freebsd-dev/sys/netinet/tcp_fastopen.c
Patrick Kelsey ec93ed8d95 Fix VIMAGE-related bugs in TFO. The autokey callout vnet context was
not being initialized, and the per-vnet fastopen context was only
being initialized for the default vnet.

PR:		216613
Reported by:	Alex Deiter <alex dot deiter at gmail dot com>
MFC after:	1 week
2017-02-03 17:02:57 +00:00

445 lines
14 KiB
C

/*-
* Copyright (c) 2015 Patrick Kelsey
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* This is a server-side implementation of TCP Fast Open (TFO) [RFC7413].
*
* This implementation is currently considered to be experimental and is not
* included in kernel builds by default. To include this code, add the
* following line to your kernel config:
*
* options TCP_RFC7413
*
* The generated TFO cookies are the 64-bit output of
* SipHash24(<16-byte-key><client-ip>). Multiple concurrent valid keys are
* supported so that time-based rolling cookie invalidation policies can be
* implemented in the system. The default number of concurrent keys is 2.
* This can be adjusted in the kernel config as follows:
*
* options TCP_RFC7413_MAX_KEYS=<num-keys>
*
*
* The following TFO-specific sysctls are defined:
*
* net.inet.tcp.fastopen.acceptany (RW, default 0)
* When non-zero, all client-supplied TFO cookies will be considered to
* be valid.
*
* net.inet.tcp.fastopen.autokey (RW, default 120)
* When this and net.inet.tcp.fastopen.enabled are non-zero, a new key
* will be automatically generated after this many seconds.
*
* net.inet.tcp.fastopen.enabled (RW, default 0)
* When zero, no new TFO connections can be created. On the transition
* from enabled to disabled, all installed keys are removed. On the
* transition from disabled to enabled, if net.inet.tcp.fastopen.autokey
* is non-zero and there are no keys installed, a new key will be
* generated immediately. The transition from enabled to disabled does
* not affect any TFO connections in progress; it only prevents new ones
* from being made.
*
* net.inet.tcp.fastopen.keylen (RO)
* The key length in bytes.
*
* net.inet.tcp.fastopen.maxkeys (RO)
* The maximum number of keys supported.
*
* net.inet.tcp.fastopen.numkeys (RO)
* The current number of keys installed.
*
* net.inet.tcp.fastopen.setkey (WO)
* Install a new key by writing net.inet.tcp.fastopen.keylen bytes to this
* sysctl.
*
*
* In order for TFO connections to be created via a listen socket, that
* socket must have the TCP_FASTOPEN socket option set on it. This option
* can be set on the socket either before or after the listen() is invoked.
* Clearing this option on a listen socket after it has been set has no
* effect on existing TFO connections or TFO connections in progress; it
* only prevents new TFO connections from being made.
*
* For passively-created sockets, the TCP_FASTOPEN socket option can be
* queried to determine whether the connection was established using TFO.
* Note that connections that are established via a TFO SYN, but that fall
* back to using a non-TFO SYN|ACK will have the TCP_FASTOPEN socket option
* set.
*
* Per the RFC, this implementation limits the number of TFO connections
* that can be in the SYN_RECEIVED state on a per listen-socket basis.
* Whenever this limit is exceeded, requests for new TFO connections are
* serviced as non-TFO requests. Without such a limit, given a valid TFO
* cookie, an attacker could keep the listen queue in an overflow condition
* using a TFO SYN flood. This implementation sets the limit at half the
* configured listen backlog.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_inet.h"
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/rmlock.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/sysctl.h>
#include <sys/systm.h>
#include <crypto/siphash/siphash.h>
#include <net/vnet.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/tcp_fastopen.h>
#include <netinet/tcp_var.h>
#define TCP_FASTOPEN_KEY_LEN SIPHASH_KEY_LENGTH
#if !defined(TCP_RFC7413_MAX_KEYS) || (TCP_RFC7413_MAX_KEYS < 1)
#define TCP_FASTOPEN_MAX_KEYS 2
#else
#define TCP_FASTOPEN_MAX_KEYS TCP_RFC7413_MAX_KEYS
#endif
struct tcp_fastopen_keylist {
unsigned int newest;
uint8_t key[TCP_FASTOPEN_MAX_KEYS][TCP_FASTOPEN_KEY_LEN];
};
struct tcp_fastopen_callout {
struct callout c;
struct vnet *v;
};
SYSCTL_NODE(_net_inet_tcp, OID_AUTO, fastopen, CTLFLAG_RW, 0, "TCP Fast Open");
static VNET_DEFINE(int, tcp_fastopen_acceptany) = 0;
#define V_tcp_fastopen_acceptany VNET(tcp_fastopen_acceptany)
SYSCTL_INT(_net_inet_tcp_fastopen, OID_AUTO, acceptany,
CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(tcp_fastopen_acceptany), 0,
"Accept any non-empty cookie");
static VNET_DEFINE(unsigned int, tcp_fastopen_autokey) = 120;
#define V_tcp_fastopen_autokey VNET(tcp_fastopen_autokey)
static int sysctl_net_inet_tcp_fastopen_autokey(SYSCTL_HANDLER_ARGS);
SYSCTL_PROC(_net_inet_tcp_fastopen, OID_AUTO, autokey,
CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW, NULL, 0,
&sysctl_net_inet_tcp_fastopen_autokey, "IU",
"Number of seconds between auto-generation of a new key; zero disables");
VNET_DEFINE(unsigned int, tcp_fastopen_enabled) = 0;
static int sysctl_net_inet_tcp_fastopen_enabled(SYSCTL_HANDLER_ARGS);
SYSCTL_PROC(_net_inet_tcp_fastopen, OID_AUTO, enabled,
CTLFLAG_VNET | CTLTYPE_UINT | CTLFLAG_RW, NULL, 0,
&sysctl_net_inet_tcp_fastopen_enabled, "IU",
"Enable/disable TCP Fast Open processing");
SYSCTL_INT(_net_inet_tcp_fastopen, OID_AUTO, keylen,
CTLFLAG_RD, SYSCTL_NULL_INT_PTR, TCP_FASTOPEN_KEY_LEN,
"Key length in bytes");
SYSCTL_INT(_net_inet_tcp_fastopen, OID_AUTO, maxkeys,
CTLFLAG_RD, SYSCTL_NULL_INT_PTR, TCP_FASTOPEN_MAX_KEYS,
"Maximum number of keys supported");
static VNET_DEFINE(unsigned int, tcp_fastopen_numkeys) = 0;
#define V_tcp_fastopen_numkeys VNET(tcp_fastopen_numkeys)
SYSCTL_UINT(_net_inet_tcp_fastopen, OID_AUTO, numkeys,
CTLFLAG_VNET | CTLFLAG_RD, &VNET_NAME(tcp_fastopen_numkeys), 0,
"Number of keys installed");
static int sysctl_net_inet_tcp_fastopen_setkey(SYSCTL_HANDLER_ARGS);
SYSCTL_PROC(_net_inet_tcp_fastopen, OID_AUTO, setkey,
CTLFLAG_VNET | CTLTYPE_OPAQUE | CTLFLAG_WR, NULL, 0,
&sysctl_net_inet_tcp_fastopen_setkey, "",
"Install a new key");
static VNET_DEFINE(struct rmlock, tcp_fastopen_keylock);
#define V_tcp_fastopen_keylock VNET(tcp_fastopen_keylock)
#define TCP_FASTOPEN_KEYS_RLOCK(t) rm_rlock(&V_tcp_fastopen_keylock, (t))
#define TCP_FASTOPEN_KEYS_RUNLOCK(t) rm_runlock(&V_tcp_fastopen_keylock, (t))
#define TCP_FASTOPEN_KEYS_WLOCK() rm_wlock(&V_tcp_fastopen_keylock)
#define TCP_FASTOPEN_KEYS_WUNLOCK() rm_wunlock(&V_tcp_fastopen_keylock)
static VNET_DEFINE(struct tcp_fastopen_keylist, tcp_fastopen_keys);
#define V_tcp_fastopen_keys VNET(tcp_fastopen_keys)
static VNET_DEFINE(struct tcp_fastopen_callout, tcp_fastopen_autokey_ctx);
#define V_tcp_fastopen_autokey_ctx VNET(tcp_fastopen_autokey_ctx)
static VNET_DEFINE(uma_zone_t, counter_zone);
#define V_counter_zone VNET(counter_zone)
void
tcp_fastopen_init(void)
{
V_counter_zone = uma_zcreate("tfo", sizeof(unsigned int),
NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
rm_init(&V_tcp_fastopen_keylock, "tfo_keylock");
callout_init_rm(&V_tcp_fastopen_autokey_ctx.c,
&V_tcp_fastopen_keylock, 0);
V_tcp_fastopen_autokey_ctx.v = curvnet;
V_tcp_fastopen_keys.newest = TCP_FASTOPEN_MAX_KEYS - 1;
}
void
tcp_fastopen_destroy(void)
{
callout_drain(&V_tcp_fastopen_autokey_ctx.c);
rm_destroy(&V_tcp_fastopen_keylock);
uma_zdestroy(V_counter_zone);
}
unsigned int *
tcp_fastopen_alloc_counter(void)
{
unsigned int *counter;
counter = uma_zalloc(V_counter_zone, M_NOWAIT);
if (counter)
*counter = 1;
return (counter);
}
void
tcp_fastopen_decrement_counter(unsigned int *counter)
{
if (*counter == 1)
uma_zfree(V_counter_zone, counter);
else
atomic_subtract_int(counter, 1);
}
static void
tcp_fastopen_addkey_locked(uint8_t *key)
{
V_tcp_fastopen_keys.newest++;
if (V_tcp_fastopen_keys.newest == TCP_FASTOPEN_MAX_KEYS)
V_tcp_fastopen_keys.newest = 0;
memcpy(V_tcp_fastopen_keys.key[V_tcp_fastopen_keys.newest], key,
TCP_FASTOPEN_KEY_LEN);
if (V_tcp_fastopen_numkeys < TCP_FASTOPEN_MAX_KEYS)
V_tcp_fastopen_numkeys++;
}
static void
tcp_fastopen_autokey_locked(void)
{
uint8_t newkey[TCP_FASTOPEN_KEY_LEN];
arc4rand(newkey, TCP_FASTOPEN_KEY_LEN, 0);
tcp_fastopen_addkey_locked(newkey);
}
static void
tcp_fastopen_autokey_callout(void *arg)
{
struct tcp_fastopen_callout *ctx = arg;
CURVNET_SET(ctx->v);
tcp_fastopen_autokey_locked();
callout_reset(&ctx->c, V_tcp_fastopen_autokey * hz,
tcp_fastopen_autokey_callout, ctx);
CURVNET_RESTORE();
}
static uint64_t
tcp_fastopen_make_cookie(uint8_t key[SIPHASH_KEY_LENGTH], struct in_conninfo *inc)
{
SIPHASH_CTX ctx;
uint64_t siphash;
SipHash24_Init(&ctx);
SipHash_SetKey(&ctx, key);
switch (inc->inc_flags & INC_ISIPV6) {
#ifdef INET
case 0:
SipHash_Update(&ctx, &inc->inc_faddr, sizeof(inc->inc_faddr));
break;
#endif
#ifdef INET6
case INC_ISIPV6:
SipHash_Update(&ctx, &inc->inc6_faddr, sizeof(inc->inc6_faddr));
break;
#endif
}
SipHash_Final((u_int8_t *)&siphash, &ctx);
return (siphash);
}
/*
* Return values:
* -1 the cookie is invalid and no valid cookie is available
* 0 the cookie is invalid and the latest cookie has been returned
* 1 the cookie is valid and the latest cookie has been returned
*/
int
tcp_fastopen_check_cookie(struct in_conninfo *inc, uint8_t *cookie,
unsigned int len, uint64_t *latest_cookie)
{
struct rm_priotracker tracker;
unsigned int i, key_index;
uint64_t cur_cookie;
if (V_tcp_fastopen_acceptany) {
*latest_cookie = 0;
return (1);
}
if (len != TCP_FASTOPEN_COOKIE_LEN) {
if (V_tcp_fastopen_numkeys > 0) {
*latest_cookie =
tcp_fastopen_make_cookie(
V_tcp_fastopen_keys.key[V_tcp_fastopen_keys.newest],
inc);
return (0);
}
return (-1);
}
/*
* Check against each available key, from newest to oldest.
*/
TCP_FASTOPEN_KEYS_RLOCK(&tracker);
key_index = V_tcp_fastopen_keys.newest;
for (i = 0; i < V_tcp_fastopen_numkeys; i++) {
cur_cookie =
tcp_fastopen_make_cookie(V_tcp_fastopen_keys.key[key_index],
inc);
if (i == 0)
*latest_cookie = cur_cookie;
if (memcmp(cookie, &cur_cookie, TCP_FASTOPEN_COOKIE_LEN) == 0) {
TCP_FASTOPEN_KEYS_RUNLOCK(&tracker);
return (1);
}
if (key_index == 0)
key_index = TCP_FASTOPEN_MAX_KEYS - 1;
else
key_index--;
}
TCP_FASTOPEN_KEYS_RUNLOCK(&tracker);
return (0);
}
static int
sysctl_net_inet_tcp_fastopen_autokey(SYSCTL_HANDLER_ARGS)
{
int error;
unsigned int new;
new = V_tcp_fastopen_autokey;
error = sysctl_handle_int(oidp, &new, 0, req);
if (error == 0 && req->newptr) {
if (new > (INT_MAX / hz))
return (EINVAL);
TCP_FASTOPEN_KEYS_WLOCK();
if (V_tcp_fastopen_enabled) {
if (V_tcp_fastopen_autokey && !new)
callout_stop(&V_tcp_fastopen_autokey_ctx.c);
else if (new)
callout_reset(&V_tcp_fastopen_autokey_ctx.c,
new * hz, tcp_fastopen_autokey_callout,
&V_tcp_fastopen_autokey_ctx);
}
V_tcp_fastopen_autokey = new;
TCP_FASTOPEN_KEYS_WUNLOCK();
}
return (error);
}
static int
sysctl_net_inet_tcp_fastopen_enabled(SYSCTL_HANDLER_ARGS)
{
int error;
unsigned int new;
new = V_tcp_fastopen_enabled;
error = sysctl_handle_int(oidp, &new, 0, req);
if (error == 0 && req->newptr) {
if (V_tcp_fastopen_enabled && !new) {
/* enabled -> disabled */
TCP_FASTOPEN_KEYS_WLOCK();
V_tcp_fastopen_numkeys = 0;
V_tcp_fastopen_keys.newest = TCP_FASTOPEN_MAX_KEYS - 1;
if (V_tcp_fastopen_autokey)
callout_stop(&V_tcp_fastopen_autokey_ctx.c);
V_tcp_fastopen_enabled = 0;
TCP_FASTOPEN_KEYS_WUNLOCK();
} else if (!V_tcp_fastopen_enabled && new) {
/* disabled -> enabled */
TCP_FASTOPEN_KEYS_WLOCK();
if (V_tcp_fastopen_autokey &&
(V_tcp_fastopen_numkeys == 0)) {
tcp_fastopen_autokey_locked();
callout_reset(&V_tcp_fastopen_autokey_ctx.c,
V_tcp_fastopen_autokey * hz,
tcp_fastopen_autokey_callout,
&V_tcp_fastopen_autokey_ctx);
}
V_tcp_fastopen_enabled = 1;
TCP_FASTOPEN_KEYS_WUNLOCK();
}
}
return (error);
}
static int
sysctl_net_inet_tcp_fastopen_setkey(SYSCTL_HANDLER_ARGS)
{
int error;
uint8_t newkey[TCP_FASTOPEN_KEY_LEN];
if (req->oldptr != NULL || req->oldlen != 0)
return (EINVAL);
if (req->newptr == NULL)
return (EPERM);
if (req->newlen != sizeof(newkey))
return (EINVAL);
error = SYSCTL_IN(req, newkey, sizeof(newkey));
if (error)
return (error);
TCP_FASTOPEN_KEYS_WLOCK();
tcp_fastopen_addkey_locked(newkey);
TCP_FASTOPEN_KEYS_WUNLOCK();
return (0);
}