From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.56 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793618368; b=eJm8rsgetcFO1SAHWEoIVODggXTvBiISOxtj5sMmFEPR5hgh6/2+F3C8X7jOMpKt/jXq wXMEyv1y3XgeoRpUUflOCZWGK23Z9Cz4fAN89LKuARx+Ozyb80/ZmVq0tlUbgWWgynvQA boHUn0kF4aiGctaqBXTzwDvcNMbqI8yA5Kb7ACOuIW7oqqdc+qqXRHEH0mYfKGA0YhFlU tafSX62mm7ZLkCjwU/L6zXwkUxkZCvx6x++c+qZMfl1XRuqUriuprRJOvLmTGyOWqMhOG gtwJxVy9oGSGQ5wUSy8wgbFYWDxpPPUCFGXzXssxjzd8x1a2C77hYxCdYjZIwEygrog== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793618368; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:From:In-Reply-To:Content-Type: Content-Transfer-Encoding; bh=dRXNIv+DjYJ9+xKJw7sbi+h+wlCEfvAUG5KDSY1I8Bs=; b=WckEuQDJOWklw9iju/pCSyV+tY7AK0iiKNAvx/5UpNK+vl2bmPu+a18Ynuemmg3GDHtV wmP4QzSzA2FWtwFNlslpikaMX8pFG0q11ylYMlMOh36AebLbTGvkM9IfW4fft89tre9UA 9QQTev+osPJHEBR5Uu3c1Tfu/y6CNysXp1lqnodip5sHWLzh28QJ5maNVIrOSNiYXxqmI 8I3VzwG1Vbj+u1PCVWcFQRSNIkLBXlsc/hkuErCLHjzOcwK3tY6aGCjA8y84dHEGcg25j GiRdAl681JvNTJOEM4JgW6P21qA12htBQdJCWlVu2Bn9YDAk2z2kBR1SbK9+P2wb3oQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=IxGU5tNT; arc=none smtp.remote-ip=95.215.58.56 Received: from mta1.migadu.com (out-56.mta1.migadu.com [95.215.58.56]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 08E3F606A326 for ; Mon, 2 Nov 2026 11:19:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 08E3F606A326 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=IxGU5tNT X-Envelope-To: mptcp@lists.linux.dev DKIM-Signature: a=rsa-sha256; bh=kdrMq5KnZifKZQNMAwZlFHNok5RGWVsm3UzqOukQXj4=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793618359; v=1; x=1794223159; b=IxGU5tNTW00mxD1061NSfytTWBcJgf2THMlRUiwpR0NtaICUnmDdp/LaCuJ2J15yN6mAwZ+I takgOxP7DoJJQU4mc+WQ9EPYCaOaWaETfCWG4k9WB+ZlooddlsE4eqM9Kaae8V7IqMyO0VNgYN1 qsXQvE5rLy1rax1Y9mK1Ev/A= X-Envelope-To: mptcp@lists.linux.dev Received: by smtp.migadu.com with ESMTPS id 4f07de2689d355c0; Mon, 02 Nov 2026 11:19:18 +0000 X-Mizu-Trace-ID: 4f07de2689d355c0 X-Migadu-Flow: FLOW_OUT Message-ID: Date: Mon, 2 Nov 2026 19:19:09 +0800 X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf v2 04/15] bpf, sockmap: Subtract all dropped bytes from the return value To: Alexei Starovoitov , bpf@vger.kernel.org, netdev@vger.kernel.org Cc: daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, john.fastabend@gmail.com, jakub@cloudflare.com, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, kuniyu@google.com, willemb@google.com, matttbe@kernel.org, mptcp@lists.linux.dev, mason@kernel.org, josef@toxicpanda.com References: <20261102072112.4160195-1-alexei.starovoitov@gmail.com> <20261102072112.4160195-5-alexei.starovoitov@gmail.com> From: Jiayuan Chen In-Reply-To: <20261102072112.4160195-5-alexei.starovoitov@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 11/2/26 3:21 PM, Alexei Starovoitov wrote: > From: Alexei Starovoitov > > When an sk_msg prog returns SK_DROP, tcp_bpf_send_verdict() frees the full > message. It then subtracts tosend bytes from *copied, the return value of > sendmsg(). But tosend is the number of bytes that the verdict applies to. > After bpf_msg_apply_bytes() tosend can be less than the message size. Then > sendmsg() reports dropped bytes as sent. > > Subtract the number of bytes that sk_msg_free() frees. After an error the > SK_PASS branch already does this. The SK_REDIRECT branch does the same if > the message is not the cork. Nothing changes when tosend is equal to the > message size. Otherwise sendmsg() now returns -EACCES if it sends nothing. > > Fixes: ca70b8baf2bd ("tcp_bpf: Fix the sk_mem_uncharge logic in tcp_bpf_sendmsg") > Signed-off-by: Alexei Starovoitov Reviewed-by: Jiayuan Chen > --- > net/ipv4/tcp_bpf.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c > index b016aa419fb2..36d1bf46353a 100644 > --- a/net/ipv4/tcp_bpf.c > +++ b/net/ipv4/tcp_bpf.c > @@ -521,12 +521,12 @@ static int tcp_bpf_send_verdict(struct sock *sk, struct sk_psock *psock, > break; > case __SK_DROP: > default: > - sk_msg_free(sk, msg); > + /* All of it is thrown away, not only tosend bytes */ > + *copied -= sk_msg_free(sk, msg) + delta; > sk_msg_apply_bytes(psock, tosend); > /* The verdict holds for apply_bytes, not for ever */ > if (!psock->apply_bytes) > psock->eval = __SK_NONE; > - *copied -= (tosend + delta); > return -EACCES; > } >