usr/src/sbin/mount_umap/mount_umap.c

/*
 * 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.
 *
 * %sccs.include.redist.c%
 */

#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) %G%";
#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);
}