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authorHerbert Xu <herbert@gondor.apana.org.au>2005-12-13 23:14:27 -0800
committerDavid S. Miller <davem@sunset.davemloft.net>2006-01-03 13:10:31 -0800
commit89cee8b1cbb9dac40c92ef1968aea2b45f82fd18 (patch)
tree01049841b15a9c2f3f136710382c7e4c11c1b1e5 /Documentation/networking
parentd5228a4f49db32d22a39c653281b527ef371129c (diff)
[IPV4]: Safer reassembly
Another spin of Herbert Xu's "safer ip reassembly" patch for 2.6.16. (The original patch is here: http://marc.theaimsgroup.com/?l=linux-netdev&m=112281936522415&w=2 and my only contribution is to have tested it.) This patch (optionally) does additional checks before accepting IP fragments, which can greatly reduce the possibility of reassembling fragments which originated from different IP datagrams. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Arthur Kepner <akepner@sgi.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/ip-sysctl.txt23
1 files changed, 23 insertions, 0 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index ebc09a159f6..2b7cf19a06a 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -46,6 +46,29 @@ ipfrag_secret_interval - INTEGER
for the hash secret) for IP fragments.
Default: 600
+ipfrag_max_dist - INTEGER
+ ipfrag_max_dist is a non-negative integer value which defines the
+ maximum "disorder" which is allowed among fragments which share a
+ common IP source address. Note that reordering of packets is
+ not unusual, but if a large number of fragments arrive from a source
+ IP address while a particular fragment queue remains incomplete, it
+ probably indicates that one or more fragments belonging to that queue
+ have been lost. When ipfrag_max_dist is positive, an additional check
+ is done on fragments before they are added to a reassembly queue - if
+ ipfrag_max_dist (or more) fragments have arrived from a particular IP
+ address between additions to any IP fragment queue using that source
+ address, it's presumed that one or more fragments in the queue are
+ lost. The existing fragment queue will be dropped, and a new one
+ started. An ipfrag_max_dist value of zero disables this check.
+
+ Using a very small value, e.g. 1 or 2, for ipfrag_max_dist can
+ result in unnecessarily dropping fragment queues when normal
+ reordering of packets occurs, which could lead to poor application
+ performance. Using a very large value, e.g. 50000, increases the
+ likelihood of incorrectly reassembling IP fragments that originate
+ from different IP datagrams, which could result in data corruption.
+ Default: 64
+
INET peer storage:
inet_peer_threshold - INTEGER