callback.c

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/*
 * linux/fs/nfs/callback.c
 *
 * Copyright (C) 2004 Trond Myklebust
 *
 * NFSv4 callback handling
 */

#include <linux/completion.h>
#include <linux/ip.h>
#include <linux/module.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/nfs_fs.h>
#include <linux/errno.h>
#include <linux/mutex.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/sunrpc/svcauth_gss.h>
#include <linux/sunrpc/bc_xprt.h>

#include <net/inet_sock.h>

#include "nfs4_fs.h"
#include "callback.h"
#include "internal.h"
#include "netns.h"

#define NFSDBG_FACILITY NFSDBG_CALLBACK

struct nfs_callback_data {
    unsigned int users;
    struct svc_serv *serv;
    struct svc_rqst *rqst;
    struct task_struct *task;
};

static struct nfs_callback_data nfs_callback_info[NFS4_MAX_MINOR_VERSION + 1];
static DEFINE_MUTEX(nfs_callback_mutex);
static struct svc_program nfs4_callback_program;

static int nfs4_callback_up_net(struct svc_serv *serv, struct net *net)
{
    int ret;
    struct nfs_net *nn = net_generic(net, nfs_net_id);

    ret = svc_create_xprt(serv, "tcp", net, PF_INET,
                nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
    if (ret <= 0)
        goto out_err;
    nn->nfs_callback_tcpport = ret;
    dprintk("NFS: Callback listener port = %u (af %u, net %p)\n",
            nn->nfs_callback_tcpport, PF_INET, net);

    ret = svc_create_xprt(serv, "tcp", net, PF_INET6,
                nfs_callback_set_tcpport, SVC_SOCK_ANONYMOUS);
    if (ret > 0) {
        nn->nfs_callback_tcpport6 = ret;
        dprintk("NFS: Callback listener port = %u (af %u, net %p)\n",
                nn->nfs_callback_tcpport6, PF_INET6, net);
    } else if (ret != -EAFNOSUPPORT)
        goto out_err;
    return 0;

out_err:
    return (ret) ? ret : -ENOMEM;
}

/*
 * This is the NFSv4 callback kernel thread.
 */
static int
nfs4_callback_svc(void *vrqstp)
{
    int err;
    struct svc_rqst *rqstp = vrqstp;

    set_freezable();

    while (!kthread_should_stop()) {
        /*
         * Listen for a request on the socket
         */
        err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
        if (err == -EAGAIN || err == -EINTR)
            continue;
        svc_process(rqstp);
    }
    return 0;
}

/*
 * Prepare to bring up the NFSv4 callback service
 */
static struct svc_rqst *
nfs4_callback_up(struct svc_serv *serv)
{
    return svc_prepare_thread(serv, &serv->sv_pools[0], NUMA_NO_NODE);
}

#if defined(CONFIG_NFS_V4_1)
static int nfs41_callback_up_net(struct svc_serv *serv, struct net *net)
{
    /*
     * Create an svc_sock for the back channel service that shares the
     * fore channel connection.
     * Returns the input port (0) and sets the svc_serv bc_xprt on success
     */
    return svc_create_xprt(serv, "tcp-bc", net, PF_INET, 0,
                  SVC_SOCK_ANONYMOUS);
}

/*
 * The callback service for NFSv4.1 callbacks
 */
static int
nfs41_callback_svc(void *vrqstp)
{
    struct svc_rqst *rqstp = vrqstp;
    struct svc_serv *serv = rqstp->rq_server;
    struct rpc_rqst *req;
    int error;
    DEFINE_WAIT(wq);

    set_freezable();

    while (!kthread_should_stop()) {
        prepare_to_wait(&serv->sv_cb_waitq, &wq, TASK_INTERRUPTIBLE);
        spin_lock_bh(&serv->sv_cb_lock);
        if (!list_empty(&serv->sv_cb_list)) {
            req = list_first_entry(&serv->sv_cb_list,
                    struct rpc_rqst, rq_bc_list);
            list_del(&req->rq_bc_list);
            spin_unlock_bh(&serv->sv_cb_lock);
            dprintk("Invoking bc_svc_process()\n");
            error = bc_svc_process(serv, req, rqstp);
            dprintk("bc_svc_process() returned w/ error code= %d\n",
                error);
        } else {
            spin_unlock_bh(&serv->sv_cb_lock);
            schedule();
        }
        finish_wait(&serv->sv_cb_waitq, &wq);
    }
    return 0;
}

/*
 * Bring up the NFSv4.1 callback service
 */
static struct svc_rqst *
nfs41_callback_up(struct svc_serv *serv)
{
    struct svc_rqst *rqstp;

    INIT_LIST_HEAD(&serv->sv_cb_list);
    spin_lock_init(&serv->sv_cb_lock);
    init_waitqueue_head(&serv->sv_cb_waitq);
    rqstp = svc_prepare_thread(serv, &serv->sv_pools[0], NUMA_NO_NODE);
    if (IS_ERR(rqstp)) {
        svc_xprt_put(serv->sv_bc_xprt);
        serv->sv_bc_xprt = NULL;
    }
    dprintk("--> %s return %ld\n", __func__,
        IS_ERR(rqstp) ? PTR_ERR(rqstp) : 0);
    return rqstp;
}

static void nfs_minorversion_callback_svc_setup(struct svc_serv *serv,
        struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
{
    *rqstpp = nfs41_callback_up(serv);
    *callback_svc = nfs41_callback_svc;
}

static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
        struct svc_serv *serv)
{
    if (minorversion)
        /*
         * Save the svc_serv in the transport so that it can
         * be referenced when the session backchannel is initialized
         */
        xprt->bc_serv = serv;
}
#else
static int nfs41_callback_up_net(struct svc_serv *serv, struct net *net)
{
    return 0;
}

static void nfs_minorversion_callback_svc_setup(struct svc_serv *serv,
        struct svc_rqst **rqstpp, int (**callback_svc)(void *vrqstp))
{
    *rqstpp = ERR_PTR(-ENOTSUPP);
    *callback_svc = ERR_PTR(-ENOTSUPP);
}

static inline void nfs_callback_bc_serv(u32 minorversion, struct rpc_xprt *xprt,
        struct svc_serv *serv)
{
}
#endif /* CONFIG_NFS_V4_1 */

static int nfs_callback_start_svc(int minorversion, struct rpc_xprt *xprt,
                  struct svc_serv *serv)
{
    struct svc_rqst *rqstp;
    int (*callback_svc)(void *vrqstp);
    struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
    char svc_name[12];
    int ret;

    nfs_callback_bc_serv(minorversion, xprt, serv);

    if (cb_info->task)
        return 0;

    switch (minorversion) {
    case 0:
        /* v4.0 callback setup */
        rqstp = nfs4_callback_up(serv);
        callback_svc = nfs4_callback_svc;
        break;
    default:
        nfs_minorversion_callback_svc_setup(serv,
                &rqstp, &callback_svc);
    }

    if (IS_ERR(rqstp))
        return PTR_ERR(rqstp);

    svc_sock_update_bufs(serv);

    sprintf(svc_name, "nfsv4.%u-svc", minorversion);
    cb_info->serv = serv;
    cb_info->rqst = rqstp;
    cb_info->task = kthread_run(callback_svc, cb_info->rqst, svc_name);
    if (IS_ERR(cb_info->task)) {
        ret = PTR_ERR(cb_info->task);
        svc_exit_thread(cb_info->rqst);
        cb_info->rqst = NULL;
        cb_info->task = NULL;
        return ret;
    }
    dprintk("nfs_callback_up: service started\n");
    return 0;
}

static void nfs_callback_down_net(u32 minorversion, struct svc_serv *serv, struct net *net)
{
    struct nfs_net *nn = net_generic(net, nfs_net_id);

    if (--nn->cb_users[minorversion])
        return;

    dprintk("NFS: destroy per-net callback data; net=%p\n", net);
    svc_shutdown_net(serv, net);
}

static int nfs_callback_up_net(int minorversion, struct svc_serv *serv, struct net *net)
{
    struct nfs_net *nn = net_generic(net, nfs_net_id);
    int ret;

    if (nn->cb_users[minorversion]++)
        return 0;

    dprintk("NFS: create per-net callback data; net=%p\n", net);

    ret = svc_bind(serv, net);
    if (ret < 0) {
        printk(KERN_WARNING "NFS: bind callback service failed\n");
        goto err_bind;
    }

    switch (minorversion) {
        case 0:
            ret = nfs4_callback_up_net(serv, net);
            break;
        case 1:
            ret = nfs41_callback_up_net(serv, net);
            break;
        default:
            printk(KERN_ERR "NFS: unknown callback version: %d\n",
                    minorversion);
            ret = -EINVAL;
            break;
    }

    if (ret < 0) {
        printk(KERN_ERR "NFS: callback service start failed\n");
        goto err_socks;
    }
    return 0;

err_socks:
    svc_rpcb_cleanup(serv, net);
err_bind:
    dprintk("NFS: Couldn't create callback socket: err = %d; "
            "net = %p\n", ret, net);
    return ret;
}

static struct svc_serv *nfs_callback_create_svc(int minorversion)
{
    struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
    struct svc_serv *serv;

    /*
     * Check whether we're already up and running.
     */
    if (cb_info->task) {
        /*
         * Note: increase service usage, because later in case of error
         * svc_destroy() will be called.
         */
        svc_get(cb_info->serv);
        return cb_info->serv;
    }

    /*
     * Sanity check: if there's no task,
     * we should be the first user ...
     */
    if (cb_info->users)
        printk(KERN_WARNING "nfs_callback_create_svc: no kthread, %d users??\n",
            cb_info->users);

    serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
    if (!serv) {
        printk(KERN_ERR "nfs_callback_create_svc: create service failed\n");
        return ERR_PTR(-ENOMEM);
    }
    /* As there is only one thread we need to over-ride the
     * default maximum of 80 connections
     */
    serv->sv_maxconn = 1024;
    dprintk("nfs_callback_create_svc: service created\n");
    return serv;
}

/*
 * Bring up the callback thread if it is not already up.
 */
int nfs_callback_up(u32 minorversion, struct rpc_xprt *xprt)
{
    struct svc_serv *serv;
    struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];
    int ret;
    struct net *net = xprt->xprt_net;

    mutex_lock(&nfs_callback_mutex);

    serv = nfs_callback_create_svc(minorversion);
    if (IS_ERR(serv)) {
        ret = PTR_ERR(serv);
        goto err_create;
    }

    ret = nfs_callback_up_net(minorversion, serv, net);
    if (ret < 0)
        goto err_net;

    ret = nfs_callback_start_svc(minorversion, xprt, serv);
    if (ret < 0)
        goto err_start;

    cb_info->users++;
    /*
     * svc_create creates the svc_serv with sv_nrthreads == 1, and then
     * svc_prepare_thread increments that. So we need to call svc_destroy
     * on both success and failure so that the refcount is 1 when the
     * thread exits.
     */
err_net:
    svc_destroy(serv);
err_create:
    mutex_unlock(&nfs_callback_mutex);
    return ret;

err_start:
    nfs_callback_down_net(minorversion, serv, net);
    dprintk("NFS: Couldn't create server thread; err = %d\n", ret);
    goto err_net;
}

/*
 * Kill the callback thread if it's no longer being used.
 */
void nfs_callback_down(int minorversion, struct net *net)
{
    struct nfs_callback_data *cb_info = &nfs_callback_info[minorversion];

    mutex_lock(&nfs_callback_mutex);
    nfs_callback_down_net(minorversion, cb_info->serv, net);
    cb_info->users--;
    if (cb_info->users == 0 && cb_info->task != NULL) {
        kthread_stop(cb_info->task);
        dprintk("nfs_callback_down: service stopped\n");
        svc_exit_thread(cb_info->rqst);
        dprintk("nfs_callback_down: service destroyed\n");
        cb_info->serv = NULL;
        cb_info->rqst = NULL;
        cb_info->task = NULL;
    }
    mutex_unlock(&nfs_callback_mutex);
}

/* Boolean check of RPC_AUTH_GSS principal */
int
check_gss_callback_principal(struct nfs_client *clp, struct svc_rqst *rqstp)
{
    char *p = rqstp->rq_cred.cr_principal;

    if (rqstp->rq_authop->flavour != RPC_AUTH_GSS)
        return 1;

    /* No RPC_AUTH_GSS on NFSv4.1 back channel yet */
    if (clp->cl_minorversion != 0)
        return 0;
    /*
     * It might just be a normal user principal, in which case
     * userspace won't bother to tell us the name at all.
     */
    if (p == NULL)
        return 0;

    /* Expect a GSS_C_NT_HOSTBASED_NAME like "nfs@serverhostname" */

    if (memcmp(p, "nfs@", 4) != 0)
        return 0;
    p += 4;
    if (strcmp(p, clp->cl_hostname) != 0)
        return 0;
    return 1;
}

/*
 * pg_authenticate method for nfsv4 callback threads.
 *
 * The authflavor has been negotiated, so an incorrect flavor is a server
 * bug. Drop packets with incorrect authflavor.
 *
 * All other checking done after NFS decoding where the nfs_client can be
 * found in nfs4_callback_compound
 */
static int nfs_callback_authenticate(struct svc_rqst *rqstp)
{
    switch (rqstp->rq_authop->flavour) {
    case RPC_AUTH_NULL:
        if (rqstp->rq_proc != CB_NULL)
            return SVC_DROP;
        break;
    case RPC_AUTH_GSS:
        /* No RPC_AUTH_GSS support yet in NFSv4.1 */
         if (svc_is_backchannel(rqstp))
            return SVC_DROP;
    }
    return SVC_OK;
}

/*
 * Define NFS4 callback program
 */
static struct svc_version *nfs4_callback_version[] = {
    [1] = &nfs4_callback_version1,
    [4] = &nfs4_callback_version4,
};

static struct svc_stat nfs4_callback_stats;

static struct svc_program nfs4_callback_program = {
    .pg_prog = NFS4_CALLBACK,           /* RPC service number */
    .pg_nvers = ARRAY_SIZE(nfs4_callback_version),  /* Number of entries */
    .pg_vers = nfs4_callback_version,       /* version table */
    .pg_name = "NFSv4 callback",            /* service name */
    .pg_class = "nfs",              /* authentication class */
    .pg_stats = &nfs4_callback_stats,
    .pg_authenticate = nfs_callback_authenticate,
};