netdev - [PATCH 2/3] [RFC] bpf: allow non-TCP skbs for bpf_sock_ops_enable_tx

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Message-ID: <4c44029f32c3e6d5e3190e1f5687a604ebeafdff.1743337403.git.pav@iki.fi>
Date: Sun, 30 Mar 2025 15:23:37 +0300
From: Pauli Virtanen <pav@....fi>
To: linux-bluetooth@...r.kernel.org
Cc: Pauli Virtanen <pav@....fi>,
	netdev@...r.kernel.org,
	bpf@...r.kernel.org,
	willemdebruijn.kernel@...il.com,
	kerneljasonxing@...il.com
Subject: [PATCH 2/3] [RFC] bpf: allow non-TCP skbs for bpf_sock_ops_enable_tx_tstamp

Change bpf_sock_ops_enable_tx_tstamp() kfunc to only set SKBTX_BPF flag,
so that it can be used also for non-TCP skbs.  Do not set TCP-specific
fields if the socket is not TCP.

***

Doing it this way requires a valid tskey is set by the socket family,
before BPF_SOCK_OPS_TSTAMP_SENDMSG_CB.  Alternatively, it maybe could be
hardcoded per socket type here, or some new proto_ops added.
---
 net/core/filter.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 46ae8eb7a03c..1300b0ef3620 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -12127,6 +12127,7 @@ __bpf_kfunc int bpf_sk_assign_tcp_reqsk(struct __sk_buff *s, struct sock *sk,
 __bpf_kfunc int bpf_sock_ops_enable_tx_tstamp(struct bpf_sock_ops_kern *skops,
 					      u64 flags)
 {
+	struct sock *sk;
 	struct sk_buff *skb;
 
 	if (skops->op != BPF_SOCK_OPS_TSTAMP_SENDMSG_CB)
@@ -12135,10 +12136,17 @@ __bpf_kfunc int bpf_sock_ops_enable_tx_tstamp(struct bpf_sock_ops_kern *skops,
 	if (flags)
 		return -EINVAL;
 
+	sk = skops->sk;
+	if (!sk)
+		return -EINVAL;
+
 	skb = skops->skb;
 	skb_shinfo(skb)->tx_flags |= SKBTX_BPF;
-	TCP_SKB_CB(skb)->txstamp_ack |= TSTAMP_ACK_BPF;
-	skb_shinfo(skb)->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
+
+	if (sk_is_tcp(sk)) {
+		TCP_SKB_CB(skb)->txstamp_ack |= TSTAMP_ACK_BPF;
+		skb_shinfo(skb)->tskey = TCP_SKB_CB(skb)->seq + skb->len - 1;
+	}
 
 	return 0;
 }
-- 
2.49.0