const Obj_Entry *, Sym_Match_Result *,
const unsigned long);
void r_debug_state(struct r_debug *, struct link_map *) __noinline;
/*
* Data declarations.
*/
static char *error_message; /* Message for dlerror(), or NULL */
struct r_debug r_debug; /* for GDB; */
static bool libmap_disable; /* Disable libmap */
static bool ld_loadfltr; /* Immediate filters processing */
static char *libmap_override; /* Maps to use in addition to libmap.conf */
static bool trust; /* False for setuid and setgid programs */
static bool dangerous_ld_env; /* True if environment variables have been
used to affect the libraries loaded */
static char *ld_bind_now; /* Environment variable for immediate binding */
static char *ld_debug; /* Environment variable for debugging */
static char *ld_library_path; /* Environment variable for search path */
static char *ld_preload; /* Environment variable for libraries to
load first */
static char *ld_elf_hints_path; /* Environment variable for alternative hints path */
static char *ld_tracing; /* Called from ldd to print libs */
static char *ld_utrace; /* Use utrace() to log events. */
static Obj_Entry *obj_list; /* Head of linked list of shared objects */
static Obj_Entry **obj_tail; /* Link field of last object in list */
static Obj_Entry *obj_main; /* The main program shared object */
static Obj_Entry obj_rtld; /* The dynamic linker shared object */
static unsigned int obj_count; /* Number of objects in obj_list */
static unsigned int obj_loads; /* Number of objects in obj_list */
static Objlist list_global = /* Objects dlopened with RTLD_GLOBAL */
STAILQ_HEAD_INITIALIZER(list_global);
static Objlist list_main = /* Objects loaded at program startup */
STAILQ_HEAD_INITIALIZER(list_main);
static Objlist list_fini = /* Objects needing fini() calls */
STAILQ_HEAD_INITIALIZER(list_fini);
Elf_Sym sym_zero; /* For resolving undefined weak refs. */
#define GDB_STATE(s,m) r_debug.r_state = s; r_debug_state(&r_debug,m);
extern Elf_Dyn _DYNAMIC;
#pragma weak _DYNAMIC
#ifndef RTLD_IS_DYNAMIC
#define RTLD_IS_DYNAMIC() (&_DYNAMIC != NULL)
#endif
int osreldate, pagesize;
long __stack_chk_guard[8] = {0, 0, 0, 0, 0, 0, 0, 0};
static int stack_prot = PROT_READ | PROT_WRITE | RTLD_DEFAULT_STACK_EXEC;
static int max_stack_flags;
/*
* Global declarations normally provided by crt1. The dynamic linker is
* not built with crt1, so we have to provide them ourselves.
*/
char *__progname;
char **environ;
/*
* Used to pass argc, argv to init functions.
*/
int main_argc;
char **main_argv;
/*
* Globals to control TLS allocation.
*/
size_t tls_last_offset; /* Static TLS offset of last module */
size_t tls_last_size; /* Static TLS size of last module */
size_t tls_static_space; /* Static TLS space allocated */
int tls_dtv_generation = 1; /* Used to detect when dtv size changes */
int tls_max_index = 1; /* Largest module index allocated */
bool ld_library_path_rpath = false;
/*
* Fill in a DoneList with an allocation large enough to hold all of
* the currently-loaded objects. Keep this as a macro since it calls
* alloca and we want that to occur within the scope of the caller.
*/
#define donelist_init(dlp) \
((dlp)->objs = alloca(obj_count * sizeof (dlp)->objs[0]), \
assert((dlp)->objs != NULL), \
(dlp)->num_alloc = obj_count, \
(dlp)->num_used = 0)
#define UTRACE_DLOPEN_START 1
#define UTRACE_DLOPEN_STOP 2
#define UTRACE_DLCLOSE_START 3
#define UTRACE_DLCLOSE_STOP 4
#define UTRACE_LOAD_OBJECT 5
#define UTRACE_UNLOAD_OBJECT 6
#define UTRACE_ADD_RUNDEP 7
#define UTRACE_PRELOAD_FINISHED 8
#define UTRACE_INIT_CALL 9
#define UTRACE_FINI_CALL 10
struct utrace_rtld {
char sig[4]; /* 'RTLD' */
int event;
void *handle;
void *mapbase; /* Used for 'parent' and 'init/fini' */
size_t mapsize;
int refcnt; /* Used for 'mode' */
char name[MAXPATHLEN];
};
#define LD_UTRACE(e, h, mb, ms, r, n) do { \
if (ld_utrace != NULL) \
ld_utrace_log(e, h, mb, ms, r, n); \
} while (0)
static void
ld_utrace_log(int event, void *handle, void *mapbase, size_t mapsize,
int refcnt, const char *name)
{
struct utrace_rtld ut;
ut.sig[0] = 'R';
ut.sig[1] = 'T';
ut.sig[2] = 'L';
ut.sig[3] = 'D';
ut.event = event;
ut.handle = handle;
ut.mapbase = mapbase;
ut.mapsize = mapsize;
ut.refcnt = refcnt;
bzero(ut.name, sizeof(ut.name));
if (name)
strlcpy(ut.name, name, sizeof(ut.name));
utrace(&ut, sizeof(ut));
}
/*
* Main entry point for dynamic linking. The first argument is the
* stack pointer. The stack is expected to be laid out as described
* in the SVR4 ABI specification, Intel 386 Processor Supplement.
* Specifically, the stack pointer points to a word containing
* ARGC. Following that in the stack is a null-terminated sequence
* of pointers to argument strings. Then comes a null-terminated
* sequence of pointers to environment strings. Finally, there is a
* sequence of "auxiliary vector" entries.
*
* The second argument points to a place to store the dynamic linker's
* exit procedure pointer and the third to a place to store the main
* program's object.
*
* The return value is the main program's entry point.
*/
func_ptr_type
_rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
{
Elf_Auxinfo *aux_info[AT_COUNT];
int i;
int argc;
char **argv;
char **env;
Elf_Auxinfo *aux;
Elf_Auxinfo *auxp;
const char *argv0;
Objlist_Entry *entry;
Obj_Entry *obj;
Obj_Entry **preload_tail;
Obj_Entry *last_interposer;
Objlist initlist;
RtldLockState lockstate;
char *library_path_rpath;
int mib[2];
size_t len;
/*
* On entry, the dynamic linker itself has not been relocated yet.
* Be very careful not to reference any global data until after
* init_rtld has returned. It is OK to reference file-scope statics
* and string constants, and to call static and global functions.
*/
/* Find the auxiliary vector on the stack. */
argc = *sp++;
argv = (char **) sp;
sp += argc + 1; /* Skip over arguments and NULL terminator */
env = (char **) sp;
while (*sp++ != 0) /* Skip over environment, and NULL terminator */
;
aux = (Elf_Auxinfo *) sp;
/* Digest the auxiliary vector. */
for (i = 0; i < AT_COUNT; i++)
aux_info[i] = NULL;
for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
if (auxp->a_type < AT_COUNT)
aux_info[auxp->a_type] = auxp;
}
/* Initialize and relocate ourselves. */
assert(aux_info[AT_BASE] != NULL);
init_rtld((caddr_t) aux_info[AT_BASE]->a_un.a_ptr, aux_info);
__progname = obj_rtld.path;
argv0 = argv[0] != NULL ? argv[0] : "(null)";
environ = env;
main_argc = argc;
main_argv = argv;
if (aux_info[AT_CANARY] != NULL &&
aux_info[AT_CANARY]->a_un.a_ptr != NULL) {
i = aux_info[AT_CANARYLEN]->a_un.a_val;
if (i > sizeof(__stack_chk_guard))
i = sizeof(__stack_chk_guard);
memcpy(__stack_chk_guard, aux_info[AT_CANARY]->a_un.a_ptr, i);
} else {
mib[0] = CTL_KERN;
mib[1] = KERN_ARND;
len = sizeof(__stack_chk_guard);
if (sysctl(mib, 2, __stack_chk_guard, &len, NULL, 0) == -1 ||
len != sizeof(__stack_chk_guard)) {
/* If sysctl was unsuccessful, use the "terminator canary". */
((unsigned char *)(void *)__stack_chk_guard)[0] = 0;
((unsigned char *)(void *)__stack_chk_guard)[1] = 0;
((unsigned char *)(void *)__stack_chk_guard)[2] = '\n';
((unsigned char *)(void *)__stack_chk_guard)[3] = 255;
}
}
trust = !issetugid();
ld_bind_now = getenv(LD_ "BIND_NOW");
/*
* If the process is tainted, then we un-set the dangerous environment
* variables. The process will be marked as tainted until setuid(2)
* is called. If any child process calls setuid(2) we do not want any
* future processes to honor the potentially un-safe variables.
*/
if (!trust) {
if (unsetenv(LD_ "PRELOAD") || unsetenv(LD_ "LIBMAP") ||
unsetenv(LD_ "LIBRARY_PATH") || unsetenv(LD_ "LIBMAP_DISABLE") ||
unsetenv(LD_ "DEBUG") || unsetenv(LD_ "ELF_HINTS_PATH") ||
unsetenv(LD_ "LOADFLTR") || unsetenv(LD_ "LIBRARY_PATH_RPATH")) {
_rtld_error("environment corrupt; aborting");
die();
}
}
ld_debug = getenv(LD_ "DEBUG");
libmap_disable = getenv(LD_ "LIBMAP_DISABLE") != NULL;
libmap_override = getenv(LD_ "LIBMAP");
ld_library_path = getenv(LD_ "LIBRARY_PATH");
ld_preload = getenv(LD_ "PRELOAD");
ld_elf_hints_path = getenv(LD_ "ELF_HINTS_PATH");
ld_loadfltr = getenv(LD_ "LOADFLTR") != NULL;
library_path_rpath = getenv(LD_ "LIBRARY_PATH_RPATH");
if (library_path_rpath != NULL) {
if (library_path_rpath[0] == 'y' ||
library_path_rpath[0] == 'Y' ||
library_path_rpath[0] == '1')
ld_library_path_rpath = true;
else
ld_library_path_rpath = false;
}
dangerous_ld_env = libmap_disable || (libmap_override != NULL) ||
(ld_library_path != NULL) || (ld_preload != NULL) ||
(ld_elf_hints_path != NULL) || ld_loadfltr;
ld_tracing = getenv(LD_ "TRACE_LOADED_OBJECTS");
ld_utrace = getenv(LD_ "UTRACE");
if ((ld_elf_hints_path == NULL) || strlen(ld_elf_hints_path) == 0)
ld_elf_hints_path = _PATH_ELF_HINTS;
if (ld_debug != NULL && *ld_debug != '\0')
debug = 1;
dbg("%s is initialized, base address = %p", __progname,
(caddr_t) aux_info[AT_BASE]->a_un.a_ptr);
dbg("RTLD dynamic = %p", obj_rtld.dynamic);
dbg("RTLD pltgot = %p", obj_rtld.pltgot);
dbg("initializing thread locks");
lockdflt_init();
/*
* Load the main program, or process its program header if it is
* already loaded.
*/
if (aux_info[AT_EXECFD] != NULL) { /* Load the main program. */
int fd = aux_info[AT_EXECFD]->a_un.a_val;
dbg("loading main program");
obj_main = map_object(fd, argv0, NULL);
close(fd);
if (obj_main == NULL)
die();
max_stack_flags = obj->stack_flags;
} else { /* Main program already loaded. */
const Elf_Phdr *phdr;
int phnum;
caddr_t entry;
dbg("processing main program's program header");
assert(aux_info[AT_PHDR] != NULL);
phdr = (const Elf_Phdr *) aux_info[AT_PHDR]->a_un.a_ptr;
assert(aux_info[AT_PHNUM] != NULL);
phnum = aux_info[AT_PHNUM]->a_un.a_val;
assert(aux_info[AT_PHENT] != NULL);
assert(aux_info[AT_PHENT]->a_un.a_val == sizeof(Elf_Phdr));
assert(aux_info[AT_ENTRY] != NULL);
entry = (caddr_t) aux_info[AT_ENTRY]->a_un.a_ptr;
if ((obj_main = digest_phdr(phdr, phnum, entry, argv0)) == NULL)
die();
}
if (aux_info[AT_EXECPATH] != 0) {
char *kexecpath;
char buf[MAXPATHLEN];
kexecpath = aux_info[AT_EXECPATH]->a_un.a_ptr;
dbg("AT_EXECPATH %p %s", kexecpath, kexecpath);
if (kexecpath[0] == '/')
obj_main->path = kexecpath;
else if (getcwd(buf, sizeof(buf)) == NULL ||
strlcat(buf, "/", sizeof(buf)) >= sizeof(buf) ||
strlcat(buf, kexecpath, sizeof(buf)) >= sizeof(buf))
obj_main->path = xstrdup(argv0);
else
obj_main->path = xstrdup(buf);
} else {
dbg("No AT_EXECPATH");
obj_main->path = xstrdup(argv0);
}
dbg("obj_main path %s", obj_main->path);
obj_main->mainprog = true;
if (aux_info[AT_STACKPROT] != NULL &&
aux_info[AT_STACKPROT]->a_un.a_val != 0)
stack_prot = aux_info[AT_STACKPROT]->a_un.a_val;
/*
* Get the actual dynamic linker pathname from the executable if
* possible. (It should always be possible.) That ensures that
* gdb will find the right dynamic linker even if a non-standard
* one is being used.
*/
if (obj_main->interp != NULL &&
strcmp(obj_main->interp, obj_rtld.path) != 0) {
free(obj_rtld.path);
obj_rtld.path = xstrdup(obj_main->interp);
__progname = obj_rtld.path;
}
digest_dynamic(obj_main, 0);
dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d",
obj_main->path, obj_main->valid_hash_sysv, obj_main->valid_hash_gnu,
obj_main->dynsymcount);
linkmap_add(obj_main);
linkmap_add(&obj_rtld);
/* Link the main program into the list of objects. */
*obj_tail = obj_main;
obj_tail = &obj_main->next;
obj_count++;
obj_loads++;
/* Initialize a fake symbol for resolving undefined weak references. */
sym_zero.st_info = ELF_ST_INFO(STB_GLOBAL, STT_NOTYPE);
sym_zero.st_shndx = SHN_UNDEF;
sym_zero.st_value = -(uintptr_t)obj_main->relocbase;
if (!libmap_disable)
libmap_disable = (bool)lm_init(libmap_override);
dbg("loading LD_PRELOAD libraries");
if (load_preload_objects() == -1)
die();
preload_tail = obj_tail;
dbg("loading needed objects");
if (load_needed_objects(obj_main, 0) == -1)
die();
/* Make a list of all objects loaded at startup. */
last_interposer = obj_main;
for (obj = obj_list; obj != NULL; obj = obj->next) {
if (obj->z_interpose && obj != obj_main) {
objlist_put_after(&list_main, last_interposer, obj);
last_interposer = obj;
} else {
objlist_push_tail(&list_main, obj);
}
obj->refcount++;
}
dbg("checking for required versions");
if (rtld_verify_versions(&list_main) == -1 && !ld_tracing)
die();
if (ld_tracing) { /* We're done */
trace_loaded_objects(obj_main);
exit(0);
}
if (getenv(LD_ "DUMP_REL_PRE") != NULL) {
dump_relocations(obj_main);
exit (0);
}
/*
* Processing tls relocations requires having the tls offsets
* initialized. Prepare offsets before starting initial
* relocation processing.
*/
dbg("initializing initial thread local storage offsets");
STAILQ_FOREACH(entry, &list_main, link) {
/*
* Allocate all the initial objects out of the static TLS
* block even if they didn't ask for it.
*/
allocate_tls_offset(entry->obj);
}
if (relocate_objects(obj_main,
ld_bind_now != NULL && *ld_bind_now != '\0',
&obj_rtld, SYMLOOK_EARLY, NULL) == -1)
die();
dbg("doing copy relocations");
if (do_copy_relocations(obj_main) == -1)
die();
if (getenv(LD_ "DUMP_REL_POST") != NULL) {
dump_relocations(obj_main);
exit (0);
}
/*
* Setup TLS for main thread. This must be done after the
* relocations are processed, since tls initialization section
* might be the subject for relocations.
*/
dbg("initializing initial thread local storage");
allocate_initial_tls(obj_list);
dbg("initializing key program variables");
set_program_var("__progname", argv[0] != NULL ? basename(argv[0]) : "");
set_program_var("environ", env);
set_program_var("__elf_aux_vector", aux);
/* Make a list of init functions to call. */
objlist_init(&initlist);
initlist_add_objects(obj_list, preload_tail, &initlist);
r_debug_state(NULL, &obj_main->linkmap); /* say hello to gdb! */
map_stacks_exec(NULL);
dbg("resolving ifuncs");
if (resolve_objects_ifunc(obj_main,
ld_bind_now != NULL && *ld_bind_now != '\0', SYMLOOK_EARLY,
NULL) == -1)
die();
if (!obj_main->crt_no_init) {
/*
* Make sure we don't call the main program's init and fini
* functions for binaries linked with old crt1 which calls
* _init itself.
*/
obj_main->init = obj_main->fini = (Elf_Addr)NULL;
obj_main->preinit_array = obj_main->init_array =
obj_main->fini_array = (Elf_Addr)NULL;
}
wlock_acquire(rtld_bind_lock, &lockstate);
if (obj_main->crt_no_init)
preinit_main();
objlist_call_init(&initlist, &lockstate);
objlist_clear(&initlist);
dbg("loading filtees");
for (obj = obj_list->next; obj != NULL; obj = obj->next) {
if (ld_loadfltr || obj->z_loadfltr)
load_filtees(obj, 0, &lockstate);
}
lock_release(rtld_bind_lock, &lockstate);
dbg("transferring control to program entry point = %p", obj_main->entry);
/* Return the exit procedure and the program entry point. */
*exit_proc = rtld_exit;
*objp = obj_main;
return (func_ptr_type) obj_main->entry;
}
void *
rtld_resolve_ifunc(const Obj_Entry *obj, const Elf_Sym *def)
{
void *ptr;
Elf_Addr target;
ptr = (void *)make_function_pointer(def, obj);
target = ((Elf_Addr (*)(void))ptr)();
return ((void *)target);
}
Elf_Addr
_rtld_bind(Obj_Entry *obj, Elf_Size reloff)
{
const Elf_Rel *rel;
const Elf_Sym *def;
const Obj_Entry *defobj;
Elf_Addr *where;
Elf_Addr target;
RtldLockState lockstate;
rlock_acquire(rtld_bind_lock, &lockstate);
if (sigsetjmp(lockstate.env, 0) != 0)
lock_upgrade(rtld_bind_lock, &lockstate);
if (obj->pltrel)
rel = (const Elf_Rel *) ((caddr_t) obj->pltrel + reloff);
else
rel = (const Elf_Rel *) ((caddr_t) obj->pltrela + reloff);
where = (Elf_Addr *) (obj->relocbase + rel->r_offset);
def = find_symdef(ELF_R_SYM(rel->r_info), obj, &defobj, true, NULL,
&lockstate);
if (def == NULL)
die();
if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
else
target = (Elf_Addr)(defobj->relocbase + def->st_value);
dbg("\"%s\" in \"%s\" ==> %p in \"%s\"",
defobj->strtab + def->st_name, basename(obj->path),
(void *)target, basename(defobj->path));
/*
* Write the new contents for the jmpslot. Note that depending on
* architecture, the value which we need to return back to the
* lazy binding trampoline may or may not be the target
* address. The value returned from reloc_jmpslot() is the value
* that the trampoline needs.
*/
target = reloc_jmpslot(where, target, defobj, obj, rel);
lock_release(rtld_bind_lock, &lockstate);
return target;
}
/*
* Error reporting function. Use it like printf. If formats the message
* into a buffer, and sets things up so that the next call to dlerror()
* will return the message.
*/
void
_rtld_error(const char *fmt, ...)
{
static char buf[512];
va_list ap;
va_start(ap, fmt);
rtld_vsnprintf(buf, sizeof buf, fmt, ap);
error_message = buf;
va_end(ap);
}
/*
* Return a dynamically-allocated copy of the current error message, if any.
*/
static char *
errmsg_save(void)
{
return error_message == NULL ? NULL : xstrdup(error_message);
}
/*
* Restore the current error message from a copy which was previously saved
* by errmsg_save(). The copy is freed.
*/
static void
errmsg_restore(char *saved_msg)
{
if (saved_msg == NULL)
error_message = NULL;
else {
_rtld_error("%s", saved_msg);
free(saved_msg);
}
}
static const char *
basename(const char *name)
{
const char *p = strrchr(name, '/');
return p != NULL ? p + 1 : name;
}
static struct utsname uts;
static char *
origin_subst_one(char *real, const char *kw, const char *subst,
bool may_free)
{
char *p, *p1, *res, *resp;
int subst_len, kw_len, subst_count, old_len, new_len;
kw_len = strlen(kw);
/*
* First, count the number of the keyword occurences, to
* preallocate the final string.
*/
for (p = real, subst_count = 0;; p = p1 + kw_len, subst_count++) {
p1 = strstr(p, kw);
if (p1 == NULL)
break;
}
/*
* If the keyword is not found, just return.
*/
if (subst_count == 0)
return (may_free ? real : xstrdup(real));
/*
* There is indeed something to substitute. Calculate the
* length of the resulting string, and allocate it.
*/
subst_len = strlen(subst);
old_len = strlen(real);
new_len = old_len + (subst_len - kw_len) * subst_count;
res = xmalloc(new_len + 1);
/*
* Now, execute the substitution loop.
*/
for (p = real, resp = res, *resp = '\0';;) {
p1 = strstr(p, kw);
if (p1 != NULL) {
/* Copy the prefix before keyword. */
memcpy(resp, p, p1 - p);
resp += p1 - p;
/* Keyword replacement. */
memcpy(resp, subst, subst_len);
resp += subst_len;
*resp = '\0';
p = p1 + kw_len;
} else
break;
}
/* Copy to the end of string and finish. */
strcat(resp, p);
if (may_free)
free(real);
return (res);
}
static char *
origin_subst(char *real, const char *origin_path)
{
char *res1, *res2, *res3, *res4;
if (uts.sysname[0] == '\0') {
if (uname(&uts) != 0) {
_rtld_error("utsname failed: %d", errno);
return (NULL);
}
}
res1 = origin_subst_one(real, "$ORIGIN", origin_path, false);
res2 = origin_subst_one(res1, "$OSNAME", uts.sysname, true);
res3 = origin_subst_one(res2, "$OSREL", uts.release, true);
res4 = origin_subst_one(res3, "$PLATFORM", uts.machine, true);
return (res4);
}
static void
die(void)
{
const char *msg = dlerror();
if (msg == NULL)
msg = "Fatal error";
rtld_fdputstr(STDERR_FILENO, msg);
rtld_fdputchar(STDERR_FILENO, '\n');
_exit(1);
}
/*
* Process a shared object's DYNAMIC section, and save the important
* information in its Obj_Entry structure.
*/
static void
digest_dynamic1(Obj_Entry *obj, int early, const Elf_Dyn **dyn_rpath,
const Elf_Dyn **dyn_soname, const Elf_Dyn **dyn_runpath)
{
const Elf_Dyn *dynp;
Needed_Entry **needed_tail = &obj->needed;
Needed_Entry **needed_filtees_tail = &obj->needed_filtees;
Needed_Entry **needed_aux_filtees_tail = &obj->needed_aux_filtees;
const Elf_Hashelt *hashtab;
const Elf32_Word *hashval;
Elf32_Word bkt, nmaskwords;
unsigned int bloom_size32;
bool nmw_power2;
int plttype = DT_REL;
*dyn_rpath = NULL;
*dyn_soname = NULL;
*dyn_runpath = NULL;
obj->bind_now = false;
for (dynp = obj->dynamic; dynp->d_tag != DT_NULL; dynp++) {
switch (dynp->d_tag) {
case DT_REL:
obj->rel = (const Elf_Rel *) (obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_RELSZ:
obj->relsize = dynp->d_un.d_val;
break;
case DT_RELENT:
assert(dynp->d_un.d_val == sizeof(Elf_Rel));
break;
case DT_JMPREL:
obj->pltrel = (const Elf_Rel *)
(obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_PLTRELSZ:
obj->pltrelsize = dynp->d_un.d_val;
break;
case DT_RELA:
obj->rela = (const Elf_Rela *) (obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_RELASZ:
obj->relasize = dynp->d_un.d_val;
break;
case DT_RELAENT:
assert(dynp->d_un.d_val == sizeof(Elf_Rela));
break;
case DT_PLTREL:
plttype = dynp->d_un.d_val;
assert(dynp->d_un.d_val == DT_REL || plttype == DT_RELA);
break;
case DT_SYMTAB:
obj->symtab = (const Elf_Sym *)
(obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_SYMENT:
assert(dynp->d_un.d_val == sizeof(Elf_Sym));
break;
case DT_STRTAB:
obj->strtab = (const char *) (obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_STRSZ:
obj->strsize = dynp->d_un.d_val;
break;
case DT_VERNEED:
obj->verneed = (const Elf_Verneed *) (obj->relocbase +
dynp->d_un.d_val);
break;
case DT_VERNEEDNUM:
obj->verneednum = dynp->d_un.d_val;
break;
case DT_VERDEF:
obj->verdef = (const Elf_Verdef *) (obj->relocbase +
dynp->d_un.d_val);
break;
case DT_VERDEFNUM:
obj->verdefnum = dynp->d_un.d_val;
break;
case DT_VERSYM:
obj->versyms = (const Elf_Versym *)(obj->relocbase +
dynp->d_un.d_val);
break;
case DT_HASH:
{
hashtab = (const Elf_Hashelt *)(obj->relocbase +
dynp->d_un.d_ptr);
obj->nbuckets = hashtab[0];
obj->nchains = hashtab[1];
obj->buckets = hashtab + 2;
obj->chains = obj->buckets + obj->nbuckets;
obj->valid_hash_sysv = obj->nbuckets > 0 && obj->nchains > 0 &&
obj->buckets != NULL;
}
break;
case DT_GNU_HASH:
{
hashtab = (const Elf_Hashelt *)(obj->relocbase +
dynp->d_un.d_ptr);
obj->nbuckets_gnu = hashtab[0];
obj->symndx_gnu = hashtab[1];
nmaskwords = hashtab[2];
bloom_size32 = (__ELF_WORD_SIZE / 32) * nmaskwords;
/* Number of bitmask words is required to be power of 2 */
nmw_power2 = ((nmaskwords & (nmaskwords - 1)) == 0);
obj->maskwords_bm_gnu = nmaskwords - 1;
obj->shift2_gnu = hashtab[3];
obj->bloom_gnu = (Elf_Addr *) (hashtab + 4);
obj->buckets_gnu = hashtab + 4 + bloom_size32;
obj->chain_zero_gnu = obj->buckets_gnu + obj->nbuckets_gnu -
obj->symndx_gnu;
obj->valid_hash_gnu = nmw_power2 && obj->nbuckets_gnu > 0 &&
obj->buckets_gnu != NULL;
}
break;
case DT_NEEDED:
if (!obj->rtld) {
Needed_Entry *nep = NEW(Needed_Entry);
nep->name = dynp->d_un.d_val;
nep->obj = NULL;
nep->next = NULL;
*needed_tail = nep;
needed_tail = &nep->next;
}
break;
case DT_FILTER:
if (!obj->rtld) {
Needed_Entry *nep = NEW(Needed_Entry);
nep->name = dynp->d_un.d_val;
nep->obj = NULL;
nep->next = NULL;
*needed_filtees_tail = nep;
needed_filtees_tail = &nep->next;
}
break;
case DT_AUXILIARY:
if (!obj->rtld) {
Needed_Entry *nep = NEW(Needed_Entry);
nep->name = dynp->d_un.d_val;
nep->obj = NULL;
nep->next = NULL;
*needed_aux_filtees_tail = nep;
needed_aux_filtees_tail = &nep->next;
}
break;
case DT_PLTGOT:
obj->pltgot = (Elf_Addr *) (obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_TEXTREL:
obj->textrel = true;
break;
case DT_SYMBOLIC:
obj->symbolic = true;
break;
case DT_RPATH:
/*
* We have to wait until later to process this, because we
* might not have gotten the address of the string table yet.
*/
*dyn_rpath = dynp;
break;
case DT_SONAME:
*dyn_soname = dynp;
break;
case DT_RUNPATH:
*dyn_runpath = dynp;
break;
case DT_INIT:
obj->init = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_PREINIT_ARRAY:
obj->preinit_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_PREINIT_ARRAYSZ:
obj->preinit_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
break;
case DT_INIT_ARRAY:
obj->init_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_INIT_ARRAYSZ:
obj->init_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
break;
case DT_FINI:
obj->fini = (Elf_Addr) (obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_FINI_ARRAY:
obj->fini_array = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
break;
case DT_FINI_ARRAYSZ:
obj->fini_array_num = dynp->d_un.d_val / sizeof(Elf_Addr);
break;
/*
* Don't process DT_DEBUG on MIPS as the dynamic section
* is mapped read-only. DT_MIPS_RLD_MAP is used instead.
*/
#ifndef __mips__
case DT_DEBUG:
/* XXX - not implemented yet */
if (!early)
dbg("Filling in DT_DEBUG entry");
((Elf_Dyn*)dynp)->d_un.d_ptr = (Elf_Addr) &r_debug;
break;
#endif
case DT_FLAGS:
if ((dynp->d_un.d_val & DF_ORIGIN) && trust)
obj->z_origin = true;
if (dynp->d_un.d_val & DF_SYMBOLIC)
obj->symbolic = true;
if (dynp->d_un.d_val & DF_TEXTREL)
obj->textrel = true;
if (dynp->d_un.d_val & DF_BIND_NOW)
obj->bind_now = true;
/*if (dynp->d_un.d_val & DF_STATIC_TLS)
;*/
break;
#ifdef __mips__
case DT_MIPS_LOCAL_GOTNO:
obj->local_gotno = dynp->d_un.d_val;
break;
case DT_MIPS_SYMTABNO:
obj->symtabno = dynp->d_un.d_val;
break;
case DT_MIPS_GOTSYM:
obj->gotsym = dynp->d_un.d_val;
break;
case DT_MIPS_RLD_MAP:
*((Elf_Addr *)(dynp->d_un.d_ptr)) = (Elf_Addr) &r_debug;
break;
#endif
case DT_FLAGS_1:
if (dynp->d_un.d_val & DF_1_NOOPEN)
obj->z_noopen = true;
if ((dynp->d_un.d_val & DF_1_ORIGIN) && trust)
obj->z_origin = true;
/*if (dynp->d_un.d_val & DF_1_GLOBAL)
XXX ;*/
if (dynp->d_un.d_val & DF_1_BIND_NOW)
obj->bind_now = true;
if (dynp->d_un.d_val & DF_1_NODELETE)
obj->z_nodelete = true;
if (dynp->d_un.d_val & DF_1_LOADFLTR)
obj->z_loadfltr = true;
if (dynp->d_un.d_val & DF_1_INTERPOSE)
obj->z_interpose = true;
if (dynp->d_un.d_val & DF_1_NODEFLIB)
obj->z_nodeflib = true;
break;
default:
if (!early) {
dbg("Ignoring d_tag %ld = %#lx", (long)dynp->d_tag,
(long)dynp->d_tag);
}
break;
}
}
obj->traced = false;
if (plttype == DT_RELA) {
obj->pltrela = (const Elf_Rela *) obj->pltrel;
obj->pltrel = NULL;
obj->pltrelasize = obj->pltrelsize;
obj->pltrelsize = 0;
}
/* Determine size of dynsym table (equal to nchains of sysv hash) */
if (obj->valid_hash_sysv)
obj->dynsymcount = obj->nchains;
else if (obj->valid_hash_gnu) {
obj->dynsymcount = 0;
for (bkt = 0; bkt < obj->nbuckets_gnu; bkt++) {
if (obj->buckets_gnu[bkt] == 0)
continue;
hashval = &obj->chain_zero_gnu[obj->buckets_gnu[bkt]];
do
obj->dynsymcount++;
while ((*hashval++ & 1u) == 0);
}
obj->dynsymcount += obj->symndx_gnu;
}
}
static void
digest_dynamic2(Obj_Entry *obj, const Elf_Dyn *dyn_rpath,
const Elf_Dyn *dyn_soname, const Elf_Dyn *dyn_runpath)
{
if (obj->z_origin && obj->origin_path == NULL) {
obj->origin_path = xmalloc(PATH_MAX);
if (rtld_dirname_abs(obj->path, obj->origin_path) == -1)
die();
}
if (dyn_runpath != NULL) {
obj->runpath = (char *)obj->strtab + dyn_runpath->d_un.d_val;
if (obj->z_origin)
obj->runpath = origin_subst(obj->runpath, obj->origin_path);
}
else if (dyn_rpath != NULL) {
obj->rpath = (char *)obj->strtab + dyn_rpath->d_un.d_val;
if (obj->z_origin)
obj->rpath = origin_subst(obj->rpath, obj->origin_path);
}
if (dyn_soname != NULL)
object_add_name(obj, obj->strtab + dyn_soname->d_un.d_val);
}
static void
digest_dynamic(Obj_Entry *obj, int early)
{
const Elf_Dyn *dyn_rpath;
const Elf_Dyn *dyn_soname;
const Elf_Dyn *dyn_runpath;
digest_dynamic1(obj, early, &dyn_rpath, &dyn_soname, &dyn_runpath);
digest_dynamic2(obj, dyn_rpath, dyn_soname, dyn_runpath);
}
/*
* Process a shared object's program header. This is used only for the
* main program, when the kernel has already loaded the main program
* into memory before calling the dynamic linker. It creates and
* returns an Obj_Entry structure.
*/
static Obj_Entry *
digest_phdr(const Elf_Phdr *phdr, int phnum, caddr_t entry, const char *path)
{
Obj_Entry *obj;
const Elf_Phdr *phlimit = phdr + phnum;
const Elf_Phdr *ph;
Elf_Addr note_start, note_end;
int nsegs = 0;
obj = obj_new();
for (ph = phdr; ph < phlimit; ph++) {
if (ph->p_type != PT_PHDR)
continue;
obj->phdr = phdr;
obj->phsize = ph->p_memsz;
obj->relocbase = (caddr_t)phdr - ph->p_vaddr;
break;
}
obj->stack_flags = PF_X | PF_R | PF_W;
for (ph = phdr; ph < phlimit; ph++) {
switch (ph->p_type) {
case PT_INTERP:
obj->interp = (const char *)(ph->p_vaddr + obj->relocbase);
break;
case PT_LOAD:
if (nsegs == 0) { /* First load segment */
obj->vaddrbase = trunc_page(ph->p_vaddr);
obj->mapbase = obj->vaddrbase + obj->relocbase;
obj->textsize = round_page(ph->p_vaddr + ph->p_memsz) -
obj->vaddrbase;
} else { /* Last load segment */
obj->mapsize = round_page(ph->p_vaddr + ph->p_memsz) -
obj->vaddrbase;
}
nsegs++;
break;
case PT_DYNAMIC:
obj->dynamic = (const Elf_Dyn *)(ph->p_vaddr + obj->relocbase);
break;
case PT_TLS:
obj->tlsindex = 1;
obj->tlssize = ph->p_memsz;
obj->tlsalign = ph->p_align;
obj->tlsinitsize = ph->p_filesz;
obj->tlsinit = (void*)(ph->p_vaddr + obj->relocbase);
break;
case PT_GNU_STACK:
obj->stack_flags = ph->p_flags;
break;
case PT_GNU_RELRO:
obj->relro_page = obj->relocbase + trunc_page(ph->p_vaddr);
obj->relro_size = round_page(ph->p_memsz);
break;
case PT_NOTE:
note_start = (Elf_Addr)obj->relocbase + ph->p_vaddr;
note_end = note_start + ph->p_filesz;
digest_notes(obj, note_start, note_end);
break;
}
}
if (nsegs < 1) {
_rtld_error("%s: too few PT_LOAD segments", path);
return NULL;
}
obj->entry = entry;
return obj;
}
void
digest_notes(Obj_Entry *obj, Elf_Addr note_start, Elf_Addr note_end)
{
const Elf_Note *note;
const char *note_name;
uintptr_t p;
for (note = (const Elf_Note *)note_start; (Elf_Addr)note < note_end;
note = (const Elf_Note *)((const char *)(note + 1) +
roundup2(note->n_namesz, sizeof(Elf32_Addr)) +
roundup2(note->n_descsz, sizeof(Elf32_Addr)))) {
if (note->n_namesz != sizeof(NOTE_FREEBSD_VENDOR) ||
note->n_descsz != sizeof(int32_t))
continue;
if (note->n_type != ABI_NOTETYPE &&
note->n_type != CRT_NOINIT_NOTETYPE)
continue;
note_name = (const char *)(note + 1);
if (strncmp(NOTE_FREEBSD_VENDOR, note_name,
sizeof(NOTE_FREEBSD_VENDOR)) != 0)
continue;
switch (note->n_type) {
case ABI_NOTETYPE:
/* FreeBSD osrel note */
p = (uintptr_t)(note + 1);
p += roundup2(note->n_namesz, sizeof(Elf32_Addr));
obj->osrel = *(const int32_t *)(p);
dbg("note osrel %d", obj->osrel);
break;
case CRT_NOINIT_NOTETYPE:
/* FreeBSD 'crt does not call init' note */
obj->crt_no_init = true;
dbg("note crt_no_init");
break;
}
}
}
static Obj_Entry *
dlcheck(void *handle)
{
Obj_Entry *obj;
for (obj = obj_list; obj != NULL; obj = obj->next)
if (obj == (Obj_Entry *) handle)
break;
if (obj == NULL || obj->refcount == 0 || obj->dl_refcount == 0) {
_rtld_error("Invalid shared object handle %p", handle);
return NULL;
}
return obj;
}
/*
* If the given object is already in the donelist, return true. Otherwise
* add the object to the list and return false.
*/
static bool
donelist_check(DoneList *dlp, const Obj_Entry *obj)
{
unsigned int i;
for (i = 0; i < dlp->num_used; i++)
if (dlp->objs[i] == obj)
return true;
/*
* Our donelist allocation should always be sufficient. But if
* our threads locking isn't working properly, more shared objects
* could have been loaded since we allocated the list. That should
* never happen, but we'll handle it properly just in case it does.
*/
if (dlp->num_used < dlp->num_alloc)
dlp->objs[dlp->num_used++] = obj;
return false;
}
/*
* Hash function for symbol table lookup. Don't even think about changing
* this. It is specified by the System V ABI.
*/
unsigned long
elf_hash(const char *name)
{
const unsigned char *p = (const unsigned char *) name;
unsigned long h = 0;
unsigned long g;
while (*p != '\0') {
h = (h << 4) + *p++;
if ((g = h & 0xf0000000) != 0)
h ^= g >> 24;
h &= ~g;
}
return h;
}
/*
* The GNU hash function is the Daniel J. Bernstein hash clipped to 32 bits
* unsigned in case it's implemented with a wider type.
*/
static uint32_t
gnu_hash(const char *s)
{
uint32_t h;
unsigned char c;
h = 5381;
for (c = *s; c != '\0'; c = *++s)
h = h * 33 + c;
return (h & 0xffffffff);
}
/*
* Find the library with the given name, and return its full pathname.
* The returned string is dynamically allocated. Generates an error
* message and returns NULL if the library cannot be found.
*
* If the second argument is non-NULL, then it refers to an already-
* loaded shared object, whose library search path will be searched.
*
* The search order is:
* DT_RPATH in the referencing file _unless_ DT_RUNPATH is present (1)
* DT_RPATH of the main object if DSO without defined DT_RUNPATH (1)
* LD_LIBRARY_PATH
* DT_RUNPATH in the referencing file
* ldconfig hints (if -z nodefaultlib, filter out default library directories
* from list)
* /lib:/usr/lib _unless_ the referencing file is linked with -z nodefaultlib
*
* (1) Handled in digest_dynamic2 - rpath left NULL if runpath defined.
*/
static char *
find_library(const char *xname, const Obj_Entry *refobj)
{
char *pathname;
char *name;
bool nodeflib, objgiven;
objgiven = refobj != NULL;
if (strchr(xname, '/') != NULL) { /* Hard coded pathname */
if (xname[0] != '/' && !trust) {
_rtld_error("Absolute pathname required for shared object \"%s\"",
xname);
return NULL;
}
if (objgiven && refobj->z_origin) {
return (origin_subst(__DECONST(char *, xname),
refobj->origin_path));
} else {
return (xstrdup(xname));
}
}
if (libmap_disable || !objgiven ||
(name = lm_find(refobj->path, xname)) == NULL)
name = (char *)xname;
dbg(" Searching for \"%s\"", name);
/*
* If refobj->rpath != NULL, then refobj->runpath is NULL. Fall
* back to pre-conforming behaviour if user requested so with
* LD_LIBRARY_PATH_RPATH environment variable and ignore -z
* nodeflib.
*/
if (objgiven && refobj->rpath != NULL && ld_library_path_rpath) {
if ((pathname = search_library_path(name, ld_library_path)) != NULL ||
(refobj != NULL &&
(pathname = search_library_path(name, refobj->rpath)) != NULL) ||
(pathname = search_library_path(name, gethints(false))) != NULL ||
(pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL)
return (pathname);
} else {
nodeflib = objgiven ? refobj->z_nodeflib : false;
if ((objgiven &&
(pathname = search_library_path(name, refobj->rpath)) != NULL) ||
(objgiven && refobj->runpath == NULL && refobj != obj_main &&
(pathname = search_library_path(name, obj_main->rpath)) != NULL) ||
(pathname = search_library_path(name, ld_library_path)) != NULL ||
(objgiven &&
(pathname = search_library_path(name, refobj->runpath)) != NULL) ||
(pathname = search_library_path(name, gethints(nodeflib))) != NULL ||
(objgiven && !nodeflib &&
(pathname = search_library_path(name, STANDARD_LIBRARY_PATH)) != NULL))
return (pathname);
}
if (objgiven && refobj->path != NULL) {
_rtld_error("Shared object \"%s\" not found, required by \"%s\"",
name, basename(refobj->path));
} else {
_rtld_error("Shared object \"%s\" not found", name);
}
return NULL;
}
/*
* Given a symbol number in a referencing object, find the corresponding
* definition of the symbol. Returns a pointer to the symbol, or NULL if
* no definition was found. Returns a pointer to the Obj_Entry of the
* defining object via the reference parameter DEFOBJ_OUT.
*/
const Elf_Sym *
find_symdef(unsigned long symnum, const Obj_Entry *refobj,
const Obj_Entry **defobj_out, int flags, SymCache *cache,
RtldLockState *lockstate)
{
const Elf_Sym *ref;
const Elf_Sym *def;
const Obj_Entry *defobj;
SymLook req;
const char *name;
int res;
/*
* If we have already found this symbol, get the information from
* the cache.
*/
if (symnum >= refobj->dynsymcount)
return NULL; /* Bad object */
if (cache != NULL && cache[symnum].sym != NULL) {
*defobj_out = cache[symnum].obj;
return cache[symnum].sym;
}
ref = refobj->symtab + symnum;
name = refobj->strtab + ref->st_name;
def = NULL;
defobj = NULL;
/*
* We don't have to do a full scale lookup if the symbol is local.
* We know it will bind to the instance in this load module; to
* which we already have a pointer (ie ref). By not doing a lookup,
* we not only improve performance, but it also avoids unresolvable
* symbols when local symbols are not in the hash table. This has
* been seen with the ia64 toolchain.
*/
if (ELF_ST_BIND(ref->st_info) != STB_LOCAL) {
if (ELF_ST_TYPE(ref->st_info) == STT_SECTION) {
_rtld_error("%s: Bogus symbol table entry %lu", refobj->path,
symnum);
}
symlook_init(&req, name);
req.flags = flags;
req.ventry = fetch_ventry(refobj, symnum);
req.lockstate = lockstate;
res = symlook_default(&req, refobj);
if (res == 0) {
def = req.sym_out;
defobj = req.defobj_out;
}
} else {
def = ref;
defobj = refobj;
}
/*
* If we found no definition and the reference is weak, treat the
* symbol as having the value zero.
*/
if (def == NULL && ELF_ST_BIND(ref->st_info) == STB_WEAK) {
def = &sym_zero;
defobj = obj_main;
}
if (def != NULL) {
*defobj_out = defobj;
/* Record the information in the cache to avoid subsequent lookups. */
if (cache != NULL) {
cache[symnum].sym = def;
cache[symnum].obj = defobj;
}
} else {
if (refobj != &obj_rtld)
_rtld_error("%s: Undefined symbol \"%s\"", refobj->path, name);
}
return def;
}
/*
* Return the search path from the ldconfig hints file, reading it if
* necessary. If nostdlib is true, then the default search paths are
* not added to result.
*
* Returns NULL if there are problems with the hints file,
* or if the search path there is empty.
*/
static const char *
gethints(bool nostdlib)
{
static char *hints, *filtered_path;
struct elfhints_hdr hdr;
struct fill_search_info_args sargs, hargs;
struct dl_serinfo smeta, hmeta, *SLPinfo, *hintinfo;
struct dl_serpath *SLPpath, *hintpath;
char *p;
unsigned int SLPndx, hintndx, fndx, fcount;
int fd;
size_t flen;
bool skip;
/* First call, read the hints file */
if (hints == NULL) {
/* Keep from trying again in case the hints file is bad. */
hints = "";
if ((fd = open(ld_elf_hints_path, O_RDONLY | O_CLOEXEC)) == -1)
return (NULL);
if (read(fd, &hdr, sizeof hdr) != sizeof hdr ||
hdr.magic != ELFHINTS_MAGIC ||
hdr.version != 1) {
close(fd);
return (NULL);
}
p = xmalloc(hdr.dirlistlen + 1);
if (lseek(fd, hdr.strtab + hdr.dirlist, SEEK_SET) == -1 ||
read(fd, p, hdr.dirlistlen + 1) !=
(ssize_t)hdr.dirlistlen + 1) {
free(p);
close(fd);
return (NULL);
}
hints = p;
close(fd);
}
/*
* If caller agreed to receive list which includes the default
* paths, we are done. Otherwise, if we still did not
* calculated filtered result, do it now.
*/
if (!nostdlib)
return (hints[0] != '\0' ? hints : NULL);
if (filtered_path != NULL)
goto filt_ret;
/*
* Obtain the list of all configured search paths, and the
* list of the default paths.
*
* First estimate the size of the results.
*/
smeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
smeta.dls_cnt = 0;
hmeta.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
hmeta.dls_cnt = 0;
sargs.request = RTLD_DI_SERINFOSIZE;
sargs.serinfo = &smeta;
hargs.request = RTLD_DI_SERINFOSIZE;
hargs.serinfo = &hmeta;
path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
path_enumerate(p, fill_search_info, &hargs);
SLPinfo = xmalloc(smeta.dls_size);
hintinfo = xmalloc(hmeta.dls_size);
/*
* Next fetch both sets of paths.
*/
sargs.request = RTLD_DI_SERINFO;
sargs.serinfo = SLPinfo;
sargs.serpath = &SLPinfo->dls_serpath[0];
sargs.strspace = (char *)&SLPinfo->dls_serpath[smeta.dls_cnt];
hargs.request = RTLD_DI_SERINFO;
hargs.serinfo = hintinfo;
hargs.serpath = &hintinfo->dls_serpath[0];
hargs.strspace = (char *)&hintinfo->dls_serpath[hmeta.dls_cnt];
path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &sargs);
path_enumerate(p, fill_search_info, &hargs);
/*
* Now calculate the difference between two sets, by excluding
* standard paths from the full set.
*/
fndx = 0;
fcount = 0;
filtered_path = xmalloc(hdr.dirlistlen + 1);
hintpath = &hintinfo->dls_serpath[0];
for (hintndx = 0; hintndx < hmeta.dls_cnt; hintndx++, hintpath++) {
skip = false;
SLPpath = &SLPinfo->dls_serpath[0];
/*
* Check each standard path against current.
*/
for (SLPndx = 0; SLPndx < smeta.dls_cnt; SLPndx++, SLPpath++) {
/* matched, skip the path */
if (!strcmp(hintpath->dls_name, SLPpath->dls_name)) {
skip = true;
break;
}
}
if (skip)
continue;
/*
* Not matched against any standard path, add the path
* to result. Separate consequtive paths with ':'.
*/
if (fcount > 0) {
filtered_path[fndx] = ':';
fndx++;
}
fcount++;
flen = strlen(hintpath->dls_name);
strncpy((filtered_path + fndx), hintpath->dls_name, flen);
fndx += flen;
}
filtered_path[fndx] = '\0';
free(SLPinfo);
free(hintinfo);
filt_ret:
return (filtered_path[0] != '\0' ? filtered_path : NULL);
}
static void
init_dag(Obj_Entry *root)
{
const Needed_Entry *needed;
const Objlist_Entry *elm;
DoneList donelist;
if (root->dag_inited)
return;
donelist_init(&donelist);
/* Root object belongs to own DAG. */
objlist_push_tail(&root->dldags, root);
objlist_push_tail(&root->dagmembers, root);
donelist_check(&donelist, root);
/*
* Add dependencies of root object to DAG in breadth order
* by exploiting the fact that each new object get added
* to the tail of the dagmembers list.
*/
STAILQ_FOREACH(elm, &root->dagmembers, link) {
for (needed = elm->obj->needed; needed != NULL; needed = needed->next) {
if (needed->obj == NULL || donelist_check(&donelist, needed->obj))
continue;
objlist_push_tail(&needed->obj->dldags, root);
objlist_push_tail(&root->dagmembers, needed->obj);
}
}
root->dag_inited = true;
}
static void
process_nodelete(Obj_Entry *root)
{
const Objlist_Entry *elm;
/*
* Walk over object DAG and process every dependent object that
* is marked as DF_1_NODELETE. They need to grow their own DAG,
* which then should have its reference upped separately.
*/
STAILQ_FOREACH(elm, &root->dagmembers, link) {
if (elm->obj != NULL && elm->obj->z_nodelete &&
!elm->obj->ref_nodel) {
dbg("obj %s nodelete", elm->obj->path);
init_dag(elm->obj);
ref_dag(elm->obj);
elm->obj->ref_nodel = true;
}
}
}
/*
* Initialize the dynamic linker. The argument is the address at which
* the dynamic linker has been mapped into memory. The primary task of
* this function is to relocate the dynamic linker.
*/
static void
init_rtld(caddr_t mapbase, Elf_Auxinfo **aux_info)
{
Obj_Entry objtmp; /* Temporary rtld object */
const Elf_Dyn *dyn_rpath;
const Elf_Dyn *dyn_soname;
const Elf_Dyn *dyn_runpath;
/*
* Conjure up an Obj_Entry structure for the dynamic linker.
*
* The "path" member can't be initialized yet because string constants
* cannot yet be accessed. Below we will set it correctly.
*/
memset(&objtmp, 0, sizeof(objtmp));
objtmp.path = NULL;
objtmp.rtld = true;
objtmp.mapbase = mapbase;
#ifdef PIC
objtmp.relocbase = mapbase;
#endif
if (RTLD_IS_DYNAMIC()) {
objtmp.dynamic = rtld_dynamic(&objtmp);
digest_dynamic1(&objtmp, 1, &dyn_rpath, &dyn_soname, &dyn_runpath);
assert(objtmp.needed == NULL);
#if !defined(__mips__)
/* MIPS has a bogus DT_TEXTREL. */
assert(!objtmp.textrel);
#endif
/*
* Temporarily put the dynamic linker entry into the object list, so
* that symbols can be found.
*/
relocate_objects(&objtmp, true, &objtmp, 0, NULL);
}
/* Initialize the object list. */
obj_tail = &obj_list;
/* Now that non-local variables can be accesses, copy out obj_rtld. */
memcpy(&obj_rtld, &objtmp, sizeof(obj_rtld));
if (aux_info[AT_PAGESZ] != NULL)
pagesize = aux_info[AT_PAGESZ]->a_un.a_val;
if (aux_info[AT_OSRELDATE] != NULL)
osreldate = aux_info[AT_OSRELDATE]->a_un.a_val;
digest_dynamic2(&obj_rtld, dyn_rpath, dyn_soname, dyn_runpath);
/* Replace the path with a dynamically allocated copy. */
obj_rtld.path = xstrdup(PATH_RTLD);
r_debug.r_brk = r_debug_state;
r_debug.r_state = RT_CONSISTENT;
}
/*
* Add the init functions from a needed object list (and its recursive
* needed objects) to "list". This is not used directly; it is a helper
* function for initlist_add_objects(). The write lock must be held
* when this function is called.
*/
static void
initlist_add_neededs(Needed_Entry *needed, Objlist *list)
{
/* Recursively process the successor needed objects. */
if (needed->next != NULL)
initlist_add_neededs(needed->next, list);
/* Process the current needed object. */
if (needed->obj != NULL)
initlist_add_objects(needed->obj, &needed->obj->next, list);
}
/*
* Scan all of the DAGs rooted in the range of objects from "obj" to
* "tail" and add their init functions to "list". This recurses over
* the DAGs and ensure the proper init ordering such that each object's
* needed libraries are initialized before the object itself. At the
* same time, this function adds the objects to the global finalization
* list "list_fini" in the opposite order. The write lock must be
* held when this function is called.
*/
static void
initlist_add_objects(Obj_Entry *obj, Obj_Entry **tail, Objlist *list)
{
if (obj->init_scanned || obj->init_done)
return;
obj->init_scanned = true;
/* Recursively process the successor objects. */
if (&obj->next != tail)
initlist_add_objects(obj->next, tail, list);
/* Recursively process the needed objects. */
if (obj->needed != NULL)
initlist_add_neededs(obj->needed, list);
if (obj->needed_filtees != NULL)
initlist_add_neededs(obj->needed_filtees, list);
if (obj->needed_aux_filtees != NULL)
initlist_add_neededs(obj->needed_aux_filtees, list);
/* Add the object to the init list. */
if (obj->preinit_array != (Elf_Addr)NULL || obj->init != (Elf_Addr)NULL ||
obj->init_array != (Elf_Addr)NULL)
objlist_push_tail(list, obj);
/* Add the object to the global fini list in the reverse order. */
if ((obj->fini != (Elf_Addr)NULL || obj->fini_array != (Elf_Addr)NULL)
&& !obj->on_fini_list) {
objlist_push_head(&list_fini, obj);
obj->on_fini_list = true;
}
}
#ifndef FPTR_TARGET
#define FPTR_TARGET(f) ((Elf_Addr) (f))
#endif
static void
free_needed_filtees(Needed_Entry *n)
{
Needed_Entry *needed, *needed1;
for (needed = n; needed != NULL; needed = needed->next) {
if (needed->obj != NULL) {
dlclose(needed->obj);
needed->obj = NULL;
}
}
for (needed = n; needed != NULL; needed = needed1) {
needed1 = needed->next;
free(needed);
}
}
static void
unload_filtees(Obj_Entry *obj)
{
free_needed_filtees(obj->needed_filtees);
obj->needed_filtees = NULL;
free_needed_filtees(obj->needed_aux_filtees);
obj->needed_aux_filtees = NULL;
obj->filtees_loaded = false;
}
static void
load_filtee1(Obj_Entry *obj, Needed_Entry *needed, int flags,
RtldLockState *lockstate)
{
for (; needed != NULL; needed = needed->next) {
needed->obj = dlopen_object(obj->strtab + needed->name, -1, obj,
flags, ((ld_loadfltr || obj->z_loadfltr) ? RTLD_NOW : RTLD_LAZY) |
RTLD_LOCAL, lockstate);
}
}
static void
load_filtees(Obj_Entry *obj, int flags, RtldLockState *lockstate)
{
lock_restart_for_upgrade(lockstate);
if (!obj->filtees_loaded) {
load_filtee1(obj, obj->needed_filtees, flags, lockstate);
load_filtee1(obj, obj->needed_aux_filtees, flags, lockstate);
obj->filtees_loaded = true;
}
}
static int
process_needed(Obj_Entry *obj, Needed_Entry *needed, int flags)
{
Obj_Entry *obj1;
for (; needed != NULL; needed = needed->next) {
obj1 = needed->obj = load_object(obj->strtab + needed->name, -1, obj,
flags & ~RTLD_LO_NOLOAD);
if (obj1 == NULL && !ld_tracing && (flags & RTLD_LO_FILTEES) == 0)
return (-1);
}
return (0);
}
/*
* Given a shared object, traverse its list of needed objects, and load
* each of them. Returns 0 on success. Generates an error message and
* returns -1 on failure.
*/
static int
load_needed_objects(Obj_Entry *first, int flags)
{
Obj_Entry *obj;
for (obj = first; obj != NULL; obj = obj->next) {
if (process_needed(obj, obj->needed, flags) == -1)
return (-1);
}
return (0);
}
static int
load_preload_objects(void)
{
char *p = ld_preload;
Obj_Entry *obj;
static const char delim[] = " \t:;";
if (p == NULL)
return 0;
p += strspn(p, delim);
while (*p != '\0') {
size_t len = strcspn(p, delim);
char savech;
savech = p[len];
p[len] = '\0';
obj = load_object(p, -1, NULL, 0);
if (obj == NULL)
return -1; /* XXX - cleanup */
obj->z_interpose = true;
p[len] = savech;
p += len;
p += strspn(p, delim);
}
LD_UTRACE(UTRACE_PRELOAD_FINISHED, NULL, NULL, 0, 0, NULL);
return 0;
}
static const char *
printable_path(const char *path)
{
return (path == NULL ? "<unknown>" : path);
}
/*
* Load a shared object into memory, if it is not already loaded. The
* object may be specified by name or by user-supplied file descriptor
* fd_u. In the later case, the fd_u descriptor is not closed, but its
* duplicate is.
*
* Returns a pointer to the Obj_Entry for the object. Returns NULL
* on failure.
*/
static Obj_Entry *
load_object(const char *name, int fd_u, const Obj_Entry *refobj, int flags)
{
Obj_Entry *obj;
int fd;
struct stat sb;
char *path;
if (name != NULL) {
for (obj = obj_list->next; obj != NULL; obj = obj->next) {
if (object_match_name(obj, name))
return (obj);
}
path = find_library(name, refobj);
if (path == NULL)
return (NULL);
} else
path = NULL;
/*
* If we didn't find a match by pathname, or the name is not
* supplied, open the file and check again by device and inode.
* This avoids false mismatches caused by multiple links or ".."
* in pathnames.
*
* To avoid a race, we open the file and use fstat() rather than
* using stat().
*/
fd = -1;
if (fd_u == -1) {
if ((fd = open(path, O_RDONLY | O_CLOEXEC)) == -1) {
_rtld_error("Cannot open \"%s\"", path);
free(path);
return (NULL);
}
} else {
fd = fcntl(fd_u, F_DUPFD_CLOEXEC, 0);
if (fd == -1) {
_rtld_error("Cannot dup fd");
free(path);
return (NULL);
}
}
if (fstat(fd, &sb) == -1) {
_rtld_error("Cannot fstat \"%s\"", printable_path(path));
close(fd);
free(path);
return NULL;
}
for (obj = obj_list->next; obj != NULL; obj = obj->next)
if (obj->ino == sb.st_ino && obj->dev == sb.st_dev)
break;
if (obj != NULL && name != NULL) {
object_add_name(obj, name);
free(path);
close(fd);
return obj;
}
if (flags & RTLD_LO_NOLOAD) {
free(path);
close(fd);
return (NULL);
}
/* First use of this object, so we must map it in */
obj = do_load_object(fd, name, path, &sb, flags);
if (obj == NULL)
free(path);
close(fd);
return obj;
}
static Obj_Entry *
do_load_object(int fd, const char *name, char *path, struct stat *sbp,
int flags)
{
Obj_Entry *obj;
struct statfs fs;
/*
* but first, make sure that environment variables haven't been
* used to circumvent the noexec flag on a filesystem.
*/
if (dangerous_ld_env) {
if (fstatfs(fd, &fs) != 0) {
_rtld_error("Cannot fstatfs \"%s\"", printable_path(path));
return NULL;
}
if (fs.f_flags & MNT_NOEXEC) {
_rtld_error("Cannot execute objects on %s\n", fs.f_mntonname);
return NULL;
}
}
dbg("loading \"%s\"", printable_path(path));
obj = map_object(fd, printable_path(path), sbp);
if (obj == NULL)
return NULL;
/*
* If DT_SONAME is present in the object, digest_dynamic2 already
* added it to the object names.
*/
if (name != NULL)
object_add_name(obj, name);
obj->path = path;
digest_dynamic(obj, 0);
dbg("%s valid_hash_sysv %d valid_hash_gnu %d dynsymcount %d", obj->path,
obj->valid_hash_sysv, obj->valid_hash_gnu, obj->dynsymcount);
if (obj->z_noopen && (flags & (RTLD_LO_DLOPEN | RTLD_LO_TRACE)) ==
RTLD_LO_DLOPEN) {
dbg("refusing to load non-loadable \"%s\"", obj->path);
_rtld_error("Cannot dlopen non-loadable %s", obj->path);
munmap(obj->mapbase, obj->mapsize);
obj_free(obj);
return (NULL);
}
*obj_tail = obj;
obj_tail = &obj->next;
obj_count++;
obj_loads++;
linkmap_add(obj); /* for GDB & dlinfo() */
max_stack_flags |= obj->stack_flags;
dbg(" %p .. %p: %s", obj->mapbase,
obj->mapbase + obj->mapsize - 1, obj->path);
if (obj->textrel)
dbg(" WARNING: %s has impure text", obj->path);
LD_UTRACE(UTRACE_LOAD_OBJECT, obj, obj->mapbase, obj->mapsize, 0,
obj->path);
return obj;
}
static Obj_Entry *
obj_from_addr(const void *addr)
{
Obj_Entry *obj;
for (obj = obj_list; obj != NULL; obj = obj->next) {
if (addr < (void *) obj->mapbase)
continue;
if (addr < (void *) (obj->mapbase + obj->mapsize))
return obj;
}
return NULL;
}
static void
preinit_main(void)
{
Elf_Addr *preinit_addr;
int index;
preinit_addr = (Elf_Addr *)obj_main->preinit_array;
if (preinit_addr == NULL)
return;
for (index = 0; index < obj_main->preinit_array_num; index++) {
if (preinit_addr[index] != 0 && preinit_addr[index] != 1) {
dbg("calling preinit function for %s at %p", obj_main->path,
(void *)preinit_addr[index]);
LD_UTRACE(UTRACE_INIT_CALL, obj_main, (void *)preinit_addr[index],
0, 0, obj_main->path);
call_init_pointer(obj_main, preinit_addr[index]);
}
}
}
/*
* Call the finalization functions for each of the objects in "list"
* belonging to the DAG of "root" and referenced once. If NULL "root"
* is specified, every finalization function will be called regardless
* of the reference count and the list elements won't be freed. All of
* the objects are expected to have non-NULL fini functions.
*/
static void
objlist_call_fini(Objlist *list, Obj_Entry *root, RtldLockState *lockstate)
{
Objlist_Entry *elm;
char *saved_msg;
Elf_Addr *fini_addr;
int index;
assert(root == NULL || root->refcount == 1);
/*
* Preserve the current error message since a fini function might
* call into the dynamic linker and overwrite it.
*/
saved_msg = errmsg_save();
do {
STAILQ_FOREACH(elm, list, link) {
if (root != NULL && (elm->obj->refcount != 1 ||
objlist_find(&root->dagmembers, elm->obj) == NULL))
continue;
/* Remove object from fini list to prevent recursive invocation. */
STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
/*
* XXX: If a dlopen() call references an object while the
* fini function is in progress, we might end up trying to
* unload the referenced object in dlclose() or the object
* won't be unloaded although its fini function has been
* called.
*/
lock_release(rtld_bind_lock, lockstate);
/*
* It is legal to have both DT_FINI and DT_FINI_ARRAY defined.
* When this happens, DT_FINI_ARRAY is processed first.
*/
fini_addr = (Elf_Addr *)elm->obj->fini_array;
if (fini_addr != NULL && elm->obj->fini_array_num > 0) {
for (index = elm->obj->fini_array_num - 1; index >= 0;
index--) {
if (fini_addr[index] != 0 && fini_addr[index] != 1) {
dbg("calling fini function for %s at %p",
elm->obj->path, (void *)fini_addr[index]);
LD_UTRACE(UTRACE_FINI_CALL, elm->obj,
(void *)fini_addr[index], 0, 0, elm->obj->path);
call_initfini_pointer(elm->obj, fini_addr[index]);
}
}
}
if (elm->obj->fini != (Elf_Addr)NULL) {
dbg("calling fini function for %s at %p", elm->obj->path,
(void *)elm->obj->fini);
LD_UTRACE(UTRACE_FINI_CALL, elm->obj, (void *)elm->obj->fini,
0, 0, elm->obj->path);
call_initfini_pointer(elm->obj, elm->obj->fini);
}
wlock_acquire(rtld_bind_lock, lockstate);
/* No need to free anything if process is going down. */
if (root != NULL)
free(elm);
/*
* We must restart the list traversal after every fini call
* because a dlclose() call from the fini function or from
* another thread might have modified the reference counts.
*/
break;
}
} while (elm != NULL);
errmsg_restore(saved_msg);
}
/*
* Call the initialization functions for each of the objects in
* "list". All of the objects are expected to have non-NULL init
* functions.
*/
static void
objlist_call_init(Objlist *list, RtldLockState *lockstate)
{
Objlist_Entry *elm;
Obj_Entry *obj;
char *saved_msg;
Elf_Addr *init_addr;
int index;
/*
* Clean init_scanned flag so that objects can be rechecked and
* possibly initialized earlier if any of vectors called below
* cause the change by using dlopen.
*/
for (obj = obj_list; obj != NULL; obj = obj->next)
obj->init_scanned = false;
/*
* Preserve the current error message since an init function might
* call into the dynamic linker and overwrite it.
*/
saved_msg = errmsg_save();
STAILQ_FOREACH(elm, list, link) {
if (elm->obj->init_done) /* Initialized early. */
continue;
/*
* Race: other thread might try to use this object before current
* one completes the initilization. Not much can be done here
* without better locking.
*/
elm->obj->init_done = true;
lock_release(rtld_bind_lock, lockstate);
/*
* It is legal to have both DT_INIT and DT_INIT_ARRAY defined.
* When this happens, DT_INIT is processed first.
*/
if (elm->obj->init != (Elf_Addr)NULL) {
dbg("calling init function for %s at %p", elm->obj->path,
(void *)elm->obj->init);
LD_UTRACE(UTRACE_INIT_CALL, elm->obj, (void *)elm->obj->init,
0, 0, elm->obj->path);
call_initfini_pointer(elm->obj, elm->obj->init);
}
init_addr = (Elf_Addr *)elm->obj->init_array;
if (init_addr != NULL) {
for (index = 0; index < elm->obj->init_array_num; index++) {
if (init_addr[index] != 0 && init_addr[index] != 1) {
dbg("calling init function for %s at %p", elm->obj->path,
(void *)init_addr[index]);
LD_UTRACE(UTRACE_INIT_CALL, elm->obj,
(void *)init_addr[index], 0, 0, elm->obj->path);
call_init_pointer(elm->obj, init_addr[index]);
}
}
}
wlock_acquire(rtld_bind_lock, lockstate);
}
errmsg_restore(saved_msg);
}
static void
objlist_clear(Objlist *list)
{
Objlist_Entry *elm;
while (!STAILQ_EMPTY(list)) {
elm = STAILQ_FIRST(list);
STAILQ_REMOVE_HEAD(list, link);
free(elm);
}
}
static Objlist_Entry *
objlist_find(Objlist *list, const Obj_Entry *obj)
{
Objlist_Entry *elm;
STAILQ_FOREACH(elm, list, link)
if (elm->obj == obj)
return elm;
return NULL;
}
static void
objlist_init(Objlist *list)
{
STAILQ_INIT(list);
}
static void
objlist_push_head(Objlist *list, Obj_Entry *obj)
{
Objlist_Entry *elm;
elm = NEW(Objlist_Entry);
elm->obj = obj;
STAILQ_INSERT_HEAD(list, elm, link);
}
static void
objlist_push_tail(Objlist *list, Obj_Entry *obj)
{
Objlist_Entry *elm;
elm = NEW(Objlist_Entry);
elm->obj = obj;
STAILQ_INSERT_TAIL(list, elm, link);
}
static void
objlist_put_after(Objlist *list, Obj_Entry *listobj, Obj_Entry *obj)
{
Objlist_Entry *elm, *listelm;
STAILQ_FOREACH(listelm, list, link) {
if (listelm->obj == listobj)
break;
}
elm = NEW(Objlist_Entry);
elm->obj = obj;
if (listelm != NULL)
STAILQ_INSERT_AFTER(list, listelm, elm, link);
else
STAILQ_INSERT_TAIL(list, elm, link);
}
static void
objlist_remove(Objlist *list, Obj_Entry *obj)
{
Objlist_Entry *elm;
if ((elm = objlist_find(list, obj)) != NULL) {
STAILQ_REMOVE(list, elm, Struct_Objlist_Entry, link);
free(elm);
}
}
/*
* Relocate dag rooted in the specified object.
* Returns 0 on success, or -1 on failure.
*/
static int
relocate_object_dag(Obj_Entry *root, bool bind_now, Obj_Entry *rtldobj,
int flags, RtldLockState *lockstate)
{
Objlist_Entry *elm;
int error;
error = 0;
STAILQ_FOREACH(elm, &root->dagmembers, link) {
error = relocate_object(elm->obj, bind_now, rtldobj, flags,
lockstate);
if (error == -1)
break;
}
return (error);
}
/*
* Relocate single object.
* Returns 0 on success, or -1 on failure.
*/
static int
relocate_object(Obj_Entry *obj, bool bind_now, Obj_Entry *rtldobj,
int flags, RtldLockState *lockstate)
{
if (obj->relocated)
return (0);
obj->relocated = true;
if (obj != rtldobj)
dbg("relocating \"%s\"", obj->path);
if (obj->symtab == NULL || obj->strtab == NULL ||
!(obj->valid_hash_sysv || obj->valid_hash_gnu)) {
_rtld_error("%s: Shared object has no run-time symbol table",
obj->path);
return (-1);
}
if (obj->textrel) {
/* There are relocations to the write-protected text segment. */
if (mprotect(obj->mapbase, obj->textsize,
PROT_READ|PROT_WRITE|PROT_EXEC) == -1) {
_rtld_error("%s: Cannot write-enable text segment: %s",
obj->path, rtld_strerror(errno));
return (-1);
}
}
/* Process the non-PLT relocations. */
if (reloc_non_plt(obj, rtldobj, flags, lockstate))
return (-1);
if (obj->textrel) { /* Re-protected the text segment. */
if (mprotect(obj->mapbase, obj->textsize,
PROT_READ|PROT_EXEC) == -1) {
_rtld_error("%s: Cannot write-protect text segment: %s",
obj->path, rtld_strerror(errno));
return (-1);
}
}
/* Set the special PLT or GOT entries. */
init_pltgot(obj);
/* Process the PLT relocations. */
if (reloc_plt(obj) == -1)
return (-1);
/* Relocate the jump slots if we are doing immediate binding. */
if (obj->bind_now || bind_now)
if (reloc_jmpslots(obj, flags, lockstate) == -1)
return (-1);
if (obj->relro_size > 0) {
if (mprotect(obj->relro_page, obj->relro_size,
PROT_READ) == -1) {
_rtld_error("%s: Cannot enforce relro protection: %s",
obj->path, rtld_strerror(errno));
return (-1);
}
}
/*
* Set up the magic number and version in the Obj_Entry. These
* were checked in the crt1.o from the original ElfKit, so we
* set them for backward compatibility.
*/
obj->magic = RTLD_MAGIC;
obj->version = RTLD_VERSION;
return (0);
}
/*
* Relocate newly-loaded shared objects. The argument is a pointer to
* the Obj_Entry for the first such object. All objects from the first
* to the end of the list of objects are relocated. Returns 0 on success,
* or -1 on failure.
*/
static int
relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj,
int flags, RtldLockState *lockstate)
{
Obj_Entry *obj;
int error;
for (error = 0, obj = first; obj != NULL; obj = obj->next) {
error = relocate_object(obj, bind_now, rtldobj, flags,
lockstate);
if (error == -1)
break;
}
return (error);
}
/*
* The handling of R_MACHINE_IRELATIVE relocations and jumpslots
* referencing STT_GNU_IFUNC symbols is postponed till the other
* relocations are done. The indirect functions specified as
* ifunc are allowed to call other symbols, so we need to have
* objects relocated before asking for resolution from indirects.
*
* The R_MACHINE_IRELATIVE slots are resolved in greedy fashion,
* instead of the usual lazy handling of PLT slots. It is
* consistent with how GNU does it.
*/
static int
resolve_object_ifunc(Obj_Entry *obj, bool bind_now, int flags,
RtldLockState *lockstate)
{
if (obj->irelative && reloc_iresolve(obj, lockstate) == -1)
return (-1);
if ((obj->bind_now || bind_now) && obj->gnu_ifunc &&
reloc_gnu_ifunc(obj, flags, lockstate) == -1)
return (-1);
return (0);
}
static int
resolve_objects_ifunc(Obj_Entry *first, bool bind_now, int flags,
RtldLockState *lockstate)
{
Obj_Entry *obj;
for (obj = first; obj != NULL; obj = obj->next) {
if (resolve_object_ifunc(obj, bind_now, flags, lockstate) == -1)
return (-1);
}
return (0);
}
static int
initlist_objects_ifunc(Objlist *list, bool bind_now, int flags,
RtldLockState *lockstate)
{
Objlist_Entry *elm;
STAILQ_FOREACH(elm, list, link) {
if (resolve_object_ifunc(elm->obj, bind_now, flags,
lockstate) == -1)
return (-1);
}
return (0);
}
/*
* Cleanup procedure. It will be called (by the atexit mechanism) just
* before the process exits.
*/
static void
rtld_exit(void)
{
RtldLockState lockstate;
wlock_acquire(rtld_bind_lock, &lockstate);
dbg("rtld_exit()");
objlist_call_fini(&list_fini, NULL, &lockstate);
/* No need to remove the items from the list, since we are exiting. */
if (!libmap_disable)
lm_fini();
lock_release(rtld_bind_lock, &lockstate);
}
/*
* Iterate over a search path, translate each element, and invoke the
* callback on the result.
*/
static void *
path_enumerate(const char *path, path_enum_proc callback, void *arg)
{
const char *trans;
if (path == NULL)
return (NULL);
path += strspn(path, ":;");
while (*path != '\0') {
size_t len;
char *res;
len = strcspn(path, ":;");
trans = lm_findn(NULL, path, len);
if (trans)
res = callback(trans, strlen(trans), arg);
else
res = callback(path, len, arg);
if (res != NULL)
return (res);
path += len;
path += strspn(path, ":;");
}
return (NULL);
}
struct try_library_args {
const char *name;
size_t namelen;
char *buffer;
size_t buflen;
};
static void *
try_library_path(const char *dir, size_t dirlen, void *param)
{
struct try_library_args *arg;
arg = param;
if (*dir == '/' || trust) {
char *pathname;
if (dirlen + 1 + arg->namelen + 1 > arg->buflen)
return (NULL);
pathname = arg->buffer;
strncpy(pathname, dir, dirlen);
pathname[dirlen] = '/';
strcpy(pathname + dirlen + 1, arg->name);
dbg(" Trying \"%s\"", pathname);
if (access(pathname, F_OK) == 0) { /* We found it */
pathname = xmalloc(dirlen + 1 + arg->namelen + 1);
strcpy(pathname, arg->buffer);
return (pathname);
}
}
return (NULL);
}
static char *
search_library_path(const char *name, const char *path)
{
char *p;
struct try_library_args arg;
if (path == NULL)
return NULL;
arg.name = name;
arg.namelen = strlen(name);
arg.buffer = xmalloc(PATH_MAX);
arg.buflen = PATH_MAX;
p = path_enumerate(path, try_library_path, &arg);
free(arg.buffer);
return (p);
}
int
dlclose(void *handle)
{
Obj_Entry *root;
RtldLockState lockstate;
wlock_acquire(rtld_bind_lock, &lockstate);
root = dlcheck(handle);
if (root == NULL) {
lock_release(rtld_bind_lock, &lockstate);
return -1;
}
LD_UTRACE(UTRACE_DLCLOSE_START, handle, NULL, 0, root->dl_refcount,
root->path);
/* Unreference the object and its dependencies. */
root->dl_refcount--;
if (root->refcount == 1) {
/*
* The object will be no longer referenced, so we must unload it.
* First, call the fini functions.
*/
objlist_call_fini(&list_fini, root, &lockstate);
unref_dag(root);
/* Finish cleaning up the newly-unreferenced objects. */
GDB_STATE(RT_DELETE,&root->linkmap);
unload_object(root);
GDB_STATE(RT_CONSISTENT,NULL);
} else
unref_dag(root);
LD_UTRACE(UTRACE_DLCLOSE_STOP, handle, NULL, 0, 0, NULL);
lock_release(rtld_bind_lock, &lockstate);
return 0;
}
char *
dlerror(void)
{
char *msg = error_message;
error_message = NULL;
return msg;
}
/*
* This function is deprecated and has no effect.
*/
void
dllockinit(void *context,
void *(*lock_create)(void *context),
void (*rlock_acquire)(void *lock),
void (*wlock_acquire)(void *lock),
void (*lock_release)(void *lock),
void (*lock_destroy)(void *lock),
void (*context_destroy)(void *context))
{
static void *cur_context;
static void (*cur_context_destroy)(void *);
/* Just destroy the context from the previous call, if necessary. */
if (cur_context_destroy != NULL)
cur_context_destroy(cur_context);
cur_context = context;
cur_context_destroy = context_destroy;
}
void *
dlopen(const char *name, int mode)
{
return (rtld_dlopen(name, -1, mode));
}
void *
fdlopen(int fd, int mode)
{
return (rtld_dlopen(NULL, fd, mode));
}
static void *
rtld_dlopen(const char *name, int fd, int mode)
{
RtldLockState lockstate;
int lo_flags;
LD_UTRACE(UTRACE_DLOPEN_START, NULL, NULL, 0, mode, name);
ld_tracing = (mode & RTLD_TRACE) == 0 ? NULL : "1";
if (ld_tracing != NULL) {
rlock_acquire(rtld_bind_lock, &lockstate);
if (sigsetjmp(lockstate.env, 0) != 0)
lock_upgrade(rtld_bind_lock, &lockstate);
environ = (char **)*get_program_var_addr("environ", &lockstate);
lock_release(rtld_bind_lock, &lockstate);
}
lo_flags = RTLD_LO_DLOPEN;
if (mode & RTLD_NODELETE)
lo_flags |= RTLD_LO_NODELETE;
if (mode & RTLD_NOLOAD)
lo_flags |= RTLD_LO_NOLOAD;
if (ld_tracing != NULL)
lo_flags |= RTLD_LO_TRACE;
return (dlopen_object(name, fd, obj_main, lo_flags,
mode & (RTLD_MODEMASK | RTLD_GLOBAL), NULL));
}
static void
dlopen_cleanup(Obj_Entry *obj)
{
obj->dl_refcount--;
unref_dag(obj);
if (obj->refcount == 0)
unload_object(obj);
}
static Obj_Entry *
dlopen_object(const char *name, int fd, Obj_Entry *refobj, int lo_flags,
int mode, RtldLockState *lockstate)
{
Obj_Entry **old_obj_tail;
Obj_Entry *obj;
Objlist initlist;
RtldLockState mlockstate;
int result;
objlist_init(&initlist);
if (lockstate == NULL && !(lo_flags & RTLD_LO_EARLY)) {
wlock_acquire(rtld_bind_lock, &mlockstate);
lockstate = &mlockstate;
}
GDB_STATE(RT_ADD,NULL);
old_obj_tail = obj_tail;
obj = NULL;
if (name == NULL && fd == -1) {
obj = obj_main;
obj->refcount++;
} else {
obj = load_object(name, fd, refobj, lo_flags);
}
if (obj) {
obj->dl_refcount++;
if (mode & RTLD_GLOBAL && objlist_find(&list_global, obj) == NULL)
objlist_push_tail(&list_global, obj);
if (*old_obj_tail != NULL) { /* We loaded something new. */
assert(*old_obj_tail == obj);
result = load_needed_objects(obj,
lo_flags & (RTLD_LO_DLOPEN | RTLD_LO_EARLY));
init_dag(obj);
ref_dag(obj);
if (result != -1)
result = rtld_verify_versions(&obj->dagmembers);
if (result != -1 && ld_tracing)
goto trace;
if (result == -1 || relocate_object_dag(obj,
(mode & RTLD_MODEMASK) == RTLD_NOW, &obj_rtld,
(lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
lockstate) == -1) {
dlopen_cleanup(obj);
obj = NULL;
} else if (lo_flags & RTLD_LO_EARLY) {
/*
* Do not call the init functions for early loaded
* filtees. The image is still not initialized enough
* for them to work.
*
* Our object is found by the global object list and
* will be ordered among all init calls done right
* before transferring control to main.
*/
} else {
/* Make list of init functions to call. */
initlist_add_objects(obj, &obj->next, &initlist);
}
/*
* Process all no_delete objects here, given them own
* DAGs to prevent their dependencies from being unloaded.
* This has to be done after we have loaded all of the
* dependencies, so that we do not miss any.
*/
if (obj != NULL)
process_nodelete(obj);
} else {
/*
* Bump the reference counts for objects on this DAG. If
* this is the first dlopen() call for the object that was
* already loaded as a dependency, initialize the dag
* starting at it.
*/
init_dag(obj);
ref_dag(obj);
if ((lo_flags & RTLD_LO_TRACE) != 0)
goto trace;
}
if (obj != NULL && ((lo_flags & RTLD_LO_NODELETE) != 0 ||
obj->z_nodelete) && !obj->ref_nodel) {
dbg("obj %s nodelete", obj->path);
ref_dag(obj);
obj->z_nodelete = obj->ref_nodel = true;
}
}
LD_UTRACE(UTRACE_DLOPEN_STOP, obj, NULL, 0, obj ? obj->dl_refcount : 0,
name);
GDB_STATE(RT_CONSISTENT,obj ? &obj->linkmap : NULL);
if (!(lo_flags & RTLD_LO_EARLY)) {
map_stacks_exec(lockstate);
}
if (initlist_objects_ifunc(&initlist, (mode & RTLD_MODEMASK) == RTLD_NOW,
(lo_flags & RTLD_LO_EARLY) ? SYMLOOK_EARLY : 0,
lockstate) == -1) {
objlist_clear(&initlist);
dlopen_cleanup(obj);
if (lockstate == &mlockstate)
lock_release(rtld_bind_lock, lockstate);
return (NULL);
}
if (!(lo_flags & RTLD_LO_EARLY)) {
/* Call the init functions. */
objlist_call_init(&initlist, lockstate);
}
objlist_clear(&initlist);
if (lockstate == &mlockstate)
lock_release(rtld_bind_lock, lockstate);
return obj;
trace:
trace_loaded_objects(obj);
if (lockstate == &mlockstate)
lock_release(rtld_bind_lock, lockstate);
exit(0);
}
static void *
do_dlsym(void *handle, const char *name, void *retaddr, const Ver_Entry *ve,
int flags)
{
DoneList donelist;
const Obj_Entry *obj, *defobj;
const Elf_Sym *def;
SymLook req;
RtldLockState lockstate;
#ifndef __ia64__
tls_index ti;
#endif
int res;
def = NULL;
defobj = NULL;
symlook_init(&req, name);
req.ventry = ve;
req.flags = flags | SYMLOOK_IN_PLT;
req.lockstate = &lockstate;
rlock_acquire(rtld_bind_lock, &lockstate);
if (sigsetjmp(lockstate.env, 0) != 0)
lock_upgrade(rtld_bind_lock, &lockstate);
if (handle == NULL || handle == RTLD_NEXT ||
handle == RTLD_DEFAULT || handle == RTLD_SELF) {
if ((obj = obj_from_addr(retaddr)) == NULL) {
_rtld_error("Cannot determine caller's shared object");
lock_release(rtld_bind_lock, &lockstate);
return NULL;
}
if (handle == NULL) { /* Just the caller's shared object. */
res = symlook_obj(&req, obj);
if (res == 0) {
def = req.sym_out;
defobj = req.defobj_out;
}
} else if (handle == RTLD_NEXT || /* Objects after caller's */
handle == RTLD_SELF) { /* ... caller included */
if (handle == RTLD_NEXT)
obj = obj->next;
for (; obj != NULL; obj = obj->next) {
res = symlook_obj(&req, obj);
if (res == 0) {
if (def == NULL ||
ELF_ST_BIND(req.sym_out->st_info) != STB_WEAK) {
def = req.sym_out;
defobj = req.defobj_out;
if (ELF_ST_BIND(def->st_info) != STB_WEAK)
break;
}
}
}
/*
* Search the dynamic linker itself, and possibly resolve the
* symbol from there. This is how the application links to
* dynamic linker services such as dlopen.
*/
if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
res = symlook_obj(&req, &obj_rtld);
if (res == 0) {
def = req.sym_out;
defobj = req.defobj_out;
}
}
} else {
assert(handle == RTLD_DEFAULT);
res = symlook_default(&req, obj);
if (res == 0) {
defobj = req.defobj_out;
def = req.sym_out;
}
}
} else {
if ((obj = dlcheck(handle)) == NULL) {
lock_release(rtld_bind_lock, &lockstate);
return NULL;
}
donelist_init(&donelist);
if (obj->mainprog) {
/* Handle obtained by dlopen(NULL, ...) implies global scope. */
res = symlook_global(&req, &donelist);
if (res == 0) {
def = req.sym_out;
defobj = req.defobj_out;
}
/*
* Search the dynamic linker itself, and possibly resolve the
* symbol from there. This is how the application links to
* dynamic linker services such as dlopen.
*/
if (def == NULL || ELF_ST_BIND(def->st_info) == STB_WEAK) {
res = symlook_obj(&req, &obj_rtld);
if (res == 0) {
def = req.sym_out;
defobj = req.defobj_out;
}
}
}
else {
/* Search the whole DAG rooted at the given object. */
res = symlook_list(&req, &obj->dagmembers, &donelist);
if (res == 0) {
def = req.sym_out;
defobj = req.defobj_out;
}
}
}
if (def != NULL) {
lock_release(rtld_bind_lock, &lockstate);
/*
* The value required by the caller is derived from the value
* of the symbol. For the ia64 architecture, we need to
* construct a function descriptor which the caller can use to
* call the function with the right 'gp' value. For other
* architectures and for non-functions, the value is simply
* the relocated value of the symbol.
*/
if (ELF_ST_TYPE(def->st_info) == STT_FUNC)
return (make_function_pointer(def, defobj));
else if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC)
return (rtld_resolve_ifunc(defobj, def));
else if (ELF_ST_TYPE(def->st_info) == STT_TLS) {
#ifdef __ia64__
return (__tls_get_addr(defobj->tlsindex, def->st_value));
#else
ti.ti_module = defobj->tlsindex;
ti.ti_offset = def->st_value;
return (__tls_get_addr(&ti));
#endif
} else
return (defobj->relocbase + def->st_value);
}
_rtld_error("Undefined symbol \"%s\"", name);
lock_release(rtld_bind_lock, &lockstate);
return NULL;
}
void *
dlsym(void *handle, const char *name)
{
return do_dlsym(handle, name, __builtin_return_address(0), NULL,
SYMLOOK_DLSYM);
}
dlfunc_t
dlfunc(void *handle, const char *name)
{
union {
void *d;
dlfunc_t f;
} rv;
rv.d = do_dlsym(handle, name, __builtin_return_address(0), NULL,
SYMLOOK_DLSYM);
return (rv.f);
}
void *
dlvsym(void *handle, const char *name, const char *version)
{
Ver_Entry ventry;
ventry.name = version;
ventry.file = NULL;
ventry.hash = elf_hash(version);
ventry.flags= 0;
return do_dlsym(handle, name, __builtin_return_address(0), &ventry,
SYMLOOK_DLSYM);
}
int
_rtld_addr_phdr(const void *addr, struct dl_phdr_info *phdr_info)
{
const Obj_Entry *obj;
RtldLockState lockstate;
rlock_acquire(rtld_bind_lock, &lockstate);
obj = obj_from_addr(addr);
if (obj == NULL) {
_rtld_error("No shared object contains address");
lock_release(rtld_bind_lock, &lockstate);
return (0);
}
rtld_fill_dl_phdr_info(obj, phdr_info);
lock_release(rtld_bind_lock, &lockstate);
return (1);
}
int
dladdr(const void *addr, Dl_info *info)
{
const Obj_Entry *obj;
const Elf_Sym *def;
void *symbol_addr;
unsigned long symoffset;
RtldLockState lockstate;
rlock_acquire(rtld_bind_lock, &lockstate);
obj = obj_from_addr(addr);
if (obj == NULL) {
_rtld_error("No shared object contains address");
lock_release(rtld_bind_lock, &lockstate);
return 0;
}
info->dli_fname = obj->path;
info->dli_fbase = obj->mapbase;
info->dli_saddr = (void *)0;
info->dli_sname = NULL;
/*
* Walk the symbol list looking for the symbol whose address is
* closest to the address sent in.
*/
for (symoffset = 0; symoffset < obj->dynsymcount; symoffset++) {
def = obj->symtab + symoffset;
/*
* For skip the symbol if st_shndx is either SHN_UNDEF or
* SHN_COMMON.
*/
if (def->st_shndx == SHN_UNDEF || def->st_shndx == SHN_COMMON)
continue;
/*
* If the symbol is greater than the specified address, or if it
* is further away from addr than the current nearest symbol,
* then reject it.
*/
symbol_addr = obj->relocbase + def->st_value;
if (symbol_addr > addr || symbol_addr < info->dli_saddr)
continue;
/* Update our idea of the nearest symbol. */
info->dli_sname = obj->strtab + def->st_name;
info->dli_saddr = symbol_addr;
/* Exact match? */
if (info->dli_saddr == addr)
break;
}
lock_release(rtld_bind_lock, &lockstate);
return 1;
}
int
dlinfo(void *handle, int request, void *p)
{
const Obj_Entry *obj;
RtldLockState lockstate;
int error;
rlock_acquire(rtld_bind_lock, &lockstate);
if (handle == NULL || handle == RTLD_SELF) {
void *retaddr;
retaddr = __builtin_return_address(0); /* __GNUC__ only */
if ((obj = obj_from_addr(retaddr)) == NULL)
_rtld_error("Cannot determine caller's shared object");
} else
obj = dlcheck(handle);
if (obj == NULL) {
lock_release(rtld_bind_lock, &lockstate);
return (-1);
}
error = 0;
switch (request) {
case RTLD_DI_LINKMAP:
*((struct link_map const **)p) = &obj->linkmap;
break;
case RTLD_DI_ORIGIN:
error = rtld_dirname(obj->path, p);
break;
case RTLD_DI_SERINFOSIZE:
case RTLD_DI_SERINFO:
error = do_search_info(obj, request, (struct dl_serinfo *)p);
break;
default:
_rtld_error("Invalid request %d passed to dlinfo()", request);
error = -1;
}
lock_release(rtld_bind_lock, &lockstate);
return (error);
}
static void
rtld_fill_dl_phdr_info(const Obj_Entry *obj, struct dl_phdr_info *phdr_info)
{
phdr_info->dlpi_addr = (Elf_Addr)obj->relocbase;
phdr_info->dlpi_name = STAILQ_FIRST(&obj->names) ?
STAILQ_FIRST(&obj->names)->name : obj->path;
phdr_info->dlpi_phdr = obj->phdr;
phdr_info->dlpi_phnum = obj->phsize / sizeof(obj->phdr[0]);
phdr_info->dlpi_tls_modid = obj->tlsindex;
phdr_info->dlpi_tls_data = obj->tlsinit;
phdr_info->dlpi_adds = obj_loads;
phdr_info->dlpi_subs = obj_loads - obj_count;
}
int
dl_iterate_phdr(__dl_iterate_hdr_callback callback, void *param)
{
struct dl_phdr_info phdr_info;
const Obj_Entry *obj;
RtldLockState bind_lockstate, phdr_lockstate;
int error;
wlock_acquire(rtld_phdr_lock, &phdr_lockstate);
rlock_acquire(rtld_bind_lock, &bind_lockstate);
error = 0;
for (obj = obj_list; obj != NULL; obj = obj->next) {
rtld_fill_dl_phdr_info(obj, &phdr_info);
if ((error = callback(&phdr_info, sizeof phdr_info, param)) != 0)
break;
}
lock_release(rtld_bind_lock, &bind_lockstate);
lock_release(rtld_phdr_lock, &phdr_lockstate);
return (error);
}
static void *
fill_search_info(const char *dir, size_t dirlen, void *param)
{
struct fill_search_info_args *arg;
arg = param;
if (arg->request == RTLD_DI_SERINFOSIZE) {
arg->serinfo->dls_cnt ++;
arg->serinfo->dls_size += sizeof(struct dl_serpath) + dirlen + 1;
} else {
struct dl_serpath *s_entry;
s_entry = arg->serpath;
s_entry->dls_name = arg->strspace;
s_entry->dls_flags = arg->flags;
strncpy(arg->strspace, dir, dirlen);
arg->strspace[dirlen] = '\0';
arg->strspace += dirlen + 1;
arg->serpath++;
}
return (NULL);
}
static int
do_search_info(const Obj_Entry *obj, int request, struct dl_serinfo *info)
{
struct dl_serinfo _info;
struct fill_search_info_args args;
args.request = RTLD_DI_SERINFOSIZE;
args.serinfo = &_info;
_info.dls_size = __offsetof(struct dl_serinfo, dls_serpath);
_info.dls_cnt = 0;
path_enumerate(obj->rpath, fill_search_info, &args);
path_enumerate(ld_library_path, fill_search_info, &args);
path_enumerate(obj->runpath, fill_search_info, &args);
path_enumerate(gethints(obj->z_nodeflib), fill_search_info, &args);
if (!obj->z_nodeflib)
path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args);
if (request == RTLD_DI_SERINFOSIZE) {
info->dls_size = _info.dls_size;
info->dls_cnt = _info.dls_cnt;
return (0);
}
if (info->dls_cnt != _info.dls_cnt || info->dls_size != _info.dls_size) {
_rtld_error("Uninitialized Dl_serinfo struct passed to dlinfo()");
return (-1);
}
args.request = RTLD_DI_SERINFO;
args.serinfo = info;
args.serpath = &info->dls_serpath[0];
args.strspace = (char *)&info->dls_serpath[_info.dls_cnt];
args.flags = LA_SER_RUNPATH;
if (path_enumerate(obj->rpath, fill_search_info, &args) != NULL)
return (-1);
args.flags = LA_SER_LIBPATH;
if (path_enumerate(ld_library_path, fill_search_info, &args) != NULL)
return (-1);
args.flags = LA_SER_RUNPATH;
if (path_enumerate(obj->runpath, fill_search_info, &args) != NULL)
return (-1);
args.flags = LA_SER_CONFIG;
if (path_enumerate(gethints(obj->z_nodeflib), fill_search_info, &args)
!= NULL)
return (-1);
args.flags = LA_SER_DEFAULT;
if (!obj->z_nodeflib &&
path_enumerate(STANDARD_LIBRARY_PATH, fill_search_info, &args) != NULL)
return (-1);
return (0);
}
static int
rtld_dirname(const char *path, char *bname)
{
const char *endp;
/* Empty or NULL string gets treated as "." */
if (path == NULL || *path == '\0') {
bname[0] = '.';
bname[1] = '\0';
return (0);
}
/* Strip trailing slashes */
endp = path + strlen(path) - 1;
while (endp > path && *endp == '/')
endp--;
/* Find the start of the dir */
while (endp > path && *endp != '/')
endp--;
/* Either the dir is "/" or there are no slashes */
if (endp == path) {
bname[0] = *endp == '/' ? '/' : '.';
bname[1] = '\0';
return (0);
} else {
do {
endp--;
} while (endp > path && *endp == '/');
}
if (endp - path + 2 > PATH_MAX)
{
_rtld_error("Filename is too long: %s", path);
return(-1);
}
strncpy(bname, path, endp - path + 1);
bname[endp - path + 1] = '\0';
return (0);
}
static int
rtld_dirname_abs(const char *path, char *base)
{
char base_rel[PATH_MAX];
if (rtld_dirname(path, base) == -1)
return (-1);
if (base[0] == '/')
return (0);
if (getcwd(base_rel, sizeof(base_rel)) == NULL ||
strlcat(base_rel, "/", sizeof(base_rel)) >= sizeof(base_rel) ||
strlcat(base_rel, base, sizeof(base_rel)) >= sizeof(base_rel))
return (-1);
strcpy(base, base_rel);
return (0);
}
static void
linkmap_add(Obj_Entry *obj)
{
struct link_map *l = &obj->linkmap;
struct link_map *prev;
obj->linkmap.l_name = obj->path;
obj->linkmap.l_addr = obj->mapbase;
obj->linkmap.l_ld = obj->dynamic;
#ifdef __mips__
/* GDB needs load offset on MIPS to use the symbols */
obj->linkmap.l_offs = obj->relocbase;
#endif
if (r_debug.r_map == NULL) {
r_debug.r_map = l;
return;
}
/*
* Scan to the end of the list, but not past the entry for the
* dynamic linker, which we want to keep at the very end.
*/
for (prev = r_debug.r_map;
prev->l_next != NULL && prev->l_next != &obj_rtld.linkmap;
prev = prev->l_next)
;
/* Link in the new entry. */
l->l_prev = prev;
l->l_next = prev->l_next;
if (l->l_next != NULL)
l->l_next->l_prev = l;
prev->l_next = l;
}
static void
linkmap_delete(Obj_Entry *obj)
{
struct link_map *l = &obj->linkmap;
if (l->l_prev == NULL) {
if ((r_debug.r_map = l->l_next) != NULL)
l->l_next->l_prev = NULL;
return;
}
if ((l->l_prev->l_next = l->l_next) != NULL)
l->l_next->l_prev = l->l_prev;
}
/*
* Function for the debugger to set a breakpoint on to gain control.
*
* The two parameters allow the debugger to easily find and determine
* what the runtime loader is doing and to whom it is doing it.
*
* When the loadhook trap is hit (r_debug_state, set at program
* initialization), the arguments can be found on the stack:
*
* +8 struct link_map *m
* +4 struct r_debug *rd
* +0 RetAddr
*/
void
r_debug_state(struct r_debug* rd, struct link_map *m)
{
/*
* The following is a hack to force the compiler to emit calls to
* this function, even when optimizing. If the function is empty,
* the compiler is not obliged to emit any code for calls to it,
* even when marked __noinline. However, gdb depends on those
* calls being made.
*/
__asm __volatile("" : : : "memory");
}
/*
* Get address of the pointer variable in the main program.
* Prefer non-weak symbol over the weak one.
*/
static const void **
get_program_var_addr(const char *name, RtldLockState *lockstate)
{
SymLook req;
DoneList donelist;
symlook_init(&req, name);
req.lockstate = lockstate;
donelist_init(&donelist);
if (symlook_global(&req, &donelist) != 0)
return (NULL);
if (ELF_ST_TYPE(req.sym_out->st_info) == STT_FUNC)
return ((const void **)make_function_pointer(req.sym_out,
req.defobj_out));
else if (ELF_ST_TYPE(req.sym_out->st_info) == STT_GNU_IFUNC)
return ((const void **)rtld_resolve_ifunc(req.defobj_out, req.sym_out));
else
return ((const void **)(req.defobj_out->relocbase +
req.sym_out->st_value));
}
/*
* Set a pointer variable in the main program to the given value. This
* is used to set key variables such as "environ" before any of the
* init functions are called.
*/
static void
set_program_var(const char *name, const void *value)
{
const void **addr;
if ((addr = get_program_var_addr(name, NULL)) != NULL) {
dbg("\"%s\": *%p <-- %p", name, addr, value);
*addr = value;
}
}
/*
* Search the global objects, including dependencies and main object,
* for the given symbol.
*/
static int
symlook_global(SymLook *req, DoneList *donelist)
{
SymLook req1;
const Objlist_Entry *elm;
int res;
symlook_init_from_req(&req1, req);
/* Search all objects loaded at program start up. */
if (req->defobj_out == NULL ||
ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
res = symlook_list(&req1, &list_main, donelist);
if (res == 0 && (req->defobj_out == NULL ||
ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
req->sym_out = req1.sym_out;
req->defobj_out = req1.defobj_out;
assert(req->defobj_out != NULL);
}
}
/* Search all DAGs whose roots are RTLD_GLOBAL objects. */
STAILQ_FOREACH(elm, &list_global, link) {
if (req->defobj_out != NULL &&
ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
break;
res = symlook_list(&req1, &elm->obj->dagmembers, donelist);
if (res == 0 && (req->defobj_out == NULL ||
ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
req->sym_out = req1.sym_out;
req->defobj_out = req1.defobj_out;
assert(req->defobj_out != NULL);
}
}
return (req->sym_out != NULL ? 0 : ESRCH);
}
/*
* Given a symbol name in a referencing object, find the corresponding
* definition of the symbol. Returns a pointer to the symbol, or NULL if
* no definition was found. Returns a pointer to the Obj_Entry of the
* defining object via the reference parameter DEFOBJ_OUT.
*/
static int
symlook_default(SymLook *req, const Obj_Entry *refobj)
{
DoneList donelist;
const Objlist_Entry *elm;
SymLook req1;
int res;
donelist_init(&donelist);
symlook_init_from_req(&req1, req);
/* Look first in the referencing object if linked symbolically. */
if (refobj->symbolic && !donelist_check(&donelist, refobj)) {
res = symlook_obj(&req1, refobj);
if (res == 0) {
req->sym_out = req1.sym_out;
req->defobj_out = req1.defobj_out;
assert(req->defobj_out != NULL);
}
}
symlook_global(req, &donelist);
/* Search all dlopened DAGs containing the referencing object. */
STAILQ_FOREACH(elm, &refobj->dldags, link) {
if (req->sym_out != NULL &&
ELF_ST_BIND(req->sym_out->st_info) != STB_WEAK)
break;
res = symlook_list(&req1, &elm->obj->dagmembers, &donelist);
if (res == 0 && (req->sym_out == NULL ||
ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK)) {
req->sym_out = req1.sym_out;
req->defobj_out = req1.defobj_out;
assert(req->defobj_out != NULL);
}
}
/*
* Search the dynamic linker itself, and possibly resolve the
* symbol from there. This is how the application links to
* dynamic linker services such as dlopen.
*/
if (req->sym_out == NULL ||
ELF_ST_BIND(req->sym_out->st_info) == STB_WEAK) {
res = symlook_obj(&req1, &obj_rtld);
if (res == 0) {
req->sym_out = req1.sym_out;
req->defobj_out = req1.defobj_out;
assert(req->defobj_out != NULL);
}
}
return (req->sym_out != NULL ? 0 : ESRCH);
}
static int
symlook_list(SymLook *req, const Objlist *objlist, DoneList *dlp)
{
const Elf_Sym *def;
const Obj_Entry *defobj;
const Objlist_Entry *elm;
SymLook req1;
int res;
def = NULL;
defobj = NULL;
STAILQ_FOREACH(elm, objlist, link) {
if (donelist_check(dlp, elm->obj))
continue;
symlook_init_from_req(&req1, req);
if ((res = symlook_obj(&req1, elm->obj)) == 0) {
if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
def = req1.sym_out;
defobj = req1.defobj_out;
if (ELF_ST_BIND(def->st_info) != STB_WEAK)
break;
}
}
}
if (def != NULL) {
req->sym_out = def;
req->defobj_out = defobj;
return (0);
}
return (ESRCH);
}
/*
* Search the chain of DAGS cointed to by the given Needed_Entry
* for a symbol of the given name. Each DAG is scanned completely
* before advancing to the next one. Returns a pointer to the symbol,
* or NULL if no definition was found.
*/
static int
symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp)
{
const Elf_Sym *def;
const Needed_Entry *n;
const Obj_Entry *defobj;
SymLook req1;
int res;
def = NULL;
defobj = NULL;
symlook_init_from_req(&req1, req);
for (n = needed; n != NULL; n = n->next) {
if (n->obj == NULL ||
(res = symlook_list(&req1, &n->obj->dagmembers, dlp)) != 0)
continue;
if (def == NULL || ELF_ST_BIND(req1.sym_out->st_info) != STB_WEAK) {
def = req1.sym_out;
defobj = req1.defobj_out;
if (ELF_ST_BIND(def->st_info) != STB_WEAK)
break;
}
}
if (def != NULL) {
req->sym_out = def;
req->defobj_out = defobj;
return (0);
}
return (ESRCH);
}
/*
* Search the symbol table of a single shared object for a symbol of
* the given name and version, if requested. Returns a pointer to the
* symbol, or NULL if no definition was found. If the object is
* filter, return filtered symbol from filtee.
*
* The symbol's hash value is passed in for efficiency reasons; that
* eliminates many recomputations of the hash value.
*/
int
symlook_obj(SymLook *req, const Obj_Entry *obj)
{
DoneList donelist;
SymLook req1;
int flags, res, mres;
/*
* If there is at least one valid hash at this point, we prefer to
* use the faster GNU version if available.
*/
if (obj->valid_hash_gnu)
mres = symlook_obj1_gnu(req, obj);
else if (obj->valid_hash_sysv)
mres = symlook_obj1_sysv(req, obj);
else
return (EINVAL);
if (mres == 0) {
if (obj->needed_filtees != NULL) {
flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
donelist_init(&donelist);
symlook_init_from_req(&req1, req);
res = symlook_needed(&req1, obj->needed_filtees, &donelist);
if (res == 0) {
req->sym_out = req1.sym_out;
req->defobj_out = req1.defobj_out;
}
return (res);
}
if (obj->needed_aux_filtees != NULL) {
flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
donelist_init(&donelist);
symlook_init_from_req(&req1, req);
res = symlook_needed(&req1, obj->needed_aux_filtees, &donelist);
if (res == 0) {
req->sym_out = req1.sym_out;
req->defobj_out = req1.defobj_out;
return (res);
}
}
}
return (mres);
}
/* Symbol match routine common to both hash functions */
static bool
matched_symbol(SymLook *req, const Obj_Entry *obj, Sym_Match_Result *result,
const unsigned long symnum)
{
Elf_Versym verndx;
const Elf_Sym *symp;
const char *strp;
symp = obj->symtab + symnum;
strp = obj->strtab + symp->st_name;
switch (ELF_ST_TYPE(symp->st_info)) {
case STT_FUNC:
case STT_NOTYPE:
case STT_OBJECT:
case STT_COMMON:
case STT_GNU_IFUNC:
if (symp->st_value == 0)
return (false);
/* fallthrough */
case STT_TLS:
if (symp->st_shndx != SHN_UNDEF)
break;
#ifndef __mips__
else if (((req->flags & SYMLOOK_IN_PLT) == 0) &&
(ELF_ST_TYPE(symp->st_info) == STT_FUNC))
break;
/* fallthrough */
#endif
default:
return (false);
}
if (req->name[0] != strp[0] || strcmp(req->name, strp) != 0)
return (false);
if (req->ventry == NULL) {
if (obj->versyms != NULL) {
verndx = VER_NDX(obj->versyms[symnum]);
if (verndx > obj->vernum) {
_rtld_error(
"%s: symbol %s references wrong version %d",
obj->path, obj->strtab + symnum, verndx);
return (false);
}
/*
* If we are not called from dlsym (i.e. this
* is a normal relocation from unversioned
* binary), accept the symbol immediately if
* it happens to have first version after this
* shared object became versioned. Otherwise,
* if symbol is versioned and not hidden,
* remember it. If it is the only symbol with
* this name exported by the shared object, it
* will be returned as a match by the calling
* function. If symbol is global (verndx < 2)
* accept it unconditionally.
*/
if ((req->flags & SYMLOOK_DLSYM) == 0 &&
verndx == VER_NDX_GIVEN) {
result->sym_out = symp;
return (true);
}
else if (verndx >= VER_NDX_GIVEN) {
if ((obj->versyms[symnum] & VER_NDX_HIDDEN)
== 0) {
if (result->vsymp == NULL)
result->vsymp = symp;
result->vcount++;
}
return (false);
}
}
result->sym_out = symp;
return (true);
}
if (obj->versyms == NULL) {
if (object_match_name(obj, req->ventry->name)) {
_rtld_error("%s: object %s should provide version %s "
"for symbol %s", obj_rtld.path, obj->path,
req->ventry->name, obj->strtab + symnum);
return (false);
}
} else {
verndx = VER_NDX(obj->versyms[symnum]);
if (verndx > obj->vernum) {
_rtld_error("%s: symbol %s references wrong version %d",
obj->path, obj->strtab + symnum, verndx);
return (false);
}
if (obj->vertab[verndx].hash != req->ventry->hash ||
strcmp(obj->vertab[verndx].name, req->ventry->name)) {
/*
* Version does not match. Look if this is a
* global symbol and if it is not hidden. If
* global symbol (verndx < 2) is available,
* use it. Do not return symbol if we are
* called by dlvsym, because dlvsym looks for
* a specific version and default one is not
* what dlvsym wants.
*/
if ((req->flags & SYMLOOK_DLSYM) ||
(verndx >= VER_NDX_GIVEN) ||
(obj->versyms[symnum] & VER_NDX_HIDDEN))
return (false);
}
}
result->sym_out = symp;