glibc/sunrpc/svc_unix.c

/*
 * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
 * unrestricted use provided that this legend is included on all tape
 * media and as a part of the software program in whole or part.  Users
 * may copy or modify Sun RPC without charge, but are not authorized
 * to license or distribute it to anyone else except as part of a product or
 * program developed by the user.
 *
 * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
 * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
 *
 * Sun RPC is provided with no support and without any obligation on the
 * part of Sun Microsystems, Inc. to assist in its use, correction,
 * modification or enhancement.
 *
 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
 * OR ANY PART THEREOF.
 *
 * In no event will Sun Microsystems, Inc. be liable for any lost revenue
 * or profits or other special, indirect and consequential damages, even if
 * Sun has been advised of the possibility of such damages.
 *
 * Sun Microsystems, Inc.
 * 2550 Garcia Avenue
 * Mountain View, California  94043
 */

/*
 * svc_unix.c, Server side for TCP/IP based RPC.
 *
 * Copyright (C) 1984, Sun Microsystems, Inc.
 *
 * Actually implements two flavors of transporter -
 * a unix rendezvouser (a listener and connection establisher)
 * and a record/unix stream.
 */

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <rpc/rpc.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <sys/poll.h>
#include <errno.h>
#include <stdlib.h>

/*
 * Ops vector for AF_UNIX based rpc service handle
 */
static bool_t svcunix_recv (SVCXPRT *, struct rpc_msg *);
static enum xprt_stat svcunix_stat (SVCXPRT *);
static bool_t svcunix_getargs (SVCXPRT *, xdrproc_t, caddr_t);
static bool_t svcunix_reply (SVCXPRT *, struct rpc_msg *);
static bool_t svcunix_freeargs (SVCXPRT *, xdrproc_t, caddr_t);
static void svcunix_destroy (SVCXPRT *);

static const struct xp_ops svcunix_op =
{
  svcunix_recv,
  svcunix_stat,
  svcunix_getargs,
  svcunix_reply,
  svcunix_freeargs,
  svcunix_destroy
};

/*
 * Ops vector for AF_UNIX rendezvous handler
 */
static bool_t rendezvous_request (SVCXPRT *, struct rpc_msg *);
static enum xprt_stat rendezvous_stat (SVCXPRT *);

static const struct xp_ops svcunix_rendezvous_op =
{
  rendezvous_request,
  rendezvous_stat,
  (bool_t (*) (SVCXPRT *, xdrproc_t, caddr_t)) abort,
  (bool_t (*) (SVCXPRT *, struct rpc_msg *)) abort,
  (bool_t (*) (SVCXPRT *, xdrproc_t, caddr_t)) abort,
  svcunix_destroy
};

static int readunix (char*, char *, int);
static int writeunix (char *, char *, int);
static SVCXPRT *makefd_xprt (int, u_int, u_int) internal_function;

struct unix_rendezvous {        /* kept in xprt->xp_p1 */
  u_int sendsize;
  u_int recvsize;
};

struct unix_conn {		/* kept in xprt->xp_p1 */
  enum xprt_stat strm_stat;
  u_long x_id;
  XDR xdrs;
  char verf_body[MAX_AUTH_BYTES];
};

/*
 * Usage:
 *      xprt = svcunix_create(sock, send_buf_size, recv_buf_size);
 *
 * Creates, registers, and returns a (rpc) unix based transporter.
 * Once *xprt is initialized, it is registered as a transporter
 * see (svc.h, xprt_register).  This routine returns
 * a NULL if a problem occurred.
 *
 * If sock<0 then a socket is created, else sock is used.
 * If the socket, sock is not bound to a port then svcunix_create
 * binds it to an arbitrary port.  The routine then starts a unix
 * listener on the socket's associated port.  In any (successful) case,
 * xprt->xp_sock is the registered socket number and xprt->xp_port is the
 * associated port number.
 *
 * Since unix streams do buffered io similar to stdio, the caller can specify
 * how big the send and receive buffers are via the second and third parms;
 * 0 => use the system default.
 */
SVCXPRT *
svcunix_create (int sock, u_int sendsize, u_int recvsize, char *path)
{
  bool_t madesock = FALSE;
  SVCXPRT *xprt;
  struct unix_rendezvous *r;
  struct sockaddr_un addr;
  socklen_t len = sizeof (struct sockaddr_in);

  if (sock == RPC_ANYSOCK)
    {
      if ((sock = __socket (AF_UNIX, SOCK_STREAM, 0)) < 0)
	{
	  perror (_("svc_unix.c - AF_UNIX socket creation problem"));
	  return (SVCXPRT *) NULL;
	}
      madesock = TRUE;
    }
  memset (&addr, '\0', sizeof (addr));
  addr.sun_family = AF_UNIX;
  len = strlen (path) + 1;
  memcpy (addr.sun_path, path, len);
  len += sizeof (addr.sun_family);

  bind (sock, (struct sockaddr *) &addr, len);

  if (getsockname (sock, (struct sockaddr *) &addr, &len) != 0
      || listen (sock, 2) != 0)
    {
      perror (_("svc_unix.c - cannot getsockname or listen"));
      if (madesock)
	__close (sock);
      return (SVCXPRT *) NULL;
    }

  r = (struct unix_rendezvous *) mem_alloc (sizeof (*r));
  if (r == NULL)
    {
      fputs (_("svcunix_create: out of memory\n"), stderr);
      return NULL;
    }
  r->sendsize = sendsize;
  r->recvsize = recvsize;
  xprt = (SVCXPRT *) mem_alloc (sizeof (SVCXPRT));
  if (xprt == NULL)
    {
      fputs (_("svcunix_create: out of memory\n"), stderr);
      return NULL;
    }
  xprt->xp_p2 = NULL;
  xprt->xp_p1 = (caddr_t) r;
  xprt->xp_verf = _null_auth;
  xprt->xp_ops = &svcunix_rendezvous_op;
  xprt->xp_port = -1;
  xprt->xp_sock = sock;
  xprt_register (xprt);
  return xprt;
}

/*
 * Like svunix_create(), except the routine takes any *open* UNIX file
 * descriptor as its first input.
 */
SVCXPRT *
svcunixfd_create (int fd, u_int sendsize, u_int recvsize)
{
  return makefd_xprt (fd, sendsize, recvsize);
}

static SVCXPRT *
internal_function
makefd_xprt (int fd, u_int sendsize, u_int recvsize)
{
  SVCXPRT *xprt;
  struct unix_conn *cd;

  xprt = (SVCXPRT *) mem_alloc (sizeof (SVCXPRT));
  if (xprt == (SVCXPRT *) NULL)
    {
      (void) fputs (_("svc_unix: makefd_xprt: out of memory\n"), stderr);
      goto done;
    }
  cd = (struct unix_conn *) mem_alloc (sizeof (struct unix_conn));
  if (cd == (struct unix_conn *) NULL)
    {
      (void) fputs (_("svc_unix: makefd_xprt: out of memory\n"), stderr);
      mem_free ((char *) xprt, sizeof (SVCXPRT));
      xprt = (SVCXPRT *) NULL;
      goto done;
    }
  cd->strm_stat = XPRT_IDLE;
  xdrrec_create (&(cd->xdrs), sendsize, recvsize,
		 (caddr_t) xprt, readunix, writeunix);
  xprt->xp_p2 = NULL;
  xprt->xp_p1 = (caddr_t) cd;
  xprt->xp_verf.oa_base = cd->verf_body;
  xprt->xp_addrlen = 0;
  xprt->xp_ops = &svcunix_op;	/* truly deals with calls */
  xprt->xp_port = 0;		/* this is a connection, not a rendezvouser */
  xprt->xp_sock = fd;
  xprt_register (xprt);
done:
  return xprt;
}

static bool_t
rendezvous_request (SVCXPRT *xprt, struct rpc_msg *errmsg)
{
  int sock;
  struct unix_rendezvous *r;
  struct sockaddr_un addr;
  struct sockaddr_in in_addr;
  socklen_t len;

  r = (struct unix_rendezvous *) xprt->xp_p1;
again:
  len = sizeof (struct sockaddr_un);
  if ((sock = accept (xprt->xp_sock, (struct sockaddr *) &addr, &len)) < 0)
    {
      if (errno == EINTR)
	goto again;
      return FALSE;
    }
  /*
   * make a new transporter (re-uses xprt)
   */
  memset (&in_addr, '\0', sizeof (in_addr));
  in_addr.sin_family = AF_UNIX;
  xprt = makefd_xprt (sock, r->sendsize, r->recvsize);
  xprt->xp_raddr = in_addr;
  xprt->xp_addrlen = len;
  return FALSE;		/* there is never an rpc msg to be processed */
}

static enum xprt_stat
rendezvous_stat (SVCXPRT *xprt)
{
  return XPRT_IDLE;
}

static void
svcunix_destroy (SVCXPRT *xprt)
{
  struct unix_conn *cd = (struct unix_conn *) xprt->xp_p1;

  xprt_unregister (xprt);
  __close (xprt->xp_sock);
  if (xprt->xp_port != 0)
    {
      /* a rendezvouser socket */
      xprt->xp_port = 0;
    }
  else
    {
      /* an actual connection socket */
      XDR_DESTROY (&(cd->xdrs));
    }
  mem_free ((caddr_t) cd, sizeof (struct unix_conn));
  mem_free ((caddr_t) xprt, sizeof (SVCXPRT));
}

struct cmessage {
  struct cmsghdr cmsg;
  struct ucred cmcred;
};

/* XXX This is not thread safe, but since the main functions in svc.c
   and the rpcgen generated *_svc functions for the daemon are also not
   thread safe and uses static global variables, it doesn't matter. */
static struct cmessage cm;

static int
__msgread (int sock, void *buf, size_t cnt)
{
  struct iovec iov[1];
  struct msghdr msg;
  int on = 1;

  iov[0].iov_base = buf;
  iov[0].iov_len = cnt;

  msg.msg_iov = iov;
  msg.msg_iovlen = 1;
  msg.msg_name = NULL;
  msg.msg_namelen = 0;
  msg.msg_control = (caddr_t) &cm;
  msg.msg_controllen = sizeof (struct cmessage);
  msg.msg_flags = 0;

#ifdef SO_PASSCRED
  if (setsockopt (sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof (on)))
    return -1;
#endif

  return recvmsg (sock, &msg, 0);
}

static int
__msgwrite (int sock, void *buf, size_t cnt)
{
#ifndef SCM_CREDENTIALS
  /* We cannot implement this reliably.  */
  __set_errno (ENOSYS);
  return -1;
#else
  struct iovec iov[1];
  struct msghdr msg;

  iov[0].iov_base = buf;
  iov[0].iov_len = cnt;

  cm.cmsg.cmsg_type = SCM_CREDENTIALS;
  cm.cmsg.cmsg_level = SOL_SOCKET;
  cm.cmsg.cmsg_len = sizeof (struct cmessage);
  /* XXX I'm not sure, if we really should use gete?id(), or get?id().
     It would be much better, if the kernel could pass both to the
     client. */
  cm.cmcred.pid = __getpid ();
  cm.cmcred.uid = __geteuid ();
  cm.cmcred.gid = __getegid ();

  msg.msg_iov = iov;
  msg.msg_iovlen = 1;
  msg.msg_name = NULL;
  msg.msg_namelen = 0;
  msg.msg_control = (caddr_t) &cm;
  msg.msg_controllen = sizeof (struct cmessage);
  msg.msg_flags = 0;

  return sendmsg (sock, &msg, 0);
#endif
}

/*
 * reads data from the unix connection.
 * any error is fatal and the connection is closed.
 * (And a read of zero bytes is a half closed stream => error.)
 */
static int
readunix (char *xprtptr, char *buf, int len)
{
  SVCXPRT *xprt = (SVCXPRT *) xprtptr;
  int sock = xprt->xp_sock;
  int milliseconds = 35 * 1000;
  struct pollfd pollfd;

  do
    {
      pollfd.fd = sock;
      pollfd.events = POLLIN;
      switch (__poll (&pollfd, 1, milliseconds))
	{
	case -1:
	  if (errno == EINTR)
	    continue;
	  /*FALLTHROUGH*/
	case 0:
	  goto fatal_err;
	default:
	  break;
	}
    }
  while ((pollfd.revents & POLLIN) == 0);

  if ((len = __msgread (sock, buf, len)) > 0)
    return len;

 fatal_err:
  ((struct unix_conn *) (xprt->xp_p1))->strm_stat = XPRT_DIED;
  return -1;
}

/*
 * writes data to the unix connection.
 * Any error is fatal and the connection is closed.
 */
static int
writeunix (char *xprtptr, char * buf, int len)
{
  SVCXPRT *xprt = (SVCXPRT *) xprtptr;
  int i, cnt;

  for (cnt = len; cnt > 0; cnt -= i, buf += i)
    {
      if ((i = __msgwrite (xprt->xp_sock, buf, cnt)) < 0)
	{
	  ((struct unix_conn *) (xprt->xp_p1))->strm_stat = XPRT_DIED;
	  return -1;
	}
    }
  return len;
}

static enum xprt_stat
svcunix_stat (SVCXPRT *xprt)
{
  struct unix_conn *cd =
  (struct unix_conn *) (xprt->xp_p1);

  if (cd->strm_stat == XPRT_DIED)
    return XPRT_DIED;
  if (!xdrrec_eof (&(cd->xdrs)))
    return XPRT_MOREREQS;
  return XPRT_IDLE;
}

static bool_t
svcunix_recv (SVCXPRT *xprt, struct rpc_msg *msg)
{
  struct unix_conn *cd = (struct unix_conn *) (xprt->xp_p1);
  XDR *xdrs = &(cd->xdrs);

  xdrs->x_op = XDR_DECODE;
  xdrrec_skiprecord (xdrs);
  if (xdr_callmsg (xdrs, msg))
    {
      cd->x_id = msg->rm_xid;
      /* set up verifiers */
      msg->rm_call.cb_verf.oa_flavor = AUTH_UNIX;
      msg->rm_call.cb_verf.oa_base = (caddr_t) &cm;
      msg->rm_call.cb_verf.oa_length = sizeof (cm);
      return TRUE;
    }
  cd->strm_stat = XPRT_DIED;	/* XXXX */
  return FALSE;
}

static bool_t
svcunix_getargs (SVCXPRT *xprt, xdrproc_t xdr_args, caddr_t args_ptr)
{
  return (*xdr_args) (&(((struct unix_conn *) (xprt->xp_p1))->xdrs),
		      args_ptr);
}

static bool_t
svcunix_freeargs (SVCXPRT *xprt, xdrproc_t xdr_args, caddr_t args_ptr)
{
  XDR *xdrs = &(((struct unix_conn *) (xprt->xp_p1))->xdrs);

  xdrs->x_op = XDR_FREE;
  return (*xdr_args) (xdrs, args_ptr);
}

static bool_t
svcunix_reply (SVCXPRT *xprt, struct rpc_msg *msg)
{
  struct unix_conn *cd = (struct unix_conn *) (xprt->xp_p1);
  XDR *xdrs = &(cd->xdrs);
  bool_t stat;

  xdrs->x_op = XDR_ENCODE;
  msg->rm_xid = cd->x_id;
  stat = xdr_replymsg (xdrs, msg);
  (void) xdrrec_endofrecord (xdrs, TRUE);
  return stat;
}