mon.c

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/*
 * linux/fs/lockd/mon.c
 *
 * The kernel statd client.
 *
 * Copyright (C) 1996, Olaf Kirch <[email protected]>
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/ktime.h>
#include <linux/slab.h>

#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/xprtsock.h>
#include <linux/sunrpc/svc.h>
#include <linux/lockd/lockd.h>

#include <asm/unaligned.h>

#include "netns.h"

#define NLMDBG_FACILITY     NLMDBG_MONITOR
#define NSM_PROGRAM     100024
#define NSM_VERSION     1

enum {
    NSMPROC_NULL,
    NSMPROC_STAT,
    NSMPROC_MON,
    NSMPROC_UNMON,
    NSMPROC_UNMON_ALL,
    NSMPROC_SIMU_CRASH,
    NSMPROC_NOTIFY,
};

struct nsm_args {
    struct nsm_private  *priv;
    u32         prog;       /* RPC callback info */
    u32         vers;
    u32         proc;

    char            *mon_name;
    char            *nodename;
};

struct nsm_res {
    u32         status;
    u32         state;
};

static const struct rpc_program nsm_program;
static              LIST_HEAD(nsm_handles);
static              DEFINE_SPINLOCK(nsm_lock);

/*
 * Local NSM state
 */
u32 __read_mostly       nsm_local_state;
bool    __read_mostly       nsm_use_hostnames;

static inline struct sockaddr *nsm_addr(const struct nsm_handle *nsm)
{
    return (struct sockaddr *)&nsm->sm_addr;
}

static struct rpc_clnt *nsm_create(struct net *net)
{
    struct sockaddr_in sin = {
        .sin_family     = AF_INET,
        .sin_addr.s_addr    = htonl(INADDR_LOOPBACK),
    };
    struct rpc_create_args args = {
        .net            = net,
        .protocol       = XPRT_TRANSPORT_TCP,
        .address        = (struct sockaddr *)&sin,
        .addrsize       = sizeof(sin),
        .servername     = "rpc.statd",
        .program        = &nsm_program,
        .version        = NSM_VERSION,
        .authflavor     = RPC_AUTH_NULL,
        .flags          = RPC_CLNT_CREATE_NOPING,
    };

    return rpc_create(&args);
}

static struct rpc_clnt *nsm_client_set(struct lockd_net *ln,
        struct rpc_clnt *clnt)
{
    spin_lock(&ln->nsm_clnt_lock);
    if (ln->nsm_users == 0) {
        if (clnt == NULL)
            goto out;
        ln->nsm_clnt = clnt;
    }
    clnt = ln->nsm_clnt;
    ln->nsm_users++;
out:
    spin_unlock(&ln->nsm_clnt_lock);
    return clnt;
}

static struct rpc_clnt *nsm_client_get(struct net *net)
{
    struct rpc_clnt *clnt, *new;
    struct lockd_net *ln = net_generic(net, lockd_net_id);

    clnt = nsm_client_set(ln, NULL);
    if (clnt != NULL)
        goto out;

    clnt = new = nsm_create(net);
    if (IS_ERR(clnt))
        goto out;

    clnt = nsm_client_set(ln, new);
    if (clnt != new)
        rpc_shutdown_client(new);
out:
    return clnt;
}

static void nsm_client_put(struct net *net)
{
    struct lockd_net *ln = net_generic(net, lockd_net_id);
    struct rpc_clnt *clnt = NULL;

    spin_lock(&ln->nsm_clnt_lock);
    ln->nsm_users--;
    if (ln->nsm_users == 0) {
        clnt = ln->nsm_clnt;
        ln->nsm_clnt = NULL;
    }
    spin_unlock(&ln->nsm_clnt_lock);
    if (clnt != NULL)
        rpc_shutdown_client(clnt);
}

static int nsm_mon_unmon(struct nsm_handle *nsm, u32 proc, struct nsm_res *res,
             struct rpc_clnt *clnt)
{
    int     status;
    struct nsm_args args = {
        .priv       = &nsm->sm_priv,
        .prog       = NLM_PROGRAM,
        .vers       = 3,
        .proc       = NLMPROC_NSM_NOTIFY,
        .mon_name   = nsm->sm_mon_name,
        .nodename   = clnt->cl_nodename,
    };
    struct rpc_message msg = {
        .rpc_argp   = &args,
        .rpc_resp   = res,
    };

    BUG_ON(clnt == NULL);

    memset(res, 0, sizeof(*res));

    msg.rpc_proc = &clnt->cl_procinfo[proc];
    status = rpc_call_sync(clnt, &msg, RPC_TASK_SOFTCONN);
    if (status < 0)
        dprintk("lockd: NSM upcall RPC failed, status=%d\n",
                status);
    else
        status = 0;
    return status;
}

int nsm_monitor(const struct nlm_host *host)
{
    struct nsm_handle *nsm = host->h_nsmhandle;
    struct nsm_res  res;
    int     status;
    struct rpc_clnt *clnt;

    dprintk("lockd: nsm_monitor(%s)\n", nsm->sm_name);

    if (nsm->sm_monitored)
        return 0;

    /*
     * Choose whether to record the caller_name or IP address of
     * this peer in the local rpc.statd's database.
     */
    nsm->sm_mon_name = nsm_use_hostnames ? nsm->sm_name : nsm->sm_addrbuf;

    clnt = nsm_client_get(host->net);
    if (IS_ERR(clnt)) {
        status = PTR_ERR(clnt);
        dprintk("lockd: failed to create NSM upcall transport, "
                "status=%d, net=%p\n", status, host->net);
        return status;
    }

    status = nsm_mon_unmon(nsm, NSMPROC_MON, &res, clnt);
    if (unlikely(res.status != 0))
        status = -EIO;
    if (unlikely(status < 0)) {
        printk(KERN_NOTICE "lockd: cannot monitor %s\n", nsm->sm_name);
        return status;
    }

    nsm->sm_monitored = 1;
    if (unlikely(nsm_local_state != res.state)) {
        nsm_local_state = res.state;
        dprintk("lockd: NSM state changed to %d\n", nsm_local_state);
    }
    return 0;
}

void nsm_unmonitor(const struct nlm_host *host)
{
    struct nsm_handle *nsm = host->h_nsmhandle;
    struct nsm_res  res;
    int status;

    if (atomic_read(&nsm->sm_count) == 1
     && nsm->sm_monitored && !nsm->sm_sticky) {
        struct lockd_net *ln = net_generic(host->net, lockd_net_id);

        dprintk("lockd: nsm_unmonitor(%s)\n", nsm->sm_name);

        status = nsm_mon_unmon(nsm, NSMPROC_UNMON, &res, ln->nsm_clnt);
        if (res.status != 0)
            status = -EIO;
        if (status < 0)
            printk(KERN_NOTICE "lockd: cannot unmonitor %s\n",
                    nsm->sm_name);
        else
            nsm->sm_monitored = 0;

        nsm_client_put(host->net);
    }
}

static struct nsm_handle *nsm_lookup_hostname(const char *hostname,
                          const size_t len)
{
    struct nsm_handle *nsm;

    list_for_each_entry(nsm, &nsm_handles, sm_link)
        if (strlen(nsm->sm_name) == len &&
            memcmp(nsm->sm_name, hostname, len) == 0)
            return nsm;
    return NULL;
}

static struct nsm_handle *nsm_lookup_addr(const struct sockaddr *sap)
{
    struct nsm_handle *nsm;

    list_for_each_entry(nsm, &nsm_handles, sm_link)
        if (rpc_cmp_addr(nsm_addr(nsm), sap))
            return nsm;
    return NULL;
}

static struct nsm_handle *nsm_lookup_priv(const struct nsm_private *priv)
{
    struct nsm_handle *nsm;

    list_for_each_entry(nsm, &nsm_handles, sm_link)
        if (memcmp(nsm->sm_priv.data, priv->data,
                    sizeof(priv->data)) == 0)
            return nsm;
    return NULL;
}

/*
 * Construct a unique cookie to match this nsm_handle to this monitored
 * host.  It is passed to the local rpc.statd via NSMPROC_MON, and
 * returned via NLMPROC_SM_NOTIFY, in the "priv" field of these
 * requests.
 *
 * The NSM protocol requires that these cookies be unique while the
 * system is running.  We prefer a stronger requirement of making them
 * unique across reboots.  If user space bugs cause a stale cookie to
 * be sent to the kernel, it could cause the wrong host to lose its
 * lock state if cookies were not unique across reboots.
 *
 * The cookies are exposed only to local user space via loopback.  They
 * do not appear on the physical network.  If we want greater security
 * for some reason, nsm_init_private() could perform a one-way hash to
 * obscure the contents of the cookie.
 */
static void nsm_init_private(struct nsm_handle *nsm)
{
    u64 *p = (u64 *)&nsm->sm_priv.data;
    struct timespec ts;
    s64 ns;

    ktime_get_ts(&ts);
    ns = timespec_to_ns(&ts);
    put_unaligned(ns, p);
    put_unaligned((unsigned long)nsm, p + 1);
}

static struct nsm_handle *nsm_create_handle(const struct sockaddr *sap,
                        const size_t salen,
                        const char *hostname,
                        const size_t hostname_len)
{
    struct nsm_handle *new;

    new = kzalloc(sizeof(*new) + hostname_len + 1, GFP_KERNEL);
    if (unlikely(new == NULL))
        return NULL;

    atomic_set(&new->sm_count, 1);
    new->sm_name = (char *)(new + 1);
    memcpy(nsm_addr(new), sap, salen);
    new->sm_addrlen = salen;
    nsm_init_private(new);

    if (rpc_ntop(nsm_addr(new), new->sm_addrbuf,
                    sizeof(new->sm_addrbuf)) == 0)
        (void)snprintf(new->sm_addrbuf, sizeof(new->sm_addrbuf),
                "unsupported address family");
    memcpy(new->sm_name, hostname, hostname_len);
    new->sm_name[hostname_len] = '\0';

    return new;
}

struct nsm_handle *nsm_get_handle(const struct sockaddr *sap,
                  const size_t salen, const char *hostname,
                  const size_t hostname_len)
{
    struct nsm_handle *cached, *new = NULL;

    if (hostname && memchr(hostname, '/', hostname_len) != NULL) {
        if (printk_ratelimit()) {
            printk(KERN_WARNING "Invalid hostname \"%.*s\" "
                        "in NFS lock request\n",
                (int)hostname_len, hostname);
        }
        return NULL;
    }

retry:
    spin_lock(&nsm_lock);

    if (nsm_use_hostnames && hostname != NULL)
        cached = nsm_lookup_hostname(hostname, hostname_len);
    else
        cached = nsm_lookup_addr(sap);

    if (cached != NULL) {
        atomic_inc(&cached->sm_count);
        spin_unlock(&nsm_lock);
        kfree(new);
        dprintk("lockd: found nsm_handle for %s (%s), "
                "cnt %d\n", cached->sm_name,
                cached->sm_addrbuf,
                atomic_read(&cached->sm_count));
        return cached;
    }

    if (new != NULL) {
        list_add(&new->sm_link, &nsm_handles);
        spin_unlock(&nsm_lock);
        dprintk("lockd: created nsm_handle for %s (%s)\n",
                new->sm_name, new->sm_addrbuf);
        return new;
    }

    spin_unlock(&nsm_lock);

    new = nsm_create_handle(sap, salen, hostname, hostname_len);
    if (unlikely(new == NULL))
        return NULL;
    goto retry;
}

struct nsm_handle *nsm_reboot_lookup(const struct nlm_reboot *info)
{
    struct nsm_handle *cached;

    spin_lock(&nsm_lock);

    cached = nsm_lookup_priv(&info->priv);
    if (unlikely(cached == NULL)) {
        spin_unlock(&nsm_lock);
        dprintk("lockd: never saw rebooted peer '%.*s' before\n",
                info->len, info->mon);
        return cached;
    }

    atomic_inc(&cached->sm_count);
    spin_unlock(&nsm_lock);

    dprintk("lockd: host %s (%s) rebooted, cnt %d\n",
            cached->sm_name, cached->sm_addrbuf,
            atomic_read(&cached->sm_count));
    return cached;
}

void nsm_release(struct nsm_handle *nsm)
{
    if (atomic_dec_and_lock(&nsm->sm_count, &nsm_lock)) {
        list_del(&nsm->sm_link);
        spin_unlock(&nsm_lock);
        dprintk("lockd: destroyed nsm_handle for %s (%s)\n",
                nsm->sm_name, nsm->sm_addrbuf);
        kfree(nsm);
    }
}

/*
 * XDR functions for NSM.
 *
 * See http://www.opengroup.org/ for details on the Network
 * Status Monitor wire protocol.
 */

static void encode_nsm_string(struct xdr_stream *xdr, const char *string)
{
    const u32 len = strlen(string);
    __be32 *p;

    BUG_ON(len > SM_MAXSTRLEN);
    p = xdr_reserve_space(xdr, 4 + len);
    xdr_encode_opaque(p, string, len);
}

/*
 * "mon_name" specifies the host to be monitored.
 */
static void encode_mon_name(struct xdr_stream *xdr, const struct nsm_args *argp)
{
    encode_nsm_string(xdr, argp->mon_name);
}

/*
 * The "my_id" argument specifies the hostname and RPC procedure
 * to be called when the status manager receives notification
 * (via the NLMPROC_SM_NOTIFY call) that the state of host "mon_name"
 * has changed.
 */
static void encode_my_id(struct xdr_stream *xdr, const struct nsm_args *argp)
{
    __be32 *p;

    encode_nsm_string(xdr, argp->nodename);
    p = xdr_reserve_space(xdr, 4 + 4 + 4);
    *p++ = cpu_to_be32(argp->prog);
    *p++ = cpu_to_be32(argp->vers);
    *p = cpu_to_be32(argp->proc);
}

/*
 * The "mon_id" argument specifies the non-private arguments
 * of an NSMPROC_MON or NSMPROC_UNMON call.
 */
static void encode_mon_id(struct xdr_stream *xdr, const struct nsm_args *argp)
{
    encode_mon_name(xdr, argp);
    encode_my_id(xdr, argp);
}

/*
 * The "priv" argument may contain private information required
 * by the NSMPROC_MON call. This information will be supplied in the
 * NLMPROC_SM_NOTIFY call.
 */
static void encode_priv(struct xdr_stream *xdr, const struct nsm_args *argp)
{
    __be32 *p;

    p = xdr_reserve_space(xdr, SM_PRIV_SIZE);
    xdr_encode_opaque_fixed(p, argp->priv->data, SM_PRIV_SIZE);
}

static void nsm_xdr_enc_mon(struct rpc_rqst *req, struct xdr_stream *xdr,
                const struct nsm_args *argp)
{
    encode_mon_id(xdr, argp);
    encode_priv(xdr, argp);
}

static void nsm_xdr_enc_unmon(struct rpc_rqst *req, struct xdr_stream *xdr,
                  const struct nsm_args *argp)
{
    encode_mon_id(xdr, argp);
}

static int nsm_xdr_dec_stat_res(struct rpc_rqst *rqstp,
                struct xdr_stream *xdr,
                struct nsm_res *resp)
{
    __be32 *p;

    p = xdr_inline_decode(xdr, 4 + 4);
    if (unlikely(p == NULL))
        return -EIO;
    resp->status = be32_to_cpup(p++);
    resp->state = be32_to_cpup(p);

    dprintk("lockd: %s status %d state %d\n",
        __func__, resp->status, resp->state);
    return 0;
}

static int nsm_xdr_dec_stat(struct rpc_rqst *rqstp,
                struct xdr_stream *xdr,
                struct nsm_res *resp)
{
    __be32 *p;

    p = xdr_inline_decode(xdr, 4);
    if (unlikely(p == NULL))
        return -EIO;
    resp->state = be32_to_cpup(p);

    dprintk("lockd: %s state %d\n", __func__, resp->state);
    return 0;
}

#define SM_my_name_sz   (1+XDR_QUADLEN(SM_MAXSTRLEN))
#define SM_my_id_sz (SM_my_name_sz+3)
#define SM_mon_name_sz  (1+XDR_QUADLEN(SM_MAXSTRLEN))
#define SM_mon_id_sz    (SM_mon_name_sz+SM_my_id_sz)
#define SM_priv_sz  (XDR_QUADLEN(SM_PRIV_SIZE))
#define SM_mon_sz   (SM_mon_id_sz+SM_priv_sz)
#define SM_monres_sz    2
#define SM_unmonres_sz  1

static struct rpc_procinfo  nsm_procedures[] = {
[NSMPROC_MON] = {
        .p_proc     = NSMPROC_MON,
        .p_encode   = (kxdreproc_t)nsm_xdr_enc_mon,
        .p_decode   = (kxdrdproc_t)nsm_xdr_dec_stat_res,
        .p_arglen   = SM_mon_sz,
        .p_replen   = SM_monres_sz,
        .p_statidx  = NSMPROC_MON,
        .p_name     = "MONITOR",
    },
[NSMPROC_UNMON] = {
        .p_proc     = NSMPROC_UNMON,
        .p_encode   = (kxdreproc_t)nsm_xdr_enc_unmon,
        .p_decode   = (kxdrdproc_t)nsm_xdr_dec_stat,
        .p_arglen   = SM_mon_id_sz,
        .p_replen   = SM_unmonres_sz,
        .p_statidx  = NSMPROC_UNMON,
        .p_name     = "UNMONITOR",
    },
};

static const struct rpc_version nsm_version1 = {
        .number     = 1,
        .nrprocs    = ARRAY_SIZE(nsm_procedures),
        .procs      = nsm_procedures
};

static const struct rpc_version *nsm_version[] = {
    [1] = &nsm_version1,
};

static struct rpc_stat      nsm_stats;

static const struct rpc_program nsm_program = {
        .name       = "statd",
        .number     = NSM_PROGRAM,
        .nrvers     = ARRAY_SIZE(nsm_version),
        .version    = nsm_version,
        .stats      = &nsm_stats
};