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nlist_elf32.c revision 1.35 
      1 /* $NetBSD: nlist_elf32.c,v 1.35 2012/03/21 02:18:14 christos 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 #if defined(LIBC_SCCS) && !defined(lint)
     39 __RCSID("$NetBSD: nlist_elf32.c,v 1.35 2012/03/21 02:18:14 christos Exp $");
     40 #endif /* LIBC_SCCS and 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 "namespace.h"
     48 #include <sys/param.h>
     49 #include <sys/mman.h>
     50 #include <sys/stat.h>
     51 #include <sys/file.h>
     52 #include <sys/ioctl.h>
     53 #include <sys/ksyms.h>
     54 
     55 #include <assert.h>
     56 #include <errno.h>
     57 #include <stdio.h>
     58 #include <string.h>
     59 #include <unistd.h>
     60 #include <nlist.h>
     61 
     62 #include "nlist_private.h"
     63 #if defined(NLIST_ELF32) || defined(NLIST_ELF64)
     64 #include <sys/exec_elf.h>
     65 #endif
     66 
     67 #if (defined(NLIST_ELF32) && (ELFSIZE == 32)) || \
     68     (defined(NLIST_ELF64) && (ELFSIZE == 64))
     69 
     70 /* No need to check for off < 0 because it is unsigned */
     71 #define	check(off, size)	(off + size > mappedsize)
     72 #define	BAD			goto out
     73 #define	BADUNMAP		goto unmap
     74 
     75 int
     76 ELFNAMEEND(__fdnlist)(int fd, struct nlist *list)
     77 {
     78 	struct stat st;
     79 	Elf_Ehdr ehdr;
     80 #if _LP64 || ELFSIZE == 32
     81 #if (ELFSIZE == 32)
     82 	Elf32_Half nshdr;
     83 #elif (ELFSIZE == 64)
     84 	Elf64_Word nshdr;
     85 #endif
     86 	/* Only support 64+32 mode on LP64; no support for 64 mode on ILP32 */
     87 	Elf_Ehdr *ehdrp;
     88 	Elf_Shdr *shdrp, *symshdrp, *symstrshdrp;
     89 	Elf_Sym *symp;
     90 	Elf_Off shdr_off;
     91 	Elf_Word shdr_size;
     92 	struct nlist *p;
     93 	char *mappedfile, *strtab;
     94 	size_t mappedsize, nsyms;
     95 	int nent;
     96 #endif
     97 	int rv;
     98 	size_t i;
     99 
    100 	_DIAGASSERT(fd != -1);
    101 	_DIAGASSERT(list != NULL);
    102 
    103 	rv = -1;
    104 
    105 	/*
    106 	 * If we can't fstat() the file, something bad is going on.
    107 	 */
    108 	if (fstat(fd, &st) < 0)
    109 		BAD;
    110 
    111 	/*
    112 	 * Map the file in its entirety.
    113 	 */
    114 	if ((uintmax_t)st.st_size > (uintmax_t)SIZE_T_MAX) {
    115 		errno = EFBIG;
    116 		BAD;
    117 	}
    118 
    119 	/*
    120 	 * Read the elf header of the file.
    121 	 */
    122 	if ((ssize_t)(i = pread(fd, &ehdr, sizeof(Elf_Ehdr), (off_t)0)) == -1)
    123 		BAD;
    124 
    125 	/*
    126 	 * Check that the elf header is correct.
    127 	 */
    128 	if (i != sizeof(Elf_Ehdr))
    129 		BAD;
    130 	if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
    131 	    ehdr.e_ident[EI_CLASS] != ELFCLASS)
    132 		BAD;
    133 
    134 	switch (ehdr.e_machine) {
    135 	ELFDEFNNAME(MACHDEP_ID_CASES)
    136 
    137 	default:
    138 		BAD;
    139 	}
    140 #if _LP64 || ELFSIZE == 32
    141 	symshdrp = symstrshdrp = NULL;
    142 
    143 	/* Only support 64+32 mode on LP64; no support for 64 mode on ILP32 */
    144 	if (S_ISCHR(st.st_mode)) {
    145 		const char *nlistname;
    146 		struct ksyms_gsymbol kg;
    147 		Elf_Sym sym;
    148 
    149 		/*
    150 		 * Character device; assume /dev/ksyms.
    151 		 */
    152 		nent = 0;
    153 		for (p = list; !ISLAST(p); ++p) {
    154 
    155 			p->n_other = 0;
    156 			p->n_desc = 0;
    157 			nlistname = N_NAME(p);
    158 			if (*nlistname == '_')
    159 				nlistname++;
    160 
    161 			kg.kg_name = nlistname;
    162 			kg.kg_sym = &sym;
    163 			if (ioctl(fd, KIOCGSYMBOL, &kg) == 0) {
    164 				p->n_value = (uintptr_t)sym.st_value;
    165 				switch (ELF_ST_TYPE(sym.st_info)) {
    166 				case STT_NOTYPE:
    167 					p->n_type = N_UNDF;
    168 					break;
    169 				case STT_COMMON:
    170 				case STT_OBJECT:
    171 					p->n_type = N_DATA;
    172 					break;
    173 				case STT_FUNC:
    174 					p->n_type = N_TEXT;
    175 					break;
    176 				case STT_FILE:
    177 					p->n_type = N_FN;
    178 					break;
    179 				default:
    180 					p->n_type = 0;
    181 					/* catch other enumerations for gcc */
    182 					break;
    183 				}
    184 				if (ELF_ST_BIND(sym.st_info) != STB_LOCAL)
    185 					p->n_type |= N_EXT;
    186 			} else {
    187 				nent++;
    188 				p->n_value = 0;
    189 				p->n_type = 0;
    190 			}
    191 		}
    192 		return nent;
    193 	}
    194 
    195 	mappedsize = (size_t)st.st_size;
    196 	mappedfile = mmap(NULL, mappedsize, PROT_READ, MAP_PRIVATE|MAP_FILE,
    197 	    fd, (off_t)0);
    198 	if (mappedfile == (char *)-1)
    199 		BAD;
    200 
    201 	/*
    202 	 * Make sure we can access the executable's header
    203 	 * directly, and make sure the recognize the executable
    204 	 * as an ELF binary.
    205 	 */
    206 	if (check(0, sizeof *ehdrp))
    207 		BADUNMAP;
    208 	ehdrp = (Elf_Ehdr *)(void *)&mappedfile[0];
    209 
    210 	/*
    211 	 * Find the symbol list and string table.
    212 	 */
    213 	nshdr = ehdrp->e_shnum;
    214 	shdr_off = ehdrp->e_shoff;
    215 	shdr_size = ehdrp->e_shentsize * nshdr;
    216 
    217 	if (check(shdr_off, shdr_size) ||
    218 	    (sizeof *shdrp != ehdrp->e_shentsize))
    219 		BADUNMAP;
    220 	shdrp = (void *)&mappedfile[(size_t)shdr_off];
    221 
    222 	for (i = 0; i < nshdr; i++) {
    223 		if (shdrp[i].sh_type == SHT_SYMTAB) {
    224 			symshdrp = &shdrp[i];
    225 			symstrshdrp = &shdrp[shdrp[i].sh_link];
    226 		}
    227 	}
    228 
    229 	/* Make sure we're not stripped. */
    230 	if (symshdrp == NULL || symshdrp->sh_offset == 0)
    231 		BADUNMAP;
    232 
    233 	/* Make sure the symbols and strings are safely mapped. */
    234 	if (check(symshdrp->sh_offset, symshdrp->sh_size))
    235 		BADUNMAP;
    236 	if (check(symstrshdrp->sh_offset, symstrshdrp->sh_size))
    237 		BADUNMAP;
    238 
    239 	symp = (void *)&mappedfile[(size_t)symshdrp->sh_offset];
    240 	nsyms = (size_t)(symshdrp->sh_size / sizeof(*symp));
    241 	strtab = &mappedfile[(size_t)symstrshdrp->sh_offset];
    242 
    243 	/*
    244 	 * Clean out any left-over information for all valid entries.
    245 	 * Type and value are defined to be 0 if not found; historical
    246 	 * versions cleared other and desc as well.
    247 	 *
    248 	 * XXX Clearing anything other than n_type and n_value violates
    249 	 * the semantics given in the man page.
    250 	 */
    251 	nent = 0;
    252 	for (p = list; !ISLAST(p); ++p) {
    253 		p->n_type = 0;
    254 		p->n_other = 0;
    255 		p->n_desc = 0;
    256 		p->n_value = 0;
    257 		++nent;
    258 	}
    259 
    260 	for (i = 0; i < nsyms; i++) {
    261 		for (p = list; !ISLAST(p); ++p) {
    262 			const char *nlistname;
    263 			char *symtabname;
    264 
    265 			/* This may be incorrect */
    266 			nlistname = N_NAME(p);
    267 			if (*nlistname == '_')
    268 				nlistname++;
    269 
    270 			symtabname = &strtab[symp[i].st_name];
    271 
    272 			if (!strcmp(symtabname, nlistname)) {
    273 				/*
    274 				 * Translate (roughly) from ELF to nlist
    275 				 */
    276 				p->n_value = (uintptr_t)symp[i].st_value;
    277 				switch (ELF_ST_TYPE(symp[i].st_info)) {
    278 				case STT_NOTYPE:
    279 					p->n_type = N_UNDF;
    280 					break;
    281 				case STT_OBJECT:
    282 				case STT_COMMON:
    283 					p->n_type = N_DATA;
    284 					break;
    285 				case STT_FUNC:
    286 					p->n_type = N_TEXT;
    287 					break;
    288 				case STT_FILE:
    289 					p->n_type = N_FN;
    290 					break;
    291 				default:
    292 					/* catch other enumerations for gcc */
    293 					break;
    294 				}
    295 				if (ELF_ST_BIND(symp[i].st_info) != STB_LOCAL)
    296 					p->n_type |= N_EXT;
    297 				p->n_desc = 0;			/* XXX */
    298 				p->n_other = 0;			/* XXX */
    299 
    300 				if (--nent <= 0)
    301 					goto done;
    302 				break;	/* into next run of outer loop */
    303 			}
    304 		}
    305 	}
    306 
    307 done:
    308 	rv = nent;
    309 unmap:
    310 	munmap(mappedfile, mappedsize);
    311 #endif /* _LP64 || ELFSIZE == 32 */
    312 out:
    313 	return (rv);
    314 }
    315 
    316 #endif
    317