clntxdr.c

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/*
 * linux/fs/lockd/clntxdr.c
 *
 * XDR functions to encode/decode NLM version 3 RPC arguments and results.
 * NLM version 3 is backwards compatible with NLM versions 1 and 2.
 *
 * NLM client-side only.
 *
 * Copyright (C) 2010, Oracle.  All rights reserved.
 */

#include <linux/types.h>
#include <linux/sunrpc/xdr.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/stats.h>
#include <linux/lockd/lockd.h>

#define NLMDBG_FACILITY     NLMDBG_XDR

#if (NLMCLNT_OHSIZE > XDR_MAX_NETOBJ)
#  error "NLM host name cannot be larger than XDR_MAX_NETOBJ!"
#endif

/*
 * Declare the space requirements for NLM arguments and replies as
 * number of 32bit-words
 */
#define NLM_cookie_sz       (1+(NLM_MAXCOOKIELEN>>2))
#define NLM_caller_sz       (1+(NLMCLNT_OHSIZE>>2))
#define NLM_owner_sz        (1+(NLMCLNT_OHSIZE>>2))
#define NLM_fhandle_sz      (1+(NFS2_FHSIZE>>2))
#define NLM_lock_sz     (3+NLM_caller_sz+NLM_owner_sz+NLM_fhandle_sz)
#define NLM_holder_sz       (4+NLM_owner_sz)

#define NLM_testargs_sz     (NLM_cookie_sz+1+NLM_lock_sz)
#define NLM_lockargs_sz     (NLM_cookie_sz+4+NLM_lock_sz)
#define NLM_cancargs_sz     (NLM_cookie_sz+2+NLM_lock_sz)
#define NLM_unlockargs_sz   (NLM_cookie_sz+NLM_lock_sz)

#define NLM_testres_sz      (NLM_cookie_sz+1+NLM_holder_sz)
#define NLM_res_sz      (NLM_cookie_sz+1)
#define NLM_norep_sz        (0)


static s32 loff_t_to_s32(loff_t offset)
{
    s32 res;

    if (offset >= NLM_OFFSET_MAX)
        res = NLM_OFFSET_MAX;
    else if (offset <= -NLM_OFFSET_MAX)
        res = -NLM_OFFSET_MAX;
    else
        res = offset;
    return res;
}

static void nlm_compute_offsets(const struct nlm_lock *lock,
                u32 *l_offset, u32 *l_len)
{
    const struct file_lock *fl = &lock->fl;

    BUG_ON(fl->fl_start > NLM_OFFSET_MAX);
    BUG_ON(fl->fl_end > NLM_OFFSET_MAX &&
                fl->fl_end != OFFSET_MAX);

    *l_offset = loff_t_to_s32(fl->fl_start);
    if (fl->fl_end == OFFSET_MAX)
        *l_len = 0;
    else
        *l_len = loff_t_to_s32(fl->fl_end - fl->fl_start + 1);
}

/*
 * Handle decode buffer overflows out-of-line.
 */
static void print_overflow_msg(const char *func, const struct xdr_stream *xdr)
{
    dprintk("lockd: %s prematurely hit the end of our receive buffer. "
        "Remaining buffer length is %tu words.\n",
        func, xdr->end - xdr->p);
}


/*
 * Encode/decode NLMv3 basic data types
 *
 * Basic NLMv3 data types are not defined in an IETF standards
 * document.  X/Open has a description of these data types that
 * is useful.  See Chapter 10 of "Protocols for Interworking:
 * XNFS, Version 3W".
 *
 * Not all basic data types have their own encoding and decoding
 * functions.  For run-time efficiency, some data types are encoded
 * or decoded inline.
 */

static void encode_bool(struct xdr_stream *xdr, const int value)
{
    __be32 *p;

    p = xdr_reserve_space(xdr, 4);
    *p = value ? xdr_one : xdr_zero;
}

static void encode_int32(struct xdr_stream *xdr, const s32 value)
{
    __be32 *p;

    p = xdr_reserve_space(xdr, 4);
    *p = cpu_to_be32(value);
}

/*
 *  typedef opaque netobj<MAXNETOBJ_SZ>
 */
static void encode_netobj(struct xdr_stream *xdr,
              const u8 *data, const unsigned int length)
{
    __be32 *p;

    BUG_ON(length > XDR_MAX_NETOBJ);
    p = xdr_reserve_space(xdr, 4 + length);
    xdr_encode_opaque(p, data, length);
}

static int decode_netobj(struct xdr_stream *xdr,
             struct xdr_netobj *obj)
{
    u32 length;
    __be32 *p;

    p = xdr_inline_decode(xdr, 4);
    if (unlikely(p == NULL))
        goto out_overflow;
    length = be32_to_cpup(p++);
    if (unlikely(length > XDR_MAX_NETOBJ))
        goto out_size;
    obj->len = length;
    obj->data = (u8 *)p;
    return 0;
out_size:
    dprintk("NFS: returned netobj was too long: %u\n", length);
    return -EIO;
out_overflow:
    print_overflow_msg(__func__, xdr);
    return -EIO;
}

/*
 *  netobj cookie;
 */
static void encode_cookie(struct xdr_stream *xdr,
              const struct nlm_cookie *cookie)
{
    BUG_ON(cookie->len > NLM_MAXCOOKIELEN);
    encode_netobj(xdr, (u8 *)&cookie->data, cookie->len);
}

static int decode_cookie(struct xdr_stream *xdr,
             struct nlm_cookie *cookie)
{
    u32 length;
    __be32 *p;

    p = xdr_inline_decode(xdr, 4);
    if (unlikely(p == NULL))
        goto out_overflow;
    length = be32_to_cpup(p++);
    /* apparently HPUX can return empty cookies */
    if (length == 0)
        goto out_hpux;
    if (length > NLM_MAXCOOKIELEN)
        goto out_size;
    p = xdr_inline_decode(xdr, length);
    if (unlikely(p == NULL))
        goto out_overflow;
    cookie->len = length;
    memcpy(cookie->data, p, length);
    return 0;
out_hpux:
    cookie->len = 4;
    memset(cookie->data, 0, 4);
    return 0;
out_size:
    dprintk("NFS: returned cookie was too long: %u\n", length);
    return -EIO;
out_overflow:
    print_overflow_msg(__func__, xdr);
    return -EIO;
}

/*
 *  netobj fh;
 */
static void encode_fh(struct xdr_stream *xdr, const struct nfs_fh *fh)
{
    BUG_ON(fh->size != NFS2_FHSIZE);
    encode_netobj(xdr, (u8 *)&fh->data, NFS2_FHSIZE);
}

/*
 *  enum nlm_stats {
 *      LCK_GRANTED = 0,
 *      LCK_DENIED = 1,
 *      LCK_DENIED_NOLOCKS = 2,
 *      LCK_BLOCKED = 3,
 *      LCK_DENIED_GRACE_PERIOD = 4
 *  };
 *
 *
 *  struct nlm_stat {
 *      nlm_stats stat;
 *  };
 *
 * NB: we don't swap bytes for the NLM status values.  The upper
 * layers deal directly with the status value in network byte
 * order.
 */

static void encode_nlm_stat(struct xdr_stream *xdr,
                const __be32 stat)
{
    __be32 *p;

    WARN_ON_ONCE(be32_to_cpu(stat) > NLM_LCK_DENIED_GRACE_PERIOD);
    p = xdr_reserve_space(xdr, 4);
    *p = stat;
}

static int decode_nlm_stat(struct xdr_stream *xdr,
               __be32 *stat)
{
    __be32 *p;

    p = xdr_inline_decode(xdr, 4);
    if (unlikely(p == NULL))
        goto out_overflow;
    if (unlikely(ntohl(*p) > ntohl(nlm_lck_denied_grace_period)))
        goto out_enum;
    *stat = *p;
    return 0;
out_enum:
    dprintk("%s: server returned invalid nlm_stats value: %u\n",
        __func__, be32_to_cpup(p));
    return -EIO;
out_overflow:
    print_overflow_msg(__func__, xdr);
    return -EIO;
}

/*
 *  struct nlm_holder {
 *      bool exclusive;
 *      int uppid;
 *      netobj oh;
 *      unsigned l_offset;
 *      unsigned l_len;
 *  };
 */
static void encode_nlm_holder(struct xdr_stream *xdr,
                  const struct nlm_res *result)
{
    const struct nlm_lock *lock = &result->lock;
    u32 l_offset, l_len;
    __be32 *p;

    encode_bool(xdr, lock->fl.fl_type == F_RDLCK);
    encode_int32(xdr, lock->svid);
    encode_netobj(xdr, lock->oh.data, lock->oh.len);

    p = xdr_reserve_space(xdr, 4 + 4);
    nlm_compute_offsets(lock, &l_offset, &l_len);
    *p++ = cpu_to_be32(l_offset);
    *p   = cpu_to_be32(l_len);
}

static int decode_nlm_holder(struct xdr_stream *xdr, struct nlm_res *result)
{
    struct nlm_lock *lock = &result->lock;
    struct file_lock *fl = &lock->fl;
    u32 exclusive, l_offset, l_len;
    int error;
    __be32 *p;
    s32 end;

    memset(lock, 0, sizeof(*lock));
    locks_init_lock(fl);

    p = xdr_inline_decode(xdr, 4 + 4);
    if (unlikely(p == NULL))
        goto out_overflow;
    exclusive = be32_to_cpup(p++);
    lock->svid = be32_to_cpup(p);
    fl->fl_pid = (pid_t)lock->svid;

    error = decode_netobj(xdr, &lock->oh);
    if (unlikely(error))
        goto out;

    p = xdr_inline_decode(xdr, 4 + 4);
    if (unlikely(p == NULL))
        goto out_overflow;

    fl->fl_flags = FL_POSIX;
    fl->fl_type  = exclusive != 0 ? F_WRLCK : F_RDLCK;
    l_offset = be32_to_cpup(p++);
    l_len = be32_to_cpup(p);
    end = l_offset + l_len - 1;

    fl->fl_start = (loff_t)l_offset;
    if (l_len == 0 || end < 0)
        fl->fl_end = OFFSET_MAX;
    else
        fl->fl_end = (loff_t)end;
    error = 0;
out:
    return error;
out_overflow:
    print_overflow_msg(__func__, xdr);
    return -EIO;
}

/*
 *  string caller_name<LM_MAXSTRLEN>;
 */
static void encode_caller_name(struct xdr_stream *xdr, const char *name)
{
    /* NB: client-side does not set lock->len */
    u32 length = strlen(name);
    __be32 *p;

    BUG_ON(length > NLM_MAXSTRLEN);
    p = xdr_reserve_space(xdr, 4 + length);
    xdr_encode_opaque(p, name, length);
}

/*
 *  struct nlm_lock {
 *      string caller_name<LM_MAXSTRLEN>;
 *      netobj fh;
 *      netobj oh;
 *      int uppid;
 *      unsigned l_offset;
 *      unsigned l_len;
 *  };
 */
static void encode_nlm_lock(struct xdr_stream *xdr,
                const struct nlm_lock *lock)
{
    u32 l_offset, l_len;
    __be32 *p;

    encode_caller_name(xdr, lock->caller);
    encode_fh(xdr, &lock->fh);
    encode_netobj(xdr, lock->oh.data, lock->oh.len);

    p = xdr_reserve_space(xdr, 4 + 4 + 4);
    *p++ = cpu_to_be32(lock->svid);

    nlm_compute_offsets(lock, &l_offset, &l_len);
    *p++ = cpu_to_be32(l_offset);
    *p   = cpu_to_be32(l_len);
}


/*
 * NLMv3 XDR encode functions
 *
 * NLMv3 argument types are defined in Chapter 10 of The Open Group's
 * "Protocols for Interworking: XNFS, Version 3W".
 */

/*
 *  struct nlm_testargs {
 *      netobj cookie;
 *      bool exclusive;
 *      struct nlm_lock alock;
 *  };
 */
static void nlm_xdr_enc_testargs(struct rpc_rqst *req,
                 struct xdr_stream *xdr,
                 const struct nlm_args *args)
{
    const struct nlm_lock *lock = &args->lock;

    encode_cookie(xdr, &args->cookie);
    encode_bool(xdr, lock->fl.fl_type == F_WRLCK);
    encode_nlm_lock(xdr, lock);
}

/*
 *  struct nlm_lockargs {
 *      netobj cookie;
 *      bool block;
 *      bool exclusive;
 *      struct nlm_lock alock;
 *      bool reclaim;
 *      int state;
 *  };
 */
static void nlm_xdr_enc_lockargs(struct rpc_rqst *req,
                 struct xdr_stream *xdr,
                 const struct nlm_args *args)
{
    const struct nlm_lock *lock = &args->lock;

    encode_cookie(xdr, &args->cookie);
    encode_bool(xdr, args->block);
    encode_bool(xdr, lock->fl.fl_type == F_WRLCK);
    encode_nlm_lock(xdr, lock);
    encode_bool(xdr, args->reclaim);
    encode_int32(xdr, args->state);
}

/*
 *  struct nlm_cancargs {
 *      netobj cookie;
 *      bool block;
 *      bool exclusive;
 *      struct nlm_lock alock;
 *  };
 */
static void nlm_xdr_enc_cancargs(struct rpc_rqst *req,
                 struct xdr_stream *xdr,
                 const struct nlm_args *args)
{
    const struct nlm_lock *lock = &args->lock;

    encode_cookie(xdr, &args->cookie);
    encode_bool(xdr, args->block);
    encode_bool(xdr, lock->fl.fl_type == F_WRLCK);
    encode_nlm_lock(xdr, lock);
}

/*
 *  struct nlm_unlockargs {
 *      netobj cookie;
 *      struct nlm_lock alock;
 *  };
 */
static void nlm_xdr_enc_unlockargs(struct rpc_rqst *req,
                   struct xdr_stream *xdr,
                   const struct nlm_args *args)
{
    const struct nlm_lock *lock = &args->lock;

    encode_cookie(xdr, &args->cookie);
    encode_nlm_lock(xdr, lock);
}

/*
 *  struct nlm_res {
 *      netobj cookie;
 *      nlm_stat stat;
 *  };
 */
static void nlm_xdr_enc_res(struct rpc_rqst *req,
                struct xdr_stream *xdr,
                const struct nlm_res *result)
{
    encode_cookie(xdr, &result->cookie);
    encode_nlm_stat(xdr, result->status);
}

/*
 *  union nlm_testrply switch (nlm_stats stat) {
 *  case LCK_DENIED:
 *      struct nlm_holder holder;
 *  default:
 *      void;
 *  };
 *
 *  struct nlm_testres {
 *      netobj cookie;
 *      nlm_testrply test_stat;
 *  };
 */
static void encode_nlm_testrply(struct xdr_stream *xdr,
                const struct nlm_res *result)
{
    if (result->status == nlm_lck_denied)
        encode_nlm_holder(xdr, result);
}

static void nlm_xdr_enc_testres(struct rpc_rqst *req,
                struct xdr_stream *xdr,
                const struct nlm_res *result)
{
    encode_cookie(xdr, &result->cookie);
    encode_nlm_stat(xdr, result->status);
    encode_nlm_testrply(xdr, result);
}


/*
 * NLMv3 XDR decode functions
 *
 * NLMv3 result types are defined in Chapter 10 of The Open Group's
 * "Protocols for Interworking: XNFS, Version 3W".
 */

/*
 *  union nlm_testrply switch (nlm_stats stat) {
 *  case LCK_DENIED:
 *      struct nlm_holder holder;
 *  default:
 *      void;
 *  };
 *
 *  struct nlm_testres {
 *      netobj cookie;
 *      nlm_testrply test_stat;
 *  };
 */
static int decode_nlm_testrply(struct xdr_stream *xdr,
                   struct nlm_res *result)
{
    int error;

    error = decode_nlm_stat(xdr, &result->status);
    if (unlikely(error))
        goto out;
    if (result->status == nlm_lck_denied)
        error = decode_nlm_holder(xdr, result);
out:
    return error;
}

static int nlm_xdr_dec_testres(struct rpc_rqst *req,
                   struct xdr_stream *xdr,
                   struct nlm_res *result)
{
    int error;

    error = decode_cookie(xdr, &result->cookie);
    if (unlikely(error))
        goto out;
    error = decode_nlm_testrply(xdr, result);
out:
    return error;
}

/*
 *  struct nlm_res {
 *      netobj cookie;
 *      nlm_stat stat;
 *  };
 */
static int nlm_xdr_dec_res(struct rpc_rqst *req,
               struct xdr_stream *xdr,
               struct nlm_res *result)
{
    int error;

    error = decode_cookie(xdr, &result->cookie);
    if (unlikely(error))
        goto out;
    error = decode_nlm_stat(xdr, &result->status);
out:
    return error;
}


/*
 * For NLM, a void procedure really returns nothing
 */
#define nlm_xdr_dec_norep   NULL

#define PROC(proc, argtype, restype)    \
[NLMPROC_##proc] = {                            \
    .p_proc      = NLMPROC_##proc,                  \
    .p_encode    = (kxdreproc_t)nlm_xdr_enc_##argtype,      \
    .p_decode    = (kxdrdproc_t)nlm_xdr_dec_##restype,      \
    .p_arglen    = NLM_##argtype##_sz,              \
    .p_replen    = NLM_##restype##_sz,              \
    .p_statidx   = NLMPROC_##proc,                  \
    .p_name      = #proc,                       \
    }

static struct rpc_procinfo  nlm_procedures[] = {
    PROC(TEST,      testargs,   testres),
    PROC(LOCK,      lockargs,   res),
    PROC(CANCEL,        cancargs,   res),
    PROC(UNLOCK,        unlockargs, res),
    PROC(GRANTED,       testargs,   res),
    PROC(TEST_MSG,      testargs,   norep),
    PROC(LOCK_MSG,      lockargs,   norep),
    PROC(CANCEL_MSG,    cancargs,   norep),
    PROC(UNLOCK_MSG,    unlockargs, norep),
    PROC(GRANTED_MSG,   testargs,   norep),
    PROC(TEST_RES,      testres,    norep),
    PROC(LOCK_RES,      res,        norep),
    PROC(CANCEL_RES,    res,        norep),
    PROC(UNLOCK_RES,    res,        norep),
    PROC(GRANTED_RES,   res,        norep),
};

static const struct rpc_version nlm_version1 = {
        .number     = 1,
        .nrprocs    = ARRAY_SIZE(nlm_procedures),
        .procs      = nlm_procedures,
};

static const struct rpc_version nlm_version3 = {
        .number     = 3,
        .nrprocs    = ARRAY_SIZE(nlm_procedures),
        .procs      = nlm_procedures,
};

static const struct rpc_version *nlm_versions[] = {
    [1] = &nlm_version1,
    [3] = &nlm_version3,
#ifdef CONFIG_LOCKD_V4
    [4] = &nlm_version4,
#endif
};

static struct rpc_stat      nlm_rpc_stats;

const struct rpc_program    nlm_program = {
        .name       = "lockd",
        .number     = NLM_PROGRAM,
        .nrvers     = ARRAY_SIZE(nlm_versions),
        .version    = nlm_versions,
        .stats      = &nlm_rpc_stats,
};