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netfilter: nft_osf: Add ttl option support

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

Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Fernando Fernandez Mancera 2018-10-10 09:57:13 +02:00 committed by Pablo Neira Ayuso
parent ea9cf2a55a
commit a218dc82f0
4 changed files with 42 additions and 25 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

3
include/linux/netfilter/nfnetlink_osf.h
View file

@ -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 */

7
include/uapi/linux/netfilter/nf_tables.h
View file

@ -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)

42
net/netfilter/nfnetlink_osf.c
View file

@ -30,32 +30,27 @@ 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;
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;
for_ifa(in_dev) {
if (inet_ifa_match(ip->saddr, ifa)) {
ret = (ip->ttl == f_ttl);
break;
}
}
endfor_ifa(in_dev);
return ret;
for_ifa(in_dev) {
if (inet_ifa_match(ip->saddr, ifa)) {
ret = (ip->ttl == f_ttl);
break;
}
}
return ip->ttl == f_ttl;
endfor_ifa(in_dev);
return ret;
}
struct nf_osf_hdr_ctx {
@ -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;

15
net/netfilter/nft_osf.c
View file

@ -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;