mksnap_ffs.c revision 125107 
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: head/sbin/mksnap_ffs/mksnap_ffs.c 125107 2004-01-27 19:28:13Z des $
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 <stdio.h>
48#include <stdlib.h>
49#include <string.h>
50#include <sysexits.h>
51#include <unistd.h>
52
53void usage(void);
54
55int
56main(int argc, char **argv)
57{
58	char *dir, *cp, path[PATH_MAX];
59	struct statfs stfsbuf;
60	struct ufs_args args;
61	struct group *grp;
62	struct stat stbuf;
63	int fd;
64
65	if (argc != 3)
66		usage();
67
68	dir = argv[1];
69	args.fspec = argv[2];
70
71	/*
72	 * Check that the user running this program has permission
73	 * to create and remove a snapshot file from the directory
74	 * in which they have requested to have it made. If the
75	 * directory is sticky and not owned by the user, then they
76	 * will not be able to remove the snapshot when they are
77	 * done with it.
78	 */
79	if (strlen(args.fspec) >= PATH_MAX)
80		errx(1, "pathname too long %s", args.fspec);
81	cp = strrchr(args.fspec, '/');
82	if (cp == NULL) {
83		strlcpy(path, ".", PATH_MAX);
84	} else if (cp == args.fspec) {
85		strlcpy(path, "/", PATH_MAX);
86	} else {
87		strlcpy(path, args.fspec, cp - args.fspec + 1);
88	}
89	if (statfs(path, &stfsbuf) < 0)
90		err(1, "%s", path);
91	if (stat(path, &stbuf) < 0)
92		err(1, "%s", path);
93	if (!S_ISDIR(stbuf.st_mode))
94		errx(1, "%s: Not a directory", path);
95	if (access(path, W_OK) < 0)
96		err(1, "Lack write permission in %s", path);
97	if ((stbuf.st_mode & S_ISTXT) && stbuf.st_uid != getuid())
98		errx(1, "Lack write permission in %s: Sticky bit set", path);
99
100	/*
101	 * Having verified access to the directory in which the
102	 * snapshot is to be built, proceed with creating it.
103	 */
104	if ((grp = getgrnam("operator")) == NULL)
105		errx(1, "Cannot retrieve operator gid");
106	if (mount("ffs", dir, MNT_UPDATE | MNT_SNAPSHOT | stfsbuf.f_flags,
107	    &args) < 0)
108		err(1, "Cannot create %s", args.fspec);
109	if ((fd = open(args.fspec, O_RDONLY)) < 0)
110		err(1, "Cannot open %s", args.fspec);
111	if (fstat(fd, &stbuf) != 0)
112		err(1, "Cannot stat %s", args.fspec);
113	if ((stbuf.st_flags & SF_SNAPSHOT) == 0)
114		errx(1, "File %s is not a snapshot", args.fspec);
115	if (fchown(fd, -1, grp->gr_gid) != 0)
116		err(1, "Cannot chown %s", args.fspec);
117	if (fchmod(fd, S_IRUSR | S_IRGRP) != 0)
118		err(1, "Cannot chmod %s", args.fspec);
119
120	exit(EXIT_SUCCESS);
121}
122
123void
124usage()
125{
126
127	fprintf(stderr, "usage: mksnap_ffs mountpoint snapshot_name\n");
128	exit(EX_USAGE);
129}
130