From patchwork Wed Nov 30 19:01:08 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Soheil Hassas Yeganeh X-Patchwork-Id: 701133 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3tTVBY1J9Tz9t0X for ; Thu, 1 Dec 2016 06:01:25 +1100 (AEDT) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="nDYGWUtr"; dkim-atps=neutral Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757574AbcK3TBT (ORCPT ); Wed, 30 Nov 2016 14:01:19 -0500 Received: from mail-qt0-f193.google.com ([209.85.216.193]:35577 "EHLO mail-qt0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755486AbcK3TBR (ORCPT ); Wed, 30 Nov 2016 14:01:17 -0500 Received: by mail-qt0-f193.google.com with SMTP id m48so20730155qta.2 for ; Wed, 30 Nov 2016 11:01:17 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=from:to:cc:subject:date:message-id; bh=8xKJrW+hHWggKxx22yk3rQZqOPkC/ygMakWR0yIQlkM=; b=nDYGWUtrusz3v27z1js3jNkqTAOYGC1M5WVIXRnPB+w5UoKDbTDZCR6dEvP1r1UdA1 xWuLWDocawyyBGhcNmtXmhYwEDpQKjjbMGGpmTbZukXEEKcUQC+YJy2cRibF4TGyIWBG CGHnpKhEW/wCvf+OlLpLYMsxOsyoQrzAIfwEaX1J7XvIntRwrf5LZlAI/9pa7o3RaEAz 4PuCQBmLcSh/bPXqgwRpQUGvvmQP7Jsu8+1nuAzZkqFdTxMvlM186mNjcgMC4nKVCeH+ hf3Tua/cCahHi95gqLw5qQCUpUK59DYcRiOaUsgBHD9+ayCJB5dh9bIg+4iRhj0u8q4A RrKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=8xKJrW+hHWggKxx22yk3rQZqOPkC/ygMakWR0yIQlkM=; b=AidmY28ektkg84zd1OcQiAXbZxdoP8N7Y7Y1MX9TE/hM3rCZyGLvcBEkn9vUMTEnRN qsJqLjoUtXaJNToeL3cHqymxQ/AfK8PAAPtWX3HfnyxRqXsdVcW88aKr0u0MFy8fzY7r PO9sLEloTRXYV6tIt9xKnqsYjot0WmEr283HSFFPq099oOkzCsaOnmU9F0Ru4q/pFYVK fxDIbH4R2M+zvuL0dU4b8msiGkl9VzX81LUvrgJjYd5g5Eng4jn8XJ9voHeIMZsXpX9a M7GuvXPKUAlcIcM9MlBKYIoCIrfqK9Pk4d7rJVmLQDgWcze8UUz/675vC6sNZVf1+SUj 39Rg== X-Gm-Message-State: AKaTC00URqBqYcb3NOpdZFSM2HrDDXTLxGLZkIz5HEEWPqk/9/bzaH+S+1O+xVmpbnhdbg== X-Received: by 10.237.55.72 with SMTP id i66mr33570625qtb.83.1480532471378; Wed, 30 Nov 2016 11:01:11 -0800 (PST) Received: from soheil.nyc.corp.google.com ([100.101.230.57]) by smtp.gmail.com with ESMTPSA id n31sm34094240qta.28.2016.11.30.11.01.10 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 30 Nov 2016 11:01:10 -0800 (PST) From: Soheil Hassas Yeganeh To: davem@davemloft.net, netdev@vger.kernel.org Cc: edumazet@google.com, willemb@google.com, maze@google.com, hannes@stressinduktion.org, Soheil Hassas Yeganeh Subject: [PATCH net-next] sock: reset sk_err for ICMP packets read from error queue Date: Wed, 30 Nov 2016 14:01:08 -0500 Message-Id: <1480532468-1610-1-git-send-email-soheil.kdev@gmail.com> X-Mailer: git-send-email 2.8.0.rc3.226.g39d4020 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Soheil Hassas Yeganeh Only when ICMP packets are enqueued onto the error queue, sk_err is also set. Before f5f99309fa74 (sock: do not set sk_err in sock_dequeue_err_skb), a subsequent error queue read would set sk_err to the next error on the queue, or 0 if empty. As no error types other than ICMP set this field, sk_err should not be modified upon dequeuing them. Only for ICMP errors, reset the (racy) sk_err. Some applications, like traceroute, rely on it and go into a futile busy POLLERR loop otherwise. In principle, sk_err has to be set while an ICMP error is queued. Testing is_icmp_err_skb(skb_next) approximates this without requiring a full queue walk. Applications that receive both ICMP and other errors cannot rely on this legacy behavior, as other errors do not set sk_err in the first place. Fixes: f5f99309fa74 (sock: do not set sk_err in sock_dequeue_err_skb) Signed-off-by: Soheil Hassas Yeganeh Signed-off-by: Willem de Bruijn Acked-by: Eric Dumazet Acked-by: Maciej Żenczykowski --- net/core/skbuff.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index d1d1a5a..8dad391 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3714,20 +3714,29 @@ int sock_queue_err_skb(struct sock *sk, struct sk_buff *skb) } EXPORT_SYMBOL(sock_queue_err_skb); +static bool is_icmp_err_skb(const struct sk_buff *skb) +{ + return skb && (SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP || + SKB_EXT_ERR(skb)->ee.ee_origin == SO_EE_ORIGIN_ICMP6); +} + struct sk_buff *sock_dequeue_err_skb(struct sock *sk) { struct sk_buff_head *q = &sk->sk_error_queue; - struct sk_buff *skb, *skb_next; + struct sk_buff *skb, *skb_next = NULL; + bool icmp_next = false; unsigned long flags; - int err = 0; spin_lock_irqsave(&q->lock, flags); skb = __skb_dequeue(q); if (skb && (skb_next = skb_peek(q))) - err = SKB_EXT_ERR(skb_next)->ee.ee_errno; + icmp_next = is_icmp_err_skb(skb_next); spin_unlock_irqrestore(&q->lock, flags); - if (err) + if (is_icmp_err_skb(skb) && !icmp_next) + sk->sk_err = 0; + + if (skb_next) sk->sk_error_report(sk); return skb;