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[v2,1/2] netfilter: nfnetlink: always ACK batch end if requested

Message ID 20251004092655.237888-2-nickgarlis@gmail.com
State Under Review
Headers show
Series always ACK batch end if requested | expand

Commit Message

Nikolaos Gkarlis Oct. 4, 2025, 9:26 a.m. UTC 
Before ACKs were introduced for batch begin and batch end messages,
userspace expected to receive the same number of ACKs as it sent,
unless a fatal error occurred.

To preserve this deterministic behavior, send an ACK for batch end
messages even when an error happens in the middle of the batch,
similar to how ACKs are handled for command messages.

Fixes: bf2ac490d28c ("netfilter: nfnetlink: Handle ACK flags for batch
messages")
Signed-off-by: Nikolaos Gkarlis <nickgarlis@gmail.com>
---
 net/netfilter/nfnetlink.c | 5 +++++
 1 file changed, 5 insertions(+)
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Patch

diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 811d02b4c4f7..33acc1b94a0e 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -600,6 +600,11 @@  static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
 			status |= NFNL_BATCH_FAILURE;
 			goto replay_abort;
 		}
+
+		if (nlh->nlmsg_flags & NLM_F_ACK && status & NFNL_BATCH_DONE) {
+			memset(&extack, 0, sizeof(extack));
+			nfnl_err_add(&err_list, nlh, 0, &extack);
+		}
 	}
 
 	nfnl_err_deliver(&err_list, oskb);