1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
|
/*
* chroot_realpath.c -- reslove pathname as if inside chroot
* Based on realpath.c Copyright (C) 1993 Rick Sladkey <jrs@world.std.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; see the file COPYING.LIB. If not,
* write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*
* 2005/09/12: Dan Howell (modified from realpath.c to emulate chroot)
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <limits.h> /* for PATH_MAX */
#include <sys/param.h> /* for MAXPATHLEN */
#include <errno.h>
#ifndef __set_errno
#define __set_errno(val) ((errno) = (val))
#endif
#include <sys/stat.h> /* for S_IFLNK */
#ifndef PATH_MAX
#define PATH_MAX _POSIX_PATH_MAX
#endif
#define MAX_READLINKS 32
char *chroot_realpath(const char *chroot, const char *path,
char resolved_path[])
{
char copy_path[PATH_MAX];
char link_path[PATH_MAX];
char got_path[PATH_MAX];
char *got_path_root = got_path;
char *new_path = got_path;
char *max_path;
int readlinks = 0;
int n;
int chroot_len;
/* Trivial case. */
if (chroot == NULL || *chroot == '\0' ||
(*chroot == '/' && chroot[1] == '\0')) {
strcpy(resolved_path, path);
return resolved_path;
}
chroot_len = strlen(chroot);
if (chroot_len + strlen(path) >= PATH_MAX - 3) {
__set_errno(ENAMETOOLONG);
return NULL;
}
/* Make a copy of the source path since we may need to modify it. */
strcpy(copy_path, path);
path = copy_path;
max_path = copy_path + PATH_MAX - chroot_len - 3;
/* Start with the chroot path. */
strcpy(new_path, chroot);
new_path += chroot_len;
while (*new_path == '/' && new_path > got_path)
new_path--;
got_path_root = new_path;
*new_path++ = '/';
/* Expand each slash-separated pathname component. */
while (*path != '\0') {
/* Ignore stray "/". */
if (*path == '/') {
path++;
continue;
}
if (*path == '.') {
/* Ignore ".". */
if (path[1] == '\0' || path[1] == '/') {
path++;
continue;
}
if (path[1] == '.') {
if (path[2] == '\0' || path[2] == '/') {
path += 2;
/* Ignore ".." at root. */
if (new_path == got_path_root + 1)
continue;
/* Handle ".." by backing up. */
while ((--new_path)[-1] != '/') ;
continue;
}
}
}
/* Safely copy the next pathname component. */
while (*path != '\0' && *path != '/') {
if (path > max_path) {
__set_errno(ENAMETOOLONG);
return NULL;
}
*new_path++ = *path++;
}
if (*path == '\0')
/* Don't follow symlink for last pathname component. */
break;
#ifdef S_IFLNK
/* Protect against infinite loops. */
if (readlinks++ > MAX_READLINKS) {
__set_errno(ELOOP);
return NULL;
}
/* See if latest pathname component is a symlink. */
*new_path = '\0';
n = readlink(got_path, link_path, PATH_MAX - 1);
if (n < 0) {
/* EINVAL means the file exists but isn't a symlink. */
if (errno != EINVAL) {
/* Make sure it's null terminated. */
*new_path = '\0';
strcpy(resolved_path, got_path);
return NULL;
}
} else {
/* Note: readlink doesn't add the null byte. */
link_path[n] = '\0';
if (*link_path == '/')
/* Start over for an absolute symlink. */
new_path = got_path_root;
else
/* Otherwise back up over this component. */
while (*(--new_path) != '/') ;
/* Safe sex check. */
if (strlen(path) + n >= PATH_MAX - 2) {
__set_errno(ENAMETOOLONG);
return NULL;
}
/* Insert symlink contents into path. */
strcat(link_path, path);
strcpy(copy_path, link_path);
path = copy_path;
}
#endif /* S_IFLNK */
*new_path++ = '/';
}
/* Delete trailing slash but don't whomp a lone slash. */
if (new_path != got_path + 1 && new_path[-1] == '/')
new_path--;
/* Make sure it's null terminated. */
*new_path = '\0';
strcpy(resolved_path, got_path);
return resolved_path;
}
|
