nfs/umount/umount.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * nfs umount
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <signal.h>
#include <unistd.h>
#include <kstat.h>
#include <rpc/rpc.h>
#include <sys/mnttab.h>
#include <sys/mount.h>
#include <sys/mntent.h>
#include <nfs/nfs.h>
#include <nfs/nfs_clnt.h>
#include <rpcsvc/mount.h>
#include <errno.h>
#include <locale.h>
#include <fslib.h>
#include <priv.h>
#include <tsol/label.h>
#include "replica.h"

#define RET_OK  0
#define RET_ERR 32

#ifdef __STDC__
static void pr_err(const char *fmt, ...);
#else
static void pr_err(char *fmt, va_dcl);
#endif
static  void    usage();
static  int nfs_unmount(char *, int);
static  void    inform_server(char *, char *, bool_t);
static  struct extmnttab *mnttab_find();
extern int __clnt_bindresvport(CLIENT *);

static  int is_v4_mount(struct extmnttab *);

static char *myname;
static char typename[64];

int
main(int argc, char *argv[])
{
    extern int optind;
    int c;
    int umnt_flag = 0;

    (void) setlocale(LC_ALL, "");

#if !defined(TEXT_DOMAIN)
#define TEXT_DOMAIN "SYS_TEST"
#endif
    (void) textdomain(TEXT_DOMAIN);

    myname = strrchr(argv[0], '/');
    myname = myname ? myname+1 : argv[0];
    (void) snprintf(typename, sizeof (typename), "nfs %s", myname);
    argv[0] = typename;

    /*
     * Set options
     */
    while ((c = getopt(argc, argv, "f")) != EOF) {
        switch (c) {
        case 'f':
            umnt_flag |= MS_FORCE; /* forced unmount is desired */
            break;
        default:
            usage();
            exit(RET_ERR);
        }
    }
    if (argc - optind != 1) {
        usage();
        exit(RET_ERR);
    }

    if (!priv_ineffect(PRIV_SYS_MOUNT) ||
        !priv_ineffect(PRIV_NET_PRIVADDR)) {
        pr_err(gettext("insufficient privileges\n"));
        exit(RET_ERR);
    }

    /*
     * On a labeled system, a MAC flag may be needed if the mount is
     * read-down, so attempt to assert it but ignore errors in any case.
     */
    if (is_system_labeled())
        (void) setpflags(NET_MAC_AWARE, 1);

    /*
     * exit, really
     */
    return (nfs_unmount(argv[optind], umnt_flag));
}

static void
pr_err(const char *fmt, ...)
{
    va_list ap;

    va_start(ap, fmt);
    (void) fprintf(stderr, "%s: ", typename);
    (void) vfprintf(stderr, fmt, ap);
    (void) fflush(stderr);
    va_end(ap);
}

static void
usage()
{
    (void) fprintf(stderr,
        gettext("Usage: nfs umount [-f] {server:path | dir}\n"));
    exit(RET_ERR);
}

static int
nfs_unmount(char *pathname, int umnt_flag)
{
    struct extmnttab *mntp;
    bool_t quick = FALSE;
    int is_v4 = FALSE;

    mntp = mnttab_find(pathname);
    if (mntp) {
        pathname = mntp->mnt_mountp;
    }

    if (mntp)
        is_v4 = is_v4_mount(mntp);

    /* Forced unmount will almost always be successful */
    if (umount2(pathname, umnt_flag) < 0) {
        if (errno == EBUSY) {
            pr_err(gettext("%s: is busy\n"), pathname);
        } else {
            pr_err(gettext("%s: not mounted\n"), pathname);
        }
        return (RET_ERR);
    }

    /* All done if it's v4 */
    if (is_v4 == TRUE)
        return (RET_OK);

    /* Inform server quickly in case of forced unmount */
    if (umnt_flag & MS_FORCE)
        quick = TRUE;

    if (mntp) {
        inform_server(mntp->mnt_special, mntp->mnt_mntopts, quick);
    }

    return (RET_OK);
}

/*
 *  Find the mnttab entry that corresponds to "name".
 *  We're not sure what the name represents: either
 *  a mountpoint name, or a special name (server:/path).
 *  Return the last entry in the file that matches.
 */
static struct extmnttab *
mnttab_find(dirname)
    char *dirname;
{
    FILE *fp;
    struct extmnttab mnt;
    struct extmnttab *res = NULL;

    fp = fopen(MNTTAB, "r");
    if (fp == NULL) {
        pr_err("%s: %s\n", MNTTAB, strerror(errno));
        return (NULL);
    }
    while (getextmntent(fp, &mnt, sizeof (struct extmnttab)) == 0) {
        if (strcmp(mnt.mnt_mountp, dirname) == 0 ||
            strcmp(mnt.mnt_special, dirname) == 0) {
            if (res)
                fsfreemnttab(res);
            res = fsdupmnttab(&mnt);
        }
    }

    (void) fclose(fp);
    return (res);
}

/*
 * If quick is TRUE, it will try to inform server quickly
 * as possible.
 */
static void
inform_server(char *string, char *opts, bool_t quick)
{
    struct timeval timeout;
    CLIENT *cl;
    enum clnt_stat rpc_stat;
    struct replica *list;
    int i, n;
    char *p = NULL;
    static struct timeval create_timeout = {5, 0};
    static struct timeval *timep;

    list = parse_replica(string, &n);

    if (list == NULL) {
        if (n < 0)
            pr_err(gettext("%s is not hostname:path format\n"),
                string);
        else
            pr_err(gettext("no memory\n"));
        return;
    }

    /*
     * If mounted with -o public, then no need to contact server
     * because mount protocol was not used.
     */
    if (opts != NULL)
        p = strstr(opts, MNTOPT_PUBLIC);

    if (p != NULL) {
        i = strlen(MNTOPT_PUBLIC);
        /*
         * Now make sure the match of "public" isn't a substring
         * of another option.
         */
        if (((p == opts) || (*(p-1) == ',')) &&
            ((p[i] == ',') || (p[i] == '\0')))
            return;
    }

    for (i = 0; i < n; i++) {
        int vers;

        /*
         * Skip file systems mounted using WebNFS, because mount
         * protocol was not used.
         */
        if (strcmp(list[i].host, "nfs") == 0 && strncmp(list[i].path,
            "//", 2) == 0)
            continue;

        vers =  MOUNTVERS;
retry:
        /*
         * Use 5 sec. timeout if file system is forced unmounted,
         * otherwise use default timeout to create a client handle.
         * This would minimize the time to force unmount a file
         * system reside on a server that is down.
         */
        timep = (quick ? &create_timeout : NULL);
        cl = clnt_create_timed(list[i].host, MOUNTPROG, vers,
            "datagram_n", timep);
        /*
         * Do not print any error messages in case of forced
         * unmount.
         */
        if (cl == NULL) {
            if (!quick)
                pr_err("%s:%s %s\n", list[i].host, list[i].path,
                    clnt_spcreateerror(
                    "server not responding"));
            continue;
        }
        /*
         * Now it is most likely that the NFS client will be able
         * to contact the server since rpcbind is running on
         * the server. There is still a small window in which
         * server can be unreachable.
         */

        if (__clnt_bindresvport(cl) < 0) {
            if (!quick)
                pr_err(gettext(
                    "couldn't bind to reserved port\n"));
            clnt_destroy(cl);
            return;
        }
        if ((cl->cl_auth = authsys_create_default()) == NULL) {
            if (!quick)
                pr_err(gettext(
                    "couldn't create authsys structure\n"));
            clnt_destroy(cl);
            return;
        }
        timeout.tv_usec = 0;
        timeout.tv_sec = 5;
        clnt_control(cl, CLSET_RETRY_TIMEOUT, (char *)&timeout);
        timeout.tv_sec = 25;
        rpc_stat = clnt_call(cl, MOUNTPROC_UMNT, xdr_dirpath,
            (char *)&list[i].path, xdr_void, (char *)NULL,
            timeout);
        AUTH_DESTROY(cl->cl_auth);
        clnt_destroy(cl);
        if (rpc_stat == RPC_PROGVERSMISMATCH && vers == MOUNTVERS) {
            /*
             * The rare case of a v3-only server
             */
            vers = MOUNTVERS3;
            goto retry;
        }
        if (rpc_stat != RPC_SUCCESS)
            pr_err("%s\n", clnt_sperror(cl, "unmount"));
    }

    free_replica(list, n);
}

/*
 * This function's behavior is taken from nfsstat.
 * Trying to determine what NFS version was used for the mount.
 */
int
is_v4_mount(struct extmnttab *mntp)
{
    kstat_ctl_t *kc = NULL;     /* libkstat cookie */
    kstat_t *ksp;
    struct mntinfo_kstat mik;

    if (mntp == NULL)
        return (FALSE);

    if ((kc = kstat_open()) == NULL)
        return (FALSE);

    for (ksp = kc->kc_chain; ksp; ksp = ksp->ks_next) {
        if (ksp->ks_type != KSTAT_TYPE_RAW)
            continue;
        if (strcmp(ksp->ks_module, "nfs") != 0)
            continue;
        if (strcmp(ksp->ks_name, "mntinfo") != 0)
            continue;
        if (mntp->mnt_minor != ksp->ks_instance)
            continue;

        if (kstat_read(kc, ksp, &mik) == -1)
            continue;

        if (mik.mik_vers == 4)
            return (TRUE);
        else
            return (FALSE);
    }
    return (FALSE);
}