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ldd: do not use dlopen(RTLD_TRACE) for dso when format is specified

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Problem is that rtld cannot reliably access updated environment.
This was made more obvious by bfd4c875a1.  The application
environment can be in arbitrary state and place, system components
can observe it only during execve(2), or in case of rtld, right after
execve, when environment is still at know location and format.

Instead spawn ld-elf.so.1 in direct exec mode which can correctly read
all inherited updates to the environment.

PR:	259069
Reviewed by:	arichardson, jhb
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D32464
This commit is contained in:
Konstantin Belousov 2021-10-12 01:35:56 +03:00
parent ca8c576d10
commit 2c7a6dad4d
2 changed files with 12 additions and 1 deletions
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1
usr.bin/ldd/Makefile
View File

@ -3,6 +3,7 @@
PROG?= ldd
SRCS= ldd.c
CFLAGS+= -I${SRCTOP}/libexec/rtld-elf
LIBADD= elf
.include <bsd.prog.mk>

12
usr.bin/ldd/ldd.c
View File

@ -46,6 +46,7 @@ __FBSDID("$FreeBSD$");
#include <fcntl.h>
#include <gelf.h>
#include <libelf.h>
#include <rtld_paths.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
@ -134,6 +135,7 @@ int
main(int argc, char *argv[])
{
char *fmt1, *fmt2;
const char *rtld;
int aflag, c, fd, rval, status, is_shlib, rv, type;
aflag = 0;
@ -234,9 +236,17 @@ main(int argc, char *argv[])
if (is_shlib == 0) {
execl(*argv, *argv, (char *)NULL);
warn("%s", *argv);
} else {
} else if (fmt1 == NULL && fmt2 == NULL) {
dlopen(*argv, RTLD_TRACE);
warnx("%s: %s", *argv, dlerror());
} else {
rtld = _PATH_RTLD;
#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
if (type == TYPE_ELF32)
rtld = _COMPAT32_PATH_RTLD;
#endif
execl(rtld, rtld, "-d", "--",
*argv, (char *)NULL);
}
_exit(1);
}