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authorHannes Frederic Sowa <hannes@stressinduktion.org>2013-03-15 11:32:30 +0000
committerDavid S. Miller <davem@davemloft.net>2013-03-19 10:28:36 -0400
commit5a3da1fe9561828d0ca7eca664b16ec2b9bf0055 (patch)
treeb7bbaabf1271af7d912e9bdbb7f5810d2d0a5d3e /net/ipv4/inet_fragment.c
parent271648b4c610eed540daaf9ff366209825757565 (diff)
inet: limit length of fragment queue hash table bucket lists
This patch introduces a constant limit of the fragment queue hash table bucket list lengths. Currently the limit 128 is choosen somewhat arbitrary and just ensures that we can fill up the fragment cache with empty packets up to the default ip_frag_high_thresh limits. It should just protect from list iteration eating considerable amounts of cpu. If we reach the maximum length in one hash bucket a warning is printed. This is implemented on the caller side of inet_frag_find to distinguish between the different users of inet_fragment.c. I dropped the out of memory warning in the ipv4 fragment lookup path, because we already get a warning by the slab allocator. Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Jesper Dangaard Brouer <jbrouer@redhat.com> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/inet_fragment.c')
-rw-r--r--net/ipv4/inet_fragment.c20
1 files changed, 19 insertions, 1 deletions
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index 245ae078a07f..f4fd23de9b13 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -21,6 +21,7 @@
#include <linux/rtnetlink.h>
#include <linux/slab.h>
+#include <net/sock.h>
#include <net/inet_frag.h>
static void inet_frag_secret_rebuild(unsigned long dummy)
@@ -277,6 +278,7 @@ struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
__releases(&f->lock)
{
struct inet_frag_queue *q;
+ int depth = 0;
hlist_for_each_entry(q, &f->hash[hash], list) {
if (q->net == nf && f->match(q, key)) {
@@ -284,9 +286,25 @@ struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
read_unlock(&f->lock);
return q;
}
+ depth++;
}
read_unlock(&f->lock);
- return inet_frag_create(nf, f, key);
+ if (depth <= INETFRAGS_MAXDEPTH)
+ return inet_frag_create(nf, f, key);
+ else
+ return ERR_PTR(-ENOBUFS);
}
EXPORT_SYMBOL(inet_frag_find);
+
+void inet_frag_maybe_warn_overflow(struct inet_frag_queue *q,
+ const char *prefix)
+{
+ static const char msg[] = "inet_frag_find: Fragment hash bucket"
+ " list length grew over limit " __stringify(INETFRAGS_MAXDEPTH)
+ ". Dropping fragment.\n";
+
+ if (PTR_ERR(q) == -ENOBUFS)
+ LIMIT_NETDEBUG(KERN_WARNING "%s%s", prefix, msg);
+}
+EXPORT_SYMBOL(inet_frag_maybe_warn_overflow);