From 723884339f90a9c420783135168cc1045750eb5d Mon Sep 17 00:00:00 2001 From: Bhaskar Dutta Date: Thu, 3 Sep 2009 17:25:47 +0530 Subject: sctp: Sysctl configuration for IPv4 Address Scoping This patch introduces a new sysctl option to make IPv4 Address Scoping configurable . In networking environments where DNAT rules in iptables prerouting chains convert destination IP's to link-local/private IP addresses, SCTP connections fail to establish as the INIT chunk is dropped by the kernel due to address scope match failure. For example to support overlapping IP addresses (same IP address with different vlan id) a Layer-5 application listens on link local IP's, and there is a DNAT rule that maps the destination IP to a link local IP. Such applications never get the SCTP INIT if the address-scoping draft is strictly followed. This sysctl configuration allows SCTP to function in such unconventional networking environments. Sysctl options: 0 - Disable IPv4 address scoping draft altogether 1 - Enable IPv4 address scoping (default, current behavior) 2 - Enable address scoping but allow IPv4 private addresses in init/init-ack 3 - Enable address scoping but allow IPv4 link local address in init/init-ack Signed-off-by: Bhaskar Dutta Signed-off-by: Vlad Yasevich --- net/sctp/protocol.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'net/sctp/protocol.c') diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c index a76da657244..60093be8385 100644 --- a/net/sctp/protocol.c +++ b/net/sctp/protocol.c @@ -431,16 +431,14 @@ static int sctp_v4_available(union sctp_addr *addr, struct sctp_sock *sp) * of requested destination address, sender and receiver * SHOULD include all of its addresses with level greater * than or equal to L. + * + * IPv4 scoping can be controlled through sysctl option + * net.sctp.addr_scope_policy */ static sctp_scope_t sctp_v4_scope(union sctp_addr *addr) { sctp_scope_t retval; - /* Should IPv4 scoping be a sysctl configurable option - * so users can turn it off (default on) for certain - * unconventional networking environments? - */ - /* Check for unusable SCTP addresses. */ if (IS_IPV4_UNUSABLE_ADDRESS(addr->v4.sin_addr.s_addr)) { retval = SCTP_SCOPE_UNUSABLE; @@ -1259,6 +1257,9 @@ SCTP_STATIC __init int sctp_init(void) /* Disable AUTH by default. */ sctp_auth_enable = 0; + /* Set SCOPE policy to enabled */ + sctp_scope_policy = SCTP_SCOPE_POLICY_ENABLE; + sctp_sysctl_register(); INIT_LIST_HEAD(&sctp_address_families); -- cgit v1.2.3-18-g5258