From patchwork Tue Apr 2 10:46:21 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jakub Sitnicki X-Patchwork-Id: 13613710 X-Patchwork-Delegate: bpf@iogearbox.net Received: from mail-ej1-f54.google.com (mail-ej1-f54.google.com [209.85.218.54]) (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 4E9F258AB2 for ; Tue, 2 Apr 2024 10:46:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.218.54 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712054787; cv=none; b=Ei/6HMGlUYRRMsH4Gr8LSmIvhoAZx47XCJY3hWFkdZnQd8Wyp6QzLoNMfnDBwASrFt9yVSLKb5nAIUrHMeEIHbl43hkXB6nopw8QTxW7c8QosOZLk4yAD+2yG0WAuAShXVof8rMkEkLFCJNQQY/VIYERt4fiP5lmUgVmYa54vP0= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712054787; c=relaxed/simple; bh=a4x5CfomU36qJDm28YUJczEo/IKK9GxkHsyKpqEFbtk=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=pdjLNmdA1wSNNH8/f33Tlo9hwK7jEigpVWezE27LOLPmgEVuMDw8x7UrBMZvMb0nkmmAADwqMuvx1q9j9avKTrxXTF0CAtE5rN1UiG1yxC1ISLMXbH2ein39Y5F6ZYL604aRCIuwEtWpMBRplg9h7CfI8DiwEJ6c8ELfB2X9me4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=cloudflare.com; spf=pass smtp.mailfrom=cloudflare.com; dkim=pass (2048-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b=amt/SM6Q; arc=none smtp.client-ip=209.85.218.54 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=cloudflare.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=cloudflare.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="amt/SM6Q" Received: by mail-ej1-f54.google.com with SMTP id a640c23a62f3a-a466fc8fcccso629886666b.1 for ; Tue, 02 Apr 2024 03:46:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google09082023; t=1712054783; x=1712659583; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=3HwOQm2QT2sV95LcMqWAOOKr4NlLIHjYeX2vrN7lg4c=; b=amt/SM6QFAmW9dB6Cv4PZARUaMhVffvwZs+roDbIDmshnLYJeJVKwxS0yXDUZeob9Y R/DpuBTqP8HkETdYNQo6YzT9AYsQWT3FT2gSr8cPhxiMGLdfYX4Uu16whKNoDd0D+FFi yxqt5NZ8FqKYX3s006D6RoDDvA+0TwdDUT573ZFkVKboV3PcpKt36tmHoYIKi9OcdCDQ wAz1BLX9NyGRM5hMg9ZgPg/zj0TOXUqJ7GQN9zxkdgth68HPpFeq4SL5/iZLGFdG4+dK 3y9Ouq7QPHrIbSh6PySrmYlFRVgSdDVIECCC+yMfBZt6BVA6gVlJyQE8t7QOXwG3xXr3 5S3w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1712054783; x=1712659583; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=3HwOQm2QT2sV95LcMqWAOOKr4NlLIHjYeX2vrN7lg4c=; b=qiZ5VRwKr29W8Vue92JP3jV1Np4Xv9dUZvf3QfdP+E1jCQXjWEmkrQqt1yDBk+l3Ws /8WCDtbHgPz8+ha3gkTkkKQIEyiefnMzkNCS6VCUk8RsXXKgB2kCBeVlsP4m0uRde36y jc25+h1nQ/6B8QI1FvfnCt050srrSjTsfvCc9QDf2uHhOttQqCCQ4ujhlEqvwmuNCo33 X5yNU4I0guck2y0VxaxMoCvWM5c+OnjJrJBwRfDhMTC2QnKT7CnwAhhmWHqhtgAluML2 cLp8r58CF/dCRt/+dQH5VXw0kBHaU2ok46eUc3tGOXHk0G7brPnk2pRv/YLp/MR+/PXi GOhw== X-Gm-Message-State: AOJu0YxptawTwVj879FsQB3Osd2yRzu+tNrNxFpktloq43wkLrI5P/9n zuM21yq9TNyAeG20NiBCR7xz4x02j0sCy8CIcIsslqglpK8+Qx3BTIIogSe+2KEW4nAIyD+eezg q X-Google-Smtp-Source: AGHT+IEXTMyfRcLzPfwri3XrvvIXecjUm2Huax5dBU7LBSpiv1p4D8HJoK0+qYZYri/9VWGbgrOnTw== X-Received: by 2002:a17:906:bcf7:b0:a4d:f927:f747 with SMTP id op23-20020a170906bcf700b00a4df927f747mr7174006ejb.4.1712054783029; Tue, 02 Apr 2024 03:46:23 -0700 (PDT) Received: from cloudflare.com ([2a09:bac5:5064:2dc::49:17e]) by smtp.gmail.com with ESMTPSA id zh11-20020a170906880b00b00a4e48e52ecbsm4129404ejb.198.2024.04.02.03.46.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Apr 2024 03:46:22 -0700 (PDT) From: Jakub Sitnicki To: bpf@vger.kernel.org Cc: netdev@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , kernel-team@cloudflare.com, xingwei lee , yue sun , syzbot+bc922f476bd65abbd466@syzkaller.appspotmail.com, syzbot+d4066896495db380182e@syzkaller.appspotmail.com, John Fastabend , Edward Adam Davis , Shung-Hsi Yu Subject: [PATCH bpf] bpf, sockmap: Prevent lock inversion deadlock in map delete elem Date: Tue, 2 Apr 2024 12:46:21 +0200 Message-ID: <20240402104621.1050319-1-jakub@cloudflare.com> X-Mailer: git-send-email 2.44.0 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net syzkaller started using corpuses where a BPF tracing program deletes elements from a sockmap/sockhash map. Because BPF tracing programs can be invoked from any interrupt context, locks taken during a map_delete_elem operation must be hardirq-safe. Otherwise a deadlock due to lock inversion is possible, as reported by lockdep: CPU0 CPU1 ---- ---- lock(&htab->buckets[i].lock); local_irq_disable(); lock(&host->lock); lock(&htab->buckets[i].lock); lock(&host->lock); Locks in sockmap are hardirq-unsafe by design. We expects elements to be deleted from sockmap/sockhash only in task (normal) context with interrupts enabled, or in softirq context. Detect when map_delete_elem operation is invoked from a context which is _not_ hardirq-unsafe, that is interrupts are disabled, and bail out with an error. Note that map updates are not affected by this issue. BPF verifier does not allow updating sockmap/sockhash from a BPF tracing program today. Reported-by: xingwei lee Reported-by: yue sun Reported-by: syzbot+bc922f476bd65abbd466@syzkaller.appspotmail.com Reported-and-tested-by: syzbot+d4066896495db380182e@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=d4066896495db380182e Closes: https://syzkaller.appspot.com/bug?extid=bc922f476bd65abbd466 Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") Signed-off-by: Jakub Sitnicki Acked-by: John Fastabend --- Cc: John Fastabend Cc: Edward Adam Davis Cc: Shung-Hsi Yu --- net/core/sock_map.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/net/core/sock_map.c b/net/core/sock_map.c index 27d733c0f65e..8598466a3805 100644 --- a/net/core/sock_map.c +++ b/net/core/sock_map.c @@ -411,6 +411,9 @@ static int __sock_map_delete(struct bpf_stab *stab, struct sock *sk_test, struct sock *sk; int err = 0; + if (irqs_disabled()) + return -EOPNOTSUPP; /* locks here are hardirq-unsafe */ + spin_lock_bh(&stab->lock); sk = *psk; if (!sk_test || sk_test == sk) @@ -933,6 +936,9 @@ static long sock_hash_delete_elem(struct bpf_map *map, void *key) struct bpf_shtab_elem *elem; int ret = -ENOENT; + if (irqs_disabled()) + return -EOPNOTSUPP; /* locks here are hardirq-unsafe */ + hash = sock_hash_bucket_hash(key, key_size); bucket = sock_hash_select_bucket(htab, hash);