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netfilter: move nf_send_resetX() code to nf_reject_ipvX modules

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Move nf_send_reset() and nf_send_reset6() to nf_reject_ipv4 and
nf_reject_ipv6 respectively. This code is shared by x_tables and
nf_tables.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Pablo Neira Ayuso 2014-09-26 14:35:15 +02:00
commit c8d7b98bec
7 changed files with 309 additions and 117 deletions
Download patch file Download diff file Expand all files Collapse all files

118
include/net/netfilter/ipv4/nf_reject.h
View file

@ -1,10 +1,6 @@
#ifndef _IPV4_NF_REJECT_H
#define _IPV4_NF_REJECT_H
#include <net/ip.h>
#include <net/tcp.h>
#include <net/route.h>
#include <net/dst.h>
#include <net/icmp.h>
static inline void nf_send_unreach(struct sk_buff *skb_in, int code)
@ -12,118 +8,6 @@ static inline void nf_send_unreach(struct sk_buff *skb_in, int code)
icmp_send(skb_in, ICMP_DEST_UNREACH, code, 0);
}
/* Send RST reply */
static void nf_send_reset(struct sk_buff *oldskb, int hook)
{
struct sk_buff *nskb;
const struct iphdr *oiph;
struct iphdr *niph;
const struct tcphdr *oth;
struct tcphdr _otcph, *tcph;
/* IP header checks: fragment. */
if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET))
return;
oth = skb_header_pointer(oldskb, ip_hdrlen(oldskb),
sizeof(_otcph), &_otcph);
if (oth == NULL)
return;
/* No RST for RST. */
if (oth->rst)
return;
if (skb_rtable(oldskb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
return;
/* Check checksum */
if (nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), IPPROTO_TCP))
return;
oiph = ip_hdr(oldskb);
nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) +
LL_MAX_HEADER, GFP_ATOMIC);
if (!nskb)
return;
skb_reserve(nskb, LL_MAX_HEADER);
skb_reset_network_header(nskb);
niph = (struct iphdr *)skb_put(nskb, sizeof(struct iphdr));
niph->version = 4;
niph->ihl = sizeof(struct iphdr) / 4;
niph->tos = 0;
niph->id = 0;
niph->frag_off = htons(IP_DF);
niph->protocol = IPPROTO_TCP;
niph->check = 0;
niph->saddr = oiph->daddr;
niph->daddr = oiph->saddr;
skb_reset_transport_header(nskb);
tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
memset(tcph, 0, sizeof(*tcph));
tcph->source = oth->dest;
tcph->dest = oth->source;
tcph->doff = sizeof(struct tcphdr) / 4;
if (oth->ack)
tcph->seq = oth->ack_seq;
else {
tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin +
oldskb->len - ip_hdrlen(oldskb) -
(oth->doff << 2));
tcph->ack = 1;
}
tcph->rst = 1;
tcph->check = ~tcp_v4_check(sizeof(struct tcphdr), niph->saddr,
niph->daddr, 0);
nskb->ip_summed = CHECKSUM_PARTIAL;
nskb->csum_start = (unsigned char *)tcph - nskb->head;
nskb->csum_offset = offsetof(struct tcphdr, check);
/* ip_route_me_harder expects skb->dst to be set */
skb_dst_set_noref(nskb, skb_dst(oldskb));
nskb->protocol = htons(ETH_P_IP);
if (ip_route_me_harder(nskb, RTN_UNSPEC))
goto free_nskb;
niph->ttl = ip4_dst_hoplimit(skb_dst(nskb));
/* "Never happens" */
if (nskb->len > dst_mtu(skb_dst(nskb)))
goto free_nskb;
nf_ct_attach(nskb, oldskb);
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
/* If we use ip_local_out for bridged traffic, the MAC source on
* the RST will be ours, instead of the destination's. This confuses
* some routers/firewalls, and they drop the packet. So we need to
* build the eth header using the original destination's MAC as the
* source, and send the RST packet directly.
*/
if (oldskb->nf_bridge) {
struct ethhdr *oeth = eth_hdr(oldskb);
nskb->dev = oldskb->nf_bridge->physindev;
niph->tot_len = htons(nskb->len);
ip_send_check(niph);
if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol),
oeth->h_source, oeth->h_dest, nskb->len) < 0)
goto free_nskb;
dev_queue_xmit(nskb);
} else
#endif
ip_local_out(nskb);
return;
free_nskb:
kfree_skb(nskb);
}
void nf_send_reset(struct sk_buff *oldskb, int hook);
#endif /* _IPV4_NF_REJECT_H */

6
net/ipv4/netfilter/Kconfig
View file

@ -61,8 +61,13 @@ config NFT_CHAIN_ROUTE_IPV4
fields such as the source, destination, type of service and
the packet mark.
config NF_REJECT_IPV4
tristate "IPv4 packet rejection"
default m if NETFILTER_ADVANCED=n
config NFT_REJECT_IPV4
depends on NF_TABLES_IPV4
select NF_REJECT_IPV4
default NFT_REJECT
tristate
@ -208,6 +213,7 @@ config IP_NF_FILTER
config IP_NF_TARGET_REJECT
tristate "REJECT target support"
depends on IP_NF_FILTER
select NF_REJECT_IPV4
default m if NETFILTER_ADVANCED=n
help
The REJECT target allows a filtering rule to specify that an ICMP

3
net/ipv4/netfilter/Makefile
View file

@ -23,6 +23,9 @@ obj-$(CONFIG_NF_DEFRAG_IPV4) += nf_defrag_ipv4.o
obj-$(CONFIG_NF_LOG_ARP) += nf_log_arp.o
obj-$(CONFIG_NF_LOG_IPV4) += nf_log_ipv4.o
# reject
obj-$(CONFIG_NF_REJECT_IPV4) += nf_reject_ipv4.o
# NAT helpers (nf_conntrack)
obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o
obj-$(CONFIG_NF_NAT_PPTP) += nf_nat_pptp.o

127
net/ipv4/netfilter/nf_reject_ipv4.c Normal file
View file

@ -0,0 +1,127 @@
/* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <net/ip.h>
#include <net/tcp.h>
#include <net/route.h>
#include <net/dst.h>
#include <linux/netfilter_ipv4.h>
/* Send RST reply */
void nf_send_reset(struct sk_buff *oldskb, int hook)
{
struct sk_buff *nskb;
const struct iphdr *oiph;
struct iphdr *niph;
const struct tcphdr *oth;
struct tcphdr _otcph, *tcph;
/* IP header checks: fragment. */
if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET))
return;
oth = skb_header_pointer(oldskb, ip_hdrlen(oldskb),
sizeof(_otcph), &_otcph);
if (oth == NULL)
return;
/* No RST for RST. */
if (oth->rst)
return;
if (skb_rtable(oldskb)->rt_flags & (RTCF_BROADCAST | RTCF_MULTICAST))
return;
/* Check checksum */
if (nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), IPPROTO_TCP))
return;
oiph = ip_hdr(oldskb);
nskb = alloc_skb(sizeof(struct iphdr) + sizeof(struct tcphdr) +
LL_MAX_HEADER, GFP_ATOMIC);
if (!nskb)
return;
skb_reserve(nskb, LL_MAX_HEADER);
skb_reset_network_header(nskb);
niph = (struct iphdr *)skb_put(nskb, sizeof(struct iphdr));
niph->version = 4;
niph->ihl = sizeof(struct iphdr) / 4;
niph->tos = 0;
niph->id = 0;
niph->frag_off = htons(IP_DF);
niph->protocol = IPPROTO_TCP;
niph->check = 0;
niph->saddr = oiph->daddr;
niph->daddr = oiph->saddr;
skb_reset_transport_header(nskb);
tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
memset(tcph, 0, sizeof(*tcph));
tcph->source = oth->dest;
tcph->dest = oth->source;
tcph->doff = sizeof(struct tcphdr) / 4;
if (oth->ack)
tcph->seq = oth->ack_seq;
else {
tcph->ack_seq = htonl(ntohl(oth->seq) + oth->syn + oth->fin +
oldskb->len - ip_hdrlen(oldskb) -
(oth->doff << 2));
tcph->ack = 1;
}
tcph->rst = 1;
tcph->check = ~tcp_v4_check(sizeof(struct tcphdr), niph->saddr,
niph->daddr, 0);
nskb->ip_summed = CHECKSUM_PARTIAL;
nskb->csum_start = (unsigned char *)tcph - nskb->head;
nskb->csum_offset = offsetof(struct tcphdr, check);
/* ip_route_me_harder expects skb->dst to be set */
skb_dst_set_noref(nskb, skb_dst(oldskb));
nskb->protocol = htons(ETH_P_IP);
if (ip_route_me_harder(nskb, RTN_UNSPEC))
goto free_nskb;
niph->ttl = ip4_dst_hoplimit(skb_dst(nskb));
/* "Never happens" */
if (nskb->len > dst_mtu(skb_dst(nskb)))
goto free_nskb;
nf_ct_attach(nskb, oldskb);
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
/* If we use ip_local_out for bridged traffic, the MAC source on
* the RST will be ours, instead of the destination's. This confuses
* some routers/firewalls, and they drop the packet. So we need to
* build the eth header using the original destination's MAC as the
* source, and send the RST packet directly.
*/
if (oldskb->nf_bridge) {
struct ethhdr *oeth = eth_hdr(oldskb);
nskb->dev = oldskb->nf_bridge->physindev;
niph->tot_len = htons(nskb->len);
ip_send_check(niph);
if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol),
oeth->h_source, oeth->h_dest, nskb->len) < 0)
goto free_nskb;
dev_queue_xmit(nskb);
} else
#endif
ip_local_out(nskb);
return;
free_nskb:
kfree_skb(nskb);
}
EXPORT_SYMBOL_GPL(nf_send_reset);

6
net/ipv6/netfilter/Kconfig
View file

@ -40,8 +40,13 @@ config NFT_CHAIN_ROUTE_IPV6
fields such as the source, destination, flowlabel, hop-limit and
the packet mark.
config NF_REJECT_IPV6
tristate "IPv6 packet rejection"
default m if NETFILTER_ADVANCED=n
config NFT_REJECT_IPV6
depends on NF_TABLES_IPV6
select NF_REJECT_IPV6
default NFT_REJECT
tristate
@ -208,6 +213,7 @@ config IP6_NF_FILTER
config IP6_NF_TARGET_REJECT
tristate "REJECT target support"
depends on IP6_NF_FILTER
select NF_REJECT_IPV6
default m if NETFILTER_ADVANCED=n
help
The REJECT target allows a filtering rule to specify that an ICMPv6

3
net/ipv6/netfilter/Makefile
View file

@ -27,6 +27,9 @@ obj-$(CONFIG_NF_DEFRAG_IPV6) += nf_defrag_ipv6.o
# logging
obj-$(CONFIG_NF_LOG_IPV6) += nf_log_ipv6.o
# reject
obj-$(CONFIG_NF_REJECT_IPV6) += nf_reject_ipv6.o
# nf_tables
obj-$(CONFIG_NF_TABLES_IPV6) += nf_tables_ipv6.o
obj-$(CONFIG_NFT_CHAIN_ROUTE_IPV6) += nft_chain_route_ipv6.o

163
net/ipv6/netfilter/nf_reject_ipv6.c Normal file
View file

@ -0,0 +1,163 @@
/* (C) 1999-2001 Paul `Rusty' Russell
* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <net/ipv6.h>
#include <net/ip6_route.h>
#include <net/ip6_fib.h>
#include <net/ip6_checksum.h>
#include <linux/netfilter_ipv6.h>
void nf_send_reset6(struct net *net, struct sk_buff *oldskb, int hook)
{
struct sk_buff *nskb;
struct tcphdr otcph, *tcph;
unsigned int otcplen, hh_len;
int tcphoff, needs_ack;
const struct ipv6hdr *oip6h = ipv6_hdr(oldskb);
struct ipv6hdr *ip6h;
#define DEFAULT_TOS_VALUE 0x0U
const __u8 tclass = DEFAULT_TOS_VALUE;
struct dst_entry *dst = NULL;
u8 proto;
__be16 frag_off;
struct flowi6 fl6;
if ((!(ipv6_addr_type(&oip6h->saddr) & IPV6_ADDR_UNICAST)) ||
(!(ipv6_addr_type(&oip6h->daddr) & IPV6_ADDR_UNICAST))) {
pr_debug("addr is not unicast.\n");
return;
}
proto = oip6h->nexthdr;
tcphoff = ipv6_skip_exthdr(oldskb, ((u8*)(oip6h+1) - oldskb->data), &proto, &frag_off);
if ((tcphoff < 0) || (tcphoff > oldskb->len)) {
pr_debug("Cannot get TCP header.\n");
return;
}
otcplen = oldskb->len - tcphoff;
/* IP header checks: fragment, too short. */
if (proto != IPPROTO_TCP || otcplen < sizeof(struct tcphdr)) {
pr_debug("proto(%d) != IPPROTO_TCP, "
"or too short. otcplen = %d\n",
proto, otcplen);
return;
}
if (skb_copy_bits(oldskb, tcphoff, &otcph, sizeof(struct tcphdr)))
BUG();
/* No RST for RST. */
if (otcph.rst) {
pr_debug("RST is set\n");
return;
}
/* Check checksum. */
if (nf_ip6_checksum(oldskb, hook, tcphoff, IPPROTO_TCP)) {
pr_debug("TCP checksum is invalid\n");
return;
}
memset(&fl6, 0, sizeof(fl6));
fl6.flowi6_proto = IPPROTO_TCP;
fl6.saddr = oip6h->daddr;
fl6.daddr = oip6h->saddr;
fl6.fl6_sport = otcph.dest;
fl6.fl6_dport = otcph.source;
security_skb_classify_flow(oldskb, flowi6_to_flowi(&fl6));
dst = ip6_route_output(net, NULL, &fl6);
if (dst == NULL || dst->error) {
dst_release(dst);
return;
}
dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0);
if (IS_ERR(dst))
return;
hh_len = (dst->dev->hard_header_len + 15)&~15;
nskb = alloc_skb(hh_len + 15 + dst->header_len + sizeof(struct ipv6hdr)
+ sizeof(struct tcphdr) + dst->trailer_len,
GFP_ATOMIC);
if (!nskb) {
net_dbg_ratelimited("cannot alloc skb\n");
dst_release(dst);
return;
}
skb_dst_set(nskb, dst);
skb_reserve(nskb, hh_len + dst->header_len);
skb_put(nskb, sizeof(struct ipv6hdr));
skb_reset_network_header(nskb);
ip6h = ipv6_hdr(nskb);
ip6_flow_hdr(ip6h, tclass, 0);
ip6h->hop_limit = ip6_dst_hoplimit(dst);
ip6h->nexthdr = IPPROTO_TCP;
ip6h->saddr = oip6h->daddr;
ip6h->daddr = oip6h->saddr;
skb_reset_transport_header(nskb);
tcph = (struct tcphdr *)skb_put(nskb, sizeof(struct tcphdr));
/* Truncate to length (no data) */
tcph->doff = sizeof(struct tcphdr)/4;
tcph->source = otcph.dest;
tcph->dest = otcph.source;
if (otcph.ack) {
needs_ack = 0;
tcph->seq = otcph.ack_seq;
tcph->ack_seq = 0;
} else {
needs_ack = 1;
tcph->ack_seq = htonl(ntohl(otcph.seq) + otcph.syn + otcph.fin
+ otcplen - (otcph.doff<<2));
tcph->seq = 0;
}
/* Reset flags */
((u_int8_t *)tcph)[13] = 0;
tcph->rst = 1;
tcph->ack = needs_ack;
tcph->window = 0;
tcph->urg_ptr = 0;
tcph->check = 0;
/* Adjust TCP checksum */
tcph->check = csum_ipv6_magic(&ipv6_hdr(nskb)->saddr,
&ipv6_hdr(nskb)->daddr,
sizeof(struct tcphdr), IPPROTO_TCP,
csum_partial(tcph,
sizeof(struct tcphdr), 0));
nf_ct_attach(nskb, oldskb);
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
/* If we use ip6_local_out for bridged traffic, the MAC source on
* the RST will be ours, instead of the destination's. This confuses
* some routers/firewalls, and they drop the packet. So we need to
* build the eth header using the original destination's MAC as the
* source, and send the RST packet directly.
*/
if (oldskb->nf_bridge) {
struct ethhdr *oeth = eth_hdr(oldskb);
nskb->dev = oldskb->nf_bridge->physindev;
nskb->protocol = htons(ETH_P_IPV6);
ip6h->payload_len = htons(sizeof(struct tcphdr));
if (dev_hard_header(nskb, nskb->dev, ntohs(nskb->protocol),
oeth->h_source, oeth->h_dest, nskb->len) < 0)
return;
dev_queue_xmit(nskb);
} else
#endif
ip6_local_out(nskb);
}
EXPORT_SYMBOL_GPL(nf_send_reset6);