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 * $FreeBSD$
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
56static void
57usage(void)
58{
59
60	errx(EX_USAGE, "usage: mksnap_ffs snapshot_name");
61}
62
63static int
64isdir(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
74static int
75issamefs(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
89int
90main(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