From patchwork Wed Feb 5 15:51:12 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Dumazet X-Patchwork-Id: 13961422 X-Patchwork-Delegate: kuba@kernel.org Received: from mail-qv1-f74.google.com (mail-qv1-f74.google.com [209.85.219.74]) (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 592051990B7 for ; Wed, 5 Feb 2025 15:51:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.219.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738770689; cv=none; b=erMDvkzxVqZ3vIa90b1W1fCN78hy2AzO4xGAVV1Ud08lLG6IqEjRMC/6//KoZs7kFgt3qGfGmCoUVh9D/4nwViadlddLCWUWuPW+vvtvyi4pnXHu/XkSLjb+18UqgTb3oOdl5MkOP2YM4I7fmoVwCNWigYYARnC8v7XXtq46NoU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738770689; c=relaxed/simple; bh=H8JH/QPjFfGxbrJtRbDkCum9cREuE5YKVIPC//b1qCs=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=NfqpYY1QtHdgrhpUUx1VWyUXm6KsX0c+djPuHgVTCI9JRQXQT2xtS4sg2sGoSmoMuf8g7+hqDdHZUbVwkFnVuZGnFaUKH48gI0K2sZ+73nL1L852QEsGUxmkFUcFkoRG8Z0PoGSA1KhIAq7iBwG9Y3DpZc7N1yxGXQ+9I3m5Sxg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=QMjxGcj9; arc=none smtp.client-ip=209.85.219.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--edumazet.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="QMjxGcj9" Received: by mail-qv1-f74.google.com with SMTP id 6a1803df08f44-6e42e3cb051so34681686d6.0 for ; Wed, 05 Feb 2025 07:51:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1738770687; x=1739375487; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=oummPnO89bchIzAktiowh3Jl3EZAt201EnCE7gdN6jc=; b=QMjxGcj9tjQY49Q9wI4gGwaNbVLqo5wCMAmYjoPqBJpuTntYyvRQ7N5D0pYwDXS2Li ZfcXKMDIliCEP9Ps4Gzhnr/FZE7VNozQ025BklcsWafxVG3qtG8RVhTLSGMXrNdJRqkj n2ZgHyPQxyPYof4dTHyRbgfuqj0Tm1BC1+atOOTOl7TNzixd1mNEXZNx48KGLGf3qu5j 5iGmADe+pMuR/ZP69Ao3wz1xu3Kav5UK3l3fu6OLucciHbErkMl8al8MTq8qU8m4kabM ybvqYP7xTzfqe1Zr2nGwe+ZSJw2zeddeOivbhWRty8HRBkF3acdXs9UPZjyBe9q/cvH8 gToQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1738770687; x=1739375487; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=oummPnO89bchIzAktiowh3Jl3EZAt201EnCE7gdN6jc=; b=SnyFk+3elcJ6gfTlubrX+nD5ymQT80R0SUjRt23nkn4uoe/VJD44oyz4w42puCP0LK t0ipiLIBVqc7BlC25aDetahUORQ7jYnJyUrbKiZqlxgko/u5TMW8tF9IA8SFioBGzXmB zSzdcG7Iyj5nD2En+EZOe3k6irRiccJt3dou59+Q9J4eQu2uZriaSidfbPTqOnrII/ev AeRZqi1rrWf5a3rD6g4EgyL5VeYQ9f6/BrrL+s+2peSGxZ/a6ktJTIl7nENG6J39rKTA xeWw0tWD7fGw8Fit7V95C59jMKY1OUXZJtGVd9MdQTWtLEgCynDNPivDW0I9+UHSiLZO 4MxQ== X-Gm-Message-State: AOJu0YwBK1q+Nc2JhLQtRPxMRED60XAsJZL/eplxHIlySmKz+wZkbywH ppcIGxFor97xJpLnV+KDw0MZe/4dZk2jLRLemiSn97p+KZ1qh+kL5K/smT7LziZs1Jg3SZ7LOHv olpeAfkJ37w== X-Google-Smtp-Source: AGHT+IEED/sXUFR8e5BcIPk0aFSPDj3FXn4V8c/ldayogRX7uDzKvpe0Hxl6B9psUVHWEAUTHY5p0BRxkYT+LQ== X-Received: from qknru10.prod.google.com ([2002:a05:620a:684a:b0:7bc:de89:fc31]) (user=edumazet job=prod-delivery.src-stubby-dispatcher) by 2002:a05:620a:43a6:b0:7b6:753b:9b5d with SMTP id af79cd13be357-7c03a036f63mr575155085a.36.1738770687191; Wed, 05 Feb 2025 07:51:27 -0800 (PST) Date: Wed, 5 Feb 2025 15:51:12 +0000 In-Reply-To: <20250205155120.1676781-1-edumazet@google.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250205155120.1676781-1-edumazet@google.com> X-Mailer: git-send-email 2.48.1.362.g079036d154-goog Message-ID: <20250205155120.1676781-5-edumazet@google.com> Subject: [PATCH v4 net 04/12] ipv4: use RCU protection in ipv4_default_advmss() From: Eric Dumazet To: "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: netdev@vger.kernel.org, Kuniyuki Iwashima , Simon Horman , eric.dumazet@gmail.com, Eric Dumazet X-Patchwork-Delegate: kuba@kernel.org ipv4_default_advmss() must use RCU protection to make sure the net structure it reads does not disappear. Fixes: 2e9589ff809e ("ipv4: Namespaceify min_adv_mss sysctl knob") Signed-off-by: Eric Dumazet Reviewed-by: Kuniyuki Iwashima --- net/ipv4/route.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 577b88a43293aa801c3ee736d7e5cc4d97917717..74c074f45758be5ae78a87edb31837481cc40278 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1307,10 +1307,15 @@ static void set_class_tag(struct rtable *rt, u32 tag) static unsigned int ipv4_default_advmss(const struct dst_entry *dst) { - struct net *net = dev_net(dst->dev); unsigned int header_size = sizeof(struct tcphdr) + sizeof(struct iphdr); - unsigned int advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size, - net->ipv4.ip_rt_min_advmss); + unsigned int advmss; + struct net *net; + + rcu_read_lock(); + net = dev_net_rcu(dst->dev); + advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size, + net->ipv4.ip_rt_min_advmss); + rcu_read_unlock(); return min(advmss, IPV4_MAX_PMTU - header_size); }