Branch data Line data Source code
1 : : /* Update data structures for changes and write them out.
2 : : Copyright (C) 1999, 2000, 2001, 2002, 2004, 2005, 2006, 2015 Red Hat, Inc.
3 : : This file is part of elfutils.
4 : : Contributed by Ulrich Drepper <drepper@redhat.com>, 1999.
5 : :
6 : : This file is free software; you can redistribute it and/or modify
7 : : it under the terms of either
8 : :
9 : : * the GNU Lesser General Public License as published by the Free
10 : : Software Foundation; either version 3 of the License, or (at
11 : : your option) any later version
12 : :
13 : : or
14 : :
15 : : * the GNU General Public License as published by the Free
16 : : Software Foundation; either version 2 of the License, or (at
17 : : your option) any later version
18 : :
19 : : or both in parallel, as here.
20 : :
21 : : elfutils is distributed in the hope that it will be useful, but
22 : : WITHOUT ANY WARRANTY; without even the implied warranty of
23 : : MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
24 : : General Public License for more details.
25 : :
26 : : You should have received copies of the GNU General Public License and
27 : : the GNU Lesser General Public License along with this program. If
28 : : not, see <http://www.gnu.org/licenses/>. */
29 : :
30 : : #ifdef HAVE_CONFIG_H
31 : : # include <config.h>
32 : : #endif
33 : :
34 : : #include <libelf.h>
35 : : #include <fcntl.h>
36 : : #include <sys/stat.h>
37 : :
38 : : #include "libelfP.h"
39 : :
40 : :
41 : : static int64_t
42 : 1262 : write_file (Elf *elf, int64_t size, int change_bo, size_t shnum)
43 : : {
44 : 1262 : int class = elf->class;
45 : :
46 : : /* Check the mode bits now, before modification might change them. */
47 : 1262 : struct stat st;
48 [ - + ]: 1262 : if (unlikely (fstat (elf->fildes, &st) != 0))
49 : : {
50 : 0 : __libelf_seterrno (ELF_E_WRITE_ERROR);
51 : 0 : return -1;
52 : : }
53 : :
54 : : /* Adjust the size in any case. We do this even if we use `write'.
55 : : We cannot do this if this file is in an archive. We also don't
56 : : do it *now* if we are shortening the file since this would
57 : : prevent programs to use the data of the file in generating the
58 : : new file. We truncate the file later in this case. */
59 [ + - ]: 1262 : if (elf->parent == NULL
60 [ + - ]: 1262 : && (elf->maximum_size == ~((size_t) 0)
61 [ + + ]: 1262 : || (size_t) size > elf->maximum_size)
62 [ - + ]: 1148 : && unlikely (ftruncate (elf->fildes, size) != 0))
63 : : {
64 : 0 : __libelf_seterrno (ELF_E_WRITE_ERROR);
65 : 0 : return -1;
66 : : }
67 : :
68 : : /* Try to map the file if this isn't done yet. */
69 [ + + + + ]: 1262 : if (elf->map_address == NULL && elf->cmd == ELF_C_WRITE_MMAP)
70 : : {
71 : 254 : elf->map_address = mmap (NULL, size, PROT_READ | PROT_WRITE,
72 : : MAP_SHARED, elf->fildes, 0);
73 [ - + ]: 254 : if (unlikely (elf->map_address == MAP_FAILED))
74 : 0 : elf->map_address = NULL;
75 : : else
76 : 254 : elf->flags |= ELF_F_MMAPPED;
77 : : }
78 : :
79 [ + + ]: 1262 : if (elf->map_address != NULL)
80 : : {
81 : : /* When using mmap we want to make sure the file content is
82 : : really there. Only using ftruncate might mean the file is
83 : : extended, but space isn't allocated yet. This might cause a
84 : : SIGBUS once we write into the mmapped space and the disk is
85 : : full. In glibc posix_fallocate is required to extend the
86 : : file and allocate enough space even if the underlying
87 : : filesystem would normally return EOPNOTSUPP. But other
88 : : implementations might not work as expected. And the glibc
89 : : fallback case might fail (with unexpected errnos) in some cases.
90 : : So we only report an error when the call fails and errno is
91 : : ENOSPC. Otherwise we ignore the error and treat it as just hint. */
92 [ + - ]: 286 : if (elf->parent == NULL
93 [ + - ]: 286 : && (elf->maximum_size == ~((size_t) 0)
94 [ + + ]: 286 : || (size_t) size > elf->maximum_size))
95 : : {
96 [ - + ]: 282 : if (unlikely (posix_fallocate (elf->fildes, 0, size) != 0))
97 [ # # ]: 0 : if (errno == ENOSPC)
98 : : {
99 : 0 : __libelf_seterrno (ELF_E_WRITE_ERROR);
100 : 0 : return -1;
101 : : }
102 : :
103 : : /* Extend the mmap address if needed. */
104 [ + + ]: 282 : if (elf->cmd == ELF_C_RDWR_MMAP
105 [ + - ]: 28 : && (size_t) size > elf->maximum_size)
106 : : {
107 : : #ifdef HAVE_MREMAP
108 [ - + ]: 28 : if (mremap (elf->map_address, elf->maximum_size,
109 : : size, 0) == MAP_FAILED)
110 : : #endif
111 : : {
112 : 0 : __libelf_seterrno (ELF_E_WRITE_ERROR);
113 : 0 : return -1;
114 : : }
115 : 28 : elf->maximum_size = size;
116 : : }
117 : :
118 : : }
119 : :
120 : : /* The file is mmaped. */
121 [ + - ]: 286 : if ((class == ELFCLASS32
122 : 132 : ? __elf32_updatemmap (elf, change_bo, shnum)
123 [ + + ]: 418 : : __elf64_updatemmap (elf, change_bo, shnum)) != 0)
124 : : /* Some problem while writing. */
125 : : size = -1;
126 : : }
127 : : else
128 : : {
129 : : /* The file is not mmaped. */
130 [ - + ]: 976 : if ((class == ELFCLASS32
131 : 396 : ? __elf32_updatefile (elf, change_bo, shnum)
132 [ + + ]: 1372 : : __elf64_updatefile (elf, change_bo, shnum)) != 0)
133 : : /* Some problem while writing. */
134 : : size = -1;
135 : : }
136 : :
137 : : /* Reduce the file size if necessary. */
138 [ - + ]: 1262 : if (size != -1
139 [ + - ]: 1262 : && elf->parent == NULL
140 [ + - ]: 1262 : && elf->maximum_size != ~((size_t) 0)
141 [ + + ]: 1262 : && (size_t) size < elf->maximum_size
142 [ - + ]: 82 : && unlikely (ftruncate (elf->fildes, size) != 0))
143 : : {
144 : 0 : __libelf_seterrno (ELF_E_WRITE_ERROR);
145 : 0 : size = -1;
146 : : }
147 : :
148 : : /* POSIX says that ftruncate and write may clear the S_ISUID and S_ISGID
149 : : mode bits. So make sure we restore them afterwards if they were set.
150 : : This is not atomic if someone else chmod's the file while we operate. */
151 [ - + ]: 1262 : if (size != -1
152 [ - + ]: 1262 : && unlikely (st.st_mode & (S_ISUID | S_ISGID))
153 : : /* fchmod ignores the bits we cannot change. */
154 [ # # ]: 0 : && unlikely (fchmod (elf->fildes, st.st_mode) != 0))
155 : : {
156 : 0 : __libelf_seterrno (ELF_E_WRITE_ERROR);
157 : 0 : size = -1;
158 : : }
159 : :
160 [ - + ]: 1262 : if (size != -1 && elf->parent == NULL)
161 : 1262 : elf->maximum_size = size;
162 : :
163 : : return size;
164 : : }
165 : :
166 : :
167 : : int64_t
168 : 1400 : elf_update (Elf *elf, Elf_Cmd cmd)
169 : : {
170 : 1400 : size_t shnum;
171 : 1400 : int64_t size;
172 : 1400 : int change_bo = 0;
173 : :
174 : 1400 : if (cmd != ELF_C_NULL
175 [ + + ]: 1400 : && cmd != ELF_C_WRITE
176 [ - + ]: 18 : && unlikely (cmd != ELF_C_WRITE_MMAP))
177 : : {
178 : 0 : __libelf_seterrno (ELF_E_INVALID_CMD);
179 : 0 : return -1;
180 : : }
181 : :
182 [ - + ]: 1400 : if (elf == NULL)
183 : : return -1;
184 : :
185 [ - + ]: 1400 : if (elf->kind != ELF_K_ELF)
186 : : {
187 : 0 : __libelf_seterrno (ELF_E_INVALID_HANDLE);
188 : 0 : return -1;
189 : : }
190 : :
191 : 1400 : rwlock_wrlock (elf->lock);
192 : :
193 : : /* Make sure we have an ELF header. */
194 [ - + ]: 1400 : if (elf->state.elf.ehdr == NULL)
195 : : {
196 : 0 : __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);
197 : 0 : size = -1;
198 : 0 : goto out;
199 : : }
200 : :
201 : : /* Determine the number of sections. */
202 : 2800 : shnum = (elf->state.elf.scns_last->cnt == 0
203 : : ? 0
204 [ + + ]: 1400 : : 1 + elf->state.elf.scns_last->data[elf->state.elf.scns_last->cnt - 1].index);
205 : :
206 : : /* Update the ELF descriptor. First, place the program header. It
207 : : will come right after the ELF header. The count the size of all
208 : : sections and finally place the section table. */
209 : 2800 : size = (elf->class == ELFCLASS32
210 : 598 : ? __elf32_updatenull_wrlock (elf, &change_bo, shnum)
211 [ + + ]: 1400 : : __elf64_updatenull_wrlock (elf, &change_bo, shnum));
212 [ - + ]: 1400 : if (likely (size != -1)
213 : : /* See whether we actually have to write out the data. */
214 [ + + ]: 1400 : && (cmd == ELF_C_WRITE || cmd == ELF_C_WRITE_MMAP))
215 : : {
216 : 1262 : if (elf->cmd != ELF_C_RDWR
217 [ + + ]: 1262 : && elf->cmd != ELF_C_RDWR_MMAP
218 [ + + ]: 1036 : && elf->cmd != ELF_C_WRITE
219 [ - + ]: 254 : && unlikely (elf->cmd != ELF_C_WRITE_MMAP))
220 : : {
221 : 0 : __libelf_seterrno (ELF_E_UPDATE_RO);
222 : 0 : size = -1;
223 : : }
224 [ - + ]: 1262 : else if (unlikely (elf->fildes == -1))
225 : : {
226 : : /* We closed the file already. */
227 : 0 : __libelf_seterrno (ELF_E_FD_DISABLED);
228 : 0 : size = -1;
229 : : }
230 : : else
231 : 1262 : size = write_file (elf, size, change_bo, shnum);
232 : : }
233 : :
234 : 138 : out:
235 : : rwlock_unlock (elf->lock);
236 : :
237 : : return size;
238 : : }
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