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/*
* Copyright 2013 Google 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 2
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
/*
* Author: ncardwell@google.com (Neal Cardwell)
*
* API to read and write raw packets implemented using Linux packet socket.
*/
#include "packet_socket.h"
#include <errno.h>
#include <net/if.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/uio.h>
#include <unistd.h>
#ifdef linux
#include <netpacket/packet.h>
#include <linux/filter.h>
#include <linux/sockios.h>
#include "ethernet.h"
#include "logging.h"
/* Number of bytes to buffer in the packet socket we use for sniffing. */
static const int PACKET_SOCKET_RCVBUF_BYTES = 2*1024*1024;
struct packet_socket {
int packet_fd; /* socket for sending, sniffing timestamped packets */
char *name; /* malloc-allocated copy of interface name */
int index; /* interface index from if_nametoindex */
};
/* Set the receive buffer for a socket to the given size in bytes. */
static void set_receive_buffer_size(int fd, int bytes)
{
if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &bytes, sizeof(bytes)) < 0)
die_perror("setsockopt SOL_SOCKET SO_RCVBUF");
}
/* Bind the packet socket with the given fd to the given interface. */
static void bind_to_interface(int fd, int interface_index)
{
struct sockaddr_ll sll;
memset(&sll, 0, sizeof(sll));
sll.sll_family = AF_PACKET;
sll.sll_ifindex = interface_index;
sll.sll_protocol = htons(ETH_P_ALL);
if (bind(fd, (struct sockaddr *)&sll, sizeof(sll)) < 0)
die_perror("bind packet socket");
}
/* Allocate and configure a packet socket just like the one tcpdump
* uses. We do this so we can get timestamps on the outbound packets
* the kernel sends, to verify the correct timing (tun devices do not
* take timestamps). To reduce CPU load and filtering complexity, we
* bind the socket to a single device so we only receive packets for
* that device.
*/
static void packet_socket_setup(struct packet_socket *psock)
{
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committed
struct timeval tv;
psock->packet_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
if (psock->packet_fd < 0)
die_perror("socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))");
psock->index = if_nametoindex(psock->name);
if (psock->index == 0)
die_perror("if_nametoindex");
DEBUGP("device index: %s -> %d\n", psock->name, psock->index);
bind_to_interface(psock->packet_fd, psock->index);
set_receive_buffer_size(psock->packet_fd, PACKET_SOCKET_RCVBUF_BYTES);
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/* Pay the non-trivial latency cost to enable timestamps now, before
* the test starts, to avoid significant delays in the middle of tests.
*/
ioctl(psock->packet_fd, SIOCGSTAMP, &tv);
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}
/* Add a filter so we only sniff packets we want. */
void packet_socket_set_filter(struct packet_socket *psock,
const struct ether_addr *client_ether_addr,
const struct ip_address *client_live_ip)
{
const u8 *client_ether = client_ether_addr->ether_addr_octet;
struct sock_fprog bpfcode;
struct sock_filter bpf_ipv4_src[] = {
/* this filter works for ethernet interfaces: */
/* tcpdump -p -n -s 0 -i lo -dd
* "ether src 11:22:33:44:55:66 and ip src 1.2.3.4"
*/
{ 0x20, 0, 0, 0x00000008 },
{ 0x15, 0, 7, 0x33445566 }, /* ether: 33:44:55:66 */
{ 0x28, 0, 0, 0x00000006 },
{ 0x15, 0, 5, 0x00001122 }, /* ether: 11:22 */
{ 0x28, 0, 0, 0x0000000c },
{ 0x15, 0, 3, 0x00000800 },
{ 0x20, 0, 0, 0x0000001a },
{ 0x15, 0, 1, 0x01020304 }, /* IPv4: 1.2.3.4 */
{ 0x6, 0, 0, 0x0000ffff },
{ 0x6, 0, 0, 0x00000000 },
};
struct sock_filter bpf_ipv6_src[] = {
/* this filter works for ethernet interfaces: */
/* tcpdump -p -n -s 0 -i lo -dd
* "ether src 11:22:33:44:55:66 and ip6 src 1:2:3:4:5:6:7:8" */
{ 0x20, 0, 0, 0x00000008 },
{ 0x15, 0, 13, 0x33445566 }, /* ether: 33:44:55:66 */
{ 0x28, 0, 0, 0x00000006 },
{ 0x15, 0, 11, 0x00001122 }, /* ether: 11:22 */
{ 0x28, 0, 0, 0x0000000c },
{ 0x15, 0, 9, 0x000086dd },
{ 0x20, 0, 0, 0x00000016 },
{ 0x15, 0, 7, 0x00010002 }, /* IPv6: 1:2 */
{ 0x20, 0, 0, 0x0000001a },
{ 0x15, 0, 5, 0x00030004 }, /* IPv6: 3:4 */
{ 0x20, 0, 0, 0x0000001e },
{ 0x15, 0, 3, 0x00050006 }, /* IPv6: 5:6 */
{ 0x20, 0, 0, 0x00000022 },
{ 0x15, 0, 1, 0x00070008 }, /* IPv6: 7:8 */
{ 0x6, 0, 0, 0x0000ffff },
{ 0x6, 0, 0, 0x00000000 },
};
if (client_live_ip->address_family == AF_INET) {
/* Fill in the client-side IPv6 address to look for. */
bpf_ipv4_src[7].k = ntohl(client_live_ip->ip.v4.s_addr);
bpfcode.len = ARRAY_SIZE(bpf_ipv4_src);
bpfcode.filter = bpf_ipv4_src;
} else if (client_live_ip->address_family == AF_INET6) {
/* Fill in the client-side IPv6 address to look for. */
bpf_ipv6_src[7].k = ntohl(client_live_ip->ip.v6.s6_addr32[0]);
bpf_ipv6_src[9].k = ntohl(client_live_ip->ip.v6.s6_addr32[1]);
bpf_ipv6_src[11].k = ntohl(client_live_ip->ip.v6.s6_addr32[2]);
bpf_ipv6_src[13].k = ntohl(client_live_ip->ip.v6.s6_addr32[3]);
bpfcode.len = ARRAY_SIZE(bpf_ipv6_src);
bpfcode.filter = bpf_ipv6_src;
} else {
assert(!"bad address family");
}
/* Fill in the client-side ethernet address to look for. */
bpfcode.filter[1].k = (((u32)client_ether[2] << 24) |
((u32)client_ether[3] << 16) |
((u32)client_ether[4] << 8) |
((u32)client_ether[5]));
bpfcode.filter[3].k = (((u32)client_ether[0] << 8) |
int i;
DEBUGP("filter constants:\n");
for (i = 0; i < bpfcode.len; ++i)
DEBUGP("0x%x\n", bpfcode.filter[i].k);
}
/* Attach the filter. */
if (setsockopt(psock->packet_fd, SOL_SOCKET, SO_ATTACH_FILTER,
&bpfcode, sizeof(bpfcode)) < 0) {
die_perror("setsockopt SOL_SOCKET, SO_ATTACH_FILTER");
}
psock->trim_ethernet_header = true;
}
struct packet_socket *packet_socket_new(const char *device_name)
{
struct packet_socket *psock = calloc(1, sizeof(struct packet_socket));
psock->name = strdup(device_name);
psock->packet_fd = -1;
psock->trim_ethernet_header = false;
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packet_socket_setup(psock);
return psock;
}
void packet_socket_free(struct packet_socket *psock)
{
if (psock->packet_fd >= 0)
close(psock->packet_fd);
if (psock->name != NULL)
free(psock->name);
memset(psock, 0, sizeof(*psock)); /* paranoia to catch bugs*/
free(psock);
}
int packet_socket_writev(struct packet_socket *psock,
const struct iovec *iov, int iovcnt)
{
if (writev(psock->packet_fd, iov, iovcnt) < 0) {
perror("writev");
return STATUS_ERR;
}
return STATUS_OK;
}
int packet_socket_receive(struct packet_socket *psock,
enum direction_t direction, u16 *ether_type,
struct packet *packet, int *in_bytes)
{
struct sockaddr_ll from;
struct ether_header ether;
struct iovec iov[2];
struct msghdr msg;
/* Read the packet out of our kernel packet socket buffer. */
memset(&from, 0, sizeof(from));
if (psock->trim_ethernet_header) {
iov[0].iov_base = ðer;
iov[0].iov_len = sizeof(struct ether_header);
iov[1].iov_base = packet->buffer;
iov[1].iov_len = packet->buffer_bytes;
} else {
iov[0].iov_base = packet->buffer;
iov[0].iov_len = packet->buffer_bytes;
}
msg.msg_name = &from;
msg.msg_namelen = (socklen_t)sizeof(struct sockaddr_ll);
msg.msg_iov = iov;
msg.msg_iovlen = (psock->trim_ethernet_header == 1) ? 2 : 1;
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = 0;
*in_bytes = recvmsg(psock->packet_fd, &msg, 0);
if (psock->trim_ethernet_header)
assert(*in_bytes <=
packet->buffer_bytes + sizeof(struct ether_header));
else
assert(*in_bytes <= packet->buffer_bytes);
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if (*in_bytes < 0) {
if (errno == EINTR) {
DEBUGP("EINTR\n");
return STATUS_ERR;
} else {
die_perror("packet socket recvfrom()");
}
}
/* We only want packets our kernel is sending out. */
if (direction == DIRECTION_OUTBOUND &&
from.sll_pkttype != PACKET_OUTGOING) {
DEBUGP("not outbound\n");
return STATUS_ERR;
}
if (direction == DIRECTION_INBOUND &&
from.sll_pkttype != PACKET_HOST) {
DEBUGP("not inbound\n");
return STATUS_ERR;
}
/* We only want packets on our tun device. The kernel
* can put packets for other devices in our receive
* buffer before we bind the packet socket to the tun
* device.
*/
if (from.sll_ifindex != psock->index) {
DEBUGP("not correct index\n");
return STATUS_ERR;
}
/* Get the time at which the kernel sniffed the packet. */
struct timeval tv;
if (ioctl(psock->packet_fd, SIOCGSTAMP, &tv) < 0)
die_perror("SIOCGSTAMP");
packet->time_usecs = timeval_to_usecs(&tv);
DEBUGP("sniffed packet sent at %u.%u = %lld\n",
(u32)tv.tv_sec, (u32)tv.tv_usec,
packet->time_usecs);
DEBUGP("reported sll_protocol = 0x%04x\n", ntohs(from.sll_protocol));
if (psock->trim_ethernet_header) {
if (*in_bytes < sizeof(struct ether_header)) {
DEBUGP("packet does not contain ethernet header\n");
return STATUS_ERR;
} else {
*ether_type = ntohs(ether.ether_type);
*in_bytes -= sizeof(struct ether_header);
}
} else {
*ether_type = ntohs(from.sll_protocol);
}
DEBUGP("ether_type is 0x%04x\n", *ether_type);
return STATUS_OK;
}
#endif /* linux */