ipv6: Add rate limit mask for ICMPv6 messages

To make ICMPv6 closer to ICMPv4, add ratemask parameter. Since the ICMP
message types use larger numeric values, a simple bitmask doesn't fit.
I use large bitmap. The input and output are the in form of list of
ranges. Set the default to rate limit all error messages but Packet Too
Big. For Packet Too Big, use ratemask instead of hard-coded.

There are functions where icmpv6_xrlim_allow() and icmpv6_global_allow()
aren't called. This patch only adds them to icmpv6_echo_reply().

Rate limiting error messages is mandated by RFC 4443 but RFC 4890 says
that it is also acceptable to rate limit informational messages. Thus,
I removed the current hard-coded behavior of icmpv6_mask_allow() that
doesn't rate limit informational messages.

v2: Add dummy function proc_do_large_bitmap() if CONFIG_PROC_SYSCTL
    isn't defined, expand the description in ip-sysctl.txt and remove
    unnecessary conditional before kfree().
v3: Inline the bitmap instead of dynamically allocated. Still is a
    pointer to it is needed because of the way proc_do_large_bitmap work.

Signed-off-by: Stephen Suryaputra <ssuryaextr@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 1 deletions

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 5eedc6941ce5..8a5e59ba223f 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -1913,11 +1913,26 @@ enhanced_dad - BOOLEAN
 
 icmp/*:
 ratelimit - INTEGER
-	Limit the maximal rates for sending ICMPv6 packets.
+	Limit the maximal rates for sending ICMPv6 messages.
 	0 to disable any limiting,
 	otherwise the minimal space between responses in milliseconds.
 	Default: 1000
 
+ratemask - list of comma separated ranges
+	For ICMPv6 message types matching the ranges in the ratemask, limit
+	the sending of the message according to ratelimit parameter.
+
+	The format used for both input and output is a comma separated
+	list of ranges (e.g. "0-127,129" for ICMPv6 message type 0 to 127 and
+	129). Writing to the file will clear all previous ranges of ICMPv6
+	message types and update the current list with the input.
+
+	Refer to: https://www.iana.org/assignments/icmpv6-parameters/icmpv6-parameters.xhtml
+	for numerical values of ICMPv6 message types, e.g. echo request is 128
+	and echo reply is 129.
+
+	Default: 0-1,3-127 (rate limit ICMPv6 errors except Packet Too Big)
+
 echo_ignore_all - BOOLEAN
 	If set non-zero, then the kernel will ignore all ICMP ECHO
 	requests sent to it over the IPv6 protocol.