expr/tunnel.c

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * (C) 2018 by Pablo Neira Ayuso <pablo@netfilter.org>
 */

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <arpa/inet.h>
#include <errno.h>
#include <linux/netfilter/nf_tables.h>

#include "internal.h"
#include <libmnl/libmnl.h>
#include <libnftnl/expr.h>
#include <libnftnl/rule.h>

struct nftnl_expr_tunnel {
        enum nft_tunnel_keys    key;
        enum nft_registers      dreg;
};

static int
nftnl_expr_tunnel_set(struct nftnl_expr *e, uint16_t type,
                      const void *data, uint32_t data_len, uint32_t byteorder)
{
        struct nftnl_expr_tunnel *tunnel = nftnl_expr_data(e);

        switch(type) {
        case NFTNL_EXPR_TUNNEL_KEY:
                memcpy(&tunnel->key, data, data_len);
                break;
        case NFTNL_EXPR_TUNNEL_DREG:
                memcpy(&tunnel->dreg, data, data_len);
                break;
        }
        return 0;
}

static const void *
nftnl_expr_tunnel_get(const struct nftnl_expr *e, uint16_t type,
                       uint32_t *data_len)
{
        struct nftnl_expr_tunnel *tunnel = nftnl_expr_data(e);

        switch(type) {
        case NFTNL_EXPR_TUNNEL_KEY:
                *data_len = sizeof(tunnel->key);
                return &tunnel->key;
        case NFTNL_EXPR_TUNNEL_DREG:
                *data_len = sizeof(tunnel->dreg);
                return &tunnel->dreg;
        }
        return NULL;
}

static int nftnl_expr_tunnel_cb(const struct nlattr *attr, void *data)
{
        const struct nlattr **tb = data;
        int type = mnl_attr_get_type(attr);

        if (mnl_attr_type_valid(attr, NFTA_TUNNEL_MAX) < 0)
                return MNL_CB_OK;

        switch(type) {
        case NFTA_TUNNEL_KEY:
        case NFTA_TUNNEL_DREG:
                if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
                        abi_breakage();
                break;
        }

        tb[type] = attr;
        return MNL_CB_OK;
}

static void
nftnl_expr_tunnel_build(struct nlmsghdr *nlh, const struct nftnl_expr *e)
{
        struct nftnl_expr_tunnel *tunnel = nftnl_expr_data(e);

        if (e->flags & (1 << NFTNL_EXPR_TUNNEL_KEY))
                mnl_attr_put_u32(nlh, NFTA_TUNNEL_KEY, htonl(tunnel->key));
        if (e->flags & (1 << NFTNL_EXPR_TUNNEL_DREG))
                mnl_attr_put_u32(nlh, NFTA_TUNNEL_DREG, htonl(tunnel->dreg));
}

static int
nftnl_expr_tunnel_parse(struct nftnl_expr *e, struct nlattr *attr)
{
        struct nftnl_expr_tunnel *tunnel = nftnl_expr_data(e);
        struct nlattr *tb[NFTA_TUNNEL_MAX + 1] = {};

        if (mnl_attr_parse_nested(attr, nftnl_expr_tunnel_cb, tb) < 0)
                return -1;

        if (tb[NFTA_TUNNEL_KEY]) {
                tunnel->key = ntohl(mnl_attr_get_u32(tb[NFTA_TUNNEL_KEY]));
                e->flags |= (1 << NFTNL_EXPR_TUNNEL_KEY);
        }
        if (tb[NFTA_TUNNEL_DREG]) {
                tunnel->dreg = ntohl(mnl_attr_get_u32(tb[NFTA_TUNNEL_DREG]));
                e->flags |= (1 << NFTNL_EXPR_TUNNEL_DREG);
        }

        return 0;
}

static const char *tunnel_key2str_array[NFT_TUNNEL_MAX + 1] = {
        [NFT_TUNNEL_PATH]       = "path",
        [NFT_TUNNEL_ID]         = "id",
};

static const char *tunnel_key2str(uint8_t key)
{
        if (key <= NFT_TUNNEL_MAX)
                return tunnel_key2str_array[key];

        return "unknown";
}

static int
nftnl_expr_tunnel_snprintf(char *buf, size_t len,
                         uint32_t flags, const struct nftnl_expr *e)
{
        struct nftnl_expr_tunnel *tunnel = nftnl_expr_data(e);

        if (e->flags & (1 << NFTNL_EXPR_TUNNEL_DREG)) {
                return snprintf(buf, len, "load %s => reg %u ",
                                tunnel_key2str(tunnel->key), tunnel->dreg);
        }
        return 0;
}

static struct attr_policy tunnel_attr_policy[__NFTNL_EXPR_TUNNEL_MAX] = {
        [NFTNL_EXPR_TUNNEL_KEY]  = { .maxlen = sizeof(uint32_t) },
        [NFTNL_EXPR_TUNNEL_DREG] = { .maxlen = sizeof(uint32_t) },
};

struct expr_ops expr_ops_tunnel = {
        .name           = "tunnel",
        .alloc_len      = sizeof(struct nftnl_expr_tunnel),
        .nftnl_max_attr = __NFTNL_EXPR_TUNNEL_MAX - 1,
        .attr_policy    = tunnel_attr_policy,
        .set            = nftnl_expr_tunnel_set,
        .get            = nftnl_expr_tunnel_get,
        .parse          = nftnl_expr_tunnel_parse,
        .build          = nftnl_expr_tunnel_build,
        .output         = nftnl_expr_tunnel_snprintf,
};