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rtld: trace preloaded objects

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Before, preloaded objects, if not listed as needed for any normally
linked objects, were silently ignored.

Preloaded objects are printed with the `[preloaded]` herald. The list
includes the objects not listed explicitly as recursive dependencies of
the main object, effectively dsos loaded by LD_PRELOAD mechanism.
vdso is listed as well, since it is not needed by anything.

Since there is no DT_NEEDED entry for LD_PRELOADed objects, they are
usually printed using LD_TRACE_LOADED_OBJECTS_FTM2 format due to the
failure of the heuristic based on the presence of the 'lib' prefix.

Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D34716
This commit is contained in:
Konstantin Belousov 2022-03-31 00:01:54 +03:00
parent db0372808a
commit 0913953c9e
1 changed files with 23 additions and 6 deletions
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29
libexec/rtld-elf/rtld.c
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@ -172,7 +172,7 @@ 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 *tls_get_addr_slow(Elf_Addr **, int, size_t, bool) __noinline;
static void trace_loaded_objects(Obj_Entry *);
static void trace_loaded_objects(Obj_Entry *, bool);
static void unlink_object(Obj_Entry *);
static void unload_object(Obj_Entry *, RtldLockState *lockstate);
static void unref_dag(Obj_Entry *);
@ -872,7 +872,7 @@ _rtld(Elf_Addr *sp, func_ptr_type *exit_proc, Obj_Entry **objp)
dump_auxv(aux_info);
if (ld_tracing) { /* We're done */
trace_loaded_objects(obj_main);
trace_loaded_objects(obj_main, true);
exit(0);
}
@ -3834,7 +3834,7 @@ dlopen_object(const char *name, int fd, Obj_Entry *refobj, int lo_flags,
lock_release(rtld_bind_lock, lockstate);
return (obj);
trace:
trace_loaded_objects(obj);
trace_loaded_objects(obj, false);
if (lockstate == &mlockstate)
lock_release(rtld_bind_lock, lockstate);
exit(0);
@ -4992,17 +4992,17 @@ trace_print_obj(Obj_Entry *obj, const char *name, const char *path,
}
static void
trace_loaded_objects(Obj_Entry *obj)
trace_loaded_objects(Obj_Entry *obj, bool show_preload)
{
const char *fmt1, *fmt2, *main_local;
bool list_containers;
const char *name, *path;
bool first_spurious, list_containers;
trace_calc_fmts(&main_local, &fmt1, &fmt2);
list_containers = ld_get_env_var(LD_TRACE_LOADED_OBJECTS_ALL) != NULL;
for (; obj != NULL; obj = TAILQ_NEXT(obj, next)) {
Needed_Entry *needed;
const char *name, *path;
if (obj->marker)
continue;
@ -5022,6 +5022,23 @@ trace_loaded_objects(Obj_Entry *obj)
fmt1, fmt2);
}
}
if (show_preload) {
first_spurious = true;
TAILQ_FOREACH(obj, &obj_list, next) {
if (obj->marker || obj == obj_main || obj->traced)
continue;
if (first_spurious) {
rtld_printf("[preloaded]\n");
first_spurious = false;
}
Name_Entry *fname = STAILQ_FIRST(&obj->names);
name = fname == NULL ? "<unknown>" : fname->name;
trace_print_obj(obj, name, obj->path, main_local,
fmt1, fmt2);
}
}
}
/*