/*- * SPDX-License-Identifier: BSD-2-Clause * * 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 */ #ifdef _KERNEL #include #include #include #include #include #include #include #include #include #include #include #include #else #include "alias_sctp.h" #include #include "alias.h" #include "alias_local.h" #include #include #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 static 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) mallocarray((n), (x), M_SCTPNAT, M_NOWAIT|M_ZERO) #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) (LibAliasTime + sysctl_init_timer) /**< INIT State expiration time in seconds */ #define SN_U_T(la) (LibAliasTime + sysctl_up_timer) /**< UP State expiration time in seconds */ #define SN_C_T(la) (LibAliasTime + sysctl_shutdown_timer) /**< CL State expiration time in seconds */ #define SN_X_T(la) (LibAliasTime + 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; /** 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); static SYSCTL_NODE(_net_inet_ip_alias, OID_AUTO, sctp, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL, "SCTP NAT"); SYSCTL_PROC(_net_inet_ip_alias_sctp, OID_AUTO, log_level, CTLTYPE_UINT | CTLFLAG_RW | CTLFLAG_NEEDGIANT, &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 | CTLFLAG_NEEDGIANT, &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 | CTLFLAG_NEEDGIANT, &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 | CTLFLAG_NEEDGIANT, &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 | CTLFLAG_NEEDGIANT, &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 | CTLFLAG_NEEDGIANT, &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 | CTLFLAG_NEEDGIANT, &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 | CTLFLAG_NEEDGIANT, &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 | CTLFLAG_NEEDGIANT, &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 | CTLFLAG_NEEDGIANT, &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 | CTLFLAG_NEEDGIANT, &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 | CTLFLAG_NEEDGIANT, &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); level = (level > SN_LOG_DEBUG_MAX) ? (SN_LOG_DEBUG_MAX) : (level); level = (level < SN_LOG_LOW) ? (SN_LOG_LOW) : (level); sysctl_log_level = 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; /* LibAliasTime is not set yet */ #else la->sctpNatTimer.loc_time=LibAliasTime; #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, * this is a fragmented packet, and we have a valid assoc. */ if ((assoc != NULL) && (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]; char addrbuf[INET_ADDRSTRLEN]; 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_r(ip->ip_dst, INET_NTOA_BUF(addrbuf)), 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 */ sm->msg = SN_SCTP_OTHER;/* Initialise to largest value*/ sm->chunk_length = 0; /* only care about length for key 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 */ 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); } /* Initialize association - sn_malloc initializes 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); } /* Initialize association - sn_malloc initializes 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; /* FALLTHROUGH */ 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); /* FALLTHROUGH */ 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 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 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.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(LibAliasTime >= 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 (LibAliasTime >= 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; char addrbuf[INET_ADDRSTRLEN]; 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_r(assoc->l_addr, addrbuf), 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_r(G_Addr->g_addr, addrbuf)); } } /** @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