1 /* Update data structures for changes and write them out.
2 Copyright (C) 1999, 2000, 2001, 2002, 2004, 2005, 2006 Red Hat, Inc.
3 This file is part of Red Hat elfutils.
4 Contributed by Ulrich Drepper <drepper@redhat.com>, 1999.
5
6 Red Hat elfutils is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by the
8 Free Software Foundation; version 2 of the License.
9
10 Red Hat elfutils is distributed in the hope that it will be useful, but
11 WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
14
15 You should have received a copy of the GNU General Public License along
16 with Red Hat elfutils; if not, write to the Free Software Foundation,
17 Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.
18
19 In addition, as a special exception, Red Hat, Inc. gives You the
20 additional right to link the code of Red Hat elfutils with code licensed
21 under any Open Source Initiative certified open source license
22 (http://www.opensource.org/licenses/index.php) which requires the
23 distribution of source code with any binary distribution and to
24 distribute linked combinations of the two. Non-GPL Code permitted under
25 this exception must only link to the code of Red Hat elfutils through
26 those well defined interfaces identified in the file named EXCEPTION
27 found in the source code files (the "Approved Interfaces"). The files
28 of Non-GPL Code may instantiate templates or use macros or inline
29 functions from the Approved Interfaces without causing the resulting
30 work to be covered by the GNU General Public License. Only Red Hat,
31 Inc. may make changes or additions to the list of Approved Interfaces.
32 Red Hat's grant of this exception is conditioned upon your not adding
33 any new exceptions. If you wish to add a new Approved Interface or
34 exception, please contact Red Hat. You must obey the GNU General Public
35 License in all respects for all of the Red Hat elfutils code and other
36 code used in conjunction with Red Hat elfutils except the Non-GPL Code
37 covered by this exception. If you modify this file, you may extend this
38 exception to your version of the file, but you are not obligated to do
39 so. If you do not wish to provide this exception without modification,
40 you must delete this exception statement from your version and license
41 this file solely under the GPL without exception.
42
43 Red Hat elfutils is an included package of the Open Invention Network.
44 An included package of the Open Invention Network is a package for which
45 Open Invention Network licensees cross-license their patents. No patent
46 license is granted, either expressly or impliedly, by designation as an
47 included package. Should you wish to participate in the Open Invention
48 Network licensing program, please visit www.openinventionnetwork.com
49 <http://www.openinventionnetwork.com>. */
50
51 #ifdef HAVE_CONFIG_H
52 # include <config.h>
53 #endif
54
55 #include <libelf.h>
56 #include <unistd.h>
57 #include <sys/mman.h>
58 #include <sys/stat.h>
59
60 #include "libelfP.h"
61
62
63 static off_t
write_file(Elf * elf,off_t size,int change_bo,size_t shnum)64 write_file (Elf *elf, off_t size, int change_bo, size_t shnum)
65 {
66 int class = elf->class;
67
68 /* Check the mode bits now, before modification might change them. */
69 struct stat st;
70 if (unlikely (fstat (elf->fildes, &st) != 0))
71 {
72 __libelf_seterrno (ELF_E_WRITE_ERROR);
73 return -1;
74 }
75
76 /* Adjust the size in any case. We do this even if we use `write'.
77 We cannot do this if this file is in an archive. We also don't
78 do it *now* if we are shortening the file since this would
79 prevent programs to use the data of the file in generating the
80 new file. We truncate the file later in this case. */
81 if (elf->parent == NULL
82 && (elf->maximum_size == ~((size_t) 0)
83 || (size_t) size > elf->maximum_size)
84 && unlikely (ftruncate (elf->fildes, size) != 0))
85 {
86 __libelf_seterrno (ELF_E_WRITE_ERROR);
87 return -1;
88 }
89
90 /* Try to map the file if this isn't done yet. */
91 if (elf->map_address == NULL && elf->cmd == ELF_C_WRITE_MMAP)
92 {
93 #if _MUDFLAP
94 /* Mudflap doesn't grok that our mmap'd data is ok. */
95 #else
96 elf->map_address = mmap (NULL, size, PROT_READ | PROT_WRITE,
97 MAP_SHARED, elf->fildes, 0);
98 if (unlikely (elf->map_address == MAP_FAILED))
99 elf->map_address = NULL;
100 #endif
101 }
102
103 if (elf->map_address != NULL)
104 {
105 /* The file is mmaped. */
106 if ((class == ELFCLASS32
107 ? __elf32_updatemmap (elf, change_bo, shnum)
108 : __elf64_updatemmap (elf, change_bo, shnum)) != 0)
109 /* Some problem while writing. */
110 size = -1;
111 }
112 else
113 {
114 /* The file is not mmaped. */
115 if ((class == ELFCLASS32
116 ? __elf32_updatefile (elf, change_bo, shnum)
117 : __elf64_updatefile (elf, change_bo, shnum)) != 0)
118 /* Some problem while writing. */
119 size = -1;
120 }
121
122 if (size != -1
123 && elf->parent == NULL
124 && elf->maximum_size != ~((size_t) 0)
125 && (size_t) size < elf->maximum_size
126 && unlikely (ftruncate (elf->fildes, size) != 0))
127 {
128 __libelf_seterrno (ELF_E_WRITE_ERROR);
129 size = -1;
130 }
131
132 /* POSIX says that ftruncate and write may clear the S_ISUID and S_ISGID
133 mode bits. So make sure we restore them afterwards if they were set.
134 This is not atomic if someone else chmod's the file while we operate. */
135 if (size != -1
136 && unlikely (st.st_mode & (S_ISUID | S_ISGID))
137 /* fchmod ignores the bits we cannot change. */
138 && unlikely (fchmod (elf->fildes, st.st_mode) != 0))
139 {
140 __libelf_seterrno (ELF_E_WRITE_ERROR);
141 size = -1;
142 }
143
144 if (size != -1 && elf->parent == NULL)
145 elf->maximum_size = size;
146
147 return size;
148 }
149
150
151 off_t
elf_update(elf,cmd)152 elf_update (elf, cmd)
153 Elf *elf;
154 Elf_Cmd cmd;
155 {
156 size_t shnum;
157 off_t size;
158 int change_bo = 0;
159
160 if (cmd != ELF_C_NULL
161 && cmd != ELF_C_WRITE
162 && unlikely (cmd != ELF_C_WRITE_MMAP))
163 {
164 __libelf_seterrno (ELF_E_INVALID_CMD);
165 return -1;
166 }
167
168 if (elf == NULL)
169 return -1;
170
171 if (elf->kind != ELF_K_ELF)
172 {
173 __libelf_seterrno (ELF_E_INVALID_HANDLE);
174 return -1;
175 }
176
177 rwlock_wrlock (elf->lock);
178
179 /* Make sure we have an ELF header. */
180 if (elf->state.elf.ehdr == NULL)
181 {
182 __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);
183 size = -1;
184 goto out;
185 }
186
187 /* Determine the number of sections. */
188 shnum = (elf->state.elf.scns_last->cnt == 0
189 ? 0
190 : 1 + elf->state.elf.scns_last->data[elf->state.elf.scns_last->cnt - 1].index);
191
192 /* Update the ELF descriptor. First, place the program header. It
193 will come right after the ELF header. The count the size of all
194 sections and finally place the section table. */
195 size = (elf->class == ELFCLASS32
196 ? __elf32_updatenull_wrlock (elf, &change_bo, shnum)
197 : __elf64_updatenull_wrlock (elf, &change_bo, shnum));
198 if (likely (size != -1)
199 /* See whether we actually have to write out the data. */
200 && (cmd == ELF_C_WRITE || cmd == ELF_C_WRITE_MMAP))
201 {
202 if (elf->cmd != ELF_C_RDWR
203 && elf->cmd != ELF_C_RDWR_MMAP
204 && elf->cmd != ELF_C_WRITE
205 && unlikely (elf->cmd != ELF_C_WRITE_MMAP))
206 {
207 __libelf_seterrno (ELF_E_UPDATE_RO);
208 size = -1;
209 }
210 else if (unlikely (elf->fildes == -1))
211 {
212 /* We closed the file already. */
213 __libelf_seterrno (ELF_E_FD_DISABLED);
214 size = -1;
215 }
216 else
217 size = write_file (elf, size, change_bo, shnum);
218 }
219
220 out:
221 rwlock_unlock (elf->lock);
222
223 return size;
224 }
225