strongswan-ext/src/charon/threads/kernel_interface.c

/**
 * @file kernel_interface.c
 *
 * @brief Implementation of kernel_interface_t.
 *
 */

/*
 * Copyright (C) 2006 Tobias Brunner, Daniel Roethlisberger
 * Copyright (C) 2005-2006 Martin Willi
 * Copyright (C) 2005 Jan Hutter
 * Hochschule fuer Technik Rapperswil
 * Copyright (C) 2003 Herbert Xu.
 * 
 * Contains modified parts from pluto.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/xfrm.h>
#include <linux/udp.h>
#include <pthread.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>

#include "kernel_interface.h"

#include <daemon.h>
#include <utils/linked_list.h>
#include <queues/jobs/delete_child_sa_job.h>
#include <queues/jobs/rekey_child_sa_job.h>
#include <queues/jobs/acquire_job.h>

/** kernel level protocol identifiers */
#define KERNEL_ESP 50
#define KERNEL_AH 51

/** default priority of installed policies */
#define PRIO_LOW 3000
#define PRIO_HIGH 2000

#define BUFFER_SIZE 1024

/**
 * returns a pointer to the first rtattr following the nlmsghdr *nlh and the 
 * 'usual' netlink data x like 'struct xfrm_usersa_info' 
 */
#define XFRM_RTA(nlh, x) ((struct rtattr*)(NLMSG_DATA(nlh) + NLMSG_ALIGN(sizeof(x))))
/**
 * returns a pointer to the next rtattr following rta.
 * !!! do not use this to parse messages. use RTA_NEXT and RTA_OK instead !!!
 */
#define XFRM_RTA_NEXT(rta) ((struct rtattr*)(((char*)(rta)) + RTA_ALIGN((rta)->rta_len)))
/**
 * returns the total size of attached rta data 
 * (after 'usual' netlink data x like 'struct xfrm_usersa_info') 
 */
#define XFRM_PAYLOAD(nlh, x) NLMSG_PAYLOAD(nlh, sizeof(x))

typedef struct kernel_algorithm_t kernel_algorithm_t;

/**
 * Mapping from the algorithms defined in IKEv2 to
 * kernel level algorithm names and their key length
 */
struct kernel_algorithm_t {
	/**
	 * Identifier specified in IKEv2
	 */
	int ikev2_id;
	
	/**
	 * Name of the algorithm, as used as kernel identifier
	 */
	char *name;
	
	/**
	 * Key length in bits, if fixed size
	 */
	u_int key_size;
};
#define END_OF_LIST -1

/**
 * Algorithms for encryption
 */
kernel_algorithm_t encryption_algs[] = {
/*	{ENCR_DES_IV64, 	"***", 			0}, */
	{ENCR_DES, 			"des", 			64},
	{ENCR_3DES, 		"des3_ede",		192},
/*	{ENCR_RC5, 			"***", 			0}, */
/*	{ENCR_IDEA, 		"***",			0}, */
	{ENCR_CAST, 		"cast128",		0},
	{ENCR_BLOWFISH, 	"blowfish",		0},
/*	{ENCR_3IDEA, 		"***",			0}, */
/*	{ENCR_DES_IV32, 	"***",			0}, */
	{ENCR_NULL, 		"cipher_null",	0},
	{ENCR_AES_CBC, 		"aes",			0},
/*	{ENCR_AES_CTR, 		"***",			0}, */
	{END_OF_LIST, 		NULL,			0},
};

/**
 * Algorithms for integrity protection
 */
kernel_algorithm_t integrity_algs[] = {
	{AUTH_HMAC_MD5_96, 	"md5",			128},
	{AUTH_HMAC_SHA1_96,	"sha1",			160},
/*	{AUTH_DES_MAC,		"***",			0}, */
/*	{AUTH_KPDK_MD5,		"***",			0}, */
/*	{AUTH_AES_XCBC_96,	"***",			0}, */
	{END_OF_LIST, 		NULL,			0},
};

/**
 * Look up a kernel algorithm name and its key size
 */
char* lookup_algorithm(kernel_algorithm_t *kernel_algo, 
					   algorithm_t *ikev2_algo, u_int *key_size)
{
	while (kernel_algo->ikev2_id != END_OF_LIST)
	{
		if (ikev2_algo->algorithm == kernel_algo->ikev2_id)
		{
			/* match, evaluate key length */
			if (ikev2_algo->key_size)
			{	/* variable length */
				*key_size = ikev2_algo->key_size;
			}
			else
			{	/* fixed length */
				*key_size = kernel_algo->key_size;
			}
			return kernel_algo->name;
		}
		kernel_algo++;
	}
	return NULL;	
}



typedef struct kernel_policy_t kernel_policy_t;

/**
 * Installed kernel policy. 
 */
struct kernel_policy_t {
	
	/** direction of this policy: in, out, forward */
	u_int8_t direction;
	
	/** reqid of the policy */
	u_int32_t reqid;
	
	/** parameters of installed policy */
	struct xfrm_selector sel;
	
	/** by how many CHILD_SA's this policy is used */
	u_int refcount;
};


typedef struct private_kernel_interface_t private_kernel_interface_t;

/**
 * Private Variables and Functions of kernel_interface class.
 */
struct private_kernel_interface_t {
	/**
	 * Public part of the kernel_interface_t object.
	 */
	kernel_interface_t public;
	
	/**
	 * List of installed policies (kernel_policy_t)
	 */
	linked_list_t *policies;
	
	/**
	 * Mutex locks access to policies list.
	 */
	pthread_mutex_t pol_mutex;
	
	/**
	 * Netlink communication socket.
	 */
	int socket;
	
	/**
	 * Process id of kernel thread
	 */
	pid_t pid;
	
	/**
	 * Sequence number for messages.
	 */
	u_int32_t seq;
	
	/** 
	 * List of responded messages.
	 */
	linked_list_t *responses;
	
	/**
	 * Thread which receives messages.
	 */
	pthread_t thread;
	
	/**
	 * Mutex locks access to replies list.
	 */
	pthread_mutex_t rep_mutex;
	
	/**
	 * Condvar allows signaling of threads waiting for a reply.
	 */
	pthread_cond_t condvar;
	
	/**
	 * Logger for XFRM stuff
	 */
	logger_t *logger;
};


/**
 * Send a message down to the kernel and wait for its response
 */
static status_t send_message(private_kernel_interface_t *this,
							 struct nlmsghdr *request, struct nlmsghdr **response)
{
	size_t length;
	struct sockaddr_nl addr;
	
	request->nlmsg_seq = ++this->seq;
	request->nlmsg_pid = 0;
	
	memset(&addr, 0, sizeof(struct sockaddr_nl));
	addr.nl_family = AF_NETLINK;
	addr.nl_pid = 0;
	addr.nl_groups = 0;
	
	length = sendto(this->socket,(void *)request, request->nlmsg_len, 0, 
					(struct sockaddr *)&addr, sizeof(addr));
	
	if (length < 0)
	{
		return FAILED;
	}
	else if (length != request->nlmsg_len)
	{
		return FAILED;
	}
	
	pthread_mutex_lock(&(this->rep_mutex));
	
	while (TRUE)
	{
		iterator_t *iterator; 
		bool found = FALSE;
		/* search list, break if found */
		iterator = this->responses->create_iterator(this->responses, TRUE);
		while (iterator->has_next(iterator))
		{
			struct nlmsghdr *listed_response;
			iterator->current(iterator, (void**)&listed_response);
			if (listed_response->nlmsg_seq == request->nlmsg_seq)
			{
				/* matches our request, this is the reply */
				*response = listed_response;
				iterator->remove(iterator);
				found = TRUE;
				break;
			}
		}
		iterator->destroy(iterator);
		
		if (found)
		{
			break;
		}
		/* TODO: we should time out, if something goes wrong!??? */
		pthread_cond_wait(&(this->condvar), &(this->rep_mutex));
	}
	
	pthread_mutex_unlock(&(this->rep_mutex));
	
	return SUCCESS;
}

/**
 * Implementation of private_kernel_interface_t.receive_messages.
 */
static void receive_messages(private_kernel_interface_t *this)
{
	while(TRUE) 
	{
		unsigned char response[BUFFER_SIZE];
		struct nlmsghdr *hdr, *listed_response;
		while (TRUE)
		{
			struct sockaddr_nl addr;
			socklen_t addr_length;
			size_t length;
			
			addr_length = sizeof(addr);
			
			length = recvfrom(this->socket, &response, sizeof(response), 0, (struct sockaddr*)&addr, &addr_length);
			if (length < 0)
			{
				if (errno == EINTR)
				{
					/* interrupted, try again */
					continue;
				}
				charon->kill(charon, "receiving from netlink socket failed");
			}
			if (!NLMSG_OK((struct nlmsghdr *)response, length))
			{
				/* bad netlink message */
				continue;
			}
			if (addr.nl_pid != 0)
			{
				/* not from kernel. not interested, try another one */
				continue;
			}
			/* good message, handle it */
			break;
		}
		
		/* we handle ACQUIRE and EXPIRE messages directly */
		hdr = (struct nlmsghdr*)response;
		if (hdr->nlmsg_type == XFRM_MSG_ACQUIRE)
		{
			u_int32_t reqid = 0;
			job_t *job;
			struct rtattr *rthdr = XFRM_RTA(hdr, struct xfrm_user_acquire);
			size_t rtsize = XFRM_PAYLOAD(hdr, struct xfrm_user_tmpl);
			if (RTA_OK(rthdr, rtsize))
			{
				if (rthdr->rta_type == XFRMA_TMPL)
				{
					struct xfrm_user_tmpl* tmpl = (struct xfrm_user_tmpl*)RTA_DATA(rthdr);
					reqid = tmpl->reqid;
				}
			}
			if (reqid == 0)
			{
				this->logger->log(this->logger, ERROR,
								  "Received a XFRM_MSG_ACQUIRE, but no reqid found");
			}
			else
			{
				this->logger->log(this->logger, CONTROL|LEVEL1, 
								"Received a XFRM_MSG_ACQUIRE");
				this->logger->log(this->logger, CONTROL,
								  "creating acquire job for CHILD_SA with reqid %d",
								  reqid);
				job = (job_t*)acquire_job_create(reqid);
				charon->job_queue->add(charon->job_queue, job);
			}
		}
		else if (hdr->nlmsg_type == XFRM_MSG_EXPIRE)
		{
			job_t *job;
			protocol_id_t protocol;
			u_int32_t spi, reqid;
			struct xfrm_user_expire *expire;
			
			expire = (struct xfrm_user_expire*)NLMSG_DATA(hdr);
			protocol = expire->state.id.proto == KERNEL_ESP ?
					PROTO_ESP : PROTO_AH;
			spi = expire->state.id.spi;
			reqid = expire->state.reqid;
			
			this->logger->log(this->logger, CONTROL|LEVEL1,
							  "Received a XFRM_MSG_EXPIRE");
			this->logger->log(this->logger, CONTROL,
							  "creating %s job for %s CHILD_SA 0x%x (reqid %d)",
							  expire->hard ? "delete" : "rekey",
							  mapping_find(protocol_id_m, protocol), ntohl(spi),
							  reqid);
			if (expire->hard)
			{
				job = (job_t*)delete_child_sa_job_create(reqid, protocol, spi);
			}
			else
			{
				job = (job_t*)rekey_child_sa_job_create(reqid, protocol, spi);
			}
			charon->job_queue->add(charon->job_queue, job);
		}
		/* NLMSG_ERROR is sent back for acknowledge (or on error), an
		* XFRM_MSG_NEWSA is returned when we alloc spis and when
		* updating SAs.
		* XFRM_MSG_NEWPOLICY is returned when we query a policy.
		* list these responses for the sender
		*/
		else if (hdr->nlmsg_type == NLMSG_ERROR ||
				 hdr->nlmsg_type == XFRM_MSG_NEWSA ||
				 hdr->nlmsg_type == XFRM_MSG_NEWPOLICY)
		{
			/* add response to queue */
			listed_response = malloc(hdr->nlmsg_len);
			memcpy(listed_response, &response, hdr->nlmsg_len);
			
			pthread_mutex_lock(&(this->rep_mutex));
			this->responses->insert_last(this->responses, (void*)listed_response);
			pthread_mutex_unlock(&(this->rep_mutex));
			/* signal ALL waiting threads */
			pthread_cond_broadcast(&(this->condvar));
		}
		/* we are not interested in anything other.
		* anyway, move on to the next message */
		continue;
	}
}

/**
 * convert a host_t to a struct xfrm_address
 */
static void host2xfrm(host_t *host, xfrm_address_t *xfrm)
{
	chunk_t chunk = host->get_address(host);
	memcpy(xfrm, chunk.ptr, max(chunk.len, sizeof(xfrm_address_t)));	
}

/**
 * Implementation of kernel_interface_t.get_spi.
 */
static status_t get_spi(private_kernel_interface_t *this, 
						host_t *src, host_t *dst, 
						protocol_id_t protocol, u_int32_t reqid,
						u_int32_t *spi)
{
	unsigned char request[BUFFER_SIZE];
	struct nlmsghdr *response;
	struct nlmsghdr *hdr;
	struct xfrm_userspi_info *userspi;
	
	memset(&request, 0, sizeof(request));
	status_t status = SUCCESS;
	
	this->logger->log(this->logger, CONTROL|LEVEL2, "getting spi");
	
	hdr = (struct nlmsghdr*)request;
	hdr->nlmsg_flags = NLM_F_REQUEST;
	hdr->nlmsg_type = XFRM_MSG_ALLOCSPI;
	hdr->nlmsg_len = NLMSG_LENGTH(sizeof(struct xfrm_userspi_info));

	userspi = (struct xfrm_userspi_info*)NLMSG_DATA(hdr);
	host2xfrm(src, &userspi->info.saddr);
	host2xfrm(dst, &userspi->info.id.daddr);
	userspi->info.id.proto = (protocol == PROTO_ESP) ? KERNEL_ESP : KERNEL_AH;
	userspi->info.mode = TRUE; /* tunnel mode */
	userspi->info.reqid = reqid;
	userspi->info.family = src->get_family(src);
	userspi->min = 0xc0000000;
	userspi->max = 0xcFFFFFFF;
	
	if (send_message(this, hdr, &response) != SUCCESS)
	{
		this->logger->log(this->logger, ERROR, "netlink communication failed");
		return FAILED;
	}
	else if (response->nlmsg_type == NLMSG_ERROR)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_ALLOCSPI got an error: %s",
						  strerror(-((struct nlmsgerr*)NLMSG_DATA(response))->error));
		status = FAILED;
	}
	else if (response->nlmsg_type != XFRM_MSG_NEWSA)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_ALLOCSPI got a unknown reply");
		status = FAILED;
	}
	else if (response->nlmsg_len < NLMSG_LENGTH(sizeof(struct xfrm_usersa_info)))
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_ALLOCSPI got an invalid reply");
		status = FAILED;
	}
	else
	{
		*spi = ((struct xfrm_usersa_info*)NLMSG_DATA(response))->id.spi;
		this->logger->log(this->logger, CONTROL|LEVEL1, "SPI is 0x%x", *spi);
	}
	free(response);
	
	return status;
}

/**
 * Implementation of kernel_interface_t.add_sa.
 */
static status_t add_sa(private_kernel_interface_t *this,
					   host_t *src, host_t *dst, u_int32_t spi,
					   protocol_id_t protocol, u_int32_t reqid,
					   u_int64_t expire_soft, u_int64_t expire_hard,
					   algorithm_t *enc_alg, algorithm_t *int_alg,
					   prf_plus_t *prf_plus, natt_conf_t *natt,
					   bool replace)
{
	unsigned char request[BUFFER_SIZE];
	struct nlmsghdr *response;
	char *alg_name;
	size_t key_size;
	struct nlmsghdr *hdr;
	struct xfrm_usersa_info *sa;
	
	memset(&request, 0, sizeof(request));
	status_t status = SUCCESS;
	
	this->logger->log(this->logger, CONTROL|LEVEL2, "adding SA");

	hdr = (struct nlmsghdr*)request;
	hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
	hdr->nlmsg_type = replace ? XFRM_MSG_UPDSA : XFRM_MSG_NEWSA;
	hdr->nlmsg_len = NLMSG_LENGTH(sizeof(struct xfrm_usersa_info));
	
	sa = (struct xfrm_usersa_info*)NLMSG_DATA(hdr);
	host2xfrm(src, &sa->saddr);
	host2xfrm(dst, &sa->id.daddr);
	sa->id.spi = spi;
	sa->id.proto = (protocol == PROTO_ESP) ? KERNEL_ESP : KERNEL_AH;
	sa->family = src->get_family(src);
	sa->mode = TRUE; /* tunnel mode */
	sa->replay_window = 32;
	sa->reqid = reqid;
	/* we currently do not expire SAs by volume/packet count */
	sa->lft.soft_byte_limit = XFRM_INF;
	sa->lft.hard_byte_limit = XFRM_INF;
	sa->lft.soft_packet_limit = XFRM_INF;
	sa->lft.hard_packet_limit = XFRM_INF;
	/* we use lifetimes since added, not since used */
	sa->lft.soft_add_expires_seconds = expire_soft;
	sa->lft.hard_add_expires_seconds = expire_hard;
	sa->lft.soft_use_expires_seconds = 0;
	sa->lft.hard_use_expires_seconds = 0;
	
	struct rtattr *rthdr = XFRM_RTA(hdr, struct xfrm_usersa_info);
	
	if (enc_alg->algorithm != ENCR_UNDEFINED)
	{
		rthdr->rta_type = XFRMA_ALG_CRYPT;
		alg_name = lookup_algorithm(encryption_algs, enc_alg, &key_size);
		if (alg_name == NULL)
		{
			this->logger->log(this->logger, ERROR, "Algorithm %s not supported by kernel!", 
							  mapping_find(encryption_algorithm_m, enc_alg->algorithm));
			return FAILED;
		}
		this->logger->log(this->logger, CONTROL|LEVEL2, "  using encryption algorithm %s with key size %d",
						  mapping_find(encryption_algorithm_m, enc_alg->algorithm), key_size);
		
		rthdr->rta_len = RTA_LENGTH(sizeof(struct xfrm_algo) + key_size);
		hdr->nlmsg_len += rthdr->rta_len;
		if (hdr->nlmsg_len > sizeof(request))
		{
			return FAILED;
		}
		
		struct xfrm_algo* algo = (struct xfrm_algo*)RTA_DATA(rthdr);
		algo->alg_key_len = key_size;
		strcpy(algo->alg_name, alg_name);
		prf_plus->get_bytes(prf_plus, key_size / 8, algo->alg_key);
		
		rthdr = XFRM_RTA_NEXT(rthdr);
	}
	
	if (int_alg->algorithm  != AUTH_UNDEFINED)
	{
		rthdr->rta_type = XFRMA_ALG_AUTH;
		alg_name = lookup_algorithm(integrity_algs, int_alg, &key_size);
		if (alg_name == NULL)
		{
			this->logger->log(this->logger, ERROR, "Algorithm %s not supported by kernel!", 
							  mapping_find(integrity_algorithm_m, int_alg->algorithm));
			return FAILED;
		}
		this->logger->log(this->logger, CONTROL|LEVEL2, "  using integrity algorithm %s with key size %d",
						  mapping_find(integrity_algorithm_m, int_alg->algorithm), key_size);
		
		rthdr->rta_len = RTA_LENGTH(sizeof(struct xfrm_algo) + key_size);
		hdr->nlmsg_len += rthdr->rta_len;
		if (hdr->nlmsg_len > sizeof(request))
		{
			return FAILED;
		}
		
		struct xfrm_algo* algo = (struct xfrm_algo*)RTA_DATA(rthdr);
		algo->alg_key_len = key_size;
		strcpy(algo->alg_name, alg_name);
		prf_plus->get_bytes(prf_plus, key_size / 8, algo->alg_key);
		
		rthdr = XFRM_RTA_NEXT(rthdr);
	}
	
	/* TODO: add IPComp here */
	
	if (natt)
	{
		rthdr->rta_type = XFRMA_ENCAP;
		rthdr->rta_len = RTA_LENGTH(sizeof(struct xfrm_encap_tmpl));

		hdr->nlmsg_len += rthdr->rta_len;
		if (hdr->nlmsg_len > sizeof(request))
		{
			return FAILED;
		}

		struct xfrm_encap_tmpl* encap = (struct xfrm_encap_tmpl*)RTA_DATA(rthdr);
		encap->encap_type = UDP_ENCAP_ESPINUDP;
		encap->encap_sport = htons(natt->sport);
		encap->encap_dport = htons(natt->dport);
		memset(&encap->encap_oa, 0, sizeof (xfrm_address_t));
		/* encap_oa could probably be derived from the 
		 * traffic selectors [rfc4306, p39]. In the netlink kernel implementation 
		 * pluto does the same as we do here but it uses encap_oa in the 
		 * pfkey implementation. BUT as /usr/src/linux/net/key/af_key.c indicates 
		 * the kernel ignores it anyway
		 *   -> does that mean that NAT-T encap doesn't work in transport mode?
		 * No. The reason the kernel ignores NAT-OA is that it recomputes 
		 * (or, rather, just ignores) the checksum. If packets pass
		 * the IPSec checks it marks them "checksum ok" so OA isn't needed. */
		
		rthdr = XFRM_RTA_NEXT(rthdr);
	}

	if (send_message(this, hdr, &response) != SUCCESS)
	{
		this->logger->log(this->logger, ERROR, "netlink communication failed");
		return FAILED;
	}
	else if (response->nlmsg_type != NLMSG_ERROR)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_NEWSA not acknowledged");
		status = FAILED;
	}
	else if (((struct nlmsgerr*)NLMSG_DATA(response))->error)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_NEWSA got an error: %s",
						  strerror(-((struct nlmsgerr*)NLMSG_DATA(response))->error));
		status = FAILED;
	}
	
	free(response);
	return status;
}

/**
 * Implementation of kernel_interface_t.update_sa.
 */
static status_t update_sa(
		private_kernel_interface_t *this,
		host_t *src, host_t *dst,
		host_t *new_src, host_t *new_dst, 
		host_diff_t src_changes, host_diff_t dst_changes,
		u_int32_t spi, protocol_id_t protocol)
{
	unsigned char request[BUFFER_SIZE];
	struct nlmsghdr *update, *response;
	struct nlmsghdr *hdr;
	struct xfrm_usersa_id *sa_id;
	
	memset(&request, 0, sizeof(request));
	status_t status = SUCCESS;
	
	this->logger->log(this->logger, CONTROL|LEVEL2, "getting SA");

	hdr = (struct nlmsghdr*)request;
	hdr->nlmsg_flags = NLM_F_REQUEST;
	hdr->nlmsg_type = XFRM_MSG_GETSA;
	hdr->nlmsg_len = NLMSG_LENGTH(sizeof(struct xfrm_usersa_id));

	sa_id = (struct xfrm_usersa_id*)NLMSG_DATA(hdr);
	host2xfrm(dst, &sa_id->daddr);
	sa_id->spi = spi;
	sa_id->proto = (protocol == PROTO_ESP) ? KERNEL_ESP : KERNEL_AH;
	sa_id->family = dst->get_family(dst);
	
	if (send_message(this, hdr, &update) != SUCCESS)
	{
		this->logger->log(this->logger, ERROR, "netlink communication failed");
		return FAILED;
	}
	else if (update->nlmsg_type == NLMSG_ERROR)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_GETSA got an error: %s",
						  strerror(-((struct nlmsgerr*)NLMSG_DATA(update))->error));
		free(update);
		return FAILED;
	}
	else if (update->nlmsg_type != XFRM_MSG_NEWSA)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_GETSA got a unknown reply");
		free(update);
		return FAILED;
	}
	else if (update->nlmsg_len < NLMSG_LENGTH(sizeof(struct xfrm_usersa_info)))
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_GETSA got an invalid reply");
		free(update);
		return FAILED;
	}
	
	this->logger->log(this->logger, CONTROL|LEVEL2, "updating SA");
	update->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;	
	update->nlmsg_type = XFRM_MSG_UPDSA;
	
	struct xfrm_usersa_info *sa = (struct xfrm_usersa_info*)NLMSG_DATA(update);
	if (src_changes & HOST_DIFF_ADDR)
	{
		host2xfrm(new_src, &sa->saddr);
	}

	if (dst_changes & HOST_DIFF_ADDR)
	{
		this->logger->log(this->logger, CONTROL|LEVEL2, "destination address changed! replacing SA");	
		
		update->nlmsg_type = XFRM_MSG_NEWSA;
		host2xfrm(new_dst, &sa->id.daddr);
	}
	
	if (src_changes & HOST_DIFF_PORT || dst_changes & HOST_DIFF_PORT)
	{
		struct rtattr *rthdr = XFRM_RTA(update, struct xfrm_usersa_info);
		size_t rtsize = XFRM_PAYLOAD(update, struct xfrm_usersa_info);
		while (RTA_OK(rthdr, rtsize))
		{
			if (rthdr->rta_type == XFRMA_ENCAP)
			{
				struct xfrm_encap_tmpl* encap = (struct xfrm_encap_tmpl*)RTA_DATA(rthdr);
				encap->encap_sport = ntohs(new_src->get_port(new_src));
				encap->encap_dport = ntohs(new_dst->get_port(new_dst));
				break;
			}
			rthdr = RTA_NEXT(rthdr, rtsize);
		}
	}
	
	if (send_message(this, update, &response) != SUCCESS)
	{
		this->logger->log(this->logger, ERROR, "netlink communication failed");
		free(update);
		return FAILED;
	}
	else if (response->nlmsg_type != NLMSG_ERROR)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_XXXSA not acknowledged");
		status = FAILED;
	}
	else if (((struct nlmsgerr*)NLMSG_DATA(response))->error)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_XXXSA got an error: %s",
						  strerror(-((struct nlmsgerr*)NLMSG_DATA(response))->error));
		status = FAILED;
	}
	else if (dst_changes & HOST_DIFF_ADDR)
	{
		this->logger->log(this->logger, CONTROL|LEVEL2, "deleting old SA");
		status = this->public.del_sa(&this->public, dst, spi, protocol);
	}
	
	free(update);
	free(response);
	return status;
}

/**
 * Implementation of kernel_interface_t.query_sa.
 */
static status_t query_sa(private_kernel_interface_t *this, host_t *dst,
						 u_int32_t spi, protocol_id_t protocol, u_int32_t *use_time)
{
	unsigned char request[BUFFER_SIZE];
	struct nlmsghdr *response;
	struct nlmsghdr *hdr;
	struct xfrm_usersa_id *sa_id;
	struct xfrm_usersa_info *sa_info;
	
	this->logger->log(this->logger, CONTROL|LEVEL2, "querying SA");
	memset(&request, 0, sizeof(request));
	
	hdr = (struct nlmsghdr*)request;
	hdr->nlmsg_flags = NLM_F_REQUEST;
	hdr->nlmsg_type = XFRM_MSG_GETSA;
	hdr->nlmsg_len = NLMSG_LENGTH(sizeof(struct xfrm_usersa_info));

	sa_id = (struct xfrm_usersa_id*)NLMSG_DATA(hdr);
	host2xfrm(dst, &sa_id->daddr);
	sa_id->spi = spi;
	sa_id->proto = (protocol == PROTO_ESP) ? KERNEL_ESP : KERNEL_AH;
	sa_id->family = dst->get_family(dst);
	
	if (send_message(this, hdr, &response) != SUCCESS)
	{
		this->logger->log(this->logger, ERROR, "netlink communication failed");
		return FAILED;
	}
	else if (response->nlmsg_type != XFRM_MSG_NEWSA)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_GETSA not acknowledged");
		free(response);
		return FAILED;
	}
	else if (response->nlmsg_len < NLMSG_LENGTH(sizeof(struct xfrm_usersa_info)))
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_GETSA got an invalid reply");
		free(response);
		return FAILED;
	}
	
	sa_info = (struct xfrm_usersa_info*)NLMSG_DATA(response);
	*use_time = sa_info->curlft.use_time;
	
	free(response);
	return SUCCESS;
}

/**
 * Implementation of kernel_interface_t.del_sa.
 */
static status_t del_sa(private_kernel_interface_t *this, host_t *dst,
					   u_int32_t spi, protocol_id_t protocol)
{
	unsigned char request[BUFFER_SIZE];
	struct nlmsghdr *response;
	struct nlmsghdr *hdr;
	struct xfrm_usersa_id *sa_id;
	
	memset(&request, 0, sizeof(request));
	status_t status = SUCCESS;
	
	this->logger->log(this->logger, CONTROL|LEVEL2, "deleting SA");
	
	hdr = (struct nlmsghdr*)request;
	hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
	hdr->nlmsg_type = XFRM_MSG_DELSA;
	hdr->nlmsg_len = NLMSG_LENGTH(sizeof(struct xfrm_usersa_id));
	
	sa_id = (struct xfrm_usersa_id*)NLMSG_DATA(hdr);
	host2xfrm(dst, &sa_id->daddr);
	sa_id->spi = spi;
	sa_id->proto = (protocol == PROTO_ESP) ? KERNEL_ESP : KERNEL_AH;
	sa_id->family = dst->get_family(dst);
	
	if (send_message(this, hdr, &response) != SUCCESS)
	{
		this->logger->log(this->logger, ERROR, "netlink communication failed");
		return FAILED;
	}
	else if (response->nlmsg_type != NLMSG_ERROR)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_DELSA not acknowledged");
		status = FAILED;
	}
	else if (((struct nlmsgerr*)NLMSG_DATA(response))->error)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_DELSA got an error: %s",
						  strerror(-((struct nlmsgerr*)NLMSG_DATA(response))->error));
		status = FAILED;
	}
	
	free(response);
	return status;
}

/**
 * convert a traffic selector address range to subnet and its mask.
 */
static void ts2subnet(traffic_selector_t* ts, 
					  xfrm_address_t *net, u_int8_t *mask)
{
	/* there is no way to do this cleanly, as the address range may
	 * be anything else but a subnet. We use from_addr as subnet 
	 * and try to calculate a usable subnet mask.
	*/
	int byte, bit;
	bool found = FALSE;
	chunk_t from, to;
	size_t size = (ts->get_type(ts) == TS_IPV4_ADDR_RANGE) ? 4 : 16;
	
	from = ts->get_from_address(ts);
	to = ts->get_to_address(ts);
	
	*mask = (size * 8);
	/* go trough all bits of the addresses, beginning in the front.
	 * As longer as they equal, the subnet gets larger */
	for (byte = 0; byte < size; byte++)
	{
		for (bit = 7; bit >= 0; bit--)
		{
			if ((1<<bit & from.ptr[byte]) != (1<<bit & to.ptr[byte]))
			{
				*mask = ((7 - bit) + (byte * 8));
				found = TRUE;
				break;
			}
		}
		if (found)
		{
			break;
		}
	}
	memcpy(net, from.ptr, from.len);
	chunk_free(&from);
	chunk_free(&to);
}

/**
 * convert a traffic selector port range to port/portmask
 */
static void ts2ports(traffic_selector_t* ts, 
					 u_int16_t *port, u_int16_t *mask)
{
	/* linux does not seem to accept complex portmasks. Only
	 * any or a specific port is allowed. We set to any, if we have
	 * a port range, or to a specific, if we have one port only.
	 */
	u_int16_t from, to;
	
	from = ts->get_from_port(ts);
	to = ts->get_to_port(ts);
	
	if (from == to)
	{
		*port = htons(from);
		*mask = ~0;
	}
	else
	{
		*port = 0;
		*mask = 0;
	}
}

/**
 * convert a pair of traffic_selectors to a xfrm_selector
 */
static struct xfrm_selector ts2selector(traffic_selector_t *src, 
										traffic_selector_t *dst)
{
	struct xfrm_selector sel;

	memset(&sel, 0, sizeof(sel));
	sel.family = src->get_type(src) == TS_IPV4_ADDR_RANGE ? AF_INET : AF_INET6;
	/* src or dest proto may be "any" (0), use more restrictive one */
	sel.proto = max(src->get_protocol(src), dst->get_protocol(dst));
	ts2subnet(dst, &sel.daddr, &sel.prefixlen_d);
	ts2subnet(src, &sel.saddr, &sel.prefixlen_s);
	ts2ports(dst, &sel.dport, &sel.dport_mask);
	ts2ports(src, &sel.sport, &sel.sport_mask);
	sel.ifindex = 0;
	sel.user = 0;
	
	return sel;
}

/**
 * Implementation of kernel_interface_t.add_policy.
 */
static status_t add_policy(private_kernel_interface_t *this, 
						   host_t *src, host_t *dst,
						   traffic_selector_t *src_ts,
						   traffic_selector_t *dst_ts,
						   policy_dir_t direction, protocol_id_t protocol,
						   u_int32_t reqid, bool high_prio, bool update)
{
	iterator_t *iterator;
	kernel_policy_t *current, *policy;
	bool found = FALSE;
	unsigned char request[BUFFER_SIZE];
	struct nlmsghdr *response;
	struct xfrm_userpolicy_info *policy_info;
	struct nlmsghdr *hdr;
	status_t status = SUCCESS;
	
	/* create a policy */
	policy = malloc_thing(kernel_policy_t);
	memset(policy, 0, sizeof(kernel_policy_t));
	policy->sel = ts2selector(src_ts, dst_ts);
	policy->direction = direction;
	
	/* find the policy, which matches EXACTLY */
	pthread_mutex_lock(&this->pol_mutex);
	iterator = this->policies->create_iterator(this->policies, TRUE);
	while (iterator->iterate(iterator, (void**)&current))
	{
		if (memcmp(current, policy, sizeof(struct xfrm_selector)) == 0 &&
			policy->direction == current->direction)
		{
			free(policy);
			/* use existing policy */
			if (!update)
			{
				current->refcount++;
				this->logger->log(this->logger, CONTROL|LEVEL1, 
								  "policy already exists, increasing refcount");
				if (!high_prio)
				{
					/* if added policy is for a ROUTED child_sa, do not
					 * overwrite existing INSTALLED policy */
					iterator->destroy(iterator);
					pthread_mutex_unlock(&this->pol_mutex);
					return SUCCESS;
				}
			}
			policy = current;
			found = TRUE;
			break;
		}
	}
	iterator->destroy(iterator);
	if (!found)
	{	/* apply the new one, if we have no such policy */
		this->policies->insert_last(this->policies, policy);
		policy->refcount = 1;
	}
	
	this->logger->log(this->logger, CONTROL|LEVEL2, "adding policy");
	
	memset(&request, 0, sizeof(request));
	hdr = (struct nlmsghdr*)request;
	hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
	hdr->nlmsg_type = XFRM_MSG_UPDPOLICY;
	hdr->nlmsg_len = NLMSG_LENGTH(sizeof(struct xfrm_userpolicy_info));

	policy_info = (struct xfrm_userpolicy_info*)NLMSG_DATA(hdr);
	policy_info->sel = policy->sel;
	policy_info->dir = policy->direction;
	/* calculate priority based on source selector size, small size = high prio */
	policy_info->priority = high_prio ? PRIO_HIGH : PRIO_LOW;
	policy_info->priority -= policy->sel.prefixlen_s * 10;
	policy_info->priority -= policy->sel.proto ? 2 : 0;
	policy_info->priority -= policy->sel.sport_mask ? 1 : 0;
	policy_info->action = XFRM_POLICY_ALLOW;
	policy_info->share = XFRM_SHARE_ANY;
	pthread_mutex_unlock(&this->pol_mutex);
	
	/* policies don't expire */
	policy_info->lft.soft_byte_limit = XFRM_INF;
	policy_info->lft.soft_packet_limit = XFRM_INF;
	policy_info->lft.hard_byte_limit = XFRM_INF;
	policy_info->lft.hard_packet_limit = XFRM_INF;
	policy_info->lft.soft_add_expires_seconds = 0;
	policy_info->lft.hard_add_expires_seconds = 0;
	policy_info->lft.soft_use_expires_seconds = 0;
	policy_info->lft.hard_use_expires_seconds = 0;
	
	struct rtattr *rthdr = XFRM_RTA(hdr, struct xfrm_userpolicy_info);
	rthdr->rta_type = XFRMA_TMPL;

	rthdr->rta_len = sizeof(struct xfrm_user_tmpl);
	rthdr->rta_len = RTA_LENGTH(rthdr->rta_len);

	hdr->nlmsg_len += rthdr->rta_len;
	if (hdr->nlmsg_len > sizeof(request))
	{
		return FAILED;
	}
	
	struct xfrm_user_tmpl *tmpl = (struct xfrm_user_tmpl*)RTA_DATA(rthdr);
	tmpl->reqid = reqid;
	tmpl->id.proto = (protocol == PROTO_AH) ? KERNEL_AH : KERNEL_ESP;
	tmpl->aalgos = tmpl->ealgos = tmpl->calgos = ~0;
	tmpl->mode = TRUE;
	tmpl->family = src->get_family(src);
	
	host2xfrm(src, &tmpl->saddr);
	host2xfrm(dst, &tmpl->id.daddr);
	
	if (send_message(this, hdr, &response) != SUCCESS)
	{
		this->logger->log(this->logger, ERROR, "netlink communication failed");
		return FAILED;
	}
	else if (response->nlmsg_type != NLMSG_ERROR)
	{
		this->logger->log(this->logger, ERROR, 
						  "netlink request XFRM_MSG_UPDPOLICY not acknowledged");
		status = FAILED;
	}
	else if (((struct nlmsgerr*)NLMSG_DATA(response))->error)
	{
		this->logger->log(this->logger, ERROR, 
						  "netlink request XFRM_MSG_UPDPOLICY got an error: %s",
						  strerror(-((struct nlmsgerr*)NLMSG_DATA(response))->error));
		status = FAILED;
	}
	
	free(response);
	return status;
}

/**
 * Implementation of kernel_interface_t.query_policy.
 */
static status_t query_policy(private_kernel_interface_t *this,
							 traffic_selector_t *src_ts, 
							 traffic_selector_t *dst_ts,
							 policy_dir_t direction, u_int32_t *use_time)
{
	unsigned char request[BUFFER_SIZE];
	struct nlmsghdr *response;
	struct nlmsghdr *hdr;
	struct xfrm_userpolicy_id *policy_id;
	struct xfrm_userpolicy_info *policy;
	
	memset(&request, 0, sizeof(request));
	status_t status = SUCCESS;
	
	this->logger->log(this->logger, CONTROL|LEVEL2, "querying policy");

	hdr = (struct nlmsghdr*)request;
	hdr->nlmsg_flags = NLM_F_REQUEST;
	hdr->nlmsg_type = XFRM_MSG_GETPOLICY;
	hdr->nlmsg_len = NLMSG_LENGTH(sizeof(struct xfrm_userpolicy_id));

	policy_id = (struct xfrm_userpolicy_id*)NLMSG_DATA(hdr);
	policy_id->sel = ts2selector(src_ts, dst_ts);
	policy_id->dir = direction;

	if (send_message(this, hdr, &response) != SUCCESS)
	{
		this->logger->log(this->logger, ERROR, "netlink communication failed");
		return FAILED;
	}
	else if (response->nlmsg_type == NLMSG_ERROR)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_GETPOLICY got an error: %s",
						  strerror(-((struct nlmsgerr*)NLMSG_DATA(response))->error));
		free(response);
		return FAILED;
	}
	else if (response->nlmsg_type != XFRM_MSG_NEWPOLICY)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_GETPOLICY got an unknown reply");
		free(response);
		return FAILED;
	}
	else if (response->nlmsg_len < NLMSG_LENGTH(sizeof(struct xfrm_userpolicy_info)))
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_GETPOLICY got an invalid reply");
		free(response);
		return FAILED;
	}

	policy = (struct xfrm_userpolicy_info*)NLMSG_DATA(response);

	*use_time = (time_t)policy->curlft.use_time;
	
	free(response);
	return status;
}

/**
 * Implementation of kernel_interface_t.del_policy.
 */
static status_t del_policy(private_kernel_interface_t *this,
						   traffic_selector_t *src_ts, 
						   traffic_selector_t *dst_ts,
						   policy_dir_t direction)
{
	kernel_policy_t *current, policy, *to_delete = NULL;
	unsigned char request[BUFFER_SIZE];
	struct nlmsghdr *response;
	struct nlmsghdr *hdr;
	struct xfrm_userpolicy_id *policy_id;
	iterator_t *iterator;
	status_t status = SUCCESS;
	
	this->logger->log(this->logger, CONTROL|LEVEL2, "deleting policy");
	
	/* create a policy */
	memset(&policy, 0, sizeof(kernel_policy_t));
	policy.sel = ts2selector(src_ts, dst_ts);
	policy.direction = direction;
	
	/* find the policy */
	pthread_mutex_lock(&this->pol_mutex);
	iterator = this->policies->create_iterator(this->policies, TRUE);
	while (iterator->iterate(iterator, (void**)&current))
	{
		if (memcmp(&current->sel, &policy.sel, sizeof(struct xfrm_selector)) == 0 &&
			policy.direction == current->direction)
		{
			to_delete = current;
			if (--to_delete->refcount > 0)
			{
				/* is used by more SAs, keep in kernel */
				this->logger->log(this->logger, CONTROL|LEVEL1, 
								  "is used by other SAs, not removed");
				iterator->destroy(iterator);
				pthread_mutex_unlock(&this->pol_mutex);
				return SUCCESS;
			}
			/* remove if last reference */
			iterator->remove(iterator);
			break;
		}
	}
	iterator->destroy(iterator);
	pthread_mutex_unlock(&this->pol_mutex);
	if (!to_delete)
	{
		this->logger->log(this->logger, CONTROL|LEVEL2, 
						  "no such policy found");
		return NOT_FOUND;
	}
	
	memset(&request, 0, sizeof(request));
	
	hdr = (struct nlmsghdr*)request;
	hdr->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
	hdr->nlmsg_type = XFRM_MSG_DELPOLICY;
	hdr->nlmsg_len = NLMSG_LENGTH(sizeof(struct xfrm_userpolicy_id));

	policy_id = (struct xfrm_userpolicy_id*)NLMSG_DATA(hdr);
	policy_id->sel = to_delete->sel;
	policy_id->dir = direction;
	
	free(to_delete);
	
	if (send_message(this, hdr, &response) != SUCCESS)
	{
		this->logger->log(this->logger, ERROR, "netlink communication failed");
		return FAILED;
	}
	else if (response->nlmsg_type != NLMSG_ERROR)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_DELPOLICY not acknowledged");
		status = FAILED;
	}
	else if (((struct nlmsgerr*)NLMSG_DATA(response))->error)
	{
		this->logger->log(this->logger, ERROR, "netlink request XFRM_MSG_DELPOLICY got an error: %s",
						  strerror(-((struct nlmsgerr*)NLMSG_DATA(response))->error));
		status = FAILED;
	}
	
	free(response);
	return status;
}

/**
 * Implementation of kernel_interface_t.destroy.
 */
static void destroy(private_kernel_interface_t *this)
{	
	pthread_cancel(this->thread);
	pthread_join(this->thread, NULL);
	close(this->socket);
	this->responses->destroy(this->responses);
	this->policies->destroy(this->policies);
	free(this);
}

/*
 * Described in header.
 */
kernel_interface_t *kernel_interface_create()
{
	struct sockaddr_nl addr;
	private_kernel_interface_t *this = malloc_thing(private_kernel_interface_t);
	
	/* public functions */
	this->public.get_spi = (status_t(*)(kernel_interface_t*,host_t*,host_t*,protocol_id_t,u_int32_t,u_int32_t*))get_spi;
	this->public.add_sa  = (status_t(*)(kernel_interface_t *,host_t*,host_t*,u_int32_t,protocol_id_t,u_int32_t,u_int64_t,u_int64_t,algorithm_t*,algorithm_t*,prf_plus_t*,natt_conf_t*,bool))add_sa;
	this->public.update_sa = (status_t(*)(kernel_interface_t*,host_t*,u_int32_t,protocol_id_t,host_t*,host_t*,host_diff_t,host_diff_t))update_sa;
	this->public.query_sa = (status_t(*)(kernel_interface_t*,host_t*,u_int32_t,protocol_id_t,u_int32_t*))query_sa;
	this->public.del_sa = (status_t(*)(kernel_interface_t*,host_t*,u_int32_t,protocol_id_t))del_sa;
	this->public.add_policy = (status_t(*)(kernel_interface_t*,host_t*,host_t*,traffic_selector_t*,traffic_selector_t*,policy_dir_t,protocol_id_t,u_int32_t,bool,bool))add_policy;
	this->public.query_policy = (status_t(*)(kernel_interface_t*,traffic_selector_t*,traffic_selector_t*,policy_dir_t,u_int32_t*))query_policy;
	this->public.del_policy = (status_t(*)(kernel_interface_t*,traffic_selector_t*,traffic_selector_t*,policy_dir_t))del_policy;
	this->public.destroy = (void(*)(kernel_interface_t*)) destroy;

	/* private members */
	this->pid = getpid();
	this->responses = linked_list_create();
	this->policies = linked_list_create();
	this->logger = logger_manager->get_logger(logger_manager, XFRM);
	pthread_mutex_init(&(this->rep_mutex),NULL);
	pthread_mutex_init(&(this->pol_mutex),NULL);
	pthread_cond_init(&(this->condvar),NULL);
	this->seq = 0;
	
	/* open netlink socket */
	this->socket = socket(PF_NETLINK, SOCK_RAW, NETLINK_XFRM);
	if (this->socket <= 0)
	{
		this->responses->destroy(this->responses);
		free(this);
		charon->kill(charon, "Unable to create netlink socket");	
	}
	
	/* bind the socket and reqister for ACQUIRE & EXPIRE */
	addr.nl_family = AF_NETLINK;
	addr.nl_pid = getpid();
	addr.nl_groups = XFRMGRP_ACQUIRE | XFRMGRP_EXPIRE;
	if (bind(this->socket, (struct sockaddr*)&addr, sizeof(addr)) != 0)
	{
		this->responses->destroy(this->responses);
		close(this->socket);
		free(this);
		charon->kill(charon, "Unable to bind netlink socket");	
	}
	
	if (pthread_create(&this->thread, NULL, (void*(*)(void*))receive_messages, this) != 0)
	{
		this->responses->destroy(this->responses);
		close(this->socket);
		free(this);
		charon->kill(charon, "Unable to create netlink thread");
	}
	
	return &this->public;
}