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stealth

teknoraver
Jul 1st, 2015
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  1. From 2a96213b42233a43901f9a38abd6d7b5da9b0a93 Mon Sep 17 00:00:00 2001
  2. From: Matteo Croce <matteo@openwrt.org>
  3. Date: Thu, 2 Jul 2015 00:30:22 +0200
  4. Subject: [PATCH] add stealth mode
  5.  
  6. Add option to disable any reply not related to a listening socket,
  7. like RST/ACK for TCP and ICMP Dest-Unreach for UDP.
  8. Also disables ICMP replies to echo request and timestamp.
  9. The stealth mode can be enabled selectively for a single interface.
  10. ---
  11. include/linux/inetdevice.h | 1 +
  12.  include/linux/ipv6.h       | 1 +
  13.  include/uapi/linux/ip.h    | 1 +
  14.  net/ipv4/devinet.c         | 1 +
  15.  net/ipv4/icmp.c            | 6 ++++++
  16.  net/ipv4/tcp_ipv4.c        | 3 ++-
  17.  net/ipv4/udp.c             | 4 +++-
  18.  net/ipv6/addrconf.c        | 7 +++++++
  19.  net/ipv6/icmp.c            | 3 ++-
  20.  net/ipv6/tcp_ipv6.c        | 2 +-
  21.  net/ipv6/udp.c             | 3 ++-
  22.  11 files changed, 27 insertions(+), 5 deletions(-)
  23.  
  24. diff --git a/include/linux/inetdevice.h b/include/linux/inetdevice.h
  25. index a4328ce..a64c01e 100644
  26. --- a/include/linux/inetdevice.h
  27. +++ b/include/linux/inetdevice.h
  28. @@ -128,6 +128,7 @@ static inline void ipv4_devconf_setall(struct in_device *in_dev)
  29.  #define IN_DEV_ARP_ANNOUNCE(in_dev)    IN_DEV_MAXCONF((in_dev), ARP_ANNOUNCE)
  30.  #define IN_DEV_ARP_IGNORE(in_dev)  IN_DEV_MAXCONF((in_dev), ARP_IGNORE)
  31.  #define IN_DEV_ARP_NOTIFY(in_dev)  IN_DEV_MAXCONF((in_dev), ARP_NOTIFY)
  32. +#define IN_DEV_STEALTH(in_dev)     IN_DEV_MAXCONF((in_dev), STEALTH)
  33.  
  34.  struct in_ifaddr {
  35.     struct hlist_node   hash;
  36. diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
  37. index 82806c6..49494ec 100644
  38. --- a/include/linux/ipv6.h
  39. +++ b/include/linux/ipv6.h
  40. @@ -53,6 +53,7 @@ struct ipv6_devconf {
  41.     __s32           ndisc_notify;
  42.     __s32       suppress_frag_ndisc;
  43.     __s32       accept_ra_mtu;
  44. +   __s32       stealth;
  45.     struct ipv6_stable_secret {
  46.         bool initialized;
  47.         struct in6_addr secret;
  48. diff --git a/include/uapi/linux/ip.h b/include/uapi/linux/ip.h
  49. index 08f894d..4acbf99 100644
  50. --- a/include/uapi/linux/ip.h
  51. +++ b/include/uapi/linux/ip.h
  52. @@ -165,6 +165,7 @@ enum
  53.     IPV4_DEVCONF_IGMPV2_UNSOLICITED_REPORT_INTERVAL,
  54.     IPV4_DEVCONF_IGMPV3_UNSOLICITED_REPORT_INTERVAL,
  55.     IPV4_DEVCONF_IGNORE_ROUTES_WITH_LINKDOWN,
  56. +   IPV4_DEVCONF_STEALTH,
  57.     __IPV4_DEVCONF_MAX
  58.  };
  59.  
  60. diff --git a/net/ipv4/devinet.c b/net/ipv4/devinet.c
  61. index 7498716..6b9930a 100644
  62. --- a/net/ipv4/devinet.c
  63. +++ b/net/ipv4/devinet.c
  64. @@ -2178,6 +2178,7 @@ static struct devinet_sysctl_table {
  65.                           "promote_secondaries"),
  66.         DEVINET_SYSCTL_FLUSHING_ENTRY(ROUTE_LOCALNET,
  67.                           "route_localnet"),
  68. +       DEVINET_SYSCTL_RW_ENTRY(STEALTH, "stealth"),
  69.     },
  70.  };
  71.  
  72. diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
  73. index f5203fb..2f1b31f 100644
  74. --- a/net/ipv4/icmp.c
  75. +++ b/net/ipv4/icmp.c
  76. @@ -882,6 +882,9 @@ static bool icmp_echo(struct sk_buff *skb)
  77.  {
  78.     struct net *net;
  79.  
  80. +   if(IN_DEV_STEALTH(skb->dev->ip_ptr))
  81. +       return true;
  82. +
  83.     net = dev_net(skb_dst(skb)->dev);
  84.     if (!net->ipv4.sysctl_icmp_echo_ignore_all) {
  85.         struct icmp_bxm icmp_param;
  86. @@ -915,6 +918,9 @@ static bool icmp_timestamp(struct sk_buff *skb)
  87.     if (skb->len < 4)
  88.         goto out_err;
  89.  
  90. +   if(IN_DEV_STEALTH(skb->dev->ip_ptr))
  91. +       return true;
  92. +
  93.     /*
  94.      *  Fill in the current time as ms since midnight UT:
  95.      */
  96. diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
  97. index d7d4c2b..c887d6e 100644
  98. --- a/net/ipv4/tcp_ipv4.c
  99. +++ b/net/ipv4/tcp_ipv4.c
  100. @@ -77,6 +77,7 @@
  101.  #include <net/busy_poll.h>
  102.  
  103.  #include <linux/inet.h>
  104. +#include <linux/inetdevice.h>
  105.  #include <linux/ipv6.h>
  106.  #include <linux/stddef.h>
  107.  #include <linux/proc_fs.h>
  108. @@ -1652,7 +1653,7 @@ csum_error:
  109.         TCP_INC_STATS_BH(net, TCP_MIB_CSUMERRORS);
  110.  bad_packet:
  111.         TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
  112. -   } else {
  113. +   } else if(!IN_DEV_STEALTH(skb->dev->ip_ptr)) {
  114.         tcp_v4_send_reset(NULL, skb);
  115.     }
  116.  
  117. diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
  118. index 83aa604..b3b0dee 100644
  119. --- a/net/ipv4/udp.c
  120. +++ b/net/ipv4/udp.c
  121. @@ -96,6 +96,7 @@
  122.  #include <linux/timer.h>
  123.  #include <linux/mm.h>
  124.  #include <linux/inet.h>
  125. +#include <linux/inetdevice.h>
  126.  #include <linux/netdevice.h>
  127.  #include <linux/slab.h>
  128.  #include <net/tcp_states.h>
  129. @@ -1823,7 +1824,8 @@ int __udp4_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
  130.         goto csum_error;
  131.  
  132.     UDP_INC_STATS_BH(net, UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE);
  133. -   icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
  134. +   if(!IN_DEV_STEALTH(skb->dev->ip_ptr))
  135. +       icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0);
  136.  
  137.     /*
  138.      * Hmm.  We got an UDP packet to a port to which we
  139. diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
  140. index 21c2c81..b9e44e2 100644
  141. --- a/net/ipv6/addrconf.c
  142. +++ b/net/ipv6/addrconf.c
  143. @@ -5585,6 +5585,13 @@ static struct addrconf_sysctl_table
  144.             .proc_handler   = addrconf_sysctl_stable_secret,
  145.         },
  146.         {
  147. +           .procname   = "stealth",
  148. +           .data       = &ipv6_devconf.stealth,
  149. +           .maxlen     = sizeof(int),
  150. +           .mode       = 0644,
  151. +           .proc_handler   = proc_dointvec,
  152. +       },
  153. +       {
  154.             /* sentinel */
  155.         }
  156.     },
  157. diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
  158. index 713d743..94b08ac 100644
  159. --- a/net/ipv6/icmp.c
  160. +++ b/net/ipv6/icmp.c
  161. @@ -723,7 +723,8 @@ static int icmpv6_rcv(struct sk_buff *skb)
  162.  
  163.     switch (type) {
  164.     case ICMPV6_ECHO_REQUEST:
  165. -       icmpv6_echo_reply(skb);
  166. +       if(!idev->cnf.stealth)
  167. +           icmpv6_echo_reply(skb);
  168.         break;
  169.  
  170.     case ICMPV6_ECHO_REPLY:
  171. diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
  172. index 6748c42..cae96d7 100644
  173. --- a/net/ipv6/tcp_ipv6.c
  174. +++ b/net/ipv6/tcp_ipv6.c
  175. @@ -1445,7 +1445,7 @@ csum_error:
  176.         TCP_INC_STATS_BH(net, TCP_MIB_CSUMERRORS);
  177.  bad_packet:
  178.         TCP_INC_STATS_BH(net, TCP_MIB_INERRS);
  179. -   } else {
  180. +   } else if(!__in6_dev_get(skb->dev)->cnf.stealth) {
  181.         tcp_v6_send_reset(NULL, skb);
  182.     }
  183.  
  184. diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
  185. index e51fc3e..c0cee63 100644
  186. --- a/net/ipv6/udp.c
  187. +++ b/net/ipv6/udp.c
  188. @@ -934,7 +934,8 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
  189.         goto csum_error;
  190.  
  191.     UDP6_INC_STATS_BH(net, UDP_MIB_NOPORTS, proto == IPPROTO_UDPLITE);
  192. -   icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
  193. +   if(!__in6_dev_get(skb->dev)->cnf.stealth)
  194. +       icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);
  195.  
  196.     kfree_skb(skb);
  197.     return 0;
  198. --
  199. 2.1.4
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