net: add a sysctl to reflect the fwmark on replies
Kernel-originated IP packets that have no user socket associated
with them (e.g., ICMP errors and echo replies, TCP RSTs, etc.)
are emitted with a mark of zero. Add a sysctl to make them have
the same mark as the packet they are replying to.
This allows an administrator that wishes to do so to use
mark-based routing, firewalling, etc. for these replies by
marking the original packets inbound.
Tested using user-mode linux:
- ICMP/ICMPv6 echo replies and errors.
- TCP RST packets (IPv4 and IPv6).
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 5b40ad2..ba810d0 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -113,6 +113,9 @@
#define IP6_MF 0x0001
#define IP6_OFFSET 0xFFF8
+#define IP6_REPLY_MARK(net, mark) \
+ ((net)->ipv6.sysctl.fwmark_reflect ? (mark) : 0)
+
#include <net/sock.h>
/* sysctls */