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passt/udp.c
Stefano Brivio ca2749e1bd passt: Relicense to GPL 2.0, or any later version 
In practical terms, passt doesn't benefit from the additional
protection offered by the AGPL over the GPL, because it's not
suitable to be executed over a computer network.

Further, restricting the distribution under the version 3 of the GPL
wouldn't provide any practical advantage either, as long as the passt
codebase is concerned, and might cause unnecessary compatibility
dilemmas.

Change licensing terms to the GNU General Public License Version 2,
or any later version, with written permission from all current and
past contributors, namely: myself, David Gibson, Laine Stump, Andrea
Bolognani, Paul Holzinger, Richard W.M. Jones, Chris Kuhn, Florian
Weimer, Giuseppe Scrivano, Stefan Hajnoczi, and Vasiliy Ulyanov.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2023-04-06 18:00:33 +02:00

1216 lines
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// SPDX-License-Identifier: GPL-2.0-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 socket s,
* with epoll reference: index = 80, splice = 1, orig = 1, ns = 0
* - if udp_splice_ns[V4][5000].sock:
* - send packet to udp_splice_ns[V4][5000].sock, with destination port
* 80
* - otherwise:
* - create new socket udp_splice_ns[V4][5000].sock
* - bind in namespace to 127.0.0.1:5000
* - add to epoll with reference: index = 5000, splice = 1, orig = 0,
* ns = 1
* - update udp_splice_init[V4][80].ts and udp_splice_ns[V4][5000].ts with
* current time
*
* - reverse direction: 127.0.0.1:80 -> 127.0.0.1:5000 in namespace socket s,
* having epoll reference: index = 5000, splice = 1, orig = 0, ns = 1
* - if udp_splice_init[V4][80].sock:
* - send to udp_splice_init[V4][80].sock, with destination port 5000
* - update udp_splice_init[V4][80].ts and udp_splice_ns[V4][5000].ts with
* current time
* - otherwise, discard
*
* - from namespace to init:
*
* - forward direction: 127.0.0.1:2000 -> 127.0.0.1:22 in namespace from
* socket s, with epoll reference: index = 22, splice = 1, orig = 1, ns = 1
* - if udp4_splice_init[V4][2000].sock:
* - send packet to udp_splice_init[V4][2000].sock, with destination
* port 22
* - otherwise:
* - create new socket udp_splice_init[V4][2000].sock
* - bind in init to 127.0.0.1:2000
* - add to epoll with reference: index = 2000, splice = 1, orig = 0,
* ns = 0
* - update udp_splice_ns[V4][22].ts and udp_splice_init[V4][2000].ts with
* current time
*
* - reverse direction: 127.0.0.1:22 -> 127.0.0.1:2000 in init from socket s,
* having epoll reference: index = 2000, splice = 1, orig = 0, ns = 0
* - if udp_splice_ns[V4][22].sock:
* - send to udp_splice_ns[V4][22].sock, with destination port 2000
* - update udp_splice_ns[V4][22].ts and udp_splice_init[V4][2000].ts with
* current time
* - otherwise, discard
*/
#include <sched.h>
#include <unistd.h>
#include <signal.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 <time.h>
#include "checksum.h"
#include "util.h"
#include "passt.h"
#include "tap.h"
#include "pcap.h"
#include "log.h"
#define UDP_CONN_TIMEOUT 180 /* s, timeout for ephemeral or local bind */
#define UDP_MAX_FRAMES 32 /* max # of frames to receive at once */
/**
* 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 - Bound socket for spliced communication
* @sock: Socket bound to index port
* @ts: Activity timestamp
*/
struct udp_splice_port {
int sock;
time_t ts;
};
/* Port tracking, arrays indexed by packet source port (host order) */
static struct udp_tap_port udp_tap_map [IP_VERSIONS][NUM_PORTS];
/* "Spliced" sockets indexed by bound port (host order) */
static struct udp_splice_port udp_splice_ns [IP_VERSIONS][NUM_PORTS];
static struct udp_splice_port udp_splice_init[IP_VERSIONS][NUM_PORTS];
enum udp_act_type {
UDP_ACT_TAP,
UDP_ACT_SPLICE_NS,
UDP_ACT_SPLICE_INIT,
UDP_ACT_TYPE_MAX,
};
/* Activity-based aging for bindings */
static uint8_t udp_act[IP_VERSIONS][UDP_ACT_TYPE_MAX][DIV_ROUND_UP(NUM_PORTS, 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)
* @taph: Tap-level headers (partially pre-filled)
* @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;
struct tap_hdr taph;
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_MAX_FRAMES];
/**
* udp6_l2_buf_t - Pre-cooked IPv6 packet buffers for tap connections
* @s_in6: Source socket address, filled in by recvmmsg()
* @taph: Tap-level headers (partially pre-filled)
* @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
struct tap_hdr taph;
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_MAX_FRAMES];
/* recvmmsg()/sendmmsg() data for tap */
static struct iovec udp4_l2_iov_sock [UDP_MAX_FRAMES];
static struct iovec udp6_l2_iov_sock [UDP_MAX_FRAMES];
static struct iovec udp4_l2_iov_tap [UDP_MAX_FRAMES];
static struct iovec udp6_l2_iov_tap [UDP_MAX_FRAMES];
static struct mmsghdr udp4_l2_mh_sock [UDP_MAX_FRAMES];
static struct mmsghdr udp6_l2_mh_sock [UDP_MAX_FRAMES];
/* recvmmsg()/sendmmsg() data for "spliced" connections */
static struct iovec udp4_iov_splice [UDP_MAX_FRAMES];
static struct iovec udp6_iov_splice [UDP_MAX_FRAMES];
static struct sockaddr_in udp4_localname = {
.sin_family = AF_INET,
.sin_addr = IN4ADDR_LOOPBACK_INIT,
};
static struct sockaddr_in6 udp6_localname = {
.sin6_family = AF_INET6,
.sin6_addr = IN6ADDR_LOOPBACK_INIT,
};
static struct mmsghdr udp4_mh_splice [UDP_MAX_FRAMES];
static struct mmsghdr udp6_mh_splice [UDP_MAX_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] = NUM_PORTS - 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 struct in_addr *ip_da)
{
int i;
for (i = 0; i < UDP_MAX_FRAMES; i++) {
struct udp4_l2_buf_t *b4 = &udp4_l2_buf[i];
struct udp6_l2_buf_t *b6 = &udp6_l2_buf[i];
tap_update_mac(&b4->taph, eth_d, eth_s);
tap_update_mac(&b6->taph, eth_d, eth_s);
if (ip_da) {
b4->iph.daddr = ip_da->s_addr;
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
* @c: Execution context
*/
static void udp_sock4_iov_init(const struct ctx *c)
{
struct mmsghdr *h;
int i;
for (i = 0; i < ARRAY_SIZE(udp4_l2_buf); i++) {
udp4_l2_buf[i] = (struct udp4_l2_buf_t) {
.taph = TAP_HDR_INIT(ETH_P_IP),
.iph = L2_BUF_IP4_INIT(IPPROTO_UDP)
};
}
for (i = 0, h = udp4_l2_mh_sock; i < UDP_MAX_FRAMES; 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; i < UDP_MAX_FRAMES; i++) {
struct iovec *iov = &udp4_l2_iov_tap[i];
iov->iov_base = tap_iov_base(c, &udp4_l2_buf[i].taph);
}
}
/**
* udp_sock6_iov_init() - Initialise scatter-gather L2 buffers for IPv6 sockets
* @c: Execution context
*/
static void udp_sock6_iov_init(const struct ctx *c)
{
struct mmsghdr *h;
int i;
for (i = 0; i < ARRAY_SIZE(udp6_l2_buf); i++) {
udp6_l2_buf[i] = (struct udp6_l2_buf_t) {
.taph = TAP_HDR_INIT(ETH_P_IPV6),
.ip6h = L2_BUF_IP6_INIT(IPPROTO_UDP)
};
}
for (i = 0, h = udp6_l2_mh_sock; i < UDP_MAX_FRAMES; 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; i < UDP_MAX_FRAMES; i++) {
struct iovec *iov = &udp6_l2_iov_tap[i];
iov->iov_base = tap_iov_base(c, &udp6_l2_buf[i].taph);
}
}
/**
* udp_splice_new() - Create and prepare socket for "spliced" binding
* @c: Execution context
* @v6: Set for IPv6 sockets
* @src: Source port of original connection, host order
* @splice: UDP_BACK_TO_INIT from init, UDP_BACK_TO_NS from namespace
*
* Return: prepared socket, negative error code on failure
*
* #syscalls:pasta getsockname
*/
int udp_splice_new(const struct ctx *c, int v6, in_port_t src, bool ns)
{
struct epoll_event ev = { .events = EPOLLIN | EPOLLRDHUP | EPOLLHUP };
union epoll_ref ref = { .r.proto = IPPROTO_UDP,
.r.p.udp.udp = { .splice = true, .ns = ns,
.v6 = v6, .port = src }
};
struct udp_splice_port *sp;
int act, s;
if (ns) {
sp = &udp_splice_ns[v6 ? V6 : V4][src];
act = UDP_ACT_SPLICE_NS;
} else {
sp = &udp_splice_init[v6 ? V6 : V4][src];
act = UDP_ACT_SPLICE_INIT;
}
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(src),
.sin6_addr = IN6ADDR_LOOPBACK_INIT,
};
if (bind(s, (struct sockaddr *)&addr6, sizeof(addr6)))
goto fail;
} else {
struct sockaddr_in addr4 = {
.sin_family = AF_INET,
.sin_port = htons(src),
.sin_addr = { .s_addr = htonl(INADDR_LOOPBACK) },
};
if (bind(s, (struct sockaddr *)&addr4, sizeof(addr4)))
goto fail;
}
sp->sock = s;
bitmap_set(udp_act[v6 ? V6 : V4][act], 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_new_ns_arg - Arguments for udp_splice_new_ns()
* @c: Execution context
* @v6: Set for IPv6
* @src: Source port of originating datagram, host order
* @dst: Destination port of originating datagram, host order
* @s: Newly created socket or negative error code
*/
struct udp_splice_new_ns_arg {
const struct ctx *c;
int v6;
in_port_t src;
int s;
};
/**
* udp_splice_new_ns() - Enter namespace and call udp_splice_new()
* @arg: See struct udp_splice_new_ns_arg
*
* Return: 0
*/
static int udp_splice_new_ns(void *arg)
{
struct udp_splice_new_ns_arg *a;
a = (struct udp_splice_new_ns_arg *)arg;
if (ns_enter(a->c))
return 0;
a->s = udp_splice_new(a->c, a->v6, a->src, true);
return 0;
}
/**
* udp_mmh_splice_port() - Is source address of message suitable for splicing?
* @v6: Is @sa a sockaddr_in6 (otherwise sockaddr_in)?
* @mmh: mmsghdr of incoming message
*
* Return: if @sa refers to localhost (127.0.0.1 or ::1) the port from
* @sa in host order, otherwise -1.
*/
static int udp_mmh_splice_port(bool v6, const struct mmsghdr *mmh)
{
const struct sockaddr_in6 *sa6 = mmh->msg_hdr.msg_name;
const struct sockaddr_in *sa4 = mmh->msg_hdr.msg_name;
if (v6 && IN6_IS_ADDR_LOOPBACK(&sa6->sin6_addr))
return ntohs(sa6->sin6_port);
if (!v6 && IN4_IS_ADDR_LOOPBACK(&sa4->sin_addr))
return ntohs(sa4->sin_port);
return -1;
}
/**
* udp_splice_sendfrom() - Send datagrams from given port to given port
* @c: Execution context
* @start: Index of first datagram in udp[46]_l2_buf
* @n: Number of datagrams to send
* @src: Datagrams will be sent from this port (on origin side)
* @dst: Datagrams will be send to this port (on destination side)
* @v6: Send as IPv6?
* @from_ns: If true send from pasta ns to init, otherwise reverse
* @allow_new: If true create sending socket if needed, if false discard
* if no sending socket is available
* @now: Timestamp
*/
static void udp_splice_sendfrom(const struct ctx *c, unsigned start, unsigned n,
in_port_t src, in_port_t dst,
bool v6, bool from_ns, bool allow_new,
const struct timespec *now)
{
struct mmsghdr *mmh_recv, *mmh_send;
unsigned int i;
int s;
if (v6) {
mmh_recv = udp6_l2_mh_sock;
mmh_send = udp6_mh_splice;
} else {
mmh_recv = udp4_l2_mh_sock;
mmh_send = udp4_mh_splice;
}
if (from_ns) {
src += c->udp.fwd_in.rdelta[src];
s = udp_splice_init[v6][src].sock;
if (!s && allow_new)
s = udp_splice_new(c, v6, src, false);
if (s < 0)
return;
udp_splice_ns[v6][dst].ts = now->tv_sec;
udp_splice_init[v6][src].ts = now->tv_sec;
} else {
src += c->udp.fwd_out.rdelta[src];
s = udp_splice_ns[v6][src].sock;
if (!s && allow_new) {
struct udp_splice_new_ns_arg arg = {
c, v6, src, -1,
};
NS_CALL(udp_splice_new_ns, &arg);
s = arg.s;
}
if (s < 0)
return;
udp_splice_init[v6][dst].ts = now->tv_sec;
udp_splice_ns[v6][src].ts = now->tv_sec;
}
for (i = start; i < start + n; i++)
mmh_send[i].msg_hdr.msg_iov->iov_len = mmh_recv[i].msg_len;
sendmmsg(s, mmh_send + start, n, MSG_NOSIGNAL);
}
/**
* udp_update_hdr4() - Update headers for one IPv4 datagram
* @c: Execution context
* @n: Index of buffer in udp4_l2_buf pool
* @dstport: Destination port number
* @now: Current timestamp
*
* Return: size of tap frame with headers
*/
static size_t udp_update_hdr4(const struct ctx *c, int n, in_port_t dstport,
const struct timespec *now)
{
struct udp4_l2_buf_t *b = &udp4_l2_buf[n];
in_port_t src_port;
size_t ip_len;
ip_len = udp4_l2_mh_sock[n].msg_len + sizeof(b->iph) + sizeof(b->uh);
b->iph.tot_len = htons(ip_len);
src_port = ntohs(b->s_in.sin_port);
if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_match) &&
IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.dns_host) &&
src_port == 53) {
b->iph.saddr = c->ip4.dns_match.s_addr;
} else if (IN4_IS_ADDR_LOOPBACK(&b->s_in.sin_addr) ||
IN4_IS_ADDR_UNSPECIFIED(&b->s_in.sin_addr)||
IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.addr_seen)) {
b->iph.saddr = c->ip4.gw.s_addr;
udp_tap_map[V4][src_port].ts = now->tv_sec;
udp_tap_map[V4][src_port].flags |= PORT_LOCAL;
if (IN4_ARE_ADDR_EQUAL(&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 {
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(dstport);
b->uh.len = htons(udp4_l2_mh_sock[n].msg_len + sizeof(b->uh));
return tap_iov_len(c, &b->taph, ip_len);
}
/**
* udp_update_hdr6() - Update headers for one IPv6 datagram
* @c: Execution context
* @n: Index of buffer in udp6_l2_buf pool
* @dstport: Destination port number
* @now: Current timestamp
*
* Return: size of tap frame with headers
*/
static size_t udp_update_hdr6(const struct ctx *c, int n, in_port_t dstport,
const struct timespec *now)
{
struct udp6_l2_buf_t *b = &udp6_l2_buf[n];
struct in6_addr *src;
in_port_t src_port;
size_t ip_len;
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_UNSPECIFIED(&c->ip6.dns_match) &&
IN6_ARE_ADDR_EQUAL(src, &c->ip6.dns_host) &&
src_port == 53) {
b->ip6h.daddr = c->ip6.addr_seen;
b->ip6h.saddr = c->ip6.dns_match;
} 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 {
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(dstport);
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;
return tap_iov_len(c, &b->taph, ip_len);
}
/**
* udp_tap_send() - Prepare UDP datagrams and send to tap interface
* @c: Execution context
* @start: Index of first datagram in udp[46]_l2_buf pool
* @n: Number of datagrams to send
* @dstport: Destination port number
* @v6: True if using IPv6
* @now: Current timestamp
*
* Return: size of tap frame with headers
*/
static void udp_tap_send(struct ctx *c,
unsigned int start, unsigned int n,
in_port_t dstport, bool v6, const struct timespec *now)
{
struct iovec *tap_iov;
unsigned int i;
if (v6)
tap_iov = udp6_l2_iov_tap;
else
tap_iov = udp4_l2_iov_tap;
for (i = start; i < start + n; i++) {
size_t buf_len;
if (v6)
buf_len = udp_update_hdr6(c, i, dstport, now);
else
buf_len = udp_update_hdr4(c, i, dstport, now);
tap_iov[i].iov_len = buf_len;
}
tap_send_frames(c, tap_iov + start, n);
}
/**
* udp_sock_handler() - Handle new data from socket
* @c: Execution context
* @ref: epoll reference
* @events: epoll events bitmap
* @now: Current timestamp
*
* #syscalls recvmmsg
*/
void udp_sock_handler(struct ctx *c, union epoll_ref ref, uint32_t events,
const struct timespec *now)
{
/* For not entirely clear reasons (data locality?) pasta gets
* better throughput if we receive tap datagrams one at a
* atime. For small splice datagrams throughput is slightly
* better if we do batch, but it's slightly worse for large
* splice datagrams. Since we don't know before we receive
* whether we'll use tap or splice, always go one at a time
* for pasta mode.
*/
ssize_t n = (c->mode == MODE_PASST ? UDP_MAX_FRAMES : 1);
in_port_t dstport = ref.r.p.udp.udp.port;
bool v6 = ref.r.p.udp.udp.v6;
struct mmsghdr *mmh_recv;
int i, m;
if (!(events & EPOLLIN))
return;
if (v6) {
mmh_recv = udp6_l2_mh_sock;
udp6_localname.sin6_port = htons(dstport);
} else {
mmh_recv = udp4_l2_mh_sock;
udp4_localname.sin_port = htons(dstport);
}
n = recvmmsg(ref.r.s, mmh_recv, n, 0, NULL);
if (n <= 0)
return;
for (i = 0; i < n; i += m) {
int splicefrom = -1;
m = n;
if (ref.r.p.udp.udp.splice) {
splicefrom = udp_mmh_splice_port(v6, mmh_recv + i);
for (m = 1; i + m < n; m++) {
int p;
p = udp_mmh_splice_port(v6, mmh_recv + i + m);
if (p != splicefrom)
break;
}
}
if (splicefrom >= 0)
udp_splice_sendfrom(c, i, m, splicefrom, dstport,
v6, ref.r.p.udp.udp.ns,
ref.r.p.udp.udp.orig, now);
else
udp_tap_send(c, i, m, dstport, v6, now);
}
}
/**
* 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 (IN4_ARE_ADDR_EQUAL(&s_in.sin_addr, &c->ip4.dns_match) &&
ntohs(s_in.sin_port) == 53) {
s_in.sin_addr = c->ip4.dns_host;
} else if (IN4_ARE_ADDR_EQUAL(&s_in.sin_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 = c->ip4.addr_seen;
}
if (!(s = udp_tap_map[V4][src].sock)) {
union udp_epoll_ref uref = { .udp.port = src };
in_addr_t bind_addr = { 0 };
const char *bind_if = NULL;
if (!IN6_IS_ADDR_LOOPBACK(&s_in.sin_addr) &&
*c->ip6.ifname_out)
bind_if = c->ip6.ifname_out;
if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.addr_out) &&
!IN4_IS_ADDR_LOOPBACK(&s_in.sin_addr))
bind_addr = c->ip4.addr_out.s_addr;
s = sock_l4(c, AF_INET, IPPROTO_UDP, &bind_addr,
bind_if, 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;
} else {
s_in6 = (struct sockaddr_in6) {
.sin6_family = AF_INET6,
.sin6_port = uh->dest,
.sin6_addr = *(struct in6_addr *)addr,
};
const struct in6_addr *bind_addr = &in6addr_any;
sa = (struct sockaddr *)&s_in6;
sl = sizeof(s_in6);
if (IN6_ARE_ADDR_EQUAL(addr, &c->ip6.dns_match) &&
ntohs(s_in6.sin6_port) == 53) {
s_in6.sin6_addr = c->ip6.dns_host;
} else 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_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.v6 = 1,
.udp.port = src };
const char *bind_if = NULL;
if (!IN6_IS_ADDR_LOOPBACK(&s_in6.sin6_addr) &&
*c->ip6.ifname_out)
bind_if = c->ip6.ifname_out;
if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.addr_out) &&
!IN6_IS_ADDR_LOOPBACK(&s_in6.sin6_addr) &&
!IN6_IS_ADDR_LINKLOCAL(&s_in6.sin6_addr))
bind_addr = &c->ip6.addr_out;
s = sock_l4(c, AF_INET6, IPPROTO_UDP, bind_addr,
bind_if, 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
* @ifname: Name of interface to bind to, NULL if not configured
* @port: Port, host order
*
* Return: 0 on (partial) success, negative error code on (complete) failure
*/
int udp_sock_init(const struct ctx *c, int ns, sa_family_t af,
const void *addr, const char *ifname, in_port_t port)
{
union udp_epoll_ref uref = { .u32 = 0 };
int s, r4 = SOCKET_MAX + 1, r6 = SOCKET_MAX + 1;
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) && c->ifi4) {
uref.udp.v6 = 0;
uref.udp.splice = (c->mode == MODE_PASTA);
uref.udp.orig = true;
if (!ns) {
r4 = s = sock_l4(c, AF_INET, IPPROTO_UDP, addr,
ifname, port, uref.u32);
udp_tap_map[V4][uref.udp.port].sock = s < 0 ? -1 : s;
udp_splice_init[V4][port].sock = s < 0 ? -1 : s;
} else {
struct in_addr loopback = { htonl(INADDR_LOOPBACK) };
uref.udp.ns = true;
r4 = s = sock_l4(c, AF_INET, IPPROTO_UDP, &loopback,
ifname, port, uref.u32);
udp_splice_ns[V4][port].sock = s < 0 ? -1 : s;
}
}
if ((af == AF_INET6 || af == AF_UNSPEC) && c->ifi6) {
uref.udp.v6 = 1;
uref.udp.splice = (c->mode == MODE_PASTA);
uref.udp.orig = true;
if (!ns) {
r6 = s = sock_l4(c, AF_INET6, IPPROTO_UDP, addr,
ifname, port, uref.u32);
udp_tap_map[V6][uref.udp.port].sock = s < 0 ? -1 : s;
udp_splice_init[V6][port].sock = s < 0 ? -1 : s;
} else {
uref.udp.ns = true;
r6 = s = sock_l4(c, AF_INET6, IPPROTO_UDP,
&in6addr_loopback,
ifname, port, uref.u32);
udp_splice_ns[V6][port].sock = s < 0 ? -1 : s;
}
}
if (IN_INTERVAL(0, SOCKET_MAX, r4) || IN_INTERVAL(0, SOCKET_MAX, r6))
return 0;
return r4 < 0 ? r4 : r6;
}
/**
* udp_sock_init_init() - Bind sockets in init namespace for inbound connections
* @c: Execution context
*/
static void udp_sock_init_init(struct ctx *c)
{
unsigned dst;
for (dst = 0; dst < NUM_PORTS; dst++) {
if (!bitmap_isset(c->udp.fwd_in.f.map, dst))
continue;
udp_sock_init(c, 0, AF_UNSPEC, NULL, NULL, dst);
}
}
/**
* udp_sock_init_ns() - Bind sockets in namespace for outbound 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 < NUM_PORTS; dst++) {
if (!bitmap_isset(c->udp.fwd_out.f.map, dst))
continue;
udp_sock_init(c, 1, AF_UNSPEC, NULL, NULL, dst);
}
return 0;
}
/**
* udp_splice_iov_init() - Set up buffers and descriptors for recvmmsg/sendmmsg
*/
static void udp_splice_iov_init(void)
{
int i;
for (i = 0; i < UDP_MAX_FRAMES; i++) {
struct msghdr *mh4 = &udp4_mh_splice[i].msg_hdr;
struct msghdr *mh6 = &udp6_mh_splice[i].msg_hdr;
mh4->msg_name = &udp4_localname;
mh4->msg_namelen = sizeof(udp4_localname);
mh6->msg_name = &udp6_localname;
mh6->msg_namelen = sizeof(udp6_localname);
udp4_iov_splice[i].iov_base = udp4_l2_buf[i].data;
udp6_iov_splice[i].iov_base = udp6_l2_buf[i].data;
mh4->msg_iov = &udp4_iov_splice[i];
mh6->msg_iov = &udp6_iov_splice[i];
mh4->msg_iovlen = mh6->msg_iovlen = 1;
}
}
/**
* 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(c);
if (c->ifi6)
udp_sock6_iov_init(c);
udp_invert_portmap(&c->udp.fwd_in);
udp_invert_portmap(&c->udp.fwd_out);
if (c->mode == MODE_PASTA) {
udp_splice_iov_init();
udp_sock_init_init(c);
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_SPLICE_INIT:
sp = &udp_splice_init[v6 ? V6 : V4][port];
if (ts->tv_sec - sp->ts > UDP_CONN_TIMEOUT)
s = sp->sock;
break;
case UDP_ACT_SPLICE_NS:
sp = &udp_splice_ns[v6 ? V6 : V4][port];
if (ts->tv_sec - sp->ts > UDP_CONN_TIMEOUT)
s = sp->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;
}
}
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