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authorrgrimes <rgrimes@FreeBSD.org>1994-05-26 06:35:07 +0000
committerrgrimes <rgrimes@FreeBSD.org>1994-05-26 06:35:07 +0000
commitcfcc93eec947df1e540a41375912a5fa84ce75c3 (patch)
tree8575a324f257e2c8533986c80d3418e337a3ff68 /sbin/mount_umapfs
parentf185bf7f09d364269a9c6dcee37a105241cf240f (diff)
downloadFreeBSD-src-cfcc93eec947df1e540a41375912a5fa84ce75c3.zip
FreeBSD-src-cfcc93eec947df1e540a41375912a5fa84ce75c3.tar.gz
BSD 4.4 Lite sbin Sources
Note: XNSrouted and routed NOT imported here, they shall be imported with usr.sbin.
Diffstat (limited to 'sbin/mount_umapfs')
-rw-r--r--sbin/mount_umapfs/Makefile11
-rw-r--r--sbin/mount_umapfs/mount_umapfs.8131
-rw-r--r--sbin/mount_umapfs/mount_umapfs.c232
-rw-r--r--sbin/mount_umapfs/umap_manual175
4 files changed, 549 insertions, 0 deletions
diff --git a/sbin/mount_umapfs/Makefile b/sbin/mount_umapfs/Makefile
new file mode 100644
index 0000000..af1bf2f
--- /dev/null
+++ b/sbin/mount_umapfs/Makefile
@@ -0,0 +1,11 @@
+# @(#)Makefile 8.3 (Berkeley) 3/27/94
+
+PROG= mount_umap
+SRCS= mount_umap.c getmntopts.c
+MAN8= mount_umap.0
+
+MOUNT= ${.CURDIR}/../mount
+CFLAGS+= -I/sys -I${MOUNT}
+.PATH: ${MOUNT}
+
+.include <bsd.prog.mk>
diff --git a/sbin/mount_umapfs/mount_umapfs.8 b/sbin/mount_umapfs/mount_umapfs.8
new file mode 100644
index 0000000..e90ce26
--- /dev/null
+++ b/sbin/mount_umapfs/mount_umapfs.8
@@ -0,0 +1,131 @@
+.\" Copyright (c) 1992, 1993, 1994
+.\" The Regents of the University of California. All rights reserved.
+.\" All rights reserved.
+.\"
+.\" This code is derived from software donated to Berkeley by
+.\" Jan-Simon Pendry and from John Heidemann of the UCLA Ficus project.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\" notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\" notice, this list of conditions and the following disclaimer in the
+.\" documentation and/or other materials provided with the distribution.
+.\" 3. All advertising materials mentioning features or use of this software
+.\" must display the following acknowledgement:
+.\" This product includes software developed by the University of
+.\" California, Berkeley and its contributors.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\" may be used to endorse or promote products derived from this software
+.\" without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" @(#)mount_umap.8 8.3 (Berkeley) 3/27/94
+.\"
+.Dd "March 27, 1994"
+.Dt MOUNT_UMAP 8
+.Os BSD 4.4
+.Sh NAME
+.Nm mount_umap
+.Nd sample file system layer
+.Sh SYNOPSIS
+.Nm mount_umap
+.Op Fl o Ar options
+.Ar target
+.Ar mount-point
+.Ar uid-mapfile
+.Ar gid-mapfile
+.Sh DESCRIPTION
+The
+.Nm mount_umap
+command is used to mount a sub-tree of an existing file system
+that uses a different set of uids and gids than the local system.
+Such a file system could be mounted from a remote site via NFS or
+it could be a file system on removable media brought from some
+foreign location that uses a different password file.
+.Pp
+The options are as follows:
+.Bl -tag -width indent
+.It Fl o
+Options are specified with a
+.Fl o
+flag followed by a comma separated string of options.
+See the
+.Xr mount 8
+man page for possible options and their meanings.
+.El
+.Pp
+The
+.Nm mount_umap
+command uses a set of files provided by the user to make correspondences
+between uids and gids in the sub-tree's original environment and
+some other set of ids in the local environment. For instance, user
+smith might have uid 1000 in the original environment, while having
+uid 2000 in the local environment. The
+.Nm mount_umap
+command allows the subtree from smith's original environment to be
+mapped in such a way that all files with owning uid 1000 look like
+they are actually owned by uid 2000.
+.Pp
+.Em target
+should be the current location of the sub-tree in the
+local system's name space.
+.Em mount-point
+should be a directory
+where the mapped subtree is to be placed.
+.Em uid-mapfile
+and
+.Em gid-mapfile
+describe the mappings to be made between identifiers.
+Briefly, the format of these files is a count of the number of
+mappings on the first line, with each subsequent line containing
+a single mapping. Each of these mappings consists of an id from
+the original environment and the corresponding id in the local environment,
+separated by white space.
+.Em uid-mapfile
+should contain all uid
+mappings, and
+.Em gid-mapfile
+should contain all gid mappings.
+Any uids not mapped in
+.Em uid-mapfile
+will be treated as user NOBODY,
+and any gids not mapped in
+.Em gid-mapfile
+will be treated as group
+NULLGROUP. At most 64 uids can be mapped for a given subtree, and
+at most 16 groups can be mapped by a given subtree.
+.Pp
+The mapfiles can be located anywhere in the file hierarchy, but they
+must be owned by root, and they must be writable only by root.
+.Nm mount_umap
+will refuse to map the sub-tree if the ownership or permissions on
+these files are improper. It will also balk if the count of mappings
+in the first line of the map files is not correct.
+.Pp
+The layer created by the
+.Nm mount_umap
+command is meant to serve as a simple example of file system layering.
+It is not meant for production use. The implementation is not very
+sophisticated.
+.Sh SEE ALSO
+.Xr mount 8 ,
+.Xr mount_null 8 ,
+.Xr mount_lofs 8
+.Sh HISTORY
+The
+.Nm mount_umap
+utility first appeared in 4.4BSD.
diff --git a/sbin/mount_umapfs/mount_umapfs.c b/sbin/mount_umapfs/mount_umapfs.c
new file mode 100644
index 0000000..a069fe5
--- /dev/null
+++ b/sbin/mount_umapfs/mount_umapfs.c
@@ -0,0 +1,232 @@
+/*
+ * Copyright (c) 1992, 1993, 1994
+ * The Regents of the University of California. All rights reserved.
+ *
+ * This code is derived from software donated to Berkeley by
+ * Jan-Simon Pendry.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef lint
+char copyright[] =
+"@(#) Copyright (c) 1992, 1993, 1994\n\
+ The Regents of the University of California. All rights reserved.\n";
+#endif /* not lint */
+
+#ifndef lint
+static char sccsid[] = "@(#)mount_umap.c 8.3 (Berkeley) 3/27/94";
+#endif /* not lint */
+
+#include <sys/param.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+
+#include <miscfs/umapfs/umap.h>
+
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "mntopts.h"
+
+#define ROOTUSER 0
+/*
+ * This define controls whether any user but the superuser can own and
+ * write mapfiles. If other users can, system security can be gravely
+ * compromised. If this is not a concern, undefine SECURITY.
+ */
+#define MAPSECURITY 1
+
+/*
+ * This routine provides the user interface to mounting a umap layer.
+ * It takes 4 mandatory parameters. The mandatory arguments are the place
+ * where the next lower level is mounted, the place where the umap layer is to
+ * be mounted, the name of the user mapfile, and the name of the group
+ * mapfile. The routine checks the ownerships and permissions on the
+ * mapfiles, then opens and reads them. Then it calls mount(), which
+ * will, in turn, call the umap version of mount.
+ */
+
+struct mntopt mopts[] = {
+ MOPT_STDOPTS,
+ { NULL }
+};
+
+void usage __P((void));
+
+int
+main(argc, argv)
+ int argc;
+ char *argv[];
+{
+ static char not[] = "; not mounted.";
+ struct stat statbuf;
+ struct umap_args args;
+ FILE *fp, *gfp;
+ u_long gmapdata[GMAPFILEENTRIES][2], mapdata[MAPFILEENTRIES][2];
+ int ch, count, gnentries, mntflags, nentries;
+ char *gmapfile, *mapfile, *source, *target, buf[20];
+
+ mntflags = 0;
+ mapfile = gmapfile = NULL;
+ while ((ch = getopt(argc, argv, "g:o:u:")) != EOF)
+ switch (ch) {
+ case 'g':
+ gmapfile = optarg;
+ break;
+ case 'o':
+ getmntopts(optarg, mopts, &mntflags);
+ break;
+ case 'u':
+ mapfile = optarg;
+ break;
+ case '?':
+ default:
+ usage();
+ }
+ argc -= optind;
+ argv += optind;
+
+ if (argc != 2 || mapfile == NULL || gmapfile == NULL)
+ usage();
+
+ source = argv[0];
+ target = argv[1];
+
+ /* Read in uid mapping data. */
+ if ((fp = fopen(mapfile, "r")) == NULL)
+ err(1, "%s%s", mapfile, not);
+
+#ifdef MAPSECURITY
+ /*
+ * Check that group and other don't have write permissions on
+ * this mapfile, and that the mapfile belongs to root.
+ */
+ if (fstat(fileno(fp), &statbuf))
+ err(1, "%s%s", mapfile, not);
+ if (statbuf.st_mode & S_IWGRP || statbuf.st_mode & S_IWOTH) {
+ strmode(statbuf.st_mode, buf);
+ err(1, "%s: improper write permissions (%s)%s",
+ mapfile, buf, not);
+ }
+ if (statbuf.st_uid != ROOTUSER)
+ errx(1, "%s does not belong to root%s", mapfile, not);
+#endif /* MAPSECURITY */
+
+ if ((fscanf(fp, "%d\n", &nentries)) != 1)
+ errx(1, "%s: nentries not found%s", mapfile, not);
+ if (nentries > MAPFILEENTRIES)
+ errx(1,
+ "maximum number of entries is %d%s", MAPFILEENTRIES, not);
+#if 0
+ (void)printf("reading %d entries\n", nentries);
+#endif
+ for (count = 0; count < nentries; ++count) {
+ if ((fscanf(fp, "%lu %lu\n",
+ &(mapdata[count][0]), &(mapdata[count][1]))) != 2) {
+ if (ferror(fp))
+ err(1, "%s%s", mapfile, not);
+ if (feof(fp))
+ errx(1, "%s: unexpected end-of-file%s",
+ mapfile, not);
+ errx(1, "%s: illegal format (line %d)%s",
+ mapfile, count + 2, not);
+ }
+#if 0
+ /* Fix a security hole. */
+ if (mapdata[count][1] == 0)
+ errx(1, "mapping id 0 not permitted (line %d)%s",
+ count + 2, not);
+#endif
+ }
+
+ /* Read in gid mapping data. */
+ if ((gfp = fopen(gmapfile, "r")) == NULL)
+ err(1, "%s%s", gmapfile, not);
+
+#ifdef MAPSECURITY
+ /*
+ * Check that group and other don't have write permissions on
+ * this group mapfile, and that the file belongs to root.
+ */
+ if (fstat(fileno(gfp), &statbuf))
+ err(1, "%s%s", gmapfile, not);
+ if (statbuf.st_mode & S_IWGRP || statbuf.st_mode & S_IWOTH) {
+ strmode(statbuf.st_mode, buf);
+ err(1, "%s: improper write permissions (%s)%s",
+ gmapfile, buf, not);
+ }
+ if (statbuf.st_uid != ROOTUSER)
+ errx(1, "%s does not belong to root%s", gmapfile, not);
+#endif /* MAPSECURITY */
+
+ if ((fscanf(fp, "%d\n", &gnentries)) != 1)
+ errx(1, "nentries not found%s", gmapfile, not);
+ if (gnentries > MAPFILEENTRIES)
+ errx(1,
+ "maximum number of entries is %d%s", GMAPFILEENTRIES, not);
+#if 0
+ (void)printf("reading %d group entries\n", gnentries);
+#endif
+
+ for (count = 0; count < gnentries; ++count)
+ if ((fscanf(fp, "%lu %lu\n",
+ &(gmapdata[count][0]), &(gmapdata[count][1]))) != 2) {
+ if (ferror(fp))
+ err(1, "%s%s", gmapfile, not);
+ if (feof(fp))
+ errx(1, "%s: unexpected end-of-file%s",
+ gmapfile, not);
+ errx(1, "%s: illegal format (line %d)%s",
+ gmapfile, count + 2, not);
+ }
+
+
+ /* Setup mount call args. */
+ args.target = source;
+ args.nentries = nentries;
+ args.mapdata = mapdata;
+ args.gnentries = gnentries;
+ args.gmapdata = gmapdata;
+
+ if (mount(MOUNT_UMAP, argv[1], mntflags, &args))
+ err(1, NULL);
+ exit(0);
+}
+
+void
+usage()
+{
+ (void)fprintf(stderr,
+"usage: mount_umap [-o options] -u usermap -g groupmap target_fs mount_point\n");
+ exit(1);
+}
diff --git a/sbin/mount_umapfs/umap_manual b/sbin/mount_umapfs/umap_manual
new file mode 100644
index 0000000..059939f
--- /dev/null
+++ b/sbin/mount_umapfs/umap_manual
@@ -0,0 +1,175 @@
+
+\appendix
+\section{The umap Layer} \label{sect:umap}
+
+\subsection{Introduction}
+
+Normally, the file system is expected to span a single administrative domain.
+An administrative domain, for these purposes, is a machine or set of
+machines that share common password file information, usually through
+the yellow pages mechanism. File hierarchies that span more
+than one domain leads to certain problems, since the same numerical
+UID in one domain may correspond to a different user in another domain.
+If the system administrator is very careful to ensure that both domains
+contain identical user ID information, The umap layer can be used to
+run between those domains without changes
+
+The umap layer is a file system layer that sits on top of the normal
+file layer. The umap layer maps Unix-style UIDs from
+one domain into the UIDs in the other domain. By setting up the mappings
+properly, the same user with different UIDs in two domains can be seen
+as the same user, from the system point of view, or, conversely, two
+different users with the same UID in the two domains can be distinguished.
+
+First, we define some terms. ``User'' refers to the human (or daemon) that
+has privileges to login, run programs, and access files. ``UID''refers to
+the numerical identifier that uniquely identifies the user within a
+single domain. ``Login name'' refers to the character string the user
+types to log into the system. ``GID'' refers to the numerical group
+identifier used by Unix systems to identify groups of users. ``Group
+name'' is the character string name attached to a particular GID in the
+local {\sf /etc/groups} file or the yellow pages groups file.
+
+In order for the umap layer to work properly, all users
+in either domain must have password file entries in both domains.
+They do not, however, have to have the same numerical UID, nor even the
+same character string login name (the latter is highly recommended,
+if possible, however). Any user not having a UID in one domain will be
+treated as the special user NOBODY by the other domain, probably with
+undesirable consequences. Any user not owning any files in the shared
+sub-trees need not be given a UID in the other domain.
+
+Groups work similarly. The umap layer can translate group ID's between
+domains in the same manner as UID's. Again, any group that wishes to
+participate must have a group ID in both domains,
+though it need not be the same GID in both. If a group in one domain is not
+known in the other domain, that group will be treated as being NULLGROUP.
+The umap layer has no provisions for enrolling UID's from other domains
+as group members, but, since each user from each domain must have some
+UID in every domain, the UID in the local domain can be used to enroll
+the user in the local groups.
+
+NOBODY and NULLGROUP are special reserved UID's and GID's, respectively.
+NOBODY is user 32767. NULLGROUP is group 65534. If the system administrator
+wants to have an appropriate text string appear when these UID's are
+encountered by programs like {\sf ls -l}, he should add these values to
+the password and {\sf /etc/groups} file, or to the appropriate yellow pages.
+If these IDs are already in use in that domain, different values can be
+used for NOBODY and NULLGROUP, but that will require a recompilation of
+the umap layer code and, as a result, the entire kernel. These
+values are defined in the {\sf umap\_info.h} file, kept with the rest of the
+umap source code.
+
+When the umap layer is in use, one of the participating domains is declared
+to be the master. All UID and GID information stored for participating files
+will be stored in vnodes using its mappings, no matter what site the copies of
+the files are stored at. The master domain therefore need not run a copy
+of the umap layer, as it already has all of the correct mappings. All
+other domains must run a umap layer on top of any other layers they use.
+
+\subsection{Setting Up a umap Layer}
+
+The system administrator of a system needing to use the umap layer
+must take several actions.
+First, he must create files containing the necessary UID
+and GID mappings. There is a separate file for user and group IDs. The
+format of the files is the same. The first line contains the total number
+of entries in the file. Each subsequent line contains one mapping. A
+mapping line consists of two numerical UIDs, separated by white space.
+The first is the UID of a user on the local machine. The second is the
+UID for the same user on the master machine. The maximum number of users
+that can be mapped for a single shared sub-tree is 64. The maximum number of
+groups that can be mapped for a single sub-tree is 16. These constants
+are set in the {\sf umap\_info.h} file, and can be changed, but changing them
+requires recompilation. Separate mapping files can be used for each shared
+subtree, or the same mapping files can be shared by several sub-trees.
+
+Below is a sample UID mapping file. There are four entries. UID 5 is mapped
+to 5, 521 to 521, and 7000 to 7000. UID 2002 is mapped to 604. On this
+machine, the UID's for users 5, 521, and 7000 are the same as on the master,
+but UID 2002 is for a user whose UID on the master machine is 604. All
+files in the sub-tree belonging to that user have UID 604 in their inodes,
+even on this machine, but the umap layer will ensure that anyone running
+under UID 2002 will have all files in this sub-tree owned by 604 treated as if
+they were owned by 2002. An {\sf ls -l} on a file owned by 604 in this sub-tree
+will show the login name associated with UID 2002 as the owner.
+
+\noindent4\newline
+5 5\newline
+521 521\newline
+2002 604\newline
+7000 7000\newline
+
+The user and group mapping files should be owned by the root user, and
+should be writable only by that user. If they are not owned by root, or
+are writable by some other user, the umap mounting command will abort.
+
+Normally, the sub-treeis grafted directly into the place in
+the file hierarchy where the it should appear to users.Using the umap
+layer requires that the sub-tree be grafted somewhere else, and
+the umap layer be mounted in the desired position in the file hierarchy.
+Depending on the situation, the underlying sub-tree can be wherever is
+convenient.
+
+\subsection{Troubleshooting umap Layer Problems}
+
+The umap layer code was not built with special convenience or
+robustness in mind, as it is expected to be superseded with a better
+user ID mapping strategy in the near future. As a result, it is not
+very forgiving of errors in being set up. Here are some possible
+problems, and what to do about them.
+
+\begin{itemize}
+
+
+\item{Problem: A file belongs to NOBODY, or group NULLGROUP.
+
+Fixes: The mapping files don't know about this file's real user or group.
+Either they are not in the mapping files, or the counts on the number of
+entries in the mapping files are too low, so entries at the end (including
+these) are being ignored. Add the entries or fix the counts, and either
+unmount and remount the sub-tree, or reboot.}
+
+\item{Problem: A normal operation does not work.
+
+Fixes: Possibly, some mapping has not been set properly. Check to
+see which files are used by the operation and who they appear to be
+owned by. If they are owned by NOBODY or some other suspicious user,
+there may be a problem in the mapping files. Be sure to check groups,
+too. As above, if the counts of mappings in the mapping files are lower
+than the actual numbers of pairs, pairs at the end of the file will be
+ignored. If any changes are made in the mapping files, you will need to
+either unmount and remount or reboot before they will take effect.
+
+Another possible problem can arise because not all Unix utilities
+rely exclusively on numeric UID for identification. For instance,
+SCCS saves the login name in files. If a user's login name on two machines
+isn't the same, SCCS may veto an operation even though Unix file permissions,
+as checked by the umap layer, may say it's OK. There's not much to be
+done in such cases, unless the login name can be changed or one fiddles
+improperly with SCCS information. There may be other, undiscovered cases
+where similar problems arise, some of which may be even harder to handle.}
+
+\item{Problem: Someone has access permissions he should not have.
+
+Fixes: This is probably caused by a mistake in the mapping files. Check
+both user and group mapping files. If any changes are made in the mapping
+files, you will need to unmount and remount the sub-tree or reboot before they
+will take effect.}
+
+\item{Problem: {\sf ls -l} (or a similar program) shows the wrong user for a file.
+
+Fixes: Probably a mistake in the mapping files. In particular, if
+two local UIDs are mapped to a single master UID, stat calls will assign
+ownership to the first local UID occurring in the file, which may or may
+not be what was intended. (Generally speaking, mapping two local UIDs to
+a single master UID is a bad idea, but the software will not prevent it.
+Similarly, mapping a single local UID to two master UIDs is a bad idea,
+but will not be prevented. In this case, only the first mapping of the
+local UID will be done. The second, and all subsequent ones, will be
+ignored.) If any changes are made in the mapping files, you will need to
+unmount and remount the sub-tree or reboot before they will take effect.}
+
+\end{itemize}
+
+\end{document}
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