1 /* $NetBSD: libelf_ehdr.c,v 1.2 2014/03/09 16:58:04 christos Exp $ */
2
3 /*-
4 * Copyright (c) 2006,2008 Joseph Koshy
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 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #if HAVE_NBTOOL_CONFIG_H
30 # include "nbtool_config.h"
31 #endif
32
33 #include <sys/cdefs.h>
34
35 #include <assert.h>
36 #include <gelf.h>
37 #include <libelf.h>
38 #include <stdlib.h>
39
40 #include "_libelf.h"
41
42 __RCSID("$NetBSD: libelf_ehdr.c,v 1.2 2014/03/09 16:58:04 christos Exp $");
43 ELFTC_VCSID("Id: libelf_ehdr.c 2225 2011-11-26 18:55:54Z jkoshy ");
44
45 /*
46 * Retrieve counts for sections, phdrs and the section string table index
47 * from section header #0 of the ELF object.
48 */
49 static int
_libelf_load_extended(Elf * e,int ec,uint64_t shoff,uint16_t phnum,uint16_t strndx)50 _libelf_load_extended(Elf *e, int ec, uint64_t shoff, uint16_t phnum,
51 uint16_t strndx)
52 {
53 Elf_Scn *scn;
54 size_t fsz;
55 int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap);
56 uint32_t shtype;
57
58 assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn));
59
60 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, 1);
61 assert(fsz > 0);
62
63 if (e->e_rawsize < shoff + fsz) { /* raw file too small */
64 LIBELF_SET_ERROR(HEADER, 0);
65 return (0);
66 }
67
68 if ((scn = _libelf_allocate_scn(e, (size_t) 0)) == NULL)
69 return (0);
70
71 if (shoff > SSIZE_MAX) {
72 LIBELF_SET_ERROR(HEADER, 0);
73 return (0);
74 }
75
76 xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec);
77 (*xlator)((void *) &scn->s_shdr, sizeof(scn->s_shdr),
78 e->e_rawfile + shoff, (size_t) 1,
79 e->e_byteorder != _libelf_host_byteorder());
80
81 #define GET_SHDR_MEMBER(M) ((ec == ELFCLASS32) ? scn->s_shdr.s_shdr32.M : \
82 scn->s_shdr.s_shdr64.M)
83
84 if (GET_SHDR_MEMBER(sh_size) > UINT_MAX) {
85 LIBELF_SET_ERROR(HEADER, 0);
86 return (0);
87 }
88
89 if ((shtype = GET_SHDR_MEMBER(sh_type)) != SHT_NULL) {
90 LIBELF_SET_ERROR(SECTION, 0);
91 return (0);
92 }
93
94 e->e_u.e_elf.e_nscn = (unsigned int)GET_SHDR_MEMBER(sh_size);
95 e->e_u.e_elf.e_nphdr = (phnum != PN_XNUM) ? phnum :
96 GET_SHDR_MEMBER(sh_info);
97 e->e_u.e_elf.e_strndx = (strndx != SHN_XINDEX) ? strndx :
98 GET_SHDR_MEMBER(sh_link);
99 #undef GET_SHDR_MEMBER
100
101 return (1);
102 }
103
104 #define EHDR_INIT(E,SZ) do { \
105 Elf##SZ##_Ehdr *eh = (E); \
106 eh->e_ident[EI_MAG0] = ELFMAG0; \
107 eh->e_ident[EI_MAG1] = ELFMAG1; \
108 eh->e_ident[EI_MAG2] = ELFMAG2; \
109 eh->e_ident[EI_MAG3] = ELFMAG3; \
110 eh->e_ident[EI_CLASS] = ELFCLASS##SZ; \
111 eh->e_ident[EI_DATA] = ELFDATANONE; \
112 eh->e_ident[EI_VERSION] = LIBELF_PRIVATE(version); \
113 eh->e_machine = EM_NONE; \
114 eh->e_type = ELF_K_NONE; \
115 eh->e_version = LIBELF_PRIVATE(version); \
116 } while (/*CONSTCOND*/0)
117
118 void *
_libelf_ehdr(Elf * e,int ec,int allocate)119 _libelf_ehdr(Elf *e, int ec, int allocate)
120 {
121 void *ehdr;
122 size_t fsz, msz;
123 uint16_t phnum, shnum, strndx;
124 uint64_t shoff;
125 int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap);
126
127 assert(ec == ELFCLASS32 || ec == ELFCLASS64);
128
129 if (e == NULL || e->e_kind != ELF_K_ELF) {
130 LIBELF_SET_ERROR(ARGUMENT, 0);
131 return (NULL);
132 }
133
134 if (e->e_class != ELFCLASSNONE && e->e_class != ec) {
135 LIBELF_SET_ERROR(CLASS, 0);
136 return (NULL);
137 }
138
139 if (e->e_version != EV_CURRENT) {
140 LIBELF_SET_ERROR(VERSION, 0);
141 return (NULL);
142 }
143
144 if (e->e_class == ELFCLASSNONE)
145 e->e_class = ec;
146
147 if (ec == ELFCLASS32)
148 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr32;
149 else
150 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr64;
151
152 if (ehdr != NULL) /* already have a translated ehdr */
153 return (ehdr);
154
155 fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1);
156 assert(fsz > 0);
157
158 if (e->e_cmd != ELF_C_WRITE && e->e_rawsize < fsz) {
159 LIBELF_SET_ERROR(HEADER, 0);
160 return (NULL);
161 }
162
163 msz = _libelf_msize(ELF_T_EHDR, ec, EV_CURRENT);
164
165 assert(msz > 0);
166
167 if ((ehdr = calloc((size_t) 1, msz)) == NULL) {
168 LIBELF_SET_ERROR(RESOURCE, 0);
169 return (NULL);
170 }
171
172 if (ec == ELFCLASS32) {
173 e->e_u.e_elf.e_ehdr.e_ehdr32 = ehdr;
174 EHDR_INIT(ehdr,32);
175 } else {
176 e->e_u.e_elf.e_ehdr.e_ehdr64 = ehdr;
177 EHDR_INIT(ehdr,64);
178 }
179
180 if (allocate)
181 e->e_flags |= ELF_F_DIRTY;
182
183 if (e->e_cmd == ELF_C_WRITE)
184 return (ehdr);
185
186 xlator = _libelf_get_translator(ELF_T_EHDR, ELF_TOMEMORY, ec);
187 (*xlator)(ehdr, msz, e->e_rawfile, (size_t) 1,
188 e->e_byteorder != _libelf_host_byteorder());
189
190 /*
191 * If extended numbering is being used, read the correct
192 * number of sections and program header entries.
193 */
194 if (ec == ELFCLASS32) {
195 phnum = ((Elf32_Ehdr *) ehdr)->e_phnum;
196 shnum = ((Elf32_Ehdr *) ehdr)->e_shnum;
197 shoff = ((Elf32_Ehdr *) ehdr)->e_shoff;
198 strndx = ((Elf32_Ehdr *) ehdr)->e_shstrndx;
199 } else {
200 phnum = ((Elf64_Ehdr *) ehdr)->e_phnum;
201 shnum = ((Elf64_Ehdr *) ehdr)->e_shnum;
202 shoff = ((Elf64_Ehdr *) ehdr)->e_shoff;
203 strndx = ((Elf64_Ehdr *) ehdr)->e_shstrndx;
204 }
205
206 if (shnum >= SHN_LORESERVE ||
207 (shoff == 0LL && (shnum != 0 || phnum == PN_XNUM ||
208 strndx == SHN_XINDEX))) {
209 LIBELF_SET_ERROR(HEADER, 0);
210 return (NULL);
211 }
212
213 if (shnum != 0 || shoff == 0LL) { /* not using extended numbering */
214 e->e_u.e_elf.e_nphdr = phnum;
215 e->e_u.e_elf.e_nscn = shnum;
216 e->e_u.e_elf.e_strndx = strndx;
217 } else if (_libelf_load_extended(e, ec, shoff, phnum, strndx) == 0)
218 return (NULL);
219
220 return (ehdr);
221 }
222