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netfilter: conntrack: remove error callback and handle icmp from core 

icmp(v6) are the only two layer four protocols that need the error()
callback (to handle icmp errors that are related to an established
connections, e.g. packet too big, port unreachable and the like).

Remove the error callback and handle these two special cases from the core.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2018-09-12 15:19:11 +02:00 committed by Pablo Neira Ayuso
parent 0150ffbac7
commit 6fe78fa484
4 changed files with 52 additions and 22 deletions
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13
include/net/netfilter/nf_conntrack_l4proto.h
View File

@ -51,10 +51,6 @@ struct nf_conntrack_l4proto {
/* Called when a conntrack entry is destroyed */
void (*destroy)(struct nf_conn *ct);
int (*error)(struct nf_conn *tmpl, struct sk_buff *skb,
unsigned int dataoff,
const struct nf_hook_state *state);
/* called by gc worker if table is full */
bool (*can_early_drop)(const struct nf_conn *ct);
@ -97,6 +93,15 @@ struct nf_conntrack_l4proto {
struct module *me;
};
int nf_conntrack_icmpv4_error(struct nf_conn *tmpl,
struct sk_buff *skb,
unsigned int dataoff,
const struct nf_hook_state *state);
int nf_conntrack_icmpv6_error(struct nf_conn *tmpl,
struct sk_buff *skb,
unsigned int dataoff,
const struct nf_hook_state *state);
/* Existing built-in generic protocol */
extern const struct nf_conntrack_l4proto nf_conntrack_l4proto_generic;

43
net/netfilter/nf_conntrack_core.c
View File

@ -1486,6 +1486,39 @@ resolve_normal_ct(struct nf_conn *tmpl,
return 0;
}
/*
* icmp packets need special treatment to handle error messages that are
* related to a connection.
*
* Callers need to check if skb has a conntrack assigned when this
* helper returns; in such case skb belongs to an already known connection.
*/
static unsigned int __cold
nf_conntrack_handle_icmp(struct nf_conn *tmpl,
struct sk_buff *skb,
unsigned int dataoff,
u8 protonum,
const struct nf_hook_state *state)
{
int ret;
if (state->pf == NFPROTO_IPV4 && protonum == IPPROTO_ICMP)
ret = nf_conntrack_icmpv4_error(tmpl, skb, dataoff, state);
#if IS_ENABLED(CONFIG_IPV6)
else if (state->pf == NFPROTO_IPV6 && protonum == IPPROTO_ICMPV6)
ret = nf_conntrack_icmpv6_error(tmpl, skb, dataoff, state);
#endif
else
return NF_ACCEPT;
if (ret <= 0) {
NF_CT_STAT_INC_ATOMIC(state->net, error);
NF_CT_STAT_INC_ATOMIC(state->net, invalid);
}
return ret;
}
unsigned int
nf_conntrack_in(struct sk_buff *skb, const struct nf_hook_state *state)
{
@ -1518,14 +1551,10 @@ nf_conntrack_in(struct sk_buff *skb, const struct nf_hook_state *state)
l4proto = __nf_ct_l4proto_find(state->pf, protonum);
/* It may be an special packet, error, unclean...
* inverse of the return code tells to the netfilter
* core what to do with the packet. */
if (l4proto->error != NULL) {
ret = l4proto->error(tmpl, skb, dataoff, state);
if (protonum == IPPROTO_ICMP || protonum == IPPROTO_ICMPV6) {
ret = nf_conntrack_handle_icmp(tmpl, skb, dataoff,
protonum, state);
if (ret <= 0) {
NF_CT_STAT_INC_ATOMIC(state->net, error);
NF_CT_STAT_INC_ATOMIC(state->net, invalid);
ret = -ret;
goto out;
}

8
net/netfilter/nf_conntrack_proto_icmp.c
View File

@ -165,10 +165,9 @@ static void icmp_error_log(const struct sk_buff *skb,
}
/* Small and modified version of icmp_rcv */
static int
icmp_error(struct nf_conn *tmpl,
struct sk_buff *skb, unsigned int dataoff,
const struct nf_hook_state *state)
int nf_conntrack_icmpv4_error(struct nf_conn *tmpl,
struct sk_buff *skb, unsigned int dataoff,
const struct nf_hook_state *state)
{
const struct icmphdr *icmph;
struct icmphdr _ih;
@ -355,7 +354,6 @@ const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmp =
.pkt_to_tuple = icmp_pkt_to_tuple,
.invert_tuple = icmp_invert_tuple,
.packet = icmp_packet,
.error = icmp_error,
.destroy = NULL,
.me = NULL,
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)

10
net/netfilter/nf_conntrack_proto_icmpv6.c
View File

@ -184,11 +184,10 @@ static void icmpv6_error_log(const struct sk_buff *skb,
IPPROTO_ICMPV6, "%s", msg);
}
static int
icmpv6_error(struct nf_conn *tmpl,
struct sk_buff *skb,
unsigned int dataoff,
const struct nf_hook_state *state)
int nf_conntrack_icmpv6_error(struct nf_conn *tmpl,
struct sk_buff *skb,
unsigned int dataoff,
const struct nf_hook_state *state)
{
const struct icmp6hdr *icmp6h;
struct icmp6hdr _ih;
@ -366,7 +365,6 @@ const struct nf_conntrack_l4proto nf_conntrack_l4proto_icmpv6 =
.pkt_to_tuple = icmpv6_pkt_to_tuple,
.invert_tuple = icmpv6_invert_tuple,
.packet = icmpv6_packet,
.error = icmpv6_error,
#if IS_ENABLED(CONFIG_NF_CT_NETLINK)
.tuple_to_nlattr = icmpv6_tuple_to_nlattr,
.nlattr_tuple_size = icmpv6_nlattr_tuple_size,