From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f172.google.com (mail-pl1-f172.google.com [209.85.214.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2E9231FA1; Tue, 9 Jul 2024 01:24:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720488253; cv=none; b=jMm+alZiy2GiMWbXtEkeknlwWNZO0mQUpxNncqxTwf5tfx7BYqkiWydnuEFRtBP6uUulTk1Rf+sqDFlRdcMnFeXOQrcCla9A4mLfgntMvzXK9Cp1dpiULHFkW7eGeCNJ4jWcxPn0zBYMHRIjkK2YxhSTvyeEY1vO2PJem6+vo+0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720488253; c=relaxed/simple; bh=lEtixa07+RUJAtKBJsg+gVwNeRwl/kAxLHxDaZOtyBc=; h=Date:From:To:Cc:Message-ID:In-Reply-To:References:Subject: Mime-Version:Content-Type; b=GT02zNLhLL4LyT1D/j0cAXqsZrZ7afNODIlBuzqTXLeuGQ/e4F01B2VInvd8b6LW33a/wDzTaRLhk82ybfYQTBiH6Gw9PwsAyhnX3pOOAaSsE1FyOZRNgMbKkBuNTe7syUkcUEYqAi9+QGieF+HTcBpcXBvCfIuKRdqtre5kQ2g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=kW0u2twX; arc=none smtp.client-ip=209.85.214.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="kW0u2twX" Received: by mail-pl1-f172.google.com with SMTP id d9443c01a7336-1fb3e9e32ffso18655905ad.0; Mon, 08 Jul 2024 18:24:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1720488250; x=1721093050; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:subject:references :in-reply-to:message-id:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=j32VYAlsuK3/jNbvHCaSgNRDqiz9cqS48fKSFKyyisg=; b=kW0u2twX+VFqsTFO15BewePKAqaLuWCifmH8wS6Wy/cdkidOocsgFZTo1NhDZS5sbX +oXsP3dIVHXHMuGKJGQ2agj3cuL+ULBSWx1JnvykihLei/pY4MVbPYWwR87wgzoAC/VE EJNqR8nLZqSXSeAKhtSvuvL7iG/DXFVNrf1ez6EBVEtbB2r3KIwmpl9V2shuI30HZOmm GucHQxLmvqN4NnEZyUCFLyRVzM2naFaiI7rqEhfXAF433FXXCgbH3fFYf03H/yb3PlcU ECQ5ue2AGcSlGep1sR4Xl2coKbXzMygqXEMIjaf1KXqdUwuFymHWFgwfE7cvEJ+IS+5u HUDg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1720488250; x=1721093050; h=content-transfer-encoding:mime-version:subject:references :in-reply-to:message-id:cc:to:from:date:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=j32VYAlsuK3/jNbvHCaSgNRDqiz9cqS48fKSFKyyisg=; b=Y/ePHyrMtN591MEapUfjDK6/ETFUcqymRBA7Xrwuwbwo4OYpocRSILdb+PhNV2of7P XM85+a3PYZI6TJWBz/C3OL/KS4x00iCIxtYYXHJ/SnHunMvSeBhUueBHzD5CGDu3Boa1 tkmQSGF9ZndLwGlyEJL0GYJq9ada0kPp76KtBzxiq1hKgdG4GBVOglgjboLEmPapGsWM 8evKcp/ZQe13yCiWFFE5Jy9JwRHZGVPOzkxwHibw9E6OdwTY9apknL392uTB/OGxvj5M rR3+Ya2JwdKhORk80LK82QUz8PIQuTNpN2sy4A6OH7K2O2Scg/pTM+Y7ZvB3UP/3dooX QLAA== X-Forwarded-Encrypted: i=1; AJvYcCVEqyYE5fqbSvyhy261tLkU/sctONqYGys3ObRxI3X3Q3Oa6SwlXowO8KljL8IcaPDt8ggJ8ku6GRLMY0FeuqWfN6LY4UQEEQfGtzIqLkhenanZjguD88Sro9p8 X-Gm-Message-State: AOJu0Yyn+RL8ubd5mEKsR61zBclfOUOvfVJhR7orEz4QcfU4bFod/3oW yVWRco00IdsD/mlM+XefkYcS1ose62dvwYi01r9te1841S2LnNXZRCcoMQ== X-Google-Smtp-Source: AGHT+IGd9SsKvaiwytVNuNwMiS1lxE3xnM6kDjIqPA7QoodzrYTEMUqV6/sjV5+BiL4ED9bplPS4nQ== X-Received: by 2002:a17:903:11d1:b0:1fa:2760:c3f3 with SMTP id d9443c01a7336-1fbb6d252a9mr9620375ad.13.1720488250411; Mon, 08 Jul 2024 18:24:10 -0700 (PDT) Received: from localhost ([98.97.32.172]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1fbb6a28f8esm4814595ad.64.2024.07.08.18.24.03 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Jul 2024 18:24:08 -0700 (PDT) Date: Mon, 08 Jul 2024 18:24:02 -0700 From: John Fastabend To: Kuniyuki Iwashima , mhal@rbox.co Cc: Rao.Shoaib@oracle.com, bpf@vger.kernel.org, cong.wang@bytedance.com, davem@davemloft.net, edumazet@google.com, jakub@cloudflare.com, john.fastabend@gmail.com, kuba@kernel.org, kuniyu@amazon.com, netdev@vger.kernel.org, pabeni@redhat.com Message-ID: <668c9132195f6_d7720840@john.notmuch> In-Reply-To: <20240708193820.3392-1-kuniyu@amazon.com> References: <20240707222842.4119416-2-mhal@rbox.co> <20240708193820.3392-1-kuniyu@amazon.com> Subject: Re: [PATCH bpf v3 1/4] af_unix: Disable MSG_OOB handling for sockets in sockmap/sockhash Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Kuniyuki Iwashima wrote: > From: Michal Luczaj > Date: Sun, 7 Jul 2024 23:28:22 +0200 > > AF_UNIX socket tracks the most recent OOB packet (in its receive queue) > > with an `oob_skb` pointer. BPF redirecting does not account for that: when > > an OOB packet is moved between sockets, `oob_skb` is left outdated. This > > results in a single skb that may be accessed from two different sockets. > > > > Take the easy way out: silently drop MSG_OOB data targeting any socket that > > is in a sockmap or a sockhash. Note that such silent drop is akin to the > > fate of redirected skb's scm_fp_list (SCM_RIGHTS, SCM_CREDENTIALS). > > > > For symmetry, forbid MSG_OOB in unix_bpf_recvmsg(). > > > > Suggested-by: Kuniyuki Iwashima > > Fixes: 314001f0bf92 ("af_unix: Add OOB support") > > Signed-off-by: Michal Luczaj > Why does af_unix put the oob data on the sk_receive_queue()? Wouldn't it be enough to just have the ousk->oob_skb hold the reference to the skb? I think for TCP/UDP at least I'll want to handle MSG_OOB data correctly. For redirect its probably fine to just drop or skip it, but when we are just reading recv msgs and parsing/observing it would be nice to not change how the application works. In practice I don't recall anyone reporting issues on TCP side though from incorrectly handling URG data. >From TCP side I believe we can fix the OOB case by checking the oob queue before doing the recvmsg handling. If the urg data wasn't on the general sk_receive_queue we could do similar here for af_unix? My argument for URG not working for redirect would be to let userspace handle it if they cared. Thanks. > Reviewed-by: Kuniyuki Iwashima > > Thanks! > > > > --- > > net/unix/af_unix.c | 41 ++++++++++++++++++++++++++++++++++++++++- > > net/unix/unix_bpf.c | 3 +++ > > 2 files changed, 43 insertions(+), 1 deletion(-) > > > > diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c > > index 142f56770b77..11cb5badafb6 100644 > > --- a/net/unix/af_unix.c > > +++ b/net/unix/af_unix.c > > @@ -2667,10 +2667,49 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk, > > > > static int unix_stream_read_skb(struct sock *sk, skb_read_actor_t recv_actor) > > { > > + struct unix_sock *u = unix_sk(sk); > > + struct sk_buff *skb; > > + int err; > > + > > if (unlikely(READ_ONCE(sk->sk_state) != TCP_ESTABLISHED)) > > return -ENOTCONN; > > > > - return unix_read_skb(sk, recv_actor); > > + mutex_lock(&u->iolock); > > + skb = skb_recv_datagram(sk, MSG_DONTWAIT, &err); > > + mutex_unlock(&u->iolock); > > + if (!skb) > > + return err; > > + > > +#if IS_ENABLED(CONFIG_AF_UNIX_OOB) > > + if (unlikely(skb == READ_ONCE(u->oob_skb))) { > > + bool drop = false; > > + > > + unix_state_lock(sk); > > + > > + if (sock_flag(sk, SOCK_DEAD)) { > > + unix_state_unlock(sk); > > + kfree_skb(skb); > > + return -ECONNRESET; > > + } > > + > > + spin_lock(&sk->sk_receive_queue.lock); > > + if (likely(skb == u->oob_skb)) { > > + WRITE_ONCE(u->oob_skb, NULL); > > + drop = true; > > + } > > + spin_unlock(&sk->sk_receive_queue.lock); > > + > > + unix_state_unlock(sk); > > + > > + if (drop) { > > + WARN_ON_ONCE(skb_unref(skb)); > > + kfree_skb(skb); > > + return -EAGAIN; > > + } > > + } > > +#endif > > + > > + return recv_actor(sk, skb); > > } > > > > static int unix_stream_read_generic(struct unix_stream_read_state *state, > > diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c > > index bd84785bf8d6..bca2d86ba97d 100644 > > --- a/net/unix/unix_bpf.c > > +++ b/net/unix/unix_bpf.c > > @@ -54,6 +54,9 @@ static int unix_bpf_recvmsg(struct sock *sk, struct msghdr *msg, > > struct sk_psock *psock; > > int copied; > > > > + if (flags & MSG_OOB) > > + return -EOPNOTSUPP; > > + > > if (!len) > > return 0; > > > > -- > > 2.45.2