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Date: Wed, 2 Nov 2022 19:46:59 +0100
From: Pablo Neira Ayuso <pablo@...filter.org>
To: netfilter-devel@...r.kernel.org
Cc: davem@...emloft.net, netdev@...r.kernel.org, kuba@...nel.org,
pabeni@...hat.com, edumazet@...gle.com
Subject: [PATCH net 7/7] netfilter: ipset: enforce documented limit to prevent allocating huge memory
From: Jozsef Kadlecsik <kadlec@...filter.org>
Daniel Xu reported that the hash:net,iface type of the ipset subsystem does
not limit adding the same network with different interfaces to a set, which
can lead to huge memory usage or allocation failure.
The quick reproducer is
$ ipset create ACL.IN.ALL_PERMIT hash:net,iface hashsize 1048576 timeout 0
$ for i in $(seq 0 100); do /sbin/ipset add ACL.IN.ALL_PERMIT 0.0.0.0/0,kaf_$i timeout 0 -exist; done
The backtrace when vmalloc fails:
[Tue Oct 25 00:13:08 2022] ipset: vmalloc error: size 1073741848, exceeds total pages
<...>
[Tue Oct 25 00:13:08 2022] Call Trace:
[Tue Oct 25 00:13:08 2022] <TASK>
[Tue Oct 25 00:13:08 2022] dump_stack_lvl+0x48/0x60
[Tue Oct 25 00:13:08 2022] warn_alloc+0x155/0x180
[Tue Oct 25 00:13:08 2022] __vmalloc_node_range+0x72a/0x760
[Tue Oct 25 00:13:08 2022] ? hash_netiface4_add+0x7c0/0xb20
[Tue Oct 25 00:13:08 2022] ? __kmalloc_large_node+0x4a/0x90
[Tue Oct 25 00:13:08 2022] kvmalloc_node+0xa6/0xd0
[Tue Oct 25 00:13:08 2022] ? hash_netiface4_resize+0x99/0x710
<...>
The fix is to enforce the limit documented in the ipset(8) manpage:
> The internal restriction of the hash:net,iface set type is that the same
> network prefix cannot be stored with more than 64 different interfaces
> in a single set.
Fixes: ccf0a4b7fc68 ("netfilter: ipset: Add bucketsize parameter to all hash types")
Reported-by: Daniel Xu <dxu@...uu.xyz>
Signed-off-by: Jozsef Kadlecsik <kadlec@...filter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
---
net/netfilter/ipset/ip_set_hash_gen.h | 30 ++++++---------------------
1 file changed, 6 insertions(+), 24 deletions(-)
diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h
index 6e391308431d..3adc291d9ce1 100644
--- a/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/net/netfilter/ipset/ip_set_hash_gen.h
@@ -42,31 +42,8 @@
#define AHASH_MAX_SIZE (6 * AHASH_INIT_SIZE)
/* Max muber of elements in the array block when tuned */
#define AHASH_MAX_TUNED 64
-
#define AHASH_MAX(h) ((h)->bucketsize)
-/* Max number of elements can be tuned */
-#ifdef IP_SET_HASH_WITH_MULTI
-static u8
-tune_bucketsize(u8 curr, u32 multi)
-{
- u32 n;
-
- if (multi < curr)
- return curr;
-
- n = curr + AHASH_INIT_SIZE;
- /* Currently, at listing one hash bucket must fit into a message.
- * Therefore we have a hard limit here.
- */
- return n > curr && n <= AHASH_MAX_TUNED ? n : curr;
-}
-#define TUNE_BUCKETSIZE(h, multi) \
- ((h)->bucketsize = tune_bucketsize((h)->bucketsize, multi))
-#else
-#define TUNE_BUCKETSIZE(h, multi)
-#endif
-
/* A hash bucket */
struct hbucket {
struct rcu_head rcu; /* for call_rcu */
@@ -936,7 +913,12 @@ mtype_add(struct ip_set *set, void *value, const struct ip_set_ext *ext,
goto set_full;
/* Create a new slot */
if (n->pos >= n->size) {
- TUNE_BUCKETSIZE(h, multi);
+#ifdef IP_SET_HASH_WITH_MULTI
+ if (h->bucketsize >= AHASH_MAX_TUNED)
+ goto set_full;
+ else if (h->bucketsize < multi)
+ h->bucketsize += AHASH_INIT_SIZE;
+#endif
if (n->size >= AHASH_MAX(h)) {
/* Trigger rehashing */
mtype_data_next(&h->next, d);
--
2.30.2
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