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