// SPDX-License-Identifier: GPL-2.0-only
/*
 * Syscall interface to knfsd.
 *
 * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
 */

#include <linux/slab.h>
#include <linux/namei.h>
#include <linux/ctype.h>
#include <linux/fs_context.h>

#include <linux/sunrpc/svcsock.h>
#include <linux/lockd/lockd.h>
#include <linux/sunrpc/addr.h>
#include <linux/sunrpc/gss_api.h>
#include <linux/sunrpc/gss_krb5_enctypes.h>
#include <linux/sunrpc/rpc_pipe_fs.h>
#include <linux/module.h>
#include <linux/fsnotify.h>

#include "idmap.h"
#include "nfsd.h"
#include "cache.h"
#include "state.h"
#include "netns.h"
#include "pnfs.h"

/*
 *      We have a single directory with several nodes in it.
 */
enum {
        NFSD_Root = 1,
        NFSD_List,
        NFSD_Export_Stats,
        NFSD_Export_features,
        NFSD_Fh,
        NFSD_FO_UnlockIP,
        NFSD_FO_UnlockFS,
        NFSD_Threads,
        NFSD_Pool_Threads,
        NFSD_Pool_Stats,
        NFSD_Reply_Cache_Stats,
        NFSD_Versions,
        NFSD_Ports,
        NFSD_MaxBlkSize,
        NFSD_MaxConnections,
        NFSD_SupportedEnctypes,
        /*
         * The below MUST come last.  Otherwise we leave a hole in nfsd_files[]
         * with !CONFIG_NFSD_V4 and simple_fill_super() goes oops
         */
#ifdef CONFIG_NFSD_V4
        NFSD_Leasetime,
        NFSD_Gracetime,
        NFSD_RecoveryDir,
        NFSD_V4EndGrace,
#endif
        NFSD_MaxReserved
};

/*
 * write() for these nodes.
 */
static ssize_t write_filehandle(struct file *file, char *buf, size_t size);
static ssize_t write_unlock_ip(struct file *file, char *buf, size_t size);
static ssize_t write_unlock_fs(struct file *file, char *buf, size_t size);
static ssize_t write_threads(struct file *file, char *buf, size_t size);
static ssize_t write_pool_threads(struct file *file, char *buf, size_t size);
static ssize_t write_versions(struct file *file, char *buf, size_t size);
static ssize_t write_ports(struct file *file, char *buf, size_t size);
static ssize_t write_maxblksize(struct file *file, char *buf, size_t size);
static ssize_t write_maxconn(struct file *file, char *buf, size_t size);
#ifdef CONFIG_NFSD_V4
static ssize_t write_leasetime(struct file *file, char *buf, size_t size);
static ssize_t write_gracetime(struct file *file, char *buf, size_t size);
static ssize_t write_recoverydir(struct file *file, char *buf, size_t size);
static ssize_t write_v4_end_grace(struct file *file, char *buf, size_t size);
#endif

static ssize_t (*const write_op[])(struct file *, char *, size_t) = {
        [NFSD_Fh] = write_filehandle,
        [NFSD_FO_UnlockIP] = write_unlock_ip,
        [NFSD_FO_UnlockFS] = write_unlock_fs,
        [NFSD_Threads] = write_threads,
        [NFSD_Pool_Threads] = write_pool_threads,
        [NFSD_Versions] = write_versions,
        [NFSD_Ports] = write_ports,
        [NFSD_MaxBlkSize] = write_maxblksize,
        [NFSD_MaxConnections] = write_maxconn,
#ifdef CONFIG_NFSD_V4
        [NFSD_Leasetime] = write_leasetime,
        [NFSD_Gracetime] = write_gracetime,
        [NFSD_RecoveryDir] = write_recoverydir,
        [NFSD_V4EndGrace] = write_v4_end_grace,
#endif
};

static ssize_t nfsctl_transaction_write(struct file *file, const char __user *buf, size_t size, loff_t *pos)
{
        ino_t ino =  file_inode(file)->i_ino;
        char *data;
        ssize_t rv;

        if (ino >= ARRAY_SIZE(write_op) || !write_op[ino])
                return -EINVAL;

        data = simple_transaction_get(file, buf, size);
        if (IS_ERR(data))
                return PTR_ERR(data);

        rv =  write_op[ino](file, data, size);
        if (rv >= 0) {
                simple_transaction_set(file, rv);
                rv = size;
        }
        return rv;
}

static ssize_t nfsctl_transaction_read(struct file *file, char __user *buf, size_t size, loff_t *pos)
{
        if (! file->private_data) {
                /* An attempt to read a transaction file without writing
                 * causes a 0-byte write so that the file can return
                 * state information
                 */
                ssize_t rv = nfsctl_transaction_write(file, buf, 0, pos);
                if (rv < 0)
                        return rv;
        }
        return simple_transaction_read(file, buf, size, pos);
}

static const struct file_operations transaction_ops = {
        .write          = nfsctl_transaction_write,
        .read           = nfsctl_transaction_read,
        .release        = simple_transaction_release,
        .llseek         = default_llseek,
};

static int exports_net_open(struct net *net, struct file *file)
{
        int err;
        struct seq_file *seq;
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        err = seq_open(file, &nfs_exports_op);
        if (err)
                return err;

        seq = file->private_data;
        seq->private = nn->svc_export_cache;
        return 0;
}

static int exports_proc_open(struct inode *inode, struct file *file)
{
        return exports_net_open(current->nsproxy->net_ns, file);
}

static const struct proc_ops exports_proc_ops = {
        .proc_open      = exports_proc_open,
        .proc_read      = seq_read,
        .proc_lseek     = seq_lseek,
        .proc_release   = seq_release,
};

static int exports_nfsd_open(struct inode *inode, struct file *file)
{
        return exports_net_open(inode->i_sb->s_fs_info, file);
}

static const struct file_operations exports_nfsd_operations = {
        .open           = exports_nfsd_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = seq_release,
};

static int export_features_show(struct seq_file *m, void *v)
{
        seq_printf(m, "0x%x 0x%x\n", NFSEXP_ALLFLAGS, NFSEXP_SECINFO_FLAGS);
        return 0;
}

static int export_features_open(struct inode *inode, struct file *file)
{
        return single_open(file, export_features_show, NULL);
}

static const struct file_operations export_features_operations = {
        .open           = export_features_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

#if defined(CONFIG_SUNRPC_GSS) || defined(CONFIG_SUNRPC_GSS_MODULE)
static int supported_enctypes_show(struct seq_file *m, void *v)
{
        seq_printf(m, KRB5_SUPPORTED_ENCTYPES);
        return 0;
}

static int supported_enctypes_open(struct inode *inode, struct file *file)
{
        return single_open(file, supported_enctypes_show, NULL);
}

static const struct file_operations supported_enctypes_ops = {
        .open           = supported_enctypes_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};
#endif /* CONFIG_SUNRPC_GSS or CONFIG_SUNRPC_GSS_MODULE */

static const struct file_operations pool_stats_operations = {
        .open           = nfsd_pool_stats_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = nfsd_pool_stats_release,
};

static const struct file_operations reply_cache_stats_operations = {
        .open           = nfsd_reply_cache_stats_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

/*----------------------------------------------------------------------------*/
/*
 * payload - write methods
 */

static inline struct net *netns(struct file *file)
{
        return file_inode(file)->i_sb->s_fs_info;
}

/*
 * write_unlock_ip - Release all locks used by a client
 *
 * Experimental.
 *
 * Input:
 *                      buf:    '\n'-terminated C string containing a
 *                              presentation format IP address
 *                      size:   length of C string in @buf
 * Output:
 *      On success:     returns zero if all specified locks were released;
 *                      returns one if one or more locks were not released
 *      On error:       return code is negative errno value
 */
static ssize_t write_unlock_ip(struct file *file, char *buf, size_t size)
{
        struct sockaddr_storage address;
        struct sockaddr *sap = (struct sockaddr *)&address;
        size_t salen = sizeof(address);
        char *fo_path;
        struct net *net = netns(file);

        /* sanity check */
        if (size == 0)
                return -EINVAL;

        if (buf[size-1] != '\n')
                return -EINVAL;

        fo_path = buf;
        if (qword_get(&buf, fo_path, size) < 0)
                return -EINVAL;

        if (rpc_pton(net, fo_path, size, sap, salen) == 0)
                return -EINVAL;

        return nlmsvc_unlock_all_by_ip(sap);
}

/*
 * write_unlock_fs - Release all locks on a local file system
 *
 * Experimental.
 *
 * Input:
 *                      buf:    '\n'-terminated C string containing the
 *                              absolute pathname of a local file system
 *                      size:   length of C string in @buf
 * Output:
 *      On success:     returns zero if all specified locks were released;
 *                      returns one if one or more locks were not released
 *      On error:       return code is negative errno value
 */
static ssize_t write_unlock_fs(struct file *file, char *buf, size_t size)
{
        struct path path;
        char *fo_path;
        int error;

        /* sanity check */
        if (size == 0)
                return -EINVAL;

        if (buf[size-1] != '\n')
                return -EINVAL;

        fo_path = buf;
        if (qword_get(&buf, fo_path, size) < 0)
                return -EINVAL;

        error = kern_path(fo_path, 0, &path);
        if (error)
                return error;

        /*
         * XXX: Needs better sanity checking.  Otherwise we could end up
         * releasing locks on the wrong file system.
         *
         * For example:
         * 1.  Does the path refer to a directory?
         * 2.  Is that directory a mount point, or
         * 3.  Is that directory the root of an exported file system?
         */
        error = nlmsvc_unlock_all_by_sb(path.dentry->d_sb);

        path_put(&path);
        return error;
}

/*
 * write_filehandle - Get a variable-length NFS file handle by path
 *
 * On input, the buffer contains a '\n'-terminated C string comprised of
 * three alphanumeric words separated by whitespace.  The string may
 * contain escape sequences.
 *
 * Input:
 *                      buf:
 *                              domain:         client domain name
 *                              path:           export pathname
 *                              maxsize:        numeric maximum size of
 *                                              @buf
 *                      size:   length of C string in @buf
 * Output:
 *      On success:     passed-in buffer filled with '\n'-terminated C
 *                      string containing a ASCII hex text version
 *                      of the NFS file handle;
 *                      return code is the size in bytes of the string
 *      On error:       return code is negative errno value
 */
static ssize_t write_filehandle(struct file *file, char *buf, size_t size)
{
        char *dname, *path;
        int maxsize;
        char *mesg = buf;
        int len;
        struct auth_domain *dom;
        struct knfsd_fh fh;

        if (size == 0)
                return -EINVAL;

        if (buf[size-1] != '\n')
                return -EINVAL;
        buf[size-1] = 0;

        dname = mesg;
        len = qword_get(&mesg, dname, size);
        if (len <= 0)
                return -EINVAL;
        
        path = dname+len+1;
        len = qword_get(&mesg, path, size);
        if (len <= 0)
                return -EINVAL;

        len = get_int(&mesg, &maxsize);
        if (len)
                return len;

        if (maxsize < NFS_FHSIZE)
                return -EINVAL;
        maxsize = min(maxsize, NFS3_FHSIZE);

        if (qword_get(&mesg, mesg, size)>0)
                return -EINVAL;

        /* we have all the words, they are in buf.. */
        dom = unix_domain_find(dname);
        if (!dom)
                return -ENOMEM;

        len = exp_rootfh(netns(file), dom, path, &fh,  maxsize);
        auth_domain_put(dom);
        if (len)
                return len;
        
        mesg = buf;
        len = SIMPLE_TRANSACTION_LIMIT;
        qword_addhex(&mesg, &len, (char*)&fh.fh_base, fh.fh_size);
        mesg[-1] = '\n';
        return mesg - buf;      
}

/*
 * write_threads - Start NFSD, or report the current number of running threads
 *
 * Input:
 *                      buf:            ignored
 *                      size:           zero
 * Output:
 *      On success:     passed-in buffer filled with '\n'-terminated C
 *                      string numeric value representing the number of
 *                      running NFSD threads;
 *                      return code is the size in bytes of the string
 *      On error:       return code is zero
 *
 * OR
 *
 * Input:
 *                      buf:            C string containing an unsigned
 *                                      integer value representing the
 *                                      number of NFSD threads to start
 *                      size:           non-zero length of C string in @buf
 * Output:
 *      On success:     NFS service is started;
 *                      passed-in buffer filled with '\n'-terminated C
 *                      string numeric value representing the number of
 *                      running NFSD threads;
 *                      return code is the size in bytes of the string
 *      On error:       return code is zero or a negative errno value
 */
static ssize_t write_threads(struct file *file, char *buf, size_t size)
{
        char *mesg = buf;
        int rv;
        struct net *net = netns(file);

        if (size > 0) {
                int newthreads;
                rv = get_int(&mesg, &newthreads);
                if (rv)
                        return rv;
                if (newthreads < 0)
                        return -EINVAL;
                rv = nfsd_svc(newthreads, net, file->f_cred);
                if (rv < 0)
                        return rv;
        } else
                rv = nfsd_nrthreads(net);

        return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%d\n", rv);
}

/*
 * write_pool_threads - Set or report the current number of threads per pool
 *
 * Input:
 *                      buf:            ignored
 *                      size:           zero
 *
 * OR
 *
 * Input:
 *                      buf:            C string containing whitespace-
 *                                      separated unsigned integer values
 *                                      representing the number of NFSD
 *                                      threads to start in each pool
 *                      size:           non-zero length of C string in @buf
 * Output:
 *      On success:     passed-in buffer filled with '\n'-terminated C
 *                      string containing integer values representing the
 *                      number of NFSD threads in each pool;
 *                      return code is the size in bytes of the string
 *      On error:       return code is zero or a negative errno value
 */
static ssize_t write_pool_threads(struct file *file, char *buf, size_t size)
{
        /* if size > 0, look for an array of number of threads per node
         * and apply them  then write out number of threads per node as reply
         */
        char *mesg = buf;
        int i;
        int rv;
        int len;
        int npools;
        int *nthreads;
        struct net *net = netns(file);

        mutex_lock(&nfsd_mutex);
        npools = nfsd_nrpools(net);
        if (npools == 0) {
                /*
                 * NFS is shut down.  The admin can start it by
                 * writing to the threads file but NOT the pool_threads
                 * file, sorry.  Report zero threads.
                 */
                mutex_unlock(&nfsd_mutex);
                strcpy(buf, "0\n");
                return strlen(buf);
        }

        nthreads = kcalloc(npools, sizeof(int), GFP_KERNEL);
        rv = -ENOMEM;
        if (nthreads == NULL)
                goto out_free;

        if (size > 0) {
                for (i = 0; i < npools; i++) {
                        rv = get_int(&mesg, &nthreads[i]);
                        if (rv == -ENOENT)
                                break;          /* fewer numbers than pools */
                        if (rv)
                                goto out_free;  /* syntax error */
                        rv = -EINVAL;
                        if (nthreads[i] < 0)
                                goto out_free;
                }
                rv = nfsd_set_nrthreads(i, nthreads, net);
                if (rv)
                        goto out_free;
        }

        rv = nfsd_get_nrthreads(npools, nthreads, net);
        if (rv)
                goto out_free;

        mesg = buf;
        size = SIMPLE_TRANSACTION_LIMIT;
        for (i = 0; i < npools && size > 0; i++) {
                snprintf(mesg, size, "%d%c", nthreads[i], (i == npools-1 ? '\n' : ' '));
                len = strlen(mesg);
                size -= len;
                mesg += len;
        }
        rv = mesg - buf;
out_free:
        kfree(nthreads);
        mutex_unlock(&nfsd_mutex);
        return rv;
}

static ssize_t
nfsd_print_version_support(struct nfsd_net *nn, char *buf, int remaining,
                const char *sep, unsigned vers, int minor)
{
        const char *format = minor < 0 ? "%s%c%u" : "%s%c%u.%u";
        bool supported = !!nfsd_vers(nn, vers, NFSD_TEST);

        if (vers == 4 && minor >= 0 &&
            !nfsd_minorversion(nn, minor, NFSD_TEST))
                supported = false;
        if (minor == 0 && supported)
                /*
                 * special case for backward compatability.
                 * +4.0 is never reported, it is implied by
                 * +4, unless -4.0 is present.
                 */
                return 0;
        return snprintf(buf, remaining, format, sep,
                        supported ? '+' : '-', vers, minor);
}

static ssize_t __write_versions(struct file *file, char *buf, size_t size)
{
        char *mesg = buf;
        char *vers, *minorp, sign;
        int len, num, remaining;
        ssize_t tlen = 0;
        char *sep;
        struct nfsd_net *nn = net_generic(netns(file), nfsd_net_id);

        if (size>0) {
                if (nn->nfsd_serv)
                        /* Cannot change versions without updating
                         * nn->nfsd_serv->sv_xdrsize, and reallocing
                         * rq_argp and rq_resp
                         */
                        return -EBUSY;
                if (buf[size-1] != '\n')
                        return -EINVAL;
                buf[size-1] = 0;

                vers = mesg;
                len = qword_get(&mesg, vers, size);
                if (len <= 0) return -EINVAL;
                do {
                        enum vers_op cmd;
                        unsigned minor;
                        sign = *vers;
                        if (sign == '+' || sign == '-')
                                num = simple_strtol((vers+1), &minorp, 0);
                        else
                                num = simple_strtol(vers, &minorp, 0);
                        if (*minorp == '.') {
                                if (num != 4)
                                        return -EINVAL;
                                if (kstrtouint(minorp+1, 0, &minor) < 0)
                                        return -EINVAL;
                        }

                        cmd = sign == '-' ? NFSD_CLEAR : NFSD_SET;
                        switch(num) {
                        case 2:
                        case 3:
                                nfsd_vers(nn, num, cmd);
                                break;
                        case 4:
                                if (*minorp == '.') {
                                        if (nfsd_minorversion(nn, minor, cmd) < 0)
                                                return -EINVAL;
                                } else if ((cmd == NFSD_SET) != nfsd_vers(nn, num, NFSD_TEST)) {
                                        /*
                                         * Either we have +4 and no minors are enabled,
                                         * or we have -4 and at least one minor is enabled.
                                         * In either case, propagate 'cmd' to all minors.
                                         */
                                        minor = 0;
                                        while (nfsd_minorversion(nn, minor, cmd) >= 0)
                                                minor++;
                                }
                                break;
                        default:
                                return -EINVAL;
                        }
                        vers += len + 1;
                } while ((len = qword_get(&mesg, vers, size)) > 0);
                /* If all get turned off, turn them back on, as
                 * having no versions is BAD
                 */
                nfsd_reset_versions(nn);
        }

        /* Now write current state into reply buffer */
        len = 0;
        sep = "";
        remaining = SIMPLE_TRANSACTION_LIMIT;
        for (num=2 ; num <= 4 ; num++) {
                int minor;
                if (!nfsd_vers(nn, num, NFSD_AVAIL))
                        continue;

                minor = -1;
                do {
                        len = nfsd_print_version_support(nn, buf, remaining,
                                        sep, num, minor);
                        if (len >= remaining)
                                goto out;
                        remaining -= len;
                        buf += len;
                        tlen += len;
                        minor++;
                        if (len)
                                sep = " ";
                } while (num == 4 && minor <= NFSD_SUPPORTED_MINOR_VERSION);
        }
out:
        len = snprintf(buf, remaining, "\n");
        if (len >= remaining)
                return -EINVAL;
        return tlen + len;
}

/*
 * write_versions - Set or report the available NFS protocol versions
 *
 * Input:
 *                      buf:            ignored
 *                      size:           zero
 * Output:
 *      On success:     passed-in buffer filled with '\n'-terminated C
 *                      string containing positive or negative integer
 *                      values representing the current status of each
 *                      protocol version;
 *                      return code is the size in bytes of the string
 *      On error:       return code is zero or a negative errno value
 *
 * OR
 *
 * Input:
 *                      buf:            C string containing whitespace-
 *                                      separated positive or negative
 *                                      integer values representing NFS
 *                                      protocol versions to enable ("+n")
 *                                      or disable ("-n")
 *                      size:           non-zero length of C string in @buf
 * Output:
 *      On success:     status of zero or more protocol versions has
 *                      been updated; passed-in buffer filled with
 *                      '\n'-terminated C string containing positive
 *                      or negative integer values representing the
 *                      current status of each protocol version;
 *                      return code is the size in bytes of the string
 *      On error:       return code is zero or a negative errno value
 */
static ssize_t write_versions(struct file *file, char *buf, size_t size)
{
        ssize_t rv;

        mutex_lock(&nfsd_mutex);
        rv = __write_versions(file, buf, size);
        mutex_unlock(&nfsd_mutex);
        return rv;
}

/*
 * Zero-length write.  Return a list of NFSD's current listener
 * transports.
 */
static ssize_t __write_ports_names(char *buf, struct net *net)
{
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        if (nn->nfsd_serv == NULL)
                return 0;
        return svc_xprt_names(nn->nfsd_serv, buf, SIMPLE_TRANSACTION_LIMIT);
}

/*
 * A single 'fd' number was written, in which case it must be for
 * a socket of a supported family/protocol, and we use it as an
 * nfsd listener.
 */
static ssize_t __write_ports_addfd(char *buf, struct net *net, const struct cred *cred)
{
        char *mesg = buf;
        int fd, err;
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        err = get_int(&mesg, &fd);
        if (err != 0 || fd < 0)
                return -EINVAL;

        if (svc_alien_sock(net, fd)) {
                printk(KERN_ERR "%s: socket net is different to NFSd's one\n", __func__);
                return -EINVAL;
        }

        err = nfsd_create_serv(net);
        if (err != 0)
                return err;

        err = svc_addsock(nn->nfsd_serv, fd, buf, SIMPLE_TRANSACTION_LIMIT, cred);
        if (err < 0) {
                nfsd_destroy(net);
                return err;
        }

        /* Decrease the count, but don't shut down the service */
        nn->nfsd_serv->sv_nrthreads--;
        return err;
}

/*
 * A transport listener is added by writing it's transport name and
 * a port number.
 */
static ssize_t __write_ports_addxprt(char *buf, struct net *net, const struct cred *cred)
{
        char transport[16];
        struct svc_xprt *xprt;
        int port, err;
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        if (sscanf(buf, "%15s %5u", transport, &port) != 2)
                return -EINVAL;

        if (port < 1 || port > USHRT_MAX)
                return -EINVAL;

        err = nfsd_create_serv(net);
        if (err != 0)
                return err;

        err = svc_create_xprt(nn->nfsd_serv, transport, net,
                                PF_INET, port, SVC_SOCK_ANONYMOUS, cred);
        if (err < 0)
                goto out_err;

        err = svc_create_xprt(nn->nfsd_serv, transport, net,
                                PF_INET6, port, SVC_SOCK_ANONYMOUS, cred);
        if (err < 0 && err != -EAFNOSUPPORT)
                goto out_close;

        /* Decrease the count, but don't shut down the service */
        nn->nfsd_serv->sv_nrthreads--;
        return 0;
out_close:
        xprt = svc_find_xprt(nn->nfsd_serv, transport, net, PF_INET, port);
        if (xprt != NULL) {
                svc_close_xprt(xprt);
                svc_xprt_put(xprt);
        }
out_err:
        nfsd_destroy(net);
        return err;
}

static ssize_t __write_ports(struct file *file, char *buf, size_t size,
                             struct net *net)
{
        if (size == 0)
                return __write_ports_names(buf, net);

        if (isdigit(buf[0]))
                return __write_ports_addfd(buf, net, file->f_cred);

        if (isalpha(buf[0]))
                return __write_ports_addxprt(buf, net, file->f_cred);

        return -EINVAL;
}

/*
 * write_ports - Pass a socket file descriptor or transport name to listen on
 *
 * Input:
 *                      buf:            ignored
 *                      size:           zero
 * Output:
 *      On success:     passed-in buffer filled with a '\n'-terminated C
 *                      string containing a whitespace-separated list of
 *                      named NFSD listeners;
 *                      return code is the size in bytes of the string
 *      On error:       return code is zero or a negative errno value
 *
 * OR
 *
 * Input:
 *                      buf:            C string containing an unsigned
 *                                      integer value representing a bound
 *                                      but unconnected socket that is to be
 *                                      used as an NFSD listener; listen(3)
 *                                      must be called for a SOCK_STREAM
 *                                      socket, otherwise it is ignored
 *                      size:           non-zero length of C string in @buf
 * Output:
 *      On success:     NFS service is started;
 *                      passed-in buffer filled with a '\n'-terminated C
 *                      string containing a unique alphanumeric name of
 *                      the listener;
 *                      return code is the size in bytes of the string
 *      On error:       return code is a negative errno value
 *
 * OR
 *
 * Input:
 *                      buf:            C string containing a transport
 *                                      name and an unsigned integer value
 *                                      representing the port to listen on,
 *                                      separated by whitespace
 *                      size:           non-zero length of C string in @buf
 * Output:
 *      On success:     returns zero; NFS service is started
 *      On error:       return code is a negative errno value
 */
static ssize_t write_ports(struct file *file, char *buf, size_t size)
{
        ssize_t rv;

        mutex_lock(&nfsd_mutex);
        rv = __write_ports(file, buf, size, netns(file));
        mutex_unlock(&nfsd_mutex);
        return rv;
}


int nfsd_max_blksize;

/*
 * write_maxblksize - Set or report the current NFS blksize
 *
 * Input:
 *                      buf:            ignored
 *                      size:           zero
 *
 * OR
 *
 * Input:
 *                      buf:            C string containing an unsigned
 *                                      integer value representing the new
 *                                      NFS blksize
 *                      size:           non-zero length of C string in @buf
 * Output:
 *      On success:     passed-in buffer filled with '\n'-terminated C string
 *                      containing numeric value of the current NFS blksize
 *                      setting;
 *                      return code is the size in bytes of the string
 *      On error:       return code is zero or a negative errno value
 */
static ssize_t write_maxblksize(struct file *file, char *buf, size_t size)
{
        char *mesg = buf;
        struct nfsd_net *nn = net_generic(netns(file), nfsd_net_id);

        if (size > 0) {
                int bsize;
                int rv = get_int(&mesg, &bsize);
                if (rv)
                        return rv;
                /* force bsize into allowed range and
                 * required alignment.
                 */
                bsize = max_t(int, bsize, 1024);
                bsize = min_t(int, bsize, NFSSVC_MAXBLKSIZE);
                bsize &= ~(1024-1);
                mutex_lock(&nfsd_mutex);
                if (nn->nfsd_serv) {
                        mutex_unlock(&nfsd_mutex);
                        return -EBUSY;
                }
                nfsd_max_blksize = bsize;
                mutex_unlock(&nfsd_mutex);
        }

        return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%d\n",
                                                        nfsd_max_blksize);
}

/*
 * write_maxconn - Set or report the current max number of connections
 *
 * Input:
 *                      buf:            ignored
 *                      size:           zero
 * OR
 *
 * Input:
 *                      buf:            C string containing an unsigned
 *                                      integer value representing the new
 *                                      number of max connections
 *                      size:           non-zero length of C string in @buf
 * Output:
 *      On success:     passed-in buffer filled with '\n'-terminated C string
 *                      containing numeric value of max_connections setting
 *                      for this net namespace;
 *                      return code is the size in bytes of the string
 *      On error:       return code is zero or a negative errno value
 */
static ssize_t write_maxconn(struct file *file, char *buf, size_t size)
{
        char *mesg = buf;
        struct nfsd_net *nn = net_generic(netns(file), nfsd_net_id);
        unsigned int maxconn = nn->max_connections;

        if (size > 0) {
                int rv = get_uint(&mesg, &maxconn);

                if (rv)
                        return rv;
                nn->max_connections = maxconn;
        }

        return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%u\n", maxconn);
}

#ifdef CONFIG_NFSD_V4
static ssize_t __nfsd4_write_time(struct file *file, char *buf, size_t size,
                                  time64_t *time, struct nfsd_net *nn)
{
        char *mesg = buf;
        int rv, i;

        if (size > 0) {
                if (nn->nfsd_serv)
                        return -EBUSY;
                rv = get_int(&mesg, &i);
                if (rv)
                        return rv;
                /*
                 * Some sanity checking.  We don't have a reason for
                 * these particular numbers, but problems with the
                 * extremes are:
                 *      - Too short: the briefest network outage may
                 *        cause clients to lose all their locks.  Also,
                 *        the frequent polling may be wasteful.
                 *      - Too long: do you really want reboot recovery
                 *        to take more than an hour?  Or to make other
                 *        clients wait an hour before being able to
                 *        revoke a dead client's locks?
                 */
                if (i < 10 || i > 3600)
                        return -EINVAL;
                *time = i;
        }

        return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%lld\n", *time);
}

static ssize_t nfsd4_write_time(struct file *file, char *buf, size_t size,
                                time64_t *time, struct nfsd_net *nn)
{
        ssize_t rv;

        mutex_lock(&nfsd_mutex);
        rv = __nfsd4_write_time(file, buf, size, time, nn);
        mutex_unlock(&nfsd_mutex);
        return rv;
}

/*
 * write_leasetime - Set or report the current NFSv4 lease time
 *
 * Input:
 *                      buf:            ignored
 *                      size:           zero
 *
 * OR
 *
 * Input:
 *                      buf:            C string containing an unsigned
 *                                      integer value representing the new
 *                                      NFSv4 lease expiry time
 *                      size:           non-zero length of C string in @buf
 * Output:
 *      On success:     passed-in buffer filled with '\n'-terminated C
 *                      string containing unsigned integer value of the
 *                      current lease expiry time;
 *                      return code is the size in bytes of the string
 *      On error:       return code is zero or a negative errno value
 */
static ssize_t write_leasetime(struct file *file, char *buf, size_t size)
{
        struct nfsd_net *nn = net_generic(netns(file), nfsd_net_id);
        return nfsd4_write_time(file, buf, size, &nn->nfsd4_lease, nn);
}

/*
 * write_gracetime - Set or report current NFSv4 grace period time
 *
 * As above, but sets the time of the NFSv4 grace period.
 *
 * Note this should never be set to less than the *previous*
 * lease-period time, but we don't try to enforce this.  (In the common
 * case (a new boot), we don't know what the previous lease time was
 * anyway.)
 */
static ssize_t write_gracetime(struct file *file, char *buf, size_t size)
{
        struct nfsd_net *nn = net_generic(netns(file), nfsd_net_id);
        return nfsd4_write_time(file, buf, size, &nn->nfsd4_grace, nn);
}

static ssize_t __write_recoverydir(struct file *file, char *buf, size_t size,
                                   struct nfsd_net *nn)
{
        char *mesg = buf;
        char *recdir;
        int len, status;

        if (size > 0) {
                if (nn->nfsd_serv)
                        return -EBUSY;
                if (size > PATH_MAX || buf[size-1] != '\n')
                        return -EINVAL;
                buf[size-1] = 0;

                recdir = mesg;
                len = qword_get(&mesg, recdir, size);
                if (len <= 0)
                        return -EINVAL;

                status = nfs4_reset_recoverydir(recdir);
                if (status)
                        return status;
        }

        return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%s\n",
                                                        nfs4_recoverydir());
}

/*
 * write_recoverydir - Set or report the pathname of the recovery directory
 *
 * Input:
 *                      buf:            ignored
 *                      size:           zero
 *
 * OR
 *
 * Input:
 *                      buf:            C string containing the pathname
 *                                      of the directory on a local file
 *                                      system containing permanent NFSv4
 *                                      recovery data
 *                      size:           non-zero length of C string in @buf
 * Output:
 *      On success:     passed-in buffer filled with '\n'-terminated C string
 *                      containing the current recovery pathname setting;
 *                      return code is the size in bytes of the string
 *      On error:       return code is zero or a negative errno value
 */
static ssize_t write_recoverydir(struct file *file, char *buf, size_t size)
{
        ssize_t rv;
        struct nfsd_net *nn = net_generic(netns(file), nfsd_net_id);

        mutex_lock(&nfsd_mutex);
        rv = __write_recoverydir(file, buf, size, nn);
        mutex_unlock(&nfsd_mutex);
        return rv;
}

/*
 * write_v4_end_grace - release grace period for nfsd's v4.x lock manager
 *
 * Input:
 *                      buf:            ignored
 *                      size:           zero
 * OR
 *
 * Input:
 *                      buf:            any value
 *                      size:           non-zero length of C string in @buf
 * Output:
 *                      passed-in buffer filled with "Y" or "N" with a newline
 *                      and NULL-terminated C string. This indicates whether
 *                      the grace period has ended in the current net
 *                      namespace. Return code is the size in bytes of the
 *                      string. Writing a string that starts with 'Y', 'y', or
 *                      '1' to the file will end the grace period for nfsd's v4
 *                      lock manager.
 */
static ssize_t write_v4_end_grace(struct file *file, char *buf, size_t size)
{
        struct nfsd_net *nn = net_generic(netns(file), nfsd_net_id);

        if (size > 0) {
                switch(buf[0]) {
                case 'Y':
                case 'y':
                case '1':
                        if (!nn->nfsd_serv)
                                return -EBUSY;
                        nfsd4_end_grace(nn);
                        break;
                default:
                        return -EINVAL;
                }
        }

        return scnprintf(buf, SIMPLE_TRANSACTION_LIMIT, "%c\n",
                         nn->grace_ended ? 'Y' : 'N');
}

#endif

/*----------------------------------------------------------------------------*/
/*
 *      populating the filesystem.
 */

/* Basically copying rpc_get_inode. */
static struct inode *nfsd_get_inode(struct super_block *sb, umode_t mode)
{
        struct inode *inode = new_inode(sb);
        if (!inode)
                return NULL;
        /* Following advice from simple_fill_super documentation: */
        inode->i_ino = iunique(sb, NFSD_MaxReserved);
        inode->i_mode = mode;
        inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
        switch (mode & S_IFMT) {
        case S_IFDIR:
                inode->i_fop = &simple_dir_operations;
                inode->i_op = &simple_dir_inode_operations;
                inc_nlink(inode);
        default:
                break;
        }
        return inode;
}

static int __nfsd_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode, struct nfsdfs_client *ncl)
{
        struct inode *inode;

        inode = nfsd_get_inode(dir->i_sb, mode);
        if (!inode)
                return -ENOMEM;
        if (ncl) {
                inode->i_private = ncl;
                kref_get(&ncl->cl_ref);
        }
        d_add(dentry, inode);
        inc_nlink(dir);
        fsnotify_mkdir(dir, dentry);
        return 0;
}

static struct dentry *nfsd_mkdir(struct dentry *parent, struct nfsdfs_client *ncl, char *name)
{
        struct inode *dir = parent->d_inode;
        struct dentry *dentry;
        int ret = -ENOMEM;

        inode_lock(dir);
        dentry = d_alloc_name(parent, name);
        if (!dentry)
                goto out_err;
        ret = __nfsd_mkdir(d_inode(parent), dentry, S_IFDIR | 0600, ncl);
        if (ret)
                goto out_err;
out:
        inode_unlock(dir);
        return dentry;
out_err:
        dput(dentry);
        dentry = ERR_PTR(ret);
        goto out;
}

static void clear_ncl(struct inode *inode)
{
        struct nfsdfs_client *ncl = inode->i_private;

        inode->i_private = NULL;
        kref_put(&ncl->cl_ref, ncl->cl_release);
}

static struct nfsdfs_client *__get_nfsdfs_client(struct inode *inode)
{
        struct nfsdfs_client *nc = inode->i_private;

        if (nc)
                kref_get(&nc->cl_ref);
        return nc;
}

struct nfsdfs_client *get_nfsdfs_client(struct inode *inode)
{
        struct nfsdfs_client *nc;

        inode_lock_shared(inode);
        nc = __get_nfsdfs_client(inode);
        inode_unlock_shared(inode);
        return nc;
}
/* from __rpc_unlink */
static void nfsdfs_remove_file(struct inode *dir, struct dentry *dentry)
{
        int ret;

        clear_ncl(d_inode(dentry));
        dget(dentry);
        ret = simple_unlink(dir, dentry);
        d_delete(dentry);
        dput(dentry);
        WARN_ON_ONCE(ret);
}

static void nfsdfs_remove_files(struct dentry *root)
{
        struct dentry *dentry, *tmp;

        list_for_each_entry_safe(dentry, tmp, &root->d_subdirs, d_child) {
                if (!simple_positive(dentry)) {
                        WARN_ON_ONCE(1); /* I think this can't happen? */
                        continue;
                }
                nfsdfs_remove_file(d_inode(root), dentry);
        }
}

/* XXX: cut'n'paste from simple_fill_super; figure out if we could share
 * code instead. */
static  int nfsdfs_create_files(struct dentry *root,
                                        const struct tree_descr *files)
{
        struct inode *dir = d_inode(root);
        struct inode *inode;
        struct dentry *dentry;
        int i;

        inode_lock(dir);
        for (i = 0; files->name && files->name[0]; i++, files++) {
                if (!files->name)
                        continue;
                dentry = d_alloc_name(root, files->name);
                if (!dentry)
                        goto out;
                inode = nfsd_get_inode(d_inode(root)->i_sb,
                                        S_IFREG | files->mode);
                if (!inode) {
                        dput(dentry);
                        goto out;
                }
                inode->i_fop = files->ops;
                inode->i_private = __get_nfsdfs_client(dir);
                d_add(dentry, inode);
                fsnotify_create(dir, dentry);
        }
        inode_unlock(dir);
        return 0;
out:
        nfsdfs_remove_files(root);
        inode_unlock(dir);
        return -ENOMEM;
}

/* on success, returns positive number unique to that client. */
struct dentry *nfsd_client_mkdir(struct nfsd_net *nn,
                struct nfsdfs_client *ncl, u32 id,
                const struct tree_descr *files)
{
        struct dentry *dentry;
        char name[11];
        int ret;

        sprintf(name, "%u", id);

        dentry = nfsd_mkdir(nn->nfsd_client_dir, ncl, name);
        if (IS_ERR(dentry)) /* XXX: tossing errors? */
                return NULL;
        ret = nfsdfs_create_files(dentry, files);
        if (ret) {
                nfsd_client_rmdir(dentry);
                return NULL;
        }
        return dentry;
}

/* Taken from __rpc_rmdir: */
void nfsd_client_rmdir(struct dentry *dentry)
{
        struct inode *dir = d_inode(dentry->d_parent);
        struct inode *inode = d_inode(dentry);
        int ret;

        inode_lock(dir);
        nfsdfs_remove_files(dentry);
        clear_ncl(inode);
        dget(dentry);
        ret = simple_rmdir(dir, dentry);
        WARN_ON_ONCE(ret);
        fsnotify_rmdir(dir, dentry);
        d_delete(dentry);
        dput(dentry);
        inode_unlock(dir);
}

static int nfsd_fill_super(struct super_block *sb, struct fs_context *fc)
{
        struct nfsd_net *nn = net_generic(current->nsproxy->net_ns,
                                                        nfsd_net_id);
        struct dentry *dentry;
        int ret;

        static const struct tree_descr nfsd_files[] = {
                [NFSD_List] = {"exports", &exports_nfsd_operations, S_IRUGO},
                /* Per-export io stats use same ops as exports file */
                [NFSD_Export_Stats] = {"export_stats", &exports_nfsd_operations, S_IRUGO},
                [NFSD_Export_features] = {"export_features",
                                        &export_features_operations, S_IRUGO},
                [NFSD_FO_UnlockIP] = {"unlock_ip",
                                        &transaction_ops, S_IWUSR|S_IRUSR},
                [NFSD_FO_UnlockFS] = {"unlock_filesystem",
                                        &transaction_ops, S_IWUSR|S_IRUSR},
                [NFSD_Fh] = {"filehandle", &transaction_ops, S_IWUSR|S_IRUSR},
                [NFSD_Threads] = {"threads", &transaction_ops, S_IWUSR|S_IRUSR},
                [NFSD_Pool_Threads] = {"pool_threads", &transaction_ops, S_IWUSR|S_IRUSR},
                [NFSD_Pool_Stats] = {"pool_stats", &pool_stats_operations, S_IRUGO},
                [NFSD_Reply_Cache_Stats] = {"reply_cache_stats", &reply_cache_stats_operations, S_IRUGO},
                [NFSD_Versions] = {"versions", &transaction_ops, S_IWUSR|S_IRUSR},
                [NFSD_Ports] = {"portlist", &transaction_ops, S_IWUSR|S_IRUGO},
                [NFSD_MaxBlkSize] = {"max_block_size", &transaction_ops, S_IWUSR|S_IRUGO},
                [NFSD_MaxConnections] = {"max_connections", &transaction_ops, S_IWUSR|S_IRUGO},
#if defined(CONFIG_SUNRPC_GSS) || defined(CONFIG_SUNRPC_GSS_MODULE)
                [NFSD_SupportedEnctypes] = {"supported_krb5_enctypes", &supported_enctypes_ops, S_IRUGO},
#endif /* CONFIG_SUNRPC_GSS or CONFIG_SUNRPC_GSS_MODULE */
#ifdef CONFIG_NFSD_V4
                [NFSD_Leasetime] = {"nfsv4leasetime", &transaction_ops, S_IWUSR|S_IRUSR},
                [NFSD_Gracetime] = {"nfsv4gracetime", &transaction_ops, S_IWUSR|S_IRUSR},
                [NFSD_RecoveryDir] = {"nfsv4recoverydir", &transaction_ops, S_IWUSR|S_IRUSR},
                [NFSD_V4EndGrace] = {"v4_end_grace", &transaction_ops, S_IWUSR|S_IRUGO},
#endif
                /* last one */ {""}
        };

        ret = simple_fill_super(sb, 0x6e667364, nfsd_files);
        if (ret)
                return ret;
        dentry = nfsd_mkdir(sb->s_root, NULL, "clients");
        if (IS_ERR(dentry))
                return PTR_ERR(dentry);
        nn->nfsd_client_dir = dentry;
        return 0;
}

static int nfsd_fs_get_tree(struct fs_context *fc)
{
        return get_tree_keyed(fc, nfsd_fill_super, get_net(fc->net_ns));
}

static void nfsd_fs_free_fc(struct fs_context *fc)
{
        if (fc->s_fs_info)
                put_net(fc->s_fs_info);
}

static const struct fs_context_operations nfsd_fs_context_ops = {
        .free           = nfsd_fs_free_fc,
        .get_tree       = nfsd_fs_get_tree,
};

static int nfsd_init_fs_context(struct fs_context *fc)
{
        put_user_ns(fc->user_ns);
        fc->user_ns = get_user_ns(fc->net_ns->user_ns);
        fc->ops = &nfsd_fs_context_ops;
        return 0;
}

static void nfsd_umount(struct super_block *sb)
{
        struct net *net = sb->s_fs_info;

        kill_litter_super(sb);
        put_net(net);
}

static struct file_system_type nfsd_fs_type = {
        .owner          = THIS_MODULE,
        .name           = "nfsd",
        .init_fs_context = nfsd_init_fs_context,
        .kill_sb        = nfsd_umount,
};
MODULE_ALIAS_FS("nfsd");

int get_nfsdfs(struct net *net)
{
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);
        struct vfsmount *mnt;

        mnt =  vfs_kern_mount(&nfsd_fs_type, SB_KERNMOUNT, "nfsd", NULL);
        if (IS_ERR(mnt))
                return PTR_ERR(mnt);
        nn->nfsd_mnt = mnt;
        return 0;
}

#ifdef CONFIG_PROC_FS
static int create_proc_exports_entry(void)
{
        struct proc_dir_entry *entry;

        entry = proc_mkdir("fs/nfs", NULL);
        if (!entry)
                return -ENOMEM;
        entry = proc_create("exports", 0, entry, &exports_proc_ops);
        if (!entry) {
                remove_proc_entry("fs/nfs", NULL);
                return -ENOMEM;
        }
        return 0;
}
#else /* CONFIG_PROC_FS */
static int create_proc_exports_entry(void)
{
        return 0;
}
#endif

unsigned int nfsd_net_id;

static __net_init int nfsd_init_net(struct net *net)
{
        int retval;
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        retval = nfsd_export_init(net);
        if (retval)
                goto out_export_error;
        retval = nfsd_idmap_init(net);
        if (retval)
                goto out_idmap_error;
        nn->nfsd_versions = NULL;
        nn->nfsd4_minorversions = NULL;
        retval = nfsd_reply_cache_init(nn);
        if (retval)
                goto out_drc_error;
        nn->nfsd4_lease = 90;   /* default lease time */
        nn->nfsd4_grace = 90;
        nn->somebody_reclaimed = false;
        nn->track_reclaim_completes = false;
        nn->clverifier_counter = prandom_u32();
        nn->clientid_base = prandom_u32();
        nn->clientid_counter = nn->clientid_base + 1;
        nn->s2s_cp_cl_id = nn->clientid_counter++;

        atomic_set(&nn->ntf_refcnt, 0);
        init_waitqueue_head(&nn->ntf_wq);
        seqlock_init(&nn->boot_lock);

        return 0;

out_drc_error:
        nfsd_idmap_shutdown(net);
out_idmap_error:
        nfsd_export_shutdown(net);
out_export_error:
        return retval;
}

static __net_exit void nfsd_exit_net(struct net *net)
{
        struct nfsd_net *nn = net_generic(net, nfsd_net_id);

        nfsd_reply_cache_shutdown(nn);
        nfsd_idmap_shutdown(net);
        nfsd_export_shutdown(net);
        nfsd_netns_free_versions(net_generic(net, nfsd_net_id));
}

static struct pernet_operations nfsd_net_ops = {
        .init = nfsd_init_net,
        .exit = nfsd_exit_net,
        .id   = &nfsd_net_id,
        .size = sizeof(struct nfsd_net),
};

static int __init init_nfsd(void)
{
        int retval;
        printk(KERN_INFO "Installing knfsd (copyright (C) 1996 okir@monad.swb.de).\n");

        retval = register_cld_notifier();
        if (retval)
                return retval;
        retval = nfsd4_init_slabs();
        if (retval)
                goto out_unregister_notifier;
        retval = nfsd4_init_pnfs();
        if (retval)
                goto out_free_slabs;
        retval = nfsd_stat_init();      /* Statistics */
        if (retval)
                goto out_free_pnfs;
        retval = nfsd_drc_slab_create();
        if (retval)
                goto out_free_stat;
        nfsd_lockd_init();      /* lockd->nfsd callbacks */
        retval = create_proc_exports_entry();
        if (retval)
                goto out_free_lockd;
        retval = register_filesystem(&nfsd_fs_type);
        if (retval)
                goto out_free_exports;
        retval = register_pernet_subsys(&nfsd_net_ops);
        if (retval < 0)
                goto out_free_all;
        return 0;
out_free_all:
        unregister_pernet_subsys(&nfsd_net_ops);
out_free_exports:
        remove_proc_entry("fs/nfs/exports", NULL);
        remove_proc_entry("fs/nfs", NULL);
out_free_lockd:
        nfsd_lockd_shutdown();
        nfsd_drc_slab_free();
out_free_stat:
        nfsd_stat_shutdown();
out_free_pnfs:
        nfsd4_exit_pnfs();
out_free_slabs:
        nfsd4_free_slabs();
out_unregister_notifier:
        unregister_cld_notifier();
        return retval;
}

static void __exit exit_nfsd(void)
{
        unregister_pernet_subsys(&nfsd_net_ops);
        nfsd_drc_slab_free();
        remove_proc_entry("fs/nfs/exports", NULL);
        remove_proc_entry("fs/nfs", NULL);
        nfsd_stat_shutdown();
        nfsd_lockd_shutdown();
        nfsd4_free_slabs();
        nfsd4_exit_pnfs();
        unregister_filesystem(&nfsd_fs_type);
        unregister_cld_notifier();
}

MODULE_AUTHOR("Olaf Kirch <okir@monad.swb.de>");
MODULE_LICENSE("GPL");
module_init(init_nfsd)
module_exit(exit_nfsd)