netfilter: nf_tables: use u32 for chain use counter

Since 4fefee5 ("netfilter: nf_tables: allow to delete several objects
from a batch"), every new rule bumps the chain use counter. However,
this is limited to 16 bits, which means that it will overrun after
2^16 rules.

Use a u32 chain counter and check for overflows (just like we do for
table objects).

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 7ee6ce6..713b0b8 100644 (file)
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -503,9 +503,9 @@ enum nft_chain_flags {
  *     @net: net namespace that this chain belongs to
  *     @table: table that this chain belongs to
  *     @handle: chain handle
- *     @flags: bitmask of enum nft_chain_flags
  *     @use: number of jump references to this chain
  *     @level: length of longest path to this chain
+ *     @flags: bitmask of enum nft_chain_flags
  *     @name: name of the chain
  */
 struct nft_chain {
@@ -514,9 +514,9 @@ struct nft_chain {
        struct net                      *net;
        struct nft_table                *table;
        u64                             handle;
-       u8                              flags;
-       u16                             use;
+       u32                             use;
        u16                             level;
+       u8                              flags;
        char                            name[NFT_CHAIN_MAXNAMELEN];
 };
 

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index ba37c10..5586426 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1730,6 +1730,9 @@ static int nf_tables_newrule(struct sock *nlsk, struct sk_buff *skb,
                if (!create || nlh->nlmsg_flags & NLM_F_REPLACE)
                        return -EINVAL;
                handle = nf_tables_alloc_handle(table);
+
+               if (chain->use == UINT_MAX)
+                       return -EOVERFLOW;
        }
 
        if (nla[NFTA_RULE_POSITION]) {