/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
 *
 * 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. Berkeley Software Design Inc's name may not be used to endorse or
 *    promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``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 BERKELEY SOFTWARE DESIGN INC 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.
 *
 *      from BSDI kern.c,v 1.2 1998/11/25 22:38:27 don Exp
 */

#include <sys/param.h>
#include <sys/mount.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/stat.h>

#include <netinet/in.h>
#include <arpa/inet.h>

#include <assert.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <netdb.h>

#include "nlm_prot.h"
#include <nfs/nfsproto.h>
#include <nfs/nfs_lock.h>

#include "lockd.h"
#include "lockd_lock.h"
#include <nfsclient/nfs.h>

#define DAEMON_USERNAME "daemon"

/* Lock request owner. */
typedef struct __owner {
        pid_t    pid;                           /* Process ID. */
        time_t   tod;                           /* Time-of-day. */
} OWNER;
static OWNER owner;

static char hostname[MAXHOSTNAMELEN + 1];       /* Hostname. */
static int devfd;

static void     client_cleanup(void);
static const char *from_addr(struct sockaddr *);
int     lock_request(LOCKD_MSG *);
static void     set_auth(CLIENT *cl, struct xucred *ucred);
void    show(LOCKD_MSG *);
int     test_request(LOCKD_MSG *);
int     unlock_request(LOCKD_MSG *);

static int
nfslockdans(int vers, struct lockd_ans *ansp)
{

        ansp->la_vers = vers;
        return (write(devfd, ansp, sizeof *ansp) <= 0);
}

/*
 * will break because fifo needs to be repopened when EOF'd
 */
#define lockd_seteuid(uid)      seteuid(uid)

#define d_calls (debug_level > 1)
#define d_args (debug_level > 2)

static const char *
from_addr(struct sockaddr *saddr)
{
        static char inet_buf[INET6_ADDRSTRLEN];

        if (getnameinfo(saddr, saddr->sa_len, inet_buf, sizeof(inet_buf),
                        NULL, 0, NI_NUMERICHOST) == 0)
                return inet_buf;
        return "???";
}

void
client_cleanup(void)
{
        (void)lockd_seteuid(0);
        exit(-1);
}

/*
 * client_request --
 *      Loop around messages from the kernel, forwarding them off to
 *      NLM servers.
 */
pid_t
client_request(void)
{
        LOCKD_MSG msg;
        int nr, ret;
        pid_t child;
        uid_t daemon_uid;
        struct passwd *pw;

        /* Open the dev . */
        devfd = open(_PATH_DEV _PATH_NFSLCKDEV, O_RDWR | O_NONBLOCK);
        if (devfd < 0) {
                syslog(LOG_ERR, "open: %s: %m", _PATH_NFSLCKDEV);
                goto err;
        }

        signal(SIGPIPE, SIG_IGN);

        /*
         * Create a separate process, the client code is really a separate
         * daemon that shares a lot of code.
         */
        switch (child = fork()) {
        case -1:
                err(1, "fork");
        case 0:
                setproctitle("client");
                break;
        default:
                setproctitle("server");
                return (child);
        }

        signal(SIGHUP, (sig_t)client_cleanup);
        signal(SIGTERM, (sig_t)client_cleanup);

        /* Setup. */
        (void)time(&owner.tod);
        owner.pid = getpid();
        (void)gethostname(hostname, sizeof(hostname) - 1);

        pw = getpwnam(DAEMON_USERNAME);
        if (pw == NULL) {
                syslog(LOG_ERR, "getpwnam: %s: %m", DAEMON_USERNAME);
                goto err;
        }
        daemon_uid = pw->pw_uid;
        /* drop our root privileges */
        (void)lockd_seteuid(daemon_uid);

        for (;;) {
                /* Read the fixed length message. */
                if ((nr = read(devfd, &msg, sizeof(msg))) == sizeof(msg)) {
                        if (d_args)
                                show(&msg);

                        if (msg.lm_version != LOCKD_MSG_VERSION) {
                                syslog(LOG_ERR,
                                    "unknown msg type: %d", msg.lm_version);
                        }
                        /*
                         * Send it to the NLM server and don't grant the lock
                         * if we fail for any reason.
                         */
                        switch (msg.lm_fl.l_type) {
                        case F_RDLCK:
                        case F_WRLCK:
                                if (msg.lm_getlk)
                                        ret = test_request(&msg);
                                else
                                        ret = lock_request(&msg);
                                break;
                        case F_UNLCK:
                                ret = unlock_request(&msg);
                                break;
                        default:
                                ret = 1;
                                syslog(LOG_ERR,
                                    "unknown lock type: %d", msg.lm_fl.l_type);
                                break;
                        }
                        if (ret) {
                                struct lockd_ans ans;

                                ans.la_msg_ident = msg.lm_msg_ident;
                                ans.la_errno = EHOSTUNREACH;

                                if (nfslockdans(LOCKD_ANS_VERSION, &ans)) {
                                        syslog((errno == EPIPE ? LOG_INFO : 
                                                LOG_ERR), "process %lu: %m",
                                                (u_long)msg.lm_msg_ident.pid);
                                }
                        }
                } else if (nr == -1) {
                        if (errno != EAGAIN) {
                                syslog(LOG_ERR, "read: %s: %m", _PATH_NFSLCKDEV);
                                goto err;
                        }
                } else if (nr != 0) {
                        syslog(LOG_ERR,
                            "%s: discard %d bytes", _PATH_NFSLCKDEV, nr);
                }
        }

        /* Reached only on error. */
err:
        (void)lockd_seteuid(0);
        _exit (1);
}

void
set_auth(CLIENT *cl, struct xucred *xucred)
{
        int ngroups;
        gid_t *groups;

        /*
         * Exclude the first element if it is actually the egid, but account for
         * the possibility that we could eventually exclude the egid from the
         * exported group list some day.
         */
        ngroups = xucred->cr_ngroups;
        groups = &xucred->cr_groups[0];
        if (groups == &xucred->cr_gid) {
                assert(ngroups > 0);
                ngroups--;
                groups++;
        }
        if (ngroups > NGRPS)
                ngroups = NGRPS;
        if (cl->cl_auth != NULL)
                cl->cl_auth->ah_ops->ah_destroy(cl->cl_auth);
        cl->cl_auth = authunix_create(hostname,
                        xucred->cr_uid,
                        xucred->cr_gid,
                        ngroups,
                        groups);
}


/*
 * test_request --
 *      Convert a lock LOCKD_MSG into an NLM request, and send it off.
 */
int
test_request(LOCKD_MSG *msg)
{
        CLIENT *cli;
        struct timeval timeout = {0, 0};        /* No timeout, no response. */
        char dummy;

        if (d_calls)
                syslog(LOG_DEBUG, "test request: %s: %s to %s",
                    msg->lm_nfsv3 ? "V4" : "V1/3",
                    msg->lm_fl.l_type == F_WRLCK ? "write" : "read",
                    from_addr((struct sockaddr *)&msg->lm_addr));

        if (msg->lm_nfsv3) {
                struct nlm4_testargs arg4;

                arg4.cookie.n_bytes = (char *)&msg->lm_msg_ident;
                arg4.cookie.n_len = sizeof(msg->lm_msg_ident);
                arg4.exclusive = msg->lm_fl.l_type == F_WRLCK ? 1 : 0;
                arg4.alock.caller_name = hostname;
                arg4.alock.fh.n_bytes = (char *)&msg->lm_fh;
                arg4.alock.fh.n_len = msg->lm_fh_len;
                arg4.alock.oh.n_bytes = (char *)&owner;
                arg4.alock.oh.n_len = sizeof(owner);
                arg4.alock.svid = msg->lm_msg_ident.pid;
                arg4.alock.l_offset = msg->lm_fl.l_start;
                arg4.alock.l_len = msg->lm_fl.l_len;

                if ((cli = get_client(
                    (struct sockaddr *)&msg->lm_addr,
                    NLM_VERS4)) == NULL)
                        return (1);

                set_auth(cli, &msg->lm_cred);
                (void)clnt_call(cli, NLM_TEST_MSG,
                    (xdrproc_t)xdr_nlm4_testargs, &arg4,
                    (xdrproc_t)xdr_void, &dummy, timeout);
        } else {
                struct nlm_testargs arg;

                arg.cookie.n_bytes = (char *)&msg->lm_msg_ident;
                arg.cookie.n_len = sizeof(msg->lm_msg_ident);
                arg.exclusive = msg->lm_fl.l_type == F_WRLCK ? 1 : 0;
                arg.alock.caller_name = hostname;
                arg.alock.fh.n_bytes = (char *)&msg->lm_fh;
                arg.alock.fh.n_len = msg->lm_fh_len;
                arg.alock.oh.n_bytes = (char *)&owner;
                arg.alock.oh.n_len = sizeof(owner);
                arg.alock.svid = msg->lm_msg_ident.pid;
                arg.alock.l_offset = msg->lm_fl.l_start;
                arg.alock.l_len = msg->lm_fl.l_len;

                if ((cli = get_client(
                    (struct sockaddr *)&msg->lm_addr,
                    NLM_VERS)) == NULL)
                        return (1);

                set_auth(cli, &msg->lm_cred);
                (void)clnt_call(cli, NLM_TEST_MSG,
                    (xdrproc_t)xdr_nlm_testargs, &arg,
                    (xdrproc_t)xdr_void, &dummy, timeout);
        }
        return (0);
}

/*
 * lock_request --
 *      Convert a lock LOCKD_MSG into an NLM request, and send it off.
 */
int
lock_request(LOCKD_MSG *msg)
{
        CLIENT *cli;
        struct nlm4_lockargs arg4;
        struct nlm_lockargs arg;
        struct timeval timeout = {0, 0};        /* No timeout, no response. */
        char dummy;

        if (d_calls)
                syslog(LOG_DEBUG, "lock request: %s: %s to %s",
                    msg->lm_nfsv3 ? "V4" : "V1/3",
                    msg->lm_fl.l_type == F_WRLCK ? "write" : "read",
                    from_addr((struct sockaddr *)&msg->lm_addr));

        if (msg->lm_nfsv3) {
                arg4.cookie.n_bytes = (char *)&msg->lm_msg_ident;
                arg4.cookie.n_len = sizeof(msg->lm_msg_ident);
                arg4.block = msg->lm_wait ? 1 : 0;
                arg4.exclusive = msg->lm_fl.l_type == F_WRLCK ? 1 : 0;
                arg4.alock.caller_name = hostname;
                arg4.alock.fh.n_bytes = (char *)&msg->lm_fh;
                arg4.alock.fh.n_len = msg->lm_fh_len;
                arg4.alock.oh.n_bytes = (char *)&owner;
                arg4.alock.oh.n_len = sizeof(owner);
                arg4.alock.svid = msg->lm_msg_ident.pid;
                arg4.alock.l_offset = msg->lm_fl.l_start;
                arg4.alock.l_len = msg->lm_fl.l_len;
                arg4.reclaim = 0;
                arg4.state = nsm_state;

                if ((cli = get_client(
                    (struct sockaddr *)&msg->lm_addr,
                    NLM_VERS4)) == NULL)
                        return (1);

                set_auth(cli, &msg->lm_cred);
                (void)clnt_call(cli, NLM_LOCK_MSG,
                    (xdrproc_t)xdr_nlm4_lockargs, &arg4,
                    (xdrproc_t)xdr_void, &dummy, timeout);
        } else {
                arg.cookie.n_bytes = (char *)&msg->lm_msg_ident;
                arg.cookie.n_len = sizeof(msg->lm_msg_ident);
                arg.block = msg->lm_wait ? 1 : 0;
                arg.exclusive = msg->lm_fl.l_type == F_WRLCK ? 1 : 0;
                arg.alock.caller_name = hostname;
                arg.alock.fh.n_bytes = (char *)&msg->lm_fh;
                arg.alock.fh.n_len = msg->lm_fh_len;
                arg.alock.oh.n_bytes = (char *)&owner;
                arg.alock.oh.n_len = sizeof(owner);
                arg.alock.svid = msg->lm_msg_ident.pid;
                arg.alock.l_offset = msg->lm_fl.l_start;
                arg.alock.l_len = msg->lm_fl.l_len;
                arg.reclaim = 0;
                arg.state = nsm_state;

                if ((cli = get_client(
                    (struct sockaddr *)&msg->lm_addr,
                    NLM_VERS)) == NULL)
                        return (1);

                set_auth(cli, &msg->lm_cred);
                (void)clnt_call(cli, NLM_LOCK_MSG,
                    (xdrproc_t)xdr_nlm_lockargs, &arg,
                    (xdrproc_t)xdr_void, &dummy, timeout);
        }
        return (0);
}

/*
 * unlock_request --
 *      Convert an unlock LOCKD_MSG into an NLM request, and send it off.
 */
int
unlock_request(LOCKD_MSG *msg)
{
        CLIENT *cli;
        struct nlm4_unlockargs arg4;
        struct nlm_unlockargs arg;
        struct timeval timeout = {0, 0};        /* No timeout, no response. */
        char dummy;

        if (d_calls)
                syslog(LOG_DEBUG, "unlock request: %s: to %s",
                    msg->lm_nfsv3 ? "V4" : "V1/3",
                    from_addr((struct sockaddr *)&msg->lm_addr));

        if (msg->lm_nfsv3) {
                arg4.cookie.n_bytes = (char *)&msg->lm_msg_ident;
                arg4.cookie.n_len = sizeof(msg->lm_msg_ident);
                arg4.alock.caller_name = hostname;
                arg4.alock.fh.n_bytes = (char *)&msg->lm_fh;
                arg4.alock.fh.n_len = msg->lm_fh_len;
                arg4.alock.oh.n_bytes = (char *)&owner;
                arg4.alock.oh.n_len = sizeof(owner);
                arg4.alock.svid = msg->lm_msg_ident.pid;
                arg4.alock.l_offset = msg->lm_fl.l_start;
                arg4.alock.l_len = msg->lm_fl.l_len;

                if ((cli = get_client(
                    (struct sockaddr *)&msg->lm_addr,
                    NLM_VERS4)) == NULL)
                        return (1);

                set_auth(cli, &msg->lm_cred);
                (void)clnt_call(cli, NLM_UNLOCK_MSG,
                    (xdrproc_t)xdr_nlm4_unlockargs, &arg4,
                    (xdrproc_t)xdr_void, &dummy, timeout);
        } else {
                arg.cookie.n_bytes = (char *)&msg->lm_msg_ident;
                arg.cookie.n_len = sizeof(msg->lm_msg_ident);
                arg.alock.caller_name = hostname;
                arg.alock.fh.n_bytes = (char *)&msg->lm_fh;
                arg.alock.fh.n_len = msg->lm_fh_len;
                arg.alock.oh.n_bytes = (char *)&owner;
                arg.alock.oh.n_len = sizeof(owner);
                arg.alock.svid = msg->lm_msg_ident.pid;
                arg.alock.l_offset = msg->lm_fl.l_start;
                arg.alock.l_len = msg->lm_fl.l_len;

                if ((cli = get_client(
                    (struct sockaddr *)&msg->lm_addr,
                    NLM_VERS)) == NULL)
                        return (1);

                set_auth(cli, &msg->lm_cred);
                (void)clnt_call(cli, NLM_UNLOCK_MSG,
                    (xdrproc_t)xdr_nlm_unlockargs, &arg,
                    (xdrproc_t)xdr_void, &dummy, timeout);
        }

        return (0);
}

int
lock_answer(int pid, netobj *netcookie, int result, int *pid_p, int version)
{
        struct lockd_ans ans;

        if (netcookie->n_len != sizeof(ans.la_msg_ident)) {
                if (pid == -1) {        /* we're screwed */
                        syslog(LOG_ERR, "inedible nlm cookie");
                        return -1;
                }
                ans.la_msg_ident.pid = pid;
                ans.la_msg_ident.msg_seq = -1;
        } else {
                memcpy(&ans.la_msg_ident, netcookie->n_bytes,
                    sizeof(ans.la_msg_ident));
        }

        if (d_calls)
                syslog(LOG_DEBUG, "lock answer: pid %lu: %s %d",
                    (unsigned long)ans.la_msg_ident.pid,
                    version == NLM_VERS4 ? "nlmv4" : "nlmv3",
                    result);

        ans.la_set_getlk_pid = 0;
        if (version == NLM_VERS4)
                switch (result) {
                case nlm4_granted:
                        ans.la_errno = 0;
                        break;
                default:
                        ans.la_errno = EACCES;
                        break;
                case nlm4_denied:
                        if (pid_p == NULL)
                                ans.la_errno = EAGAIN;
                        else {
                                /* this is an answer to a nlm_test msg */
                                ans.la_set_getlk_pid = 1;
                                ans.la_getlk_pid = *pid_p;
                                ans.la_errno = 0;
                        }
                        break;
                case nlm4_denied_nolocks:
                        ans.la_errno = EAGAIN;
                        break;
                case nlm4_blocked:
                        return -1;
                        /* NOTREACHED */
                case nlm4_denied_grace_period:
                        ans.la_errno = EAGAIN;
                        break;
                case nlm4_deadlck:
                        ans.la_errno = EDEADLK;
                        break;
                case nlm4_rofs:
                        ans.la_errno = EROFS;
                        break;
                case nlm4_stale_fh:
                        ans.la_errno = ESTALE;
                        break;
                case nlm4_fbig:
                        ans.la_errno = EFBIG;
                        break;
                case nlm4_failed:
                        ans.la_errno = EACCES;
                        break;
                }
        else
                switch (result) {
                case nlm_granted:
                        ans.la_errno = 0;
                        break;
                default:
                        ans.la_errno = EACCES;
                        break;
                case nlm_denied:
                        if (pid_p == NULL)
                                ans.la_errno = EAGAIN;
                        else {
                                /* this is an answer to a nlm_test msg */
                                ans.la_set_getlk_pid = 1;
                                ans.la_getlk_pid = *pid_p;
                                ans.la_errno = 0;
                        }
                        break;
                case nlm_denied_nolocks:
                        ans.la_errno = EAGAIN;
                        break;
                case nlm_blocked:
                        return -1;
                        /* NOTREACHED */
                case nlm_denied_grace_period:
                        ans.la_errno = EAGAIN;
                        break;
                case nlm_deadlck:
                        ans.la_errno = EDEADLK;
                        break;
                }

        if (nfslockdans(LOCKD_ANS_VERSION, &ans)) {
                syslog(((errno == EPIPE || errno == ESRCH) ? 
                        LOG_INFO : LOG_ERR), 
                        "process %lu: %m", (u_long)ans.la_msg_ident.pid);
                return -1;
        }
        return 0;
}

/*
 * show --
 *      Display the contents of a kernel LOCKD_MSG structure.
 */
void
show(LOCKD_MSG *mp)
{
        static char hex[] = "0123456789abcdef";
        size_t len;
        u_int8_t *p, *t, buf[NFS_SMALLFH*3+1];

        syslog(LOG_DEBUG, "process ID: %lu\n", (long)mp->lm_msg_ident.pid);

        for (t = buf, p = (u_int8_t *)mp->lm_fh,
            len = mp->lm_fh_len;
            len > 0; ++p, --len) {
                *t++ = '\\';
                *t++ = hex[(*p & 0xf0) >> 4];
                *t++ = hex[*p & 0x0f];
        }
        *t = '\0';

        syslog(LOG_DEBUG, "fh_len %d, fh %s\n", (int)mp->lm_fh_len, buf);

        /* Show flock structure. */
        syslog(LOG_DEBUG, "start %llu; len %llu; pid %lu; type %d; whence %d\n",
            (unsigned long long)mp->lm_fl.l_start,
            (unsigned long long)mp->lm_fl.l_len, (u_long)mp->lm_fl.l_pid,
            mp->lm_fl.l_type, mp->lm_fl.l_whence);

        /* Show wait flag. */
        syslog(LOG_DEBUG, "wait was %s\n", mp->lm_wait ? "set" : "not set");
}