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Miller" , Sasha Levin Subject: [PATCH 6.1 0145/1887] openvswitch: prepare for stolen verdict coming from conntrack and nat engine Date: Wed, 28 Oct 2026 17:37:21 +0100 Message-ID: <20261028170502.536525682@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170459.200466217@linuxfoundation.org> References: <20261028170459.200466217@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Florian Westphal [ Upstream commit c7f79f2620b7776586c626edf21eb6ed6ed3d1eb ] At this time, conntrack either returns NF_ACCEPT or NF_DROP. To improve debuging it would be nice to be able to replace NF_DROP verdict with NF_DROP_REASON() helper, This helper releases the skb instantly (so drop_monitor can pinpoint precise location) and returns NF_STOLEN. Prepare call sites to deal with this before introducing such changes in conntrack and nat core. Signed-off-by: Florian Westphal Reviewed-by: Aaron Conole Signed-off-by: David S. Miller [Stable 6.1 adaptation: retain the local NAT implementation, which already updates the flow key only on NF_ACCEPT, and return before restoring skb headers on NF_STOLEN. Rename the existing OVS helper and pass its existing connection and ctinfo explicitly so the following helper-UAF fix can use the upstream call signature without importing the shared-helper refactor. Use a single-evaluation verdict_to_errno macro instead of adding a function. Remove the dead add_helper flag and align the helper-call condition with 1a4151e6be57; the flag was set only for unconfirmed connections but tested only for confirmed ones. The helper relocation itself remains in the target.] Stable-dep-of: 1a4151e6be57 ("net: openvswitch: conntrack: fix helper UAF due to extensions realloc") Signed-off-by: Sasha Levin --- net/openvswitch/conntrack.c | 56 ++++++++++++++++++++++--------------- 1 file changed, 34 insertions(+), 22 deletions(-) diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c index a7bb9e360ed37..8c5f6602af44a 100644 --- a/net/openvswitch/conntrack.c +++ b/net/openvswitch/conntrack.c @@ -435,16 +435,14 @@ static int ovs_ct_set_labels(struct nf_conn *ct, struct sw_flow_key *key, } /* 'skb' should already be pulled to nh_ofs. */ -static int ovs_ct_helper(struct sk_buff *skb, u16 proto) +static int nf_ct_helper(struct sk_buff *skb, struct nf_conn *ct, + enum ip_conntrack_info ctinfo, u16 proto) { const struct nf_conntrack_helper *helper; const struct nf_conn_help *help; - enum ip_conntrack_info ctinfo; unsigned int protoff; - struct nf_conn *ct; int err; - ct = nf_ct_get(skb, &ctinfo); if (!ct || ctinfo == IP_CT_RELATED_REPLY) return NF_ACCEPT; @@ -799,7 +797,7 @@ static void ovs_nat_update_key(struct sw_flow_key *key, /* Modelled after nf_nat_ipv[46]_fn(). * range is only used for new, uninitialized NAT state. - * Returns either NF_ACCEPT or NF_DROP. + * Returns NF_ACCEPT, NF_DROP or NF_STOLEN. */ static int ovs_ct_nat_execute(struct sk_buff *skb, struct nf_conn *ct, enum ip_conntrack_info ctinfo, @@ -874,6 +872,9 @@ static int ovs_ct_nat_execute(struct sk_buff *skb, struct nf_conn *ct, err = nf_nat_packet(ct, ctinfo, hooknum, skb); push: + if ((err & NF_VERDICT_MASK) == NF_STOLEN) + return err; + skb_push_rcsum(skb, nh_off); /* Update the flow key if NAT successful. */ @@ -951,6 +952,14 @@ static int ovs_ct_nat(struct net *net, struct sw_flow_key *key, } #endif +/* Translate netfilter verdicts without evaluating the argument twice. */ +#define verdict_to_errno(verdict) ({ \ + unsigned int __verdict = (verdict) & NF_VERDICT_MASK; \ + \ + __verdict == NF_ACCEPT ? 0 : \ + __verdict == NF_STOLEN ? -EINPROGRESS : -EINVAL; \ +}) + /* Pass 'skb' through conntrack in 'net', using zone configured in 'info', if * not done already. Update key with new CT state after passing the packet * through conntrack. @@ -1001,7 +1010,7 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key, err = nf_conntrack_in(skb, &state); if (err != NF_ACCEPT) - return -ENOENT; + return verdict_to_errno(err); /* Clear CT state NAT flags to mark that we have not yet done * NAT after the nf_conntrack_in() call. We can actually clear @@ -1015,8 +1024,6 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key, ct = nf_ct_get(skb, &ctinfo); if (ct) { - bool add_helper = false; - /* Packets starting a new connection must be NATted before the * helper, so that the helper knows about the NAT. We enforce * this by delaying both NAT and helper calls for unconfirmed @@ -1028,9 +1035,12 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key, * the key->ct_state. */ if (info->nat && !(key->ct_state & OVS_CS_F_NAT_MASK) && - (nf_ct_is_confirmed(ct) || info->commit) && - ovs_ct_nat(net, key, info, skb, ct, ctinfo) != NF_ACCEPT) { - return -EINVAL; + (nf_ct_is_confirmed(ct) || info->commit)) { + int err = ovs_ct_nat(net, key, info, skb, ct, ctinfo); + + err = verdict_to_errno(err); + if (err) + return err; } /* Userspace may decide to perform a ct lookup without a helper @@ -1045,7 +1055,6 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key, GFP_ATOMIC); if (err) return err; - add_helper = true; /* helper installed, add seqadj if NAT is required */ if (info->nat && !nfct_seqadj(ct)) { @@ -1055,15 +1064,15 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key, } /* Call the helper only if: - * - nf_conntrack_in() was executed above ("!cached") or a - * helper was just attached ("add_helper") for a confirmed - * connection, or + * - nf_conntrack_in() was executed above ("!cached"), or * - When committing an unconfirmed connection. */ - if ((nf_ct_is_confirmed(ct) ? !cached || add_helper : - info->commit) && - ovs_ct_helper(skb, info->family) != NF_ACCEPT) { - return -EINVAL; + if ((nf_ct_is_confirmed(ct) ? !cached : info->commit)) { + int err = nf_ct_helper(skb, ct, ctinfo, info->family); + + err = verdict_to_errno(err); + if (err) + return err; } if (nf_ct_protonum(ct) == IPPROTO_TCP && @@ -1291,10 +1300,9 @@ static int ovs_ct_commit(struct net *net, struct sw_flow_key *key, /* This will take care of sending queued events even if the connection * is already confirmed. */ - if (nf_conntrack_confirm(skb) != NF_ACCEPT) - return -EINVAL; + err = nf_conntrack_confirm(skb); - return 0; + return verdict_to_errno(err); } /* Trim the skb to the length specified by the IP/IPv6 header, @@ -1357,6 +1365,10 @@ int ovs_ct_execute(struct net *net, struct sk_buff *skb, else err = ovs_ct_lookup(net, key, info, skb); + /* conntrack core returned NF_STOLEN */ + if (err == -EINPROGRESS) + return err; + skb_push_rcsum(skb, nh_ofs); if (err) kfree_skb(skb); -- 2.53.0