mirrors/passt
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions
passt/udp.c
David Gibson 3ede07aac9 Treat port numbers as unsigned 
Port numbers are unsigned values, but we're storing them in (signed) int
variables in some places.  This isn't actually harmful, because int is
large enough to hold the entire range of ports.  However in places we don't
want to use an in_port_t (usually to avoid overflow on the last iteration
of a loop) it makes more conceptual sense to use an unsigned int. This will
also avoid some problems with later cleanups.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
2022-09-24 14:48:35 +02:00

1363 lines
36 KiB
C
Raw Blame History

// SPDX-License-Identifier: AGPL-3.0-or-later
/* PASST - Plug A Simple Socket Transport
* for qemu/UNIX domain socket mode
*
* PASTA - Pack A Subtle Tap Abstraction
* for network namespace/tap device mode
*
* udp.c - UDP L2-L4 translation routines
*
* Copyright (c) 2020-2021 Red Hat GmbH
* Author: Stefano Brivio <sbrivio@redhat.com>
*/
/**
* DOC: Theory of Operation
*
*
* For UDP, a reduced version of port-based connection tracking is implemented
* with two purposes:
* - binding ephemeral ports when they're used as source port by the guest, so
* that replies on those ports can be forwarded back to the guest, with a
* fixed timeout for this binding
* - packets received from the local host get their source changed to a local
* address (gateway address) so that they can be forwarded to the guest, and
* packets sent as replies by the guest need their destination address to
* be changed back to the address of the local host. This is dynamic to allow
* connections from the gateway as well, and uses the same fixed 180s timeout
*
* Sockets for bound ports are created at initialisation time, one set for IPv4
* and one for IPv6.
*
* Packets are forwarded back and forth, by prepending and stripping UDP headers
* in the obvious way, with no port translation.
*
* In PASTA mode, the L2-L4 translation is skipped for connections to ports
* bound between namespaces using the loopback interface, messages are directly
* transferred between L4 sockets instead. These are called spliced connections
* for consistency with the TCP implementation, but the splice() syscall isn't
* actually used as it wouldn't make sense for datagram-based connections: a
* pair of recvmmsg() and sendmmsg() deals with this case.
*
* The connection tracking for PASTA mode is slightly complicated by the absence
* of actual connections, see struct udp_splice_port, and these examples:
*
* - from init to namespace:
*
* - forward direction: 127.0.0.1:5000 -> 127.0.0.1:80 in init from bound
* socket s, with epoll reference: index = 80, splice = UDP_TO_NS
* - if udp_splice_map[V4][5000].ns_conn_sock:
* - send packet to udp4_splice_map[5000].ns_conn_sock
* - otherwise:
* - create new socket udp_splice_map[V4][5000].ns_conn_sock
* - connect in namespace to 127.0.0.1:80 (note: this destination port
* might be remapped to another port instead)
* - get source port of new connected socket (10000) with getsockname()
* - add to epoll with reference: index = 10000, splice: UDP_BACK_TO_INIT
* - set udp_splice_map[V4][10000].init_bound_sock to s
* - set udp_splice_map[V4][10000].init_dst_port to 5000
* - update udp_splice_map[V4][5000].ns_conn_ts with current time
*
* - reverse direction: 127.0.0.1:80 -> 127.0.0.1:10000 in namespace from
* connected socket s, having epoll reference: index = 10000,
* splice = UDP_BACK_TO_INIT
* - if udp_splice_map[V4][10000].init_bound_sock:
* - send to udp_splice_map[V4][10000].init_bound_sock, with destination
* port udp_splice_map[V4][10000].init_dst_port (5000)
* - otherwise, discard
*
* - from namespace to init:
*
* - forward direction: 127.0.0.1:2000 -> 127.0.0.1:22 in namespace from bound
* socket s, with epoll reference: index = 22, splice = UDP_TO_INIT
* - if udp4_splice_map[V4][2000].init_conn_sock:
* - send packet to udp4_splice_map[2000].init_conn_sock
* - otherwise:
* - create new socket udp_splice_map[V4][2000].init_conn_sock
* - connect in init to 127.0.0.1:22 (note: this destination port
* might be remapped to another port instead)
* - get source port of new connected socket (4000) with getsockname()
* - add to epoll with reference: index = 4000, splice = UDP_BACK_TO_NS
* - set udp_splice_map[V4][4000].ns_bound_sock to s
* - set udp_splice_map[V4][4000].ns_dst_port to 2000
* - update udp_splice_map[V4][4000].init_conn_ts with current time
*
* - reverse direction: 127.0.0.1:22 -> 127.0.0.1:4000 in init from connected
* socket s, having epoll reference: index = 4000, splice = UDP_BACK_TO_NS
* - if udp_splice_map[V4][4000].ns_bound_sock:
* - send to udp_splice_map[V4][4000].ns_bound_sock, with destination port
* udp_splice_map[4000].ns_dst_port (2000)
* - otherwise, discard
*/
#include <sched.h>
#include <stdio.h>
#include <errno.h>
#include <limits.h>
#include <net/ethernet.h>
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include <sys/epoll.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <unistd.h>
#include <time.h>
#include <assert.h>
#include "checksum.h"
#include "util.h"
#include "passt.h"
#include "tap.h"
#include "pcap.h"
#define UDP_CONN_TIMEOUT 180 /* s, timeout for ephemeral or local bind */
#define UDP_SPLICE_FRAMES 32
#define UDP_TAP_FRAMES_MEM 32
#define UDP_TAP_FRAMES (c->mode == MODE_PASST ? UDP_TAP_FRAMES_MEM : 1)
/**
* struct udp_tap_port - Port tracking based on tap-facing source port
* @sock: Socket bound to source port used as index
* @flags: Flags for local bind, loopback address/unicast address as source
* @ts: Activity timestamp from tap, used for socket aging
*/
struct udp_tap_port {
int sock;
uint8_t flags;
#define PORT_LOCAL BIT(0)
#define PORT_LOOPBACK BIT(1)
#define PORT_GUA BIT(2)
time_t ts;
};
/**
* struct udp_splice_port - Source port tracking for traffic between namespaces
* @ns_conn_sock: Socket connected in namespace for init source port
* @init_conn_sock: Socket connected in init for namespace source port
* @ns_conn_ts: Timestamp of activity for socket connected in namespace
* @init_conn_ts: Timestamp of activity for socket connceted in init
* @ns_dst_port: Destination port in namespace for init source port
* @init_dst_port: Destination port in init for namespace source port
* @ns_bound_sock: Bound socket in namespace for this source port in init
* @init_bound_sock: Bound socket in init for this source port in namespace
*/
struct udp_splice_port {
int ns_conn_sock;
int init_conn_sock;
time_t ns_conn_ts;
time_t init_conn_ts;
in_port_t ns_dst_port;
in_port_t init_dst_port;
int ns_bound_sock;
int init_bound_sock;
};
/* Port tracking, arrays indexed by packet source port (host order) */
static struct udp_tap_port udp_tap_map [IP_VERSIONS][USHRT_MAX];
static struct udp_splice_port udp_splice_map [IP_VERSIONS][USHRT_MAX];
enum udp_act_type {
UDP_ACT_TAP,
UDP_ACT_NS_CONN,
UDP_ACT_INIT_CONN,
UDP_ACT_TYPE_MAX,
};
/* Activity-based aging for bindings */
static uint8_t udp_act[IP_VERSIONS][UDP_ACT_TYPE_MAX][(USHRT_MAX + 1) / 8];
/* Static buffers */
/**
* udp4_l2_buf_t - Pre-cooked IPv4 packet buffers for tap connections
* @s_in: Source socket address, filled in by recvmmsg()
* @psum: Partial IP header checksum (excluding tot_len and saddr)
* @vnet_len: 4-byte qemu vnet buffer length descriptor, only for passt mode
* @eh: Pre-filled Ethernet header
* @iph: Pre-filled IP header (except for tot_len and saddr)
* @uh: Headroom for UDP header
* @data: Storage for UDP payload
*/
static struct udp4_l2_buf_t {
struct sockaddr_in s_in;
uint32_t psum;
uint32_t vnet_len;
struct ethhdr eh;
struct iphdr iph;
struct udphdr uh;
uint8_t data[USHRT_MAX -
(sizeof(struct iphdr) + sizeof(struct udphdr))];
} __attribute__ ((packed, aligned(__alignof__(unsigned int))))
udp4_l2_buf[UDP_TAP_FRAMES_MEM];
/**
* udp6_l2_buf_t - Pre-cooked IPv6 packet buffers for tap connections
* @s_in6: Source socket address, filled in by recvmmsg()
* @vnet_len: 4-byte qemu vnet buffer length descriptor, only for passt mode
* @eh: Pre-filled Ethernet header
* @ip6h: Pre-filled IP header (except for payload_len and addresses)
* @uh: Headroom for UDP header
* @data: Storage for UDP payload
*/
struct udp6_l2_buf_t {
struct sockaddr_in6 s_in6;
#ifdef __AVX2__
/* Align ip6h to 32-byte boundary. */
uint8_t pad[64 - (sizeof(struct sockaddr_in6) + sizeof(struct ethhdr) +
sizeof(uint32_t))];
#endif
uint32_t vnet_len;
struct ethhdr eh;
struct ipv6hdr ip6h;
struct udphdr uh;
uint8_t data[USHRT_MAX -
(sizeof(struct ipv6hdr) + sizeof(struct udphdr))];
#ifdef __AVX2__
} __attribute__ ((packed, aligned(32)))
#else
} __attribute__ ((packed, aligned(__alignof__(unsigned int))))
#endif
udp6_l2_buf[UDP_TAP_FRAMES_MEM];
static struct sockaddr_storage udp_splice_namebuf;
static uint8_t udp_splice_buf[UDP_SPLICE_FRAMES][USHRT_MAX];
/* recvmmsg()/sendmmsg() data for tap */
static struct iovec udp4_l2_iov_sock [UDP_TAP_FRAMES_MEM];
static struct iovec udp6_l2_iov_sock [UDP_TAP_FRAMES_MEM];
static struct iovec udp4_l2_iov_tap [UDP_TAP_FRAMES_MEM];
static struct iovec udp6_l2_iov_tap [UDP_TAP_FRAMES_MEM];
static struct mmsghdr udp4_l2_mh_sock [UDP_TAP_FRAMES_MEM];
static struct mmsghdr udp6_l2_mh_sock [UDP_TAP_FRAMES_MEM];
static struct mmsghdr udp4_l2_mh_tap [UDP_TAP_FRAMES_MEM];
static struct mmsghdr udp6_l2_mh_tap [UDP_TAP_FRAMES_MEM];
/* recvmmsg()/sendmmsg() data for "spliced" connections */
static struct iovec udp_iov_recv [UDP_SPLICE_FRAMES];
static struct mmsghdr udp_mmh_recv [UDP_SPLICE_FRAMES];
static struct iovec udp_iov_send [UDP_SPLICE_FRAMES];
static struct mmsghdr udp_mmh_send [UDP_SPLICE_FRAMES];
static struct iovec udp_iov_sendto [UDP_SPLICE_FRAMES];
static struct mmsghdr udp_mmh_sendto [UDP_SPLICE_FRAMES];
/**
* udp_invert_portmap() - Compute reverse port translations for return packets
* @fwd: Port forwarding configuration to compute reverse map for
*/
static void udp_invert_portmap(struct udp_port_fwd *fwd)
{
int i;
assert(ARRAY_SIZE(fwd->f.delta) == ARRAY_SIZE(fwd->rdelta));
for (i = 0; i < ARRAY_SIZE(fwd->f.delta); i++) {
in_port_t delta = fwd->f.delta[i];
if (delta)
fwd->rdelta[(in_port_t)i + delta] = USHRT_MAX - delta;
}
}
/**
* udp_update_check4() - Update checksum with variable parts from stored one
* @buf: L2 packet buffer with final IPv4 header
*/
static void udp_update_check4(struct udp4_l2_buf_t *buf)
{
uint32_t sum = buf->psum;
sum += buf->iph.tot_len;
sum += (buf->iph.saddr >> 16) & 0xffff;
sum += buf->iph.saddr & 0xffff;
buf->iph.check = (uint16_t)~csum_fold(sum);
}
/**
* udp_update_l2_buf() - Update L2 buffers with Ethernet and IPv4 addresses
* @eth_d: Ethernet destination address, NULL if unchanged
* @eth_s: Ethernet source address, NULL if unchanged
* @ip_da: Pointer to IPv4 destination address, NULL if unchanged
*/
void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s,
const uint32_t *ip_da)
{
int i;
for (i = 0; i < UDP_TAP_FRAMES_MEM; i++) {
struct udp4_l2_buf_t *b4 = &udp4_l2_buf[i];
struct udp6_l2_buf_t *b6 = &udp6_l2_buf[i];
if (eth_d) {
memcpy(b4->eh.h_dest, eth_d, ETH_ALEN);
memcpy(b6->eh.h_dest, eth_d, ETH_ALEN);
}
if (eth_s) {
memcpy(b4->eh.h_source, eth_s, ETH_ALEN);
memcpy(b6->eh.h_source, eth_s, ETH_ALEN);
}
if (ip_da) {
b4->iph.daddr = *ip_da;
if (!i) {
b4->iph.saddr = 0;
b4->iph.tot_len = 0;
b4->iph.check = 0;
b4->psum = sum_16b(&b4->iph, 20);
} else {
b4->psum = udp4_l2_buf[0].psum;
}
}
}
}
/**
* udp_sock4_iov_init() - Initialise scatter-gather L2 buffers for IPv4 sockets
*/
static void udp_sock4_iov_init(void)
{
struct mmsghdr *h;
int i;
for (i = 0; i < ARRAY_SIZE(udp4_l2_buf); i++) {
udp4_l2_buf[i] = (struct udp4_l2_buf_t) {
{ 0 }, 0, 0,
L2_BUF_ETH_IP4_INIT, L2_BUF_IP4_INIT(IPPROTO_UDP),
{{{ 0 }}}, { 0 },
};
}
for (i = 0, h = udp4_l2_mh_sock; i < UDP_TAP_FRAMES_MEM; i++, h++) {
struct msghdr *mh = &h->msg_hdr;
mh->msg_name = &udp4_l2_buf[i].s_in;
mh->msg_namelen = sizeof(udp4_l2_buf[i].s_in);
udp4_l2_iov_sock[i].iov_base = udp4_l2_buf[i].data;
udp4_l2_iov_sock[i].iov_len = sizeof(udp4_l2_buf[i].data);
mh->msg_iov = &udp4_l2_iov_sock[i];
mh->msg_iovlen = 1;
}
for (i = 0, h = udp4_l2_mh_tap; i < UDP_TAP_FRAMES_MEM; i++, h++) {
struct msghdr *mh = &h->msg_hdr;
udp4_l2_iov_tap[i].iov_base = &udp4_l2_buf[i].vnet_len;
mh->msg_iov = &udp4_l2_iov_tap[i];
mh->msg_iovlen = 1;
}
}
/**
* udp_sock6_iov_init() - Initialise scatter-gather L2 buffers for IPv6 sockets
*/
static void udp_sock6_iov_init(void)
{
struct mmsghdr *h;
int i;
for (i = 0; i < ARRAY_SIZE(udp6_l2_buf); i++) {
udp6_l2_buf[i] = (struct udp6_l2_buf_t) {
{ 0 },
#ifdef __AVX2__
{ 0 },
#endif
0, L2_BUF_ETH_IP6_INIT, L2_BUF_IP6_INIT(IPPROTO_UDP),
{{{ 0 }}}, { 0 },
};
}
for (i = 0, h = udp6_l2_mh_sock; i < UDP_TAP_FRAMES_MEM; i++, h++) {
struct msghdr *mh = &h->msg_hdr;
mh->msg_name = &udp6_l2_buf[i].s_in6;
mh->msg_namelen = sizeof(struct sockaddr_in6);
udp6_l2_iov_sock[i].iov_base = udp6_l2_buf[i].data;
udp6_l2_iov_sock[i].iov_len = sizeof(udp6_l2_buf[i].data);
mh->msg_iov = &udp6_l2_iov_sock[i];
mh->msg_iovlen = 1;
}
for (i = 0, h = udp6_l2_mh_tap; i < UDP_TAP_FRAMES_MEM; i++, h++) {
struct msghdr *mh = &h->msg_hdr;
udp6_l2_iov_tap[i].iov_base = &udp6_l2_buf[i].vnet_len;
mh->msg_iov = &udp6_l2_iov_tap[i];
mh->msg_iovlen = 1;
}
}
/**
* udp_splice_connect() - Create and connect socket for "spliced" binding
* @c: Execution context
* @v6: Set for IPv6 connections
* @bound_sock: Originating bound socket
* @src: Source port of original connection, host order
* @dst: Destination port of original connection, host order
* @splice: UDP_BACK_TO_INIT from init, UDP_BACK_TO_NS from namespace
*
* Return: connected socket, negative error code on failure
*
* #syscalls:pasta getsockname
*/
int udp_splice_connect(const struct ctx *c, int v6, int bound_sock,
in_port_t src, in_port_t dst, int splice)
{
struct epoll_event ev = { .events = EPOLLIN | EPOLLRDHUP | EPOLLHUP };
union epoll_ref ref = { .r.proto = IPPROTO_UDP,
.r.p.udp.udp = { .splice = splice, .v6 = v6 }
};
struct sockaddr_storage sa;
struct udp_splice_port *sp;
socklen_t sl = sizeof(sa);
int s;
s = socket(v6 ? AF_INET6 : AF_INET, SOCK_DGRAM | SOCK_NONBLOCK,
IPPROTO_UDP);
if (s > SOCKET_MAX) {
close(s);
return -EIO;
}
if (s < 0)
return s;
ref.r.s = s;
if (v6) {
struct sockaddr_in6 addr6 = {
.sin6_family = AF_INET6,
.sin6_port = htons(dst),
.sin6_addr = IN6ADDR_LOOPBACK_INIT,
};
if (connect(s, (struct sockaddr *)&addr6, sizeof(addr6)))
goto fail;
} else {
struct sockaddr_in addr4 = {
.sin_family = AF_INET,
.sin_port = htons(dst),
.sin_addr = { .s_addr = htonl(INADDR_LOOPBACK) },
};
if (connect(s, (struct sockaddr *)&addr4, sizeof(addr4)))
goto fail;
}
if (getsockname(s, (struct sockaddr *)&sa, &sl))
goto fail;
if (v6) {
struct sockaddr_in6 sa6;
memcpy(&sa6, &sa, sizeof(sa6));
ref.r.p.udp.udp.port = ntohs(sa6.sin6_port);
} else {
struct sockaddr_in sa4;
memcpy(&sa4, &sa, sizeof(sa4));
ref.r.p.udp.udp.port = ntohs(sa4.sin_port);
}
sp = &udp_splice_map[v6 ? V6 : V4][ref.r.p.udp.udp.port];
if (splice == UDP_BACK_TO_INIT) {
sp->init_bound_sock = bound_sock;
sp->init_dst_port = src;
udp_splice_map[v6 ? V6 : V4][src].ns_conn_sock = s;
bitmap_set(udp_act[v6 ? V6 : V4][UDP_ACT_NS_CONN], src);
} else if (splice == UDP_BACK_TO_NS) {
sp->ns_bound_sock = bound_sock;
sp->ns_dst_port = src;
udp_splice_map[v6 ? V6 : V4][src].init_conn_sock = s;
bitmap_set(udp_act[v6 ? V6 : V4][UDP_ACT_INIT_CONN], src);
}
ev.data.u64 = ref.u64;
epoll_ctl(c->epollfd, EPOLL_CTL_ADD, s, &ev);
return s;
fail:
close(s);
return -1;
}
/**
* struct udp_splice_connect_ns_arg - Arguments for udp_splice_connect_ns()
* @c: Execution context
* @v6: Set for inbound IPv6 connection
* @bound_sock: Originating bound socket
* @src: Source port of original connection, host order
* @dst: Destination port of original connection, host order
* @s: Newly created socket or negative error code
*/
struct udp_splice_connect_ns_arg {
const struct ctx *c;
int v6;
int bound_sock;
in_port_t src;
in_port_t dst;
int s;
};
/**
* udp_splice_connect_ns() - Enter namespace and call udp_splice_connect()
* @arg: See struct udp_splice_connect_ns_arg
*
* Return: 0
*/
static int udp_splice_connect_ns(void *arg)
{
struct udp_splice_connect_ns_arg *a;
a = (struct udp_splice_connect_ns_arg *)arg;
if (ns_enter(a->c))
return 0;
a->s = udp_splice_connect(a->c, a->v6, a->bound_sock, a->src, a->dst,
UDP_BACK_TO_INIT);
return 0;
}
/**
* udp_sock_handler_splice() - Handler for socket mapped to "spliced" connection
* @c: Execution context
* @ref: epoll reference
* @events: epoll events bitmap
* @now: Current timestamp
*/
static void udp_sock_handler_splice(const struct ctx *c, union epoll_ref ref,
uint32_t events, const struct timespec *now)
{
in_port_t src, dst = ref.r.p.udp.udp.port, send_dst = 0;
struct msghdr *mh = &udp_mmh_recv[0].msg_hdr;
struct sockaddr_storage *sa_s = mh->msg_name;
int s, v6 = ref.r.p.udp.udp.v6, n, i;
if (!(events & EPOLLIN))
return;
n = recvmmsg(ref.r.s, udp_mmh_recv, UDP_SPLICE_FRAMES, 0, NULL);
if (n <= 0)
return;
if (v6) {
struct sockaddr_in6 *sa = (struct sockaddr_in6 *)sa_s;
src = htons(sa->sin6_port);
} else {
struct sockaddr_in *sa = (struct sockaddr_in *)sa_s;
src = ntohs(sa->sin_port);
}
switch (ref.r.p.udp.udp.splice) {
case UDP_TO_NS:
src += c->udp.fwd_out.rdelta[src];
if (!(s = udp_splice_map[v6][src].ns_conn_sock)) {
struct udp_splice_connect_ns_arg arg = {
c, v6, ref.r.s, src, dst, -1,
};
NS_CALL(udp_splice_connect_ns, &arg);
if ((s = arg.s) < 0)
return;
}
udp_splice_map[v6][src].ns_conn_ts = now->tv_sec;
break;
case UDP_BACK_TO_INIT:
if (!(s = udp_splice_map[v6][dst].init_bound_sock))
return;
send_dst = udp_splice_map[v6][dst].init_dst_port;
break;
case UDP_TO_INIT:
src += c->udp.fwd_in.rdelta[src];
if (!(s = udp_splice_map[v6][src].init_conn_sock)) {
s = udp_splice_connect(c, v6, ref.r.s, src, dst,
UDP_BACK_TO_NS);
if (s < 0)
return;
}
udp_splice_map[v6][src].init_conn_ts = now->tv_sec;
break;
case UDP_BACK_TO_NS:
if (!(s = udp_splice_map[v6][dst].ns_bound_sock))
return;
send_dst = udp_splice_map[v6][dst].ns_dst_port;
break;
default:
return;
}
if (ref.r.p.udp.udp.splice == UDP_TO_NS ||
ref.r.p.udp.udp.splice == UDP_TO_INIT) {
for (i = 0; i < n; i++) {
struct msghdr *mh_s = &udp_mmh_send[i].msg_hdr;
mh_s->msg_iov->iov_len = udp_mmh_recv[i].msg_len;
}
sendmmsg(s, udp_mmh_send, n, MSG_NOSIGNAL);
return;
}
for (i = 0; i < n; i++) {
struct msghdr *mh_s = &udp_mmh_sendto[i].msg_hdr;
mh_s->msg_iov->iov_len = udp_mmh_recv[i].msg_len;
}
if (v6) {
*((struct sockaddr_in6 *)&udp_splice_namebuf) =
((struct sockaddr_in6) {
.sin6_family = AF_INET6,
.sin6_addr = IN6ADDR_LOOPBACK_INIT,
.sin6_port = htons(send_dst),
.sin6_scope_id = 0,
});
} else {
*((struct sockaddr_in *)&udp_splice_namebuf) =
((struct sockaddr_in) {
.sin_family = AF_INET,
.sin_addr = { .s_addr = htonl(INADDR_LOOPBACK) },
.sin_port = htons(send_dst),
.sin_zero = { 0 },
});
}
sendmmsg(s, udp_mmh_sendto, n, MSG_NOSIGNAL);
}
/**
* udp_sock_fill_data_v4() - Fill and queue one buffer. In pasta mode, write it
* @c: Execution context
* @n: Index of buffer in udp4_l2_buf pool
* @ref: epoll reference from socket
* @msg_idx: Index within message being prepared (spans multiple buffers)
* @msg_len: Length of current message being prepared for sending
* @now: Current timestamp
*/
static void udp_sock_fill_data_v4(const struct ctx *c, int n,
union epoll_ref ref,
int *msg_idx, int *msg_bufs, ssize_t *msg_len,
const struct timespec *now)
{
struct msghdr *mh = &udp6_l2_mh_tap[*msg_idx].msg_hdr;
struct udp4_l2_buf_t *b = &udp4_l2_buf[n];
size_t ip_len, buf_len;
in_port_t src_port;
in_addr_t src;
ip_len = udp4_l2_mh_sock[n].msg_len + sizeof(b->iph) + sizeof(b->uh);
b->iph.tot_len = htons(ip_len);
src = ntohl(b->s_in.sin_addr.s_addr);
src_port = htons(b->s_in.sin_port);
if (src >> IN_CLASSA_NSHIFT == IN_LOOPBACKNET ||
src == INADDR_ANY || src == ntohl(c->ip4.addr_seen)) {
b->iph.saddr = c->ip4.gw;
udp_tap_map[V4][src_port].ts = now->tv_sec;
udp_tap_map[V4][src_port].flags |= PORT_LOCAL;
if (b->s_in.sin_addr.s_addr == c->ip4.addr_seen)
udp_tap_map[V4][src_port].flags &= ~PORT_LOOPBACK;
else
udp_tap_map[V4][src_port].flags |= PORT_LOOPBACK;
bitmap_set(udp_act[V4][UDP_ACT_TAP], src_port);
} else if (c->ip4.dns_fwd &&
src == ntohl(c->ip4.dns[0]) && ntohs(src_port) == 53) {
b->iph.saddr = c->ip4.dns_fwd;
} else {
b->iph.saddr = b->s_in.sin_addr.s_addr;
}
udp_update_check4(b);
b->uh.source = b->s_in.sin_port;
b->uh.dest = htons(ref.r.p.udp.udp.port);
b->uh.len = htons(udp4_l2_mh_sock[n].msg_len + sizeof(b->uh));
if (c->mode == MODE_PASTA) {
PRAGMA_STRINGOP_OVERREAD_IGNORE
if (write(c->fd_tap, &b->eh, sizeof(b->eh) + ip_len) < 0)
debug("tap write: %s", strerror(errno));
PRAGMA_STRINGOP_OVERREAD_IGNORE_POP
pcap((char *)&b->eh, sizeof(b->eh) + ip_len);
return;
}
b->vnet_len = htonl(ip_len + sizeof(struct ethhdr));
buf_len = sizeof(uint32_t) + sizeof(struct ethhdr) + ip_len;
udp4_l2_iov_tap[n].iov_len = buf_len;
/* With bigger messages, qemu closes the connection. */
if (*msg_bufs && *msg_len + buf_len > SHRT_MAX) {
mh->msg_iovlen = *msg_bufs;
(*msg_idx)++;
udp4_l2_mh_tap[*msg_idx].msg_hdr.msg_iov = &udp4_l2_iov_tap[n];
*msg_len = *msg_bufs = 0;
}
*msg_len += buf_len;
(*msg_bufs)++;
}
/**
* udp_sock_fill_data_v4() - Fill and queue one buffer. In pasta mode, write it
* @c: Execution context
* @n: Index of buffer in udp4_l2_buf pool
* @ref: epoll reference from socket
* @msg_idx: Index within message being prepared (spans multiple buffers)
* @msg_len: Length of current message being prepared for sending
* @now: Current timestamp
*/
static void udp_sock_fill_data_v6(const struct ctx *c, int n,
union epoll_ref ref,
int *msg_idx, int *msg_bufs, ssize_t *msg_len,
const struct timespec *now)
{
struct msghdr *mh = &udp6_l2_mh_tap[*msg_idx].msg_hdr;
struct udp6_l2_buf_t *b = &udp6_l2_buf[n];
size_t ip_len, buf_len;
struct in6_addr *src;
in_port_t src_port;
src = &b->s_in6.sin6_addr;
src_port = ntohs(b->s_in6.sin6_port);
ip_len = udp6_l2_mh_sock[n].msg_len + sizeof(b->ip6h) + sizeof(b->uh);
b->ip6h.payload_len = htons(udp6_l2_mh_sock[n].msg_len + sizeof(b->uh));
if (IN6_IS_ADDR_LINKLOCAL(src)) {
b->ip6h.daddr = c->ip6.addr_ll_seen;
b->ip6h.saddr = b->s_in6.sin6_addr;
} else if (IN6_IS_ADDR_LOOPBACK(src) ||
IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr_seen) ||
IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr)) {
b->ip6h.daddr = c->ip6.addr_ll_seen;
if (IN6_IS_ADDR_LINKLOCAL(&c->ip6.gw))
b->ip6h.saddr = c->ip6.gw;
else
b->ip6h.saddr = c->ip6.addr_ll;
udp_tap_map[V6][src_port].ts = now->tv_sec;
udp_tap_map[V6][src_port].flags |= PORT_LOCAL;
if (IN6_IS_ADDR_LOOPBACK(src))
udp_tap_map[V6][src_port].flags |= PORT_LOOPBACK;
else
udp_tap_map[V6][src_port].flags &= ~PORT_LOOPBACK;
if (IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr))
udp_tap_map[V6][src_port].flags |= PORT_GUA;
else
udp_tap_map[V6][src_port].flags &= ~PORT_GUA;
bitmap_set(udp_act[V6][UDP_ACT_TAP], src_port);
} else if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_fwd) &&
IN6_ARE_ADDR_EQUAL(src, &c->ip6.dns_fwd) && src_port == 53) {
b->ip6h.daddr = c->ip6.addr_seen;
b->ip6h.saddr = c->ip6.dns_fwd;
} else {
b->ip6h.daddr = c->ip6.addr_seen;
b->ip6h.saddr = b->s_in6.sin6_addr;
}
b->uh.source = b->s_in6.sin6_port;
b->uh.dest = htons(ref.r.p.udp.udp.port);
b->uh.len = b->ip6h.payload_len;
b->ip6h.hop_limit = IPPROTO_UDP;
b->ip6h.version = b->ip6h.nexthdr = b->uh.check = 0;
b->uh.check = csum(&b->ip6h, ip_len, 0);
b->ip6h.version = 6;
b->ip6h.nexthdr = IPPROTO_UDP;
b->ip6h.hop_limit = 255;
if (c->mode == MODE_PASTA) {
PRAGMA_STRINGOP_OVERREAD_IGNORE
if (write(c->fd_tap, &b->eh, sizeof(b->eh) + ip_len) < 0)
debug("tap write: %s", strerror(errno));
PRAGMA_STRINGOP_OVERREAD_IGNORE_POP
pcap((char *)&b->eh, sizeof(b->eh) + ip_len);
return;
}
b->vnet_len = htonl(ip_len + sizeof(struct ethhdr));
buf_len = sizeof(uint32_t) + sizeof(struct ethhdr) + ip_len;
udp6_l2_iov_tap[n].iov_len = buf_len;
/* With bigger messages, qemu closes the connection. */
if (*msg_bufs && *msg_len + buf_len > SHRT_MAX) {
mh->msg_iovlen = *msg_bufs;
(*msg_idx)++;
udp6_l2_mh_tap[*msg_idx].msg_hdr.msg_iov = &udp6_l2_iov_tap[n];
*msg_len = *msg_bufs = 0;
}
*msg_len += buf_len;
(*msg_bufs)++;
}
/**
* udp_sock_handler() - Handle new data from socket
* @c: Execution context
* @ref: epoll reference
* @events: epoll events bitmap
* @now: Current timestamp
*
* #syscalls recvmmsg
* #syscalls:passt sendmmsg sendmsg
*/
void udp_sock_handler(const struct ctx *c, union epoll_ref ref, uint32_t events,
const struct timespec *now)
{
ssize_t n, msg_len = 0, missing = 0;
int msg_bufs = 0, msg_i = 0, ret;
struct mmsghdr *tap_mmh;
struct msghdr *last_mh;
unsigned int i;
if (events == EPOLLERR)
return;
if (ref.r.p.udp.udp.splice) {
udp_sock_handler_splice(c, ref, events, now);
return;
}
if (ref.r.p.udp.udp.v6) {
n = recvmmsg(ref.r.s, udp6_l2_mh_sock, UDP_TAP_FRAMES, 0, NULL);
if (n <= 0)
return;
udp6_l2_mh_tap[0].msg_hdr.msg_iov = &udp6_l2_iov_tap[0];
for (i = 0; i < (unsigned)n; i++) {
udp_sock_fill_data_v6(c, i, ref,
&msg_i, &msg_bufs, &msg_len, now);
}
udp6_l2_mh_tap[msg_i].msg_hdr.msg_iovlen = msg_bufs;
tap_mmh = udp6_l2_mh_tap;
} else {
n = recvmmsg(ref.r.s, udp4_l2_mh_sock, UDP_TAP_FRAMES, 0, NULL);
if (n <= 0)
return;
udp6_l2_mh_tap[0].msg_hdr.msg_iov = &udp6_l2_iov_tap[0];
for (i = 0; i < (unsigned)n; i++) {
udp_sock_fill_data_v4(c, i, ref,
&msg_i, &msg_bufs, &msg_len, now);
}
udp4_l2_mh_tap[msg_i].msg_hdr.msg_iovlen = msg_bufs;
tap_mmh = udp4_l2_mh_tap;
}
if (c->mode == MODE_PASTA)
return;
ret = sendmmsg(c->fd_tap, tap_mmh, msg_i + 1,
MSG_NOSIGNAL | MSG_DONTWAIT);
if (ret <= 0)
return;
/* If we lose some messages to sendmmsg() here, fine, it's UDP. However,
* the last message needs to be delivered completely, otherwise qemu
* will fail to reassemble the next message and close the connection. Go
* through headers from the last sent message, counting bytes, and, if
* and as soon as we see more bytes than sendmmsg() sent, re-send the
* rest with a blocking call.
*
* In pictures, given this example:
*
* iov #0 iov #1 iov #2 iov #3
* tap_mmh[ret - 1].msg_hdr: .... ...... ..... ......
* tap_mmh[ret - 1].msg_len: 7 .... ...
*
* when 'msglen' reaches: 10 ^
* and 'missing' below is: 3 ---
*
* re-send everything from here: ^-- ----- ------
*/
last_mh = &tap_mmh[ret - 1].msg_hdr;
for (i = 0, msg_len = 0; i < last_mh->msg_iovlen; i++) {
if (missing <= 0) {
msg_len += last_mh->msg_iov[i].iov_len;
missing = msg_len - tap_mmh[ret - 1].msg_len;
}
if (missing > 0) {
uint8_t **iov_base;
int first_offset;
iov_base = (uint8_t **)&last_mh->msg_iov[i].iov_base;
first_offset = last_mh->msg_iov[i].iov_len - missing;
*iov_base += first_offset;
last_mh->msg_iov[i].iov_len = missing;
last_mh->msg_iov = &last_mh->msg_iov[i];
if (sendmsg(c->fd_tap, last_mh, MSG_NOSIGNAL) < 0)
debug("UDP: %li bytes to tap missing", missing);
*iov_base -= first_offset;
break;
}
}
pcapmm(tap_mmh, ret);
}
/**
* udp_tap_handler() - Handle packets from tap
* @c: Execution context
* @af: Address family, AF_INET or AF_INET6
* @addr: Destination address
* @p: Pool of UDP packets, with UDP headers
* @now: Current timestamp
*
* Return: count of consumed packets
*
* #syscalls sendmmsg
*/
int udp_tap_handler(struct ctx *c, int af, const void *addr,
const struct pool *p, const struct timespec *now)
{
struct mmsghdr mm[UIO_MAXIOV];
struct iovec m[UIO_MAXIOV];
struct sockaddr_in6 s_in6;
struct sockaddr_in s_in;
struct sockaddr *sa;
int i, s, count = 0;
in_port_t src, dst;
struct udphdr *uh;
socklen_t sl;
(void)c;
uh = packet_get(p, 0, 0, sizeof(*uh), NULL);
if (!uh)
return 1;
/* The caller already checks that all the messages have the same source
* and destination, so we can just take those from the first message.
*/
src = ntohs(uh->source);
dst = ntohs(uh->dest);
if (af == AF_INET) {
s_in = (struct sockaddr_in) {
.sin_family = AF_INET,
.sin_port = uh->dest,
.sin_addr = *(struct in_addr *)addr,
};
sa = (struct sockaddr *)&s_in;
sl = sizeof(s_in);
if (!(s = udp_tap_map[V4][src].sock)) {
union udp_epoll_ref uref = { .udp.bound = 1,
.udp.port = src };
s = sock_l4(c, AF_INET, IPPROTO_UDP, NULL, src,
uref.u32);
if (s < 0)
return p->count;
udp_tap_map[V4][src].sock = s;
bitmap_set(udp_act[V4][UDP_ACT_TAP], src);
}
udp_tap_map[V4][src].ts = now->tv_sec;
if (s_in.sin_addr.s_addr == c->ip4.gw && !c->no_map_gw) {
if (!(udp_tap_map[V4][dst].flags & PORT_LOCAL) ||
(udp_tap_map[V4][dst].flags & PORT_LOOPBACK))
s_in.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
else
s_in.sin_addr.s_addr = c->ip4.addr_seen;
} else if (s_in.sin_addr.s_addr == c->ip4.dns_fwd &&
ntohs(s_in.sin_port) == 53) {
s_in.sin_addr.s_addr = c->ip4.dns[0];
}
} else {
s_in6 = (struct sockaddr_in6) {
.sin6_family = AF_INET6,
.sin6_port = uh->dest,
.sin6_addr = *(struct in6_addr *)addr,
};
const void *bind_addr = &in6addr_any;
sa = (struct sockaddr *)&s_in6;
sl = sizeof(s_in6);
if (IN6_ARE_ADDR_EQUAL(addr, &c->ip6.gw) && !c->no_map_gw) {
if (!(udp_tap_map[V6][dst].flags & PORT_LOCAL) ||
(udp_tap_map[V6][dst].flags & PORT_LOOPBACK))
s_in6.sin6_addr = in6addr_loopback;
else if (udp_tap_map[V6][dst].flags & PORT_GUA)
s_in6.sin6_addr = c->ip6.addr;
else
s_in6.sin6_addr = c->ip6.addr_seen;
} else if (IN6_ARE_ADDR_EQUAL(addr, &c->ip6.dns_fwd) &&
ntohs(s_in6.sin6_port) == 53) {
s_in6.sin6_addr = c->ip6.dns[0];
} else if (IN6_IS_ADDR_LINKLOCAL(&s_in6.sin6_addr)) {
bind_addr = &c->ip6.addr_ll;
}
if (!(s = udp_tap_map[V6][src].sock)) {
union udp_epoll_ref uref = { .udp.bound = 1,
.udp.v6 = 1,
.udp.port = src };
s = sock_l4(c, AF_INET6, IPPROTO_UDP, bind_addr, src,
uref.u32);
if (s < 0)
return p->count;
udp_tap_map[V6][src].sock = s;
bitmap_set(udp_act[V6][UDP_ACT_TAP], src);
}
udp_tap_map[V6][src].ts = now->tv_sec;
}
for (i = 0; i < (int)p->count; i++) {
struct udphdr *uh_send;
size_t len;
uh_send = packet_get(p, i, 0, sizeof(*uh), &len);
if (!uh_send)
return p->count;
mm[i].msg_hdr.msg_name = sa;
mm[i].msg_hdr.msg_namelen = sl;
if (len) {
m[i].iov_base = (char *)(uh_send + 1);
m[i].iov_len = len;
mm[i].msg_hdr.msg_iov = m + i;
mm[i].msg_hdr.msg_iovlen = 1;
} else {
mm[i].msg_hdr.msg_iov = NULL;
mm[i].msg_hdr.msg_iovlen = 0;
}
mm[i].msg_hdr.msg_control = NULL;
mm[i].msg_hdr.msg_controllen = 0;
mm[i].msg_hdr.msg_flags = 0;
count++;
}
count = sendmmsg(s, mm, count, MSG_NOSIGNAL);
if (count < 0)
return 1;
return count;
}
/**
* udp_sock_init() - Initialise listening sockets for a given port
* @c: Execution context
* @ns: In pasta mode, if set, bind with loopback address in namespace
* @af: Address family to select a specific IP version, or AF_UNSPEC
* @addr: Pointer to address for binding, NULL if not configured
* @port: Port, host order
*/
void udp_sock_init(const struct ctx *c, int ns, sa_family_t af,
const void *addr, in_port_t port)
{
union udp_epoll_ref uref = { .udp.bound = 1 };
const void *bind_addr;
int s;
if (ns) {
uref.udp.port = (in_port_t)(port +
c->udp.fwd_out.f.delta[port]);
} else {
uref.udp.port = (in_port_t)(port +
c->udp.fwd_in.f.delta[port]);
}
if (af == AF_INET || af == AF_UNSPEC) {
if (!addr && c->mode == MODE_PASTA)
bind_addr = &c->ip4.addr;
else
bind_addr = addr;
uref.udp.v6 = 0;
if (!ns) {
uref.udp.splice = 0;
s = sock_l4(c, AF_INET, IPPROTO_UDP, bind_addr, port,
uref.u32);
udp_tap_map[V4][uref.udp.port].sock = s;
}
if (c->mode == MODE_PASTA) {
bind_addr = &(uint32_t){ htonl(INADDR_LOOPBACK) };
uref.udp.splice = UDP_TO_NS;
sock_l4(c, AF_INET, IPPROTO_UDP, bind_addr, port,
uref.u32);
}
if (ns) {
bind_addr = &(uint32_t){ htonl(INADDR_LOOPBACK) };
uref.udp.splice = UDP_TO_INIT;
sock_l4(c, AF_INET, IPPROTO_UDP, bind_addr, port,
uref.u32);
}
}
if (af == AF_INET6 || af == AF_UNSPEC) {
if (!addr && c->mode == MODE_PASTA)
bind_addr = &c->ip6.addr;
else
bind_addr = addr;
uref.udp.v6 = 1;
if (!ns) {
uref.udp.splice = 0;
s = sock_l4(c, AF_INET6, IPPROTO_UDP, bind_addr, port,
uref.u32);
udp_tap_map[V6][uref.udp.port].sock = s;
}
if (c->mode == MODE_PASTA) {
bind_addr = &in6addr_loopback;
uref.udp.splice = UDP_TO_NS;
sock_l4(c, AF_INET6, IPPROTO_UDP, bind_addr, port,
uref.u32);
}
if (ns) {
bind_addr = &in6addr_loopback;
uref.udp.splice = UDP_TO_INIT;
sock_l4(c, AF_INET6, IPPROTO_UDP, bind_addr, port,
uref.u32);
}
}
}
/**
* udp_sock_init_ns() - Bind sockets in namespace for inbound connections
* @arg: Execution context
*
* Return: 0
*/
int udp_sock_init_ns(void *arg)
{
struct ctx *c = (struct ctx *)arg;
unsigned dst;
if (ns_enter(c))
return 0;
for (dst = 0; dst < USHRT_MAX; dst++) {
if (!bitmap_isset(c->udp.fwd_out.f.map, dst))
continue;
udp_sock_init(c, 1, AF_UNSPEC, NULL, dst);
}
return 0;
}
/**
* udp_splice_iov_init() - Set up buffers and descriptors for recvmmsg/sendmmsg
*/
static void udp_splice_iov_init(void)
{
struct mmsghdr *h;
struct iovec *iov;
int i;
for (i = 0, h = udp_mmh_recv; i < UDP_SPLICE_FRAMES; i++, h++) {
struct msghdr *mh = &h->msg_hdr;
if (!i) {
mh->msg_name = &udp_splice_namebuf;
mh->msg_namelen = sizeof(udp_splice_namebuf);
}
mh->msg_iov = &udp_iov_recv[i];
mh->msg_iovlen = 1;
}
for (i = 0, iov = udp_iov_recv; i < UDP_SPLICE_FRAMES; i++, iov++) {
iov->iov_base = udp_splice_buf[i];
iov->iov_len = sizeof(udp_splice_buf[i]);
}
for (i = 0, h = udp_mmh_send; i < UDP_SPLICE_FRAMES; i++, h++) {
struct msghdr *mh = &h->msg_hdr;
mh->msg_iov = &udp_iov_send[i];
mh->msg_iovlen = 1;
}
for (i = 0, iov = udp_iov_send; i < UDP_SPLICE_FRAMES; i++, iov++)
iov->iov_base = udp_splice_buf[i];
for (i = 0, h = udp_mmh_sendto; i < UDP_SPLICE_FRAMES; i++, h++) {
struct msghdr *mh = &h->msg_hdr;
mh->msg_name = &udp_splice_namebuf;
mh->msg_namelen = sizeof(udp_splice_namebuf);
mh->msg_iov = &udp_iov_sendto[i];
mh->msg_iovlen = 1;
}
for (i = 0, iov = udp_iov_sendto; i < UDP_SPLICE_FRAMES; i++, iov++)
iov->iov_base = udp_splice_buf[i];
}
/**
* udp_init() - Initialise per-socket data, and sockets in namespace
* @c: Execution context
*
* Return: 0
*/
int udp_init(struct ctx *c)
{
if (c->ifi4)
udp_sock4_iov_init();
if (c->ifi6)
udp_sock6_iov_init();
udp_invert_portmap(&c->udp.fwd_in);
udp_invert_portmap(&c->udp.fwd_out);
if (c->mode == MODE_PASTA) {
udp_splice_iov_init();
NS_CALL(udp_sock_init_ns, c);
}
return 0;
}
/**
* udp_timer_one() - Handler for timed events on one port
* @c: Execution context
* @v6: Set for IPv6 connections
* @type: Socket type
* @port: Port number, host order
* @ts: Timestamp from caller
*/
static void udp_timer_one(struct ctx *c, int v6, enum udp_act_type type,
in_port_t port, const struct timespec *ts)
{
struct udp_splice_port *sp;
struct udp_tap_port *tp;
int s = -1;
switch (type) {
case UDP_ACT_TAP:
tp = &udp_tap_map[v6 ? V6 : V4][port];
if (ts->tv_sec - tp->ts > UDP_CONN_TIMEOUT) {
s = tp->sock;
tp->flags = 0;
}
break;
case UDP_ACT_INIT_CONN:
sp = &udp_splice_map[v6 ? V6 : V4][port];
if (ts->tv_sec - sp->init_conn_ts > UDP_CONN_TIMEOUT)
s = sp->init_conn_sock;
break;
case UDP_ACT_NS_CONN:
sp = &udp_splice_map[v6 ? V6 : V4][port];
if (ts->tv_sec - sp->ns_conn_ts > UDP_CONN_TIMEOUT)
s = sp->ns_conn_sock;
break;
default:
return;
}
if (s > 0) {
epoll_ctl(c->epollfd, EPOLL_CTL_DEL, s, NULL);
close(s);
bitmap_clear(udp_act[v6 ? V6 : V4][type], port);
}
}
/**
* udp_timer() - Scan activity bitmaps for ports with associated timed events
* @c: Execution context
* @ts: Timestamp from caller
*/
void udp_timer(struct ctx *c, const struct timespec *ts)
{
int n, t, v6 = 0;
unsigned int i;
long *word, tmp;
if (!c->ifi4)
v6 = 1;
v6:
for (t = 0; t < UDP_ACT_TYPE_MAX; t++) {
word = (long *)udp_act[v6 ? V6 : V4][t];
for (i = 0; i < ARRAY_SIZE(udp_act[0][0]);
i += sizeof(long), word++) {
tmp = *word;
while ((n = ffsl(tmp))) {
tmp &= ~(1UL << (n - 1));
udp_timer_one(c, v6, t, i * 8 + n - 1, ts);
}
}
}
if (!v6 && c->ifi6) {
v6 = 1;
goto v6;
}
}
Reference in a new issue View git blame Copy permalink