#include <machine/stdarg.h>
#include <sys/param.h>
#include <sys/gsb_crc32.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/module.h>
#include <sys/syslog.h>
#include <netinet/libalias/alias_sctp.h>
#include <netinet/libalias/alias.h>
#include <netinet/libalias/alias_local.h>
#include <netinet/sctp_crc32.h>
#include <machine/in_cksum.h>

Include dependency graph for alias_sctp.c:

Macros
#define	SN_SCTP_FIRSTCHUNK(sctphead) (struct sctp_chunkhdr )(((char )sctphead) + sizeof(struct sctphdr))

#define	SN_SCTP_NEXTCHUNK(chunkhead) (struct sctp_chunkhdr )(((char )chunkhead) + SCTP_SIZE32(ntohs(chunkhead->chunk_length)))

#define	SN_SCTP_NEXTPARAM(param) (struct sctp_paramhdr )(((char )param) + SCTP_SIZE32(ntohs(param->param_length)))

#define	SN_MIN_CHUNK_SIZE 4

#define	SN_MIN_PARAM_SIZE 4

#define	SN_VTAG_PARAM_SIZE 12

#define	SN_ASCONFACK_PARAM_SIZE 8

#define	SN_PARSE_OK 0

#define	SN_PARSE_ERROR_IPSHL 1

#define	SN_PARSE_ERROR_AS_MALLOC 2

#define	SN_PARSE_ERROR_CHHL 3

#define	SN_PARSE_ERROR_DIR 4

#define	SN_PARSE_ERROR_VTAG 5

#define	SN_PARSE_ERROR_CHUNK 6

#define	SN_PARSE_ERROR_PORT 7

#define	SN_PARSE_ERROR_LOOKUP 8

#define	SN_PARSE_ERROR_PARTIALLOOKUP 9

#define	SN_PARSE_ERROR_LOOKUP_ABORT 10

#define	SN_SCTP_ABORT 0x0000

#define	SN_SCTP_INIT 0x0001

#define	SN_SCTP_INITACK 0x0002

#define	SN_SCTP_SHUTCOMP 0x0010

#define	SN_SCTP_SHUTACK 0x0020

#define	SN_SCTP_ASCONF 0x0100

#define	SN_SCTP_ASCONFACK 0x0200

#define	SN_SCTP_OTHER 0xFFFF

#define	SN_ID 0x0000

#define	SN_INi 0x0010

#define	SN_INa 0x0020

#define	SN_UP 0x0100

#define	SN_CL 0x1000

#define	SN_RM 0x2000

#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; }

#define	SN_MIN_HASH_SIZE 101

#define	SN_MAX_HASH_SIZE 1000001

#define	SN_DEFAULT_HASH_SIZE 2003

#define	SN_LOCAL_TBL 0x01

#define	SN_GLOBAL_TBL 0x02

#define	SN_BOTH_TBL 0x03

#define	SN_WAIT_TOLOCAL 0x10

#define	SN_WAIT_TOGLOBAL 0x20

#define	SN_NULL_TBL 0x00

#define	SN_MAX_GLOBAL_ADDRESSES 100

#define	SN_ADD_OK 0

#define	SN_ADD_CLASH 1

#define	SN_TABLE_HASH(vtag, port, size) (((u_int) vtag + (u_int) port) % (u_int) size)

#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)

#define	SN_U_T(la) (LibAliasTime + sysctl_up_timer)

#define	SN_C_T(la) (LibAliasTime + sysctl_shutdown_timer)

#define	SN_X_T(la) (LibAliasTime + sysctl_holddown_timer)

#define	SN_NO_ERROR_ON_OOTB 0

#define	SN_LOCAL_ERROR_ON_OOTB 1

#define	SN_LOCALandPARTIAL_ERROR_ON_OOTB 2

#define	SN_ERROR_ON_OOTB 3

#define	SCTP_MIDDLEBOX_FLAG 0x02

#define	SCTP_NAT_TABLE_COLLISION 0x00b0

#define	SCTP_MISSING_NAT 0x00b1

#define	SCTP_VTAG_PARAM 0xC007

Functions
static int	sctp_PktParser (struct libalias la, int direction, struct ip pip, struct sctp_nat_msg sm, struct sctp_nat_assoc *passoc)
	Parses SCTP packets for the key SCTP chunk that will be processed. More...

static int	GetAsconfVtags (struct libalias la, struct sctp_nat_msg sm, uint32_t l_vtag, uint32_t g_vtag, int direction)
	Extract Vtags from Asconf Chunk. More...

static int	IsASCONFack (struct libalias la, struct sctp_nat_msg sm, int direction)
	Check that ASCONF was successful. More...

static void	AddGlobalIPAddresses (struct sctp_nat_msg sm, struct sctp_nat_assoc assoc, int direction)
	AddGlobalIPAddresses from Init,InitAck,or AddIP packets. More...

static int	Add_Global_Address_to_List (struct sctp_nat_assoc assoc, struct sctp_GlobalAddress G_addr)
	Add_Global_Address_to_List. More...

static void	RmGlobalIPAddresses (struct sctp_nat_msg sm, struct sctp_nat_assoc assoc, int direction)
	RmGlobalIPAddresses from DelIP packets. More...

static int	IsADDorDEL (struct libalias la, struct sctp_nat_msg sm, int direction)
	Check to see if ASCONF contains an Add IP or Del IP parameter. More...

static int	ProcessSctpMsg (struct libalias la, int direction, struct sctp_nat_msg sm, struct sctp_nat_assoc *assoc)
	Process SCTP message. More...

static int	ID_process (struct libalias la, int direction, struct sctp_nat_assoc assoc, struct sctp_nat_msg *sm)
	Process SCTP message while in the Idle state. More...

static int	INi_process (struct libalias la, int direction, struct sctp_nat_assoc assoc, struct sctp_nat_msg *sm)
	Process SCTP message while waiting for an INIT-ACK message. More...

static int	INa_process (struct libalias la, int direction, struct sctp_nat_assoc assoc, struct sctp_nat_msg *sm)
	Process SCTP message while waiting for an AddIp-ACK message. More...

static int	UP_process (struct libalias la, int direction, struct sctp_nat_assoc assoc, struct sctp_nat_msg *sm)
	Process SCTP messages while association is UP redirecting packets. More...

static int	CL_process (struct libalias la, int direction, struct sctp_nat_assoc assoc, struct sctp_nat_msg *sm)
	Process SCTP message while association is in the process of closing. More...

static void	TxAbortErrorM (struct libalias la, struct sctp_nat_msg sm, struct sctp_nat_assoc *assoc, int sndrply, int direction)

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)
	Find the SCTP association given the local address, port and vtag. More...

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)
	Find the SCTP association given the global port and vtag. More...

static struct sctp_nat_assoc *	FindSctpGlobalClash (struct libalias la, struct sctp_nat_assoc Cassoc)
	Check for Global Clash. More...

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)
	Find the SCTP association for a T-Flag message (given the global port and local vtag) More...

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)
	Find the SCTP association for a T-Flag message (given the local port and global vtag) More...

static int	AddSctpAssocLocal (struct libalias la, struct sctp_nat_assoc assoc, struct in_addr g_addr)
	Add the sctp association information to the local look up table. More...

static int	AddSctpAssocGlobal (struct libalias la, struct sctp_nat_assoc assoc)
	Add the sctp association information to the global look up table. More...

static void	RmSctpAssoc (struct libalias la, struct sctp_nat_assoc assoc)
	Remove the sctp association information from the look up table. More...

static void	freeGlobalAddressList (struct sctp_nat_assoc *assoc)
	free the Global Address List memory More...

static void	sctp_AddTimeOut (struct libalias la, struct sctp_nat_assoc assoc)
	Add an association timeout to the timer queue. More...

static void	sctp_RmTimeOut (struct libalias la, struct sctp_nat_assoc assoc)
	Remove an association from timer queue. More...

static void	sctp_ResetTimeOut (struct libalias la, struct sctp_nat_assoc assoc, int newexp)
	Reset timer in timer queue. More...

void	sctp_CheckTimers (struct libalias *la)
	Check timer Q against current time. More...

static void	logsctperror (char *errormsg, uint32_t vtag, int error, int direction)
	Log sctp nat errors. More...

static void	logsctpparse (int direction, struct sctp_nat_msg *sm)
	Log what the parser parsed. More...

static void	logsctpassoc (struct sctp_nat_assoc assoc, char s)
	Log an SCTP association's details. More...

static void	logTimerQ (struct libalias *la)
	Output timer queue to log. More...

static void	logSctpGlobal (struct libalias *la)
	Output Global table to log. More...

static void	logSctpLocal (struct libalias *la)
	Output Local table to log. More...

static void	SctpAliasLog (const char *format,...)
	Sctp NAT logging function. More...

void	SctpShowAliasStats (struct libalias *la)
	Log current statistics for the libalias instance. More...

static	MALLOC_DEFINE (M_SCTPNAT, "sctpnat", "sctp nat dbs")

int	sysctl_chg_loglevel (SYSCTL_HANDLER_ARGS)
	sysctl callback for changing net.inet.ip.fw.sctp.log_level More...

int	sysctl_chg_timer (SYSCTL_HANDLER_ARGS)
	sysctl callback for changing net.inet.ip.fw.sctp.(init_timer\|up_timer\|shutdown_timer) More...

int	sysctl_chg_hashtable_size (SYSCTL_HANDLER_ARGS)
	sysctl callback for changing net.inet.ip.alias.sctp.hashtable_size More...

int	sysctl_chg_error_on_ootb (SYSCTL_HANDLER_ARGS)
	sysctl callback for changing net.inet.ip.alias.sctp.error_on_ootb More...

int	sysctl_chg_accept_global_ootb_addip (SYSCTL_HANDLER_ARGS)
	sysctl callback for changing net.inet.ip.alias.sctp.accept_global_ootb_addip More...

int	sysctl_chg_initialising_chunk_proc_limit (SYSCTL_HANDLER_ARGS)
	sysctl callback for changing net.inet.ip.alias.sctp.initialising_chunk_proc_limit More...

int	sysctl_chg_chunk_proc_limit (SYSCTL_HANDLER_ARGS)
	sysctl callback for changing net.inet.ip.alias.sctp.chunk_proc_limit More...

int	sysctl_chg_param_proc_limit (SYSCTL_HANDLER_ARGS)
	sysctl callback for changing net.inet.ip.alias.sctp.param_proc_limit More...

int	sysctl_chg_track_global_addresses (SYSCTL_HANDLER_ARGS)
	sysctl callback for changing net.inet.ip.alias.sctp.track_global_addresses More...

void	AliasSctpInit (struct libalias *la)
	Initialises the SCTP NAT Implementation. More...

void	AliasSctpTerm (struct libalias *la)
	Cleans-up the SCTP NAT Implementation prior to unloading. More...

int	SctpAlias (struct libalias la, struct ip pip, int direction)
	Handles SCTP packets passed from libalias. More...

static uint32_t	local_sctp_finalize_crc32 (uint32_t crc32c)
	Send an AbortM or ErrorM. More...

Variables
static u_int	sysctl_log_level = 0
	net.inet.ip.alias.sctp.log_level More...

static u_int	sysctl_init_timer = 15
	net.inet.ip.alias.sctp.init_timer More...

static u_int	sysctl_up_timer = 300
	net.inet.ip.alias.sctp.up_timer More...

static u_int	sysctl_shutdown_timer = 15
	net.inet.ip.alias.sctp.shutdown_timer More...

static u_int	sysctl_holddown_timer = 0
	net.inet.ip.alias.sctp.holddown_timer More...

static u_int	sysctl_hashtable_size = SN_DEFAULT_HASH_SIZE
	net.inet.ip.alias.sctp.hashtable_size More...

static u_int	sysctl_error_on_ootb = 1
	net.inet.ip.alias.sctp.error_on_ootb More...

static u_int	sysctl_accept_global_ootb_addip = 0
	net.inet.ip.alias.sctp.accept_global_ootb_addip More...

static u_int	sysctl_initialising_chunk_proc_limit = 2
	net.inet.ip.alias.sctp.initialising_chunk_proc_limit More...

static u_int	sysctl_chunk_proc_limit = 5
	net.inet.ip.alias.sctp.param_proc_limit More...

static u_int	sysctl_param_proc_limit = 25
	net.inet.ip.alias.sctp.param_proc_limit More...

static u_int	sysctl_track_global_addresses = 0
	net.inet.ip.alias.sctp.track_global_addresses More...

Macro Definition Documentation

◆ SCTP_MIDDLEBOX_FLAG

#define SCTP_MIDDLEBOX_FLAG 0x02

◆ SCTP_MISSING_NAT

#define SCTP_MISSING_NAT 0x00b1

◆ SCTP_NAT_TABLE_COLLISION

#define SCTP_NAT_TABLE_COLLISION 0x00b0

◆ SCTP_VTAG_PARAM

#define SCTP_VTAG_PARAM 0xC007

Function Documentation

◆ Add_Global_Address_to_List()

static int Add_Global_Address_to_List	(	struct sctp_nat_assoc *	assoc,
		struct sctp_GlobalAddress *	G_addr
	)

static

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.

Parameters

assoc	Pointer to the association this SCTP Message belongs to
G_addr	Pointer to the global address to add

Returns: 1 - success | 0 - fail

Definition at line 1474 of file alias_sctp.c.

◆ AliasSctpInit()

void AliasSctpInit ( struct libalias * la )

Initialises the SCTP NAT Implementation.

Creates the look-up tables and the timer queue and initialises all state variables

Parameters

la	Pointer to the relevant libalias instance

Definition at line 653 of file alias_sctp.c.

Referenced by LibAliasInit().

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◆ AliasSctpTerm()

void AliasSctpTerm ( struct libalias * la )

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

Parameters

la	Pointer to the relevant libalias instance

Definition at line 694 of file alias_sctp.c.

Referenced by LibAliasInit(), and LibAliasUninit().

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◆ local_sctp_finalize_crc32()

static uint32_t local_sctp_finalize_crc32 ( uint32_t crc32c )

static

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

Parameters

la	Pointer to the relevant libalias instance
sm	Pointer to sctp message information
assoc	Pointer to current association details
sndrply	SN_SEND_ABORT \| SN_REPLY_ABORT \| SN_REPLY_ERROR
direction	SN_TO_LOCAL \| SN_TO_GLOBAL

Definition at line 895 of file alias_sctp.c.

◆ MALLOC_DEFINE()

static MALLOC_DEFINE	(	M_SCTPNAT	,
		"sctpnat"	,
		"sctp nat dbs"
	)

static

◆ SctpAlias()

int SctpAlias	(	struct libalias *	la,
		struct ip *	pip,
		int	direction
	)

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

Parameters

la	Pointer to the relevant libalias instance
pip	Pointer to IP packet to process
direction	SN_TO_LOCAL \| SN_TO_GLOBAL

Returns: PKT_ALIAS_OK | PKT_ALIAS_IGNORE | PKT_ALIAS_ERROR

Definition at line 741 of file alias_sctp.c.

Referenced by LibAliasInLocked(), and LibAliasOutLocked().

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◆ TxAbortErrorM()

static void TxAbortErrorM	(	struct libalias *	la,
		struct sctp_nat_msg *	sm,
		struct sctp_nat_assoc *	assoc,
		int	sndrply,
		int	direction
	)

static

Definition at line 932 of file alias_sctp.c.

Macros

Functions

Variables

Macro Definition Documentation

◆ SCTP_MIDDLEBOX_FLAG

◆ SCTP_MISSING_NAT

◆ SCTP_NAT_TABLE_COLLISION

◆ SCTP_VTAG_PARAM

Function Documentation

◆ Add_Global_Address_to_List()

◆ AliasSctpInit()

◆ AliasSctpTerm()

◆ local_sctp_finalize_crc32()

◆ MALLOC_DEFINE()

◆ SctpAlias()

◆ TxAbortErrorM()