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/*
* BIRD -- Manipulation the IPsec SA/SP database using setkey(8) utility
*
* (c) 2016 CZ.NIC z.s.p.o.
*/
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <net/pfkeyv2.h>
#include <netipsec/ipsec.h>
#include "nest/bird.h"
#include "lib/unix.h"
/*
* Open a socket for manage the IPsec SA/SP database entries
*/
static int
setkey_open_socket(void)
{
int s = socket(PF_KEY, SOCK_RAW, PF_KEY_V2);
if (s < 0)
{
log(L_ERR "SETKEY: socket: %m");
return -1;
}
return s;
}
static int
setkey_send(struct sadb_msg *msg, uint len)
{
int s = setkey_open_socket();
if (s < 0)
return -1;
if (msg->sadb_msg_type == SADB_ADD)
{
/* Delete possible current key in the IPsec SA/SP database */
msg->sadb_msg_type = SADB_DELETE;
send(s, msg, len, 0);
msg->sadb_msg_type = SADB_ADD;
}
if (send(s, msg, len, 0) < 0)
{
log(L_ERR "SETKEY: send: %m");
close(s);
return -1;
}
close(s);
return 0;
}
/*
* Perform setkey(8)-like operation for set the password for TCP MD5 Signature.
* Could be called with SABD_ADD or SADB_DELETE argument. Note that SADB_ADD
* argument is internally processed as a pair of SADB_ADD and SADB_DELETE
* operations to implement replace.
*/
static int
setkey_md5(sockaddr *src, sockaddr *dst, uint pxlen, char *passwd, uint type)
{
uint passwd_len = passwd ? strlen(passwd) : 0;
uint total =
sizeof(struct sadb_msg) +
sizeof(struct sadb_key) + PFKEY_ALIGN8(passwd_len) +
sizeof(struct sadb_sa) +
sizeof(struct sadb_x_sa2) +
sizeof(struct sadb_address) + PFKEY_ALIGN8(src->sa.sa_len) +
sizeof(struct sadb_address) + PFKEY_ALIGN8(dst->sa.sa_len);
char *buf = alloca(total);
char *pos = buf;
uint len;
memset(buf, 0, total);
struct sadb_msg *msg = (void *) pos;
len = sizeof(struct sadb_msg);
msg->sadb_msg_version = PF_KEY_V2;
msg->sadb_msg_type = type;
msg->sadb_msg_satype = SADB_X_SATYPE_TCPSIGNATURE;
msg->sadb_msg_len = 0; /* Fix it later */
msg->sadb_msg_pid = getpid();
pos += len;
/* Set authentication algorithm and password */
struct sadb_key *key = (void *) pos;
len = sizeof(struct sadb_key) + PFKEY_ALIGN8(passwd_len);
key->sadb_key_len = PFKEY_UNIT64(len);
key->sadb_key_exttype = SADB_EXT_KEY_AUTH;
key->sadb_key_bits = passwd_len * 8;
memcpy(pos + sizeof(struct sadb_key), passwd, passwd_len);
pos += len;
struct sadb_sa *sa = (void *) pos;
len = sizeof(struct sadb_sa);
sa->sadb_sa_len = PFKEY_UNIT64(len);
sa->sadb_sa_exttype = SADB_EXT_SA;
sa->sadb_sa_spi = htonl((u32) TCP_SIG_SPI);
sa->sadb_sa_auth = SADB_X_AALG_TCP_MD5;
sa->sadb_sa_encrypt = SADB_EALG_NONE;
sa->sadb_sa_flags = SADB_X_EXT_CYCSEQ;
pos += len;
struct sadb_x_sa2 *sa2 = (void *) pos;
len = sizeof(struct sadb_x_sa2);
sa2->sadb_x_sa2_len = PFKEY_UNIT64(len);
sa2->sadb_x_sa2_exttype = SADB_X_EXT_SA2;
sa2->sadb_x_sa2_mode = IPSEC_MODE_ANY;
pos += len;
/* Set source address */
struct sadb_address *saddr = (void *) pos;
len = sizeof(struct sadb_address) + PFKEY_ALIGN8(src->sa.sa_len);
saddr->sadb_address_len = PFKEY_UNIT64(len);
saddr->sadb_address_exttype = SADB_EXT_ADDRESS_SRC;
saddr->sadb_address_proto = IPSEC_ULPROTO_ANY;
saddr->sadb_address_prefixlen = pxlen;
memcpy(pos + sizeof(struct sadb_address), &src->sa, src->sa.sa_len);
pos += len;
/* Set destination address */
struct sadb_address *daddr = (void *) pos;
len = sizeof(struct sadb_address) + PFKEY_ALIGN8(dst->sa.sa_len);
daddr->sadb_address_len = PFKEY_UNIT64(len);
daddr->sadb_address_exttype = SADB_EXT_ADDRESS_DST;
daddr->sadb_address_proto = IPSEC_ULPROTO_ANY;
daddr->sadb_address_prefixlen = pxlen;
memcpy(pos + sizeof(struct sadb_address), &dst->sa, dst->sa.sa_len);
pos += len;
len = pos - buf;
msg->sadb_msg_len = PFKEY_UNIT64(len);
return setkey_send(msg, len);
}
/*
* Manipulation with the IPsec SA/SP database
*/
static int
sk_set_md5_in_sasp_db(sock *s, ip_addr local, ip_addr remote, struct iface *ifa, char *passwd)
{
sockaddr src, dst;
sockaddr_fill(&src, s->af, local, ifa, 0);
sockaddr_fill(&dst, s->af, remote, ifa, 0);
uint pxlen = (s->af == AF_INET) ? IP4_MAX_PREFIX_LENGTH : IP6_MAX_PREFIX_LENGTH;
if (passwd && *passwd)
{
int len = strlen(passwd);
if (len > TCP_KEYLEN_MAX)
ERR_MSG("The password for TCP MD5 Signature is too long");
if (setkey_md5(&src, &dst, pxlen, passwd, SADB_ADD) < 0)
ERR_MSG("Cannot add TCP-MD5 password into the IPsec SA/SP database");
}
else
{
if (setkey_md5(&src, &dst, pxlen, NULL, SADB_DELETE) < 0)
ERR_MSG("Cannot delete TCP-MD5 password from the IPsec SA/SP database");
}
return 0;
}
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