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passt/udp.c
David Gibson 2fa91ee391 udp: Handle errors on UDP sockets 
Currently we ignore all events other than EPOLLIN on UDP sockets.  This
means that if we ever receive an EPOLLERR event, we'll enter an infinite
loop on epoll, because we'll never do anything to clear the error.

Luckily that doesn't seem to have happened in practice, but it's certainly
fragile.  Furthermore changes in how we handle UDP sockets with the flow
table mean we will start receiving error events.

Add handling of EPOLLERR events.  For now we just read the error from the
error queue (thereby clearing the error state) and print a debug message.
We can add more substantial handling of specific events in future if we
want to.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
2024-07-17 07:05:21 +02:00

1341 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 <assert.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 <linux/errqueue.h>
#include "checksum.h"
#include "util.h"
#include "iov.h"
#include "ip.h"
#include "siphash.h"
#include "inany.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 recent activity type seen from/to port
* @ts: Activity timestamp from tap, used for socket aging
*/
struct udp_tap_port {
int sock;
uint8_t flags;
#define PORT_LOCAL BIT(0) /* Port was contacted from local address */
#define PORT_LOOPBACK BIT(1) /* Port was contacted from loopback address */
#define PORT_GUA BIT(2) /* Port was contacted from global unicast */
#define PORT_DNS_FWD BIT(3) /* Port used as source for DNS remapped query */
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 */
/**
* struct udp_payload_t - UDP header and data for inbound messages
* @uh: UDP header
* @data: UDP data
*/
static struct udp_payload_t {
struct udphdr uh;
char data[USHRT_MAX - sizeof(struct udphdr)];
#ifdef __AVX2__
} __attribute__ ((packed, aligned(32)))
#else
} __attribute__ ((packed, aligned(__alignof__(unsigned int))))
#endif
udp_payload[UDP_MAX_FRAMES];
/* Ethernet header for IPv4 frames */
static struct ethhdr udp4_eth_hdr;
/* Ethernet header for IPv6 frames */
static struct ethhdr udp6_eth_hdr;
/**
* struct udp_meta_t - Pre-cooked headers and metadata for UDP packets
* @ip6h: Pre-filled IPv6 header (except for payload_len and addresses)
* @ip4h: Pre-filled IPv4 header (except for tot_len and saddr)
* @taph: Tap backend specific header
* @s_in: Source socket address, filled in by recvmmsg()
* @splicesrc: Source port for splicing, or -1 if not spliceable
*/
static struct udp_meta_t {
struct ipv6hdr ip6h;
struct iphdr ip4h;
struct tap_hdr taph;
union sockaddr_inany s_in;
int splicesrc;
}
#ifdef __AVX2__
__attribute__ ((aligned(32)))
#endif
udp_meta[UDP_MAX_FRAMES];
/**
* enum udp_iov_idx - Indices for the buffers making up a single UDP frame
* @UDP_IOV_TAP tap specific header
* @UDP_IOV_ETH Ethernet header
* @UDP_IOV_IP IP (v4/v6) header
* @UDP_IOV_PAYLOAD IP payload (UDP header + data)
* @UDP_NUM_IOVS the number of entries in the iovec array
*/
enum udp_iov_idx {
UDP_IOV_TAP = 0,
UDP_IOV_ETH = 1,
UDP_IOV_IP = 2,
UDP_IOV_PAYLOAD = 3,
UDP_NUM_IOVS
};
/* IOVs and msghdr arrays for receiving datagrams from sockets */
static struct iovec udp_iov_recv [UDP_MAX_FRAMES];
static struct mmsghdr udp4_mh_recv [UDP_MAX_FRAMES];
static struct mmsghdr udp6_mh_recv [UDP_MAX_FRAMES];
/* IOVs and msghdr arrays for sending "spliced" datagrams to sockets */
static union sockaddr_inany udp_splice_to;
static struct iovec udp_iov_splice [UDP_MAX_FRAMES];
static struct mmsghdr udp_mh_splice [UDP_MAX_FRAMES];
/* IOVs for L2 frames */
static struct iovec udp_l2_iov [UDP_MAX_FRAMES][UDP_NUM_IOVS];
/**
* udp_portmap_clear() - Clear UDP port map before configuration
*/
void udp_portmap_clear(void)
{
unsigned i;
for (i = 0; i < NUM_PORTS; i++) {
udp_tap_map[V4][i].sock = udp_tap_map[V6][i].sock = -1;
udp_splice_ns[V4][i].sock = udp_splice_ns[V6][i].sock = -1;
udp_splice_init[V4][i].sock = udp_splice_init[V6][i].sock = -1;
}
}
/**
* 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_fwd_ports *fwd)
{
unsigned int i;
static_assert(ARRAY_SIZE(fwd->f.delta) == ARRAY_SIZE(fwd->rdelta),
"Forward and reverse delta arrays must have same size");
for (i = 0; i < ARRAY_SIZE(fwd->f.delta); i++) {
in_port_t delta = fwd->f.delta[i];
if (delta) {
/* Keep rport calculation separate from its usage: we
* need to perform the sum in in_port_t width (that is,
* modulo 65536), but C promotion rules would sum the
* two terms as 'int', if we just open-coded the array
* index as 'i + delta'.
*/
in_port_t rport = i + delta;
fwd->rdelta[rport] = NUM_PORTS - delta;
}
}
}
/**
* 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
*/
void udp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s)
{
eth_update_mac(&udp4_eth_hdr, eth_d, eth_s);
eth_update_mac(&udp6_eth_hdr, eth_d, eth_s);
}
/**
* udp_iov_init_one() - Initialise scatter-gather lists for one buffer
* @c: Execution context
* @i: Index of buffer to initialize
*/
static void udp_iov_init_one(const struct ctx *c, size_t i)
{
struct udp_payload_t *payload = &udp_payload[i];
struct udp_meta_t *meta = &udp_meta[i];
struct iovec *siov = &udp_iov_recv[i];
struct iovec *tiov = udp_l2_iov[i];
*meta = (struct udp_meta_t) {
.ip4h = L2_BUF_IP4_INIT(IPPROTO_UDP),
.ip6h = L2_BUF_IP6_INIT(IPPROTO_UDP),
};
*siov = IOV_OF_LVALUE(payload->data);
tiov[UDP_IOV_TAP] = tap_hdr_iov(c, &meta->taph);
tiov[UDP_IOV_PAYLOAD].iov_base = payload;
/* It's useful to have separate msghdr arrays for receiving. Otherwise,
* an IPv4 recv() will alter msg_namelen, so we'd have to reset it every
* time or risk truncating the address on future IPv6 recv()s.
*/
if (c->ifi4) {
struct msghdr *mh = &udp4_mh_recv[i].msg_hdr;
mh->msg_name = &meta->s_in;
mh->msg_namelen = sizeof(struct sockaddr_in);
mh->msg_iov = siov;
mh->msg_iovlen = 1;
}
if (c->ifi6) {
struct msghdr *mh = &udp6_mh_recv[i].msg_hdr;
mh->msg_name = &meta->s_in;
mh->msg_namelen = sizeof(struct sockaddr_in6);
mh->msg_iov = siov;
mh->msg_iovlen = 1;
}
}
/**
* udp_iov_init() - Initialise scatter-gather L2 buffers
* @c: Execution context
*/
static void udp_iov_init(const struct ctx *c)
{
size_t i;
udp4_eth_hdr.h_proto = htons_constant(ETH_P_IP);
udp6_eth_hdr.h_proto = htons_constant(ETH_P_IPV6);
for (i = 0; i < UDP_MAX_FRAMES; i++)
udp_iov_init_one(c, i);
}
/**
* 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
* @ns: Does the splice originate in the ns or not
*
* 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 = { .type = EPOLL_TYPE_UDP,
.udp = { .splice = true, .v6 = v6, .port = src }
};
struct udp_splice_port *sp;
int act, s;
if (ns) {
ref.udp.pif = PIF_SPLICE;
sp = &udp_splice_ns[v6 ? V6 : V4][src];
act = UDP_ACT_SPLICE_NS;
} else {
ref.udp.pif = PIF_HOST;
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 > FD_REF_MAX) {
close(s);
return -EIO;
}
if (s < 0)
return s;
ref.fd = 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 = IN4ADDR_LOOPBACK_INIT,
};
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;
ns_enter(a->c);
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?
* @ref: epoll reference for incoming message's origin socket
* @mmh: mmsghdr of incoming message
*
* Return: if source address of message in @mmh refers to localhost (127.0.0.1
* or ::1) its source port (host order), otherwise -1.
*/
static int udp_mmh_splice_port(union epoll_ref ref, const struct mmsghdr *mmh)
{
const struct sockaddr_in6 *sa6 = mmh->msg_hdr.msg_name;
const struct sockaddr_in *sa4 = mmh->msg_hdr.msg_name;
ASSERT(ref.type == EPOLL_TYPE_UDP);
if (!ref.udp.splice)
return -1;
if (ref.udp.v6 && IN6_IS_ADDR_LOOPBACK(&sa6->sin6_addr))
return ntohs(sa6->sin6_port);
if (!ref.udp.v6 && IN4_IS_ADDR_LOOPBACK(&sa4->sin_addr))
return ntohs(sa4->sin_port);
return -1;
}
/**
* udp_splice_prepare() - Prepare one datagram for splicing
* @mmh: Receiving mmsghdr array
* @idx: Index of the datagram to prepare
*/
static void udp_splice_prepare(struct mmsghdr *mmh, unsigned idx)
{
udp_mh_splice[idx].msg_hdr.msg_iov->iov_len = mmh[idx].msg_len;
}
/**
* udp_splice_send() - Send a batch of datagrams from socket to socket
* @c: Execution context
* @start: Index of batch's first datagram in udp[46]_l2_buf
* @n: Number of datagrams in batch
* @src: Source port for datagram (target side)
* @dst: Destination port for datagrams (target side)
* @ref: epoll reference for origin socket
* @now: Timestamp
*/
static void udp_splice_send(const struct ctx *c, size_t start, size_t n,
in_port_t src, in_port_t dst,
union epoll_ref ref,
const struct timespec *now)
{
int s;
if (ref.udp.v6) {
udp_splice_to.sa6 = (struct sockaddr_in6) {
.sin6_family = AF_INET6,
.sin6_addr = in6addr_loopback,
.sin6_port = htons(dst),
};
} else {
udp_splice_to.sa4 = (struct sockaddr_in) {
.sin_family = AF_INET,
.sin_addr = in4addr_loopback,
.sin_port = htons(dst),
};
}
if (ref.udp.pif == PIF_SPLICE) {
src += c->udp.fwd_in.rdelta[src];
s = udp_splice_init[ref.udp.v6][src].sock;
if (s < 0 && ref.udp.orig)
s = udp_splice_new(c, ref.udp.v6, src, false);
if (s < 0)
return;
udp_splice_ns[ref.udp.v6][dst].ts = now->tv_sec;
udp_splice_init[ref.udp.v6][src].ts = now->tv_sec;
} else {
ASSERT(ref.udp.pif == PIF_HOST);
src += c->udp.fwd_out.rdelta[src];
s = udp_splice_ns[ref.udp.v6][src].sock;
if (s < 0 && ref.udp.orig) {
struct udp_splice_new_ns_arg arg = {
c, ref.udp.v6, src, -1,
};
NS_CALL(udp_splice_new_ns, &arg);
s = arg.s;
}
if (s < 0)
return;
udp_splice_init[ref.udp.v6][dst].ts = now->tv_sec;
udp_splice_ns[ref.udp.v6][src].ts = now->tv_sec;
}
sendmmsg(s, udp_mh_splice + start, n, MSG_NOSIGNAL);
}
/**
* udp_update_hdr4() - Update headers for one IPv4 datagram
* @c: Execution context
* @ip4h: Pre-filled IPv4 header (except for tot_len and saddr)
* @s_in: Source socket address, filled in by recvmmsg()
* @bp: Pointer to udp_payload_t to update
* @dstport: Destination port number
* @dlen: Length of UDP payload
* @now: Current timestamp
*
* Return: size of IPv4 payload (UDP header + data)
*/
static size_t udp_update_hdr4(const struct ctx *c,
struct iphdr *ip4h, const struct sockaddr_in *s_in,
struct udp_payload_t *bp,
in_port_t dstport, size_t dlen,
const struct timespec *now)
{
const struct in_addr dst = c->ip4.addr_seen;
in_port_t srcport = ntohs(s_in->sin_port);
size_t l4len = dlen + sizeof(bp->uh);
size_t l3len = l4len + sizeof(*ip4h);
struct in_addr src = s_in->sin_addr;
if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_match) &&
IN4_ARE_ADDR_EQUAL(&src, &c->ip4.dns_host) && srcport == 53 &&
(udp_tap_map[V4][dstport].flags & PORT_DNS_FWD)) {
src = c->ip4.dns_match;
} else if (IN4_IS_ADDR_LOOPBACK(&src) ||
IN4_ARE_ADDR_EQUAL(&src, &c->ip4.addr_seen)) {
udp_tap_map[V4][srcport].ts = now->tv_sec;
udp_tap_map[V4][srcport].flags |= PORT_LOCAL;
if (IN4_IS_ADDR_LOOPBACK(&src))
udp_tap_map[V4][srcport].flags |= PORT_LOOPBACK;
else
udp_tap_map[V4][srcport].flags &= ~PORT_LOOPBACK;
bitmap_set(udp_act[V4][UDP_ACT_TAP], srcport);
src = c->ip4.gw;
}
ip4h->tot_len = htons(l3len);
ip4h->daddr = dst.s_addr;
ip4h->saddr = src.s_addr;
ip4h->check = csum_ip4_header(l3len, IPPROTO_UDP, src, dst);
bp->uh.source = s_in->sin_port;
bp->uh.dest = htons(dstport);
bp->uh.len = htons(l4len);
csum_udp4(&bp->uh, src, dst, bp->data, dlen);
return l4len;
}
/**
* udp_update_hdr6() - Update headers for one IPv6 datagram
* @c: Execution context
* @ip6h: Pre-filled IPv6 header (except for payload_len and addresses)
* @s_in: Source socket address, filled in by recvmmsg()
* @bp: Pointer to udp_payload_t to update
* @dstport: Destination port number
* @dlen: Length of UDP payload
* @now: Current timestamp
*
* Return: size of IPv6 payload (UDP header + data)
*/
static size_t udp_update_hdr6(const struct ctx *c,
struct ipv6hdr *ip6h, struct sockaddr_in6 *s_in6,
struct udp_payload_t *bp,
in_port_t dstport, size_t dlen,
const struct timespec *now)
{
const struct in6_addr *src = &s_in6->sin6_addr;
const struct in6_addr *dst = &c->ip6.addr_seen;
in_port_t srcport = ntohs(s_in6->sin6_port);
uint16_t l4len = dlen + sizeof(bp->uh);
if (IN6_IS_ADDR_LINKLOCAL(src)) {
dst = &c->ip6.addr_ll_seen;
} else if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_match) &&
IN6_ARE_ADDR_EQUAL(src, &c->ip6.dns_host) &&
srcport == 53 &&
(udp_tap_map[V4][dstport].flags & PORT_DNS_FWD)) {
src = &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)) {
udp_tap_map[V6][srcport].ts = now->tv_sec;
udp_tap_map[V6][srcport].flags |= PORT_LOCAL;
if (IN6_IS_ADDR_LOOPBACK(src))
udp_tap_map[V6][srcport].flags |= PORT_LOOPBACK;
else
udp_tap_map[V6][srcport].flags &= ~PORT_LOOPBACK;
if (IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr))
udp_tap_map[V6][srcport].flags |= PORT_GUA;
else
udp_tap_map[V6][srcport].flags &= ~PORT_GUA;
bitmap_set(udp_act[V6][UDP_ACT_TAP], srcport);
dst = &c->ip6.addr_ll_seen;
if (IN6_IS_ADDR_LINKLOCAL(&c->ip6.gw))
src = &c->ip6.gw;
else
src = &c->ip6.addr_ll;
}
ip6h->payload_len = htons(l4len);
ip6h->daddr = *dst;
ip6h->saddr = *src;
ip6h->version = 6;
ip6h->nexthdr = IPPROTO_UDP;
ip6h->hop_limit = 255;
bp->uh.source = s_in6->sin6_port;
bp->uh.dest = htons(dstport);
bp->uh.len = ip6h->payload_len;
csum_udp6(&bp->uh, src, dst, bp->data, dlen);
return l4len;
}
/**
* udp_tap_prepare() - Convert one datagram into a tap frame
* @c: Execution context
* @mmh: Receiving mmsghdr array
* @idx: Index of the datagram to prepare
* @dstport: Destination port
* @v6: Prepare for IPv6?
* @now: Current timestamp
*/
static void udp_tap_prepare(const struct ctx *c, const struct mmsghdr *mmh,
unsigned idx, in_port_t dstport, bool v6,
const struct timespec *now)
{
struct iovec (*tap_iov)[UDP_NUM_IOVS] = &udp_l2_iov[idx];
struct udp_payload_t *bp = &udp_payload[idx];
struct udp_meta_t *bm = &udp_meta[idx];
size_t l4len;
if (v6) {
l4len = udp_update_hdr6(c, &bm->ip6h, &bm->s_in.sa6, bp,
dstport, mmh[idx].msg_len, now);
tap_hdr_update(&bm->taph, l4len + sizeof(bm->ip6h) +
sizeof(udp6_eth_hdr));
(*tap_iov)[UDP_IOV_ETH] = IOV_OF_LVALUE(udp6_eth_hdr);
(*tap_iov)[UDP_IOV_IP] = IOV_OF_LVALUE(bm->ip6h);
} else {
l4len = udp_update_hdr4(c, &bm->ip4h, &bm->s_in.sa4, bp,
dstport, mmh[idx].msg_len, now);
tap_hdr_update(&bm->taph, l4len + sizeof(bm->ip4h) +
sizeof(udp4_eth_hdr));
(*tap_iov)[UDP_IOV_ETH] = IOV_OF_LVALUE(udp4_eth_hdr);
(*tap_iov)[UDP_IOV_IP] = IOV_OF_LVALUE(bm->ip4h);
}
(*tap_iov)[UDP_IOV_PAYLOAD].iov_len = l4len;
}
/**
* udp_sock_recverr() - Receive and clear an error from a socket
* @s: Socket to receive from
*
* Return: true if errors received and processed, false if no more errors
*
* #syscalls recvmsg
*/
static bool udp_sock_recverr(int s)
{
const struct sock_extended_err *ee;
const struct cmsghdr *hdr;
char buf[CMSG_SPACE(sizeof(*ee))];
struct msghdr mh = {
.msg_name = NULL,
.msg_namelen = 0,
.msg_iov = NULL,
.msg_iovlen = 0,
.msg_control = buf,
.msg_controllen = sizeof(buf),
};
ssize_t rc;
rc = recvmsg(s, &mh, MSG_ERRQUEUE);
if (rc < 0) {
if (errno != EAGAIN && errno != EWOULDBLOCK)
err_perror("Failed to read error queue");
return false;
}
if (!(mh.msg_flags & MSG_ERRQUEUE)) {
err("Missing MSG_ERRQUEUE flag reading error queue");
return false;
}
hdr = CMSG_FIRSTHDR(&mh);
if (!((hdr->cmsg_level == IPPROTO_IP &&
hdr->cmsg_type == IP_RECVERR) ||
(hdr->cmsg_level == IPPROTO_IPV6 &&
hdr->cmsg_type == IPV6_RECVERR))) {
err("Unexpected cmsg reading error queue");
return false;
}
ee = (const struct sock_extended_err *)CMSG_DATA(hdr);
/* TODO: When possible propagate and otherwise handle errors */
debug("%s error on UDP socket %i: %s",
str_ee_origin(ee), s, strerror(ee->ee_errno));
return true;
}
/**
* udp_sock_recv() - Receive datagrams from a socket
* @c: Execution context
* @s: Socket to receive from
* @events: epoll events bitmap
* @mmh mmsghdr array to receive into
*
* #syscalls recvmmsg
*/
static int udp_sock_recv(const struct ctx *c, int s, uint32_t events,
struct mmsghdr *mmh)
{
/* 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.
*/
int n = (c->mode == MODE_PASTA ? 1 : UDP_MAX_FRAMES);
ASSERT(!c->no_udp);
/* Clear any errors first */
if (events & EPOLLERR) {
while (udp_sock_recverr(s))
;
}
if (!(events & EPOLLIN))
return 0;
n = recvmmsg(s, mmh, n, 0, NULL);
if (n < 0) {
err_perror("Error receiving datagrams");
return 0;
}
return n;
}
/**
* udp_buf_sock_handler() - Handle new data from socket
* @c: Execution context
* @ref: epoll reference
* @events: epoll events bitmap
* @now: Current timestamp
*
* #syscalls recvmmsg
*/
void udp_buf_sock_handler(const struct ctx *c, union epoll_ref ref, uint32_t events,
const struct timespec *now)
{
struct mmsghdr *mmh_recv = ref.udp.v6 ? udp6_mh_recv : udp4_mh_recv;
in_port_t dstport = ref.udp.port;
int n, i;
if ((n = udp_sock_recv(c, ref.fd, events, mmh_recv)) <= 0)
return;
if (ref.udp.pif == PIF_SPLICE)
dstport += c->udp.fwd_out.f.delta[dstport];
else if (ref.udp.pif == PIF_HOST)
dstport += c->udp.fwd_in.f.delta[dstport];
/* We divide datagrams into batches based on how we need to send them,
* determined by udp_meta[i].splicesrc. To avoid either two passes
* through the array, or recalculating splicesrc for a single entry, we
* have to populate it one entry *ahead* of the loop counter.
*/
udp_meta[0].splicesrc = udp_mmh_splice_port(ref, mmh_recv);
for (i = 0; i < n; ) {
int batchsrc = udp_meta[i].splicesrc;
int batchstart = i;
do {
if (batchsrc >= 0) {
udp_splice_prepare(mmh_recv, i);
} else {
udp_tap_prepare(c, mmh_recv, i, dstport,
ref.udp.v6, now);
}
if (++i >= n)
break;
udp_meta[i].splicesrc = udp_mmh_splice_port(ref,
&mmh_recv[i]);
} while (udp_meta[i].splicesrc == batchsrc);
if (batchsrc >= 0) {
udp_splice_send(c, batchstart, i - batchstart,
batchsrc, dstport, ref, now);
} else {
tap_send_frames(c, &udp_l2_iov[batchstart][0],
UDP_NUM_IOVS, i - batchstart);
}
}
}
/**
* udp_tap_handler() - Handle packets from tap
* @c: Execution context
* @pif: pif on which the packet is arriving
* @af: Address family, AF_INET or AF_INET6
* @saddr: Source address
* @daddr: Destination address
* @p: Pool of UDP packets, with UDP headers
* @idx: Index of first packet to process
* @now: Current timestamp
*
* Return: count of consumed packets
*
* #syscalls sendmmsg
*/
int udp_tap_handler(struct ctx *c, uint8_t pif,
sa_family_t af, const void *saddr, const void *daddr,
const struct pool *p, int idx, const struct timespec *now)
{
struct mmsghdr mm[UIO_MAXIOV];
struct iovec m[UIO_MAXIOV];
struct sockaddr_in6 s_in6;
struct sockaddr_in s_in;
const struct udphdr *uh;
struct sockaddr *sa;
int i, s, count = 0;
in_port_t src, dst;
socklen_t sl;
(void)saddr;
(void)pif;
ASSERT(!c->no_udp);
uh = packet_get(p, idx, 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);
src += c->udp.fwd_in.rdelta[src];
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 *)daddr,
};
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;
udp_tap_map[V4][src].ts = now->tv_sec;
udp_tap_map[V4][src].flags |= PORT_DNS_FWD;
bitmap_set(udp_act[V4][UDP_ACT_TAP], src);
} 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;
}
debug("UDP from tap src=%hu dst=%hu, s=%d",
src, dst, udp_tap_map[V4][src].sock);
if ((s = udp_tap_map[V4][src].sock) < 0) {
struct in_addr bind_addr = IN4ADDR_ANY_INIT;
union udp_epoll_ref uref = {
.port = src,
.pif = PIF_HOST,
};
const char *bind_if = NULL;
if (!IN4_IS_ADDR_LOOPBACK(&s_in.sin_addr))
bind_if = c->ip4.ifname_out;
if (!IN4_IS_ADDR_LOOPBACK(&s_in.sin_addr))
bind_addr = c->ip4.addr_out;
s = sock_l4(c, AF_INET, EPOLL_TYPE_UDP, &bind_addr,
bind_if, src, uref.u32);
if (s < 0)
return p->count - idx;
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 *)daddr,
};
const struct in6_addr *bind_addr = &in6addr_any;
sa = (struct sockaddr *)&s_in6;
sl = sizeof(s_in6);
if (IN6_ARE_ADDR_EQUAL(daddr, &c->ip6.dns_match) &&
ntohs(s_in6.sin6_port) == 53) {
s_in6.sin6_addr = c->ip6.dns_host;
udp_tap_map[V6][src].ts = now->tv_sec;
udp_tap_map[V6][src].flags |= PORT_DNS_FWD;
bitmap_set(udp_act[V6][UDP_ACT_TAP], src);
} else if (IN6_ARE_ADDR_EQUAL(daddr, &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) < 0) {
union udp_epoll_ref uref = {
.v6 = 1,
.port = src,
.pif = PIF_HOST,
};
const char *bind_if = NULL;
if (!IN6_IS_ADDR_LOOPBACK(&s_in6.sin6_addr))
bind_if = c->ip6.ifname_out;
if (!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, EPOLL_TYPE_UDP, bind_addr,
bind_if, src, uref.u32);
if (s < 0)
return p->count - idx;
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 - idx; i++) {
struct udphdr *uh_send;
size_t len;
uh_send = packet_get(p, idx + i, 0, sizeof(*uh), &len);
if (!uh_send)
return p->count - idx;
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 = { .splice = (c->mode == MODE_PASTA),
.orig = true, .port = port };
int s, r4 = FD_REF_MAX + 1, r6 = FD_REF_MAX + 1;
ASSERT(!c->no_udp);
if (ns)
uref.pif = PIF_SPLICE;
else
uref.pif = PIF_HOST;
if ((af == AF_INET || af == AF_UNSPEC) && c->ifi4) {
uref.v6 = 0;
if (!ns) {
r4 = s = sock_l4(c, AF_INET, EPOLL_TYPE_UDP, addr,
ifname, port, uref.u32);
udp_tap_map[V4][port].sock = s < 0 ? -1 : s;
udp_splice_init[V4][port].sock = s < 0 ? -1 : s;
} else {
r4 = s = sock_l4(c, AF_INET, EPOLL_TYPE_UDP,
&in4addr_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.v6 = 1;
if (!ns) {
r6 = s = sock_l4(c, AF_INET6, EPOLL_TYPE_UDP, addr,
ifname, port, uref.u32);
udp_tap_map[V6][port].sock = s < 0 ? -1 : s;
udp_splice_init[V6][port].sock = s < 0 ? -1 : s;
} else {
r6 = s = sock_l4(c, AF_INET6, EPOLL_TYPE_UDP,
&in6addr_loopback,
ifname, port, uref.u32);
udp_splice_ns[V6][port].sock = s < 0 ? -1 : s;
}
}
if (IN_INTERVAL(0, FD_REF_MAX, r4) || IN_INTERVAL(0, FD_REF_MAX, r6))
return 0;
return r4 < 0 ? r4 : r6;
}
/**
* 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 *mh = &udp_mh_splice[i].msg_hdr;
mh->msg_name = &udp_splice_to;
mh->msg_namelen = sizeof(udp_splice_to);
udp_iov_splice[i].iov_base = udp_payload[i].data;
mh->msg_iov = &udp_iov_splice[i];
mh->msg_iovlen = 1;
}
}
/**
* 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
* @now: Current timestamp
*/
static void udp_timer_one(struct ctx *c, int v6, enum udp_act_type type,
in_port_t port, const struct timespec *now)
{
struct udp_splice_port *sp;
struct udp_tap_port *tp;
int *sockp = NULL;
switch (type) {
case UDP_ACT_TAP:
tp = &udp_tap_map[v6 ? V6 : V4][port];
if (now->tv_sec - tp->ts > UDP_CONN_TIMEOUT) {
sockp = &tp->sock;
tp->flags = 0;
}
break;
case UDP_ACT_SPLICE_INIT:
sp = &udp_splice_init[v6 ? V6 : V4][port];
if (now->tv_sec - sp->ts > UDP_CONN_TIMEOUT)
sockp = &sp->sock;
break;
case UDP_ACT_SPLICE_NS:
sp = &udp_splice_ns[v6 ? V6 : V4][port];
if (now->tv_sec - sp->ts > UDP_CONN_TIMEOUT)
sockp = &sp->sock;
break;
default:
return;
}
if (sockp && *sockp >= 0) {
int s = *sockp;
*sockp = -1;
epoll_ctl(c->epollfd, EPOLL_CTL_DEL, s, NULL);
close(s);
bitmap_clear(udp_act[v6 ? V6 : V4][type], port);
}
}
/**
* udp_port_rebind() - Rebind ports to match forward maps
* @c: Execution context
* @outbound: True to remap outbound forwards, otherwise inbound
*
* Must be called in namespace context if @outbound is true.
*/
static void udp_port_rebind(struct ctx *c, bool outbound)
{
const uint8_t *fmap
= outbound ? c->udp.fwd_out.f.map : c->udp.fwd_in.f.map;
const uint8_t *rmap
= outbound ? c->udp.fwd_in.f.map : c->udp.fwd_out.f.map;
struct udp_splice_port (*socks)[NUM_PORTS]
= outbound ? udp_splice_ns : udp_splice_init;
unsigned port;
for (port = 0; port < NUM_PORTS; port++) {
if (!bitmap_isset(fmap, port)) {
if (socks[V4][port].sock >= 0) {
close(socks[V4][port].sock);
socks[V4][port].sock = -1;
}
if (socks[V6][port].sock >= 0) {
close(socks[V6][port].sock);
socks[V6][port].sock = -1;
}
continue;
}
/* Don't loop back our own ports */
if (bitmap_isset(rmap, port))
continue;
if ((c->ifi4 && socks[V4][port].sock == -1) ||
(c->ifi6 && socks[V6][port].sock == -1))
udp_sock_init(c, outbound, AF_UNSPEC, NULL, NULL, port);
}
}
/**
* udp_port_rebind_outbound() - Rebind ports in namespace
* @arg: Execution context
*
* Called with NS_CALL()
*
* Return: 0
*/
static int udp_port_rebind_outbound(void *arg)
{
struct ctx *c = (struct ctx *)arg;
ns_enter(c);
udp_port_rebind(c, true);
return 0;
}
/**
* udp_timer() - Scan activity bitmaps for ports with associated timed events
* @c: Execution context
* @now: Current timestamp
*/
void udp_timer(struct ctx *c, const struct timespec *now)
{
int n, t, v6 = 0;
unsigned int i;
long *word, tmp;
ASSERT(!c->no_udp);
if (c->mode == MODE_PASTA) {
if (c->udp.fwd_out.f.mode == FWD_AUTO) {
fwd_scan_ports_udp(&c->udp.fwd_out.f, &c->udp.fwd_in.f,
&c->tcp.fwd_out, &c->tcp.fwd_in);
NS_CALL(udp_port_rebind_outbound, c);
}
if (c->udp.fwd_in.f.mode == FWD_AUTO) {
fwd_scan_ports_udp(&c->udp.fwd_in.f, &c->udp.fwd_out.f,
&c->tcp.fwd_in, &c->tcp.fwd_out);
udp_port_rebind(c, false);
}
}
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, now);
}
}
}
if (!v6 && c->ifi6) {
v6 = 1;
goto v6;
}
}
/**
* udp_init() - Initialise per-socket data, and sockets in namespace
* @c: Execution context
*
* Return: 0
*/
int udp_init(struct ctx *c)
{
ASSERT(!c->no_udp);
udp_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();
NS_CALL(udp_port_rebind_outbound, c);
}
return 0;
}
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