1/* $NetBSD: nlist_elf32.c,v 1.18 2003/11/12 13:31:07 grant Exp $ */
2
3/*
4 * Copyright (c) 1996 Christopher G. Demetriou
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 for the
18 *          NetBSD Project.  See http://www.NetBSD.org/ for
19 *          information about NetBSD.
20 * 4. The name of the author may not be used to endorse or promote products
21 *    derived from this software without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 *
34 * <<Id: LICENSE,v 1.2 2000/06/14 15:57:33 cgd Exp>>
35 */
36
37#include <sys/cdefs.h>
38#ifndef lint
39__RCSID("$NetBSD: nlist_elf32.c,v 1.18 2003/11/12 13:31:07 grant Exp $");
40#endif /* not lint */
41
42/* If not included by nlist_elf64.c, ELFSIZE won't be defined. */
43#ifndef ELFSIZE
44#define	ELFSIZE		32
45#endif
46
47#include <sys/param.h>
48#include <sys/mman.h>
49#include <sys/stat.h>
50#include <sys/sysctl.h>
51#include <sys/ioctl.h>
52#include <sys/ksyms.h>
53
54#include <a.out.h>
55#include <db.h>
56#include <err.h>
57#include <errno.h>
58#include <fcntl.h>
59#include <kvm.h>
60#include <limits.h>
61#include <paths.h>
62#include <stdio.h>
63#include <stdlib.h>
64#include <string.h>
65#include <unistd.h>
66
67#include "extern.h"
68
69#if defined(NLIST_ELF32) || defined(NLIST_ELF64)
70#include <sys/exec_elf.h>
71#endif
72
73#if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \
74    (defined(NLIST_ELF64) && (ELFSIZE == 64))
75
76typedef struct nlist NLIST;
77#define	_strx	n_un.n_strx
78#define	_name	n_un.n_name
79
80#define	badfmt(str)							\
81	do {								\
82		warnx("%s: %s: %s", kfile, str, strerror(EFTYPE));	\
83		punt();							\
84	} while (0)
85
86#define	check(off, size)	((off < 0) || (off + size > mappedsize))
87#define	BAD			do { rv = -1; goto out; } while (0)
88#define	BADUNMAP		do { rv = -1; goto unmap; } while (0)
89
90static const char *kfile;
91
92int
93ELFNAMEEND(create_knlist)(name, db)
94	const char *name;
95	DB *db;
96{
97	struct stat st;
98	struct nlist nbuf;
99	DBT key, data;
100	char *mappedfile, *symname, *nsymname, *fsymname, *tmpcp, *strtab;
101	size_t mappedsize, symnamesize, fsymnamesize;
102	Elf_Ehdr *ehdrp;
103	Elf_Shdr *shdrp, *symshdrp, *symstrshdrp;
104	Elf_Sym *symp;
105	Elf_Off shdr_off;
106	Elf_Word shdr_size;
107#if (ELFSIZE == 32)
108	Elf32_Half nshdr;
109#elif (ELFSIZE == 64)
110	Elf64_Word nshdr;
111#endif
112	unsigned long i, nsyms;
113	int fd, rv, malloced = 0, isksyms;
114
115	rv = -1;
116#ifdef __GNUC__
117	/* fix compiler warnings */
118	symshdrp = NULL;
119	symstrshdrp = NULL;
120#endif
121
122	/*
123	 * Open and map the whole file.  If we can't open/stat it,
124	 * something bad is going on so we punt.
125	 */
126	kfile = name;
127	if ((fd = open(name, O_RDONLY, 0)) < 0) {
128		warn("%s", kfile);
129		punt();
130	}
131	if (fstat(fd, &st) < 0) {
132		warn("%s", kfile);
133		punt();
134	}
135	if (st.st_size > SIZE_T_MAX)
136		BAD;
137
138
139	/*
140	 * Map the file in its entirety.
141	 */
142	mappedfile = MAP_FAILED;
143	mappedsize = st.st_size;
144	isksyms = S_ISCHR(st.st_mode) &&
145	    strncmp(name, _PATH_KSYMS, sizeof(_PATH_KSYMS)) == 0;
146
147	if (mappedsize == 0) {
148		/* if it's a character device, stat returns size 0 */
149		if (!isksyms)
150			BAD;
151	} else {
152		mappedfile = mmap(NULL, mappedsize, PROT_READ,
153		    MAP_PRIVATE|MAP_FILE, fd, 0);
154	}
155
156	/*
157	 * If mmap failed, try to read the file instead.
158	 */
159	if (mappedfile == MAP_FAILED) {
160		int allocsiz, readsz;
161
162		if (isksyms != 0) {
163			if (ioctl(fd, KIOCGSIZE, &allocsiz) < 0)
164				BAD;
165			mappedsize = allocsiz;
166		} else
167			allocsiz = mappedsize;
168
169		if ((mappedfile = malloc(mappedsize)) == NULL)
170			BAD;
171		malloced = 1;
172		if ((readsz = read(fd, mappedfile, mappedsize)) < 0)
173			BADUNMAP;
174
175		if (readsz != mappedsize) /* Sanity */
176			BADUNMAP;
177	}
178	/*
179	 * Make sure we can access the executable's header
180	 * directly, and make sure the recognize the executable
181	 * as an ELF binary.
182	 */
183	if (check(0, sizeof *ehdrp))
184		BADUNMAP;
185	ehdrp = (Elf_Ehdr *)&mappedfile[0];
186
187	if (memcmp(ehdrp->e_ident, ELFMAG, SELFMAG) != 0 ||
188	    ehdrp->e_ident[EI_CLASS] != ELFCLASS)
189		BADUNMAP;
190
191	switch (ehdrp->e_machine) {
192	ELFDEFNNAME(MACHDEP_ID_CASES)
193
194	default:
195		BADUNMAP;
196	}
197
198	/*
199	 * We've recognized it as an ELF binary.  From here
200	 * on out, all errors are fatal.
201	 */
202
203	/*
204	 * Find the symbol list and string table.
205	 */
206	nshdr = ehdrp->e_shnum;
207	shdr_off = ehdrp->e_shoff;
208	shdr_size = ehdrp->e_shentsize * nshdr;
209
210	if (check(shdr_off, shdr_size) ||
211	    (sizeof *shdrp != ehdrp->e_shentsize))
212		badfmt("bogus section header table");
213	shdrp = (Elf_Shdr *)&mappedfile[shdr_off];
214
215	for (i = 0; i < nshdr; i++) {
216		if (shdrp[i].sh_type == SHT_SYMTAB) {
217			symshdrp = &shdrp[i];
218			symstrshdrp = &shdrp[shdrp[i].sh_link];
219		}
220	}
221
222	if (symshdrp == NULL)
223		badfmt("no symbol section header found");
224	if (symshdrp->sh_offset == 0)
225		badfmt("stripped");
226	if (check(symshdrp->sh_offset, symshdrp->sh_size))
227		badfmt("bogus symbol section header");
228	if (check(symstrshdrp->sh_offset, symstrshdrp->sh_size))
229		badfmt("bogus symbol string section header");
230
231	symp = (Elf_Sym *)&mappedfile[symshdrp->sh_offset];
232	nsyms = symshdrp->sh_size / sizeof(*symp);
233	strtab = &mappedfile[symstrshdrp->sh_offset];
234
235	/*
236	 * Set up the data item, pointing to a nlist structure.
237	 * which we fill in for each symbol.
238	 */
239	data.data = (u_char *)&nbuf;
240	data.size = sizeof(nbuf);
241
242	/*
243	 * Create a buffer (to be expanded later, if necessary)
244	 * to hold symbol names after we've added underscores
245	 * to them.
246	 */
247	symnamesize = 1024;
248	if ((symname = malloc(symnamesize)) == NULL) {
249		warn("malloc");
250		punt();
251	}
252
253	/*
254	 * Read each symbol and enter it into the database.
255	 */
256	for (i = 0; i < nsyms; i++) {
257
258		/*
259		 * No symbol name; ignore this symbol.
260		 */
261		if (symp[i].st_name == 0)
262			continue;
263
264		/*
265		 * Find symbol name, copy it (with added underscore) to
266		 * temporary buffer, and prepare the database key for
267		 * insertion.
268		 */
269		fsymname = &strtab[symp[i].st_name];
270		fsymnamesize = strlen(fsymname) + 1;
271		while (symnamesize < fsymnamesize + 1) {
272			if ((nsymname = realloc(symname, symnamesize * 2)) == NULL) {
273				warn("malloc");
274				punt();
275			}
276			symname = nsymname;
277			symnamesize *= 2;
278		}
279		strlcpy(symname, "_", symnamesize);
280		strlcat(symname, fsymname, symnamesize);
281
282		key.data = symname;
283		key.size = strlen((char *)key.data);
284
285		/*
286		 * Convert the symbol information into an nlist structure,
287		 * as best we can.
288		 */
289		nbuf.n_value = symp[i].st_value;
290		switch (ELFDEFNNAME(ST_TYPE)(symp[i].st_info)) {
291		default:
292		case STT_NOTYPE:
293			nbuf.n_type = N_UNDF;
294			break;
295		case STT_OBJECT:
296			nbuf.n_type = N_DATA;
297			break;
298		case STT_FUNC:
299			nbuf.n_type = N_TEXT;
300			break;
301		case STT_FILE:
302			nbuf.n_type = N_FN;
303			break;
304		}
305		if (ELFDEFNNAME(ST_BIND)(symp[i].st_info) != STB_LOCAL)
306			nbuf.n_type |= N_EXT;
307		nbuf.n_desc = 0;				/* XXX */
308		nbuf.n_other = 0;				/* XXX */
309
310		/*
311		 * Enter the symbol into the database.
312		 */
313		if (db->put(db, &key, &data, 0)) {
314			warn("record enter");
315			punt();
316		}
317
318		/*
319		 * If it's the kernel version string, we've gotta keep
320		 * some extra data around.  Under a separate key,
321		 * we enter the first line (i.e. up to the first newline,
322		 * with the newline replaced by a NUL to terminate the
323		 * entered string) of the version string.
324		 */
325		if (strcmp((char *)key.data, VRS_SYM) == 0) {
326			key.data = (u_char *)VRS_KEY;
327			key.size = sizeof(VRS_KEY) - 1;
328			/* Find the version string, relative to its section */
329			if (isksyms) {
330				/* reading from /dev/ksyms, use sysctl */
331				size_t sz;
332				int mib[2];
333				char *kv;
334
335				mib[0] = CTL_KERN;
336				mib[1] = KERN_VERSION;
337				if (sysctl(mib, 2, NULL, &sz, NULL, 0) == -1) {
338					warn("sysctl version size");
339					punt();
340				}
341				if ((kv = malloc(sz)) == NULL) {
342					warn("malloc version string");
343					punt();
344				}
345				if (sysctl(mib, 2, kv, &sz, NULL, 0) == -1) {
346					warn("sysctl version string");
347					punt();
348				}
349				data.data = kv;
350			} else
351				data.data = strdup(&mappedfile[nbuf.n_value -
352				    shdrp[symp[i].st_shndx].sh_addr +
353				    shdrp[symp[i].st_shndx].sh_offset]);
354			/* assumes newline terminates version. */
355			if ((tmpcp = strchr(data.data, '\n')) != NULL)
356				*tmpcp = '\0';
357			data.size = strlen((char *)data.data);
358
359			if (db->put(db, &key, &data, 0)) {
360				warn("record enter");
361				punt();
362			}
363
364			/* free pointer created by strdup(). */
365			free(data.data);
366
367			/* Restore to original values */
368			data.data = (u_char *)&nbuf;
369			data.size = sizeof(nbuf);
370		}
371	}
372
373	rv = 0;
374
375unmap:
376	if (malloced)
377		free(mappedfile);
378	else
379		munmap(mappedfile, mappedsize);
380out:
381	return (rv);
382}
383
384#endif
385