1/*-
2 * SPDX-License-Identifier: BSD-4-Clause
3 *
4 * Copyright (c) 1993 Paul Kranenburg
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 *    must display the following acknowledgement:
17 *      This product includes software developed by Paul Kranenburg.
18 * 4. The name of the author may not be used to endorse or promote products
19 *    derived from this software without specific prior written permission
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33#include <sys/param.h>
34#include <sys/wait.h>
35
36#include <machine/elf.h>
37
38#include <arpa/inet.h>
39
40#include <dlfcn.h>
41#include <err.h>
42#include <errno.h>
43#include <fcntl.h>
44#include <gelf.h>
45#include <libelf.h>
46#include <rtld_paths.h>
47#include <stdbool.h>
48#include <stdio.h>
49#include <stdlib.h>
50#include <string.h>
51#include <unistd.h>
52
53/*
54 * 32-bit ELF data structures can only be used if the system header[s] declare
55 * them.  There is no official macro for determining whether they are declared,
56 * so check for the existence of one of the 32-macros defined in elf(5).
57 */
58#ifdef ELF32_R_TYPE
59#define	ELF32_SUPPORTED
60#endif
61
62#define	LDD_SETENV(name, value, overwrite) do {		\
63	setenv("LD_" name, value, overwrite);		\
64	setenv("LD_32_" name, value, overwrite);	\
65} while (0)
66
67#define	LDD_UNSETENV(name) do {		\
68	unsetenv("LD_" name);		\
69	unsetenv("LD_32_" name);	\
70} while (0)
71
72static int	is_executable(const char *fname, int fd, int *is_shlib,
73		    int *type);
74static void	usage(void);
75
76#define	TYPE_UNKNOWN	0
77#define	TYPE_ELF	1	/* Architecture default */
78#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
79#define	TYPE_ELF32	2	/* Explicit 32 bits on architectures >32 bits */
80
81#define	_PATH_LDD32	"/usr/bin/ldd32"
82
83static int
84execldd32(char *file, char *fmt1, char *fmt2, int aflag)
85{
86	char *argv[9];
87	int i, rval, status;
88
89	LDD_UNSETENV("TRACE_LOADED_OBJECTS");
90	rval = 0;
91	i = 0;
92	argv[i++] = strdup(_PATH_LDD32);
93	if (aflag)
94		argv[i++] = strdup("-a");
95	if (fmt1 != NULL) {
96		argv[i++] = strdup("-f");
97		argv[i++] = strdup(fmt1);
98	}
99	if (fmt2 != NULL) {
100		argv[i++] = strdup("-f");
101		argv[i++] = strdup(fmt2);
102	}
103	argv[i++] = strdup(file);
104	argv[i++] = NULL;
105
106	switch (fork()) {
107	case -1:
108		err(1, "fork");
109		break;
110	case 0:
111		execv(_PATH_LDD32, argv);
112		warn("%s", _PATH_LDD32);
113		_exit(127);
114		break;
115	default:
116		if (wait(&status) < 0)
117			rval = 1;
118		else if (WIFSIGNALED(status))
119			rval = 1;
120		else if (WIFEXITED(status) && WEXITSTATUS(status) != 0)
121			rval = 1;
122		break;
123	}
124	while (i--)
125		free(argv[i]);
126	LDD_SETENV("TRACE_LOADED_OBJECTS", "yes", 1);
127	return (rval);
128}
129#endif
130
131int
132main(int argc, char *argv[])
133{
134	char *fmt1, *fmt2;
135	const char *rtld;
136	int aflag, c, fd, rval, status, is_shlib, rv, type;
137
138	aflag = 0;
139	fmt1 = fmt2 = NULL;
140
141	while ((c = getopt(argc, argv, "af:")) != -1) {
142		switch (c) {
143		case 'a':
144			aflag++;
145			break;
146		case 'f':
147			if (fmt1 != NULL) {
148				if (fmt2 != NULL)
149					errx(1, "too many formats");
150				fmt2 = optarg;
151			} else
152				fmt1 = optarg;
153			break;
154		default:
155			usage();
156			/* NOTREACHED */
157		}
158	}
159	argc -= optind;
160	argv += optind;
161
162	if (argc <= 0) {
163		usage();
164		/* NOTREACHED */
165	}
166
167	rval = 0;
168	for (; argc > 0; argc--, argv++) {
169		if ((fd = open(*argv, O_RDONLY | O_VERIFY, 0)) < 0) {
170			warn("%s", *argv);
171			rval |= 1;
172			continue;
173		}
174		rv = is_executable(*argv, fd, &is_shlib, &type);
175		close(fd);
176		if (rv == 0) {
177			rval |= 1;
178			continue;
179		}
180
181		switch (type) {
182		case TYPE_ELF:
183			break;
184#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
185		case TYPE_ELF32:
186			rval |= execldd32(*argv, fmt1, fmt2, aflag);
187			continue;
188#endif
189		case TYPE_UNKNOWN:
190		default:
191			/*
192			 * This shouldn't happen unless is_executable()
193			 * is broken.
194			 */
195			errx(EDOOFUS, "unknown executable type");
196		}
197
198		/* ld.so magic */
199		LDD_SETENV("TRACE_LOADED_OBJECTS", "yes", 1);
200		if (fmt1 != NULL)
201			LDD_SETENV("TRACE_LOADED_OBJECTS_FMT1", fmt1, 1);
202		if (fmt2 != NULL)
203			LDD_SETENV("TRACE_LOADED_OBJECTS_FMT2", fmt2, 1);
204
205		LDD_SETENV("TRACE_LOADED_OBJECTS_PROGNAME", *argv, 1);
206		if (aflag)
207			LDD_SETENV("TRACE_LOADED_OBJECTS_ALL", "1", 1);
208		else if (fmt1 == NULL && fmt2 == NULL)
209			/* Default formats */
210			printf("%s:\n", *argv);
211		fflush(stdout);
212
213		switch (fork()) {
214		case -1:
215			err(1, "fork");
216			break;
217		default:
218			if (wait(&status) < 0) {
219				warn("wait");
220				rval |= 1;
221			} else if (WIFSIGNALED(status)) {
222				fprintf(stderr, "%s: signal %d\n", *argv,
223				    WTERMSIG(status));
224				rval |= 1;
225			} else if (WIFEXITED(status) &&
226			    WEXITSTATUS(status) != 0) {
227				fprintf(stderr, "%s: exit status %d\n", *argv,
228				    WEXITSTATUS(status));
229				rval |= 1;
230			}
231			break;
232		case 0:
233			rtld = _PATH_RTLD;
234#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
235			if (type == TYPE_ELF32)
236				rtld = __PATH_RTLD("32");
237#endif
238			if (is_shlib == 0) {
239				execl(rtld, rtld, "--",
240				    *argv, (char *)NULL);
241				warn("%s", *argv);
242			} else if (fmt1 == NULL && fmt2 == NULL && !aflag) {
243				dlopen(*argv, RTLD_TRACE);
244				warnx("%s: %s", *argv, dlerror());
245			} else {
246				execl(rtld, rtld, "-d", "--",
247				    *argv, (char *)NULL);
248			}
249			_exit(1);
250		}
251	}
252
253	return (rval);
254}
255
256static void
257usage(void)
258{
259
260	fprintf(stderr,
261	    "usage: ldd [-a] [-f format [-f format]] program ...\n");
262	exit(1);
263}
264
265static bool
266has_freebsd_abi_tag(const char *fname, Elf *elf, GElf_Ehdr *ehdr, off_t offset,
267    size_t len)
268{
269	Elf_Data dst, src;
270	const Elf_Note *note;
271	char *buf;
272	const char *name;
273	void *copy;
274	size_t namesz, descsz;
275	bool has_abi_tag;
276
277	buf = elf_rawfile(elf, NULL);
278	if (buf == NULL) {
279		warnx("%s: %s", fname, elf_errmsg(0));
280		return (false);
281	}
282
283	memset(&src, 0, sizeof(src));
284	src.d_buf = buf + offset;
285	src.d_size = len;
286	src.d_type = ELF_T_NOTE;
287	src.d_version = EV_CURRENT;
288
289	memset(&dst, 0, sizeof(dst));
290	dst.d_buf = copy = malloc(len);
291	dst.d_size = len;
292	dst.d_type = ELF_T_NOTE;
293	dst.d_version = EV_CURRENT;
294
295	if (gelf_xlatetom(elf, &dst, &src, ehdr->e_ident[EI_DATA]) == NULL) {
296		warnx("%s: failed to parse notes: %s", fname, elf_errmsg(0));
297		free(copy);
298		return (false);
299	}
300
301	buf = copy;
302	has_abi_tag = false;
303	for (;;) {
304		if (len < sizeof(*note))
305			break;
306
307		note = (const void *)buf;
308		buf += sizeof(*note);
309		len -= sizeof(*note);
310
311		namesz = roundup2(note->n_namesz, sizeof(uint32_t));
312		descsz = roundup2(note->n_descsz, sizeof(uint32_t));
313		if (len < namesz + descsz)
314			break;
315
316		name = buf;
317		if (note->n_namesz == sizeof(ELF_NOTE_FREEBSD) &&
318		    strncmp(name, ELF_NOTE_FREEBSD, note->n_namesz) == 0 &&
319		    note->n_type == NT_FREEBSD_ABI_TAG &&
320		    note->n_descsz == sizeof(uint32_t)) {
321			has_abi_tag = true;
322			break;
323		}
324
325		buf += namesz + descsz;
326		len -= namesz + descsz;
327	}
328
329	free(copy);
330	return (has_abi_tag);
331}
332
333static bool
334is_pie(const char *fname, Elf *elf, GElf_Ehdr *ehdr, off_t offset, size_t len)
335{
336	Elf_Data dst, src;
337	char *buf;
338	void *copy;
339	const GElf_Dyn *dyn;
340	size_t dynsize;
341	u_int count, i;
342	bool pie;
343
344	buf = elf_rawfile(elf, NULL);
345	if (buf == NULL) {
346		warnx("%s: %s", fname, elf_errmsg(0));
347		return (false);
348	}
349
350	dynsize = gelf_fsize(elf, ELF_T_DYN, 1, EV_CURRENT);
351	if (dynsize == 0) {
352		warnx("%s: %s", fname, elf_errmsg(0));
353		return (false);
354	}
355	count = len / dynsize;
356
357	memset(&src, 0, sizeof(src));
358	src.d_buf = buf + offset;
359	src.d_size = len;
360	src.d_type = ELF_T_DYN;
361	src.d_version = EV_CURRENT;
362
363	memset(&dst, 0, sizeof(dst));
364	dst.d_buf = copy = malloc(count * sizeof(*dyn));
365	dst.d_size = count * sizeof(*dyn);
366	dst.d_type = ELF_T_DYN;
367	dst.d_version = EV_CURRENT;
368
369	if (gelf_xlatetom(elf, &dst, &src, ehdr->e_ident[EI_DATA]) == NULL) {
370		warnx("%s: failed to parse .dynamic: %s", fname, elf_errmsg(0));
371		free(copy);
372		return (false);
373	}
374
375	dyn = copy;
376	pie = false;
377	for (i = 0; i < count; i++) {
378		if (dyn[i].d_tag != DT_FLAGS_1)
379			continue;
380
381		pie = (dyn[i].d_un.d_val & DF_1_PIE) != 0;
382		break;
383	}
384
385	free(copy);
386	return (pie);
387}
388
389static int
390is_executable(const char *fname, int fd, int *is_shlib, int *type)
391{
392	Elf *elf;
393	GElf_Ehdr ehdr;
394	GElf_Phdr phdr;
395	bool dynamic, freebsd, pie;
396	int i;
397
398	*is_shlib = 0;
399	*type = TYPE_UNKNOWN;
400	dynamic = false;
401	freebsd = false;
402	pie = false;
403
404	if (elf_version(EV_CURRENT) == EV_NONE) {
405		warnx("unsupported libelf");
406		return (0);
407	}
408	elf = elf_begin(fd, ELF_C_READ, NULL);
409	if (elf == NULL) {
410		warnx("%s: %s", fname, elf_errmsg(0));
411		return (0);
412	}
413	if (elf_kind(elf) != ELF_K_ELF) {
414		elf_end(elf);
415		warnx("%s: not a dynamic ELF executable", fname);
416		return (0);
417	}
418	if (gelf_getehdr(elf, &ehdr) == NULL) {
419		warnx("%s: %s", fname, elf_errmsg(0));
420		elf_end(elf);
421		return (0);
422	}
423
424	*type = TYPE_ELF;
425#if __ELF_WORD_SIZE > 32 && defined(ELF32_SUPPORTED)
426	if (gelf_getclass(elf) == ELFCLASS32) {
427		*type = TYPE_ELF32;
428	}
429#endif
430
431	freebsd = ehdr.e_ident[EI_OSABI] == ELFOSABI_FREEBSD;
432	for (i = 0; i < ehdr.e_phnum; i++) {
433		if (gelf_getphdr(elf, i, &phdr) == NULL) {
434			warnx("%s: %s", fname, elf_errmsg(0));
435			elf_end(elf);
436			return (0);
437		}
438		switch (phdr.p_type) {
439		case PT_NOTE:
440			if (ehdr.e_ident[EI_OSABI] == ELFOSABI_NONE && !freebsd)
441				freebsd = has_freebsd_abi_tag(fname, elf, &ehdr,
442				    phdr.p_offset, phdr.p_filesz);
443			break;
444		case PT_DYNAMIC:
445			dynamic = true;
446			if (ehdr.e_type == ET_DYN)
447				pie = is_pie(fname, elf, &ehdr, phdr.p_offset,
448				    phdr.p_filesz);
449			break;
450		}
451	}
452
453	if (!dynamic) {
454		elf_end(elf);
455		warnx("%s: not a dynamic ELF executable", fname);
456		return (0);
457	}
458
459	if (ehdr.e_type == ET_DYN && !pie) {
460		*is_shlib = 1;
461
462		if (!freebsd) {
463			elf_end(elf);
464			warnx("%s: not a FreeBSD ELF shared object", fname);
465			return (0);
466		}
467	}
468
469	elf_end(elf);
470	return (1);
471}
472