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/*-
* Copyright (c) 2008
* Swinburne University of Technology, Melbourne, Australia.
*
* 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 AUTHORS 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 AUTHORS 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.
*/
/*
* Alias_sctp forms part of the libalias kernel module to handle
* Network Address Translation (NAT) for the SCTP protocol.
*
* This software was developed by David A. Hayes and Jason But
*
* The design is outlined in CAIA technical report number 080618A
* (D. Hayes and J. But, "Alias_sctp Version 0.1: SCTP NAT implementation in IPFW")
*
* Development is part of the CAIA SONATA project,
* proposed by Jason But and Grenville Armitage:
* http://caia.swin.edu.au/urp/sonata/
*
*
* This project has been made possible in part by a grant from
* the Cisco University Research Program Fund at Community
* Foundation Silicon Valley.
*
*/
/** @mainpage
* Alias_sctp is part of the SONATA (http://caia.swin.edu.au/urp/sonata) project
* to develop and release a BSD licensed implementation of a Network Address
* Translation (NAT) module that supports the Stream Control Transmission
* Protocol (SCTP).
*
* Traditional address and port number look ups are inadequate for SCTP's
* operation due to both processing requirements and issues with multi-homing.
* Alias_sctp integrates with FreeBSD's ipfw/libalias NAT system.
*
* Version 0.2 features include:
* - Support for global multi-homing
* - Support for ASCONF modification from Internet Draft
* (draft-stewart-behave-sctpnat-04, R. Stewart and M. Tuexen, "Stream control
* transmission protocol (SCTP) network address translation," Jul. 2008) to
* provide support for multi-homed privately addressed hosts
* - Support for forwarding of T-flagged packets
* - Generation and delivery of AbortM/ErrorM packets upon detection of NAT
* collisions
* - Per-port forwarding rules
* - Dynamically controllable logging and statistics
* - Dynamic management of timers
* - Dynamic control of hash-table size
*/
/* $FreeBSD: release/9.1.0/sys/netinet/libalias/alias_sctp.c 218909 2011-02-21 09:01:34Z brucec $ */
#ifdef _KERNEL
#include <machine/stdarg.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/syslog.h>
#include <netinet/libalias/alias_sctp.h>
#include <netinet/libalias/alias.h>
#include <netinet/libalias/alias_local.h>
#include <netinet/sctp_crc32.h>
#include <machine/in_cksum.h>
#else
#include "alias_sctp.h"
#include <arpa/inet.h>
#include "alias.h"
#include "alias_local.h"
#include <machine/in_cksum.h>
#include <sys/libkern.h>
#endif //#ifdef _KERNEL
/* ----------------------------------------------------------------------
* FUNCTION PROTOTYPES
* ----------------------------------------------------------------------
*/
/* Packet Parsing Functions */
static int sctp_PktParser(struct libalias *la, int direction, struct ip *pip,
struct sctp_nat_msg *sm, struct sctp_nat_assoc **passoc);
static int GetAsconfVtags(struct libalias *la, struct sctp_nat_msg *sm,
uint32_t *l_vtag, uint32_t *g_vtag, int direction);
static int IsASCONFack(struct libalias *la, struct sctp_nat_msg *sm, int direction);
static void AddGlobalIPAddresses(struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc, int direction);
static int Add_Global_Address_to_List(struct sctp_nat_assoc *assoc, struct sctp_GlobalAddress *G_addr);
static void RmGlobalIPAddresses(struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc, int direction);
static int IsADDorDEL(struct libalias *la, struct sctp_nat_msg *sm, int direction);
/* State Machine Functions */
static int ProcessSctpMsg(struct libalias *la, int direction, \
struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc);
static int ID_process(struct libalias *la, int direction,\
struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm);
static int INi_process(struct libalias *la, int direction,\
struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm);
static int INa_process(struct libalias *la, int direction,\
struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm);
static int UP_process(struct libalias *la, int direction,\
struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm);
static int CL_process(struct libalias *la, int direction,\
struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm);
static void TxAbortErrorM(struct libalias *la, struct sctp_nat_msg *sm,\
struct sctp_nat_assoc *assoc, int sndrply, int direction);
/* Hash Table Functions */
static struct sctp_nat_assoc*
FindSctpLocal(struct libalias *la, struct in_addr l_addr, struct in_addr g_addr, uint32_t l_vtag, uint16_t l_port, uint16_t g_port);
static struct sctp_nat_assoc*
FindSctpGlobal(struct libalias *la, struct in_addr g_addr, uint32_t g_vtag, uint16_t g_port, uint16_t l_port, int *partial_match);
static struct sctp_nat_assoc*
FindSctpGlobalClash(struct libalias *la, struct sctp_nat_assoc *Cassoc);
static struct sctp_nat_assoc*
FindSctpLocalT(struct libalias *la, struct in_addr g_addr, uint32_t l_vtag, uint16_t g_port, uint16_t l_port);
static struct sctp_nat_assoc*
FindSctpGlobalT(struct libalias *la, struct in_addr g_addr, uint32_t g_vtag, uint16_t l_port, uint16_t g_port);
static int AddSctpAssocLocal(struct libalias *la, struct sctp_nat_assoc *assoc, struct in_addr g_addr);
static int AddSctpAssocGlobal(struct libalias *la, struct sctp_nat_assoc *assoc);
static void RmSctpAssoc(struct libalias *la, struct sctp_nat_assoc *assoc);
static void freeGlobalAddressList(struct sctp_nat_assoc *assoc);
/* Timer Queue Functions */
static void sctp_AddTimeOut(struct libalias *la, struct sctp_nat_assoc *assoc);
static void sctp_RmTimeOut(struct libalias *la, struct sctp_nat_assoc *assoc);
static void sctp_ResetTimeOut(struct libalias *la, struct sctp_nat_assoc *assoc, int newexp);
void sctp_CheckTimers(struct libalias *la);
/* Logging Functions */
static void logsctperror(char* errormsg, uint32_t vtag, int error, int direction);
static void logsctpparse(int direction, struct sctp_nat_msg *sm);
static void logsctpassoc(struct sctp_nat_assoc *assoc, char *s);
static void logTimerQ(struct libalias *la);
static void logSctpGlobal(struct libalias *la);
static void logSctpLocal(struct libalias *la);
#ifdef _KERNEL
static void SctpAliasLog(const char *format, ...);
#endif
/** @defgroup external External code changes and modifications
*
* Some changes have been made to files external to alias_sctp.(c|h). These
* changes are primarily due to code needing to call static functions within
* those files or to perform extra functionality that can only be performed
* within these files.
*/
/** @ingroup external
* @brief Log current statistics for the libalias instance
*
* This function is defined in alias_db.c, since it calls static functions in
* this file
*
* Calls the higher level ShowAliasStats() in alias_db.c which logs all current
* statistics about the libalias instance - including SCTP statistics
*
* @param la Pointer to the libalias instance
*/
void SctpShowAliasStats(struct libalias *la);
#ifdef _KERNEL
MALLOC_DEFINE(M_SCTPNAT, "sctpnat", "sctp nat dbs");
/* Use kernel allocator. */
#ifdef _SYS_MALLOC_H_
#define sn_malloc(x) malloc(x, M_SCTPNAT, M_NOWAIT|M_ZERO)
#define sn_calloc(n,x) sn_malloc(x * n)
#define sn_free(x) free(x, M_SCTPNAT)
#endif// #ifdef _SYS_MALLOC_H_
#else //#ifdef _KERNEL
#define sn_malloc(x) malloc(x)
#define sn_calloc(n, x) calloc(n, x)
#define sn_free(x) free(x)
#endif //#ifdef _KERNEL
/** @defgroup packet_parser SCTP Packet Parsing
*
* Macros to:
* - Return pointers to the first and next SCTP chunks within an SCTP Packet
* - Define possible return values of the packet parsing process
* - SCTP message types for storing in the sctp_nat_msg structure @{
*/
#define SN_SCTP_FIRSTCHUNK(sctphead) (struct sctp_chunkhdr *)(((char *)sctphead) + sizeof(struct sctphdr))
/**< Returns a pointer to the first chunk in an SCTP packet given a pointer to the SCTP header */
#define SN_SCTP_NEXTCHUNK(chunkhead) (struct sctp_chunkhdr *)(((char *)chunkhead) + SCTP_SIZE32(ntohs(chunkhead->chunk_length)))
/**< Returns a pointer to the next chunk in an SCTP packet given a pointer to the current chunk */
#define SN_SCTP_NEXTPARAM(param) (struct sctp_paramhdr *)(((char *)param) + SCTP_SIZE32(ntohs(param->param_length)))
/**< Returns a pointer to the next parameter in an SCTP packet given a pointer to the current parameter */
#define SN_MIN_CHUNK_SIZE 4 /**< Smallest possible SCTP chunk size in bytes */
#define SN_MIN_PARAM_SIZE 4 /**< Smallest possible SCTP param size in bytes */
#define SN_VTAG_PARAM_SIZE 12 /**< Size of SCTP ASCONF vtag param in bytes */
#define SN_ASCONFACK_PARAM_SIZE 8 /**< Size of SCTP ASCONF ACK param in bytes */
/* Packet parsing return codes */
#define SN_PARSE_OK 0 /**< Packet parsed for SCTP messages */
#define SN_PARSE_ERROR_IPSHL 1 /**< Packet parsing error - IP and SCTP common header len */
#define SN_PARSE_ERROR_AS_MALLOC 2 /**< Packet parsing error - assoc malloc */
#define SN_PARSE_ERROR_CHHL 3 /**< Packet parsing error - Chunk header len */
#define SN_PARSE_ERROR_DIR 4 /**< Packet parsing error - Direction */
#define SN_PARSE_ERROR_VTAG 5 /**< Packet parsing error - Vtag */
#define SN_PARSE_ERROR_CHUNK 6 /**< Packet parsing error - Chunk */
#define SN_PARSE_ERROR_PORT 7 /**< Packet parsing error - Port=0 */
#define SN_PARSE_ERROR_LOOKUP 8 /**< Packet parsing error - Lookup */
#define SN_PARSE_ERROR_PARTIALLOOKUP 9 /**< Packet parsing error - partial lookup only found */
#define SN_PARSE_ERROR_LOOKUP_ABORT 10 /**< Packet parsing error - Lookup - but abort packet */
/* Alias_sctp performs its processing based on a number of key messages */
#define SN_SCTP_ABORT 0x0000 /**< a packet containing an ABORT chunk */
#define SN_SCTP_INIT 0x0001 /**< a packet containing an INIT chunk */
#define SN_SCTP_INITACK 0x0002 /**< a packet containing an INIT-ACK chunk */
#define SN_SCTP_SHUTCOMP 0x0010 /**< a packet containing a SHUTDOWN-COMPLETE chunk */
#define SN_SCTP_SHUTACK 0x0020 /**< a packet containing a SHUTDOWN-ACK chunk */
#define SN_SCTP_ASCONF 0x0100 /**< a packet containing an ASCONF chunk */
#define SN_SCTP_ASCONFACK 0x0200 /**< a packet containing an ASCONF-ACK chunk */
#define SN_SCTP_OTHER 0xFFFF /**< a packet containing a chunk that is not of interest */
/** @}
* @defgroup state_machine SCTP NAT State Machine
*
* Defines the various states an association can be within the NAT @{
*/
#define SN_ID 0x0000 /**< Idle state */
#define SN_INi 0x0010 /**< Initialising, waiting for InitAck state */
#define SN_INa 0x0020 /**< Initialising, waiting for AddIpAck state */
#define SN_UP 0x0100 /**< Association in UP state */
#define SN_CL 0x1000 /**< Closing state */
#define SN_RM 0x2000 /**< Removing state */
/** @}
* @defgroup Logging Logging Functionality
*
* Define various log levels and a macro to call specified log functions only if
* the current log level (sysctl_log_level) matches the specified level @{
*/
#define SN_LOG_LOW 0
#define SN_LOG_EVENT 1
#define SN_LOG_INFO 2
#define SN_LOG_DETAIL 3
#define SN_LOG_DEBUG 4
#define SN_LOG_DEBUG_MAX 5
#define SN_LOG(level, action) if (sysctl_log_level >= level) { action; } /**< Perform log action ONLY if the current log level meets the specified log level */
/** @}
* @defgroup Hash Hash Table Macros and Functions
*
* Defines minimum/maximum/default values for the hash table size @{
*/
#define SN_MIN_HASH_SIZE 101 /**< Minimum hash table size (set to stop users choosing stupid values) */
#define SN_MAX_HASH_SIZE 1000001 /**< Maximum hash table size (NB must be less than max int) */
#define SN_DEFAULT_HASH_SIZE 2003 /**< A reasonable default size for the hash tables */
#define SN_LOCAL_TBL 0x01 /**< assoc in local table */
#define SN_GLOBAL_TBL 0x02 /**< assoc in global table */
#define SN_BOTH_TBL 0x03 /**< assoc in both tables */
#define SN_WAIT_TOLOCAL 0x10 /**< assoc waiting for TOLOCAL asconf ACK*/
#define SN_WAIT_TOGLOBAL 0x20 /**< assoc waiting for TOLOCAL asconf ACK*/
#define SN_NULL_TBL 0x00 /**< assoc in No table */
#define SN_MAX_GLOBAL_ADDRESSES 100 /**< absolute maximum global address count*/
#define SN_ADD_OK 0 /**< Association added to the table */
#define SN_ADD_CLASH 1 /**< Clash when trying to add the assoc. info to the table */
#define SN_TABLE_HASH(vtag, port, size) (((u_int) vtag + (u_int) port) % (u_int) size) /**< Calculate the hash table lookup position */
/** @}
* @defgroup Timer Timer Queue Macros and Functions
*
* Timer macros set minimum/maximum timeout values and calculate timer expiry
* times for the provided libalias instance @{
*/
#define SN_MIN_TIMER 1
#define SN_MAX_TIMER 600
#define SN_TIMER_QUEUE_SIZE SN_MAX_TIMER+2
#define SN_I_T(la) (la->timeStamp + sysctl_init_timer) /**< INIT State expiration time in seconds */
#define SN_U_T(la) (la->timeStamp + sysctl_up_timer) /**< UP State expiration time in seconds */
#define SN_C_T(la) (la->timeStamp + sysctl_shutdown_timer) /**< CL State expiration time in seconds */
#define SN_X_T(la) (la->timeStamp + sysctl_holddown_timer) /**< Wait after a shutdown complete in seconds */
/** @}
* @defgroup sysctl SysCtl Variable and callback function declarations
*
* Sysctl variables to modify NAT functionality in real-time along with associated functions
* to manage modifications to the sysctl variables @{
*/
/* Callbacks */
int sysctl_chg_loglevel(SYSCTL_HANDLER_ARGS);
int sysctl_chg_timer(SYSCTL_HANDLER_ARGS);
int sysctl_chg_hashtable_size(SYSCTL_HANDLER_ARGS);
int sysctl_chg_error_on_ootb(SYSCTL_HANDLER_ARGS);
int sysctl_chg_accept_global_ootb_addip(SYSCTL_HANDLER_ARGS);
int sysctl_chg_initialising_chunk_proc_limit(SYSCTL_HANDLER_ARGS);
int sysctl_chg_chunk_proc_limit(SYSCTL_HANDLER_ARGS);
int sysctl_chg_param_proc_limit(SYSCTL_HANDLER_ARGS);
int sysctl_chg_track_global_addresses(SYSCTL_HANDLER_ARGS);
/* Sysctl variables */
/** @brief net.inet.ip.alias.sctp.log_level */
static u_int sysctl_log_level = 0; /**< Stores the current level of logging */
/** @brief net.inet.ip.alias.sctp.init_timer */
static u_int sysctl_init_timer = 15; /**< Seconds to hold an association in the table waiting for an INIT-ACK or AddIP-ACK */
/** @brief net.inet.ip.alias.sctp.up_timer */
static u_int sysctl_up_timer = 300; /**< Seconds to hold an association in the table while no packets are transmitted */
/** @brief net.inet.ip.alias.sctp.shutdown_timer */
static u_int sysctl_shutdown_timer = 15; /**< Seconds to hold an association in the table waiting for a SHUTDOWN-COMPLETE */
/** @brief net.inet.ip.alias.sctp.holddown_timer */
static u_int sysctl_holddown_timer = 0; /**< Seconds to hold an association in the table after it has been shutdown (to allow for lost SHUTDOWN-COMPLETEs) */
/** @brief net.inet.ip.alias.sctp.hashtable_size */
static u_int sysctl_hashtable_size = SN_DEFAULT_HASH_SIZE; /**< Sets the hash table size for any NEW NAT instances (existing instances retain their existing Hash Table */
/** @brief net.inet.ip.alias.sctp.error_on_ootb */
static u_int sysctl_error_on_ootb = 1; /**< NAT response to receipt of OOTB packet
(0 - No response, 1 - NAT will send ErrorM only to local side,
2 - NAT will send local ErrorM and global ErrorM if there was a partial association match
3 - NAT will send ErrorM to both local and global) */
/** @brief net.inet.ip.alias.sctp.accept_global_ootb_addip */
static u_int sysctl_accept_global_ootb_addip = 0; /**<NAT responset to receipt of global OOTB AddIP (0 - No response, 1 - NAT will accept OOTB global AddIP messages for processing (Security risk)) */
/** @brief net.inet.ip.alias.sctp.initialising_chunk_proc_limit */
static u_int sysctl_initialising_chunk_proc_limit = 2; /**< A limit on the number of chunks that should be searched if there is no matching association (DoS prevention) */
/** @brief net.inet.ip.alias.sctp.param_proc_limit */
static u_int sysctl_chunk_proc_limit = 5; /**< A limit on the number of chunks that should be searched (DoS prevention) */
/** @brief net.inet.ip.alias.sctp.param_proc_limit */
static u_int sysctl_param_proc_limit = 25; /**< A limit on the number of parameters (in chunks) that should be searched (DoS prevention) */
/** @brief net.inet.ip.alias.sctp.track_global_addresses */
static u_int sysctl_track_global_addresses = 0; /**< Configures the global address tracking option within the NAT (0 - Global tracking is disabled, > 0 - enables tracking but limits the number of global IP addresses to this value)
If set to >=1 the NAT will track that many global IP addresses. This may reduce look up table conflicts, but increases processing */
#define SN_NO_ERROR_ON_OOTB 0 /**< Send no errorM on out of the blue packets */
#define SN_LOCAL_ERROR_ON_OOTB 1 /**< Send only local errorM on out of the blue packets */
#define SN_LOCALandPARTIAL_ERROR_ON_OOTB 2 /**< Send local errorM and global errorM for out of the blue packets only if partial match found */
#define SN_ERROR_ON_OOTB 3 /**< Send errorM on out of the blue packets */
#ifdef SYSCTL_NODE
SYSCTL_DECL(_net_inet);
SYSCTL_DECL(_net_inet_ip);
SYSCTL_DECL(_net_inet_ip_alias);
SYSCTL_NODE(_net_inet_ip_alias, OID_AUTO, sctp, CTLFLAG_RW, NULL, "SCTP NAT");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, log_level, CTLTYPE_UINT | CTLFLAG_RW,
&sysctl_log_level, 0, sysctl_chg_loglevel, "IU",
"Level of detail (0 - default, 1 - event, 2 - info, 3 - detail, 4 - debug, 5 - max debug)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, init_timer, CTLTYPE_UINT | CTLFLAG_RW,
&sysctl_init_timer, 0, sysctl_chg_timer, "IU",
"Timeout value (s) while waiting for (INIT-ACK|AddIP-ACK)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, up_timer, CTLTYPE_UINT | CTLFLAG_RW,
&sysctl_up_timer, 0, sysctl_chg_timer, "IU",
"Timeout value (s) to keep an association up with no traffic");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, shutdown_timer, CTLTYPE_UINT | CTLFLAG_RW,
&sysctl_shutdown_timer, 0, sysctl_chg_timer, "IU",
"Timeout value (s) while waiting for SHUTDOWN-COMPLETE");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, holddown_timer, CTLTYPE_UINT | CTLFLAG_RW,
&sysctl_holddown_timer, 0, sysctl_chg_timer, "IU",
"Hold association in table for this many seconds after receiving a SHUTDOWN-COMPLETE");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, hashtable_size, CTLTYPE_UINT | CTLFLAG_RW,
&sysctl_hashtable_size, 0, sysctl_chg_hashtable_size, "IU",
"Size of hash tables used for NAT lookups (100 < prime_number > 1000001)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, error_on_ootb, CTLTYPE_UINT | CTLFLAG_RW,
&sysctl_error_on_ootb, 0, sysctl_chg_error_on_ootb, "IU",
"ErrorM sent on receipt of ootb packet:\n\t0 - none,\n\t1 - to local only,\n\t2 - to local and global if a partial association match,\n\t3 - to local and global (DoS risk)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, accept_global_ootb_addip, CTLTYPE_UINT | CTLFLAG_RW,
&sysctl_accept_global_ootb_addip, 0, sysctl_chg_accept_global_ootb_addip, "IU",
"NAT response to receipt of global OOTB AddIP:\n\t0 - No response,\n\t1 - NAT will accept OOTB global AddIP messages for processing (Security risk)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, initialising_chunk_proc_limit, CTLTYPE_UINT | CTLFLAG_RW,
&sysctl_initialising_chunk_proc_limit, 0, sysctl_chg_initialising_chunk_proc_limit, "IU",
"Number of chunks that should be processed if there is no current association found:\n\t > 0 (A high value is a DoS risk)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, chunk_proc_limit, CTLTYPE_UINT | CTLFLAG_RW,
&sysctl_chunk_proc_limit, 0, sysctl_chg_chunk_proc_limit, "IU",
"Number of chunks that should be processed to find key chunk:\n\t>= initialising_chunk_proc_limit (A high value is a DoS risk)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, param_proc_limit, CTLTYPE_UINT | CTLFLAG_RW,
&sysctl_param_proc_limit, 0, sysctl_chg_param_proc_limit, "IU",
"Number of parameters (in a chunk) that should be processed to find key parameters:\n\t> 1 (A high value is a DoS risk)");
SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, track_global_addresses, CTLTYPE_UINT | CTLFLAG_RW,
&sysctl_track_global_addresses, 0, sysctl_chg_track_global_addresses, "IU",
"Configures the global address tracking option within the NAT:\n\t0 - Global tracking is disabled,\n\t> 0 - enables tracking but limits the number of global IP addresses to this value");
#endif /* SYSCTL_NODE */
/** @}
* @ingroup sysctl
* @brief sysctl callback for changing net.inet.ip.fw.sctp.log_level
*
* Updates the variable sysctl_log_level to the provided value and ensures
* it is in the valid range (SN_LOG_LOW -> SN_LOG_DEBUG)
*/
int sysctl_chg_loglevel(SYSCTL_HANDLER_ARGS)
{
u_int level = *(u_int *)arg1;
int error;
error = sysctl_handle_int(oidp, &level, 0, req);
if (error) return (error);
sysctl_log_level = (level > SN_LOG_DEBUG_MAX)?(SN_LOG_DEBUG_MAX):(level);
sysctl_log_level = (level < SN_LOG_LOW)?(SN_LOG_LOW):(level);
return (0);
}
/** @ingroup sysctl
* @brief sysctl callback for changing net.inet.ip.fw.sctp.(init_timer|up_timer|shutdown_timer)
*
* Updates the timer-based sysctl variables. The new values are sanity-checked
* to make sure that they are within the range SN_MIN_TIMER-SN_MAX_TIMER. The
* holddown timer is allowed to be 0
*/
int sysctl_chg_timer(SYSCTL_HANDLER_ARGS)
{
u_int timer = *(u_int *)arg1;
int error;
error = sysctl_handle_int(oidp, &timer, 0, req);
if (error) return (error);
timer = (timer > SN_MAX_TIMER)?(SN_MAX_TIMER):(timer);
if (((u_int *)arg1) != &sysctl_holddown_timer)
{
timer = (timer < SN_MIN_TIMER)?(SN_MIN_TIMER):(timer);
}
*(u_int *)arg1 = timer;
return (0);
}
/** @ingroup sysctl
* @brief sysctl callback for changing net.inet.ip.alias.sctp.hashtable_size
*
* Updates the hashtable_size sysctl variable. The new value should be a prime
* number. We sanity check to ensure that the size is within the range
* SN_MIN_HASH_SIZE-SN_MAX_HASH_SIZE. We then check the provided number to see
* if it is prime. We approximate by checking that (2,3,5,7,11) are not factors,
* incrementing the user provided value until we find a suitable number.
*/
int sysctl_chg_hashtable_size(SYSCTL_HANDLER_ARGS)
{
u_int size = *(u_int *)arg1;
int error;
error = sysctl_handle_int(oidp, &size, 0, req);
if (error) return (error);
size = (size < SN_MIN_HASH_SIZE)?(SN_MIN_HASH_SIZE):((size > SN_MAX_HASH_SIZE)?(SN_MAX_HASH_SIZE):(size));
size |= 0x00000001; /* make odd */
for(;(((size % 3) == 0) || ((size % 5) == 0) || ((size % 7) == 0) || ((size % 11) == 0)); size+=2);
sysctl_hashtable_size = size;
return (0);
}
/** @ingroup sysctl
* @brief sysctl callback for changing net.inet.ip.alias.sctp.error_on_ootb
*
* Updates the error_on_clash sysctl variable.
* If set to 0, no ErrorM will be sent if there is a look up table clash
* If set to 1, an ErrorM is sent only to the local side
* If set to 2, an ErrorM is sent to the local side and global side if there is
* a partial association match
* If set to 3, an ErrorM is sent to both local and global sides (DoS) risk.
*/
int sysctl_chg_error_on_ootb(SYSCTL_HANDLER_ARGS)
{
u_int flag = *(u_int *)arg1;
int error;
error = sysctl_handle_int(oidp, &flag, 0, req);
if (error) return (error);
sysctl_error_on_ootb = (flag > SN_ERROR_ON_OOTB) ? SN_ERROR_ON_OOTB: flag;
return (0);
}
/** @ingroup sysctl
* @brief sysctl callback for changing net.inet.ip.alias.sctp.accept_global_ootb_addip
*
* If set to 1 the NAT will accept ootb global addip messages for processing (Security risk)
* Default is 0, only responding to local ootb AddIP messages
*/
int sysctl_chg_accept_global_ootb_addip(SYSCTL_HANDLER_ARGS)
{
u_int flag = *(u_int *)arg1;
int error;
error = sysctl_handle_int(oidp, &flag, 0, req);
if (error) return (error);
sysctl_accept_global_ootb_addip = (flag == 1) ? 1: 0;
return (0);
}
/** @ingroup sysctl
* @brief sysctl callback for changing net.inet.ip.alias.sctp.initialising_chunk_proc_limit
*
* Updates the initialising_chunk_proc_limit sysctl variable. Number of chunks
* that should be processed if there is no current association found: > 0 (A
* high value is a DoS risk)
*/
int sysctl_chg_initialising_chunk_proc_limit(SYSCTL_HANDLER_ARGS)
{
u_int proclimit = *(u_int *)arg1;
int error;
error = sysctl_handle_int(oidp, &proclimit, 0, req);
if (error) return (error);
sysctl_initialising_chunk_proc_limit = (proclimit < 1) ? 1: proclimit;
sysctl_chunk_proc_limit =
(sysctl_chunk_proc_limit < sysctl_initialising_chunk_proc_limit) ? sysctl_initialising_chunk_proc_limit : sysctl_chunk_proc_limit;
return (0);
}
/** @ingroup sysctl
* @brief sysctl callback for changing net.inet.ip.alias.sctp.chunk_proc_limit
*
* Updates the chunk_proc_limit sysctl variable.
* Number of chunks that should be processed to find key chunk:
* >= initialising_chunk_proc_limit (A high value is a DoS risk)
*/
int sysctl_chg_chunk_proc_limit(SYSCTL_HANDLER_ARGS)
{
u_int proclimit = *(u_int *)arg1;
int error;
error = sysctl_handle_int(oidp, &proclimit, 0, req);
if (error) return (error);
sysctl_chunk_proc_limit =
(proclimit < sysctl_initialising_chunk_proc_limit) ? sysctl_initialising_chunk_proc_limit : proclimit;
return (0);
}
/** @ingroup sysctl
* @brief sysctl callback for changing net.inet.ip.alias.sctp.param_proc_limit
*
* Updates the param_proc_limit sysctl variable.
* Number of parameters that should be processed to find key parameters:
* > 1 (A high value is a DoS risk)
*/
int sysctl_chg_param_proc_limit(SYSCTL_HANDLER_ARGS)
{
u_int proclimit = *(u_int *)arg1;
int error;
error = sysctl_handle_int(oidp, &proclimit, 0, req);
if (error) return (error);
sysctl_param_proc_limit =
(proclimit < 2) ? 2 : proclimit;
return (0);
}
/** @ingroup sysctl
* @brief sysctl callback for changing net.inet.ip.alias.sctp.track_global_addresses
*
*Configures the global address tracking option within the NAT (0 - Global
*tracking is disabled, > 0 - enables tracking but limits the number of global
*IP addresses to this value)
*/
int sysctl_chg_track_global_addresses(SYSCTL_HANDLER_ARGS)
{
u_int num_to_track = *(u_int *)arg1;
int error;
error = sysctl_handle_int(oidp, &num_to_track, 0, req);
if (error) return (error);
sysctl_track_global_addresses = (num_to_track > SN_MAX_GLOBAL_ADDRESSES) ? SN_MAX_GLOBAL_ADDRESSES : num_to_track;
return (0);
}
/* ----------------------------------------------------------------------
* CODE BEGINS HERE
* ----------------------------------------------------------------------
*/
/**
* @brief Initialises the SCTP NAT Implementation
*
* Creates the look-up tables and the timer queue and initialises all state
* variables
*
* @param la Pointer to the relevant libalias instance
*/
void AliasSctpInit(struct libalias *la)
{
/* Initialise association tables*/
int i;
la->sctpNatTableSize = sysctl_hashtable_size;
SN_LOG(SN_LOG_EVENT,
SctpAliasLog("Initialising SCTP NAT Instance (hash_table_size:%d)\n", la->sctpNatTableSize));
la->sctpTableLocal = sn_calloc(la->sctpNatTableSize, sizeof(struct sctpNatTableL));
la->sctpTableGlobal = sn_calloc(la->sctpNatTableSize, sizeof(struct sctpNatTableG));
la->sctpNatTimer.TimerQ = sn_calloc(SN_TIMER_QUEUE_SIZE, sizeof(struct sctpTimerQ));
/* Initialise hash table */
for (i = 0; i < la->sctpNatTableSize; i++) {
LIST_INIT(&la->sctpTableLocal[i]);
LIST_INIT(&la->sctpTableGlobal[i]);
}
/* Initialise circular timer Q*/
for (i = 0; i < SN_TIMER_QUEUE_SIZE; i++)
LIST_INIT(&la->sctpNatTimer.TimerQ[i]);
#ifdef _KERNEL
la->sctpNatTimer.loc_time=time_uptime; /* la->timeStamp is not set yet */
#else
la->sctpNatTimer.loc_time=la->timeStamp;
#endif
la->sctpNatTimer.cur_loc = 0;
la->sctpLinkCount = 0;
}
/**
* @brief Cleans-up the SCTP NAT Implementation prior to unloading
*
* Removes all entries from the timer queue, freeing associations as it goes.
* We then free memory allocated to the look-up tables and the time queue
*
* NOTE: We do not need to traverse the look-up tables as each association
* will always have an entry in the timer queue, freeing this memory
* once will free all memory allocated to entries in the look-up tables
*
* @param la Pointer to the relevant libalias instance
*/
void AliasSctpTerm(struct libalias *la)
{
struct sctp_nat_assoc *assoc1, *assoc2;
int i;
LIBALIAS_LOCK_ASSERT(la);
SN_LOG(SN_LOG_EVENT,
SctpAliasLog("Removing SCTP NAT Instance\n"));
for (i = 0; i < SN_TIMER_QUEUE_SIZE; i++) {
assoc1 = LIST_FIRST(&la->sctpNatTimer.TimerQ[i]);
while (assoc1 != NULL) {
freeGlobalAddressList(assoc1);
assoc2 = LIST_NEXT(assoc1, timer_Q);
sn_free(assoc1);
assoc1 = assoc2;
}
}
sn_free(la->sctpTableLocal);
sn_free(la->sctpTableGlobal);
sn_free(la->sctpNatTimer.TimerQ);
}
/**
* @brief Handles SCTP packets passed from libalias
*
* This function needs to actually NAT/drop packets and possibly create and
* send AbortM or ErrorM packets in response. The process involves:
* - Validating the direction parameter passed by the caller
* - Checking and handling any expired timers for the NAT
* - Calling sctp_PktParser() to parse the packet
* - Call ProcessSctpMsg() to decide the appropriate outcome and to update
* the NAT tables
* - Based on the return code either:
* - NAT the packet
* - Construct and send an ErrorM|AbortM packet
* - Mark the association for removal from the tables
* - Potentially remove the association from all lookup tables
* - Return the appropriate result to libalias
*
* @param la Pointer to the relevant libalias instance
* @param pip Pointer to IP packet to process
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
*
* @return PKT_ALIAS_OK | PKT_ALIAS_IGNORE | PKT_ALIAS_ERROR
*/
int
SctpAlias(struct libalias *la, struct ip *pip, int direction)
{
int rtnval;
struct sctp_nat_msg msg;
struct sctp_nat_assoc *assoc = NULL;
if ((direction != SN_TO_LOCAL) && (direction != SN_TO_GLOBAL)) {
SctpAliasLog("ERROR: Invalid direction\n");
return(PKT_ALIAS_ERROR);
}
sctp_CheckTimers(la); /* Check timers */
/* Parse the packet */
rtnval = sctp_PktParser(la, direction, pip, &msg, &assoc); //using *char (change to mbuf when get code from paolo)
switch (rtnval) {
case SN_PARSE_OK:
break;
case SN_PARSE_ERROR_CHHL:
/* Not an error if there is a chunk length parsing error and this is a fragmented packet */
if (ntohs(pip->ip_off) & IP_MF) {
rtnval = SN_PARSE_OK;
break;
}
SN_LOG(SN_LOG_EVENT,
logsctperror("SN_PARSE_ERROR", msg.sctp_hdr->v_tag, rtnval, direction));
return(PKT_ALIAS_ERROR);
case SN_PARSE_ERROR_PARTIALLOOKUP:
if (sysctl_error_on_ootb > SN_LOCALandPARTIAL_ERROR_ON_OOTB) {
SN_LOG(SN_LOG_EVENT,
logsctperror("SN_PARSE_ERROR", msg.sctp_hdr->v_tag, rtnval, direction));
return(PKT_ALIAS_ERROR);
}
case SN_PARSE_ERROR_LOOKUP:
if (sysctl_error_on_ootb == SN_ERROR_ON_OOTB ||
(sysctl_error_on_ootb == SN_LOCALandPARTIAL_ERROR_ON_OOTB && direction == SN_TO_LOCAL) ||
(sysctl_error_on_ootb == SN_LOCAL_ERROR_ON_OOTB && direction == SN_TO_GLOBAL)) {
TxAbortErrorM(la, &msg, assoc, SN_REFLECT_ERROR, direction); /*NB assoc=NULL */
return(PKT_ALIAS_RESPOND);
}
default:
SN_LOG(SN_LOG_EVENT,
logsctperror("SN_PARSE_ERROR", msg.sctp_hdr->v_tag, rtnval, direction));
return(PKT_ALIAS_ERROR);
}
SN_LOG(SN_LOG_DETAIL,
logsctpassoc(assoc, "*");
logsctpparse(direction, &msg);
);
/* Process the SCTP message */
rtnval = ProcessSctpMsg(la, direction, &msg, assoc);
SN_LOG(SN_LOG_DEBUG_MAX,
logsctpassoc(assoc, "-");
logSctpLocal(la);
logSctpGlobal(la);
);
SN_LOG(SN_LOG_DEBUG, logTimerQ(la));
switch(rtnval){
case SN_NAT_PKT:
switch(direction) {
case SN_TO_LOCAL:
DifferentialChecksum(&(msg.ip_hdr->ip_sum),
&(assoc->l_addr), &(msg.ip_hdr->ip_dst), 2);
msg.ip_hdr->ip_dst = assoc->l_addr; /* change dst address to local address*/
break;
case SN_TO_GLOBAL:
DifferentialChecksum(&(msg.ip_hdr->ip_sum),
&(assoc->a_addr), &(msg.ip_hdr->ip_src), 2);
msg.ip_hdr->ip_src = assoc->a_addr; /* change src to alias addr*/
break;
default:
rtnval = SN_DROP_PKT; /* shouldn't get here, but if it does drop packet */
SN_LOG(SN_LOG_LOW, logsctperror("ERROR: Invalid direction", msg.sctp_hdr->v_tag, rtnval, direction));
break;
}
break;
case SN_DROP_PKT:
SN_LOG(SN_LOG_DETAIL, logsctperror("SN_DROP_PKT", msg.sctp_hdr->v_tag, rtnval, direction));
break;
case SN_REPLY_ABORT:
case SN_REPLY_ERROR:
case SN_SEND_ABORT:
TxAbortErrorM(la, &msg, assoc, rtnval, direction);
break;
default:
// big error, remove association and go to idle and write log messages
SN_LOG(SN_LOG_LOW, logsctperror("SN_PROCESSING_ERROR", msg.sctp_hdr->v_tag, rtnval, direction));
assoc->state=SN_RM;/* Mark for removal*/
break;
}
/* Remove association if tagged for removal */
if (assoc->state == SN_RM) {
if (assoc->TableRegister) {
sctp_RmTimeOut(la, assoc);
RmSctpAssoc(la, assoc);
}
LIBALIAS_LOCK_ASSERT(la);
freeGlobalAddressList(assoc);
sn_free(assoc);
}
switch(rtnval) {
case SN_NAT_PKT:
return(PKT_ALIAS_OK);
case SN_SEND_ABORT:
return(PKT_ALIAS_OK);
case SN_REPLY_ABORT:
case SN_REPLY_ERROR:
case SN_REFLECT_ERROR:
return(PKT_ALIAS_RESPOND);
case SN_DROP_PKT:
default:
return(PKT_ALIAS_ERROR);
}
}
/**
* @brief Send an AbortM or ErrorM
*
* We construct the new SCTP packet to send in place of the existing packet we
* have been asked to NAT. This function can only be called if the original
* packet was successfully parsed as a valid SCTP packet.
*
* An AbortM (without cause) packet is the smallest SCTP packet available and as
* such there is always space in the existing packet buffer to fit the AbortM
* packet. An ErrorM packet is 4 bytes longer than the (the error cause is not
* optional). An ErrorM is sent in response to an AddIP when the Vtag/address
* combination, if added, will produce a conflict in the association look up
* tables. It may also be used for an unexpected packet - a packet with no
* matching association in the NAT table and we are requesting an AddIP so we
* can add it. The smallest valid SCTP packet while the association is in an
* up-state is a Heartbeat packet, which is big enough to be transformed to an
* ErrorM.
*
* We create a temporary character array to store the packet as we are constructing
* it. We then populate the array with appropriate values based on:
* - Packet type (AbortM | ErrorM)
* - Initial packet direction (SN_TO_LOCAL | SN_TO_GLOBAL)
* - NAT response (Send packet | Reply packet)
*
* Once complete, we copy the contents of the temporary packet over the original
* SCTP packet we were asked to NAT
*
* @param la Pointer to the relevant libalias instance
* @param sm Pointer to sctp message information
* @param assoc Pointer to current association details
* @param sndrply SN_SEND_ABORT | SN_REPLY_ABORT | SN_REPLY_ERROR
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
*/
static uint32_t
local_sctp_finalize_crc32(uint32_t crc32c)
{
/* This routine is duplicated from SCTP
* we need to do that since it MAY be that SCTP
* is NOT compiled into the kernel. The CRC32C routines
* however are always available in libkern.
*/
uint32_t result;
#if BYTE_ORDER == BIG_ENDIAN
uint8_t byte0, byte1, byte2, byte3;
#endif
/* Complement the result */
result = ~crc32c;
#if BYTE_ORDER == BIG_ENDIAN
/*
* For BIG-ENDIAN.. aka Motorola byte order the result is in
* little-endian form. So we must manually swap the bytes. Then we
* can call htonl() which does nothing...
*/
byte0 = result & 0x000000ff;
byte1 = (result >> 8) & 0x000000ff;
byte2 = (result >> 16) & 0x000000ff;
byte3 = (result >> 24) & 0x000000ff;
crc32c = ((byte0 << 24) | (byte1 << 16) | (byte2 << 8) | byte3);
#else
/*
* For INTEL platforms the result comes out in network order. No
* htonl is required or the swap above. So we optimize out both the
* htonl and the manual swap above.
*/
crc32c = result;
#endif
return (crc32c);
}
static void
TxAbortErrorM(struct libalias *la, struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc, int sndrply, int direction)
{
int sctp_size = sizeof(struct sctphdr) + sizeof(struct sctp_chunkhdr) + sizeof(struct sctp_error_cause);
int ip_size = sizeof(struct ip) + sctp_size;
int include_error_cause = 1;
char tmp_ip[ip_size];
if (ntohs(sm->ip_hdr->ip_len) < ip_size) { /* short packet, cannot send error cause */
include_error_cause = 0;
ip_size = ip_size - sizeof(struct sctp_error_cause);
sctp_size = sctp_size - sizeof(struct sctp_error_cause);
}
/* Assign header pointers packet */
struct ip* ip = (struct ip *) tmp_ip;
struct sctphdr* sctp_hdr = (struct sctphdr *) ((char *) ip + sizeof(*ip));
struct sctp_chunkhdr* chunk_hdr = (struct sctp_chunkhdr *) ((char *) sctp_hdr + sizeof(*sctp_hdr));
struct sctp_error_cause* error_cause = (struct sctp_error_cause *) ((char *) chunk_hdr + sizeof(*chunk_hdr));
/* construct ip header */
ip->ip_v = sm->ip_hdr->ip_v;
ip->ip_hl = 5; /* 5*32 bit words */
ip->ip_tos = 0;
ip->ip_len = htons(ip_size);
ip->ip_id = sm->ip_hdr->ip_id;
ip->ip_off = 0;
ip->ip_ttl = 255;
ip->ip_p = IPPROTO_SCTP;
/*
The definitions below should be removed when they make it into the SCTP stack
*/
#define SCTP_MIDDLEBOX_FLAG 0x02
#define SCTP_NAT_TABLE_COLLISION 0x00b0
#define SCTP_MISSING_NAT 0x00b1
chunk_hdr->chunk_type = (sndrply & SN_TX_ABORT) ? SCTP_ABORT_ASSOCIATION : SCTP_OPERATION_ERROR;
chunk_hdr->chunk_flags = SCTP_MIDDLEBOX_FLAG;
if (include_error_cause) {
error_cause->code = htons((sndrply & SN_REFLECT_ERROR) ? SCTP_MISSING_NAT : SCTP_NAT_TABLE_COLLISION);
error_cause->length = htons(sizeof(struct sctp_error_cause));
chunk_hdr->chunk_length = htons(sizeof(*chunk_hdr) + sizeof(struct sctp_error_cause));
} else {
chunk_hdr->chunk_length = htons(sizeof(*chunk_hdr));
}
/* set specific values */
switch(sndrply) {
case SN_REFLECT_ERROR:
chunk_hdr->chunk_flags |= SCTP_HAD_NO_TCB; /* set Tbit */
sctp_hdr->v_tag = sm->sctp_hdr->v_tag;
break;
case SN_REPLY_ERROR:
sctp_hdr->v_tag = (direction == SN_TO_LOCAL) ? assoc->g_vtag : assoc->l_vtag ;
break;
case SN_SEND_ABORT:
sctp_hdr->v_tag = sm->sctp_hdr->v_tag;
break;
case SN_REPLY_ABORT:
sctp_hdr->v_tag = sm->sctpchnk.Init->initiate_tag;
break;
}
/* Set send/reply values */
if (sndrply == SN_SEND_ABORT) { /*pass through NAT */
ip->ip_src = (direction == SN_TO_LOCAL) ? sm->ip_hdr->ip_src : assoc->a_addr;
ip->ip_dst = (direction == SN_TO_LOCAL) ? assoc->l_addr : sm->ip_hdr->ip_dst;
sctp_hdr->src_port = sm->sctp_hdr->src_port;
sctp_hdr->dest_port = sm->sctp_hdr->dest_port;
} else { /* reply and reflect */
ip->ip_src = sm->ip_hdr->ip_dst;
ip->ip_dst = sm->ip_hdr->ip_src;
sctp_hdr->src_port = sm->sctp_hdr->dest_port;
sctp_hdr->dest_port = sm->sctp_hdr->src_port;
}
/* Calculate IP header checksum */
ip->ip_sum = in_cksum_hdr(ip);
/* calculate SCTP header CRC32 */
sctp_hdr->checksum = 0;
sctp_hdr->checksum = local_sctp_finalize_crc32(calculate_crc32c(0xffffffff, (unsigned char *) sctp_hdr, sctp_size));
memcpy(sm->ip_hdr, ip, ip_size);
SN_LOG(SN_LOG_EVENT,SctpAliasLog("%s %s 0x%x (->%s:%u vtag=0x%x crc=0x%x)\n",
((sndrply == SN_SEND_ABORT) ? "Sending" : "Replying"),
((sndrply & SN_TX_ERROR) ? "ErrorM" : "AbortM"),
(include_error_cause ? ntohs(error_cause->code) : 0),
inet_ntoa(ip->ip_dst),ntohs(sctp_hdr->dest_port),
ntohl(sctp_hdr->v_tag), ntohl(sctp_hdr->checksum)));
}
/* ----------------------------------------------------------------------
* PACKET PARSER CODE
* ----------------------------------------------------------------------
*/
/** @addtogroup packet_parser
*
* These functions parse the SCTP packet and fill a sctp_nat_msg structure
* with the parsed contents.
*/
/** @ingroup packet_parser
* @brief Parses SCTP packets for the key SCTP chunk that will be processed
*
* This module parses SCTP packets for the key SCTP chunk that will be processed
* The module completes the sctp_nat_msg structure and either retrieves the
* relevant (existing) stored association from the Hash Tables or creates a new
* association entity with state SN_ID
*
* @param la Pointer to the relevant libalias instance
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
* @param pip
* @param sm Pointer to sctp message information
* @param passoc Pointer to the association this SCTP Message belongs to
*
* @return SN_PARSE_OK | SN_PARSE_ERROR_*
*/
static int
sctp_PktParser(struct libalias *la, int direction, struct ip *pip,
struct sctp_nat_msg *sm, struct sctp_nat_assoc **passoc)
//sctp_PktParser(int direction, struct mbuf *ipak, int ip_hdr_len,struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc)
{
struct sctphdr *sctp_hdr;
struct sctp_chunkhdr *chunk_hdr;
struct sctp_paramhdr *param_hdr;
struct in_addr ipv4addr;
int bytes_left; /* bytes left in ip packet */
int chunk_length;
int chunk_count;
int partial_match = 0;
// mbuf *mp;
// int mlen;
// mlen = SCTP_HEADER_LEN(i_pak);
// mp = SCTP_HEADER_TO_CHAIN(i_pak); /* does nothing in bsd since header and chain not separate */
/*
* Note, that if the VTag is zero, it must be an INIT
* Also, I am only interested in the content of INIT and ADDIP chunks
*/
// no mbuf stuff from Paolo yet so ...
sm->ip_hdr = pip;
/* remove ip header length from the bytes_left */
bytes_left = ntohs(pip->ip_len) - (pip->ip_hl << 2);
/* Check SCTP header length and move to first chunk */
if (bytes_left < sizeof(struct sctphdr)) {
sm->sctp_hdr = NULL;
return(SN_PARSE_ERROR_IPSHL); /* packet not long enough*/
}
sm->sctp_hdr = sctp_hdr = (struct sctphdr *) ip_next(pip);
bytes_left -= sizeof(struct sctphdr);
/* Check for valid ports (zero valued ports would find partially initialised associations */
if (sctp_hdr->src_port == 0 || sctp_hdr->dest_port == 0)
return(SN_PARSE_ERROR_PORT);
/* Check length of first chunk */
if (bytes_left < SN_MIN_CHUNK_SIZE) /* malformed chunk - could cause endless loop*/
return(SN_PARSE_ERROR_CHHL); /* packet not long enough for this chunk */
/* First chunk */
chunk_hdr = SN_SCTP_FIRSTCHUNK(sctp_hdr);
chunk_length = SCTP_SIZE32(ntohs(chunk_hdr->chunk_length));
if ((chunk_length < SN_MIN_CHUNK_SIZE) || (chunk_length > bytes_left)) /* malformed chunk - could cause endless loop*/
return(SN_PARSE_ERROR_CHHL);
if ((chunk_hdr->chunk_flags & SCTP_HAD_NO_TCB) &&
((chunk_hdr->chunk_type == SCTP_ABORT_ASSOCIATION) ||
(chunk_hdr->chunk_type == SCTP_SHUTDOWN_COMPLETE))) {
/* T-Bit set */
if (direction == SN_TO_LOCAL)
*passoc = FindSctpGlobalT(la, pip->ip_src, sctp_hdr->v_tag, sctp_hdr->dest_port, sctp_hdr->src_port);
else
*passoc = FindSctpLocalT(la, pip->ip_dst, sctp_hdr->v_tag, sctp_hdr->dest_port, sctp_hdr->src_port);
} else {
/* Proper v_tag settings */
if (direction == SN_TO_LOCAL)
*passoc = FindSctpGlobal(la, pip->ip_src, sctp_hdr->v_tag, sctp_hdr->src_port, sctp_hdr->dest_port, &partial_match);
else
*passoc = FindSctpLocal(la, pip->ip_src, pip->ip_dst, sctp_hdr->v_tag, sctp_hdr->src_port, sctp_hdr->dest_port);
}
chunk_count = 1;
/* Real packet parsing occurs below */
sm->msg = SN_SCTP_OTHER;/* Initialise to largest value*/
sm->chunk_length = 0; /* only care about length for key chunks */
while (IS_SCTP_CONTROL(chunk_hdr)) {
switch(chunk_hdr->chunk_type) {
case SCTP_INITIATION:
if (chunk_length < sizeof(struct sctp_init_chunk)) /* malformed chunk*/
return(SN_PARSE_ERROR_CHHL);
sm->msg = SN_SCTP_INIT;
sm->sctpchnk.Init = (struct sctp_init *) ((char *) chunk_hdr + sizeof(struct sctp_chunkhdr));
sm->chunk_length = chunk_length;
/* if no existing association, create a new one */
if (*passoc == NULL) {
if (sctp_hdr->v_tag == 0){ //Init requires vtag=0
*passoc = (struct sctp_nat_assoc *) sn_malloc(sizeof(struct sctp_nat_assoc));
if (*passoc == NULL) {/* out of resources */
return(SN_PARSE_ERROR_AS_MALLOC);
}
/* Initialise association - malloc initialises memory to zeros */
(*passoc)->state = SN_ID;
LIST_INIT(&((*passoc)->Gaddr)); /* always initialise to avoid memory problems */
(*passoc)->TableRegister = SN_NULL_TBL;
return(SN_PARSE_OK);
}
return(SN_PARSE_ERROR_VTAG);
}
return(SN_PARSE_ERROR_LOOKUP);
case SCTP_INITIATION_ACK:
if (chunk_length < sizeof(struct sctp_init_ack_chunk)) /* malformed chunk*/
return(SN_PARSE_ERROR_CHHL);
sm->msg = SN_SCTP_INITACK;
sm->sctpchnk.InitAck = (struct sctp_init_ack *) ((char *) chunk_hdr + sizeof(struct sctp_chunkhdr));
sm->chunk_length = chunk_length;
return ((*passoc == NULL)?(SN_PARSE_ERROR_LOOKUP):(SN_PARSE_OK));
case SCTP_ABORT_ASSOCIATION: /* access only minimum sized chunk */
sm->msg = SN_SCTP_ABORT;
sm->chunk_length = chunk_length;
return ((*passoc == NULL)?(SN_PARSE_ERROR_LOOKUP_ABORT):(SN_PARSE_OK));
case SCTP_SHUTDOWN_ACK:
if (chunk_length < sizeof(struct sctp_shutdown_ack_chunk)) /* malformed chunk*/
return(SN_PARSE_ERROR_CHHL);
if (sm->msg > SN_SCTP_SHUTACK) {
sm->msg = SN_SCTP_SHUTACK;
sm->chunk_length = chunk_length;
}
break;
case SCTP_SHUTDOWN_COMPLETE: /* minimum sized chunk */
if (sm->msg > SN_SCTP_SHUTCOMP) {
sm->msg = SN_SCTP_SHUTCOMP;
sm->chunk_length = chunk_length;
}
return ((*passoc == NULL)?(SN_PARSE_ERROR_LOOKUP):(SN_PARSE_OK));
case SCTP_ASCONF:
if (sm->msg > SN_SCTP_ASCONF) {
if (chunk_length < (sizeof(struct sctp_asconf_chunk) + sizeof(struct sctp_ipv4addr_param))) /* malformed chunk*/
return(SN_PARSE_ERROR_CHHL);
//leave parameter searching to later, if required
param_hdr = (struct sctp_paramhdr *) ((char *) chunk_hdr + sizeof(struct sctp_asconf_chunk)); /*compulsory IP parameter*/
if (ntohs(param_hdr->param_type) == SCTP_IPV4_ADDRESS) {
if ((*passoc == NULL) && (direction == SN_TO_LOCAL)) { /* AddIP with no association */
/* try look up with the ASCONF packet's alternative address */
ipv4addr.s_addr = ((struct sctp_ipv4addr_param *) param_hdr)->addr;
*passoc = FindSctpGlobal(la, ipv4addr, sctp_hdr->v_tag, sctp_hdr->src_port, sctp_hdr->dest_port, &partial_match);
}
param_hdr = (struct sctp_paramhdr *)
((char *) param_hdr + sizeof(struct sctp_ipv4addr_param)); /*asconf's compulsory address parameter */
sm->chunk_length = chunk_length - sizeof(struct sctp_asconf_chunk) - sizeof(struct sctp_ipv4addr_param); /* rest of chunk */
} else {
if (chunk_length < (sizeof(struct sctp_asconf_chunk) + sizeof(struct sctp_ipv6addr_param))) /* malformed chunk*/
return(SN_PARSE_ERROR_CHHL);
param_hdr = (struct sctp_paramhdr *)
((char *) param_hdr + sizeof(struct sctp_ipv6addr_param)); /*asconf's compulsory address parameter */
sm->chunk_length = chunk_length - sizeof(struct sctp_asconf_chunk) - sizeof(struct sctp_ipv6addr_param); /* rest of chunk */
}
sm->msg = SN_SCTP_ASCONF;
sm->sctpchnk.Asconf = param_hdr;
if (*passoc == NULL) { /* AddIP with no association */
*passoc = (struct sctp_nat_assoc *) sn_malloc(sizeof(struct sctp_nat_assoc));
if (*passoc == NULL) {/* out of resources */
return(SN_PARSE_ERROR_AS_MALLOC);
}
/* Initialise association - malloc initialises memory to zeros */
(*passoc)->state = SN_ID;
LIST_INIT(&((*passoc)->Gaddr)); /* always initialise to avoid memory problems */
(*passoc)->TableRegister = SN_NULL_TBL;
return(SN_PARSE_OK);
}
}
break;
case SCTP_ASCONF_ACK:
if (sm->msg > SN_SCTP_ASCONFACK) {
if (chunk_length < sizeof(struct sctp_asconf_ack_chunk)) /* malformed chunk*/
return(SN_PARSE_ERROR_CHHL);
//leave parameter searching to later, if required
param_hdr = (struct sctp_paramhdr *) ((char *) chunk_hdr
+ sizeof(struct sctp_asconf_ack_chunk));
sm->msg = SN_SCTP_ASCONFACK;
sm->sctpchnk.Asconf = param_hdr;
sm->chunk_length = chunk_length - sizeof(struct sctp_asconf_ack_chunk);
}
break;
default:
break; /* do nothing*/
}
/* if no association is found exit - we need to find an Init or AddIP within sysctl_initialising_chunk_proc_limit */
if ((*passoc == NULL) && (chunk_count >= sysctl_initialising_chunk_proc_limit))
return(SN_PARSE_ERROR_LOOKUP);
/* finished with this chunk, on to the next chunk*/
bytes_left-= chunk_length;
/* Is this the end of the packet ? */
if (bytes_left == 0)
return (*passoc == NULL)?(SN_PARSE_ERROR_LOOKUP):(SN_PARSE_OK);
/* Are there enough bytes in packet to at least retrieve length of next chunk ? */
if (bytes_left < SN_MIN_CHUNK_SIZE)
return(SN_PARSE_ERROR_CHHL);
chunk_hdr = SN_SCTP_NEXTCHUNK(chunk_hdr);
/* Is the chunk long enough to not cause endless look and are there enough bytes in packet to read the chunk ? */
chunk_length = SCTP_SIZE32(ntohs(chunk_hdr->chunk_length));
if ((chunk_length < SN_MIN_CHUNK_SIZE) || (chunk_length > bytes_left))
return(SN_PARSE_ERROR_CHHL);
if(++chunk_count > sysctl_chunk_proc_limit)
return(SN_PARSE_OK); /* limit for processing chunks, take what we get */
}
if (*passoc == NULL)
return (partial_match)?(SN_PARSE_ERROR_PARTIALLOOKUP):(SN_PARSE_ERROR_LOOKUP);
else
return(SN_PARSE_OK);
}
/** @ingroup packet_parser
* @brief Extract Vtags from Asconf Chunk
*
* GetAsconfVtags scans an Asconf Chunk for the vtags parameter, and then
* extracts the vtags.
*
* GetAsconfVtags is not called from within sctp_PktParser. It is called only
* from within ID_process when an AddIP has been received.
*
* @param la Pointer to the relevant libalias instance
* @param sm Pointer to sctp message information
* @param l_vtag Pointer to the local vtag in the association this SCTP Message belongs to
* @param g_vtag Pointer to the local vtag in the association this SCTP Message belongs to
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
*
* @return 1 - success | 0 - fail
*/
static int
GetAsconfVtags(struct libalias *la, struct sctp_nat_msg *sm, uint32_t *l_vtag, uint32_t *g_vtag, int direction)
{
/* To be removed when information is in the sctp headers */
#define SCTP_VTAG_PARAM 0xC007
struct sctp_vtag_param {
struct sctp_paramhdr ph;/* type=SCTP_VTAG_PARAM */
uint32_t local_vtag;
uint32_t remote_vtag;
} __attribute__((packed));
struct sctp_vtag_param *vtag_param;
struct sctp_paramhdr *param;
int bytes_left;
int param_size;
int param_count;
param_count = 1;
param = sm->sctpchnk.Asconf;
param_size = SCTP_SIZE32(ntohs(param->param_length));
bytes_left = sm->chunk_length;
/* step through Asconf parameters */
while((bytes_left >= param_size) && (bytes_left >= SN_VTAG_PARAM_SIZE)) {
if (ntohs(param->param_type) == SCTP_VTAG_PARAM) {
vtag_param = (struct sctp_vtag_param *) param;
switch(direction) {
/* The Internet draft is a little ambigious as to order of these vtags.
We think it is this way around. If we are wrong, the order will need
to be changed. */
case SN_TO_GLOBAL:
*g_vtag = vtag_param->local_vtag;
*l_vtag = vtag_param->remote_vtag;
break;
case SN_TO_LOCAL:
*g_vtag = vtag_param->remote_vtag;
*l_vtag = vtag_param->local_vtag;
break;
}
return(1); /* found */
}
bytes_left -= param_size;
if (bytes_left < SN_MIN_PARAM_SIZE) return(0);
param = SN_SCTP_NEXTPARAM(param);
param_size = SCTP_SIZE32(ntohs(param->param_length));
if (++param_count > sysctl_param_proc_limit) {
SN_LOG(SN_LOG_EVENT,
logsctperror("Parameter parse limit exceeded (GetAsconfVtags)",
sm->sctp_hdr->v_tag, sysctl_param_proc_limit, direction));
return(0); /* not found limit exceeded*/
}
}
return(0); /* not found */
}
/** @ingroup packet_parser
* @brief AddGlobalIPAddresses from Init,InitAck,or AddIP packets
*
* AddGlobalIPAddresses scans an SCTP chunk (in sm) for Global IP addresses, and
* adds them.
*
* @param sm Pointer to sctp message information
* @param assoc Pointer to the association this SCTP Message belongs to
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
*
*/
static void
AddGlobalIPAddresses(struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc, int direction)
{
struct sctp_ipv4addr_param *ipv4_param;
struct sctp_paramhdr *param = NULL;
struct sctp_GlobalAddress *G_Addr;
struct in_addr g_addr = {0};
int bytes_left = 0;
int param_size;
int param_count, addr_param_count = 0;
switch(direction) {
case SN_TO_GLOBAL: /* does not contain global addresses */
g_addr = sm->ip_hdr->ip_dst;
bytes_left = 0; /* force exit */
break;
case SN_TO_LOCAL:
g_addr = sm->ip_hdr->ip_src;
param_count = 1;
switch(sm->msg) {
case SN_SCTP_INIT:
bytes_left = sm->chunk_length - sizeof(struct sctp_init_chunk);
param = (struct sctp_paramhdr *)((char *)sm->sctpchnk.Init + sizeof(struct sctp_init));
break;
case SN_SCTP_INITACK:
bytes_left = sm->chunk_length - sizeof(struct sctp_init_ack_chunk);
param = (struct sctp_paramhdr *)((char *)sm->sctpchnk.InitAck + sizeof(struct sctp_init_ack));
break;
case SN_SCTP_ASCONF:
bytes_left = sm->chunk_length;
param = sm->sctpchnk.Asconf;
break;
}
}
if (bytes_left >= SN_MIN_PARAM_SIZE)
param_size = SCTP_SIZE32(ntohs(param->param_length));
else
param_size = bytes_left+1; /* force skip loop */
if ((assoc->state == SN_ID) && ((sm->msg == SN_SCTP_INIT) || (bytes_left < SN_MIN_PARAM_SIZE))) {/* add pkt address */
G_Addr = (struct sctp_GlobalAddress *) sn_malloc(sizeof(struct sctp_GlobalAddress));
if (G_Addr == NULL) {/* out of resources */
SN_LOG(SN_LOG_EVENT,
logsctperror("AddGlobalIPAddress: No resources for adding global address - revert to no tracking",
sm->sctp_hdr->v_tag, 0, direction));
assoc->num_Gaddr = 0; /* don't track any more for this assoc*/
sysctl_track_global_addresses=0;
return;
}
G_Addr->g_addr = g_addr;
if (!Add_Global_Address_to_List(assoc, G_Addr))
SN_LOG(SN_LOG_EVENT,
logsctperror("AddGlobalIPAddress: Address already in list",
sm->sctp_hdr->v_tag, assoc->num_Gaddr, direction));
}
/* step through parameters */
while((bytes_left >= param_size) && (bytes_left >= sizeof(struct sctp_ipv4addr_param))) {
if (assoc->num_Gaddr >= sysctl_track_global_addresses) {
SN_LOG(SN_LOG_EVENT,
logsctperror("AddGlobalIPAddress: Maximum Number of addresses reached",
sm->sctp_hdr->v_tag, sysctl_track_global_addresses, direction));
return;
}
switch(ntohs(param->param_type)) {
case SCTP_ADD_IP_ADDRESS:
/* skip to address parameter - leave param_size so bytes left will be calculated properly*/
param = (struct sctp_paramhdr *) &((struct sctp_asconf_addrv4_param *) param)->addrp;
case SCTP_IPV4_ADDRESS:
ipv4_param = (struct sctp_ipv4addr_param *) param;
/* add addresses to association */
G_Addr = (struct sctp_GlobalAddress *) sn_malloc(sizeof(struct sctp_GlobalAddress));
if (G_Addr == NULL) {/* out of resources */
SN_LOG(SN_LOG_EVENT,
logsctperror("AddGlobalIPAddress: No resources for adding global address - revert to no tracking",
sm->sctp_hdr->v_tag, 0, direction));
assoc->num_Gaddr = 0; /* don't track any more for this assoc*/
sysctl_track_global_addresses=0;
return;
}
/* add address */
addr_param_count++;
if ((sm->msg == SN_SCTP_ASCONF) && (ipv4_param->addr == INADDR_ANY)) { /* use packet address */
G_Addr->g_addr = g_addr;
if (!Add_Global_Address_to_List(assoc, G_Addr))
SN_LOG(SN_LOG_EVENT,
logsctperror("AddGlobalIPAddress: Address already in list",
sm->sctp_hdr->v_tag, assoc->num_Gaddr, direction));
return; /*shouldn't be any other addresses if the zero address is given*/
} else {
G_Addr->g_addr.s_addr = ipv4_param->addr;
if (!Add_Global_Address_to_List(assoc, G_Addr))
SN_LOG(SN_LOG_EVENT,
logsctperror("AddGlobalIPAddress: Address already in list",
sm->sctp_hdr->v_tag, assoc->num_Gaddr, direction));
}
}
bytes_left -= param_size;
if (bytes_left < SN_MIN_PARAM_SIZE)
break;
param = SN_SCTP_NEXTPARAM(param);
param_size = SCTP_SIZE32(ntohs(param->param_length));
if (++param_count > sysctl_param_proc_limit) {
SN_LOG(SN_LOG_EVENT,
logsctperror("Parameter parse limit exceeded (AddGlobalIPAddress)",
sm->sctp_hdr->v_tag, sysctl_param_proc_limit, direction));
break; /* limit exceeded*/
}
}
if (addr_param_count == 0) {
SN_LOG(SN_LOG_DETAIL,
logsctperror("AddGlobalIPAddress: no address parameters to add",
sm->sctp_hdr->v_tag, assoc->num_Gaddr, direction));
}
}
/**
* @brief Add_Global_Address_to_List
*
* Adds a global IP address to an associations address list, if it is not
* already there. The first address added us usually the packet's address, and
* is most likely to be used, so it is added at the beginning. Subsequent
* addresses are added after this one.
*
* @param assoc Pointer to the association this SCTP Message belongs to
* @param G_addr Pointer to the global address to add
*
* @return 1 - success | 0 - fail
*/
static int Add_Global_Address_to_List(struct sctp_nat_assoc *assoc, struct sctp_GlobalAddress *G_addr)
{
struct sctp_GlobalAddress *iter_G_Addr = NULL, *first_G_Addr = NULL;
first_G_Addr = LIST_FIRST(&(assoc->Gaddr));
if (first_G_Addr == NULL) {
LIST_INSERT_HEAD(&(assoc->Gaddr), G_addr, list_Gaddr); /* add new address to beginning of list*/
} else {
LIST_FOREACH(iter_G_Addr, &(assoc->Gaddr), list_Gaddr) {
if (G_addr->g_addr.s_addr == iter_G_Addr->g_addr.s_addr)
return(0); /* already exists, so don't add */
}
LIST_INSERT_AFTER(first_G_Addr, G_addr, list_Gaddr); /* add address to end of list*/
}
assoc->num_Gaddr++;
return(1); /* success */
}
/** @ingroup packet_parser
* @brief RmGlobalIPAddresses from DelIP packets
*
* RmGlobalIPAddresses scans an ASCONF chunk for DelIP parameters to remove the
* given Global IP addresses from the association. It will not delete the
* the address if it is a list of one address.
*
*
* @param sm Pointer to sctp message information
* @param assoc Pointer to the association this SCTP Message belongs to
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
*
*/
static void
RmGlobalIPAddresses(struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc, int direction)
{
struct sctp_asconf_addrv4_param *asconf_ipv4_param;
struct sctp_paramhdr *param;
struct sctp_GlobalAddress *G_Addr, *G_Addr_tmp;
struct in_addr g_addr;
int bytes_left;
int param_size;
int param_count;
if(direction == SN_TO_GLOBAL)
g_addr = sm->ip_hdr->ip_dst;
else
g_addr = sm->ip_hdr->ip_src;
bytes_left = sm->chunk_length;
param_count = 1;
param = sm->sctpchnk.Asconf;
if (bytes_left >= SN_MIN_PARAM_SIZE) {
param_size = SCTP_SIZE32(ntohs(param->param_length));
} else {
SN_LOG(SN_LOG_EVENT,
logsctperror("RmGlobalIPAddress: truncated packet - cannot remove IP addresses",
sm->sctp_hdr->v_tag, sysctl_track_global_addresses, direction));
return;
}
/* step through Asconf parameters */
while((bytes_left >= param_size) && (bytes_left >= sizeof(struct sctp_ipv4addr_param))) {
if (ntohs(param->param_type) == SCTP_DEL_IP_ADDRESS) {
asconf_ipv4_param = (struct sctp_asconf_addrv4_param *) param;
if (asconf_ipv4_param->addrp.addr == INADDR_ANY) { /* remove all bar pkt address */
LIST_FOREACH_SAFE(G_Addr, &(assoc->Gaddr), list_Gaddr, G_Addr_tmp) {
if(G_Addr->g_addr.s_addr != sm->ip_hdr->ip_src.s_addr) {
if (assoc->num_Gaddr > 1) { /* only delete if more than one */
LIST_REMOVE(G_Addr, list_Gaddr);
sn_free(G_Addr);
assoc->num_Gaddr--;
} else {
SN_LOG(SN_LOG_EVENT,
logsctperror("RmGlobalIPAddress: Request to remove last IP address (didn't)",
sm->sctp_hdr->v_tag, assoc->num_Gaddr, direction));
}
}
}
return; /*shouldn't be any other addresses if the zero address is given*/
} else {
LIST_FOREACH_SAFE(G_Addr, &(assoc->Gaddr), list_Gaddr, G_Addr_tmp) {
if(G_Addr->g_addr.s_addr == asconf_ipv4_param->addrp.addr) {
if (assoc->num_Gaddr > 1) { /* only delete if more than one */
LIST_REMOVE(G_Addr, list_Gaddr);
sn_free(G_Addr);
assoc->num_Gaddr--;
break; /* Since add only adds new addresses, there should be no double entries */
} else {
SN_LOG(SN_LOG_EVENT,
logsctperror("RmGlobalIPAddress: Request to remove last IP address (didn't)",
sm->sctp_hdr->v_tag, assoc->num_Gaddr, direction));
}
}
}
}
}
bytes_left -= param_size;
if (bytes_left == 0) return;
else if (bytes_left < SN_MIN_PARAM_SIZE) {
SN_LOG(SN_LOG_EVENT,
logsctperror("RmGlobalIPAddress: truncated packet - may not have removed all IP addresses",
sm->sctp_hdr->v_tag, sysctl_track_global_addresses, direction));
return;
}
param = SN_SCTP_NEXTPARAM(param);
param_size = SCTP_SIZE32(ntohs(param->param_length));
if (++param_count > sysctl_param_proc_limit) {
SN_LOG(SN_LOG_EVENT,
logsctperror("Parameter parse limit exceeded (RmGlobalIPAddress)",
sm->sctp_hdr->v_tag, sysctl_param_proc_limit, direction));
return; /* limit exceeded*/
}
}
}
/** @ingroup packet_parser
* @brief Check that ASCONF was successful
*
* Each ASCONF configuration parameter carries a correlation ID which should be
* matched with an ASCONFack. This is difficult for a NAT, since every
* association could potentially have a number of outstanding ASCONF
* configuration parameters, which should only be activated on receipt of the
* ACK.
*
* Currently we only look for an ACK when the NAT is setting up a new
* association (ie AddIP for a connection that the NAT does not know about
* because the original Init went through a public interface or another NAT)
* Since there is currently no connection on this path, there should be no other
* ASCONF configuration parameters outstanding, so we presume that if there is
* an ACK that it is responding to the AddIP and activate the new association.
*
* @param la Pointer to the relevant libalias instance
* @param sm Pointer to sctp message information
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
*
* @return 1 - success | 0 - fail
*/
static int
IsASCONFack(struct libalias *la, struct sctp_nat_msg *sm, int direction)
{
struct sctp_paramhdr *param;
int bytes_left;
int param_size;
int param_count;
param_count = 1;
param = sm->sctpchnk.Asconf;
param_size = SCTP_SIZE32(ntohs(param->param_length));
if (param_size == 8)
return(1); /*success - default acknowledgement of everything */
bytes_left = sm->chunk_length;
if (bytes_left < param_size)
return(0); /* not found */
/* step through Asconf parameters */
while(bytes_left >= SN_ASCONFACK_PARAM_SIZE) {
if (ntohs(param->param_type) == SCTP_SUCCESS_REPORT)
return(1); /* success - but can't match correlation IDs - should only be one */
/* check others just in case */
bytes_left -= param_size;
if (bytes_left >= SN_MIN_PARAM_SIZE) {
param = SN_SCTP_NEXTPARAM(param);
} else {
return(0);
}
param_size = SCTP_SIZE32(ntohs(param->param_length));
if (bytes_left < param_size) return(0);
if (++param_count > sysctl_param_proc_limit) {
SN_LOG(SN_LOG_EVENT,
logsctperror("Parameter parse limit exceeded (IsASCONFack)",
sm->sctp_hdr->v_tag, sysctl_param_proc_limit, direction));
return(0); /* not found limit exceeded*/
}
}
return(0); /* not success */
}
/** @ingroup packet_parser
* @brief Check to see if ASCONF contains an Add IP or Del IP parameter
*
* IsADDorDEL scans an ASCONF packet to see if it contains an AddIP or DelIP
* parameter
*
* @param la Pointer to the relevant libalias instance
* @param sm Pointer to sctp message information
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
*
* @return SCTP_ADD_IP_ADDRESS | SCTP_DEL_IP_ADDRESS | 0 - fail
*/
static int
IsADDorDEL(struct libalias *la, struct sctp_nat_msg *sm, int direction)
{
struct sctp_paramhdr *param;
int bytes_left;
int param_size;
int param_count;
param_count = 1;
param = sm->sctpchnk.Asconf;
param_size = SCTP_SIZE32(ntohs(param->param_length));
bytes_left = sm->chunk_length;
if (bytes_left < param_size)
return(0); /* not found */
/* step through Asconf parameters */
while(bytes_left >= SN_ASCONFACK_PARAM_SIZE) {
if (ntohs(param->param_type) == SCTP_ADD_IP_ADDRESS)
return(SCTP_ADD_IP_ADDRESS);
else if (ntohs(param->param_type) == SCTP_DEL_IP_ADDRESS)
return(SCTP_DEL_IP_ADDRESS);
/* check others just in case */
bytes_left -= param_size;
if (bytes_left >= SN_MIN_PARAM_SIZE) {
param = SN_SCTP_NEXTPARAM(param);
} else {
return(0); /*Neither found */
}
param_size = SCTP_SIZE32(ntohs(param->param_length));
if (bytes_left < param_size) return(0);
if (++param_count > sysctl_param_proc_limit) {
SN_LOG(SN_LOG_EVENT,
logsctperror("Parameter parse limit exceeded IsADDorDEL)",
sm->sctp_hdr->v_tag, sysctl_param_proc_limit, direction));
return(0); /* not found limit exceeded*/
}
}
return(0); /*Neither found */
}
/* ----------------------------------------------------------------------
* STATE MACHINE CODE
* ----------------------------------------------------------------------
*/
/** @addtogroup state_machine
*
* The SCTP NAT State Machine functions will:
* - Process an already parsed packet
* - Use the existing NAT Hash Tables
* - Determine the next state for the association
* - Update the NAT Hash Tables and Timer Queues
* - Return the appropriate action to take with the packet
*/
/** @ingroup state_machine
* @brief Process SCTP message
*
* This function is the base state machine. It calls the processing engine for
* each state.
*
* @param la Pointer to the relevant libalias instance
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
* @param sm Pointer to sctp message information
* @param assoc Pointer to the association this SCTP Message belongs to
*
* @return SN_DROP_PKT | SN_NAT_PKT | SN_REPLY_ABORT | SN_REPLY_ERROR | SN_PROCESSING_ERROR
*/
static int
ProcessSctpMsg(struct libalias *la, int direction, struct sctp_nat_msg *sm, struct sctp_nat_assoc *assoc)
{
int rtnval;
switch (assoc->state) {
case SN_ID: /* Idle */
rtnval = ID_process(la, direction, assoc, sm);
if (rtnval != SN_NAT_PKT) {
assoc->state = SN_RM;/* Mark for removal*/
}
return(rtnval);
case SN_INi: /* Initialising - Init */
return(INi_process(la, direction, assoc, sm));
case SN_INa: /* Initialising - AddIP */
return(INa_process(la, direction, assoc, sm));
case SN_UP: /* Association UP */
return(UP_process(la, direction, assoc, sm));
case SN_CL: /* Association Closing */
return(CL_process(la, direction, assoc, sm));
}
return(SN_PROCESSING_ERROR);
}
/** @ingroup state_machine
* @brief Process SCTP message while in the Idle state
*
* This function looks for an Incoming INIT or AddIP message.
*
* All other SCTP messages are invalid when in SN_ID, and are dropped.
*
* @param la Pointer to the relevant libalias instance
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
* @param sm Pointer to sctp message information
* @param assoc Pointer to the association this SCTP Message belongs to
*
* @return SN_NAT_PKT | SN_DROP_PKT | SN_REPLY_ABORT | SN_REPLY_ERROR
*/
static int
ID_process(struct libalias *la, int direction, struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm)
{
switch(sm->msg) {
case SN_SCTP_ASCONF: /* a packet containing an ASCONF chunk with ADDIP */
if (!sysctl_accept_global_ootb_addip && (direction == SN_TO_LOCAL))
return(SN_DROP_PKT);
/* if this Asconf packet does not contain the Vtag parameters it is of no use in Idle state */
if (!GetAsconfVtags(la, sm, &(assoc->l_vtag), &(assoc->g_vtag), direction))
return(SN_DROP_PKT);
case SN_SCTP_INIT: /* a packet containing an INIT chunk or an ASCONF AddIP */
if (sysctl_track_global_addresses)
AddGlobalIPAddresses(sm, assoc, direction);
switch(direction){
case SN_TO_GLOBAL:
assoc->l_addr = sm->ip_hdr->ip_src;
assoc->a_addr = FindAliasAddress(la, assoc->l_addr);
assoc->l_port = sm->sctp_hdr->src_port;
assoc->g_port = sm->sctp_hdr->dest_port;
if(sm->msg == SN_SCTP_INIT)
assoc->g_vtag = sm->sctpchnk.Init->initiate_tag;
if (AddSctpAssocGlobal(la, assoc)) /* DB clash *///**** need to add dst address
return((sm->msg == SN_SCTP_INIT) ? SN_REPLY_ABORT : SN_REPLY_ERROR);
if(sm->msg == SN_SCTP_ASCONF) {
if (AddSctpAssocLocal(la, assoc, sm->ip_hdr->ip_dst)) /* DB clash */
return(SN_REPLY_ERROR);
assoc->TableRegister |= SN_WAIT_TOLOCAL; /* wait for tolocal ack */
}
break;
case SN_TO_LOCAL:
assoc->l_addr = FindSctpRedirectAddress(la, sm);
assoc->a_addr = sm->ip_hdr->ip_dst;
assoc->l_port = sm->sctp_hdr->dest_port;
assoc->g_port = sm->sctp_hdr->src_port;
if(sm->msg == SN_SCTP_INIT)
assoc->l_vtag = sm->sctpchnk.Init->initiate_tag;
if (AddSctpAssocLocal(la, assoc, sm->ip_hdr->ip_src)) /* DB clash */
return((sm->msg == SN_SCTP_INIT) ? SN_REPLY_ABORT : SN_REPLY_ERROR);
if(sm->msg == SN_SCTP_ASCONF) {
if (AddSctpAssocGlobal(la, assoc)) /* DB clash */ //**** need to add src address
return(SN_REPLY_ERROR);
assoc->TableRegister |= SN_WAIT_TOGLOBAL; /* wait for toglobal ack */
}
break;
}
assoc->state = (sm->msg == SN_SCTP_INIT) ? SN_INi : SN_INa;
assoc->exp = SN_I_T(la);
sctp_AddTimeOut(la,assoc);
return(SN_NAT_PKT);
default: /* Any other type of SCTP message is not valid in Idle */
return(SN_DROP_PKT);
}
return(SN_DROP_PKT);/* shouldn't get here very bad: log, drop and hope for the best */
}
/** @ingroup state_machine
* @brief Process SCTP message while waiting for an INIT-ACK message
*
* Only an INIT-ACK, resent INIT, or an ABORT SCTP packet are valid in this
* state, all other packets are dropped.
*
* @param la Pointer to the relevant libalias instance
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
* @param sm Pointer to sctp message information
* @param assoc Pointer to the association this SCTP Message belongs to
*
* @return SN_NAT_PKT | SN_DROP_PKT | SN_REPLY_ABORT
*/
static int
INi_process(struct libalias *la, int direction, struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm)
{
switch(sm->msg) {
case SN_SCTP_INIT: /* a packet containing a retransmitted INIT chunk */
sctp_ResetTimeOut(la, assoc, SN_I_T(la));
return(SN_NAT_PKT);
case SN_SCTP_INITACK: /* a packet containing an INIT-ACK chunk */
switch(direction){
case SN_TO_LOCAL:
if (assoc->num_Gaddr) /*If tracking global addresses for this association */
AddGlobalIPAddresses(sm, assoc, direction);
assoc->l_vtag = sm->sctpchnk.Init->initiate_tag;
if (AddSctpAssocLocal(la, assoc, sm->ip_hdr->ip_src)) { /* DB clash */
assoc->state = SN_RM;/* Mark for removal*/
return(SN_SEND_ABORT);
}
break;
case SN_TO_GLOBAL:
assoc->l_addr = sm->ip_hdr->ip_src; // Only if not set in Init! *
assoc->g_vtag = sm->sctpchnk.Init->initiate_tag;
if (AddSctpAssocGlobal(la, assoc)) { /* DB clash */
assoc->state = SN_RM;/* Mark for removal*/
return(SN_SEND_ABORT);
}
break;
}
assoc->state = SN_UP;/* association established for NAT */
sctp_ResetTimeOut(la,assoc, SN_U_T(la));
return(SN_NAT_PKT);
case SN_SCTP_ABORT: /* a packet containing an ABORT chunk */
assoc->state = SN_RM;/* Mark for removal*/
return(SN_NAT_PKT);
default:
return(SN_DROP_PKT);
}
return(SN_DROP_PKT);/* shouldn't get here very bad: log, drop and hope for the best */
}
/** @ingroup state_machine
* @brief Process SCTP message while waiting for an AddIp-ACK message
*
* Only an AddIP-ACK, resent AddIP, or an ABORT message are valid, all other
* SCTP packets are dropped
*
* @param la Pointer to the relevant libalias instance
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
* @param sm Pointer to sctp message information
* @param assoc Pointer to the association this SCTP Message belongs to
*
* @return SN_NAT_PKT | SN_DROP_PKT
*/
static int
INa_process(struct libalias *la, int direction,struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm)
{
switch(sm->msg) {
case SN_SCTP_ASCONF: /* a packet containing an ASCONF chunk*/
sctp_ResetTimeOut(la,assoc, SN_I_T(la));
return(SN_NAT_PKT);
case SN_SCTP_ASCONFACK: /* a packet containing an ASCONF chunk with a ADDIP-ACK */
switch(direction){
case SN_TO_LOCAL:
if (!(assoc->TableRegister & SN_WAIT_TOLOCAL)) /* wrong direction */
return(SN_DROP_PKT);
break;
case SN_TO_GLOBAL:
if (!(assoc->TableRegister & SN_WAIT_TOGLOBAL)) /* wrong direction */
return(SN_DROP_PKT);
}
if (IsASCONFack(la,sm,direction)) {
assoc->TableRegister &= SN_BOTH_TBL; /* remove wait flags */
assoc->state = SN_UP; /* association established for NAT */
sctp_ResetTimeOut(la,assoc, SN_U_T(la));
return(SN_NAT_PKT);
} else {
assoc->state = SN_RM;/* Mark for removal*/
return(SN_NAT_PKT);
}
case SN_SCTP_ABORT: /* a packet containing an ABORT chunk */
assoc->state = SN_RM;/* Mark for removal*/
return(SN_NAT_PKT);
default:
return(SN_DROP_PKT);
}
return(SN_DROP_PKT);/* shouldn't get here very bad: log, drop and hope for the best */
}
/** @ingroup state_machine
* @brief Process SCTP messages while association is UP redirecting packets
*
* While in the SN_UP state, all packets for the particular association
* are passed. Only a SHUT-ACK or an ABORT will cause a change of state.
*
* @param la Pointer to the relevant libalias instance
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
* @param sm Pointer to sctp message information
* @param assoc Pointer to the association this SCTP Message belongs to
*
* @return SN_NAT_PKT | SN_DROP_PKT
*/
static int
UP_process(struct libalias *la, int direction, struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm)
{
switch(sm->msg) {
case SN_SCTP_SHUTACK: /* a packet containing a SHUTDOWN-ACK chunk */
assoc->state = SN_CL;
sctp_ResetTimeOut(la,assoc, SN_C_T(la));
return(SN_NAT_PKT);
case SN_SCTP_ABORT: /* a packet containing an ABORT chunk */
assoc->state = SN_RM;/* Mark for removal*/
return(SN_NAT_PKT);
case SN_SCTP_ASCONF: /* a packet containing an ASCONF chunk*/
if ((direction == SN_TO_LOCAL) && assoc->num_Gaddr) /*If tracking global addresses for this association & from global side */
switch(IsADDorDEL(la,sm,direction)) {
case SCTP_ADD_IP_ADDRESS:
AddGlobalIPAddresses(sm, assoc, direction);
break;
case SCTP_DEL_IP_ADDRESS:
RmGlobalIPAddresses(sm, assoc, direction);
break;
} /* fall through to default */
default:
sctp_ResetTimeOut(la,assoc, SN_U_T(la));
return(SN_NAT_PKT); /* forward packet */
}
return(SN_DROP_PKT);/* shouldn't get here very bad: log, drop and hope for the best */
}
/** @ingroup state_machine
* @brief Process SCTP message while association is in the process of closing
*
* This function waits for a SHUT-COMP to close the association. Depending on
* the setting of sysctl_holddown_timer it may not remove the association
* immediately, but leave it up until SN_X_T(la). Only SHUT-COMP, SHUT-ACK, and
* ABORT packets are permitted in this state. All other packets are dropped.
*
* @param la Pointer to the relevant libalias instance
* @param direction SN_TO_LOCAL | SN_TO_GLOBAL
* @param sm Pointer to sctp message information
* @param assoc Pointer to the association this SCTP Message belongs to
*
* @return SN_NAT_PKT | SN_DROP_PKT
*/
static int
CL_process(struct libalias *la, int direction,struct sctp_nat_assoc *assoc, struct sctp_nat_msg *sm)
{
switch(sm->msg) {
case SN_SCTP_SHUTCOMP: /* a packet containing a SHUTDOWN-COMPLETE chunk */
assoc->state = SN_CL; /* Stay in Close state until timeout */
if (sysctl_holddown_timer > 0)
sctp_ResetTimeOut(la, assoc, SN_X_T(la));/* allow to stay open for Tbit packets*/
else
assoc->state = SN_RM;/* Mark for removal*/
return(SN_NAT_PKT);
case SN_SCTP_SHUTACK: /* a packet containing a SHUTDOWN-ACK chunk */
assoc->state = SN_CL; /* Stay in Close state until timeout */
sctp_ResetTimeOut(la, assoc, SN_C_T(la));
return(SN_NAT_PKT);
case SN_SCTP_ABORT: /* a packet containing an ABORT chunk */
assoc->state = SN_RM;/* Mark for removal*/
return(SN_NAT_PKT);
default:
return(SN_DROP_PKT);
}
return(SN_DROP_PKT);/* shouldn't get here very bad: log, drop and hope for the best */
}
/* ----------------------------------------------------------------------
* HASH TABLE CODE
* ----------------------------------------------------------------------
*/
/** @addtogroup Hash
*
* The Hash functions facilitate searching the NAT Hash Tables for associations
* as well as adding/removing associations from the table(s).
*/
/** @ingroup Hash
* @brief Find the SCTP association given the local address, port and vtag
*
* Searches the local look-up table for the association entry matching the
* provided local <address:ports:vtag> tuple
*
* @param la Pointer to the relevant libalias instance
* @param l_addr local address
* @param g_addr global address
* @param l_vtag local Vtag
* @param l_port local Port
* @param g_port global Port
*
* @return pointer to association or NULL
*/
static struct sctp_nat_assoc*
FindSctpLocal(struct libalias *la, struct in_addr l_addr, struct in_addr g_addr, uint32_t l_vtag, uint16_t l_port, uint16_t g_port)
{
u_int i;
struct sctp_nat_assoc *assoc = NULL;
struct sctp_GlobalAddress *G_Addr = NULL;
if (l_vtag != 0) { /* an init packet, vtag==0 */
i = SN_TABLE_HASH(l_vtag, l_port, la->sctpNatTableSize);
LIST_FOREACH(assoc, &la->sctpTableLocal[i], list_L) {
if ((assoc->l_vtag == l_vtag) && (assoc->l_port == l_port) && (assoc->g_port == g_port)\
&& (assoc->l_addr.s_addr == l_addr.s_addr)) {
if (assoc->num_Gaddr) {
LIST_FOREACH(G_Addr, &(assoc->Gaddr), list_Gaddr) {
if(G_Addr->g_addr.s_addr == g_addr.s_addr)
return(assoc);
}
} else {
return(assoc);
}
}
}
}
return(NULL);
}
/** @ingroup Hash
* @brief Check for Global Clash
*
* Searches the global look-up table for the association entry matching the
* provided global <(addresses):ports:vtag> tuple
*
* @param la Pointer to the relevant libalias instance
* @param Cassoc association being checked for a clash
*
* @return pointer to association or NULL
*/
static struct sctp_nat_assoc*
FindSctpGlobalClash(struct libalias *la, struct sctp_nat_assoc *Cassoc)
{
u_int i;
struct sctp_nat_assoc *assoc = NULL;
struct sctp_GlobalAddress *G_Addr = NULL;
struct sctp_GlobalAddress *G_AddrC = NULL;
if (Cassoc->g_vtag != 0) { /* an init packet, vtag==0 */
i = SN_TABLE_HASH(Cassoc->g_vtag, Cassoc->g_port, la->sctpNatTableSize);
LIST_FOREACH(assoc, &la->sctpTableGlobal[i], list_G) {
if ((assoc->g_vtag == Cassoc->g_vtag) && (assoc->g_port == Cassoc->g_port) && (assoc->l_port == Cassoc->l_port)) {
if (assoc->num_Gaddr) {
LIST_FOREACH(G_AddrC, &(Cassoc->Gaddr), list_Gaddr) {
LIST_FOREACH(G_Addr, &(assoc->Gaddr), list_Gaddr) {
if(G_Addr->g_addr.s_addr == G_AddrC->g_addr.s_addr)
return(assoc);
}
}
} else {
return(assoc);
}
}
}
}
return(NULL);
}
/** @ingroup Hash
* @brief Find the SCTP association given the global port and vtag
*
* Searches the global look-up table for the association entry matching the
* provided global <address:ports:vtag> tuple
*
* If all but the global address match it sets partial_match to 1 to indicate a
* partial match. If the NAT is tracking global IP addresses for this
* association, the NAT may respond with an ERRORM to request the missing
* address to be added.
*
* @param la Pointer to the relevant libalias instance
* @param g_addr global address
* @param g_vtag global vtag
* @param g_port global port
* @param l_port local port
*
* @return pointer to association or NULL
*/
static struct sctp_nat_assoc*
FindSctpGlobal(struct libalias *la, struct in_addr g_addr, uint32_t g_vtag, uint16_t g_port, uint16_t l_port, int *partial_match)
{
u_int i;
struct sctp_nat_assoc *assoc = NULL;
struct sctp_GlobalAddress *G_Addr = NULL;
*partial_match = 0;
if (g_vtag != 0) { /* an init packet, vtag==0 */
i = SN_TABLE_HASH(g_vtag, g_port, la->sctpNatTableSize);
LIST_FOREACH(assoc, &la->sctpTableGlobal[i], list_G) {
if ((assoc->g_vtag == g_vtag) && (assoc->g_port == g_port) && (assoc->l_port == l_port)) {
*partial_match = 1;
if (assoc->num_Gaddr) {
LIST_FOREACH(G_Addr, &(assoc->Gaddr), list_Gaddr) {
if(G_Addr->g_addr.s_addr == g_addr.s_addr)
return(assoc);
}
} else {
return(assoc);
}
}
}
}
return(NULL);
}
/** @ingroup Hash
* @brief Find the SCTP association for a T-Flag message (given the global port and local vtag)
*
* Searches the local look-up table for a unique association entry matching the
* provided global port and local vtag information
*
* @param la Pointer to the relevant libalias instance
* @param g_addr global address
* @param l_vtag local Vtag
* @param g_port global Port
* @param l_port local Port
*
* @return pointer to association or NULL
*/
static struct sctp_nat_assoc*
FindSctpLocalT(struct libalias *la, struct in_addr g_addr, uint32_t l_vtag, uint16_t g_port, uint16_t l_port)
{
u_int i;
struct sctp_nat_assoc *assoc = NULL, *lastmatch = NULL;
struct sctp_GlobalAddress *G_Addr = NULL;
int cnt = 0;
if (l_vtag != 0) { /* an init packet, vtag==0 */
i = SN_TABLE_HASH(l_vtag, g_port, la->sctpNatTableSize);
LIST_FOREACH(assoc, &la->sctpTableGlobal[i], list_G) {
if ((assoc->g_vtag == l_vtag) && (assoc->g_port == g_port) && (assoc->l_port == l_port)) {
if (assoc->num_Gaddr) {
LIST_FOREACH(G_Addr, &(assoc->Gaddr), list_Gaddr) {
if(G_Addr->g_addr.s_addr == G_Addr->g_addr.s_addr)
return(assoc); /* full match */
}
} else {
if (++cnt > 1) return(NULL);
lastmatch = assoc;
}
}
}
}
/* If there is more than one match we do not know which local address to send to */
return( cnt ? lastmatch : NULL );
}
/** @ingroup Hash
* @brief Find the SCTP association for a T-Flag message (given the local port and global vtag)
*
* Searches the global look-up table for a unique association entry matching the
* provided local port and global vtag information
*
* @param la Pointer to the relevant libalias instance
* @param g_addr global address
* @param g_vtag global vtag
* @param l_port local port
* @param g_port global port
*
* @return pointer to association or NULL
*/
static struct sctp_nat_assoc*
FindSctpGlobalT(struct libalias *la, struct in_addr g_addr, uint32_t g_vtag, uint16_t l_port, uint16_t g_port)
{
u_int i;
struct sctp_nat_assoc *assoc = NULL;
struct sctp_GlobalAddress *G_Addr = NULL;
if (g_vtag != 0) { /* an init packet, vtag==0 */
i = SN_TABLE_HASH(g_vtag, l_port, la->sctpNatTableSize);
LIST_FOREACH(assoc, &la->sctpTableLocal[i], list_L) {
if ((assoc->l_vtag == g_vtag) && (assoc->l_port == l_port) && (assoc->g_port == g_port)) {
if (assoc->num_Gaddr) {
LIST_FOREACH(G_Addr, &(assoc->Gaddr), list_Gaddr) {
if(G_Addr->g_addr.s_addr == g_addr.s_addr)
return(assoc);
}
} else {
return(assoc);
}
}
}
}
return(NULL);
}
/** @ingroup Hash
* @brief Add the sctp association information to the local look up table
*
* Searches the local look-up table for an existing association with the same
* details. If a match exists and is ONLY in the local look-up table then this
* is a repeated INIT packet, we need to remove this association from the
* look-up table and add the new association
*
* The new association is added to the head of the list and state is updated
*
* @param la Pointer to the relevant libalias instance
* @param assoc pointer to sctp association
* @param g_addr global address
*
* @return SN_ADD_OK | SN_ADD_CLASH
*/
static int
AddSctpAssocLocal(struct libalias *la, struct sctp_nat_assoc *assoc, struct in_addr g_addr)
{
struct sctp_nat_assoc *found;
LIBALIAS_LOCK_ASSERT(la);
found = FindSctpLocal(la, assoc->l_addr, g_addr, assoc->l_vtag, assoc->l_port, assoc->g_port);
/*
* Note that if a different global address initiated this Init,
* ie it wasn't resent as presumed:
* - the local receiver if receiving it for the first time will establish
* an association with the new global host
* - if receiving an init from a different global address after sending a
* lost initack it will send an initack to the new global host, the first
* association attempt will then be blocked if retried.
*/
if (found != NULL) {
if ((found->TableRegister == SN_LOCAL_TBL) && (found->g_port == assoc->g_port)) { /* resent message */
RmSctpAssoc(la, found);
sctp_RmTimeOut(la, found);
freeGlobalAddressList(found);
sn_free(found);
} else
return(SN_ADD_CLASH);
}
LIST_INSERT_HEAD(&la->sctpTableLocal[SN_TABLE_HASH(assoc->l_vtag, assoc->l_port, la->sctpNatTableSize)],
assoc, list_L);
assoc->TableRegister |= SN_LOCAL_TBL;
la->sctpLinkCount++; //increment link count
if (assoc->TableRegister == SN_BOTH_TBL) {
/* libalias log -- controlled by libalias */
if (la->packetAliasMode & PKT_ALIAS_LOG)
SctpShowAliasStats(la);
SN_LOG(SN_LOG_INFO, logsctpassoc(assoc, "^"));
}
return(SN_ADD_OK);
}
/** @ingroup Hash
* @brief Add the sctp association information to the global look up table
*
* Searches the global look-up table for an existing association with the same
* details. If a match exists and is ONLY in the global look-up table then this
* is a repeated INIT packet, we need to remove this association from the
* look-up table and add the new association
*
* The new association is added to the head of the list and state is updated
*
* @param la Pointer to the relevant libalias instance
* @param assoc pointer to sctp association
*
* @return SN_ADD_OK | SN_ADD_CLASH
*/
static int
AddSctpAssocGlobal(struct libalias *la, struct sctp_nat_assoc *assoc)
{
struct sctp_nat_assoc *found;
LIBALIAS_LOCK_ASSERT(la);
found = FindSctpGlobalClash(la, assoc);
if (found != NULL) {
if ((found->TableRegister == SN_GLOBAL_TBL) && \
(found->l_addr.s_addr == assoc->l_addr.s_addr) && (found->l_port == assoc->l_port)) { /* resent message */
RmSctpAssoc(la, found);
sctp_RmTimeOut(la, found);
freeGlobalAddressList(found);
sn_free(found);
} else
return(SN_ADD_CLASH);
}
LIST_INSERT_HEAD(&la->sctpTableGlobal[SN_TABLE_HASH(assoc->g_vtag, assoc->g_port, la->sctpNatTableSize)],
assoc, list_G);
assoc->TableRegister |= SN_GLOBAL_TBL;
la->sctpLinkCount++; //increment link count
if (assoc->TableRegister == SN_BOTH_TBL) {
/* libalias log -- controlled by libalias */
if (la->packetAliasMode & PKT_ALIAS_LOG)
SctpShowAliasStats(la);
SN_LOG(SN_LOG_INFO, logsctpassoc(assoc, "^"));
}
return(SN_ADD_OK);
}
/** @ingroup Hash
* @brief Remove the sctp association information from the look up table
*
* For each of the two (local/global) look-up tables, remove the association
* from that table IF it has been registered in that table.
*
* NOTE: The calling code is responsible for freeing memory allocated to the
* association structure itself
*
* NOTE: The association is NOT removed from the timer queue
*
* @param la Pointer to the relevant libalias instance
* @param assoc pointer to sctp association
*/
static void
RmSctpAssoc(struct libalias *la, struct sctp_nat_assoc *assoc)
{
// struct sctp_nat_assoc *found;
if (assoc == NULL) {
/* very bad, log and die*/
SN_LOG(SN_LOG_LOW,
logsctperror("ERROR: alias_sctp:RmSctpAssoc(NULL)\n", 0, 0, SN_TO_NODIR));
return;
}
/* log if association is fully up and now closing */
if (assoc->TableRegister == SN_BOTH_TBL) {
SN_LOG(SN_LOG_INFO, logsctpassoc(assoc, "$"));
}
LIBALIAS_LOCK_ASSERT(la);
if (assoc->TableRegister & SN_LOCAL_TBL) {
assoc->TableRegister ^= SN_LOCAL_TBL;
la->sctpLinkCount--; //decrement link count
LIST_REMOVE(assoc, list_L);
}
if (assoc->TableRegister & SN_GLOBAL_TBL) {
assoc->TableRegister ^= SN_GLOBAL_TBL;
la->sctpLinkCount--; //decrement link count
LIST_REMOVE(assoc, list_G);
}
// sn_free(assoc); //Don't remove now, remove if needed later
/* libalias logging -- controlled by libalias log definition */
if (la->packetAliasMode & PKT_ALIAS_LOG)
SctpShowAliasStats(la);
}
/**
* @ingroup Hash
* @brief free the Global Address List memory
*
* freeGlobalAddressList deletes all global IP addresses in an associations
* global IP address list.
*
* @param assoc
*/
static void freeGlobalAddressList(struct sctp_nat_assoc *assoc)
{
struct sctp_GlobalAddress *gaddr1=NULL,*gaddr2=NULL;
/*free global address list*/
gaddr1 = LIST_FIRST(&(assoc->Gaddr));
while (gaddr1 != NULL) {
gaddr2 = LIST_NEXT(gaddr1, list_Gaddr);
sn_free(gaddr1);
gaddr1 = gaddr2;
}
}
/* ----------------------------------------------------------------------
* TIMER QUEUE CODE
* ----------------------------------------------------------------------
*/
/** @addtogroup Timer
*
* The timer queue management functions are designed to operate efficiently with
* a minimum of interaction with the queues.
*
* Once a timeout is set in the queue it will not be altered in the queue unless
* it has to be changed to a shorter time (usually only for aborts and closing).
* On a queue timeout, the real expiry time is checked, and if not leq than the
* timeout it is requeued (O(1)) at its later time. This is especially important
* for normal packets sent during an association. When a timer expires, it is
* updated to its new expiration time if necessary, or processed as a
* timeout. This means that while in UP state, the timing queue is only altered
* every U_T (every few minutes) for a particular association.
*/
/** @ingroup Timer
* @brief Add an association timeout to the timer queue
*
* Determine the location in the queue to add the timeout and insert the
* association into the list at that queue position
*
* @param la
* @param assoc
*/
static void
sctp_AddTimeOut(struct libalias *la, struct sctp_nat_assoc *assoc)
{
int add_loc;
LIBALIAS_LOCK_ASSERT(la);
add_loc = assoc->exp - la->sctpNatTimer.loc_time + la->sctpNatTimer.cur_loc;
if (add_loc >= SN_TIMER_QUEUE_SIZE)
add_loc -= SN_TIMER_QUEUE_SIZE;
LIST_INSERT_HEAD(&la->sctpNatTimer.TimerQ[add_loc], assoc, timer_Q);
assoc->exp_loc = add_loc;
}
/** @ingroup Timer
* @brief Remove an association from timer queue
*
* This is an O(1) operation to remove the association pointer from its
* current position in the timer queue
*
* @param la Pointer to the relevant libalias instance
* @param assoc pointer to sctp association
*/
static void
sctp_RmTimeOut(struct libalias *la, struct sctp_nat_assoc *assoc)
{
LIBALIAS_LOCK_ASSERT(la);
LIST_REMOVE(assoc, timer_Q);/* Note this is O(1) */
}
/** @ingroup Timer
* @brief Reset timer in timer queue
*
* Reset the actual timeout for the specified association. If it is earlier than
* the existing timeout, then remove and re-install the association into the
* queue
*
* @param la Pointer to the relevant libalias instance
* @param assoc pointer to sctp association
* @param newexp New expiration time
*/
static void
sctp_ResetTimeOut(struct libalias *la, struct sctp_nat_assoc *assoc, int newexp)
{
if (newexp < assoc->exp) {
sctp_RmTimeOut(la, assoc);
assoc->exp = newexp;
sctp_AddTimeOut(la, assoc);
} else {
assoc->exp = newexp;
}
}
/** @ingroup Timer
* @brief Check timer Q against current time
*
* Loop through each entry in the timer queue since the last time we processed
* the timer queue until now (the current time). For each association in the
* event list, we remove it from that position in the timer queue and check if
* it has really expired. If so we:
* - Log the timer expiry
* - Remove the association from the NAT tables
* - Release the memory used by the association
*
* If the timer hasn't really expired we place the association into its new
* correct position in the timer queue.
*
* @param la Pointer to the relevant libalias instance
*/
void
sctp_CheckTimers(struct libalias *la)
{
struct sctp_nat_assoc *assoc;
LIBALIAS_LOCK_ASSERT(la);
while(la->timeStamp >= la->sctpNatTimer.loc_time) {
while (!LIST_EMPTY(&la->sctpNatTimer.TimerQ[la->sctpNatTimer.cur_loc])) {
assoc = LIST_FIRST(&la->sctpNatTimer.TimerQ[la->sctpNatTimer.cur_loc]);
//SLIST_REMOVE_HEAD(&la->sctpNatTimer.TimerQ[la->sctpNatTimer.cur_loc], timer_Q);
LIST_REMOVE(assoc, timer_Q);
if (la->timeStamp >= assoc->exp) { /* state expired */
SN_LOG(((assoc->state == SN_CL)?(SN_LOG_DEBUG):(SN_LOG_INFO)),
logsctperror("Timer Expired", assoc->g_vtag, assoc->state, SN_TO_NODIR));
RmSctpAssoc(la, assoc);
freeGlobalAddressList(assoc);
sn_free(assoc);
} else {/* state not expired, reschedule timer*/
sctp_AddTimeOut(la, assoc);
}
}
/* Goto next location in the timer queue*/
++la->sctpNatTimer.loc_time;
if (++la->sctpNatTimer.cur_loc >= SN_TIMER_QUEUE_SIZE)
la->sctpNatTimer.cur_loc = 0;
}
}
/* ----------------------------------------------------------------------
* LOGGING CODE
* ----------------------------------------------------------------------
*/
/** @addtogroup Logging
*
* The logging functions provide logging of different items ranging from logging
* a simple message, through logging an association details to logging the
* current state of the NAT tables
*/
/** @ingroup Logging
* @brief Log sctp nat errors
*
* @param errormsg Error message to be logged
* @param vtag Current Vtag
* @param error Error number
* @param direction Direction of packet
*/
static void
logsctperror(char* errormsg, uint32_t vtag, int error, int direction)
{
char dir;
switch(direction) {
case SN_TO_LOCAL:
dir = 'L';
break;
case SN_TO_GLOBAL:
dir = 'G';
break;
default:
dir = '*';
break;
}
SctpAliasLog("->%c %s (vt=%u) %d\n", dir, errormsg, ntohl(vtag), error);
}
/** @ingroup Logging
* @brief Log what the parser parsed
*
* @param direction Direction of packet
* @param sm Pointer to sctp message information
*/
static void
logsctpparse(int direction, struct sctp_nat_msg *sm)
{
char *ploc, *pstate;
switch(direction) {
case SN_TO_LOCAL:
ploc = "TO_LOCAL -";
break;
case SN_TO_GLOBAL:
ploc = "TO_GLOBAL -";
break;
default:
ploc = "";
}
switch(sm->msg) {
case SN_SCTP_INIT:
pstate = "Init";
break;
case SN_SCTP_INITACK:
pstate = "InitAck";
break;
case SN_SCTP_ABORT:
pstate = "Abort";
break;
case SN_SCTP_SHUTACK:
pstate = "ShutAck";
break;
case SN_SCTP_SHUTCOMP:
pstate = "ShutComp";
break;
case SN_SCTP_ASCONF:
pstate = "Asconf";
break;
case SN_SCTP_ASCONFACK:
pstate = "AsconfAck";
break;
case SN_SCTP_OTHER:
pstate = "Other";
break;
default:
pstate = "***ERROR***";
break;
}
SctpAliasLog("Parsed: %s %s\n", ploc, pstate);
}
/** @ingroup Logging
* @brief Log an SCTP association's details
*
* @param assoc pointer to sctp association
* @param s Character that indicates the state of processing for this packet
*/
static void logsctpassoc(struct sctp_nat_assoc *assoc, char* s)
{
struct sctp_GlobalAddress *G_Addr = NULL;
char *sp;
switch(assoc->state) {
case SN_ID:
sp = "ID ";
break;
case SN_INi:
sp = "INi ";
break;
case SN_INa:
sp = "INa ";
break;
case SN_UP:
sp = "UP ";
break;
case SN_CL:
sp = "CL ";
break;
case SN_RM:
sp = "RM ";
break;
default:
sp = "***ERROR***";
break;
}
SctpAliasLog("%sAssoc: %s exp=%u la=%s lv=%u lp=%u gv=%u gp=%u tbl=%d\n",
s, sp, assoc->exp, inet_ntoa(assoc->l_addr), ntohl(assoc->l_vtag),
ntohs(assoc->l_port), ntohl(assoc->g_vtag), ntohs(assoc->g_port),
assoc->TableRegister);
/* list global addresses */
LIST_FOREACH(G_Addr, &(assoc->Gaddr), list_Gaddr) {
SctpAliasLog("\t\tga=%s\n",inet_ntoa(G_Addr->g_addr));
}
}
/** @ingroup Logging
* @brief Output Global table to log
*
* @param la Pointer to the relevant libalias instance
*/
static void logSctpGlobal(struct libalias *la)
{
u_int i;
struct sctp_nat_assoc *assoc = NULL;
SctpAliasLog("G->\n");
for (i=0; i < la->sctpNatTableSize; i++) {
LIST_FOREACH(assoc, &la->sctpTableGlobal[i], list_G) {
logsctpassoc(assoc, " ");
}
}
}
/** @ingroup Logging
* @brief Output Local table to log
*
* @param la Pointer to the relevant libalias instance
*/
static void logSctpLocal(struct libalias *la)
{
u_int i;
struct sctp_nat_assoc *assoc = NULL;
SctpAliasLog("L->\n");
for (i=0; i < la->sctpNatTableSize; i++) {
LIST_FOREACH(assoc, &la->sctpTableLocal[i], list_L) {
logsctpassoc(assoc, " ");
}
}
}
/** @ingroup Logging
* @brief Output timer queue to log
*
* @param la Pointer to the relevant libalias instance
*/
static void logTimerQ(struct libalias *la)
{
static char buf[50];
u_int i;
struct sctp_nat_assoc *assoc = NULL;
SctpAliasLog("t->\n");
for (i=0; i < SN_TIMER_QUEUE_SIZE; i++) {
LIST_FOREACH(assoc, &la->sctpNatTimer.TimerQ[i], timer_Q) {
snprintf(buf, 50, " l=%u ",i);
//SctpAliasLog(la->logDesc," l=%d ",i);
logsctpassoc(assoc, buf);
}
}
}
/** @ingroup Logging
* @brief Sctp NAT logging function
*
* This function is based on a similar function in alias_db.c
*
* @param str/stream logging descriptor
* @param format printf type string
*/
#ifdef _KERNEL
static void
SctpAliasLog(const char *format, ...)
{
char buffer[LIBALIAS_BUF_SIZE];
va_list ap;
va_start(ap, format);
vsnprintf(buffer, LIBALIAS_BUF_SIZE, format, ap);
va_end(ap);
log(LOG_SECURITY | LOG_INFO,
"alias_sctp: %s", buffer);
}
#else
static void
SctpAliasLog(FILE *stream, const char *format, ...)
{
va_list ap;
va_start(ap, format);
vfprintf(stream, format, ap);
va_end(ap);
fflush(stream);
}
#endif