fwd.c

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * (C) 2015 Pablo Neira Ayuso <pablo@netfilter.org>
 */

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <arpa/inet.h>
#include <errno.h>
#include "internal.h"
#include <libmnl/libmnl.h>
#include <linux/netfilter/nf_tables.h>
#include <libnftnl/expr.h>
#include <libnftnl/rule.h>
#include "expr_ops.h"
#include "data_reg.h"

struct nftnl_expr_fwd {
        enum nft_registers      sreg_dev;
        enum nft_registers      sreg_addr;
        uint32_t                nfproto;
};

static int
nftnl_expr_fwd_set(struct nftnl_expr *e, uint16_t type,
                   const void *data, uint32_t data_len, uint32_t byteorder)
{
        struct nftnl_expr_fwd *fwd = nftnl_expr_data(e);

        switch (type) {
        case NFTNL_EXPR_FWD_SREG_DEV:
                memcpy(&fwd->sreg_dev, data, data_len);
                break;
        case NFTNL_EXPR_FWD_SREG_ADDR:
                memcpy(&fwd->sreg_addr, data, data_len);
                break;
        case NFTNL_EXPR_FWD_NFPROTO:
                memcpy(&fwd->nfproto, data, data_len);
                break;
        }
        return 0;
}

static const void *nftnl_expr_fwd_get(const struct nftnl_expr *e,
                                      uint16_t type, uint32_t *data_len)
{
        struct nftnl_expr_fwd *fwd = nftnl_expr_data(e);

        switch (type) {
        case NFTNL_EXPR_FWD_SREG_DEV:
                *data_len = sizeof(fwd->sreg_dev);
                return &fwd->sreg_dev;
        case NFTNL_EXPR_FWD_SREG_ADDR:
                *data_len = sizeof(fwd->sreg_addr);
                return &fwd->sreg_addr;
        case NFTNL_EXPR_FWD_NFPROTO:
                *data_len = sizeof(fwd->nfproto);
                return &fwd->nfproto;
        }
        return NULL;
}

static int nftnl_expr_fwd_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_FWD_MAX) < 0)
                return MNL_CB_OK;

        switch (type) {
        case NFTA_FWD_SREG_DEV:
        case NFTA_FWD_SREG_ADDR:
        case NFTA_FWD_NFPROTO:
                if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
                        abi_breakage();
                break;
        }

        tb[type] = attr;
        return MNL_CB_OK;
}

static void nftnl_expr_fwd_build(struct nlmsghdr *nlh,
                                 const struct nftnl_expr *e)
{
        struct nftnl_expr_fwd *fwd = nftnl_expr_data(e);

        if (e->flags & (1 << NFTNL_EXPR_FWD_SREG_DEV))
                mnl_attr_put_u32(nlh, NFTA_FWD_SREG_DEV, htonl(fwd->sreg_dev));
        if (e->flags & (1 << NFTNL_EXPR_FWD_SREG_ADDR))
                mnl_attr_put_u32(nlh, NFTA_FWD_SREG_ADDR, htonl(fwd->sreg_addr));
        if (e->flags & (1 << NFTNL_EXPR_FWD_NFPROTO))
                mnl_attr_put_u32(nlh, NFTA_FWD_NFPROTO, htonl(fwd->nfproto));
}

static int nftnl_expr_fwd_parse(struct nftnl_expr *e, struct nlattr *attr)
{
        struct nftnl_expr_fwd *fwd = nftnl_expr_data(e);
        struct nlattr *tb[NFTA_FWD_MAX + 1] = {};
        int ret = 0;

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

        if (tb[NFTA_FWD_SREG_DEV]) {
                fwd->sreg_dev = ntohl(mnl_attr_get_u32(tb[NFTA_FWD_SREG_DEV]));
                e->flags |= (1 << NFTNL_EXPR_FWD_SREG_DEV);
        }
        if (tb[NFTA_FWD_SREG_ADDR]) {
                fwd->sreg_addr = ntohl(mnl_attr_get_u32(tb[NFTA_FWD_SREG_ADDR]));
                e->flags |= (1 << NFTNL_EXPR_FWD_SREG_ADDR);
        }
        if (tb[NFTA_FWD_NFPROTO]) {
                fwd->nfproto = ntohl(mnl_attr_get_u32(tb[NFTA_FWD_NFPROTO]));
                e->flags |= (1 << NFTNL_EXPR_FWD_NFPROTO);
        }

        return ret;
}

static int nftnl_expr_fwd_snprintf(char *buf, size_t remain,
                                   uint32_t flags, const struct nftnl_expr *e)
{
        struct nftnl_expr_fwd *fwd = nftnl_expr_data(e);
        int offset = 0, ret;

        if (e->flags & (1 << NFTNL_EXPR_FWD_SREG_DEV)) {
                ret = snprintf(buf + offset, remain, "sreg_dev %u ",
                               fwd->sreg_dev);
                SNPRINTF_BUFFER_SIZE(ret, remain, offset);
        }
        if (e->flags & (1 << NFTNL_EXPR_FWD_SREG_ADDR)) {
                ret = snprintf(buf + offset, remain, "sreg_addr %u ",
                               fwd->sreg_addr);
                SNPRINTF_BUFFER_SIZE(ret, remain, offset);
        }
        if (e->flags & (1 << NFTNL_EXPR_FWD_NFPROTO)) {
                ret = snprintf(buf + offset, remain, "nfproto %u ",
                               fwd->nfproto);
                SNPRINTF_BUFFER_SIZE(ret, remain, offset);
        }

        return offset;
}

static struct attr_policy fwd_attr_policy[__NFTNL_EXPR_FWD_MAX] = {
        [NFTNL_EXPR_FWD_SREG_DEV]  = { .maxlen = sizeof(uint32_t) },
        [NFTNL_EXPR_FWD_SREG_ADDR] = { .maxlen = sizeof(uint32_t) },
        [NFTNL_EXPR_FWD_NFPROTO]   = { .maxlen = sizeof(uint32_t) },
};

struct expr_ops expr_ops_fwd = {
        .name           = "fwd",
        .alloc_len      = sizeof(struct nftnl_expr_fwd),
        .nftnl_max_attr = __NFTNL_EXPR_FWD_MAX - 1,
        .attr_policy    = fwd_attr_policy,
        .set            = nftnl_expr_fwd_set,
        .get            = nftnl_expr_fwd_get,
        .parse          = nftnl_expr_fwd_parse,
        .build          = nftnl_expr_fwd_build,
        .output         = nftnl_expr_fwd_snprintf,
};