591e89c89b
The problem is that the statfs(2) system call used to determine the relevant mount point returns path within real root in the f_mntonname, causing nmount(2) system call to fail with ENOENT. Use a bit of heuristics to skip over few starting path elements when it happens until we hit an actual mount point. For this to work properly the whole mount should be accessible within the chroot, it's going to still fail if chroot only has access to a part of the mounted fs. Reviewed by: mckusick Approved by: mckusick MFC after: 2 weeks
187 lines
5.5 KiB
C
187 lines
5.5 KiB
C
/*
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* Copyright (c) 2003 Networks Associates Technology, Inc.
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* All rights reserved.
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*
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* This software was developed for the FreeBSD Project by Marshall
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* Kirk McKusick and Network Associates Laboratories, the Security
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* Research Division of Network Associates, Inc. under DARPA/SPAWAR
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* contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS
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* research program.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The names of the authors may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/param.h>
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#include <sys/mount.h>
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#include <sys/stat.h>
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#include <ufs/ufs/ufsmount.h>
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <grp.h>
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#include <limits.h>
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#include <mntopts.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sysexits.h>
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#include <unistd.h>
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static void
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usage(void)
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{
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errx(EX_USAGE, "usage: mksnap_ffs snapshot_name");
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}
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static int
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isdir(const char *path)
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{
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struct stat stbuf;
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if (stat(path, &stbuf) < 0)
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return (-1);
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if (!S_ISDIR(stbuf.st_mode))
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return (0);
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return (1);
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}
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static int
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issamefs(const char *path, struct statfs *stfsp)
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{
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struct statfs stfsbuf;
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if (isdir(path) != 1)
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return (-1);
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if (statfs(path, &stfsbuf) < 0)
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return (-1);
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if ((stfsbuf.f_fsid.val[0] != stfsp->f_fsid.val[0]) ||
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(stfsbuf.f_fsid.val[1] != stfsp->f_fsid.val[1]))
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return (0);
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return (1);
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}
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int
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main(int argc, char **argv)
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{
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char errmsg[255], path[PATH_MAX];
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char *cp, *snapname;
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struct statfs stfsbuf;
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struct group *grp;
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struct stat stbuf;
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struct iovec *iov;
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int fd, iovlen;
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if (argc == 2)
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snapname = argv[1];
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else if (argc == 3)
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snapname = argv[2]; /* Old usage. */
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else
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usage();
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/*
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* Check that the user running this program has permission
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* to create and remove a snapshot file from the directory
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* in which they have requested to have it made. If the
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* directory is sticky and not owned by the user, then they
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* will not be able to remove the snapshot when they are
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* done with it.
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*/
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if (strlen(snapname) >= PATH_MAX)
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errx(1, "pathname too long %s", snapname);
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cp = strrchr(snapname, '/');
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if (cp == NULL) {
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strlcpy(path, ".", PATH_MAX);
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} else if (cp == snapname) {
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strlcpy(path, "/", PATH_MAX);
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} else {
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strlcpy(path, snapname, cp - snapname + 1);
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}
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if (statfs(path, &stfsbuf) < 0)
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err(1, "%s", path);
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switch (isdir(path)) {
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case -1:
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err(1, "%s", path);
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case 0:
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errx(1, "%s: Not a directory", path);
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default:
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break;
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}
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if (access(path, W_OK) < 0)
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err(1, "Lack write permission in %s", path);
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if ((stbuf.st_mode & S_ISTXT) && stbuf.st_uid != getuid())
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errx(1, "Lack write permission in %s: Sticky bit set", path);
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/*
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* Work around an issue when mksnap_ffs is started in chroot'ed
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* environment and f_mntonname contains absolute path within
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* real root.
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*/
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for (cp = stfsbuf.f_mntonname; issamefs(cp, &stfsbuf) != 1;
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cp = strchrnul(cp + 1, '/')) {
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if (cp[0] == '\0')
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errx(1, "%s: Not a mount point", stfsbuf.f_mntonname);
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}
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if (cp != stfsbuf.f_mntonname)
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strlcpy(stfsbuf.f_mntonname, cp, sizeof(stfsbuf.f_mntonname));
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/*
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* Having verified access to the directory in which the
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* snapshot is to be built, proceed with creating it.
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*/
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if ((grp = getgrnam("operator")) == NULL)
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errx(1, "Cannot retrieve operator gid");
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iov = NULL;
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iovlen = 0;
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build_iovec(&iov, &iovlen, "fstype", "ffs", 4);
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build_iovec(&iov, &iovlen, "from", snapname, (size_t)-1);
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build_iovec(&iov, &iovlen, "fspath", stfsbuf.f_mntonname, (size_t)-1);
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build_iovec(&iov, &iovlen, "errmsg", errmsg, sizeof(errmsg));
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build_iovec(&iov, &iovlen, "update", NULL, 0);
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build_iovec(&iov, &iovlen, "snapshot", NULL, 0);
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*errmsg = '\0';
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if (nmount(iov, iovlen, stfsbuf.f_flags) < 0) {
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errmsg[sizeof(errmsg) - 1] = '\0';
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err(1, "Cannot create snapshot %s%s%s", snapname,
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*errmsg != '\0' ? ": " : "", errmsg);
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}
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if ((fd = open(snapname, O_RDONLY)) < 0)
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err(1, "Cannot open %s", snapname);
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if (fstat(fd, &stbuf) != 0)
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err(1, "Cannot stat %s", snapname);
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if ((stbuf.st_flags & SF_SNAPSHOT) == 0)
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errx(1, "File %s is not a snapshot", snapname);
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if (fchown(fd, -1, grp->gr_gid) != 0)
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err(1, "Cannot chown %s", snapname);
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if (fchmod(fd, S_IRUSR | S_IRGRP) != 0)
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err(1, "Cannot chmod %s", snapname);
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exit(EXIT_SUCCESS);
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}
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