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#include <net/ip.h>
#include <net/tcp.h>
#include <net/netfilter/nf_tables.h>
#include <linux/netfilter/nfnetlink_osf.h>
struct nft_osf {
u8 dreg;
};
static const struct nla_policy nft_osf_policy[NFTA_OSF_MAX + 1] = {
[NFTA_OSF_DREG] = { .type = NLA_U32 },
};
static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
const struct nft_pktinfo *pkt)
{
struct nft_osf *priv = nft_expr_priv(expr);
u32 *dest = ®s->data[priv->dreg];
struct sk_buff *skb = pkt->skb;
const struct tcphdr *tcp;
struct tcphdr _tcph;
const char *os_name;
if (pkt->tprot != IPPROTO_TCP) {
regs->verdict.code = NFT_BREAK;
return;
}
tcp = skb_header_pointer(skb, ip_hdrlen(skb),
sizeof(struct tcphdr), &_tcph);
if (!tcp) {
regs->verdict.code = NFT_BREAK;
return;
}
if (!tcp->syn) {
regs->verdict.code = NFT_BREAK;
return;
}
os_name = nf_osf_find(skb, nf_osf_fingers);
if (!os_name)
strncpy((char *)dest, "unknown", NFT_OSF_MAXGENRELEN);
else
strncpy((char *)dest, os_name, NFT_OSF_MAXGENRELEN);
}
static int nft_osf_init(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nlattr * const tb[])
{
struct nft_osf *priv = nft_expr_priv(expr);
int err;
if (!tb[NFTA_OSF_DREG])
return -EINVAL;
err = nft_parse_register_store(ctx, tb[NFTA_OSF_DREG], &priv->dreg,
NULL, NFT_DATA_VALUE,
NFT_OSF_MAXGENRELEN);
if (err < 0)
return err;
return 0;
}
static int nft_osf_dump(struct sk_buff *skb, const struct nft_expr *expr)
{
const struct nft_osf *priv = nft_expr_priv(expr);
if (nft_dump_register(skb, NFTA_OSF_DREG, priv->dreg))
goto nla_put_failure;
return 0;
nla_put_failure:
return -1;
}
static int nft_osf_validate(const struct nft_ctx *ctx,
const struct nft_expr *expr,
const struct nft_data **data)
{
unsigned int hooks;
switch (ctx->family) {
case NFPROTO_IPV4:
case NFPROTO_IPV6:
case NFPROTO_INET:
hooks = (1 << NF_INET_LOCAL_IN) |
(1 << NF_INET_PRE_ROUTING) |
(1 << NF_INET_FORWARD);
break;
default:
return -EOPNOTSUPP;
}
return nft_chain_validate_hooks(ctx->chain, hooks);
}
static struct nft_expr_type nft_osf_type;
static const struct nft_expr_ops nft_osf_op = {
.eval = nft_osf_eval,
.size = NFT_EXPR_SIZE(sizeof(struct nft_osf)),
.init = nft_osf_init,
.dump = nft_osf_dump,
.type = &nft_osf_type,
.validate = nft_osf_validate,
};
static struct nft_expr_type nft_osf_type __read_mostly = {
.ops = &nft_osf_op,
.name = "osf",
.owner = THIS_MODULE,
.policy = nft_osf_policy,
.maxattr = NFTA_OSF_MAX,
};
static int __init nft_osf_module_init(void)
{
return nft_register_expr(&nft_osf_type);
}
static void __exit nft_osf_module_exit(void)
{
return nft_unregister_expr(&nft_osf_type);
}
module_init(nft_osf_module_init);
module_exit(nft_osf_module_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Fernando Fernandez <ffmancera@riseup.net>");
MODULE_ALIAS_NFT_EXPR("osf");
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