2c7a6dad4d
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
473 lines
11 KiB
C
473 lines
11 KiB
C
/*-
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* SPDX-License-Identifier: BSD-4-Clause
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*
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* Copyright (c) 1993 Paul Kranenburg
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Paul Kranenburg.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/wait.h>
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#include <machine/elf.h>
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#include <arpa/inet.h>
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#include <dlfcn.h>
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <gelf.h>
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#include <libelf.h>
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#include <rtld_paths.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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/*
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* 32-bit ELF data structures can only be used if the system header[s] declare
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* them. There is no official macro for determining whether they are declared,
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* so check for the existence of one of the 32-macros defined in elf(5).
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*/
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#ifdef ELF32_R_TYPE
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#define ELF32_SUPPORTED
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#endif
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#define LDD_SETENV(name, value, overwrite) do { \
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setenv("LD_" name, value, overwrite); \
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setenv("LD_32_" name, value, overwrite); \
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} while (0)
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#define LDD_UNSETENV(name) do { \
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unsetenv("LD_" name); \
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unsetenv("LD_32_" name); \
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} while (0)
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static int is_executable(const char *fname, int fd, int *is_shlib,
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int *type);
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static void usage(void);
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#define TYPE_UNKNOWN 0
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#define TYPE_ELF 1 /* Architecture default */
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#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
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#define TYPE_ELF32 2 /* Explicit 32 bits on architectures >32 bits */
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#define _PATH_LDD32 "/usr/bin/ldd32"
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static int
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execldd32(char *file, char *fmt1, char *fmt2, int aflag)
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{
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char *argv[9];
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int i, rval, status;
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LDD_UNSETENV("TRACE_LOADED_OBJECTS");
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rval = 0;
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i = 0;
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argv[i++] = strdup(_PATH_LDD32);
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if (aflag)
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argv[i++] = strdup("-a");
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if (fmt1 != NULL) {
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argv[i++] = strdup("-f");
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argv[i++] = strdup(fmt1);
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}
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if (fmt2 != NULL) {
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argv[i++] = strdup("-f");
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argv[i++] = strdup(fmt2);
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}
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argv[i++] = strdup(file);
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argv[i++] = NULL;
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switch (fork()) {
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case -1:
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err(1, "fork");
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break;
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case 0:
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execv(_PATH_LDD32, argv);
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warn("%s", _PATH_LDD32);
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_exit(127);
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break;
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default:
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if (wait(&status) < 0)
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rval = 1;
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else if (WIFSIGNALED(status))
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rval = 1;
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else if (WIFEXITED(status) && WEXITSTATUS(status) != 0)
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rval = 1;
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break;
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}
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while (i--)
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free(argv[i]);
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LDD_SETENV("TRACE_LOADED_OBJECTS", "yes", 1);
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return (rval);
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}
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#endif
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int
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main(int argc, char *argv[])
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{
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char *fmt1, *fmt2;
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const char *rtld;
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int aflag, c, fd, rval, status, is_shlib, rv, type;
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aflag = 0;
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fmt1 = fmt2 = NULL;
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while ((c = getopt(argc, argv, "af:")) != -1) {
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switch (c) {
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case 'a':
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aflag++;
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break;
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case 'f':
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if (fmt1 != NULL) {
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if (fmt2 != NULL)
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errx(1, "too many formats");
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fmt2 = optarg;
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} else
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fmt1 = optarg;
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break;
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default:
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usage();
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/* NOTREACHED */
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}
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}
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argc -= optind;
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argv += optind;
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if (argc <= 0) {
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usage();
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/* NOTREACHED */
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}
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rval = 0;
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for (; argc > 0; argc--, argv++) {
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if ((fd = open(*argv, O_RDONLY, 0)) < 0) {
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warn("%s", *argv);
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rval |= 1;
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continue;
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}
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rv = is_executable(*argv, fd, &is_shlib, &type);
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close(fd);
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if (rv == 0) {
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rval |= 1;
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continue;
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}
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switch (type) {
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case TYPE_ELF:
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break;
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#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
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case TYPE_ELF32:
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rval |= execldd32(*argv, fmt1, fmt2, aflag);
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continue;
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#endif
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case TYPE_UNKNOWN:
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default:
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/*
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* This shouldn't happen unless is_executable()
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* is broken.
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*/
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errx(EDOOFUS, "unknown executable type");
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}
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/* ld.so magic */
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LDD_SETENV("TRACE_LOADED_OBJECTS", "yes", 1);
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if (fmt1 != NULL)
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LDD_SETENV("TRACE_LOADED_OBJECTS_FMT1", fmt1, 1);
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if (fmt2 != NULL)
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LDD_SETENV("TRACE_LOADED_OBJECTS_FMT2", fmt2, 1);
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LDD_SETENV("TRACE_LOADED_OBJECTS_PROGNAME", *argv, 1);
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if (aflag)
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LDD_SETENV("TRACE_LOADED_OBJECTS_ALL", "1", 1);
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else if (fmt1 == NULL && fmt2 == NULL)
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/* Default formats */
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printf("%s:\n", *argv);
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fflush(stdout);
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switch (fork()) {
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case -1:
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err(1, "fork");
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break;
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default:
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if (wait(&status) < 0) {
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warn("wait");
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rval |= 1;
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} else if (WIFSIGNALED(status)) {
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fprintf(stderr, "%s: signal %d\n", *argv,
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WTERMSIG(status));
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rval |= 1;
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} else if (WIFEXITED(status) &&
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WEXITSTATUS(status) != 0) {
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fprintf(stderr, "%s: exit status %d\n", *argv,
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WEXITSTATUS(status));
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rval |= 1;
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}
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break;
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case 0:
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if (is_shlib == 0) {
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execl(*argv, *argv, (char *)NULL);
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warn("%s", *argv);
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} else if (fmt1 == NULL && fmt2 == NULL) {
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dlopen(*argv, RTLD_TRACE);
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warnx("%s: %s", *argv, dlerror());
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} else {
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rtld = _PATH_RTLD;
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#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
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if (type == TYPE_ELF32)
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rtld = _COMPAT32_PATH_RTLD;
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#endif
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execl(rtld, rtld, "-d", "--",
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*argv, (char *)NULL);
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}
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_exit(1);
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}
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}
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return (rval);
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}
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static void
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usage(void)
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{
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fprintf(stderr, "usage: ldd [-a] [-f format] program ...\n");
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exit(1);
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}
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static bool
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has_freebsd_abi_tag(const char *fname, Elf *elf, GElf_Ehdr *ehdr, off_t offset,
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size_t len)
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{
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Elf_Data dst, src;
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const Elf_Note *note;
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char *buf;
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const char *name;
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void *copy;
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size_t namesz, descsz;
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bool has_abi_tag;
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buf = elf_rawfile(elf, NULL);
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if (buf == NULL) {
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warnx("%s: %s", fname, elf_errmsg(0));
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return (false);
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}
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memset(&src, 0, sizeof(src));
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src.d_buf = buf + offset;
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src.d_size = len;
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src.d_type = ELF_T_NOTE;
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src.d_version = EV_CURRENT;
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memset(&dst, 0, sizeof(dst));
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dst.d_buf = copy = malloc(len);
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dst.d_size = len;
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dst.d_type = ELF_T_NOTE;
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dst.d_version = EV_CURRENT;
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if (gelf_xlatetom(elf, &dst, &src, ehdr->e_ident[EI_DATA]) == NULL) {
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warnx("%s: failed to parse notes: %s", fname, elf_errmsg(0));
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free(copy);
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return (false);
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}
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buf = copy;
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has_abi_tag = false;
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for (;;) {
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if (len < sizeof(*note))
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break;
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note = (const void *)buf;
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buf += sizeof(*note);
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len -= sizeof(*note);
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namesz = roundup2(note->n_namesz, sizeof(uint32_t));
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descsz = roundup2(note->n_descsz, sizeof(uint32_t));
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if (len < namesz + descsz)
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break;
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name = buf;
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if (note->n_namesz == sizeof(ELF_NOTE_FREEBSD) &&
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strncmp(name, ELF_NOTE_FREEBSD, note->n_namesz) == 0 &&
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note->n_type == NT_FREEBSD_ABI_TAG &&
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note->n_descsz == sizeof(uint32_t)) {
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has_abi_tag = true;
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break;
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}
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buf += namesz + descsz;
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len -= namesz + descsz;
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}
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free(copy);
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return (has_abi_tag);
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}
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static bool
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is_pie(const char *fname, Elf *elf, GElf_Ehdr *ehdr, off_t offset, size_t len)
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{
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Elf_Data dst, src;
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char *buf;
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void *copy;
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const GElf_Dyn *dyn;
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size_t dynsize;
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u_int count, i;
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bool pie;
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buf = elf_rawfile(elf, NULL);
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if (buf == NULL) {
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warnx("%s: %s", fname, elf_errmsg(0));
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return (false);
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}
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dynsize = gelf_fsize(elf, ELF_T_DYN, 1, EV_CURRENT);
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if (dynsize == 0) {
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warnx("%s: %s", fname, elf_errmsg(0));
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return (false);
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}
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count = len / dynsize;
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memset(&src, 0, sizeof(src));
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src.d_buf = buf + offset;
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src.d_size = len;
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src.d_type = ELF_T_DYN;
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src.d_version = EV_CURRENT;
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memset(&dst, 0, sizeof(dst));
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dst.d_buf = copy = malloc(count * sizeof(*dyn));
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dst.d_size = count * sizeof(*dyn);
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dst.d_type = ELF_T_DYN;
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dst.d_version = EV_CURRENT;
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if (gelf_xlatetom(elf, &dst, &src, ehdr->e_ident[EI_DATA]) == NULL) {
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warnx("%s: failed to parse .dynamic: %s", fname, elf_errmsg(0));
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free(copy);
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return (false);
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}
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dyn = copy;
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pie = false;
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for (i = 0; i < count; i++) {
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if (dyn[i].d_tag != DT_FLAGS_1)
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continue;
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pie = (dyn[i].d_un.d_val & DF_1_PIE) != 0;
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break;
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}
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free(copy);
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return (pie);
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}
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static int
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is_executable(const char *fname, int fd, int *is_shlib, int *type)
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{
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Elf *elf;
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GElf_Ehdr ehdr;
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GElf_Phdr phdr;
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bool dynamic, freebsd, pie;
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int i;
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*is_shlib = 0;
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*type = TYPE_UNKNOWN;
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dynamic = false;
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freebsd = false;
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pie = false;
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if (elf_version(EV_CURRENT) == EV_NONE) {
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warnx("unsupported libelf");
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return (0);
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}
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elf = elf_begin(fd, ELF_C_READ, NULL);
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if (elf == NULL) {
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warnx("%s: %s", fname, elf_errmsg(0));
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return (0);
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}
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if (elf_kind(elf) != ELF_K_ELF) {
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elf_end(elf);
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warnx("%s: not a dynamic ELF executable", fname);
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return (0);
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}
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if (gelf_getehdr(elf, &ehdr) == NULL) {
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warnx("%s: %s", fname, elf_errmsg(0));
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elf_end(elf);
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return (0);
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}
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*type = TYPE_ELF;
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#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
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if (gelf_getclass(elf) == ELFCLASS32) {
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*type = TYPE_ELF32;
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}
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#endif
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freebsd = ehdr.e_ident[EI_OSABI] == ELFOSABI_FREEBSD;
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for (i = 0; i < ehdr.e_phnum; i++) {
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if (gelf_getphdr(elf, i, &phdr) == NULL) {
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warnx("%s: %s", fname, elf_errmsg(0));
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elf_end(elf);
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return (0);
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}
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switch (phdr.p_type) {
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case PT_NOTE:
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if (ehdr.e_ident[EI_OSABI] == ELFOSABI_NONE && !freebsd)
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freebsd = has_freebsd_abi_tag(fname, elf, &ehdr,
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phdr.p_offset, phdr.p_filesz);
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break;
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case PT_DYNAMIC:
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dynamic = true;
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if (ehdr.e_type == ET_DYN)
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pie = is_pie(fname, elf, &ehdr, phdr.p_offset,
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phdr.p_filesz);
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break;
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}
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}
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if (!dynamic) {
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elf_end(elf);
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warnx("%s: not a dynamic ELF executable", fname);
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return (0);
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}
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if (ehdr.e_type == ET_DYN && !pie) {
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*is_shlib = 1;
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if (!freebsd) {
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elf_end(elf);
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warnx("%s: not a FreeBSD ELF shared object", fname);
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return (0);
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}
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}
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elf_end(elf);
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return (1);
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}
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