path: root/include
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authorFlorian Westphal <fw@strlen.de>2020-08-20 21:05:50 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2020-08-21 19:00:33 +0200
commit1e105e6afa6c3d32bfb52c00ffa393894a525c27 (patch)
tree441667450a5963c044c83b1492530a12eb04a054 /include
parentnetfilter: nf_tables: incorrect enum nft_list_attributes definition (diff)
netfilter: nf_tables: fix destination register zeroing
Following bug was reported via irc: nft list ruleset set knock_candidates_ipv4 { type ipv4_addr . inet_service size 65535 elements = { . 123, . 123 } } .. udp dport 123 add @knock_candidates_ipv4 { ip saddr . 123 } udp dport 123 add @knock_candidates_ipv4 { ip saddr . udp dport } It should not have been possible to add a duplicate set entry. After some debugging it turned out that the problem is the immediate value (123) in the second-to-last rule. Concatenations use 32bit registers, i.e. the elements are 8 bytes each, not 6 and it turns out the kernel inserted inet firewall @knock_candidates_ipv4 element 0100007f ffff7b00 : 0 [end] element 0100007f 00007b00 : 0 [end] Note the non-zero upper bits of the first element. It turns out that nft_immediate doesn't zero the destination register, but this is needed when the length isn't a multiple of 4. Furthermore, the zeroing in nft_payload is broken. We can't use [len / 4] = 0 -- if len is a multiple of 4, index is off by one. Skip zeroing in this case and use a conditional instead of (len -1) / 4. Fixes: 49499c3e6e18 ("netfilter: nf_tables: switch registers to 32 bit addressing") Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'include')
1 files changed, 2 insertions, 0 deletions
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index bf9491b77d16..224d194ad29d 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -143,6 +143,8 @@ static inline u64 nft_reg_load64(const u32 *sreg)
static inline void nft_data_copy(u32 *dst, const struct nft_data *src,
unsigned int len)
+ if (len % NFT_REG32_SIZE)
+ dst[len / NFT_REG32_SIZE] = 0;
memcpy(dst, src, len);