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freebsd-skq/sys/netgraph/ng_l2tp.c

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/*
* Copyright (c) 2001-2002 Packet Design, LLC.
* All rights reserved.
*
* Subject to the following obligations and disclaimer of warranty,
* use and redistribution of this software, in source or object code
* forms, with or without modifications are expressly permitted by
* Packet Design; provided, however, that:
*
* (i) Any and all reproductions of the source or object code
* must include the copyright notice above and the following
* disclaimer of warranties; and
* (ii) No rights are granted, in any manner or form, to use
* Packet Design trademarks, including the mark "PACKET DESIGN"
* on advertising, endorsements, or otherwise except as such
* appears in the above copyright notice or in the software.
*
* THIS SOFTWARE IS BEING PROVIDED BY PACKET DESIGN "AS IS", AND
* TO THE MAXIMUM EXTENT PERMITTED BY LAW, PACKET DESIGN MAKES NO
* REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING
* THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED
* WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,
* OR NON-INFRINGEMENT. PACKET DESIGN DOES NOT WARRANT, GUARANTEE,
* OR MAKE ANY REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS
* OF THE USE OF THIS SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY,
* RELIABILITY OR OTHERWISE. IN NO EVENT SHALL PACKET DESIGN BE
* LIABLE FOR ANY DAMAGES RESULTING FROM OR ARISING OUT OF ANY USE
* OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, PUNITIVE, OR CONSEQUENTIAL
* DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, LOSS OF
* USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER 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 PACKET DESIGN IS ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*
* Author: Archie Cobbs <archie@freebsd.org>
*
* $FreeBSD$
*/
/*
* L2TP netgraph node type.
*
* This node type implements the lower layer of the
* L2TP protocol as specified in RFC 2661.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/time.h>
#include <sys/conf.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/errno.h>
#include <netgraph/ng_message.h>
#include <netgraph/netgraph.h>
#include <netgraph/ng_parse.h>
#include <netgraph/ng_l2tp.h>
#ifdef NG_SEPARATE_MALLOC
MALLOC_DEFINE(M_NETGRAPH_L2TP, "netgraph_l2tp", "netgraph l2tp node");
#else
#define M_NETGRAPH_L2TP M_NETGRAPH
#endif
/* L2TP header format (first 2 bytes only) */
#define L2TP_HDR_CTRL 0x8000 /* control packet */
#define L2TP_HDR_LEN 0x4000 /* has length field */
#define L2TP_HDR_SEQ 0x0800 /* has ns, nr fields */
#define L2TP_HDR_OFF 0x0200 /* has offset field */
#define L2TP_HDR_PRIO 0x0100 /* give priority */
#define L2TP_HDR_VERS_MASK 0x000f /* version field mask */
#define L2TP_HDR_VERSION 0x0002 /* version field */
/* Bits that must be zero or one in first two bytes of header */
#define L2TP_CTRL_0BITS 0x030d /* ctrl: must be 0 */
#define L2TP_CTRL_1BITS 0xc802 /* ctrl: must be 1 */
#define L2TP_DATA_0BITS 0x800d /* data: must be 0 */
#define L2TP_DATA_1BITS 0x0002 /* data: must be 1 */
/* Standard xmit ctrl and data header bits */
#define L2TP_CTRL_HDR (L2TP_HDR_CTRL | L2TP_HDR_LEN \
| L2TP_HDR_SEQ | L2TP_HDR_VERSION)
#define L2TP_DATA_HDR (L2TP_HDR_VERSION) /* optional: len, seq */
/* Some hard coded values */
#define L2TP_MAX_XWIN 16 /* my max xmit window */
#define L2TP_MAX_REXMIT 5 /* default max rexmit */
#define L2TP_MAX_REXMIT_TO 30 /* default rexmit to */
#define L2TP_DELAYED_ACK ((hz + 19) / 20) /* delayed ack: 50 ms */
/* Default data sequence number configuration for new sessions */
#define L2TP_CONTROL_DSEQ 1 /* we are the lns */
#define L2TP_ENABLE_DSEQ 1 /* enable data seq # */
/* Compare sequence numbers using circular math */
#define L2TP_SEQ_DIFF(x, y) ((int)((int16_t)(x) - (int16_t)(y)))
/*
* Sequence number state
*
* Invariants:
* - If cwnd < ssth, we're doing slow start, otherwise congestion avoidance
* - The number of unacknowledged xmit packets is (ns - rack) <= seq->wmax
* - The first (ns - rack) mbuf's in xwin[] array are copies of these
* unacknowledged packets; the remainder of xwin[] consists first of
* zero or more further untransmitted packets in the transmit queue
* - We try to keep the peer's receive window as full as possible.
* Therefore, (i < cwnd && xwin[i] != NULL) implies (ns - rack) > i.
* - rack_timer is running iff (ns - rack) > 0 (unack'd xmit'd pkts)
* - If xack != nr, there are unacknowledged recv packet(s) (delayed ack)
* - xack_timer is running iff xack != nr (unack'd rec'd pkts)
*/
struct l2tp_seq {
u_int16_t ns; /* next xmit seq we send */
u_int16_t nr; /* next recv seq we expect */
u_int16_t rack; /* last 'nr' we rec'd */
u_int16_t xack; /* last 'nr' we sent */
u_int16_t wmax; /* peer's max recv window */
u_int16_t cwnd; /* current congestion window */
u_int16_t ssth; /* slow start threshold */
u_int16_t acks; /* # consecutive acks rec'd */
u_int16_t rexmits; /* # retransmits sent */
u_int16_t max_rexmits; /* max # retransmits sent */
u_int16_t max_rexmit_to; /* max retransmit timeout */
struct callout rack_timer; /* retransmit timer */
struct callout xack_timer; /* delayed ack timer */
u_char rack_timer_running; /* xmit timer running */
u_char xack_timer_running; /* ack timer running */
struct mbuf *xwin[L2TP_MAX_XWIN]; /* transmit window */
};
/* Node private data */
struct ng_l2tp_private {
node_p node; /* back pointer to node */
hook_p ctrl; /* hook to upper layers */
hook_p lower; /* hook to lower layers */
struct ng_l2tp_config conf; /* node configuration */
struct ng_l2tp_stats stats; /* node statistics */
struct l2tp_seq seq; /* ctrl sequence number state */
ng_ID_t ftarget; /* failure message target */
};
typedef struct ng_l2tp_private *priv_p;
/* Hook private data (data session hooks only) */
struct ng_l2tp_hook_private {
struct ng_l2tp_sess_config conf; /* hook/session config */
u_int16_t ns; /* data ns sequence number */
u_int16_t nr; /* data nr sequence number */
};
typedef struct ng_l2tp_hook_private *hookpriv_p;
/* Netgraph node methods */
static ng_constructor_t ng_l2tp_constructor;
static ng_rcvmsg_t ng_l2tp_rcvmsg;
static ng_shutdown_t ng_l2tp_shutdown;
static ng_newhook_t ng_l2tp_newhook;
static ng_rcvdata_t ng_l2tp_rcvdata;
static ng_disconnect_t ng_l2tp_disconnect;
/* Internal functions */
static int ng_l2tp_recv_lower(node_p node, item_p item);
static int ng_l2tp_recv_ctrl(node_p node, item_p item);
static int ng_l2tp_recv_data(node_p node, item_p item, hookpriv_p hpriv);
static int ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns);
static void ng_l2tp_seq_init(priv_p priv);
static int ng_l2tp_seq_adjust(priv_p priv,
const struct ng_l2tp_config *conf);
static void ng_l2tp_seq_reset(priv_p priv);
static void ng_l2tp_seq_failure(priv_p priv);
static void ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr);
static int ng_l2tp_seq_recv_ns(priv_p priv, u_int16_t ns);
static void ng_l2tp_seq_xack_timeout(void *arg);
static void ng_l2tp_seq_rack_timeout(void *arg);
static ng_fn_eachhook ng_l2tp_find_session;
static ng_fn_eachhook ng_l2tp_reset_session;
#ifdef INVARIANTS
static void ng_l2tp_seq_check(struct l2tp_seq *seq);
#endif
/* Parse type for struct ng_l2tp_config */
static const struct ng_parse_struct_field
ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO;
static const struct ng_parse_type ng_l2tp_config_type = {
&ng_parse_struct_type,
&ng_l2tp_config_type_fields,
};
/* Parse type for struct ng_l2tp_sess_config */
static const struct ng_parse_struct_field
ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO;
static const struct ng_parse_type ng_l2tp_sess_config_type = {
&ng_parse_struct_type,
&ng_l2tp_sess_config_type_fields,
};
/* Parse type for struct ng_l2tp_stats */
static const struct ng_parse_struct_field
ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO;
static const struct ng_parse_type ng_pptp_stats_type = {
&ng_parse_struct_type,
&ng_l2tp_stats_type_fields
};
/* List of commands and how to convert arguments to/from ASCII */
static const struct ng_cmdlist ng_l2tp_cmdlist[] = {
{
NGM_L2TP_COOKIE,
NGM_L2TP_SET_CONFIG,
"setconfig",
&ng_l2tp_config_type,
NULL
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_GET_CONFIG,
"getconfig",
NULL,
&ng_l2tp_config_type
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_SET_SESS_CONFIG,
"setsessconfig",
&ng_l2tp_sess_config_type,
NULL
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_GET_SESS_CONFIG,
"getsessconfig",
&ng_parse_hint16_type,
&ng_l2tp_sess_config_type
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_GET_STATS,
"getstats",
NULL,
&ng_pptp_stats_type
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_CLR_STATS,
"clrstats",
NULL,
NULL
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_GETCLR_STATS,
"getclrstats",
NULL,
&ng_pptp_stats_type
},
{
NGM_L2TP_COOKIE,
NGM_L2TP_ACK_FAILURE,
"ackfailure",
NULL,
NULL
},
{ 0 }
};
/* Node type descriptor */
static struct ng_type ng_l2tp_typestruct = {
NG_ABI_VERSION,
NG_L2TP_NODE_TYPE,
NULL,
ng_l2tp_constructor,
ng_l2tp_rcvmsg,
ng_l2tp_shutdown,
ng_l2tp_newhook,
NULL,
NULL,
ng_l2tp_rcvdata,
ng_l2tp_disconnect,
ng_l2tp_cmdlist
};
NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct);
/* Sequence number state sanity checking */
#ifdef INVARIANTS
#define L2TP_SEQ_CHECK(seq) ng_l2tp_seq_check(seq)
#else
#define L2TP_SEQ_CHECK(x) do { } while (0)
#endif
/* mem*() macros */
#define memmove(d, s, l) ovbcopy(s, d, l)
#define memset(d, z, l) bzero(d, l) /* XXX */
/* Whether to use m_copypacket() or m_dup() */
#define L2TP_COPY_MBUF m_copypacket
/************************************************************************
NETGRAPH NODE STUFF
************************************************************************/
/*
* Node type constructor
*/
static int
ng_l2tp_constructor(node_p node)
{
priv_p priv;
/* Allocate private structure */
MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
if (priv == NULL)
return (ENOMEM);
NG_NODE_SET_PRIVATE(node, priv);
priv->node = node;
/* Apply a semi-reasonable default configuration */
priv->conf.peer_win = 1;
priv->conf.rexmit_max = L2TP_MAX_REXMIT;
priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
/* Initialize sequence number state */
ng_l2tp_seq_init(priv);
/* Done */
return (0);
}
/*
* Give our OK for a hook to be added.
*/
static int
ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
{
const priv_p priv = NG_NODE_PRIVATE(node);
/* Check hook name */
if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
if (priv->ctrl != NULL)
return (EISCONN);
priv->ctrl = hook;
} else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
if (priv->lower != NULL)
return (EISCONN);
priv->lower = hook;
} else {
static const char hexdig[16] = "0123456789abcdef";
u_int16_t session_id;
hookpriv_p hpriv;
const char *hex;
int i;
int j;
/* Parse hook name to get session ID */
if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
return (EINVAL);
hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
for (session_id = i = 0; i < 4; i++) {
for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
if (j == 16)
return (EINVAL);
session_id = (session_id << 4) | j;
}
if (hex[i] != '\0')
return (EINVAL);
/* Create hook private structure */
MALLOC(hpriv, hookpriv_p,
sizeof(*hpriv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
if (hpriv == NULL)
return (ENOMEM);
hpriv->conf.session_id = htons(session_id);
hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
NG_HOOK_SET_PRIVATE(hook, hpriv);
}
/* Done */
return (0);
}
/*
* Receive a control message.
*/
static int
ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook)
{
const priv_p priv = NG_NODE_PRIVATE(node);
struct ng_mesg *resp = NULL;
struct ng_mesg *msg;
int error = 0;
NGI_GET_MSG(item, msg);
switch (msg->header.typecookie) {
case NGM_L2TP_COOKIE:
switch (msg->header.cmd) {
case NGM_L2TP_SET_CONFIG:
{
struct ng_l2tp_config *const conf =
(struct ng_l2tp_config *)msg->data;
/* Check for invalid or illegal config */
if (msg->header.arglen != sizeof(*conf)) {
error = EINVAL;
break;
}
conf->enabled = !!conf->enabled;
conf->match_id = !!conf->match_id;
conf->tunnel_id = htons(conf->tunnel_id);
conf->peer_id = htons(conf->peer_id);
if (priv->conf.enabled
&& ((priv->conf.tunnel_id != 0
&& conf->tunnel_id != priv->conf.tunnel_id)
|| ((priv->conf.peer_id != 0
&& conf->peer_id != priv->conf.peer_id)))) {
error = EBUSY;
break;
}
/* Save calling node as failure target */
priv->ftarget = NGI_RETADDR(item);
/* Adjust sequence number state */
if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
break;
/* Update node's config */
priv->conf = *conf;
break;
}
case NGM_L2TP_GET_CONFIG:
{
struct ng_l2tp_config *conf;
NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
if (resp == NULL) {
error = ENOMEM;
break;
}
conf = (struct ng_l2tp_config *)resp->data;
*conf = priv->conf;
/* Put ID's in host order */
conf->tunnel_id = ntohs(conf->tunnel_id);
conf->peer_id = ntohs(conf->peer_id);
break;
}
case NGM_L2TP_SET_SESS_CONFIG:
{
struct ng_l2tp_sess_config *const conf =
(struct ng_l2tp_sess_config *)msg->data;
hookpriv_p hpriv;
hook_p hook;
/* Check for invalid or illegal config */
if (msg->header.arglen != sizeof(*conf)) {
error = EINVAL;
break;
}
/* Put ID's in network order */
conf->session_id = htons(conf->session_id);
conf->peer_id = htons(conf->peer_id);
/* Find matching hook */
NG_NODE_FOREACH_HOOK(node, ng_l2tp_find_session,
(void *)(uintptr_t)conf->session_id, hook);
if (hook == NULL) {
error = ENOENT;
break;
}
hpriv = NG_HOOK_PRIVATE(hook);
/* Update hook's config */
hpriv->conf = *conf;
break;
}
case NGM_L2TP_GET_SESS_CONFIG:
{
struct ng_l2tp_sess_config *conf;
u_int16_t session_id;
hookpriv_p hpriv;
hook_p hook;
/* Get session ID */
if (msg->header.arglen != sizeof(session_id)) {
error = EINVAL;
break;
}
memcpy(&session_id, msg->data, 2);
session_id = htons(session_id);
/* Find matching hook */
NG_NODE_FOREACH_HOOK(node, ng_l2tp_find_session,
(void *)(uintptr_t)session_id, hook);
if (hook == NULL) {
error = ENOENT;
break;
}
hpriv = NG_HOOK_PRIVATE(hook);
/* Send response */
NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT);
if (resp == NULL) {
error = ENOMEM;
break;
}
conf = (struct ng_l2tp_sess_config *)resp->data;
*conf = hpriv->conf;
/* Put ID's in host order */
conf->session_id = ntohs(conf->session_id);
conf->peer_id = ntohs(conf->peer_id);
break;
}
case NGM_L2TP_GET_STATS:
case NGM_L2TP_CLR_STATS:
case NGM_L2TP_GETCLR_STATS:
{
if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
NG_MKRESPONSE(resp, msg,
sizeof(priv->stats), M_NOWAIT);
if (resp == NULL) {
error = ENOMEM;
break;
}
memcpy(resp->data,
&priv->stats, sizeof(priv->stats));
}
if (msg->header.cmd != NGM_L2TP_GET_STATS)
memset(&priv->stats, 0, sizeof(priv->stats));
break;
}
default:
error = EINVAL;
break;
}
break;
default:
error = EINVAL;
break;
}
/* Done */
NG_RESPOND_MSG(error, node, item, resp);
NG_FREE_MSG(msg);
return (error);
}
/*
* Receive incoming data on a hook.
*/
static int
ng_l2tp_rcvdata(hook_p hook, item_p item)
{
const node_p node = NG_HOOK_NODE(hook);
const priv_p priv = NG_NODE_PRIVATE(node);
int error;
/* Sanity check */
L2TP_SEQ_CHECK(&priv->seq);
/* If not configured, reject */
if (!priv->conf.enabled) {
NG_FREE_ITEM(item);
return (ENXIO);
}
/* Handle incoming frame from below */
if (hook == priv->lower) {
error = ng_l2tp_recv_lower(node, item);
goto done;
}
/* Handle outgoing control frame */
if (hook == priv->ctrl) {
error = ng_l2tp_recv_ctrl(node, item);
goto done;
}
/* Handle outgoing data frame */
error = ng_l2tp_recv_data(node, item, NG_HOOK_PRIVATE(hook));
done:
/* Done */
L2TP_SEQ_CHECK(&priv->seq);
return (error);
}
/*
* Destroy node
*/
static int
ng_l2tp_shutdown(node_p node)
{
const priv_p priv = NG_NODE_PRIVATE(node);
struct l2tp_seq *const seq = &priv->seq;
/* Sanity check */
L2TP_SEQ_CHECK(seq);
/* Reset sequence number state */
ng_l2tp_seq_reset(priv);
/* Free private data if neither timer is running */
if (!seq->rack_timer_running && !seq->xack_timer_running) {
FREE(priv, M_NETGRAPH_L2TP);
NG_NODE_SET_PRIVATE(node, NULL);
}
/* Unref node */
NG_NODE_UNREF(node);
return (0);
}
/*
* Hook disconnection
*/
static int
ng_l2tp_disconnect(hook_p hook)
{
const node_p node = NG_HOOK_NODE(hook);
const priv_p priv = NG_NODE_PRIVATE(node);
/* Zero out hook pointer */
if (hook == priv->ctrl)
priv->ctrl = NULL;
else if (hook == priv->lower)
priv->lower = NULL;
else {
FREE(NG_HOOK_PRIVATE(hook), M_NETGRAPH_L2TP);
NG_HOOK_SET_PRIVATE(hook, NULL);
}
/* Go away if no longer connected to anything */
if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
ng_rmnode_self(node);
return (0);
}
/*************************************************************************
INTERNAL FUNCTIONS
*************************************************************************/
/*
* Find the hook with a given session ID.
*/
static int
ng_l2tp_find_session(hook_p hook, void *arg)
{
const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
const u_int16_t sid = (u_int16_t)(uintptr_t)arg;
if (hpriv == NULL || hpriv->conf.session_id != sid)
return (-1);
return (0);
}
/*
* Reset a hook's session state.
*/
static int
ng_l2tp_reset_session(hook_p hook, void *arg)
{
const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
if (hpriv != NULL) {
hpriv->conf.control_dseq = 0;
hpriv->conf.enable_dseq = 0;
hpriv->nr = 0;
hpriv->ns = 0;
}
return (-1);
}
/*
* Handle an incoming frame from below.
*/
static int
ng_l2tp_recv_lower(node_p node, item_p item)
{
static const u_int16_t req_bits[2][2] = {
{ L2TP_DATA_0BITS, L2TP_DATA_1BITS },
{ L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
};
const priv_p priv = NG_NODE_PRIVATE(node);
hookpriv_p hpriv = NULL;
hook_p hook = NULL;
u_int16_t ids[2];
struct mbuf *m;
u_int16_t hdr;
u_int16_t ns;
u_int16_t nr;
int is_ctrl;
int error;
int len;
/* Grab mbuf */
NGI_GET_M(item, m);
/* Update stats */
priv->stats.recvPackets++;
priv->stats.recvOctets += m->m_pkthdr.len;
/* Get initial header */
if (m->m_pkthdr.len < 6) {
priv->stats.recvRunts++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
return (EINVAL);
}
if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
return (EINVAL);
}
hdr = ntohs(*mtod(m, u_int16_t *));
m_adj(m, 2);
/* Check required header bits and minimum length */
is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
if ((hdr & req_bits[is_ctrl][0]) != 0
|| (~hdr & req_bits[is_ctrl][1]) != 0) {
priv->stats.recvInvalid++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
return (EINVAL);
}
if (m->m_pkthdr.len < 4 /* tunnel, session id */
+ (2 * ((hdr & L2TP_HDR_LEN) != 0)) /* length field */
+ (4 * ((hdr & L2TP_HDR_SEQ) != 0)) /* seq # fields */
+ (2 * ((hdr & L2TP_HDR_OFF) != 0))) { /* offset field */
priv->stats.recvRunts++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
return (EINVAL);
}
/* Get and validate length field if present */
if ((hdr & L2TP_HDR_LEN) != 0) {
if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
return (EINVAL);
}
len = (u_int16_t)ntohs(*mtod(m, u_int16_t *)) - 4;
m_adj(m, 2);
if (len < 0 || len > m->m_pkthdr.len) {
priv->stats.recvInvalid++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
return (EINVAL);
}
if (len < m->m_pkthdr.len) /* trim extra bytes */
m_adj(m, -(m->m_pkthdr.len - len));
}
/* Get tunnel ID and session ID */
if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
return (EINVAL);
}
memcpy(ids, mtod(m, u_int16_t *), 4);
m_adj(m, 4);
/* Check tunnel ID */
if (ids[0] != priv->conf.tunnel_id
&& (priv->conf.match_id || ids[0] != 0)) {
priv->stats.recvWrongTunnel++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
return (EADDRNOTAVAIL);
}
/* Check session ID (for data packets only) */
if ((hdr & L2TP_HDR_CTRL) == 0) {
NG_NODE_FOREACH_HOOK(node, ng_l2tp_find_session,
(void *)(uintptr_t)ids[1], hook);
if (hook == NULL) {
priv->stats.recvUnknownSID++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
return (ENOTCONN);
}
hpriv = NG_HOOK_PRIVATE(hook);
}
/* Get Ns, Nr fields if present */
if ((hdr & L2TP_HDR_SEQ) != 0) {
if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
return (EINVAL);
}
memcpy(&ns, &mtod(m, u_int16_t *)[0], 2);
ns = ntohs(ns);
memcpy(&nr, &mtod(m, u_int16_t *)[1], 2);
nr = ntohs(nr);
m_adj(m, 4);
}
/* Strip offset padding if present */
if ((hdr & L2TP_HDR_OFF) != 0) {
u_int16_t offset;
/* Get length of offset padding */
if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
return (EINVAL);
}
memcpy(&offset, mtod(m, u_int16_t *), 2);
offset = ntohs(offset);
/* Trim offset padding */
if (offset <= 2 || offset > m->m_pkthdr.len) {
priv->stats.recvInvalid++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
return (EINVAL);
}
m_adj(m, offset);
}
/* Handle control packets */
if ((hdr & L2TP_HDR_CTRL) != 0) {
/* Handle receive ack sequence number Nr */
ng_l2tp_seq_recv_nr(priv, nr);
/* Discard ZLB packets */
if (m->m_pkthdr.len == 0) {
priv->stats.recvZLBs++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
return (0);
}
/*
* Prepend session ID to packet here: we don't want to accept
* the send sequence number Ns if we have to drop the packet
* later because of a memory error, because then the upper
* layer would never get the packet.
*/
M_PREPEND(m, 2, M_DONTWAIT);
if (m == NULL) {
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
return (ENOBUFS);
}
memcpy(mtod(m, u_int16_t *), &ids[1], 2);
/* Now handle send sequence number */
if (ng_l2tp_seq_recv_ns(priv, ns) == -1) {
NG_FREE_ITEM(item);
NG_FREE_M(m);
return (0);
}
/* Deliver packet to upper layers */
NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
return (error);
}
/* Follow peer's lead in data sequencing, if configured to do so */
if (!hpriv->conf.control_dseq)
hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
/* Handle data sequence numbers if present and enabled */
if ((hdr & L2TP_HDR_SEQ) != 0) {
if (hpriv->conf.enable_dseq
&& L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
NG_FREE_ITEM(item); /* duplicate or out of order */
NG_FREE_M(m);
priv->stats.recvDataDrops++;
return (0);
}
hpriv->nr = ns + 1;
}
/* Drop empty data packets */
if (m->m_pkthdr.len == 0) {
NG_FREE_ITEM(item);
NG_FREE_M(m);
return (0);
}
/* Deliver data */
NG_FWD_NEW_DATA(error, item, hook, m);
return (error);
}
/*
* Handle an outgoing control frame.
*/
static int
ng_l2tp_recv_ctrl(node_p node, item_p item)
{
const priv_p priv = NG_NODE_PRIVATE(node);
struct l2tp_seq *const seq = &priv->seq;
struct mbuf *m;
int i;
/* Grab mbuf and discard other stuff XXX */
NGI_GET_M(item, m);
NG_FREE_ITEM(item);
/* Packet should have session ID prepended */
if (m->m_pkthdr.len < 2) {
priv->stats.xmitInvalid++;
m_freem(m);
return (EINVAL);
}
/* Check max length */
if (m->m_pkthdr.len >= 0x10000 - 14) {
priv->stats.xmitTooBig++;
m_freem(m);
return (EOVERFLOW);
}
/* Find next empty slot in transmit queue */
for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
if (i == L2TP_MAX_XWIN) {
priv->stats.xmitDrops++;
m_freem(m);
return (ENOBUFS);
}
seq->xwin[i] = m;
/* Sanity check receive ack timer state */
KASSERT((i == 0) ^ seq->rack_timer_running,
("%s: xwin %d full but rack timer %srunning",
__FUNCTION__, i, seq->rack_timer_running ? "" : "not "));
/* If peer's receive window is already full, nothing else to do */
if (i >= seq->cwnd)
return (0);
/* Start retransmit timer if not already running */
if (!seq->rack_timer_running) {
callout_reset(&seq->rack_timer,
hz, ng_l2tp_seq_rack_timeout, node);
seq->rack_timer_running = 1;
NG_NODE_REF(node);
}
/* Copy packet */
if ((m = L2TP_COPY_MBUF(seq->xwin[i], M_NOWAIT)) == NULL) {
priv->stats.memoryFailures++;
return (ENOBUFS);
}
/* Send packet and increment xmit sequence number */
return (ng_l2tp_xmit_ctrl(priv, m, seq->ns++));
}
/*
* Handle an outgoing data frame.
*/
static int
ng_l2tp_recv_data(node_p node, item_p item, hookpriv_p hpriv)
{
const priv_p priv = NG_NODE_PRIVATE(node);
struct mbuf *m;
u_int16_t hdr;
int error;
int i = 1;
/* Get mbuf */
NGI_GET_M(item, m);
/* Check max length */
if (m->m_pkthdr.len >= 0x10000 - 12) {
priv->stats.xmitDataTooBig++;
NG_FREE_ITEM(item);
NG_FREE_M(m);
return (EOVERFLOW);
}
/* Prepend L2TP header */
M_PREPEND(m, 6
+ (2 * (hpriv->conf.include_length != 0))
+ (4 * (hpriv->conf.enable_dseq != 0)),
M_DONTWAIT);
if (m == NULL) {
priv->stats.memoryFailures++;
NG_FREE_ITEM(item);
return (ENOBUFS);
}
hdr = L2TP_DATA_HDR;
if (hpriv->conf.include_length) {
hdr |= L2TP_HDR_LEN;
mtod(m, u_int16_t *)[i++] = htons(m->m_pkthdr.len);
}
mtod(m, u_int16_t *)[i++] = priv->conf.peer_id;
mtod(m, u_int16_t *)[i++] = hpriv->conf.peer_id;
if (hpriv->conf.enable_dseq) {
hdr |= L2TP_HDR_SEQ;
mtod(m, u_int16_t *)[i++] = htons(hpriv->ns);
mtod(m, u_int16_t *)[i++] = htons(hpriv->nr);
hpriv->ns++;
}
mtod(m, u_int16_t *)[0] = htons(hdr);
/* Send packet */
NG_FWD_NEW_DATA(error, item, priv->lower, m);
return (error);
}
/*
* Send a message to our controlling node that we've failed.
*/
static void
ng_l2tp_seq_failure(priv_p priv)
{
struct ng_mesg *msg;
int error;
NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT);
if (msg == NULL)
return;
NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
}
/************************************************************************
SEQUENCE NUMBER HANDLING
************************************************************************/
/*
* Initialize sequence number state.
*/
static void
ng_l2tp_seq_init(priv_p priv)
{
struct l2tp_seq *const seq = &priv->seq;
KASSERT(priv->conf.peer_win >= 1,
("%s: peer_win is zero", __FUNCTION__));
memset(seq, 0, sizeof(*seq));
seq->cwnd = 1;
seq->wmax = priv->conf.peer_win;
if (seq->wmax > L2TP_MAX_XWIN)
seq->wmax = L2TP_MAX_XWIN;
seq->ssth = seq->wmax;
seq->max_rexmits = priv->conf.rexmit_max;
seq->max_rexmit_to = priv->conf.rexmit_max_to;
callout_init(&seq->rack_timer, 0);
callout_init(&seq->xack_timer, 0);
L2TP_SEQ_CHECK(seq);
}
/*
* Adjust sequence number state accordingly after reconfiguration.
*/
static int
ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
{
struct l2tp_seq *const seq = &priv->seq;
u_int16_t new_wmax;
/* If disabling node, reset state sequence number */
if (!conf->enabled) {
ng_l2tp_seq_reset(priv);
return (0);
}
/* Adjust peer's max recv window; it can only increase */
new_wmax = conf->peer_win;
if (new_wmax > L2TP_MAX_XWIN)
new_wmax = L2TP_MAX_XWIN;
if (new_wmax == 0)
return (EINVAL);
if (new_wmax < seq->wmax)
return (EBUSY);
seq->wmax = new_wmax;
/* Update retransmit parameters */
seq->max_rexmits = conf->rexmit_max;
seq->max_rexmit_to = conf->rexmit_max_to;
/* Done */
return (0);
}
/*
* Reset sequence number state.
*/
static void
ng_l2tp_seq_reset(priv_p priv)
{
struct l2tp_seq *const seq = &priv->seq;
hook_p hook;
int i;
/* Sanity check */
L2TP_SEQ_CHECK(seq);
/* Stop timers */
if (seq->rack_timer_running && callout_stop(&seq->rack_timer) == 1) {
seq->rack_timer_running = 0;
NG_NODE_UNREF(priv->node);
}
if (seq->xack_timer_running && callout_stop(&seq->xack_timer) == 1) {
seq->xack_timer_running = 0;
NG_NODE_UNREF(priv->node);
}
/* Free retransmit queue */
for (i = 0; i < L2TP_MAX_XWIN; i++) {
if (seq->xwin[i] == NULL)
break;
m_freem(seq->xwin[i]);
}
/* Reset session hooks' sequence number states */
NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook);
/* Reset node's sequence number state */
memset(seq, 0, sizeof(*seq));
seq->cwnd = 1;
seq->wmax = L2TP_MAX_XWIN;
seq->ssth = seq->wmax;
/* Done */
L2TP_SEQ_CHECK(seq);
}
/*
* Handle receipt of an acknowledgement value (Nr) from peer.
*/
static void
ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
{
struct l2tp_seq *const seq = &priv->seq;
struct mbuf *m;
int nack;
int i;
/* Verify peer's ACK is in range */
if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0)
return; /* duplicate ack */
if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
priv->stats.recvBadAcks++; /* ack for packet not sent */
return;
}
KASSERT(nack <= L2TP_MAX_XWIN,
("%s: nack=%d > %d", __FUNCTION__, nack, L2TP_MAX_XWIN));
/* Update receive ack stats */
seq->rack = nr;
seq->rexmits = 0;
/* Free acknowledged packets and shift up packets in the xmit queue */
for (i = 0; i < nack; i++)
m_freem(seq->xwin[i]);
memmove(seq->xwin, seq->xwin + nack,
(L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
nack * sizeof(*seq->xwin));
/*
* Do slow-start/congestion avoidance windowing algorithm described
* in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
* ACK had arrived separately.
*/
if (seq->cwnd < seq->wmax) {
/* Handle slow start phase */
if (seq->cwnd < seq->ssth) {
seq->cwnd += nack;
nack = 0;
if (seq->cwnd > seq->ssth) { /* into cg.av. phase */
nack = seq->cwnd - seq->ssth;
seq->cwnd = seq->ssth;
}
}
/* Handle congestion avoidance phase */
if (seq->cwnd >= seq->ssth) {
seq->acks += nack;
while (seq->acks >= seq->cwnd) {
seq->acks -= seq->cwnd;
if (seq->cwnd < seq->wmax)
seq->cwnd++;
}
}
}
/* Stop xmit timer */
if (seq->rack_timer_running && callout_stop(&seq->rack_timer) == 1) {
seq->rack_timer_running = 0;
NG_NODE_UNREF(priv->node);
}
/* If transmit queue is empty, we're done for now */
if (seq->xwin[0] == NULL)
return;
/* Start restransmit timer again */
callout_reset(&seq->rack_timer,
hz, ng_l2tp_seq_rack_timeout, priv->node);
seq->rack_timer_running = 1;
NG_NODE_REF(priv->node);
/*
* Send more packets, trying to keep peer's receive window full.
* If there is a memory error, pretend packet was sent, as it
* will get retransmitted later anyway.
*/
while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
&& seq->xwin[i] != NULL) {
if ((m = L2TP_COPY_MBUF(seq->xwin[i], M_NOWAIT)) == NULL)
priv->stats.memoryFailures++;
else
ng_l2tp_xmit_ctrl(priv, m, seq->ns);
seq->ns++;
}
}
/*
* Handle receipt of a sequence number value (Ns) from peer.
* We make no attempt to re-order out of order packets.
*
* This function should only be called for non-ZLB packets.
*
* Returns:
* 0 Accept packet
* -1 Drop packet
*/
static int
ng_l2tp_seq_recv_ns(priv_p priv, u_int16_t ns)
{
struct l2tp_seq *const seq = &priv->seq;
/* If not what we expect, drop packet and send an immediate ZLB ack */
if (ns != seq->nr) {
if (L2TP_SEQ_DIFF(ns, seq->nr) < 0)
priv->stats.recvDuplicates++;
else
priv->stats.recvOutOfOrder++;
ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
return (-1);
}
/* Update recv sequence number */
seq->nr++;
/* Start receive ack timer, if not already running */
if (!seq->xack_timer_running) {
callout_reset(&seq->xack_timer,
L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout, priv->node);
seq->xack_timer_running = 1;
NG_NODE_REF(priv->node);
}
/* Accept packet */
return (0);
}
/*
* Handle an ack timeout. We have an outstanding ack that we
* were hoping to piggy-back, but haven't, so send a ZLB.
*/
static void
ng_l2tp_seq_xack_timeout(void *arg)
{
const node_p node = arg;
const priv_p priv = NG_NODE_PRIVATE(node);
struct l2tp_seq *const seq = &priv->seq;
int s;
/* Check if node is going away */
s = splnet();
if (NG_NODE_NOT_VALID(node)) {
seq->xack_timer_running = 0;
if (!seq->rack_timer_running) {
FREE(priv, M_NETGRAPH_L2TP);
NG_NODE_SET_PRIVATE(node, NULL);
}
NG_NODE_UNREF(node);
splx(s);
return;
}
/* Sanity check */
L2TP_SEQ_CHECK(seq);
/* If ack is still outstanding, send a ZLB */
if (seq->xack != seq->nr)
ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
/* Done */
seq->xack_timer_running = 0;
NG_NODE_UNREF(node);
L2TP_SEQ_CHECK(seq);
splx(s);
}
/*
* Handle a transmit timeout. The peer has failed to respond
* with an ack for our packet, so retransmit it.
*/
static void
ng_l2tp_seq_rack_timeout(void *arg)
{
const node_p node = arg;
const priv_p priv = NG_NODE_PRIVATE(node);
struct l2tp_seq *const seq = &priv->seq;
struct mbuf *m;
u_int delay;
int s;
/* Check if node is going away */
s = splnet();
if (NG_NODE_NOT_VALID(node)) {
seq->rack_timer_running = 0;
if (!seq->xack_timer_running) {
FREE(priv, M_NETGRAPH_L2TP);
NG_NODE_SET_PRIVATE(node, NULL);
}
NG_NODE_UNREF(node);
splx(s);
return;
}
/* Sanity check */
L2TP_SEQ_CHECK(seq);
/* Make sure peer's ack is still outstanding before doing anything */
if (seq->rack == seq->ns) {
seq->rack_timer_running = 0;
NG_NODE_UNREF(node);
goto done;
}
priv->stats.xmitRetransmits++;
/* Have we reached the retransmit limit? If so, notify owner. */
if (seq->rexmits++ >= seq->max_rexmits)
ng_l2tp_seq_failure(priv);
/* Restart timer, this time with an increased delay */
delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
if (delay > seq->max_rexmit_to)
delay = seq->max_rexmit_to;
callout_reset(&seq->rack_timer,
hz * delay, ng_l2tp_seq_rack_timeout, node);
/* Do slow-start/congestion algorithm windowing algorithm */
seq->ssth = (seq->cwnd + 1) / 2;
seq->cwnd = 1;
seq->acks = 0;
/* Retransmit oldest unack'd packet */
if ((m = L2TP_COPY_MBUF(seq->xwin[0], M_NOWAIT)) == NULL)
priv->stats.memoryFailures++;
else
ng_l2tp_xmit_ctrl(priv, m, seq->rack);
done:
/* Done */
L2TP_SEQ_CHECK(seq);
splx(s);
}
/*
* Transmit a control stream packet, payload optional.
* The transmit sequence number is not incremented.
*/
static int
ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
{
struct l2tp_seq *const seq = &priv->seq;
u_int16_t session_id = 0;
meta_p meta = NULL;
int error;
/* If no mbuf passed, send an empty packet (ZLB) */
if (m == NULL) {
/* Create a new mbuf for ZLB packet */
MGETHDR(m, M_DONTWAIT, MT_DATA);
if (m == NULL) {
priv->stats.memoryFailures++;
return (ENOBUFS);
}
m->m_len = m->m_pkthdr.len = 12;
m->m_pkthdr.rcvif = NULL;
priv->stats.xmitZLBs++;
} else {
/* Strip off session ID */
if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
priv->stats.memoryFailures++;
return (ENOBUFS);
}
memcpy(&session_id, mtod(m, u_int16_t *), 2);
m_adj(m, 2);
/* Make room for L2TP header */
M_PREPEND(m, 12, M_DONTWAIT);
if (m == NULL) {
priv->stats.memoryFailures++;
return (ENOBUFS);
}
}
/* Fill in L2TP header */
mtod(m, u_int16_t *)[0] = htons(L2TP_CTRL_HDR);
mtod(m, u_int16_t *)[1] = htons(m->m_pkthdr.len);
mtod(m, u_int16_t *)[2] = priv->conf.peer_id;
mtod(m, u_int16_t *)[3] = session_id;
mtod(m, u_int16_t *)[4] = htons(ns);
mtod(m, u_int16_t *)[5] = htons(seq->nr);
/* Update sequence number info and stats */
priv->stats.xmitPackets++;
priv->stats.xmitOctets += m->m_pkthdr.len;
/* Stop ack timer: we're sending an ack with this packet */
if (seq->xack_timer_running && callout_stop(&seq->xack_timer) == 1) {
seq->xack_timer_running = 0;
NG_NODE_UNREF(priv->node);
}
seq->xack = seq->nr;
/* Send packet */
NG_SEND_DATA(error, priv->lower, m, meta);
return (error);
}
#ifdef INVARIANTS
/*
* Sanity check sequence number state.
*/
static void
ng_l2tp_seq_check(struct l2tp_seq *seq)
{
const int self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
const int peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
int i;
#define CHECK(p) KASSERT((p), ("%s: not: %s", __FUNCTION__, #p))
CHECK(seq->wmax <= L2TP_MAX_XWIN);
CHECK(seq->cwnd >= 1);
CHECK(seq->cwnd <= seq->wmax);
CHECK(seq->ssth >= 1);
CHECK(seq->ssth <= seq->wmax);
if (seq->cwnd < seq->ssth)
CHECK(seq->acks == 0);
else
CHECK(seq->acks <= seq->cwnd);
CHECK(self_unack >= 0);
CHECK(peer_unack >= 0);
CHECK(peer_unack <= seq->wmax);
CHECK((self_unack == 0) ^ seq->xack_timer_running);
CHECK((peer_unack == 0) ^ seq->rack_timer_running);
CHECK(seq->rack_timer_running || !callout_pending(&seq->rack_timer));
CHECK(seq->xack_timer_running || !callout_pending(&seq->xack_timer));
for (i = 0; i < peer_unack; i++)
CHECK(seq->xwin[i] != NULL);
for ( ; i < seq->cwnd; i++) /* verify peer's recv window full */
CHECK(seq->xwin[i] == NULL);
#undef CHECK
}
#endif /* INVARIANTS */
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