From patchwork Mon Feb 12 00:13:40 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vadim Fedorenko X-Patchwork-Id: 13552652 X-Patchwork-Delegate: kuba@kernel.org Received: from mx0a-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B54431FA2 for ; Mon, 12 Feb 2024 00:14:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=67.231.153.30 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707696860; cv=none; b=Voe8CDntf+ks3S9jO8w+uWVa1MFIpux676bMnKB+XGiauCcOz+cnSyudJKdSU3TrvDarDbnzYAFMdweq32RdOw18gXHZKi0zZDKqv9NdTCiiXySrtElvlA0E9vvhNFihxEGRQQw9TW8d8cv04fJD6iiyOqlJMLqmJbvQDeZ9HcI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707696860; c=relaxed/simple; bh=eLIsbCedowxgdSXIKSQfV7nbIVK1gCViK7g55DvvGuU=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=QIZgnU7dNYRR6AfCeyg1yHwaoxth4Ou407pz0c3p8+qTE9ibExhEBwTveDuDWQJbB9Brs1qI/vIV7BlSpCE1gzNzuIqEn1Mpk8pX3YZX2aT4VgRwfhZw2YaXseVK5I7QbAZuJ6uzao8gT0771ICbm8wItlLpRmeUSm7QUrEvgGQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=meta.com; spf=pass smtp.mailfrom=meta.com; dkim=pass (2048-bit key) header.d=meta.com header.i=@meta.com header.b=Vid30Fsn; arc=none smtp.client-ip=67.231.153.30 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=meta.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=meta.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=meta.com header.i=@meta.com header.b="Vid30Fsn" Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.17.1.19/8.17.1.19) with ESMTP id 41BAXvGY024674; Sun, 11 Feb 2024 16:13:53 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=meta.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=s2048-2021-q4; bh=v3XUaLn04Rzdj34drqI45QHI0Vj31Iv2ZKt+SSxDH4o=; b=Vid30Fsn7qQ1brAVF2uwgM960xdTcYgjBoY+lP2jzKkGzHXNw0yGGxMowd2oclpRWyu0 3TzkXHYux527noZOrDe6jecJ/Ri/XQG2xfuySsMmWeMOk7Yx4fE+EHVgyJC61uop3/2r nD5/03z5XaDg4W8sdWND3Ugs8IEUFDvYbEG+fSbVKUEFHJBeXz1AE9F4BN95aIL4ckA8 FP4rNQa6bl7ix9uw7YYEo8W8ebsloOpkXY93O1bDyN9i98s4pLIhqB0VHhPn2kAdmA6f KByKqcMUxSb1THvpUL3AA6RD4NIc4jyM69pth/PB388+8ZG39ixy0bBGk/gJnSZy0HbI pA== Received: from mail.thefacebook.com ([163.114.132.120]) by m0089730.ppops.net (PPS) with ESMTPS id 3w65hfw9jc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Sun, 11 Feb 2024 16:13:53 -0800 Received: from devvm4158.cln0.facebook.com (2620:10d:c085:108::8) by mail.thefacebook.com (2620:10d:c085:11d::8) with Microsoft SMTP Server id 15.1.2507.35; Sun, 11 Feb 2024 16:13:50 -0800 From: Vadim Fedorenko To: Vadim Fedorenko , Willem de Bruijn , Andy Lutomirski CC: Vadim Fedorenko , Jakub Kicinski , "David S . Miller" , Willem de Bruijn , Subject: [PATCH net v2] net-timestamp: make sk_tskey more predictable in error path Date: Sun, 11 Feb 2024 16:13:40 -0800 Message-ID: <20240212001340.1719944-1-vadfed@meta.com> X-Mailer: git-send-email 2.39.3 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Proofpoint-GUID: 22guu4yYPwqaFWnoI3Q-RMR_1ZeSOImB X-Proofpoint-ORIG-GUID: 22guu4yYPwqaFWnoI3Q-RMR_1ZeSOImB X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-02-11_22,2024-02-08_01,2023-05-22_02 X-Patchwork-Delegate: kuba@kernel.org When SOF_TIMESTAMPING_OPT_ID is used to ambiguate timestamped datagrams, the sk_tskey can become unpredictable in case of any error happened during sendmsg(). Move increment later in the code and make decrement of sk_tskey in error path. This solution is still racy in case of multiple threads doing snedmsg() over the very same socket in parallel, but still makes error path much more predictable. Fixes: 09c2d251b707 ("net-timestamp: add key to disambiguate concurrent datagrams") Reported-by: Andy Lutomirski Signed-off-by: Vadim Fedorenko --- net/ipv4/ip_output.c | 14 +++++++++----- net/ipv6/ip6_output.c | 14 +++++++++----- 2 files changed, 18 insertions(+), 10 deletions(-) diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c index 41537d18eecf..ac4995ed17c7 100644 --- a/net/ipv4/ip_output.c +++ b/net/ipv4/ip_output.c @@ -974,7 +974,7 @@ static int __ip_append_data(struct sock *sk, struct rtable *rt = (struct rtable *)cork->dst; unsigned int wmem_alloc_delta = 0; bool paged, extra_uref = false; - u32 tskey = 0; + u32 tsflags, tskey = 0; skb = skb_peek_tail(queue); @@ -982,10 +982,6 @@ static int __ip_append_data(struct sock *sk, mtu = cork->gso_size ? IP_MAX_MTU : cork->fragsize; paged = !!cork->gso_size; - if (cork->tx_flags & SKBTX_ANY_TSTAMP && - READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID) - tskey = atomic_inc_return(&sk->sk_tskey) - 1; - hh_len = LL_RESERVED_SPACE(rt->dst.dev); fragheaderlen = sizeof(struct iphdr) + (opt ? opt->optlen : 0); @@ -1052,6 +1048,11 @@ static int __ip_append_data(struct sock *sk, cork->length += length; + tsflags = READ_ONCE(sk->sk_tsflags); + if (cork->tx_flags & SKBTX_ANY_TSTAMP && + tsflags & SOF_TIMESTAMPING_OPT_ID) + tskey = atomic_inc_return(&sk->sk_tskey) - 1; + /* So, what's going on in the loop below? * * We use calculated fragment length to generate chained skb, @@ -1274,6 +1275,9 @@ static int __ip_append_data(struct sock *sk, cork->length -= length; IP_INC_STATS(sock_net(sk), IPSTATS_MIB_OUTDISCARDS); refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc); + if (cork->tx_flags & SKBTX_ANY_TSTAMP && + tsflags & SOF_TIMESTAMPING_OPT_ID) + atomic_dec(&sk->sk_tskey); return err; } diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index a722a43dd668..42e423012c18 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1422,7 +1422,7 @@ static int __ip6_append_data(struct sock *sk, int err; int offset = 0; bool zc = false; - u32 tskey = 0; + u32 tsflags, tskey = 0; struct rt6_info *rt = (struct rt6_info *)cork->dst; struct ipv6_txoptions *opt = v6_cork->opt; int csummode = CHECKSUM_NONE; @@ -1440,10 +1440,6 @@ static int __ip6_append_data(struct sock *sk, mtu = cork->gso_size ? IP6_MAX_MTU : cork->fragsize; orig_mtu = mtu; - if (cork->tx_flags & SKBTX_ANY_TSTAMP && - READ_ONCE(sk->sk_tsflags) & SOF_TIMESTAMPING_OPT_ID) - tskey = atomic_inc_return(&sk->sk_tskey) - 1; - hh_len = LL_RESERVED_SPACE(rt->dst.dev); fragheaderlen = sizeof(struct ipv6hdr) + rt->rt6i_nfheader_len + @@ -1538,6 +1534,11 @@ static int __ip6_append_data(struct sock *sk, flags &= ~MSG_SPLICE_PAGES; } + tsflags = READ_ONCE(sk->sk_tsflags); + if (cork->tx_flags & SKBTX_ANY_TSTAMP && + tsflags & SOF_TIMESTAMPING_OPT_ID) + tskey = atomic_inc_return(&sk->sk_tskey) - 1; + /* * Let's try using as much space as possible. * Use MTU if total length of the message fits into the MTU. @@ -1794,6 +1795,9 @@ static int __ip6_append_data(struct sock *sk, cork->length -= length; IP6_INC_STATS(sock_net(sk), rt->rt6i_idev, IPSTATS_MIB_OUTDISCARDS); refcount_add(wmem_alloc_delta, &sk->sk_wmem_alloc); + if (cork->tx_flags & SKBTX_ANY_TSTAMP && + tsflags & SOF_TIMESTAMPING_OPT_ID) + atomic_dec(&sk->sk_tskey); return err; }