diff options
| author | Fabian Bläse <fabian@blaese.de> | 2025-08-28 11:14:35 +0200 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2025-09-01 12:54:41 -0700 |
| commit | c6dd1aa2cbb72b33e0569f3e71d95792beab5042 (patch) | |
| tree | c8510e43a193fc8dd450585a35e36969a6507398 /net/ipv6/ip6_icmp.c | |
| parent | 7000f4fa9b24ae2511b07babd0d49e888db5d265 (diff) | |
icmp: fix icmp_ndo_send address translation for reply direction
The icmp_ndo_send function was originally introduced to ensure proper
rate limiting when icmp_send is called by a network device driver,
where the packet's source address may have already been transformed
by SNAT.
However, the original implementation only considers the
IP_CT_DIR_ORIGINAL direction for SNAT and always replaced the packet's
source address with that of the original-direction tuple. This causes
two problems:
1. For SNAT:
Reply-direction packets were incorrectly translated using the source
address of the CT original direction, even though no translation is
required.
2. For DNAT:
Reply-direction packets were not handled at all. In DNAT, the original
direction's destination is translated. Therefore, in the reply
direction the source address must be set to the reply-direction
source, so rate limiting works as intended.
Fix this by using the connection direction to select the correct tuple
for source address translation, and adjust the pre-checks to handle
reply-direction packets in case of DNAT.
Additionally, wrap the `ct->status` access in READ_ONCE(). This avoids
possible KCSAN reports about concurrent updates to `ct->status`.
Fixes: 0b41713b6066 ("icmp: introduce helper for nat'd source address in network device context")
Signed-off-by: Fabian Bläse <fabian@blaese.de>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'net/ipv6/ip6_icmp.c')
| -rw-r--r-- | net/ipv6/ip6_icmp.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/net/ipv6/ip6_icmp.c b/net/ipv6/ip6_icmp.c index 9e3574880cb0..233914b63bdb 100644 --- a/net/ipv6/ip6_icmp.c +++ b/net/ipv6/ip6_icmp.c @@ -54,11 +54,12 @@ void icmpv6_ndo_send(struct sk_buff *skb_in, u8 type, u8 code, __u32 info) struct inet6_skb_parm parm = { 0 }; struct sk_buff *cloned_skb = NULL; enum ip_conntrack_info ctinfo; + enum ip_conntrack_dir dir; struct in6_addr orig_ip; struct nf_conn *ct; ct = nf_ct_get(skb_in, &ctinfo); - if (!ct || !(ct->status & IPS_SRC_NAT)) { + if (!ct || !(READ_ONCE(ct->status) & IPS_NAT_MASK)) { __icmpv6_send(skb_in, type, code, info, &parm); return; } @@ -73,7 +74,8 @@ void icmpv6_ndo_send(struct sk_buff *skb_in, u8 type, u8 code, __u32 info) goto out; orig_ip = ipv6_hdr(skb_in)->saddr; - ipv6_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.in6; + dir = CTINFO2DIR(ctinfo); + ipv6_hdr(skb_in)->saddr = ct->tuplehash[dir].tuple.src.u3.in6; __icmpv6_send(skb_in, type, code, info, &parm); ipv6_hdr(skb_in)->saddr = orig_ip; out: |