/*
* OpenVPN -- An application to securely tunnel IP networks
* over a single UDP port, with support for SSL/TLS-based
* session authentication and key exchange,
* packet encryption, packet authentication, and
* packet compression.
*
* Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program (see the file COPYING included with this
* distribution); if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "syshead.h"
#if PORT_SHARE
#include "event.h"
#include "socket.h"
#include "fdmisc.h"
#include "crypto.h"
#include "ps.h"
#include "memdbg.h"
struct port_share *port_share = NULL; /* GLOBAL */
/* size of i/o buffers */
#define PROXY_CONNECTION_BUFFER_SIZE 1500
/* Command codes for foreground -> background communication */
#define COMMAND_REDIRECT 10
#define COMMAND_EXIT 11
/* Response codes for background -> foreground communication */
#define RESPONSE_INIT_SUCCEEDED 20
#define RESPONSE_INIT_FAILED 21
/*
* Return values for proxy_connection_io functions
*/
#define IOSTAT_EAGAIN_ON_READ 0 /* recv returned EAGAIN */
#define IOSTAT_EAGAIN_ON_WRITE 1 /* send returned EAGAIN */
#define IOSTAT_READ_ERROR 2 /* the other end of our read socket (pc) was closed */
#define IOSTAT_WRITE_ERROR 3 /* the other end of our write socket (pc->counterpart) was closed */
#define IOSTAT_GOOD 4 /* nothing to report */
/*
* A foreign (non-OpenVPN) connection we are proxying,
* usually HTTPS
*/
struct proxy_connection {
bool defined;
struct proxy_connection *next;
struct proxy_connection *counterpart;
struct buffer buf;
bool buffer_initial;
int rwflags;
int sd;
};
#if 0
static const char *
headc (const struct buffer *buf)
{
static char foo[16];
strncpy (foo, BSTR(buf), 15);
foo[15] = 0;
return foo;
}
#endif
static inline void
close_socket_if_defined (const socket_descriptor_t sd)
{
if (socket_defined (sd))
openvpn_close_socket (sd);
}
/*
* Close most of parent's fds.
* Keep stdin/stdout/stderr, plus one
* other fd which is presumed to be
* our pipe back to parent.
* Admittedly, a bit of a kludge,
* but posix doesn't give us a kind
* of FD_CLOEXEC which will stop
* fds from crossing a fork().
*/
static void
close_fds_except (int keep)
{
socket_descriptor_t i;
closelog ();
for (i = 3; i <= 100; ++i)
{
if (i != keep)
openvpn_close_socket (i);
}
}
/*
* Usually we ignore signals, because our parent will
* deal with them.
*/
static void
set_signals (void)
{
signal (SIGTERM, SIG_DFL);
signal (SIGINT, SIG_IGN);
signal (SIGHUP, SIG_IGN);
signal (SIGUSR1, SIG_IGN);
signal (SIGUSR2, SIG_IGN);
signal (SIGPIPE, SIG_IGN);
}
/*
* Socket read/write functions.
*/
static int
recv_control (const socket_descriptor_t fd)
{
unsigned char c;
const ssize_t size = read (fd, &c, sizeof (c));
if (size == sizeof (c))
return c;
else
{
return -1;
}
}
static int
send_control (const socket_descriptor_t fd, int code)
{
unsigned char c = (unsigned char) code;
const ssize_t size = write (fd, &c, sizeof (c));
if (size == sizeof (c))
return (int) size;
else
return -1;
}
static int
cmsg_size ()
{
return CMSG_SPACE(sizeof(socket_descriptor_t));
}
/*
* Send a command (char), data (head), and a file descriptor (sd_send) to a local process
* over unix socket sd. Unfortunately, there's no portable way to send file descriptors
* to other processes, so this code, as well as its analog (control_message_from_parent below),
* is Linux-specific. This function runs in the context of the main process and is used to
* send commands, data, and file descriptors to the background process.
*/
static void
port_share_sendmsg (const socket_descriptor_t sd,
const char command,
const struct buffer *head,
const socket_descriptor_t sd_send)
{
if (socket_defined (sd))
{
struct msghdr mesg;
struct cmsghdr* h;
struct iovec iov[2];
socket_descriptor_t sd_null[2] = { SOCKET_UNDEFINED, SOCKET_UNDEFINED };
char cmd;
ssize_t status;
dmsg (D_PS_PROXY_DEBUG, "PORT SHARE: sendmsg sd=%d len=%d",
(int)sd_send,
head ? BLEN(head) : -1);
CLEAR (mesg);
cmd = command;
iov[0].iov_base = &cmd;
iov[0].iov_len = sizeof (cmd);
mesg.msg_iovlen = 1;
if (head)
{
iov[1].iov_base = BPTR (head);
iov[1].iov_len = BLEN (head);
mesg.msg_iovlen = 2;
}
mesg.msg_iov = iov;
mesg.msg_controllen = cmsg_size ();
mesg.msg_control = (char *) malloc (mesg.msg_controllen);
check_malloc_return (mesg.msg_control);
mesg.msg_flags = 0;
h = CMSG_FIRSTHDR(&mesg);
h->cmsg_level = SOL_SOCKET;
h->cmsg_type = SCM_RIGHTS;
h->cmsg_len = CMSG_LEN(sizeof(socket_descriptor_t));
if (socket_defined (sd_send))
{
*((socket_descriptor_t*)CMSG_DATA(h)) = sd_send;
}
else
{
socketpair (PF_UNIX, SOCK_DGRAM, 0, sd_null);
*((socket_descriptor_t*)CMSG_DATA(h)) = sd_null[0];
}
status = sendmsg (sd, &mesg, MSG_NOSIGNAL);
if (status == -1)
msg (M_WARN, "PORT SHARE: sendmsg failed (unable to communicate with background process)");
close_socket_if_defined (sd_null[0]);
close_socket_if_defined (sd_null[1]);
free (mesg.msg_control);
}
}
static int
pc_list_len (struct proxy_connection *pc)
{
int count = 0;
while (pc)
{
++count;
pc = pc->next;
}
return count;
}
static void
proxy_entry_close_sd (struct proxy_connection *pc, struct event_set *es)
{
if (pc->defined && socket_defined (pc->sd))
{
dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: delete sd=%d", (int)pc->sd);
if (es)
event_del (es, pc->sd);
openvpn_close_socket (pc->sd);
pc->sd = SOCKET_UNDEFINED;
}
}
/*
* Mark a proxy entry and its counterpart for close.
*/
static void
proxy_entry_mark_for_close (struct proxy_connection *pc, struct event_set *es)
{
if (pc->defined)
{
struct proxy_connection *cp = pc->counterpart;
proxy_entry_close_sd (pc, es);
free_buf (&pc->buf);
pc->buffer_initial = false;
pc->rwflags = 0;
pc->defined = false;
if (cp && cp->defined && cp->counterpart == pc)
proxy_entry_mark_for_close (cp, es);
}
}
/*
* Run through the proxy entry list and delete all entries marked
* for close.
*/
static void
proxy_list_housekeeping (struct proxy_connection **list)
{
if (list)
{
struct proxy_connection *prev = NULL;
struct proxy_connection *pc = *list;
while (pc)
{
struct proxy_connection *next = pc->next;
if (!pc->defined)
{
free (pc);
if (prev)
prev->next = next;
else
*list = next;
}
else
prev = pc;
pc = next;
}
}
}
/*
* Cleanup function, on proxy process exit.
*/
static void
proxy_list_close (struct proxy_connection **list)
{
if (list)
{
struct proxy_connection *pc = *list;
while (pc)
{
proxy_entry_mark_for_close (pc, NULL);
pc = pc->next;
}
proxy_list_housekeeping (list);
}
}
static void
sock_addr_set (struct openvpn_sockaddr *osaddr,
const in_addr_t addr,
const int port)
{
CLEAR (*osaddr);
osaddr->sa.sin_family = AF_INET;
osaddr->sa.sin_addr.s_addr = htonl (addr);
osaddr->sa.sin_port = htons (port);
}
static inline void
proxy_connection_io_requeue (struct proxy_connection *pc, const int rwflags_new, struct event_set *es)
{
if (socket_defined (pc->sd) && pc->rwflags != rwflags_new)
{
/*dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: requeue[%d] rwflags=%d", (int)pc->sd, rwflags_new);*/
event_ctl (es, pc->sd, rwflags_new, (void*)pc);
pc->rwflags = rwflags_new;
}
}
/*
* Create a new pair of proxy_connection entries, one for each
* socket file descriptor involved in the proxy. We are given
* the client fd, and we should derive our own server fd by connecting
* to the server given by server_addr/server_port. Return true
* on success and false on failure to connect to server.
*/
static bool
proxy_entry_new (struct proxy_connection **list,
struct event_set *es,
const in_addr_t server_addr,
const int server_port,
const socket_descriptor_t sd_client,
struct buffer *initial_data)
{
struct openvpn_sockaddr osaddr;
socket_descriptor_t sd_server;
int status;
struct proxy_connection *pc;
struct proxy_connection *cp;
/* connect to port share server */
sock_addr_set (&osaddr, server_addr, server_port);
sd_server = create_socket_tcp ();
status = openvpn_connect (sd_server, &osaddr, 5, NULL);
if (status)
{
msg (M_WARN, "PORT SHARE PROXY: connect to port-share server failed");
openvpn_close_socket (sd_server);
return false;
}
dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: connect to port-share server succeeded");
set_nonblock (sd_client);
set_nonblock (sd_server);
/* allocate 2 new proxy_connection objects */
ALLOC_OBJ_CLEAR (pc, struct proxy_connection);
ALLOC_OBJ_CLEAR (cp, struct proxy_connection);
/* client object */
pc->defined = true;
pc->next = cp;
pc->counterpart = cp;
pc->buf = *initial_data;
pc->buffer_initial = true;
pc->rwflags = EVENT_UNDEF;
pc->sd = sd_client;
/* server object */
cp->defined = true;
cp->next = *list;
cp->counterpart = pc;
cp->buf = alloc_buf (PROXY_CONNECTION_BUFFER_SIZE);
cp->buffer_initial = false;
cp->rwflags = EVENT_UNDEF;
cp->sd = sd_server;
/* add to list */
*list = pc;
dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: NEW CONNECTION [c=%d s=%d]", (int)sd_client, (int)sd_server);
/* set initial i/o states */
proxy_connection_io_requeue (pc, EVENT_READ, es);
proxy_connection_io_requeue (cp, EVENT_READ|EVENT_WRITE, es);
return true;
}
/*
* This function runs in the context of the background proxy process.
* Receive a control message from the parent (sent by the port_share_sendmsg
* function above) and act on it. Return false if the proxy process should
* exit, true otherwise.
*/
static bool
control_message_from_parent (const socket_descriptor_t sd_control,
struct proxy_connection **list,
struct event_set *es,
const in_addr_t server_addr,
const int server_port)
{
struct buffer buf = alloc_buf (PROXY_CONNECTION_BUFFER_SIZE);
struct msghdr mesg;
struct cmsghdr* h;
struct iovec iov[2];
char command = 0;
ssize_t status;
int ret = true;
CLEAR (mesg);
iov[0].iov_base = &command;
iov[0].iov_len = sizeof (command);
iov[1].iov_base = BPTR (&buf);
iov[1].iov_len = BCAP (&buf);
mesg.msg_iov = iov;
mesg.msg_iovlen = 2;
mesg.msg_controllen = cmsg_size ();
mesg.msg_control = (char *) malloc (mesg.msg_controllen);
check_malloc_return (mesg.msg_control);
mesg.msg_flags = 0;
h = CMSG_FIRSTHDR(&mesg);
h->cmsg_len = CMSG_LEN(sizeof(socket_descriptor_t));
h->cmsg_level = SOL_SOCKET;
h->cmsg_type = SCM_RIGHTS;
*((socket_descriptor_t*)CMSG_DATA(h)) = SOCKET_UNDEFINED;
status = recvmsg (sd_control, &mesg, MSG_NOSIGNAL);
if (status != -1)
{
if ( h == NULL
|| h->cmsg_len != CMSG_LEN(sizeof(socket_descriptor_t))
|| h->cmsg_level != SOL_SOCKET
|| h->cmsg_type != SCM_RIGHTS )
{
ret = false;
}
else
{
const socket_descriptor_t received_fd = *((socket_descriptor_t*)CMSG_DATA(h));
dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: RECEIVED sd=%d", (int)received_fd);
if (status >= 2 && command == COMMAND_REDIRECT)
{
buf.len = status - 1;
if (proxy_entry_new (list,
es,
server_addr,
server_port,
received_fd,
&buf))
{
CLEAR (buf); /* we gave the buffer to proxy_entry_new */
}
else
{
openvpn_close_socket (received_fd);
}
}
else if (status >= 1 && command == COMMAND_EXIT)
{
dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: RECEIVED COMMAND_EXIT");
openvpn_close_socket (received_fd); /* null socket */
ret = false;
}
}
}
free (mesg.msg_control);
free_buf (&buf);
return ret;
}
static int
proxy_connection_io_recv (struct proxy_connection *pc)
{
/* recv data from socket */
const int status = recv (pc->sd, BPTR(&pc->buf), BCAP(&pc->buf), MSG_NOSIGNAL);
if (status < 0)
{
return (errno == EAGAIN) ? IOSTAT_EAGAIN_ON_READ : IOSTAT_READ_ERROR;
}
else
{
if (!status)
return IOSTAT_READ_ERROR;
pc->buf.len = status;
}
return IOSTAT_GOOD;
}
static int
proxy_connection_io_send (struct proxy_connection *pc, int *bytes_sent)
{
const socket_descriptor_t sd = pc->counterpart->sd;
const int status = send (sd, BPTR(&pc->buf), BLEN(&pc->buf), MSG_NOSIGNAL);
if (status < 0)
{
const int e = errno;
return (e == EAGAIN) ? IOSTAT_EAGAIN_ON_WRITE : IOSTAT_WRITE_ERROR;
}
else
{
*bytes_sent += status;
if (status != pc->buf.len)
{
dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: partial write[%d], tried=%d got=%d", (int)sd, pc->buf.len, status);
buf_advance (&pc->buf, status);
return IOSTAT_EAGAIN_ON_WRITE;
}
else
{
/*dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: wrote[%d] %d", (int)sd, status);*/
pc->buf.len = 0;
pc->buf.offset = 0;
}
}
/* realloc send buffer after initial send */
if (pc->buffer_initial)
{
free_buf (&pc->buf);
pc->buf = alloc_buf (PROXY_CONNECTION_BUFFER_SIZE);
pc->buffer_initial = false;
}
return IOSTAT_GOOD;
}
/*
* Forward data from pc to pc->counterpart.
*/
static int
proxy_connection_io_xfer (struct proxy_connection *pc, const int max_transfer)
{
int transferred = 0;
while (transferred < max_transfer)
{
if (!BLEN (&pc->buf))
{
const int status = proxy_connection_io_recv (pc);
if (status != IOSTAT_GOOD)
return status;
}
if (BLEN (&pc->buf))
{
const int status = proxy_connection_io_send (pc, &transferred);
if (status != IOSTAT_GOOD)
return status;
}
}
return IOSTAT_EAGAIN_ON_READ;
}
/*
* Decide how the receipt of an EAGAIN status should affect our next IO queueing.
*/
static bool
proxy_connection_io_status (const int status, int *rwflags_pc, int *rwflags_cp)
{
switch (status)
{
case IOSTAT_EAGAIN_ON_READ:
*rwflags_pc |= EVENT_READ;
*rwflags_cp &= ~EVENT_WRITE;
return true;
case IOSTAT_EAGAIN_ON_WRITE:
*rwflags_pc &= ~EVENT_READ;
*rwflags_cp |= EVENT_WRITE;
return true;
case IOSTAT_READ_ERROR:
return false;
case IOSTAT_WRITE_ERROR:
return false;
default:
msg (M_FATAL, "PORT SHARE PROXY: unexpected status=%d", status);
}
return false; /* NOTREACHED */
}
/*
* Dispatch function for forwarding data between the two socket fds involved
* in the proxied connection.
*/
static int
proxy_connection_io_dispatch (struct proxy_connection *pc,
const int rwflags,
struct event_set *es)
{
const int max_transfer_per_iteration = 10000;
struct proxy_connection *cp = pc->counterpart;
int rwflags_pc = pc->rwflags;
int rwflags_cp = cp->rwflags;
if (rwflags & EVENT_READ)
{
const int status = proxy_connection_io_xfer (pc, max_transfer_per_iteration);
if (!proxy_connection_io_status (status, &rwflags_pc, &rwflags_cp))
goto bad;
}
if (rwflags & EVENT_WRITE)
{
const int status = proxy_connection_io_xfer (cp, max_transfer_per_iteration);
if (!proxy_connection_io_status (status, &rwflags_cp, &rwflags_pc))
goto bad;
}
proxy_connection_io_requeue (pc, rwflags_pc, es);
proxy_connection_io_requeue (cp, rwflags_cp, es);
return true;
bad:
proxy_entry_mark_for_close (pc, es);
return false;
}
/*
* This is the main function for the port share proxy background process.
*/
static void
port_share_proxy (const in_addr_t hostaddr, const int port, const socket_descriptor_t sd_control)
{
if (send_control (sd_control, RESPONSE_INIT_SUCCEEDED) >= 0)
{
void *sd_control_marker = (void *)1;
int maxevents = 256;
struct event_set *es;
struct event_set_return esr[64];
struct proxy_connection *list = NULL;
time_t last_housekeeping = 0;
msg (D_PS_PROXY, "PORT SHARE PROXY: proxy starting");
es = event_set_init (&maxevents, 0);
event_ctl (es, sd_control, EVENT_READ, sd_control_marker);
while (true)
{
int n_events;
struct timeval tv;
time_t current;
tv.tv_sec = 10;
tv.tv_usec = 0;
n_events = event_wait (es, &tv, esr, SIZE(esr));
/*dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: event_wait returned %d", n_events);*/
current = time(NULL);
if (n_events > 0)
{
int i;
for (i = 0; i < n_events; ++i)
{
const struct event_set_return *e = &esr[i];
if (e->arg == sd_control_marker)
{
if (!control_message_from_parent (sd_control, &list, es, hostaddr, port))
goto done;
}
else
{
struct proxy_connection *pc = (struct proxy_connection *)e->arg;
if (pc->defined)
proxy_connection_io_dispatch (pc, e->rwflags, es);
}
}
}
else if (n_events < 0)
{
dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: event_wait failed");
}
if (current > last_housekeeping)
{
proxy_list_housekeeping (&list);
last_housekeeping = current;
}
}
done:
proxy_list_close (&list);
event_free (es);
}
msg (D_PS_PROXY, "PORT SHARE PROXY: proxy exiting");
}
/*
* Called from the main OpenVPN process to enable the port
* share proxy.
*/
struct port_share *
port_share_open (const char *host, const int port)
{
pid_t pid;
socket_descriptor_t fd[2];
in_addr_t hostaddr;
struct port_share *ps;
ALLOC_OBJ_CLEAR (ps, struct port_share);
/*
* Get host's IP address
*/
hostaddr = getaddr (GETADDR_RESOLVE|GETADDR_HOST_ORDER|GETADDR_FATAL, host, 0, NULL, NULL);
/*
* Make a socket for foreground and background processes
* to communicate.
*/
if (socketpair (PF_UNIX, SOCK_DGRAM, 0, fd) == -1)
{
msg (M_WARN, "PORT SHARE: socketpair call failed");
goto error;
}
/*
* Fork off background proxy process.
*/
pid = fork ();
if (pid)
{
int status;
/*
* Foreground Process
*/
ps->background_pid = pid;
/* close our copy of child's socket */
openvpn_close_socket (fd[1]);
/* don't let future subprocesses inherit child socket */
set_cloexec (fd[0]);
/* wait for background child process to initialize */
status = recv_control (fd[0]);
if (status == RESPONSE_INIT_SUCCEEDED)
{
ps->foreground_fd = fd[0];
return ps;
}
}
else
{
/*
* Background Process
*/
/* Ignore most signals (the parent will receive them) */
set_signals ();
/* Let msg know that we forked */
msg_forked ();
/* close all parent fds except our socket back to parent */
close_fds_except (fd[1]);
/* no blocking on control channel back to parent */
set_nonblock (fd[1]);
/* initialize prng */
prng_init (NULL, 0);
/* execute the event loop */
port_share_proxy (hostaddr, port, fd[1]);
openvpn_close_socket (fd[1]);
exit (0);
return 0; /* NOTREACHED */
}
error:
port_share_close (ps);
return NULL;
}
void
port_share_close (struct port_share *ps)
{
if (ps)
{
if (ps->foreground_fd >= 0)
{
/* tell background process to exit */
port_share_sendmsg (ps->foreground_fd, COMMAND_EXIT, NULL, SOCKET_UNDEFINED);
/* wait for background process to exit */
dmsg (D_PS_PROXY_DEBUG, "PORT SHARE: waiting for background process to exit");
if (ps->background_pid > 0)
waitpid (ps->background_pid, NULL, 0);
dmsg (D_PS_PROXY_DEBUG, "PORT SHARE: background process exited");
openvpn_close_socket (ps->foreground_fd);
ps->foreground_fd = -1;
}
free (ps);
}
}
void
port_share_abort (struct port_share *ps)
{
if (ps)
{
/* tell background process to exit */
if (ps->foreground_fd >= 0)
{
send_control (ps->foreground_fd, COMMAND_EXIT);
openvpn_close_socket (ps->foreground_fd);
ps->foreground_fd = -1;
}
}
}
/*
* Given either the first 2 or 3 bytes of an initial client -> server
* data payload, return true if the protocol is that of an OpenVPN
* client attempting to connect with an OpenVPN server.
*/
bool
is_openvpn_protocol (const struct buffer *buf)
{
const unsigned char *p = (const unsigned char *) BSTR (buf);
const int len = BLEN (buf);
if (len >= 3)
{
return p[0] == 0
&& p[1] >= 14
&& p[2] == (P_CONTROL_HARD_RESET_CLIENT_V2<<P_OPCODE_SHIFT);
}
else if (len >= 2)
{
return p[0] == 0 && p[1] >= 14;
}
else
return true;
}
/*
* Called from the foreground process. Send a message to the background process that it
* should proxy the TCP client on sd to the host/port defined in the initial port_share_open
* call.
*/
void
port_share_redirect (struct port_share *ps, const struct buffer *head, socket_descriptor_t sd)
{
if (ps)
port_share_sendmsg (ps->foreground_fd, COMMAND_REDIRECT, head, sd);
}
#endif