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81204c492b
linux/net/tipc/link.h
Jon Paul Maloy 81204c492b tipc: improve sequence number checking 
The sequence number of an incoming packet is currently only checked
for less than, equality to, or bigger than the next expected number,
meaning that the receive window in practice becomes one half sequence
number cycle, or U16_MAX/2. This does not make sense, and may not even
be safe if there are extreme delays in the network. Any packet sent by
the peer during the ongoing cycle must belong inside his current send
window, or should otherwise be dropped if possible.

Since a link endpoint cannot know its peer's current send window, it
has to base this sanity check on a worst-case assumption, i.e., that
the peer is using a maximum sized window of 8191 packets. Using this
assumption, we now add a check that the sequence number is not bigger
than next_expected + TIPC_MAX_LINK_WIN. We also re-order the checks
done, so that the receive window test is performed before the gap test.
This way, we are guaranteed that no packet with illegal sequence numbers
are ever added to the deferred queue.

Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-10-15 23:55:20 -07:00

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/*
* net/tipc/link.h: Include file for TIPC link code
*
* Copyright (c) 1995-2006, 2013-2014, Ericsson AB
* Copyright (c) 2004-2005, 2010-2011, Wind River Systems
* 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.
* 3. Neither the names of the copyright holders nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* Alternatively, this software may be distributed under the terms of the
* GNU General Public License ("GPL") version 2 as published by the Free
* Software Foundation.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
*/
#ifndef _TIPC_LINK_H
#define _TIPC_LINK_H
#include <net/genetlink.h>
#include "msg.h"
#include "node.h"
/* TIPC-specific error codes
*/
#define ELINKCONG EAGAIN /* link congestion <=> resource unavailable */
/* Out-of-range value for link sequence numbers
*/
#define INVALID_LINK_SEQ 0x10000
/* Link FSM events:
*/
enum {
LINK_ESTABLISH_EVT = 0xec1ab1e,
LINK_PEER_RESET_EVT = 0x9eed0e,
LINK_FAILURE_EVT = 0xfa110e,
LINK_RESET_EVT = 0x10ca1d0e,
LINK_FAILOVER_BEGIN_EVT = 0xfa110bee,
LINK_FAILOVER_END_EVT = 0xfa110ede,
LINK_SYNCH_BEGIN_EVT = 0xc1ccbee,
LINK_SYNCH_END_EVT = 0xc1ccede
};
/* Events returned from link at packet reception or at timeout
*/
enum {
TIPC_LINK_UP_EVT = 1,
TIPC_LINK_DOWN_EVT = (1 << 1)
};
/* Starting value for maximum packet size negotiation on unicast links
* (unless bearer MTU is less)
*/
#define MAX_PKT_DEFAULT 1500
struct tipc_stats {
u32 sent_info; /* used in counting # sent packets */
u32 recv_info; /* used in counting # recv'd packets */
u32 sent_states;
u32 recv_states;
u32 sent_probes;
u32 recv_probes;
u32 sent_nacks;
u32 recv_nacks;
u32 sent_acks;
u32 sent_bundled;
u32 sent_bundles;
u32 recv_bundled;
u32 recv_bundles;
u32 retransmitted;
u32 sent_fragmented;
u32 sent_fragments;
u32 recv_fragmented;
u32 recv_fragments;
u32 link_congs; /* # port sends blocked by congestion */
u32 deferred_recv;
u32 duplicates;
u32 max_queue_sz; /* send queue size high water mark */
u32 accu_queue_sz; /* used for send queue size profiling */
u32 queue_sz_counts; /* used for send queue size profiling */
u32 msg_length_counts; /* used for message length profiling */
u32 msg_lengths_total; /* used for message length profiling */
u32 msg_length_profile[7]; /* used for msg. length profiling */
};
/**
* struct tipc_link - TIPC link data structure
* @addr: network address of link's peer node
* @name: link name character string
* @media_addr: media address to use when sending messages over link
* @timer: link timer
* @owner: pointer to peer node
* @refcnt: reference counter for permanent references (owner node & timer)
* @peer_session: link session # being used by peer end of link
* @peer_bearer_id: bearer id used by link's peer endpoint
* @bearer_id: local bearer id used by link
* @tolerance: minimum link continuity loss needed to reset link [in ms]
* @keepalive_intv: link keepalive timer interval
* @abort_limit: # of unacknowledged continuity probes needed to reset link
* @state: current state of link FSM
* @silent_intv_cnt: # of timer intervals without any reception from peer
* @proto_msg: template for control messages generated by link
* @pmsg: convenience pointer to "proto_msg" field
* @priority: current link priority
* @net_plane: current link network plane ('A' through 'H')
* @backlog_limit: backlog queue congestion thresholds (indexed by importance)
* @exp_msg_count: # of tunnelled messages expected during link changeover
* @reset_rcv_checkpt: seq # of last acknowledged message at time of link reset
* @mtu: current maximum packet size for this link
* @advertised_mtu: advertised own mtu when link is being established
* @transmitq: queue for sent, non-acked messages
* @backlogq: queue for messages waiting to be sent
* @snt_nxt: next sequence number to use for outbound messages
* @last_retransmitted: sequence number of most recently retransmitted message
* @stale_count: # of identical retransmit requests made by peer
* @rcv_nxt: next sequence number to expect for inbound messages
* @deferred_queue: deferred queue saved OOS b'cast message received from node
* @unacked_window: # of inbound messages rx'd without ack'ing back to peer
* @inputq: buffer queue for messages to be delivered upwards
* @namedq: buffer queue for name table messages to be delivered upwards
* @next_out: ptr to first unsent outbound message in queue
* @wakeupq: linked list of wakeup msgs waiting for link congestion to abate
* @long_msg_seq_no: next identifier to use for outbound fragmented messages
* @reasm_buf: head of partially reassembled inbound message fragments
* @stats: collects statistics regarding link activity
*/
struct tipc_link {
u32 addr;
char name[TIPC_MAX_LINK_NAME];
struct tipc_media_addr *media_addr;
struct tipc_node *owner;
/* Management and link supervision data */
u32 peer_session;
u32 peer_bearer_id;
u32 bearer_id;
u32 tolerance;
unsigned long keepalive_intv;
u32 abort_limit;
u32 state;
u32 silent_intv_cnt;
struct {
unchar hdr[INT_H_SIZE];
unchar body[TIPC_MAX_IF_NAME];
} proto_msg;
struct tipc_msg *pmsg;
u32 priority;
char net_plane;
/* Failover/synch */
u16 drop_point;
struct sk_buff *failover_reasm_skb;
/* Max packet negotiation */
u16 mtu;
u16 advertised_mtu;
/* Sending */
struct sk_buff_head transmq;
struct sk_buff_head backlogq;
struct {
u16 len;
u16 limit;
} backlog[5];
u16 snd_nxt;
u16 last_retransm;
u16 window;
u32 stale_count;
/* Reception */
u16 rcv_nxt;
u32 rcv_unacked;
struct sk_buff_head deferdq;
struct sk_buff_head *inputq;
struct sk_buff_head *namedq;
/* Congestion handling */
struct sk_buff_head wakeupq;
/* Fragmentation/reassembly */
struct sk_buff *reasm_buf;
/* Statistics */
struct tipc_stats stats;
};
bool tipc_link_create(struct tipc_node *n, struct tipc_bearer *b, u32 session,
u32 ownnode, u32 peer, struct tipc_media_addr *maddr,
struct sk_buff_head *inputq, struct sk_buff_head *namedq,
struct tipc_link **link);
void tipc_link_tnl_prepare(struct tipc_link *l, struct tipc_link *tnl,
int mtyp, struct sk_buff_head *xmitq);
void tipc_link_build_bcast_sync_msg(struct tipc_link *l,
struct sk_buff_head *xmitq);
int tipc_link_fsm_evt(struct tipc_link *l, int evt);
void tipc_link_reset_fragments(struct tipc_link *l_ptr);
bool tipc_link_is_up(struct tipc_link *l);
bool tipc_link_is_reset(struct tipc_link *l);
bool tipc_link_is_synching(struct tipc_link *l);
bool tipc_link_is_failingover(struct tipc_link *l);
bool tipc_link_is_blocked(struct tipc_link *l);
int tipc_link_is_active(struct tipc_link *l_ptr);
void tipc_link_purge_queues(struct tipc_link *l_ptr);
void tipc_link_purge_backlog(struct tipc_link *l);
void tipc_link_reset(struct tipc_link *l_ptr);
int __tipc_link_xmit(struct net *net, struct tipc_link *link,
struct sk_buff_head *list);
int tipc_link_xmit(struct tipc_link *link, struct sk_buff_head *list,
struct sk_buff_head *xmitq);
void tipc_link_proto_xmit(struct tipc_link *l_ptr, u32 msg_typ, int prob,
u32 gap, u32 tolerance, u32 priority);
void tipc_link_push_packets(struct tipc_link *l_ptr);
u32 tipc_link_defer_pkt(struct sk_buff_head *list, struct sk_buff *buf);
void tipc_link_set_queue_limits(struct tipc_link *l_ptr, u32 window);
void tipc_link_retransmit(struct tipc_link *l_ptr,
struct sk_buff *start, u32 retransmits);
struct sk_buff *tipc_skb_queue_next(const struct sk_buff_head *list,
const struct sk_buff *skb);
int tipc_nl_link_dump(struct sk_buff *skb, struct netlink_callback *cb);
int tipc_nl_link_get(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_link_set(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_link_reset_stats(struct sk_buff *skb, struct genl_info *info);
int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[]);
int tipc_link_timeout(struct tipc_link *l, struct sk_buff_head *xmitq);
int tipc_link_rcv(struct tipc_link *l, struct sk_buff *skb,
struct sk_buff_head *xmitq);
#endif
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