From: Florian Westphal fw@strlen.de
[ Upstream commit 1e105e6afa6c3d32bfb52c00ffa393894a525c27 ]
Following bug was reported via irc: nft list ruleset set knock_candidates_ipv4 { type ipv4_addr . inet_service size 65535 elements = { 127.0.0.1 . 123, 127.0.0.1 . 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 Signed-off-by: Sasha Levin sashal@kernel.org --- include/net/netfilter/nf_tables.h | 2 ++ net/netfilter/nft_payload.c | 4 +++- 2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h index 024636c31adcf..93253ba1eeac3 100644 --- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -130,6 +130,8 @@ static inline u8 nft_reg_load8(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); }
diff --git a/net/netfilter/nft_payload.c b/net/netfilter/nft_payload.c index 19446a89a2a81..b1a9f330a51fe 100644 --- a/net/netfilter/nft_payload.c +++ b/net/netfilter/nft_payload.c @@ -79,7 +79,9 @@ static void nft_payload_eval(const struct nft_expr *expr, u32 *dest = ®s->data[priv->dreg]; int offset;
- dest[priv->len / NFT_REG32_SIZE] = 0; + if (priv->len % NFT_REG32_SIZE) + dest[priv->len / NFT_REG32_SIZE] = 0; + switch (priv->base) { case NFT_PAYLOAD_LL_HEADER: if (!skb_mac_header_was_set(skb))