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      1 /* $NetBSD: nlist_elf32.c,v 1.19 2010/08/28 21:30:03 joerg 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 1.19 2010/08/28 21:30:03 joerg 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 
     76 typedef 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 
     90 static const char *kfile;
     91 
     92 int
     93 ELFNAMEEND(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 
    375 unmap:
    376 	if (malloced)
    377 		free(mappedfile);
    378 	else
    379 		munmap(mappedfile, mappedsize);
    380 out:
    381 	return (rv);
    382 }
    383 
    384 #endif
    385