ZeroTierOne/osdep/LinuxEthernetTap.cpp

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/*
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* Copyright (c)2019 ZeroTier, Inc.
*
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* Use of this software is governed by the Business Source License included
* in the LICENSE.TXT file in the project's root directory.
*
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* Change Date: 2025-01-01
*
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* On the date above, in accordance with the Business Source License, use
* of this software will be governed by version 2.0 of the Apache License.
*/
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/****/
#include "../node/Constants.hpp"
#ifdef __LINUX__
#include "../node/Utils.hpp"
#include "../node/Mutex.hpp"
#include "../node/Dictionary.hpp"
#include "OSUtils.hpp"
#include "LinuxEthernetTap.hpp"
#include "LinuxNetLink.hpp"
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/wait.h>
#include <sys/select.h>
#include <netinet/in.h>
#include <net/if_arp.h>
#include <arpa/inet.h>
#include <linux/if.h>
#include <linux/if_tun.h>
#include <linux/if_addr.h>
#include <linux/if_ether.h>
#include <ifaddrs.h>
#include <algorithm>
#include <utility>
#include <string>
// ff:ff:ff:ff:ff:ff with no ADI
static const ZeroTier::MulticastGroup _blindWildcardMulticastGroup(ZeroTier::MAC(0xff),0);
namespace ZeroTier {
static Mutex __tapCreateLock;
static const char _base32_chars[32] = { 'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z','2','3','4','5','6','7' };
static void _base32_5_to_8(const uint8_t *in,char *out)
{
out[0] = _base32_chars[(in[0]) >> 3];
out[1] = _base32_chars[(in[0] & 0x07) << 2 | (in[1] & 0xc0) >> 6];
out[2] = _base32_chars[(in[1] & 0x3e) >> 1];
out[3] = _base32_chars[(in[1] & 0x01) << 4 | (in[2] & 0xf0) >> 4];
out[4] = _base32_chars[(in[2] & 0x0f) << 1 | (in[3] & 0x80) >> 7];
out[5] = _base32_chars[(in[3] & 0x7c) >> 2];
out[6] = _base32_chars[(in[3] & 0x03) << 3 | (in[4] & 0xe0) >> 5];
out[7] = _base32_chars[(in[4] & 0x1f)];
}
LinuxEthernetTap::LinuxEthernetTap(
const char *homePath,
const MAC &mac,
unsigned int mtu,
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unsigned int metric,
uint64_t nwid,
const char *friendlyName,
void (*handler)(void *,void *,uint64_t,const MAC &,const MAC &,unsigned int,unsigned int,const void *,unsigned int),
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void *arg) :
_handler(handler),
_arg(arg),
_nwid(nwid),
_homePath(homePath),
_mtu(mtu),
_fd(0),
_enabled(true)
{
char procpath[128],nwids[32];
struct stat sbuf;
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// ensure netlink connection is started
(void)LinuxNetLink::getInstance();
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OSUtils::ztsnprintf(nwids,sizeof(nwids),"%.16llx",nwid);
Mutex::Lock _l(__tapCreateLock); // create only one tap at a time, globally
_fd = ::open("/dev/net/tun",O_RDWR);
if (_fd <= 0) {
_fd = ::open("/dev/tun",O_RDWR);
if (_fd <= 0)
throw std::runtime_error(std::string("could not open TUN/TAP device: ") + strerror(errno));
}
struct ifreq ifr;
memset(&ifr,0,sizeof(ifr));
// Restore device names from legacy devicemap, but for new devices we use a base32-based canonical naming
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std::map<std::string,std::string> globalDeviceMap;
FILE *devmapf = fopen((_homePath + ZT_PATH_SEPARATOR_S + "devicemap").c_str(),"r");
if (devmapf) {
char buf[256];
while (fgets(buf,sizeof(buf),devmapf)) {
char *x = (char *)0;
char *y = (char *)0;
char *saveptr = (char *)0;
for(char *f=Utils::stok(buf,"\r\n=",&saveptr);(f);f=Utils::stok((char *)0,"\r\n=",&saveptr)) {
if (!x) x = f;
else if (!y) y = f;
else break;
}
if ((x)&&(y)&&(x[0])&&(y[0]))
globalDeviceMap[x] = y;
}
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fclose(devmapf);
}
bool recalledDevice = false;
std::map<std::string,std::string>::const_iterator gdmEntry = globalDeviceMap.find(nwids);
if (gdmEntry != globalDeviceMap.end()) {
Utils::scopy(ifr.ifr_name,sizeof(ifr.ifr_name),gdmEntry->second.c_str());
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OSUtils::ztsnprintf(procpath,sizeof(procpath),"/proc/sys/net/ipv4/conf/%s",ifr.ifr_name);
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recalledDevice = (stat(procpath,&sbuf) != 0);
}
if (!recalledDevice) {
#ifdef __SYNOLOGY__
int devno = 50;
do {
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OSUtils::ztsnprintf(ifr.ifr_name,sizeof(ifr.ifr_name),"eth%d",devno++);
OSUtils::ztsnprintf(procpath,sizeof(procpath),"/proc/sys/net/ipv4/conf/%s",ifr.ifr_name);
} while (stat(procpath,&sbuf) == 0); // try zt#++ until we find one that does not exist
#else
uint64_t trial = 0; // incremented in the very unlikely event of a name collision with another network
do {
const uint64_t nwid40 = (nwid ^ (nwid >> 24)) + trial++;
uint8_t tmp2[5];
char tmp3[11];
tmp2[0] = (uint8_t)((nwid40 >> 32) & 0xff);
tmp2[1] = (uint8_t)((nwid40 >> 24) & 0xff);
tmp2[2] = (uint8_t)((nwid40 >> 16) & 0xff);
tmp2[3] = (uint8_t)((nwid40 >> 8) & 0xff);
tmp2[4] = (uint8_t)(nwid40 & 0xff);
tmp3[0] = 'z';
tmp3[1] = 't';
_base32_5_to_8(tmp2,tmp3 + 2);
tmp3[10] = (char)0;
memcpy(ifr.ifr_name,tmp3,11);
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OSUtils::ztsnprintf(procpath,sizeof(procpath),"/proc/sys/net/ipv4/conf/%s",ifr.ifr_name);
} while (stat(procpath,&sbuf) == 0);
#endif
}
ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
if (ioctl(_fd,TUNSETIFF,(void *)&ifr) < 0) {
::close(_fd);
throw std::runtime_error("unable to configure TUN/TAP device for TAP operation");
}
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::ioctl(_fd,TUNSETPERSIST,0); // valgrind may generate a false alarm here
_dev = ifr.ifr_name;
// Set close-on-exec so that devices cannot persist if we fork/exec for update
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::fcntl(_fd,F_SETFD,fcntl(_fd,F_GETFD) | FD_CLOEXEC);
(void)::pipe(_shutdownSignalPipe);
_thread = Thread::start(this);
}
LinuxEthernetTap::~LinuxEthernetTap()
{
(void)::write(_shutdownSignalPipe[1],"\0",1); // causes thread to exit
Thread::join(_thread);
::close(_fd);
::close(_shutdownSignalPipe[0]);
::close(_shutdownSignalPipe[1]);
}
void LinuxEthernetTap::setEnabled(bool en)
{
_enabled = en;
}
bool LinuxEthernetTap::enabled() const
{
return _enabled;
}
static bool ___removeIp(const std::string &_dev,const InetAddress &ip)
{
LinuxNetLink::getInstance().removeAddress(ip, _dev.c_str());
return true;
}
bool LinuxEthernetTap::addIps(std::vector<InetAddress> ips)
{
#ifdef __SYNOLOGY__
std::string filepath = "/etc/sysconfig/network-scripts/ifcfg-"+_dev;
std::string cfg_contents = "DEVICE="+_dev+"\nBOOTPROTO=static";
int ip4=0,ip6=0,ip4_tot=0,ip6_tot=0;
for(int i=0; i<(int)ips.size(); i++) {
if (ips[i].isV4())
ip4_tot++;
else
ip6_tot++;
}
// Assemble and write contents of ifcfg-dev file
for(int i=0; i<(int)ips.size(); i++) {
if (ips[i].isV4()) {
char iptmp[64],iptmp2[64];
std::string numstr4 = ip4_tot > 1 ? std::to_string(ip4) : "";
cfg_contents += "\nIPADDR"+numstr4+"="+ips[i].toIpString(iptmp)
+ "\nNETMASK"+numstr4+"="+ips[i].netmask().toIpString(iptmp2)+"\n";
ip4++;
} else {
char iptmp[64],iptmp2[64];
std::string numstr6 = ip6_tot > 1 ? std::to_string(ip6) : "";
cfg_contents += "\nIPV6ADDR"+numstr6+"="+ips[i].toIpString(iptmp)
+ "\nNETMASK"+numstr6+"="+ips[i].netmask().toIpString(iptmp2)+"\n";
ip6++;
}
}
OSUtils::writeFile(filepath.c_str(), cfg_contents.c_str(), cfg_contents.length());
// Finally, add IPs
for(int i=0; i<(int)ips.size(); i++){
LinuxNetLink::getInstance().addAddress(ips[i], _dev.c_str());
}
return true;
#endif // __SYNOLOGY__
return false;
}
bool LinuxEthernetTap::addIp(const InetAddress &ip)
{
if (!ip)
return false;
std::vector<InetAddress> allIps(ips());
if (std::binary_search(allIps.begin(),allIps.end(),ip))
return true;
// Remove and reconfigure if address is the same but netmask is different
for(std::vector<InetAddress>::iterator i(allIps.begin());i!=allIps.end();++i) {
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if (i->ipsEqual(ip))
___removeIp(_dev,*i);
}
LinuxNetLink::getInstance().addAddress(ip, _dev.c_str());
return true;
}
bool LinuxEthernetTap::removeIp(const InetAddress &ip)
{
if (!ip)
return true;
std::vector<InetAddress> allIps(ips());
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if (std::find(allIps.begin(),allIps.end(),ip) != allIps.end()) {
if (___removeIp(_dev,ip))
return true;
}
return false;
}
std::vector<InetAddress> LinuxEthernetTap::ips() const
{
struct ifaddrs *ifa = (struct ifaddrs *)0;
if (getifaddrs(&ifa))
return std::vector<InetAddress>();
std::vector<InetAddress> r;
struct ifaddrs *p = ifa;
while (p) {
if ((!strcmp(p->ifa_name,_dev.c_str()))&&(p->ifa_addr)&&(p->ifa_netmask)&&(p->ifa_addr->sa_family == p->ifa_netmask->sa_family)) {
switch(p->ifa_addr->sa_family) {
case AF_INET: {
struct sockaddr_in *sin = (struct sockaddr_in *)p->ifa_addr;
struct sockaddr_in *nm = (struct sockaddr_in *)p->ifa_netmask;
r.push_back(InetAddress(&(sin->sin_addr.s_addr),4,Utils::countBits((uint32_t)nm->sin_addr.s_addr)));
} break;
case AF_INET6: {
struct sockaddr_in6 *sin = (struct sockaddr_in6 *)p->ifa_addr;
struct sockaddr_in6 *nm = (struct sockaddr_in6 *)p->ifa_netmask;
uint32_t b[4];
memcpy(b,nm->sin6_addr.s6_addr,sizeof(b));
r.push_back(InetAddress(sin->sin6_addr.s6_addr,16,Utils::countBits(b[0]) + Utils::countBits(b[1]) + Utils::countBits(b[2]) + Utils::countBits(b[3])));
} break;
}
}
p = p->ifa_next;
}
if (ifa)
freeifaddrs(ifa);
std::sort(r.begin(),r.end());
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r.erase(std::unique(r.begin(),r.end()),r.end());
return r;
}
void LinuxEthernetTap::put(const MAC &from,const MAC &to,unsigned int etherType,const void *data,unsigned int len)
{
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char putBuf[ZT_MAX_MTU + 64];
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if ((_fd > 0)&&(len <= _mtu)&&(_enabled)) {
to.copyTo(putBuf,6);
from.copyTo(putBuf + 6,6);
*((uint16_t *)(putBuf + 12)) = htons((uint16_t)etherType);
memcpy(putBuf + 14,data,len);
len += 14;
(void)::write(_fd,putBuf,len);
}
}
std::string LinuxEthernetTap::deviceName() const
{
return _dev;
}
void LinuxEthernetTap::setFriendlyName(const char *friendlyName)
{
}
void LinuxEthernetTap::scanMulticastGroups(std::vector<MulticastGroup> &added,std::vector<MulticastGroup> &removed)
{
char *ptr,*ptr2;
unsigned char mac[6];
std::vector<MulticastGroup> newGroups;
int fd = ::open("/proc/net/dev_mcast",O_RDONLY);
if (fd > 0) {
char buf[131072];
int n = (int)::read(fd,buf,sizeof(buf));
if ((n > 0)&&(n < (int)sizeof(buf))) {
buf[n] = (char)0;
for(char *l=strtok_r(buf,"\r\n",&ptr);(l);l=strtok_r((char *)0,"\r\n",&ptr)) {
int fno = 0;
char *devname = (char *)0;
char *mcastmac = (char *)0;
for(char *f=strtok_r(l," \t",&ptr2);(f);f=strtok_r((char *)0," \t",&ptr2)) {
if (fno == 1)
devname = f;
else if (fno == 4)
mcastmac = f;
++fno;
}
if ((devname)&&(!strcmp(devname,_dev.c_str()))&&(mcastmac)&&(Utils::unhex(mcastmac,mac,6) == 6))
newGroups.push_back(MulticastGroup(MAC(mac,6),0));
}
}
::close(fd);
}
std::vector<InetAddress> allIps(ips());
for(std::vector<InetAddress>::iterator ip(allIps.begin());ip!=allIps.end();++ip)
newGroups.push_back(MulticastGroup::deriveMulticastGroupForAddressResolution(*ip));
std::sort(newGroups.begin(),newGroups.end());
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newGroups.erase(std::unique(newGroups.begin(),newGroups.end()),newGroups.end());
for(std::vector<MulticastGroup>::iterator m(newGroups.begin());m!=newGroups.end();++m) {
if (!std::binary_search(_multicastGroups.begin(),_multicastGroups.end(),*m))
added.push_back(*m);
}
for(std::vector<MulticastGroup>::iterator m(_multicastGroups.begin());m!=_multicastGroups.end();++m) {
if (!std::binary_search(newGroups.begin(),newGroups.end(),*m))
removed.push_back(*m);
}
_multicastGroups.swap(newGroups);
}
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void LinuxEthernetTap::setMtu(unsigned int mtu)
{
if (_mtu != mtu) {
_mtu = mtu;
int sock = socket(AF_INET,SOCK_DGRAM,0);
if (sock > 0) {
struct ifreq ifr;
memset(&ifr,0,sizeof(ifr));
ifr.ifr_ifru.ifru_mtu = (int)mtu;
ioctl(sock,SIOCSIFMTU,(void *)&ifr);
close(sock);
}
}
}
void LinuxEthernetTap::threadMain()
throw()
{
fd_set readfds,nullfds;
MAC to,from;
int n,nfds,r;
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char getBuf[ZT_MAX_MTU + 64];
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Thread::sleep(100);
{
struct ifreq ifr;
memset(&ifr,0,sizeof(ifr));
strcpy(ifr.ifr_name,_dev.c_str());
const int sock = socket(AF_INET,SOCK_DGRAM,0);
if (sock <= 0)
return;
if (ioctl(sock,SIOCGIFFLAGS,(void *)&ifr) < 0) {
::close(sock);
printf("WARNING: ioctl() failed setting up Linux tap device (bring interface up)\n");
return;
}
ifr.ifr_flags |= IFF_UP;
if (ioctl(sock,SIOCSIFFLAGS,(void *)&ifr) < 0) {
::close(sock);
printf("WARNING: ioctl() failed setting up Linux tap device (bring interface up)\n");
return;
}
Thread::sleep(500);
ifr.ifr_ifru.ifru_hwaddr.sa_family = ARPHRD_ETHER;
mac.copyTo(ifr.ifr_ifru.ifru_hwaddr.sa_data,6);
if (ioctl(sock,SIOCSIFHWADDR,(void *)&ifr) < 0) {
::close(sock);
printf("WARNING: ioctl() failed setting up Linux tap device (set MAC)\n");
return;
}
ifr.ifr_ifru.ifru_mtu = (int)mtu;
if (ioctl(sock,SIOCSIFMTU,(void *)&ifr) < 0) {
::close(sock);
printf("WARNING: ioctl() failed setting up Linux tap device (set MTU)\n");
return;
}
if (fcntl(_fd,F_SETFL,fcntl(_fd,F_GETFL) & ~O_NONBLOCK) == -1) {
::close(sock);
printf("WARNING: ioctl() failed setting up Linux tap device (set non-blocking)\n");
return;
}
::close(sock);
}
FD_ZERO(&readfds);
FD_ZERO(&nullfds);
nfds = (int)std::max(_shutdownSignalPipe[0],_fd) + 1;
r = 0;
for(;;) {
FD_SET(_shutdownSignalPipe[0],&readfds);
FD_SET(_fd,&readfds);
select(nfds,&readfds,&nullfds,&nullfds,(struct timeval *)0);
if (FD_ISSET(_shutdownSignalPipe[0],&readfds)) // writes to shutdown pipe terminate thread
break;
if (FD_ISSET(_fd,&readfds)) {
n = (int)::read(_fd,getBuf + r,sizeof(getBuf) - r);
if (n < 0) {
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if ((errno != EINTR)&&(errno != ETIMEDOUT))
break;
} else {
// Some tap drivers like to send the ethernet frame and the
// payload in two chunks, so handle that by accumulating
// data until we have at least a frame.
r += n;
if (r > 14) {
if (r > ((int)_mtu + 14)) // sanity check for weird TAP behavior on some platforms
r = _mtu + 14;
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if (_enabled) {
to.setTo(getBuf,6);
from.setTo(getBuf + 6,6);
unsigned int etherType = ntohs(((const uint16_t *)getBuf)[6]);
// TODO: VLAN support
_handler(_arg,(void *)0,_nwid,from,to,etherType,0,(const void *)(getBuf + 14),r - 14);
}
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r = 0;
}
}
}
}
}
} // namespace ZeroTier
#endif // __LINUX__