From: Andrii Melnychenko <a.melnychenko@vyos.io> stable inclusion from stable-v5.10.253 commit 83273af0b60c093ba0085c205864d8542e1b1653 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/14592 CVE: CVE-2026-43060 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 90918e3b6404c2a37837b8f11692471b4c512de2 ] Sequence adjustment may be required for FTP traffic with PASV/EPSV modes. due to need to re-write packet payload (IP, port) on the ftp control connection. This can require changes to the TCP length and expected seq / ack_seq. The easiest way to reproduce this issue is with PASV mode. Example ruleset: table inet ftp_nat { ct helper ftp_helper { type "ftp" protocol tcp l3proto inet } chain prerouting { type filter hook prerouting priority 0; policy accept; tcp dport 21 ct state new ct helper set "ftp_helper" } } table ip nat { chain prerouting { type nat hook prerouting priority -100; policy accept; tcp dport 21 dnat ip prefix to ip daddr map { 192.168.100.1 : 192.168.13.2/32 } } chain postrouting { type nat hook postrouting priority 100 ; policy accept; tcp sport 21 snat ip prefix to ip saddr map { 192.168.13.2 : 192.168.100.1/32 } } } Note that the ftp helper gets assigned *after* the dnat setup. The inverse (nat after helper assign) is handled by an existing check in nf_nat_setup_info() and will not show the problem. Topoloy: +-------------------+ +----------------------------------+ | FTP: 192.168.13.2 | <-> | NAT: 192.168.13.3, 192.168.100.1 | +-------------------+ +----------------------------------+ | +-----------------------+ | Client: 192.168.100.2 | +-----------------------+ ftp nat changes do not work as expected in this case: Connected to 192.168.100.1. [..] ftp> epsv EPSV/EPRT on IPv4 off. ftp> ls 227 Entering passive mode (192,168,100,1,209,129). 421 Service not available, remote server has closed connection. Kernel logs: Missing nfct_seqadj_ext_add() setup call WARNING: CPU: 1 PID: 0 at net/netfilter/nf_conntrack_seqadj.c:41 [..] __nf_nat_mangle_tcp_packet+0x100/0x160 [nf_nat] nf_nat_ftp+0x142/0x280 [nf_nat_ftp] help+0x4d1/0x880 [nf_conntrack_ftp] nf_confirm+0x122/0x2e0 [nf_conntrack] nf_hook_slow+0x3c/0xb0 .. Fix this by adding the required extension when a conntrack helper is assigned to a connection that has a nat binding. Fixes: 1a64edf54f55 ("netfilter: nft_ct: add helper set support") Signed-off-by: Andrii Melnychenko <a.melnychenko@vyos.io> Signed-off-by: Florian Westphal <fw@strlen.de> Stable-dep-of: 36eae0956f65 ("netfilter: nft_ct: drop pending enqueued packets on removal") Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Dong Chenchen \u003cdongchenchen2@huawei.com\u003e --- net/netfilter/nft_ct.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/netfilter/nft_ct.c b/net/netfilter/nft_ct.c index 32b83333e834..2fa47efba081 100644 --- a/net/netfilter/nft_ct.c +++ b/net/netfilter/nft_ct.c @@ -22,6 +22,7 @@ #include <net/netfilter/nf_conntrack_timeout.h> #include <net/netfilter/nf_conntrack_l4proto.h> #include <net/netfilter/nf_conntrack_expect.h> +#include <net/netfilter/nf_conntrack_seqadj.h> struct nft_ct { enum nft_ct_keys key:8; @@ -1105,6 +1106,10 @@ static void nft_ct_helper_obj_eval(struct nft_object *obj, if (help) { rcu_assign_pointer(help->helper, to_assign); set_bit(IPS_HELPER_BIT, &ct->status); + + if ((ct->status & IPS_NAT_MASK) && !nfct_seqadj(ct)) + if (!nfct_seqadj_ext_add(ct)) + regs->verdict.code = NF_DROP; } } -- 2.43.0