Commit 51c23b47 authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso
Browse files

netfilter: nf_osf: add nf_osf_find() 



This new function returns the OS genre as a string. Plan is to use to
from the new nft_osf extension.

Note that this doesn't yet support ttl options, but it could be easily
extended to do so.

Tested-by: default avatarFernando Fernandez Mancera <ffmancera@riseup.net>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent 222440b4

include/linux/netfilter/nf_osf.h

+9 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

#ifndef _NFOSF_H

#define _NFOSF_H



#include <uapi/linux/netfilter/nf_osf.h>



/* Initial window size option state machine: multiple of mss, mtu or
@@ -31,3 +35,8 @@ bool nf_osf_match(const struct sk_buff *skb, u_int8_t family, 
		  int hooknum, struct net_device *in, struct net_device *out,

		  const struct nf_osf_info *info, struct net *net,

		  const struct list_head *nf_osf_fingers);



const char *nf_osf_find(const struct sk_buff *skb,

                        const struct list_head *nf_osf_fingers);



#endif /* _NFOSF_H */

net/netfilter/nf_osf.c

+30 −0
Original line number Diff line number Diff line
@@ -249,4 +249,34 @@ nf_osf_match(const struct sk_buff *skb, u_int8_t family, 
}

EXPORT_SYMBOL_GPL(nf_osf_match);



const char *nf_osf_find(const struct sk_buff *skb,

			const struct list_head *nf_osf_fingers)

{

	const struct iphdr *ip = ip_hdr(skb);

	const struct nf_osf_user_finger *f;

	unsigned char opts[MAX_IPOPTLEN];

	const struct nf_osf_finger *kf;

	struct nf_osf_hdr_ctx ctx;

	const struct tcphdr *tcp;

	const char *genre = NULL;



	memset(&ctx, 0, sizeof(ctx));



	tcp = nf_osf_hdr_ctx_init(&ctx, skb, ip, opts);

	if (!tcp)

		return false;



	list_for_each_entry_rcu(kf, &nf_osf_fingers[ctx.df], finger_entry) {

		f = &kf->finger;

		if (!nf_osf_match_one(skb, f, -1, &ctx))

			continue;



		genre = f->genre;

		break;

	}



	return genre;

}

EXPORT_SYMBOL_GPL(nf_osf_find);



MODULE_LICENSE("GPL");