summaryrefslogtreecommitdiff
path: root/sftp-realpath.c
diff options
context:
space:
mode:
Diffstat (limited to 'sftp-realpath.c')
-rw-r--r--sftp-realpath.c226
1 files changed, 226 insertions, 0 deletions
diff --git a/sftp-realpath.c b/sftp-realpath.c
new file mode 100644
index 000000000..9ac401812
--- /dev/null
+++ b/sftp-realpath.c
@@ -0,0 +1,226 @@
1/* $OpenBSD: sftp-realpath.c,v 1.1 2019/07/05 04:55:40 djm Exp $ */
2/*
3 * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
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 * 3. The names of the authors may not be used to endorse or promote
14 * products derived from this software without specific prior written
15 * permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include "includes.h"
31
32#include <sys/types.h>
33#include <sys/param.h>
34#include <sys/stat.h>
35
36#include <errno.h>
37#include <stdlib.h>
38#include <stddef.h>
39#include <string.h>
40#include <unistd.h>
41#include <limits.h>
42
43#ifndef SYMLOOP_MAX
44# define SYMLOOP_MAX 32
45#endif
46
47/* XXX rewrite sftp-server to use POSIX realpath and remove this hack */
48
49char *sftp_realpath(const char *path, char *resolved);
50
51/*
52 * char *realpath(const char *path, char resolved[PATH_MAX]);
53 *
54 * Find the real name of path, by removing all ".", ".." and symlink
55 * components. Returns (resolved) on success, or (NULL) on failure,
56 * in which case the path which caused trouble is left in (resolved).
57 */
58char *
59sftp_realpath(const char *path, char *resolved)
60{
61 struct stat sb;
62 char *p, *q, *s;
63 size_t left_len, resolved_len;
64 unsigned symlinks;
65 int serrno, slen, mem_allocated;
66 char left[PATH_MAX], next_token[PATH_MAX], symlink[PATH_MAX];
67
68 if (path[0] == '\0') {
69 errno = ENOENT;
70 return (NULL);
71 }
72
73 serrno = errno;
74
75 if (resolved == NULL) {
76 resolved = malloc(PATH_MAX);
77 if (resolved == NULL)
78 return (NULL);
79 mem_allocated = 1;
80 } else
81 mem_allocated = 0;
82
83 symlinks = 0;
84 if (path[0] == '/') {
85 resolved[0] = '/';
86 resolved[1] = '\0';
87 if (path[1] == '\0')
88 return (resolved);
89 resolved_len = 1;
90 left_len = strlcpy(left, path + 1, sizeof(left));
91 } else {
92 if (getcwd(resolved, PATH_MAX) == NULL) {
93 if (mem_allocated)
94 free(resolved);
95 else
96 strlcpy(resolved, ".", PATH_MAX);
97 return (NULL);
98 }
99 resolved_len = strlen(resolved);
100 left_len = strlcpy(left, path, sizeof(left));
101 }
102 if (left_len >= sizeof(left) || resolved_len >= PATH_MAX) {
103 errno = ENAMETOOLONG;
104 goto err;
105 }
106
107 /*
108 * Iterate over path components in `left'.
109 */
110 while (left_len != 0) {
111 /*
112 * Extract the next path component and adjust `left'
113 * and its length.
114 */
115 p = strchr(left, '/');
116 s = p ? p : left + left_len;
117 if (s - left >= (ptrdiff_t)sizeof(next_token)) {
118 errno = ENAMETOOLONG;
119 goto err;
120 }
121 memcpy(next_token, left, s - left);
122 next_token[s - left] = '\0';
123 left_len -= s - left;
124 if (p != NULL)
125 memmove(left, s + 1, left_len + 1);
126 if (resolved[resolved_len - 1] != '/') {
127 if (resolved_len + 1 >= PATH_MAX) {
128 errno = ENAMETOOLONG;
129 goto err;
130 }
131 resolved[resolved_len++] = '/';
132 resolved[resolved_len] = '\0';
133 }
134 if (next_token[0] == '\0')
135 continue;
136 else if (strcmp(next_token, ".") == 0)
137 continue;
138 else if (strcmp(next_token, "..") == 0) {
139 /*
140 * Strip the last path component except when we have
141 * single "/"
142 */
143 if (resolved_len > 1) {
144 resolved[resolved_len - 1] = '\0';
145 q = strrchr(resolved, '/') + 1;
146 *q = '\0';
147 resolved_len = q - resolved;
148 }
149 continue;
150 }
151
152 /*
153 * Append the next path component and lstat() it. If
154 * lstat() fails we still can return successfully if
155 * there are no more path components left.
156 */
157 resolved_len = strlcat(resolved, next_token, PATH_MAX);
158 if (resolved_len >= PATH_MAX) {
159 errno = ENAMETOOLONG;
160 goto err;
161 }
162 if (lstat(resolved, &sb) != 0) {
163 if (errno == ENOENT && p == NULL) {
164 errno = serrno;
165 return (resolved);
166 }
167 goto err;
168 }
169 if (S_ISLNK(sb.st_mode)) {
170 if (symlinks++ > SYMLOOP_MAX) {
171 errno = ELOOP;
172 goto err;
173 }
174 slen = readlink(resolved, symlink, sizeof(symlink) - 1);
175 if (slen < 0)
176 goto err;
177 symlink[slen] = '\0';
178 if (symlink[0] == '/') {
179 resolved[1] = 0;
180 resolved_len = 1;
181 } else if (resolved_len > 1) {
182 /* Strip the last path component. */
183 resolved[resolved_len - 1] = '\0';
184 q = strrchr(resolved, '/') + 1;
185 *q = '\0';
186 resolved_len = q - resolved;
187 }
188
189 /*
190 * If there are any path components left, then
191 * append them to symlink. The result is placed
192 * in `left'.
193 */
194 if (p != NULL) {
195 if (symlink[slen - 1] != '/') {
196 if (slen + 1 >=
197 (ptrdiff_t)sizeof(symlink)) {
198 errno = ENAMETOOLONG;
199 goto err;
200 }
201 symlink[slen] = '/';
202 symlink[slen + 1] = 0;
203 }
204 left_len = strlcat(symlink, left, sizeof(symlink));
205 if (left_len >= sizeof(symlink)) {
206 errno = ENAMETOOLONG;
207 goto err;
208 }
209 }
210 left_len = strlcpy(left, symlink, sizeof(left));
211 }
212 }
213
214 /*
215 * Remove trailing slash except when the resolved pathname
216 * is a single "/".
217 */
218 if (resolved_len > 1 && resolved[resolved_len - 1] == '/')
219 resolved[resolved_len - 1] = '\0';
220 return (resolved);
221
222err:
223 if (mem_allocated)
224 free(resolved);
225 return (NULL);
226}