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Date: Thu, 2 Jul 2015 10:56:01 +0200
From: Matteo Croce <matteo@...nwrt.org>
To: nicolas.dichtel@...nd.com
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] add stealth mode
Add option to disable any reply not related to a listening socket,
like RST/ACK for TCP and ICMP Port-Unreachable for UDP.
Also disables ICMP replies to echo request and timestamp.
The stealth mode can be enabled selectively for a single interface.
Signed-off-by: Matteo Croce <matteo@...nwrt.org>
---
check the patch with checkpatch.pl and add documentation in ip-sysctl.txt
Documentation/networking/ip-sysctl.txt | 12 ++++++++++++
include/linux/inetdevice.h | 1 +
include/linux/ipv6.h | 1 +
include/uapi/linux/ip.h | 1 +
net/ipv4/devinet.c | 1 +
net/ipv4/icmp.c | 6 ++++++
net/ipv4/tcp_ipv4.c | 3 ++-
net/ipv4/udp.c | 4 +++-
net/ipv6/addrconf.c | 7 +++++++
net/ipv6/icmp.c | 3 ++-
net/ipv6/tcp_ipv6.c | 2 +-
net/ipv6/udp.c | 3 ++-
12 files changed, 39 insertions(+), 5 deletions(-)
diff --git a/Documentation/networking/ip-sysctl.txt
b/Documentation/networking/ip-sysctl.txt
index 5fae770..9eed021 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -1181,6 +1181,12 @@ tag - INTEGER
Allows you to write a number, which can be used as required.
Default value is 0.
+stealth - BOOLEAN
+ Disable any reply not related to a listening socket,
+ like RST/ACK for TCP and ICMP Port-Unreachable for UDP.
+ Also disables ICMP replies to echo requests and timestamp.
+ Default value is 0.
+
Alexey Kuznetsov.
kuznet@....inr.ac.ru
@@ -1584,6 +1590,12 @@ stable_secret - IPv6 address
By default the stable secret is unset.
+stealth - BOOLEAN
+ Disable any reply not related to a listening socket,
+ like RST/ACK for TCP and ICMP Port-Unreachable for UDP.
+ Also disables ICMPv6 replies to echo requests.
+ Default value is 0.
+
icmp/*:
ratelimit - INTEGER
Limit the maximal rates for sending ICMPv6 packets.
diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
index a4328ce..a64c01e 100644
--- a/include/linux/inetdevice.h
+++ b/include/linux/inetdevice.h
@@ -128,6 +128,7 @@ static inline void ipv4_devconf_setall(struct
in_device *in_dev)
#define IN_DEV_ARP_ANNOUNCE(in_dev) IN_DEV_MAXCONF((in_dev), ARP_ANNOUNCE)
#define IN_DEV_ARP_IGNORE(in_dev) IN_DEV_MAXCONF((in_dev), ARP_IGNORE)
#define IN_DEV_ARP_NOTIFY(in_dev) IN_DEV_MAXCONF((in_dev), ARP_NOTIFY)
+#define IN_DEV_STEALTH(in_dev) IN_DEV_MAXCONF((in_dev), STEALTH)
struct in_ifaddr {
struct hlist_node hash;
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 82806c6..49494ec 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -53,6 +53,7 @@ struct ipv6_devconf {
__s32 ndisc_notify;
__s32 suppress_frag_ndisc;
__s32 accept_ra_mtu;
+ __s32 stealth;
struct ipv6_stable_secret {
bool initialized;
struct in6_addr secret;
diff --git a/include/uapi/linux/ip.h b/include/uapi/linux/ip.h
index 08f894d..4acbf99 100644
--- a/include/uapi/linux/ip.h
+++ b/include/uapi/linux/ip.h
@@ -165,6 +165,7 @@ enum
IPV4_DEVCONF_IGMPV2_UNSOLICITED_REPORT_INTERVAL,
IPV4_DEVCONF_IGMPV3_UNSOLICITED_REPORT_INTERVAL,
IPV4_DEVCONF_IGNORE_ROUTES_WITH_LINKDOWN,
+ IPV4_DEVCONF_STEALTH,
__IPV4_DEVCONF_MAX
};
diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
index 7498716..6b9930a 100644
--- a/net/ipv4/devinet.c
+++ b/net/ipv4/devinet.c
@@ -2178,6 +2178,7 @@ static struct devinet_sysctl_table {
"promote_secondaries"),
DEVINET_SYSCTL_FLUSHING_ENTRY(ROUTE_LOCALNET,
"route_localnet"),
+ DEVINET_SYSCTL_RW_ENTRY(STEALTH, "stealth"),
},
};
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index f5203fb..e8e71fb 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -882,6 +882,9 @@ static bool icmp_echo(struct sk_buff *skb)
{
struct net *net;
+ if (IN_DEV_STEALTH(skb->dev->ip_ptr))
+ return true;
+
net = dev_net(skb_dst(skb)->dev);
if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
struct icmp_bxm icmp_param;
@@ -915,6 +918,9 @@ static bool icmp_timestamp(struct sk_buff *skb)
if (skb->len < 4)
goto out_err;
+ if (IN_DEV_STEALTH(skb->dev->ip_ptr))
+ return true;
+
/*
* Fill in the current time as ms since midnight UT:
*/
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index d7d4c2b..6f3e6e9 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -77,6 +77,7 @@
#include <net/busy_poll.h>
#include <linux/inet.h>
+#include <linux/inetdevice.h>
#include <linux/ipv6.h>
#include <linux/stddef.h>
#include <linux/proc_fs.h>
@@ -1652,7 +1653,7 @@ csum_error:
TCP_INC_STATS_BH(net, TCP_MIB_CSUMERRORS);
bad_packet:
TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
- } else {
+ } else if (!IN_DEV_STEALTH(skb->dev->ip_ptr)) {
tcp_v4_send_reset(NULL, skb);
}
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 83aa604..780069d 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -96,6 +96,7 @@
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/inet.h>
+#include <linux/inetdevice.h>
#include <linux/netdevice.h>
#include <linux/slab.h>
#include <net/tcp_states.h>
@@ -1823,7 +1824,8 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct
udp_table *udptable,
goto csum_error;
UDP_INC_STATS_BH(net, UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE);
- icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
+ if (!IN_DEV_STEALTH(skb->dev->ip_ptr))
+ icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
/*
* Hmm. We got an UDP packet to a port to which we
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 21c2c81..b9e44e2 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -5585,6 +5585,13 @@ static struct addrconf_sysctl_table
.proc_handler = addrconf_sysctl_stable_secret,
},
{
+ .procname = "stealth",
+ .data = &ipv6_devconf.stealth,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+ {
/* sentinel */
}
},
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 713d743..47797a6 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -723,7 +723,8 @@ static int icmpv6_rcv(struct sk_buff *skb)
switch (type) {
case ICMPV6_ECHO_REQUEST:
- icmpv6_echo_reply(skb);
+ if (!idev->cnf.stealth)
+ icmpv6_echo_reply(skb);
break;
case ICMPV6_ECHO_REPLY:
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 6748c42..cb41856 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1445,7 +1445,7 @@ csum_error:
TCP_INC_STATS_BH(net, TCP_MIB_CSUMERRORS);
bad_packet:
TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
- } else {
+ } else if (!__in6_dev_get(skb->dev)->cnf.stealth) {
tcp_v6_send_reset(NULL, skb);
}
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index e51fc3e..459238bb 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -934,7 +934,8 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct
udp_table *udptable,
goto csum_error;
UDP6_INC_STATS_BH(net, UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE);
- icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
+ if (!__in6_dev_get(skb->dev)->cnf.stealth)
+ icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
kfree_skb(skb);
return 0;
--
2.1.4
--
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