1 /*-
2 * Copyright (c) 2006,2008 Joseph Koshy
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #include <assert.h>
28 #include <gelf.h>
29 #include <libelf.h>
30 #include <stdlib.h>
31
32 #include "_libelf.h"
33
34 ELFTC_VCSID("$Id: libelf_ehdr.c 3174 2015-03-27 17:13:41Z emaste $");
35
36 /*
37 * Retrieve counts for sections, phdrs and the section string table index
38 * from section header #0 of the ELF object.
39 */
40 static int
_libelf_load_extended(Elf * e,int ec,uint64_t shoff,uint16_t phnum,uint16_t strndx)41 _libelf_load_extended(Elf *e, int ec, uint64_t shoff, uint16_t phnum,
42 uint16_t strndx)
43 {
44 Elf_Scn *scn;
45 size_t fsz;
46 int (*xlator)(unsigned char *_d, size_t _dsz, unsigned char *_s,
47 size_t _c, int _swap);
48 uint32_t shtype;
49
50 assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn));
51
52 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, 1);
53 assert(fsz > 0);
54
55 if (e->e_rawsize < shoff + fsz) { /* raw file too small */
56 LIBELF_SET_ERROR(HEADER, 0);
57 return (0);
58 }
59
60 if ((scn = _libelf_allocate_scn(e, (size_t) 0)) == NULL)
61 return (0);
62
63 xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec);
64 (*xlator)((unsigned char *) &scn->s_shdr, sizeof(scn->s_shdr),
65 (unsigned char *) e->e_rawfile + shoff, (size_t) 1,
66 e->e_byteorder != LIBELF_PRIVATE(byteorder));
67
68 #define GET_SHDR_MEMBER(M) ((ec == ELFCLASS32) ? scn->s_shdr.s_shdr32.M : \
69 scn->s_shdr.s_shdr64.M)
70
71 if ((shtype = GET_SHDR_MEMBER(sh_type)) != SHT_NULL) {
72 LIBELF_SET_ERROR(SECTION, 0);
73 return (0);
74 }
75
76 e->e_u.e_elf.e_nscn = (size_t) GET_SHDR_MEMBER(sh_size);
77 e->e_u.e_elf.e_nphdr = (phnum != PN_XNUM) ? phnum :
78 GET_SHDR_MEMBER(sh_info);
79 e->e_u.e_elf.e_strndx = (strndx != SHN_XINDEX) ? strndx :
80 GET_SHDR_MEMBER(sh_link);
81 #undef GET_SHDR_MEMBER
82
83 return (1);
84 }
85
86 #define EHDR_INIT(E,SZ) do { \
87 Elf##SZ##_Ehdr *eh = (E); \
88 eh->e_ident[EI_MAG0] = ELFMAG0; \
89 eh->e_ident[EI_MAG1] = ELFMAG1; \
90 eh->e_ident[EI_MAG2] = ELFMAG2; \
91 eh->e_ident[EI_MAG3] = ELFMAG3; \
92 eh->e_ident[EI_CLASS] = ELFCLASS##SZ; \
93 eh->e_ident[EI_DATA] = ELFDATANONE; \
94 eh->e_ident[EI_VERSION] = LIBELF_PRIVATE(version) & 0xFFU; \
95 eh->e_machine = EM_NONE; \
96 eh->e_type = ELF_K_NONE; \
97 eh->e_version = LIBELF_PRIVATE(version); \
98 } while (0)
99
100 void *
_libelf_ehdr(Elf * e,int ec,int allocate)101 _libelf_ehdr(Elf *e, int ec, int allocate)
102 {
103 void *ehdr;
104 size_t fsz, msz;
105 uint16_t phnum, shnum, strndx;
106 uint64_t shoff;
107 int (*xlator)(unsigned char *_d, size_t _dsz, unsigned char *_s,
108 size_t _c, int _swap);
109
110 assert(ec == ELFCLASS32 || ec == ELFCLASS64);
111
112 if (e == NULL || e->e_kind != ELF_K_ELF) {
113 LIBELF_SET_ERROR(ARGUMENT, 0);
114 return (NULL);
115 }
116
117 if (e->e_class != ELFCLASSNONE && e->e_class != ec) {
118 LIBELF_SET_ERROR(CLASS, 0);
119 return (NULL);
120 }
121
122 if (e->e_version != EV_CURRENT) {
123 LIBELF_SET_ERROR(VERSION, 0);
124 return (NULL);
125 }
126
127 if (e->e_class == ELFCLASSNONE)
128 e->e_class = ec;
129
130 if (ec == ELFCLASS32)
131 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr32;
132 else
133 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr64;
134
135 if (ehdr != NULL) /* already have a translated ehdr */
136 return (ehdr);
137
138 fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1);
139 assert(fsz > 0);
140
141 if (e->e_cmd != ELF_C_WRITE && e->e_rawsize < fsz) {
142 LIBELF_SET_ERROR(HEADER, 0);
143 return (NULL);
144 }
145
146 msz = _libelf_msize(ELF_T_EHDR, ec, EV_CURRENT);
147
148 assert(msz > 0);
149
150 if ((ehdr = calloc((size_t) 1, msz)) == NULL) {
151 LIBELF_SET_ERROR(RESOURCE, 0);
152 return (NULL);
153 }
154
155 if (ec == ELFCLASS32) {
156 e->e_u.e_elf.e_ehdr.e_ehdr32 = ehdr;
157 EHDR_INIT(ehdr,32);
158 } else {
159 e->e_u.e_elf.e_ehdr.e_ehdr64 = ehdr;
160 EHDR_INIT(ehdr,64);
161 }
162
163 if (allocate)
164 e->e_flags |= ELF_F_DIRTY;
165
166 if (e->e_cmd == ELF_C_WRITE)
167 return (ehdr);
168
169 xlator = _libelf_get_translator(ELF_T_EHDR, ELF_TOMEMORY, ec);
170 (*xlator)((unsigned char*) ehdr, msz, e->e_rawfile, (size_t) 1,
171 e->e_byteorder != LIBELF_PRIVATE(byteorder));
172
173 /*
174 * If extended numbering is being used, read the correct
175 * number of sections and program header entries.
176 */
177 if (ec == ELFCLASS32) {
178 phnum = ((Elf32_Ehdr *) ehdr)->e_phnum;
179 shnum = ((Elf32_Ehdr *) ehdr)->e_shnum;
180 shoff = ((Elf32_Ehdr *) ehdr)->e_shoff;
181 strndx = ((Elf32_Ehdr *) ehdr)->e_shstrndx;
182 } else {
183 phnum = ((Elf64_Ehdr *) ehdr)->e_phnum;
184 shnum = ((Elf64_Ehdr *) ehdr)->e_shnum;
185 shoff = ((Elf64_Ehdr *) ehdr)->e_shoff;
186 strndx = ((Elf64_Ehdr *) ehdr)->e_shstrndx;
187 }
188
189 if (shnum >= SHN_LORESERVE ||
190 (shoff == 0LL && (shnum != 0 || phnum == PN_XNUM ||
191 strndx == SHN_XINDEX))) {
192 LIBELF_SET_ERROR(HEADER, 0);
193 return (NULL);
194 }
195
196 if (shnum != 0 || shoff == 0LL) { /* not using extended numbering */
197 e->e_u.e_elf.e_nphdr = phnum;
198 e->e_u.e_elf.e_nscn = shnum;
199 e->e_u.e_elf.e_strndx = strndx;
200 } else if (_libelf_load_extended(e, ec, shoff, phnum, strndx) == 0)
201 return (NULL);
202
203 return (ehdr);
204 }
205