_rtld_bind() read-locks the bind lock, and possible plt resolution
from the dispatcher would also acquire bind lock in read mode, which is the supported operation. plt is explicitely designed to allow safe multithreaded updates, so the shared lock do not cause problems. The error in r228435 is that it allows read lock acquisition after the write lock for the bind block. If we dlopened the shared object that contains IRELATIVE or jump slot which target is STT_GNU_IFUNC, then possible recursive plt resolve from the dispatcher would cause it. Postpone the resolution for irelative/ifunc right before initializers are called, and drop bind lock around calls to dispatcher. Use initlist to iterate over the objects instead of the ->next, due to drop of the bind lock in iteration. For i386/reloc.c:reloc_iresolve(), fix calculation of the dispatch function address for dso, by taking into account possible non-zero relocbase. MFC after: 3 weeks
This commit is contained in:
parent
7e1f37e14e
commit
5734c46c68
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=228503
@ -413,6 +413,8 @@ reloc_iresolve(Obj_Entry *obj, RtldLockState *lockstate)
|
||||
const Elf_Rela *relalim;
|
||||
const Elf_Rela *rela;
|
||||
|
||||
if (!obj->irelative)
|
||||
return (0);
|
||||
relalim = (const Elf_Rela *)((char *)obj->pltrela + obj->pltrelasize);
|
||||
for (rela = obj->pltrela; rela < relalim; rela++) {
|
||||
Elf_Addr *where, target, *ptr;
|
||||
@ -424,11 +426,14 @@ reloc_iresolve(Obj_Entry *obj, RtldLockState *lockstate)
|
||||
case R_X86_64_IRELATIVE:
|
||||
ptr = (Elf_Addr *)(obj->relocbase + rela->r_addend);
|
||||
where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
|
||||
lock_release(rtld_bind_lock, lockstate);
|
||||
target = ((Elf_Addr (*)(void))ptr)();
|
||||
wlock_acquire(rtld_bind_lock, lockstate);
|
||||
*where = target;
|
||||
break;
|
||||
}
|
||||
}
|
||||
obj->irelative = false;
|
||||
return (0);
|
||||
}
|
||||
|
||||
@ -455,13 +460,15 @@ reloc_gnu_ifunc(Obj_Entry *obj, RtldLockState *lockstate)
|
||||
return (-1);
|
||||
if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC)
|
||||
continue;
|
||||
lock_release(rtld_bind_lock, lockstate);
|
||||
target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
|
||||
wlock_acquire(rtld_bind_lock, lockstate);
|
||||
reloc_jmpslot(where, target, defobj, obj, (const Elf_Rel *)rela);
|
||||
break;
|
||||
}
|
||||
}
|
||||
obj->gnu_ifunc = false;
|
||||
return 0;
|
||||
return (0);
|
||||
}
|
||||
|
||||
void
|
||||
|
@ -371,16 +371,21 @@ reloc_iresolve(Obj_Entry *obj, RtldLockState *lockstate)
|
||||
const Elf_Rel *rel;
|
||||
Elf_Addr *where, target;
|
||||
|
||||
if (!obj->irelative)
|
||||
return (0);
|
||||
rellim = (const Elf_Rel *)((char *)obj->pltrel + obj->pltrelsize);
|
||||
for (rel = obj->pltrel; rel < rellim; rel++) {
|
||||
switch (ELF_R_TYPE(rel->r_info)) {
|
||||
case R_386_IRELATIVE:
|
||||
where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
|
||||
target = ((Elf_Addr (*)(void))(*where))();
|
||||
lock_release(rtld_bind_lock, lockstate);
|
||||
target = ((Elf_Addr (*)(void))(obj->relocbase + *where))();
|
||||
wlock_acquire(rtld_bind_lock, lockstate);
|
||||
*where = target;
|
||||
break;
|
||||
}
|
||||
}
|
||||
obj->irelative = false;
|
||||
return (0);
|
||||
}
|
||||
|
||||
@ -407,7 +412,9 @@ reloc_gnu_ifunc(Obj_Entry *obj, RtldLockState *lockstate)
|
||||
return (-1);
|
||||
if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC)
|
||||
continue;
|
||||
lock_release(rtld_bind_lock, lockstate);
|
||||
target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
|
||||
wlock_acquire(rtld_bind_lock, lockstate);
|
||||
reloc_jmpslot(where, target, defobj, obj, rel);
|
||||
break;
|
||||
}
|
||||
|
@ -116,6 +116,8 @@ static void objlist_push_tail(Objlist *, Obj_Entry *);
|
||||
static void objlist_remove(Objlist *, Obj_Entry *);
|
||||
static void *path_enumerate(const char *, path_enum_proc, void *);
|
||||
static int relocate_objects(Obj_Entry *, bool, Obj_Entry *, RtldLockState *);
|
||||
static int resolve_objects_ifunc(Obj_Entry *first, bool bind_now,
|
||||
RtldLockState *lockstate);
|
||||
static int rtld_dirname(const char *, char *);
|
||||
static int rtld_dirname_abs(const char *, char *);
|
||||
static void rtld_exit(void);
|
||||
@ -513,6 +515,10 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
|
||||
ld_bind_now != NULL && *ld_bind_now != '\0', &obj_rtld, NULL) == -1)
|
||||
die();
|
||||
|
||||
if (resolve_objects_ifunc(obj_main,
|
||||
ld_bind_now != NULL && *ld_bind_now != '\0', NULL) == -1)
|
||||
die();
|
||||
|
||||
dbg("doing copy relocations");
|
||||
if (do_copy_relocations(obj_main) == -1)
|
||||
die();
|
||||
@ -1978,25 +1984,53 @@ relocate_objects(Obj_Entry *first, bool bind_now, Obj_Entry *rtldobj,
|
||||
obj->version = RTLD_VERSION;
|
||||
}
|
||||
|
||||
/*
|
||||
* 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.
|
||||
*/
|
||||
for (obj = first; obj != NULL; obj = obj->next) {
|
||||
return (0);
|
||||
}
|
||||
|
||||
/*
|
||||
* 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, RtldLockState *lockstate)
|
||||
{
|
||||
if (obj->irelative && reloc_iresolve(obj, lockstate) == -1)
|
||||
return (-1);
|
||||
return (-1);
|
||||
if ((obj->bind_now || bind_now) && obj->gnu_ifunc &&
|
||||
reloc_gnu_ifunc(obj, lockstate) == -1)
|
||||
return (-1);
|
||||
}
|
||||
return 0;
|
||||
reloc_gnu_ifunc(obj, lockstate) == -1)
|
||||
return (-1);
|
||||
return (0);
|
||||
}
|
||||
|
||||
static int
|
||||
resolve_objects_ifunc(Obj_Entry *first, bool bind_now, RtldLockState *lockstate)
|
||||
{
|
||||
Obj_Entry *obj;
|
||||
|
||||
for (obj = first; obj != NULL; obj = obj->next) {
|
||||
if (resolve_object_ifunc(obj, bind_now, lockstate) == -1)
|
||||
return (-1);
|
||||
}
|
||||
return (0);
|
||||
}
|
||||
|
||||
static int
|
||||
initlist_objects_ifunc(Objlist *list, bool bind_now, RtldLockState *lockstate)
|
||||
{
|
||||
Objlist_Entry *elm;
|
||||
|
||||
STAILQ_FOREACH(elm, list, link) {
|
||||
if (resolve_object_ifunc(elm->obj, bind_now, lockstate) == -1)
|
||||
return (-1);
|
||||
}
|
||||
return (0);
|
||||
}
|
||||
|
||||
/*
|
||||
@ -2201,6 +2235,16 @@ dlopen(const char *name, int mode)
|
||||
mode & (RTLD_MODEMASK | RTLD_GLOBAL)));
|
||||
}
|
||||
|
||||
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, Obj_Entry *refobj, int lo_flags, int mode)
|
||||
{
|
||||
@ -2239,10 +2283,7 @@ dlopen_object(const char *name, Obj_Entry *refobj, int lo_flags, int mode)
|
||||
goto trace;
|
||||
if (result == -1 || (relocate_objects(obj, (mode & RTLD_MODEMASK)
|
||||
== RTLD_NOW, &obj_rtld, &lockstate)) == -1) {
|
||||
obj->dl_refcount--;
|
||||
unref_dag(obj);
|
||||
if (obj->refcount == 0)
|
||||
unload_object(obj);
|
||||
dlopen_cleanup(obj);
|
||||
obj = NULL;
|
||||
} else {
|
||||
/* Make list of init functions to call. */
|
||||
@ -2276,6 +2317,14 @@ dlopen_object(const char *name, Obj_Entry *refobj, int lo_flags, int mode)
|
||||
|
||||
map_stacks_exec(&lockstate);
|
||||
|
||||
if (initlist_objects_ifunc(&initlist, (mode & RTLD_MODEMASK) == RTLD_NOW,
|
||||
&lockstate) == -1) {
|
||||
objlist_clear(&initlist);
|
||||
dlopen_cleanup(obj);
|
||||
lock_release(rtld_bind_lock, &lockstate);
|
||||
return (NULL);
|
||||
}
|
||||
|
||||
/* Call the init functions. */
|
||||
objlist_call_init(&initlist, &lockstate);
|
||||
objlist_clear(&initlist);
|
||||
|
Loading…
Reference in New Issue
Block a user