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Commit a218dc82 authored by Fernando Fernandez Mancera's avatar Fernando Fernandez Mancera Committed by Pablo Neira Ayuso
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netfilter: nft_osf: Add ttl option support 



Add ttl option support to the nftables "osf" expression.

Signed-off-by: default avatarFernando Fernandez Mancera <ffmancera@riseup.net>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent ea9cf2a5

include/linux/netfilter/nfnetlink_osf.h

+2 −1
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ bool nf_osf_match(const struct sk_buff *skb, u_int8_t family, 
		  const struct list_head *nf_osf_fingers);



const char *nf_osf_find(const struct sk_buff *skb,

                        const struct list_head *nf_osf_fingers);

			const struct list_head *nf_osf_fingers,

			const int ttl_check);



#endif /* _NFOSF_H */

include/uapi/linux/netfilter/nf_tables.h

+7 −0
Original line number Diff line number Diff line
@@ -1511,9 +1511,16 @@ enum nft_flowtable_hook_attributes { 
};

#define NFTA_FLOWTABLE_HOOK_MAX	(__NFTA_FLOWTABLE_HOOK_MAX - 1)



/**

 * enum nft_osf_attributes - nftables osf expression netlink attributes

 *

 * @NFTA_OSF_DREG: destination register (NLA_U32: nft_registers)

 * @NFTA_OSF_TTL: Value of the TTL osf option (NLA_U8)

 */

enum nft_osf_attributes {

	NFTA_OSF_UNSPEC,

	NFTA_OSF_DREG,

	NFTA_OSF_TTL,

	__NFTA_OSF_MAX,

};

#define NFTA_OSF_MAX (__NFTA_OSF_MAX - 1)

net/netfilter/nfnetlink_osf.c

+21 −25
Original line number Diff line number Diff line
@@ -30,18 +30,16 @@ EXPORT_SYMBOL_GPL(nf_osf_fingers); 
static inline int nf_osf_ttl(const struct sk_buff *skb,

			     int ttl_check, unsigned char f_ttl)

{

	struct in_device *in_dev = __in_dev_get_rcu(skb->dev);

	const struct iphdr *ip = ip_hdr(skb);

	int ret = 0;



	if (ttl_check != -1) {

	if (ttl_check == NF_OSF_TTL_TRUE)

		return ip->ttl == f_ttl;

	if (ttl_check == NF_OSF_TTL_NOCHECK)

		return 1;

	else if (ip->ttl <= f_ttl)

		return 1;

		else {

			struct in_device *in_dev = __in_dev_get_rcu(skb->dev);

			int ret = 0;



	for_ifa(in_dev) {

		if (inet_ifa_match(ip->saddr, ifa)) {
@@ -49,14 +47,11 @@ static inline int nf_osf_ttl(const struct sk_buff *skb, 
			break;

		}

	}



	endfor_ifa(in_dev);



	return ret;

}

	}



	return ip->ttl == f_ttl;

}



struct nf_osf_hdr_ctx {

	bool			df;
@@ -213,7 +208,7 @@ nf_osf_match(const struct sk_buff *skb, u_int8_t family, 
	if (!tcp)

		return false;



	ttl_check = (info->flags & NF_OSF_TTL) ? info->ttl : -1;

	ttl_check = (info->flags & NF_OSF_TTL) ? info->ttl : 0;



	list_for_each_entry_rcu(kf, &nf_osf_fingers[ctx.df], finger_entry) {
@@ -257,7 +252,8 @@ 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 list_head *nf_osf_fingers,

			const int ttl_check)

{

	const struct iphdr *ip = ip_hdr(skb);

	const struct nf_osf_user_finger *f;
@@ -275,7 +271,7 @@ const char *nf_osf_find(const struct sk_buff *skb, 


	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))

		if (!nf_osf_match_one(skb, f, ttl_check, &ctx))

			continue;



		genre = f->genre;

net/netfilter/nft_osf.c

+14 −1
Original line number Diff line number Diff line
@@ -6,10 +6,12 @@ 


struct nft_osf {

	enum nft_registers	dreg:8;

	u8			ttl;

};



static const struct nla_policy nft_osf_policy[NFTA_OSF_MAX + 1] = {

	[NFTA_OSF_DREG]		= { .type = NLA_U32 },

	[NFTA_OSF_TTL]		= { .type = NLA_U8 },

};



static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs,
@@ -33,7 +35,7 @@ static void nft_osf_eval(const struct nft_expr *expr, struct nft_regs *regs, 
		return;

	}



	os_name = nf_osf_find(skb, nf_osf_fingers);

	os_name = nf_osf_find(skb, nf_osf_fingers, priv->ttl);

	if (!os_name)

		strncpy((char *)dest, "unknown", NFT_OSF_MAXGENRELEN);

	else
@@ -46,6 +48,14 @@ static int nft_osf_init(const struct nft_ctx *ctx, 
{

	struct nft_osf *priv = nft_expr_priv(expr);

	int err;

	u8 ttl;



	if (nla_get_u8(tb[NFTA_OSF_TTL])) {

		ttl = nla_get_u8(tb[NFTA_OSF_TTL]);

		if (ttl > 2)

			return -EINVAL;

		priv->ttl = ttl;

	}



	priv->dreg = nft_parse_register(tb[NFTA_OSF_DREG]);

	err = nft_validate_register_store(ctx, priv->dreg, NULL,
@@ -60,6 +70,9 @@ static int nft_osf_dump(struct sk_buff *skb, const struct nft_expr *expr) 
{

	const struct nft_osf *priv = nft_expr_priv(expr);



	if (nla_put_u8(skb, NFTA_OSF_TTL, priv->ttl))

		goto nla_put_failure;



	if (nft_dump_register(skb, NFTA_OSF_DREG, priv->dreg))

		goto nla_put_failure;