1 /*-
2 * Copyright (c) 2006 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 * $FreeBSD$
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31
32 #include <assert.h>
33 #include <gelf.h>
34 #include <libelf.h>
35 #include <stdlib.h>
36
37 #include "_libelf.h"
38
39 /*
40 * Retrieve counts for sections, phdrs and the section string table index
41 * from section header #0 of the ELF object.
42 */
43 static int
_libelf_load_extended(Elf * e,int ec,uint64_t shoff,uint16_t phnum,uint16_t strndx)44 _libelf_load_extended(Elf *e, int ec, uint64_t shoff, uint16_t phnum,
45 uint16_t strndx)
46 {
47 Elf_Scn *scn;
48 size_t fsz;
49 int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap);
50 uint32_t shtype;
51
52 assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn));
53
54 fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, 1);
55 assert(fsz > 0);
56
57 if (e->e_rawsize < shoff + fsz) { /* raw file too small */
58 LIBELF_SET_ERROR(HEADER, 0);
59 return (0);
60 }
61
62 if ((scn = _libelf_allocate_scn(e, (size_t) 0)) == NULL)
63 return (0);
64
65 xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec);
66 (*xlator)((char *) &scn->s_shdr, sizeof(scn->s_shdr),
67 e->e_rawfile + shoff, (size_t) 1,
68 e->e_byteorder != LIBELF_PRIVATE(byteorder));
69
70 #define GET_SHDR_MEMBER(M) ((ec == ELFCLASS32) ? scn->s_shdr.s_shdr32.M : \
71 scn->s_shdr.s_shdr64.M)
72
73 if ((shtype = GET_SHDR_MEMBER(sh_type)) != SHT_NULL) {
74 LIBELF_SET_ERROR(SECTION, 0);
75 return (0);
76 }
77
78 e->e_u.e_elf.e_nscn = GET_SHDR_MEMBER(sh_size);
79 e->e_u.e_elf.e_nphdr = (phnum != PN_XNUM) ? phnum :
80 GET_SHDR_MEMBER(sh_info);
81 e->e_u.e_elf.e_strndx = (strndx != SHN_XINDEX) ? strndx :
82 GET_SHDR_MEMBER(sh_link);
83 #undef GET_SHDR_MEMBER
84
85 return (1);
86 }
87
88 #define EHDR_INIT(E,SZ) do { \
89 Elf##SZ##_Ehdr *eh = (E); \
90 eh->e_ident[EI_MAG0] = ELFMAG0; \
91 eh->e_ident[EI_MAG1] = ELFMAG1; \
92 eh->e_ident[EI_MAG2] = ELFMAG2; \
93 eh->e_ident[EI_MAG3] = ELFMAG3; \
94 eh->e_ident[EI_CLASS] = ELFCLASS##SZ; \
95 eh->e_ident[EI_DATA] = ELFDATANONE; \
96 eh->e_ident[EI_VERSION] = LIBELF_PRIVATE(version); \
97 eh->e_machine = EM_NONE; \
98 eh->e_type = ELF_K_NONE; \
99 eh->e_version = LIBELF_PRIVATE(version); \
100 } while (0)
101
102 void *
_libelf_ehdr(Elf * e,int ec,int allocate)103 _libelf_ehdr(Elf *e, int ec, int allocate)
104 {
105 void *ehdr;
106 size_t fsz, msz;
107 uint16_t phnum, shnum, strndx;
108 uint64_t shoff;
109 int (*xlator)(char *_d, size_t _dsz, char *_s, size_t _c, int _swap);
110
111 assert(ec == ELFCLASS32 || ec == ELFCLASS64);
112
113 if (e == NULL || e->e_kind != ELF_K_ELF) {
114 LIBELF_SET_ERROR(ARGUMENT, 0);
115 return (NULL);
116 }
117
118 if (e->e_class != ELFCLASSNONE && e->e_class != ec) {
119 LIBELF_SET_ERROR(CLASS, 0);
120 return (NULL);
121 }
122
123 if (e->e_version != EV_CURRENT) {
124 LIBELF_SET_ERROR(VERSION, 0);
125 return (NULL);
126 }
127
128 if (e->e_class == ELFCLASSNONE)
129 e->e_class = ec;
130
131 if (ec == ELFCLASS32)
132 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr32;
133 else
134 ehdr = (void *) e->e_u.e_elf.e_ehdr.e_ehdr64;
135
136 if (ehdr != NULL) /* already have a translated ehdr */
137 return (ehdr);
138
139 fsz = _libelf_fsize(ELF_T_EHDR, ec, e->e_version, (size_t) 1);
140 assert(fsz > 0);
141
142 if (e->e_cmd != ELF_C_WRITE && e->e_rawsize < fsz) {
143 LIBELF_SET_ERROR(HEADER, 0);
144 return (NULL);
145 }
146
147 msz = _libelf_msize(ELF_T_EHDR, ec, EV_CURRENT);
148
149 assert(msz > 0);
150
151 if ((ehdr = calloc((size_t) 1, msz)) == NULL) {
152 LIBELF_SET_ERROR(RESOURCE, 0);
153 return (NULL);
154 }
155
156 if (ec == ELFCLASS32) {
157 e->e_u.e_elf.e_ehdr.e_ehdr32 = ehdr;
158 EHDR_INIT(ehdr,32);
159 } else {
160 e->e_u.e_elf.e_ehdr.e_ehdr64 = ehdr;
161 EHDR_INIT(ehdr,64);
162 }
163
164 if (allocate)
165 e->e_flags |= ELF_F_DIRTY;
166
167 if (e->e_cmd == ELF_C_WRITE)
168 return (ehdr);
169
170 xlator = _libelf_get_translator(ELF_T_EHDR, ELF_TOMEMORY, ec);
171 (*xlator)(ehdr, msz, e->e_rawfile, (size_t) 1,
172 e->e_byteorder != LIBELF_PRIVATE(byteorder));
173
174 /*
175 * If extended numbering is being used, read the correct
176 * number of sections and program header entries.
177 */
178 if (ec == ELFCLASS32) {
179 phnum = ((Elf32_Ehdr *) ehdr)->e_phnum;
180 shnum = ((Elf32_Ehdr *) ehdr)->e_shnum;
181 shoff = ((Elf32_Ehdr *) ehdr)->e_shoff;
182 strndx = ((Elf32_Ehdr *) ehdr)->e_shstrndx;
183 } else {
184 phnum = ((Elf64_Ehdr *) ehdr)->e_phnum;
185 shnum = ((Elf64_Ehdr *) ehdr)->e_shnum;
186 shoff = ((Elf64_Ehdr *) ehdr)->e_shoff;
187 strndx = ((Elf64_Ehdr *) ehdr)->e_shstrndx;
188 }
189
190 if (shnum >= SHN_LORESERVE ||
191 (shoff == 0LL && (shnum != 0 || phnum == PN_XNUM ||
192 strndx == SHN_XINDEX))) {
193 LIBELF_SET_ERROR(HEADER, 0);
194 return (NULL);
195 }
196
197 if (shnum != 0 || shoff == 0LL) { /* not using extended numbering */
198 e->e_u.e_elf.e_nphdr = phnum;
199 e->e_u.e_elf.e_nscn = shnum;
200 e->e_u.e_elf.e_strndx = strndx;
201 } else if (_libelf_load_extended(e, ec, shoff, phnum, strndx) == 0)
202 return (NULL);
203
204 return (ehdr);
205 }
206