/*      $OpenBSD: pfkey.c,v 1.13 2022/11/07 22:39:13 mbuhl Exp $ */

/*
 * Copyright (c) 2003, 2004 Henning Brauer <henning@openbsd.org>
 * Copyright (c) 2003, 2004 Markus Friedl <markus@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "ldpd.h"
#include "ldpe.h"
#include "log.h"

static int       pfkey_send(int, uint8_t, uint8_t, uint8_t,
                    int, union ldpd_addr *, union ldpd_addr *,
                    uint32_t, uint8_t, int, char *, uint8_t, int, char *,
                    uint16_t, uint16_t);
static int       pfkey_reply(int, uint32_t *);
static int       pfkey_sa_add(int, union ldpd_addr *, union ldpd_addr *,
                    uint8_t, char *, uint32_t *);
static int       pfkey_sa_remove(int, union ldpd_addr *, union ldpd_addr *,
                    uint32_t *);
static int       pfkey_md5sig_establish(struct nbr *, struct ldp_auth *);
static int       pfkey_md5sig_remove(struct nbr *);

#define PFKEY2_CHUNK sizeof(uint64_t)
#define ROUNDUP(x) (((x) + (PFKEY2_CHUNK - 1)) & ~(PFKEY2_CHUNK - 1))
#define IOV_CNT 20

static uint32_t  sadb_msg_seq;
static uint32_t  pid; /* should pid_t but pfkey needs uint32_t */
static int       fd;

static int
pfkey_send(int sd, uint8_t satype, uint8_t mtype, uint8_t dir,
    int af, union ldpd_addr *src, union ldpd_addr *dst, uint32_t spi,
    uint8_t aalg, int alen, char *akey, uint8_t ealg, int elen, char *ekey,
    uint16_t sport, uint16_t dport)
{
        struct sadb_msg         smsg;
        struct sadb_sa          sa;
        struct sadb_address     sa_src, sa_dst;
        struct sadb_key         sa_akey, sa_ekey;
        struct sadb_spirange    sa_spirange;
        struct iovec            iov[IOV_CNT];
        ssize_t                 n;
        int                     len = 0;
        int                     iov_cnt;
        struct sockaddr_storage ssrc, sdst, smask, dmask;
        struct sockaddr         *saptr;

        if (!pid)
                pid = getpid();

        /* we need clean sockaddr... no ports set */
        memset(&ssrc, 0, sizeof(ssrc));
        memset(&smask, 0, sizeof(smask));
        if ((saptr = addr2sa(af, src, 0)))
                memcpy(&ssrc, saptr, sizeof(ssrc));
        switch (af) {
        case AF_INET:
                memset(&((struct sockaddr_in *)&smask)->sin_addr, 0xff, 32/8);
                break;
        case AF_INET6:
                memset(&((struct sockaddr_in6 *)&smask)->sin6_addr, 0xff,
                    128/8);
                break;
        default:
                return (-1);
        }
        smask.ss_family = ssrc.ss_family;
        smask.ss_len = ssrc.ss_len;

        memset(&sdst, 0, sizeof(sdst));
        memset(&dmask, 0, sizeof(dmask));
        if ((saptr = addr2sa(af, dst, 0)))
                memcpy(&sdst, saptr, sizeof(sdst));
        switch (af) {
        case AF_INET:
                memset(&((struct sockaddr_in *)&dmask)->sin_addr, 0xff, 32/8);
                break;
        case AF_INET6:
                memset(&((struct sockaddr_in6 *)&dmask)->sin6_addr, 0xff,
                    128/8);
                break;
        default:
                return (-1);
        }
        dmask.ss_family = sdst.ss_family;
        dmask.ss_len = sdst.ss_len;

        memset(&smsg, 0, sizeof(smsg));
        smsg.sadb_msg_version = PF_KEY_V2;
        smsg.sadb_msg_seq = ++sadb_msg_seq;
        smsg.sadb_msg_pid = pid;
        smsg.sadb_msg_len = sizeof(smsg) / 8;
        smsg.sadb_msg_type = mtype;
        smsg.sadb_msg_satype = satype;

        switch (mtype) {
        case SADB_GETSPI:
                memset(&sa_spirange, 0, sizeof(sa_spirange));
                sa_spirange.sadb_spirange_exttype = SADB_EXT_SPIRANGE;
                sa_spirange.sadb_spirange_len = sizeof(sa_spirange) / 8;
                sa_spirange.sadb_spirange_min = 0x100;
                sa_spirange.sadb_spirange_max = 0xffffffff;
                sa_spirange.sadb_spirange_reserved = 0;
                break;
        case SADB_ADD:
        case SADB_UPDATE:
        case SADB_DELETE:
                memset(&sa, 0, sizeof(sa));
                sa.sadb_sa_exttype = SADB_EXT_SA;
                sa.sadb_sa_len = sizeof(sa) / 8;
                sa.sadb_sa_replay = 0;
                sa.sadb_sa_spi = spi;
                sa.sadb_sa_state = SADB_SASTATE_MATURE;
                break;
        }

        memset(&sa_src, 0, sizeof(sa_src));
        sa_src.sadb_address_exttype = SADB_EXT_ADDRESS_SRC;
        sa_src.sadb_address_len = (sizeof(sa_src) + ROUNDUP(ssrc.ss_len)) / 8;

        memset(&sa_dst, 0, sizeof(sa_dst));
        sa_dst.sadb_address_exttype = SADB_EXT_ADDRESS_DST;
        sa_dst.sadb_address_len = (sizeof(sa_dst) + ROUNDUP(sdst.ss_len)) / 8;

        sa.sadb_sa_auth = aalg;
        sa.sadb_sa_encrypt = SADB_X_EALG_AES; /* XXX */

        switch (mtype) {
        case SADB_ADD:
        case SADB_UPDATE:
                memset(&sa_akey, 0, sizeof(sa_akey));
                sa_akey.sadb_key_exttype = SADB_EXT_KEY_AUTH;
                sa_akey.sadb_key_len = (sizeof(sa_akey) +
                    ((alen + 7) / 8) * 8) / 8;
                sa_akey.sadb_key_bits = 8 * alen;

                memset(&sa_ekey, 0, sizeof(sa_ekey));
                sa_ekey.sadb_key_exttype = SADB_EXT_KEY_ENCRYPT;
                sa_ekey.sadb_key_len = (sizeof(sa_ekey) +
                    ((elen + 7) / 8) * 8) / 8;
                sa_ekey.sadb_key_bits = 8 * elen;

                break;
        }

        iov_cnt = 0;

        /* msghdr */
        iov[iov_cnt].iov_base = &smsg;
        iov[iov_cnt].iov_len = sizeof(smsg);
        iov_cnt++;

        switch (mtype) {
        case SADB_ADD:
        case SADB_UPDATE:
        case SADB_DELETE:
                /* SA hdr */
                iov[iov_cnt].iov_base = &sa;
                iov[iov_cnt].iov_len = sizeof(sa);
                smsg.sadb_msg_len += sa.sadb_sa_len;
                iov_cnt++;
                break;
        case SADB_GETSPI:
                /* SPI range */
                iov[iov_cnt].iov_base = &sa_spirange;
                iov[iov_cnt].iov_len = sizeof(sa_spirange);
                smsg.sadb_msg_len += sa_spirange.sadb_spirange_len;
                iov_cnt++;
                break;
        }

        /* dest addr */
        iov[iov_cnt].iov_base = &sa_dst;
        iov[iov_cnt].iov_len = sizeof(sa_dst);
        iov_cnt++;
        iov[iov_cnt].iov_base = &sdst;
        iov[iov_cnt].iov_len = ROUNDUP(sdst.ss_len);
        smsg.sadb_msg_len += sa_dst.sadb_address_len;
        iov_cnt++;

        /* src addr */
        iov[iov_cnt].iov_base = &sa_src;
        iov[iov_cnt].iov_len = sizeof(sa_src);
        iov_cnt++;
        iov[iov_cnt].iov_base = &ssrc;
        iov[iov_cnt].iov_len = ROUNDUP(ssrc.ss_len);
        smsg.sadb_msg_len += sa_src.sadb_address_len;
        iov_cnt++;

        switch (mtype) {
        case SADB_ADD:
        case SADB_UPDATE:
                if (alen) {
                        /* auth key */
                        iov[iov_cnt].iov_base = &sa_akey;
                        iov[iov_cnt].iov_len = sizeof(sa_akey);
                        iov_cnt++;
                        iov[iov_cnt].iov_base = akey;
                        iov[iov_cnt].iov_len = ((alen + 7) / 8) * 8;
                        smsg.sadb_msg_len += sa_akey.sadb_key_len;
                        iov_cnt++;
                }
                if (elen) {
                        /* encryption key */
                        iov[iov_cnt].iov_base = &sa_ekey;
                        iov[iov_cnt].iov_len = sizeof(sa_ekey);
                        iov_cnt++;
                        iov[iov_cnt].iov_base = ekey;
                        iov[iov_cnt].iov_len = ((elen + 7) / 8) * 8;
                        smsg.sadb_msg_len += sa_ekey.sadb_key_len;
                        iov_cnt++;
                }
                break;
        }

        len = smsg.sadb_msg_len * 8;
        do {
                n = writev(sd, iov, iov_cnt);
        } while (n == -1 && (errno == EAGAIN || errno == EINTR));

        if (n == -1) {
                log_warn("writev (%d/%d)", iov_cnt, len);
                return (-1);
        }

        return (0);
}

int
pfkey_read(int sd, struct sadb_msg *h)
{
        struct sadb_msg hdr;

        if (recv(sd, &hdr, sizeof(hdr), MSG_PEEK) != sizeof(hdr)) {
                if (errno == EAGAIN || errno == EINTR)
                        return (1);
                log_warn("pfkey peek");
                return (-1);
        }

        /* XXX: Only one message can be outstanding. */
        if (hdr.sadb_msg_seq == sadb_msg_seq &&
            hdr.sadb_msg_pid == pid) {
                if (h)
                        *h = hdr;
                return (0);
        }

        /* not ours, discard */
        if (read(sd, &hdr, sizeof(hdr)) == -1) {
                if (errno == EAGAIN || errno == EINTR)
                        return (1);
                log_warn("pfkey read");
                return (-1);
        }

        return (1);
}

static int
pfkey_reply(int sd, uint32_t *spip)
{
        struct sadb_msg hdr, *msg;
        struct sadb_ext *ext;
        struct sadb_sa *sa;
        uint8_t *data;
        ssize_t len;
        int rv;

        do {
                rv = pfkey_read(sd, &hdr);
                if (rv == -1)
                        return (-1);
        } while (rv);

        if (hdr.sadb_msg_errno != 0) {
                errno = hdr.sadb_msg_errno;
                if (errno == ESRCH)
                        return (0);
                else {
                        log_warn("pfkey");
                        return (-1);
                }
        }
        if ((data = reallocarray(NULL, hdr.sadb_msg_len, PFKEY2_CHUNK)) == NULL) {
                log_warn("pfkey malloc");
                return (-1);
        }
        len = hdr.sadb_msg_len * PFKEY2_CHUNK;
        if (read(sd, data, len) != len) {
                log_warn("pfkey read");
                freezero(data, len);
                return (-1);
        }

        if (hdr.sadb_msg_type == SADB_GETSPI) {
                if (spip == NULL) {
                        freezero(data, len);
                        return (0);
                }

                msg = (struct sadb_msg *)data;
                for (ext = (struct sadb_ext *)(msg + 1);
                    (size_t)((uint8_t *)ext - (uint8_t *)msg) <
                    msg->sadb_msg_len * PFKEY2_CHUNK;
                    ext = (struct sadb_ext *)((uint8_t *)ext +
                    ext->sadb_ext_len * PFKEY2_CHUNK)) {
                        if (ext->sadb_ext_type == SADB_EXT_SA) {
                                sa = (struct sadb_sa *) ext;
                                *spip = sa->sadb_sa_spi;
                                break;
                        }
                }
        }
        freezero(data, len);
        return (0);
}

static int
pfkey_sa_add(int af, union ldpd_addr *src, union ldpd_addr *dst, uint8_t keylen,
    char *key, uint32_t *spi)
{
        if (pfkey_send(fd, SADB_X_SATYPE_TCPSIGNATURE, SADB_GETSPI, 0,
            af, src, dst, 0, 0, 0, NULL, 0, 0, NULL, 0, 0) < 0)
                return (-1);
        if (pfkey_reply(fd, spi) < 0)
                return (-1);
        if (pfkey_send(fd, SADB_X_SATYPE_TCPSIGNATURE, SADB_UPDATE, 0,
            af, src, dst, *spi, 0, keylen, key, 0, 0, NULL, 0, 0) < 0)
                return (-1);
        if (pfkey_reply(fd, NULL) < 0)
                return (-1);
        return (0);
}

static int
pfkey_sa_remove(int af, union ldpd_addr *src, union ldpd_addr *dst,
    uint32_t *spi)
{
        if (pfkey_send(fd, SADB_X_SATYPE_TCPSIGNATURE, SADB_DELETE, 0,
            af, src, dst, *spi, 0, 0, NULL, 0, 0, NULL, 0, 0) < 0)
                return (-1);
        if (pfkey_reply(fd, NULL) < 0)
                return (-1);
        *spi = 0;
        return (0);
}

static int
pfkey_md5sig_establish(struct nbr *nbr, struct ldp_auth *auth)
{
        sleep(1);

        pfkey_md5sig_remove(nbr);

        if (pfkey_sa_add(nbr->af, &nbr->laddr, &nbr->raddr,
            auth->md5key_len, auth->md5key, &nbr->auth_spi_out) == -1)
                return (-1);

        if (pfkey_sa_add(nbr->af, &nbr->raddr, &nbr->laddr,
            auth->md5key_len, auth->md5key, &nbr->auth_spi_in) == -1)
                return (-1);

        nbr->auth_established = 1;

        return (0);
}

static int
pfkey_md5sig_remove(struct nbr *nbr)
{
        if (nbr->auth_spi_out) {
                if (pfkey_sa_remove(nbr->af, &nbr->laddr, &nbr->raddr,
                    &nbr->auth_spi_out) == -1)
                        return (-1);
        }
        if (nbr->auth_spi_in) {
                if (pfkey_sa_remove(nbr->af, &nbr->raddr, &nbr->laddr,
                    &nbr->auth_spi_in) == -1)
                        return (-1);
        }

        nbr->auth_established = 0;
        nbr->auth_spi_in = 0;
        nbr->auth_spi_out = 0;

        return (0);
}

static struct ldp_auth *
pfkey_find_auth(struct ldpd_conf *conf, struct nbr *nbr)
{
        struct ldp_auth *auth, *match = NULL;

        LIST_FOREACH(auth, &conf->auth_list, entry) {
                in_addr_t mask = prefixlen2mask(auth->idlen);
                if ((auth->id.s_addr & mask) != (nbr->id.s_addr & mask))
                        continue;

                if (match == NULL ||
                    match->idlen < auth->idlen)
                        match = auth;
        }

        return (match);
}

int
pfkey_establish(struct ldpd_conf *conf, struct nbr *nbr)
{
        struct ldp_auth *auth = NULL;

        auth = pfkey_find_auth(conf, nbr);
        if (auth == NULL || /* no policy */
            auth->md5key_len == 0) /* "no tcpmd5 sig" */
                return (0);
        
        return (pfkey_md5sig_establish(nbr, auth));
}

int
pfkey_remove(struct nbr *nbr)
{
        return (pfkey_md5sig_remove(nbr));
}

int
pfkey_init(void)
{
        if ((fd = socket(PF_KEY, SOCK_RAW | SOCK_CLOEXEC | SOCK_NONBLOCK,
            PF_KEY_V2)) == -1) {
                if (errno == EPROTONOSUPPORT) {
                        log_warnx("PF_KEY not available");
                        sysdep.no_pfkey = 1;
                        return (-1);
                } else
                        fatal("pfkey setup failed");
        }
        return (fd);
}