1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 2003 Networks Associates Technology, Inc.
5 * All rights reserved.
6 *
7 * This software was developed for the FreeBSD Project by Marshall
8 * Kirk McKusick and Network Associates Laboratories, the Security
9 * Research Division of Network Associates, Inc. under DARPA/SPAWAR
10 * contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS
11 * research program.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. The names of the authors may not be used to endorse or promote
22 * products derived from this software without specific prior written
23 * permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 *
37 * $FreeBSD: stable/12/sbin/mksnap_ffs/mksnap_ffs.c 361589 2020-05-28 17:08:39Z freqlabs $
38 */
39
40 #include <sys/param.h>
41 #include <sys/mount.h>
42 #include <sys/stat.h>
43 #include <ufs/ufs/ufsmount.h>
44 #include <err.h>
45 #include <errno.h>
46 #include <fcntl.h>
47 #include <grp.h>
48 #include <limits.h>
49 #include <mntopts.h>
50 #include <stdio.h>
51 #include <stdlib.h>
52 #include <string.h>
53 #include <sysexits.h>
54 #include <unistd.h>
55
56 static void
usage(void)57 usage(void)
58 {
59
60 errx(EX_USAGE, "usage: mksnap_ffs snapshot_name");
61 }
62
63 static int
isdir(const char * path,struct stat * stbufp)64 isdir(const char *path, struct stat *stbufp)
65 {
66
67 if (stat(path, stbufp) < 0)
68 return (-1);
69 if (!S_ISDIR(stbufp->st_mode))
70 return (0);
71 return (1);
72 }
73
74 static int
issamefs(const char * path,struct statfs * stfsp)75 issamefs(const char *path, struct statfs *stfsp)
76 {
77 struct statfs stfsbuf;
78 struct stat stbuf;
79
80 if (isdir(path, &stbuf) != 1)
81 return (-1);
82 if (statfs(path, &stfsbuf) < 0)
83 return (-1);
84 if (fsidcmp(&stfsbuf.f_fsid, &stfsp->f_fsid) != 0)
85 return (0);
86 return (1);
87 }
88
89 int
main(int argc,char ** argv)90 main(int argc, char **argv)
91 {
92 char errmsg[255], path[PATH_MAX];
93 char *cp, *snapname;
94 struct statfs stfsbuf;
95 struct group *grp;
96 struct stat stbuf;
97 struct iovec *iov;
98 int fd, iovlen;
99
100 if (argc == 2)
101 snapname = argv[1];
102 else if (argc == 3)
103 snapname = argv[2]; /* Old usage. */
104 else
105 usage();
106
107 /*
108 * Check that the user running this program has permission
109 * to create and remove a snapshot file from the directory
110 * in which they have requested to have it made. If the
111 * directory is sticky and not owned by the user, then they
112 * will not be able to remove the snapshot when they are
113 * done with it.
114 */
115 if (strlen(snapname) >= PATH_MAX)
116 errx(1, "pathname too long %s", snapname);
117 cp = strrchr(snapname, '/');
118 if (cp == NULL) {
119 strlcpy(path, ".", PATH_MAX);
120 } else if (cp == snapname) {
121 strlcpy(path, "/", PATH_MAX);
122 } else {
123 strlcpy(path, snapname, cp - snapname + 1);
124 }
125 if (statfs(path, &stfsbuf) < 0)
126 err(1, "%s", path);
127 switch (isdir(path, &stbuf)) {
128 case -1:
129 err(1, "%s", path);
130 case 0:
131 errx(1, "%s: Not a directory", path);
132 default:
133 break;
134 }
135 if (access(path, W_OK) < 0)
136 err(1, "Lack write permission in %s", path);
137 if ((stbuf.st_mode & S_ISTXT) && stbuf.st_uid != getuid())
138 errx(1, "Lack write permission in %s: Sticky bit set", path);
139
140 /*
141 * Work around an issue when mksnap_ffs is started in chroot'ed
142 * environment and f_mntonname contains absolute path within
143 * real root.
144 */
145 for (cp = stfsbuf.f_mntonname; issamefs(cp, &stfsbuf) != 1;
146 cp = strchrnul(cp + 1, '/')) {
147 if (cp[0] == '\0')
148 errx(1, "%s: Not a mount point", stfsbuf.f_mntonname);
149 }
150 if (cp != stfsbuf.f_mntonname)
151 strlcpy(stfsbuf.f_mntonname, cp, sizeof(stfsbuf.f_mntonname));
152
153 /*
154 * Having verified access to the directory in which the
155 * snapshot is to be built, proceed with creating it.
156 */
157 if ((grp = getgrnam("operator")) == NULL)
158 errx(1, "Cannot retrieve operator gid");
159
160 iov = NULL;
161 iovlen = 0;
162 build_iovec(&iov, &iovlen, "fstype", "ffs", 4);
163 build_iovec(&iov, &iovlen, "from", snapname, (size_t)-1);
164 build_iovec(&iov, &iovlen, "fspath", stfsbuf.f_mntonname, (size_t)-1);
165 build_iovec(&iov, &iovlen, "errmsg", errmsg, sizeof(errmsg));
166 build_iovec(&iov, &iovlen, "update", NULL, 0);
167 build_iovec(&iov, &iovlen, "snapshot", NULL, 0);
168
169 *errmsg = '\0';
170 if (nmount(iov, iovlen, stfsbuf.f_flags) < 0) {
171 errmsg[sizeof(errmsg) - 1] = '\0';
172 err(1, "Cannot create snapshot %s%s%s", snapname,
173 *errmsg != '\0' ? ": " : "", errmsg);
174 }
175 if ((fd = open(snapname, O_RDONLY)) < 0)
176 err(1, "Cannot open %s", snapname);
177 if (fstat(fd, &stbuf) != 0)
178 err(1, "Cannot stat %s", snapname);
179 if ((stbuf.st_flags & SF_SNAPSHOT) == 0)
180 errx(1, "File %s is not a snapshot", snapname);
181 if (fchown(fd, -1, grp->gr_gid) != 0)
182 err(1, "Cannot chown %s", snapname);
183 if (fchmod(fd, S_IRUSR | S_IRGRP) != 0)
184 err(1, "Cannot chmod %s", snapname);
185
186 exit(EXIT_SUCCESS);
187 }
188