[PATCH bpf v2 1/2] bpf, sockmap: Account for receive queue in FIONREAD without a verdict program
From: Mattia Meleleo via B4 Relay <devnull+mattia.meleleo.coralogix.com@kernel.org>
Date: 2026-07-08 13:42:00
Also in:
b4-sent, bpf
Subsystem:
bpf [l7 framework] (sockmap), networking [general], networking [tcp], the rest · Maintainers:
John Fastabend, Jakub Sitnicki, Jiayuan Chen, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds
From: Mattia Meleleo <redacted>
tcp_bpf_ioctl() answers SIOCINQ from psock->msg_tot_len, which only
counts bytes in ingress_msg. Without a stream/skb verdict program
nothing is diverted there: data stays in sk_receive_queue, so FIONREAD
returns 0 even though read() returns data.
Add tcp_inq() to the reported value when the psock has no verdict
program. The two queues are disjoint, so bytes redirected into
ingress_msg from other sockets stay correctly accounted through
msg_tot_len.
Fixes: 929e30f93125 ("bpf, sockmap: Fix FIONREAD for sockmap")
Reviewed-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Signed-off-by: Mattia Meleleo <redacted>
---
net/ipv4/tcp_bpf.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index cc0bd73f3..8e905b50d 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c@@ -334,6 +334,7 @@ static int tcp_bpf_recvmsg_parser(struct sock *sk, static int tcp_bpf_ioctl(struct sock *sk, int cmd, int *karg) { + struct sk_psock *psock; bool slow; if (cmd != SIOCINQ)
@@ -344,7 +345,21 @@ static int tcp_bpf_ioctl(struct sock *sk, int cmd, int *karg) return -EINVAL; slow = lock_sock_fast(sk); - *karg = sk_psock_msg_inq(sk); + psock = sk_psock_get(sk); + if (unlikely(!psock)) { + unlock_sock_fast(sk, slow); + return tcp_ioctl(sk, cmd, karg); + } + *karg = sk_psock_get_msg_len_nolock(psock); + /* Without a verdict program, ingress data is never diverted to + * ingress_msg: it stays in sk_receive_queue and is read through + * the fallback to tcp_recvmsg(), so account for it like + * tcp_ioctl() does. + */ + if (!READ_ONCE(psock->progs.stream_verdict) && + !READ_ONCE(psock->progs.skb_verdict)) + *karg += tcp_inq(sk); + sk_psock_put(sk, psock); unlock_sock_fast(sk, slow); return 0;
--
Git-155)