ZeroTierOne/netcon/Intercept.c
2016-01-25 12:55:29 -08:00

576 lines
18 KiB
C

/*
* ZeroTier One - Network Virtualization Everywhere
* Copyright (C) 2011-2015 ZeroTier, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* 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. If not, see <http://www.gnu.org/licenses/>.
*
* --
*
* ZeroTier may be used and distributed under the terms of the GPLv3, which
* are available at: http://www.gnu.org/licenses/gpl-3.0.html
*
* If you would like to embed ZeroTier into a commercial application or
* redistribute it in a modified binary form, please contact ZeroTier Networks
* LLC. Start here: http://www.zerotier.com/
*/
#ifdef USE_GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <unistd.h>
#include <stdint.h>
#include <stdio.h>
#include <dlfcn.h>
#include <strings.h>
#include <netinet/in.h>
#include <sys/time.h>
#include <pwd.h>
#include <errno.h>
#include <stdarg.h>
#include <netdb.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/poll.h>
#include <sys/un.h>
#include <arpa/inet.h>
#include <sys/resource.h>
#if defined(__linux__)
#include <linux/errno.h>
#include <sys/syscall.h>
#include <linux/net.h> /* for NPROTO */
#endif
#if defined(__linux__)
#define SOCK_MAX (SOCK_PACKET + 1)
#endif
#define SOCK_TYPE_MASK 0xf
#include "Intercept.h"
#include "RPC.h"
#include "common.inc.c"
/*------------------------------------------------------------------------------
------------------- Intercept<--->Service Comm mechanisms ----------------------
------------------------------------------------------------------------------*/
static char *netpath = (char *)0;
/* Check whether the socket is mapped to the service or not. We
need to know if this is a regular AF_LOCAL socket or an end of a socketpair
that the service uses. We don't want to keep state in the intercept, so
we simply ask the service via an RPC */
static int connected_to_service(int sockfd)
{
dwr(MSG_DEBUG,"connected_to_service():\n");
socklen_t len;
struct sockaddr_storage addr;
len = sizeof addr;
struct sockaddr_un * addr_un;
getpeername(sockfd, (struct sockaddr*)&addr, &len);
if (addr.ss_family == AF_LOCAL || addr.ss_family == AF_LOCAL) {
addr_un = (struct sockaddr_un*)&addr;
if(strcmp(addr_un->sun_path, netpath) == 0) {
dwr(MSG_DEBUG,"connected_to_service(): Yes, %s\n", addr_un->sun_path);
return 1;
}
}
dwr(MSG_DEBUG,"connected_to_service(): Not connected to service\n");
return 0;
}
/* get symbols and initialize mutexes */
static int set_up_intercept()
{
if (!realconnect) {
#if defined(__linux__)
realaccept4 = dlsym(RTLD_NEXT, "accept4");
realsyscall = dlsym(RTLD_NEXT, "syscall");
#endif
realconnect = dlsym(RTLD_NEXT, "connect");
realbind = dlsym(RTLD_NEXT, "bind");
realaccept = dlsym(RTLD_NEXT, "accept");
reallisten = dlsym(RTLD_NEXT, "listen");
realsocket = dlsym(RTLD_NEXT, "socket");
realbind = dlsym(RTLD_NEXT, "bind");
realsetsockopt = dlsym(RTLD_NEXT, "setsockopt");
realgetsockopt = dlsym(RTLD_NEXT, "getsockopt");
realclose = dlsym(RTLD_NEXT, "close");
realgetsockname = dlsym(RTLD_NEXT, "getsockname");
}
if (!netpath) {
netpath = getenv("ZT_NC_NETWORK");
if (!netpath)
return 0;
dwr(MSG_DEBUG,"Connecting to service at: %s\n", netpath);
/* Hook/intercept Posix net API symbols */
rpc_mutex_init();
}
return 1;
}
/*------------------------------------------------------------------------------
--------------------------------- setsockopt() ---------------------------------
------------------------------------------------------------------------------*/
/* int socket, int level, int option_name, const void *option_value, socklen_t option_len */
int setsockopt(SETSOCKOPT_SIG)
{
if (!set_up_intercept())
return realsetsockopt(socket, level, option_name, option_value, option_len);
dwr(MSG_DEBUG,"setsockopt(%d)\n", socket);
#if defined(__linux__)
if(level == SOL_IPV6 && option_name == IPV6_V6ONLY)
return 0;
if(level == SOL_IP && (option_name == IP_TTL || option_name == IP_TOS))
return 0;
#endif
if(level == IPPROTO_TCP || (level == SOL_SOCKET && option_name == SO_KEEPALIVE))
return 0;
if(realsetsockopt(socket, level, option_name, option_value, option_len) < 0)
perror("setsockopt():\n");
return 0;
}
/*------------------------------------------------------------------------------
--------------------------------- getsockopt() ---------------------------------
------------------------------------------------------------------------------*/
/* int sockfd, int level, int optname, void *optval, socklen_t *optlen */
int getsockopt(GETSOCKOPT_SIG)
{
dwr(MSG_DEBUG,"getsockopt(%d)\n", sockfd);
if (!set_up_intercept() || !connected_to_service(sockfd))
return realgetsockopt(sockfd, level, optname, optval, optlen);
if(optname == SO_TYPE) {
int* val = (int*)optval;
*val = 2;
optval = (void*)val;
}
return 0;
}
/*------------------------------------------------------------------------------
----------------------------------- socket() -----------------------------------
------------------------------------------------------------------------------*/
/* int socket_family, int socket_type, int protocol
socket() intercept function */
int socket(SOCKET_SIG)
{
if (!set_up_intercept())
return realsocket(socket_family, socket_type, protocol);
dwr(MSG_DEBUG,"socket():\n");
/* Check that type makes sense */
#if defined(__linux__)
int flags = socket_type & ~SOCK_TYPE_MASK;
if (flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK)) {
errno = EINVAL;
return -1;
}
#endif
socket_type &= SOCK_TYPE_MASK;
/* Check protocol is in range */
#if defined(__linux__)
if (socket_family < 0 || socket_family >= NPROTO){
errno = EAFNOSUPPORT;
return -1;
}
if (socket_type < 0 || socket_type >= SOCK_MAX) {
errno = EINVAL;
return -1;
}
#endif
/* TODO: detect ENFILE condition */
if(socket_family == AF_LOCAL
#if defined(__linux__)
|| socket_family == AF_NETLINK
#endif
|| socket_family == AF_UNIX) {
int err = realsocket(socket_family, socket_type, protocol);
dwr(MSG_DEBUG,"realsocket() = %d\n", err);
return err;
}
/* Assemble and send RPC */
struct socket_st rpc_st;
rpc_st.socket_family = socket_family;
rpc_st.socket_type = socket_type;
rpc_st.protocol = protocol;
rpc_st.__tid = syscall(SYS_gettid);
/* -1 is passed since we we're generating the new socket in this call */
return rpc_send_command(netpath, RPC_SOCKET, -1, &rpc_st, sizeof(struct socket_st));
}
/*------------------------------------------------------------------------------
---------------------------------- connect() -----------------------------------
------------------------------------------------------------------------------*/
/* int __fd, const struct sockaddr * __addr, socklen_t __len
connect() intercept function */
int connect(CONNECT_SIG)
{
if (!set_up_intercept())
return realconnect(__fd, __addr, __len);
struct sockaddr_in *connaddr;
connaddr = (struct sockaddr_in *)__addr;
if(__addr->sa_family == AF_LOCAL || __addr->sa_family == AF_UNIX) {
struct sockaddr_storage storage;
memcpy(&storage, __addr, __len);
struct sockaddr_un *s_un = (struct sockaddr_un*)&storage;
dwr(MSG_DEBUG, "connect(): address = %s\n", s_un->sun_path);
}
int port = connaddr->sin_port;
int ip = connaddr->sin_addr.s_addr;
unsigned char d[4];
d[0] = ip & 0xFF;
d[1] = (ip >> 8) & 0xFF;
d[2] = (ip >> 16) & 0xFF;
d[3] = (ip >> 24) & 0xFF;
dwr(MSG_DEBUG,"connect(): %d.%d.%d.%d: %d\n", d[0],d[1],d[2],d[3], ntohs(port));
dwr(MSG_DEBUG,"connect(%d):\n", __fd);
/* Check that this is a valid fd */
if(fcntl(__fd, F_GETFD) < 0) {
errno = EBADF;
return -1;
}
/* Check that it is a socket */
int sock_type;
socklen_t sock_type_len = sizeof(sock_type);
if(getsockopt(__fd, SOL_SOCKET, SO_TYPE, (void *) &sock_type, &sock_type_len) < 0) {
errno = ENOTSOCK;
return -1;
}
#if defined(__linux__)
/* Check family */
if (connaddr->sin_family < 0 || connaddr->sin_family >= NPROTO){
errno = EAFNOSUPPORT;
return -1;
}
#endif
/* make sure we don't touch any standard outputs */
if(__fd == STDIN_FILENO || __fd == STDOUT_FILENO || __fd == STDERR_FILENO)
return(realconnect(__fd, __addr, __len));
if(__addr != NULL && (connaddr->sin_family == AF_LOCAL
#if defined(__linux__)
|| connaddr->sin_family == PF_NETLINK
|| connaddr->sin_family == AF_NETLINK
#endif
|| connaddr->sin_family == AF_UNIX)) {
return realconnect(__fd, __addr, __len);
}
/* Assemble and send RPC */
struct connect_st rpc_st;
#if defined(__linux__)
rpc_st.__tid = syscall(SYS_gettid);
#endif
rpc_st.__fd = __fd;
memcpy(&rpc_st.__addr, __addr, sizeof(struct sockaddr_storage));
memcpy(&rpc_st.__len, &__len, sizeof(socklen_t));
return rpc_send_command(netpath, RPC_CONNECT, __fd, &rpc_st, sizeof(struct connect_st));
}
/*------------------------------------------------------------------------------
------------------------------------ bind() ------------------------------------
------------------------------------------------------------------------------*/
/* int sockfd, const struct sockaddr *addr, socklen_t addrlen
bind() intercept function */
int bind(BIND_SIG)
{
if (!set_up_intercept())
return realbind(sockfd, addr, addrlen);
dwr(MSG_DEBUG,"bind(%d):\n", sockfd);
/* Check that this is a valid fd */
if(fcntl(sockfd, F_GETFD) < 0) {
errno = EBADF;
return -1;
}
/* Check that it is a socket */
int opt = -1;
socklen_t opt_len;
if(getsockopt(sockfd, SOL_SOCKET, SO_TYPE, (void *) &opt, &opt_len) < 0) {
errno = ENOTSOCK;
return -1;
}
/* make sure we don't touch any standard outputs */
if(sockfd == STDIN_FILENO || sockfd == STDOUT_FILENO || sockfd == STDERR_FILENO)
return(realbind(sockfd, addr, addrlen));
/* If local, just use normal syscall */
struct sockaddr_in *connaddr;
connaddr = (struct sockaddr_in *)addr;
if(connaddr->sin_family == AF_LOCAL
#if defined(__linux__)
|| connaddr->sin_family == AF_NETLINK
#endif
|| connaddr->sin_family == AF_UNIX) {
int err = realbind(sockfd, addr, addrlen);
dwr(MSG_DEBUG,"realbind, err = %d\n", err);
return err;
}
int port = connaddr->sin_port;
int ip = connaddr->sin_addr.s_addr;
unsigned char d[4];
d[0] = ip & 0xFF;
d[1] = (ip >> 8) & 0xFF;
d[2] = (ip >> 16) & 0xFF;
d[3] = (ip >> 24) & 0xFF;
dwr(MSG_DEBUG,"bind(): %d.%d.%d.%d: %d\n", d[0],d[1],d[2],d[3], ntohs(port));
/* Assemble and send RPC */
struct bind_st rpc_st;
rpc_st.sockfd = sockfd;
#if defined(__linux__)
rpc_st.__tid = syscall(SYS_gettid);
#endif
memcpy(&rpc_st.addr, addr, sizeof(struct sockaddr_storage));
memcpy(&rpc_st.addrlen, &addrlen, sizeof(socklen_t));
return rpc_send_command(netpath, RPC_BIND, sockfd, &rpc_st, sizeof(struct bind_st));
}
/*------------------------------------------------------------------------------
----------------------------------- accept4() ----------------------------------
------------------------------------------------------------------------------*/
/* int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags */
#if defined(__linux__)
int accept4(ACCEPT4_SIG)
{
dwr(MSG_DEBUG,"accept4(%d):\n", sockfd);
if ((flags & SOCK_CLOEXEC))
fcntl(sockfd, F_SETFL, FD_CLOEXEC);
if ((flags & SOCK_NONBLOCK))
fcntl(sockfd, F_SETFL, O_NONBLOCK);
return accept(sockfd, addr, addrlen);
}
#endif
/*------------------------------------------------------------------------------
----------------------------------- accept() -----------------------------------
------------------------------------------------------------------------------*/
/* int sockfd struct sockaddr *addr, socklen_t *addrlen
accept() intercept function */
int accept(ACCEPT_SIG)
{
if (!set_up_intercept())
return realaccept(sockfd, addr, addrlen);
dwr(MSG_DEBUG,"accept(%d):\n", sockfd);
/* Check that this is a valid fd */
if(fcntl(sockfd, F_GETFD) < 0) {
return -1;
errno = EBADF;
dwr(MSG_DEBUG,"EBADF\n");
return -1;
}
/* Check that it is a socket */
int opt;
socklen_t opt_len;
if(getsockopt(sockfd, SOL_SOCKET, SO_TYPE, (void *) &opt, &opt_len) < 0) {
errno = ENOTSOCK;
dwr(MSG_DEBUG,"ENOTSOCK\n");
return -1;
}
/* Check that this socket supports accept() */
if(!(opt && (SOCK_STREAM | SOCK_SEQPACKET))) {
errno = EOPNOTSUPP;
dwr(MSG_DEBUG,"EOPNOTSUPP\n");
return -1;
}
/* Check that we haven't hit the soft-limit file descriptors allowed */
struct rlimit rl;
getrlimit(RLIMIT_NOFILE, &rl);
if(sockfd >= rl.rlim_cur){
errno = EMFILE;
dwr(MSG_DEBUG,"EMFILE\n");
return -1;
}
/* Check address length */
if(addrlen < 0) {
errno = EINVAL;
dwr(MSG_DEBUG,"EINVAL\n");
return -1;
}
/* redirect calls for standard I/O descriptors to kernel */
if(sockfd == STDIN_FILENO || sockfd == STDOUT_FILENO || sockfd == STDERR_FILENO){
dwr(MSG_DEBUG,"realaccept():\n");
return(realaccept(sockfd, addr, addrlen));
}
if(addr)
addr->sa_family = AF_INET;
int new_fd = get_new_fd(sockfd);
if(new_fd > 0) {
errno = ERR_OK;
return new_fd;
}
errno = EAGAIN;
return -EAGAIN;
}
/*------------------------------------------------------------------------------
------------------------------------- listen()----------------------------------
------------------------------------------------------------------------------*/
/* int sockfd, int backlog */
int listen(LISTEN_SIG)
{
if (!set_up_intercept())
return(reallisten(sockfd, backlog));
dwr(MSG_DEBUG,"listen(%d):\n", sockfd);
int sock_type;
socklen_t sock_type_len = sizeof(sock_type);
/* Check that this is a valid fd */
if(fcntl(sockfd, F_GETFD) < 0) {
errno = EBADF;
return -1;
}
/* Check that it is a socket */
if(getsockopt(sockfd, SOL_SOCKET, SO_TYPE, (void *) &sock_type, &sock_type_len) < 0) {
errno = ENOTSOCK;
return -1;
}
/* Check that this socket supports accept() */
if(!(sock_type && (SOCK_STREAM | SOCK_SEQPACKET))) {
errno = EOPNOTSUPP;
return -1;
}
/* make sure we don't touch any standard outputs */
if(sockfd == STDIN_FILENO || sockfd == STDOUT_FILENO || sockfd == STDERR_FILENO)
return(reallisten(sockfd, backlog));
if(!connected_to_service(sockfd)) {
reallisten(sockfd, backlog);
}
/* Assemble and send RPC */
struct listen_st rpc_st;
rpc_st.sockfd = sockfd;
rpc_st.backlog = backlog;
#if defined(__linux__)
rpc_st.__tid = syscall(SYS_gettid);
#endif
return rpc_send_command(netpath, RPC_LISTEN, sockfd, &rpc_st, sizeof(struct listen_st));
}
/*------------------------------------------------------------------------------
------------------------------------- close() ----------------------------------
------------------------------------------------------------------------------*/
/* int fd */
int close(CLOSE_SIG)
{
dwr(MSG_DEBUG, "close(%d)\n", fd);
set_up_intercept();
return realclose(fd);
}
/*------------------------------------------------------------------------------
-------------------------------- getsockname() ---------------------------------
------------------------------------------------------------------------------*/
/* int sockfd, struct sockaddr *addr, socklen_t *addrlen */
int getsockname(GETSOCKNAME_SIG)
{
if (!set_up_intercept())
return realgetsockname(sockfd, addr, addrlen);
dwr(MSG_DEBUG,"getsockname(%d)\n", sockfd);
if(!connected_to_service(sockfd)) {
dwr(MSG_DEBUG,"getsockname(): not used by service\n");
return realgetsockname(sockfd, addr, addrlen);
}
/* This is kind of a hack as it stands -- assumes sockaddr is sockaddr_in
* and is an IPv4 address. */
/* assemble and send command */
struct getsockname_st rpc_st;
rpc_st.sockfd = sockfd;
memcpy(&rpc_st.addr, addr, *addrlen);
memcpy(&rpc_st.addrlen, &addrlen, sizeof(socklen_t));
int rpcfd = rpc_send_command(netpath, RPC_GETSOCKNAME, sockfd, &rpc_st, sizeof(struct getsockname_st));
/* read address info from service */
char addrbuf[sizeof(struct sockaddr_storage)];
memset(&addrbuf, 0, sizeof(struct sockaddr_storage));
if(rpcfd > -1)
if(read(rpcfd, &addrbuf, sizeof(struct sockaddr_storage)) > 0)
close(rpcfd);
struct sockaddr_storage sock_storage;
memcpy(&sock_storage, addrbuf, sizeof(struct sockaddr_storage));
*addrlen = sizeof(struct sockaddr_in);
memcpy(addr, &sock_storage, (*addrlen > sizeof(sock_storage)) ? sizeof(sock_storage) : *addrlen);
addr->sa_family = AF_INET;
return 0;
}
/*------------------------------------------------------------------------------
------------------------------------ syscall() ---------------------------------
------------------------------------------------------------------------------*/
#if defined(__linux__)
long syscall(SYSCALL_SIG)
{
va_list ap;
uintptr_t a,b,c,d,e,f;
va_start(ap, number);
a=va_arg(ap, uintptr_t);
b=va_arg(ap, uintptr_t);
c=va_arg(ap, uintptr_t);
d=va_arg(ap, uintptr_t);
e=va_arg(ap, uintptr_t);
f=va_arg(ap, uintptr_t);
va_end(ap);
if (!set_up_intercept())
return realsyscall(number,a,b,c,d,e,f);
dwr(MSG_DEBUG_EXTRA,"syscall(%u, ...):\n", number);
#if defined(__i386__)
/* TODO: Implement for 32-bit systems: syscall(__NR_socketcall, 18, args);
args[0] = (unsigned long) fd;
args[1] = (unsigned long) addr;
args[2] = (unsigned long) addrlen;
args[3] = (unsigned long) flags;
*/
#else
if(number == __NR_accept4) {
int sockfd = a;
struct sockaddr * addr = (struct sockaddr*)b;
socklen_t * addrlen = (socklen_t*)c;
int flags = d;
int old_errno = errno;
int err = accept4(sockfd, addr, addrlen, flags);
errno = old_errno;
err = err == -EBADF ? -EAGAIN : err;
return err;
}
#endif
return realsyscall(number,a,b,c,d,e,f);
}
#endif