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qemu/net/l2tpv3.c
Christian Svensson 0c65ef4fbb net: Increase L2TPv3 buffer to fit jumboframes 
Increase the allocated buffer size to fit larger packets.
Given that jumboframes can commonly be up to 9000 bytes the closest suitable
value seems to be 16 KiB.

Tested by running qemu towards a Linux L2TPv3 endpoint and pushing
jumboframe traffic through the interfaces.

Signed-off-by: Christian Svensson <blue@cmd.nu>
Signed-off-by: Jason Wang <jasowang@redhat.com>
2023-02-17 13:31:33 +08:00

731 lines
19 KiB
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/*
* QEMU System Emulator
*
* Copyright (c) 2003-2008 Fabrice Bellard
* Copyright (c) 2012-2014 Cisco Systems
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include <linux/ip.h>
#include <netdb.h>
#include "net/net.h"
#include "clients.h"
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "qemu/option.h"
#include "qemu/sockets.h"
#include "qemu/iov.h"
#include "qemu/main-loop.h"
#include "qemu/memalign.h"
/* The buffer size needs to be investigated for optimum numbers and
* optimum means of paging in on different systems. This size is
* chosen to be sufficient to accommodate one packet with some headers
*/
#define BUFFER_ALIGN sysconf(_SC_PAGESIZE)
#define BUFFER_SIZE 16384
#define IOVSIZE 2
#define MAX_L2TPV3_MSGCNT 64
#define MAX_L2TPV3_IOVCNT (MAX_L2TPV3_MSGCNT * IOVSIZE)
/* Header set to 0x30000 signifies a data packet */
#define L2TPV3_DATA_PACKET 0x30000
/* IANA-assigned IP protocol ID for L2TPv3 */
#ifndef IPPROTO_L2TP
#define IPPROTO_L2TP 0x73
#endif
typedef struct NetL2TPV3State {
NetClientState nc;
int fd;
/*
* these are used for xmit - that happens packet a time
* and for first sign of life packet (easier to parse that once)
*/
uint8_t *header_buf;
struct iovec *vec;
/*
* these are used for receive - try to "eat" up to 32 packets at a time
*/
struct mmsghdr *msgvec;
/*
* peer address
*/
struct sockaddr_storage *dgram_dst;
uint32_t dst_size;
/*
* L2TPv3 parameters
*/
uint64_t rx_cookie;
uint64_t tx_cookie;
uint32_t rx_session;
uint32_t tx_session;
uint32_t header_size;
uint32_t counter;
/*
* DOS avoidance in error handling
*/
bool header_mismatch;
/*
* Ring buffer handling
*/
int queue_head;
int queue_tail;
int queue_depth;
/*
* Precomputed offsets
*/
uint32_t offset;
uint32_t cookie_offset;
uint32_t counter_offset;
uint32_t session_offset;
/* Poll Control */
bool read_poll;
bool write_poll;
/* Flags */
bool ipv6;
bool udp;
bool has_counter;
bool pin_counter;
bool cookie;
bool cookie_is_64;
} NetL2TPV3State;
static void net_l2tpv3_send(void *opaque);
static void l2tpv3_writable(void *opaque);
static void l2tpv3_update_fd_handler(NetL2TPV3State *s)
{
qemu_set_fd_handler(s->fd,
s->read_poll ? net_l2tpv3_send : NULL,
s->write_poll ? l2tpv3_writable : NULL,
s);
}
static void l2tpv3_read_poll(NetL2TPV3State *s, bool enable)
{
if (s->read_poll != enable) {
s->read_poll = enable;
l2tpv3_update_fd_handler(s);
}
}
static void l2tpv3_write_poll(NetL2TPV3State *s, bool enable)
{
if (s->write_poll != enable) {
s->write_poll = enable;
l2tpv3_update_fd_handler(s);
}
}
static void l2tpv3_writable(void *opaque)
{
NetL2TPV3State *s = opaque;
l2tpv3_write_poll(s, false);
qemu_flush_queued_packets(&s->nc);
}
static void l2tpv3_send_completed(NetClientState *nc, ssize_t len)
{
NetL2TPV3State *s = DO_UPCAST(NetL2TPV3State, nc, nc);
l2tpv3_read_poll(s, true);
}
static void l2tpv3_poll(NetClientState *nc, bool enable)
{
NetL2TPV3State *s = DO_UPCAST(NetL2TPV3State, nc, nc);
l2tpv3_write_poll(s, enable);
l2tpv3_read_poll(s, enable);
}
static void l2tpv3_form_header(NetL2TPV3State *s)
{
uint32_t *counter;
if (s->udp) {
stl_be_p((uint32_t *) s->header_buf, L2TPV3_DATA_PACKET);
}
stl_be_p(
(uint32_t *) (s->header_buf + s->session_offset),
s->tx_session
);
if (s->cookie) {
if (s->cookie_is_64) {
stq_be_p(
(uint64_t *)(s->header_buf + s->cookie_offset),
s->tx_cookie
);
} else {
stl_be_p(
(uint32_t *) (s->header_buf + s->cookie_offset),
s->tx_cookie
);
}
}
if (s->has_counter) {
counter = (uint32_t *)(s->header_buf + s->counter_offset);
if (s->pin_counter) {
*counter = 0;
} else {
stl_be_p(counter, ++s->counter);
}
}
}
static ssize_t net_l2tpv3_receive_dgram_iov(NetClientState *nc,
const struct iovec *iov,
int iovcnt)
{
NetL2TPV3State *s = DO_UPCAST(NetL2TPV3State, nc, nc);
struct msghdr message;
int ret;
if (iovcnt > MAX_L2TPV3_IOVCNT - 1) {
error_report(
"iovec too long %d > %d, change l2tpv3.h",
iovcnt, MAX_L2TPV3_IOVCNT
);
return -1;
}
l2tpv3_form_header(s);
memcpy(s->vec + 1, iov, iovcnt * sizeof(struct iovec));
s->vec->iov_base = s->header_buf;
s->vec->iov_len = s->offset;
message.msg_name = s->dgram_dst;
message.msg_namelen = s->dst_size;
message.msg_iov = s->vec;
message.msg_iovlen = iovcnt + 1;
message.msg_control = NULL;
message.msg_controllen = 0;
message.msg_flags = 0;
ret = RETRY_ON_EINTR(sendmsg(s->fd, &message, 0));
if (ret > 0) {
ret -= s->offset;
} else if (ret == 0) {
/* belt and braces - should not occur on DGRAM
* we should get an error and never a 0 send
*/
ret = iov_size(iov, iovcnt);
} else {
/* signal upper layer that socket buffer is full */
ret = -errno;
if (ret == -EAGAIN || ret == -ENOBUFS) {
l2tpv3_write_poll(s, true);
ret = 0;
}
}
return ret;
}
static ssize_t net_l2tpv3_receive_dgram(NetClientState *nc,
const uint8_t *buf,
size_t size)
{
NetL2TPV3State *s = DO_UPCAST(NetL2TPV3State, nc, nc);
struct iovec *vec;
struct msghdr message;
ssize_t ret = 0;
l2tpv3_form_header(s);
vec = s->vec;
vec->iov_base = s->header_buf;
vec->iov_len = s->offset;
vec++;
vec->iov_base = (void *) buf;
vec->iov_len = size;
message.msg_name = s->dgram_dst;
message.msg_namelen = s->dst_size;
message.msg_iov = s->vec;
message.msg_iovlen = 2;
message.msg_control = NULL;
message.msg_controllen = 0;
message.msg_flags = 0;
ret = RETRY_ON_EINTR(sendmsg(s->fd, &message, 0));
if (ret > 0) {
ret -= s->offset;
} else if (ret == 0) {
/* belt and braces - should not occur on DGRAM
* we should get an error and never a 0 send
*/
ret = size;
} else {
ret = -errno;
if (ret == -EAGAIN || ret == -ENOBUFS) {
/* signal upper layer that socket buffer is full */
l2tpv3_write_poll(s, true);
ret = 0;
}
}
return ret;
}
static int l2tpv3_verify_header(NetL2TPV3State *s, uint8_t *buf)
{
uint32_t *session;
uint64_t cookie;
if ((!s->udp) && (!s->ipv6)) {
buf += sizeof(struct iphdr) /* fix for ipv4 raw */;
}
/* we do not do a strict check for "data" packets as per
* the RFC spec because the pure IP spec does not have
* that anyway.
*/
if (s->cookie) {
if (s->cookie_is_64) {
cookie = ldq_be_p(buf + s->cookie_offset);
} else {
cookie = ldl_be_p(buf + s->cookie_offset) & 0xffffffffULL;
}
if (cookie != s->rx_cookie) {
if (!s->header_mismatch) {
error_report("unknown cookie id");
}
return -1;
}
}
session = (uint32_t *) (buf + s->session_offset);
if (ldl_be_p(session) != s->rx_session) {
if (!s->header_mismatch) {
error_report("session mismatch");
}
return -1;
}
return 0;
}
static void net_l2tpv3_process_queue(NetL2TPV3State *s)
{
int size = 0;
struct iovec *vec;
bool bad_read;
int data_size;
struct mmsghdr *msgvec;
/* go into ring mode only if there is a "pending" tail */
if (s->queue_depth > 0) {
do {
msgvec = s->msgvec + s->queue_tail;
if (msgvec->msg_len > 0) {
data_size = msgvec->msg_len - s->header_size;
vec = msgvec->msg_hdr.msg_iov;
if ((data_size > 0) &&
(l2tpv3_verify_header(s, vec->iov_base) == 0)) {
vec++;
/* Use the legacy delivery for now, we will
* switch to using our own ring as a queueing mechanism
* at a later date
*/
size = qemu_send_packet_async(
&s->nc,
vec->iov_base,
data_size,
l2tpv3_send_completed
);
if (size == 0) {
l2tpv3_read_poll(s, false);
}
bad_read = false;
} else {
bad_read = true;
if (!s->header_mismatch) {
/* report error only once */
error_report("l2tpv3 header verification failed");
s->header_mismatch = true;
}
}
} else {
bad_read = true;
}
s->queue_tail = (s->queue_tail + 1) % MAX_L2TPV3_MSGCNT;
s->queue_depth--;
} while (
(s->queue_depth > 0) &&
qemu_can_send_packet(&s->nc) &&
((size > 0) || bad_read)
);
}
}
static void net_l2tpv3_send(void *opaque)
{
NetL2TPV3State *s = opaque;
int target_count, count;
struct mmsghdr *msgvec;
/* go into ring mode only if there is a "pending" tail */
if (s->queue_depth) {
/* The ring buffer we use has variable intake
* count of how much we can read varies - adjust accordingly
*/
target_count = MAX_L2TPV3_MSGCNT - s->queue_depth;
/* Ensure we do not overrun the ring when we have
* a lot of enqueued packets
*/
if (s->queue_head + target_count > MAX_L2TPV3_MSGCNT) {
target_count = MAX_L2TPV3_MSGCNT - s->queue_head;
}
} else {
/* we do not have any pending packets - we can use
* the whole message vector linearly instead of using
* it as a ring
*/
s->queue_head = 0;
s->queue_tail = 0;
target_count = MAX_L2TPV3_MSGCNT;
}
msgvec = s->msgvec + s->queue_head;
if (target_count > 0) {
count = RETRY_ON_EINTR(
recvmmsg(s->fd, msgvec, target_count, MSG_DONTWAIT, NULL)
);
if (count < 0) {
/* Recv error - we still need to flush packets here,
* (re)set queue head to current position
*/
count = 0;
}
s->queue_head = (s->queue_head + count) % MAX_L2TPV3_MSGCNT;
s->queue_depth += count;
}
net_l2tpv3_process_queue(s);
}
static void destroy_vector(struct mmsghdr *msgvec, int count, int iovcount)
{
int i, j;
struct iovec *iov;
struct mmsghdr *cleanup = msgvec;
if (cleanup) {
for (i = 0; i < count; i++) {
if (cleanup->msg_hdr.msg_iov) {
iov = cleanup->msg_hdr.msg_iov;
for (j = 0; j < iovcount; j++) {
g_free(iov->iov_base);
iov++;
}
g_free(cleanup->msg_hdr.msg_iov);
}
cleanup++;
}
g_free(msgvec);
}
}
static struct mmsghdr *build_l2tpv3_vector(NetL2TPV3State *s, int count)
{
int i;
struct iovec *iov;
struct mmsghdr *msgvec, *result;
msgvec = g_new(struct mmsghdr, count);
result = msgvec;
for (i = 0; i < count ; i++) {
msgvec->msg_hdr.msg_name = NULL;
msgvec->msg_hdr.msg_namelen = 0;
iov = g_new(struct iovec, IOVSIZE);
msgvec->msg_hdr.msg_iov = iov;
iov->iov_base = g_malloc(s->header_size);
iov->iov_len = s->header_size;
iov++ ;
iov->iov_base = qemu_memalign(BUFFER_ALIGN, BUFFER_SIZE);
iov->iov_len = BUFFER_SIZE;
msgvec->msg_hdr.msg_iovlen = 2;
msgvec->msg_hdr.msg_control = NULL;
msgvec->msg_hdr.msg_controllen = 0;
msgvec->msg_hdr.msg_flags = 0;
msgvec++;
}
return result;
}
static void net_l2tpv3_cleanup(NetClientState *nc)
{
NetL2TPV3State *s = DO_UPCAST(NetL2TPV3State, nc, nc);
qemu_purge_queued_packets(nc);
l2tpv3_read_poll(s, false);
l2tpv3_write_poll(s, false);
if (s->fd >= 0) {
close(s->fd);
}
destroy_vector(s->msgvec, MAX_L2TPV3_MSGCNT, IOVSIZE);
g_free(s->vec);
g_free(s->header_buf);
g_free(s->dgram_dst);
}
static NetClientInfo net_l2tpv3_info = {
.type = NET_CLIENT_DRIVER_L2TPV3,
.size = sizeof(NetL2TPV3State),
.receive = net_l2tpv3_receive_dgram,
.receive_iov = net_l2tpv3_receive_dgram_iov,
.poll = l2tpv3_poll,
.cleanup = net_l2tpv3_cleanup,
};
int net_init_l2tpv3(const Netdev *netdev,
const char *name,
NetClientState *peer, Error **errp)
{
const NetdevL2TPv3Options *l2tpv3;
NetL2TPV3State *s;
NetClientState *nc;
int fd = -1, gairet;
struct addrinfo hints;
struct addrinfo *result = NULL;
char *srcport, *dstport;
nc = qemu_new_net_client(&net_l2tpv3_info, peer, "l2tpv3", name);
s = DO_UPCAST(NetL2TPV3State, nc, nc);
s->queue_head = 0;
s->queue_tail = 0;
s->header_mismatch = false;
assert(netdev->type == NET_CLIENT_DRIVER_L2TPV3);
l2tpv3 = &netdev->u.l2tpv3;
if (l2tpv3->has_ipv6 && l2tpv3->ipv6) {
s->ipv6 = l2tpv3->ipv6;
} else {
s->ipv6 = false;
}
if ((l2tpv3->has_offset) && (l2tpv3->offset > 256)) {
error_setg(errp, "offset must be less than 256 bytes");
goto outerr;
}
if (l2tpv3->has_rxcookie || l2tpv3->has_txcookie) {
if (l2tpv3->has_rxcookie && l2tpv3->has_txcookie) {
s->cookie = true;
} else {
error_setg(errp,
"require both 'rxcookie' and 'txcookie' or neither");
goto outerr;
}
} else {
s->cookie = false;
}
if (l2tpv3->has_cookie64 || l2tpv3->cookie64) {
s->cookie_is_64 = true;
} else {
s->cookie_is_64 = false;
}
if (l2tpv3->has_udp && l2tpv3->udp) {
s->udp = true;
if (!(l2tpv3->srcport && l2tpv3->dstport)) {
error_setg(errp, "need both src and dst port for udp");
goto outerr;
} else {
srcport = l2tpv3->srcport;
dstport = l2tpv3->dstport;
}
} else {
s->udp = false;
srcport = NULL;
dstport = NULL;
}
s->offset = 4;
s->session_offset = 0;
s->cookie_offset = 4;
s->counter_offset = 4;
s->tx_session = l2tpv3->txsession;
if (l2tpv3->has_rxsession) {
s->rx_session = l2tpv3->rxsession;
} else {
s->rx_session = s->tx_session;
}
if (s->cookie) {
s->rx_cookie = l2tpv3->rxcookie;
s->tx_cookie = l2tpv3->txcookie;
if (s->cookie_is_64 == true) {
/* 64 bit cookie */
s->offset += 8;
s->counter_offset += 8;
} else {
/* 32 bit cookie */
s->offset += 4;
s->counter_offset += 4;
}
}
memset(&hints, 0, sizeof(hints));
if (s->ipv6) {
hints.ai_family = AF_INET6;
} else {
hints.ai_family = AF_INET;
}
if (s->udp) {
hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = 0;
s->offset += 4;
s->counter_offset += 4;
s->session_offset += 4;
s->cookie_offset += 4;
} else {
hints.ai_socktype = SOCK_RAW;
hints.ai_protocol = IPPROTO_L2TP;
}
gairet = getaddrinfo(l2tpv3->src, srcport, &hints, &result);
if ((gairet != 0) || (result == NULL)) {
error_setg(errp, "could not resolve src, errno = %s",
gai_strerror(gairet));
goto outerr;
}
fd = socket(result->ai_family, result->ai_socktype, result->ai_protocol);
if (fd == -1) {
fd = -errno;
error_setg(errp, "socket creation failed, errno = %d",
-fd);
goto outerr;
}
if (bind(fd, (struct sockaddr *) result->ai_addr, result->ai_addrlen)) {
error_setg(errp, "could not bind socket err=%i", errno);
goto outerr;
}
freeaddrinfo(result);
memset(&hints, 0, sizeof(hints));
if (s->ipv6) {
hints.ai_family = AF_INET6;
} else {
hints.ai_family = AF_INET;
}
if (s->udp) {
hints.ai_socktype = SOCK_DGRAM;
hints.ai_protocol = 0;
} else {
hints.ai_socktype = SOCK_RAW;
hints.ai_protocol = IPPROTO_L2TP;
}
result = NULL;
gairet = getaddrinfo(l2tpv3->dst, dstport, &hints, &result);
if ((gairet != 0) || (result == NULL)) {
error_setg(errp, "could not resolve dst, error = %s",
gai_strerror(gairet));
goto outerr;
}
s->dgram_dst = g_new0(struct sockaddr_storage, 1);
memcpy(s->dgram_dst, result->ai_addr, result->ai_addrlen);
s->dst_size = result->ai_addrlen;
freeaddrinfo(result);
if (l2tpv3->has_counter && l2tpv3->counter) {
s->has_counter = true;
s->offset += 4;
} else {
s->has_counter = false;
}
if (l2tpv3->has_pincounter && l2tpv3->pincounter) {
s->has_counter = true; /* pin counter implies that there is counter */
s->pin_counter = true;
} else {
s->pin_counter = false;
}
if (l2tpv3->has_offset) {
/* extra offset */
s->offset += l2tpv3->offset;
}
if ((s->ipv6) || (s->udp)) {
s->header_size = s->offset;
} else {
s->header_size = s->offset + sizeof(struct iphdr);
}
s->msgvec = build_l2tpv3_vector(s, MAX_L2TPV3_MSGCNT);
s->vec = g_new(struct iovec, MAX_L2TPV3_IOVCNT);
s->header_buf = g_malloc(s->header_size);
qemu_socket_set_nonblock(fd);
s->fd = fd;
s->counter = 0;
l2tpv3_read_poll(s, true);
qemu_set_info_str(&s->nc, "l2tpv3: connected");
return 0;
outerr:
qemu_del_net_client(nc);
if (fd >= 0) {
close(fd);
}
if (result) {
freeaddrinfo(result);
}
return -1;
}
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