5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Fabian Bläse fabian@blaese.de
[ Upstream commit c6dd1aa2cbb72b33e0569f3e71d95792beab5042 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv4/icmp.c | 6 ++++-- net/ipv6/ip6_icmp.c | 6 ++++-- 2 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c index ac82a4158b86b..875424c428e66 100644 --- a/net/ipv4/icmp.c +++ b/net/ipv4/icmp.c @@ -790,11 +790,12 @@ void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) struct sk_buff *cloned_skb = NULL; struct ip_options opts = { 0 }; enum ip_conntrack_info ctinfo; + enum ip_conntrack_dir dir; struct nf_conn *ct; __be32 orig_ip;
ct = nf_ct_get(skb_in, &ctinfo); - if (!ct || !(ct->status & IPS_SRC_NAT)) { + if (!ct || !(READ_ONCE(ct->status) & IPS_NAT_MASK)) { __icmp_send(skb_in, type, code, info, &opts); return; } @@ -809,7 +810,8 @@ void icmp_ndo_send(struct sk_buff *skb_in, int type, int code, __be32 info) goto out;
orig_ip = ip_hdr(skb_in)->saddr; - ip_hdr(skb_in)->saddr = ct->tuplehash[0].tuple.src.u3.ip; + dir = CTINFO2DIR(ctinfo); + ip_hdr(skb_in)->saddr = ct->tuplehash[dir].tuple.src.u3.ip; __icmp_send(skb_in, type, code, info, &opts); ip_hdr(skb_in)->saddr = orig_ip; out: diff --git a/net/ipv6/ip6_icmp.c b/net/ipv6/ip6_icmp.c index 9e3574880cb03..233914b63bdb8 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: