From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f173.google.com (mail-pf1-f173.google.com [209.85.210.173]) (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 8695616DEB5; Mon, 9 Dec 2024 06:11:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.173 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733724691; cv=none; b=XlKJYIqaSWfyV+r4qE7rUG5m0wXIBGWxrhLTitKn1vmsmqmI8Xlh3ZGwp7mOHA198Fjx0YBI5RycaOTGm68UG8heEpIN10tqqHTY59UsDg+P+diGaOkqjGwziMhDGoLHYPsWXXe31MCVTXzkISL7yuOZlZwhey2fD47udi5Qiv8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733724691; c=relaxed/simple; bh=uWhiM+/cVZ+gZtMPzxGcN6fFIQWwYSzJU8wU6/NrLM4=; h=Date:From:To:Cc:Message-ID:In-Reply-To:References:Subject: Mime-Version:Content-Type; b=XFFxe6NAB+FK6lMBng7MWm9T31K4+wfM8IUDTPt/SH9+AnhnJwz1wl4I6dMJf+P7GWSD8fEnkTv2U4sAQ+yznhD5U9a1ntEdlum9tA1k1SNdJ292yqNQ3GjMu8aaiUvAtFr1QuDBJMoXJbMHvpcrmXoSvnAg7PmS/BGPud00eOc= 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=Hr4ihsZ2; arc=none smtp.client-ip=209.85.210.173 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="Hr4ihsZ2" Received: by mail-pf1-f173.google.com with SMTP id d2e1a72fcca58-725abf74334so3336778b3a.3; Sun, 08 Dec 2024 22:11:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1733724689; x=1734329489; 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=U0Dr18ok2Bwr1dMchDb8ArapEa4jmdw3PhKJpSV2ky8=; b=Hr4ihsZ24sMHXs4+qJsfYkG1SmnZSSagiHafDeth6ahrleft7MErLw2vwxrNIeDZHf PBDthx8ol4Mgj9cjhvXmDxnN1VcYuwZiWQ/+H5b99okXVD0JI2vHNLzWtXM+pBHlltHN QyuvfUgcwe62H/YbLylEly5rk7zfO6CqFTN9Szw4PusFgvxi35jB9IX+C1TvnNk6x9tE j/yl0jqgnpaw6QLOzyicJE4UrxR3JdG2a4vbwBhvLPcPyt5fd+JUptlntf4N3MTvXP8N wijicivmhD+jPzrOeo4FZf85WRFByjY2tjlM5KjpRO0jKid/E4KFmbrc7jONZjjgaA0S RO+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1733724689; x=1734329489; 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=U0Dr18ok2Bwr1dMchDb8ArapEa4jmdw3PhKJpSV2ky8=; b=esSc5nKfP+QNeC/lpuzReWIlFiABjOcx0PoCZZcfEIVZT0BnQD1IAmOY0S6RD84qYP Uq3AndS+S8rmuyayqdOf1D7YJuj9I5SNGovU7hPbXpanN6qTebLeIuj9YpKdrO/fZnVY kAXVC0vqCdLPev+VOXTv6UViDPQMI7URUuUuFk0rZ5RCd5ADC3qWA+imYRmp3SPNnhxw iKYDn7Pbq6EnC4zfXtvlPT3H/rGOuGBQVvaL5dhsXmhV1cXnMW/602iMyadSoEipz50T QkBhCOyChahXttsMYqcWkOex/bJIPZ7wFlyNXbLaVYjDLeZkK/bCn7nULrsogb9nsnF1 dWBA== X-Forwarded-Encrypted: i=1; AJvYcCV9rZaOgHjxNAtN45mMcwohlAaSZw74sns+cLPFd1piEFqFeVMeY7LI+2NdG3rRGI9hoZrl032d@vger.kernel.org, AJvYcCVHWVirEjGhzMrYeZdFNkSXRHACSQYPqE6+jDJ3F6bI874ECD804/VTOnO/A4uBGuVT1G2zjUKAgmbN9xE5fbs=@vger.kernel.org X-Gm-Message-State: AOJu0YxbuWyQXDN4jNY01n3B9aGCybky/MdGOvcnf48+2RS8ZgMVdvqn inlN0nOlDG0iwtm2TOnc8tQaigLNI8m5oLIE4GCugGvCchL0wjNC X-Gm-Gg: ASbGncsnUtxOQbnv01o5BIubqhhDUJL4PB26/vmSqCJLSarNXS1fVA9vAyp4jyrn89a YcOtrmKtfdTOw76B9ipBNU6op7NCXEXINdTp98ufW3QYuLM9pK8r/PzPjwPLZ1bsgl258omNU1H 7oLnEQexllFTkoRvUHPjLmT8rJOtFlbmvu9Es1vIWNJlEuJtQ1kxWOPg0QQgNZ0HfE02SgcFoMD xkJE4ja6M6rihyUcDS+5qiJUIuCJd6djMJBiackgdQuKvV6s48= X-Google-Smtp-Source: AGHT+IFMQfjWG8+hq0DsREnI77EtruDQsGNSS2eOzaYid2+5l3TTbMj5s/XqTwPKfy6itOzuf3pr4w== X-Received: by 2002:a05:6a00:a90:b0:725:f153:22d5 with SMTP id d2e1a72fcca58-725f1532457mr1897792b3a.18.1733724688664; Sun, 08 Dec 2024 22:11:28 -0800 (PST) Received: from localhost ([98.97.37.114]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-725c9ec7217sm3888129b3a.60.2024.12.08.22.11.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Dec 2024 22:11:27 -0800 (PST) Date: Sun, 08 Dec 2024 22:11:26 -0800 From: John Fastabend To: Michal Luczaj , Andrii Nakryiko , Eduard Zingerman , Mykola Lysenko , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Shuah Khan , Jakub Sitnicki , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman Cc: bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, netdev@vger.kernel.org, Michal Luczaj Message-ID: <67568a0ed36d3_1abf20818@john.notmuch> In-Reply-To: <20241202-sockmap-replace-v1-3-1e88579e7bd5@rbox.co> References: <20241202-sockmap-replace-v1-0-1e88579e7bd5@rbox.co> <20241202-sockmap-replace-v1-3-1e88579e7bd5@rbox.co> Subject: RE: [PATCH bpf 3/3] bpf, sockmap: Fix race between element replace and close() Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Michal Luczaj wrote: > Element replace (with a socket different from the one stored) may race with > socket's close() link popping & unlinking. __sock_map_delete() > unconditionally unrefs the (wrong) element: > > // set map[0] = s0 > map_update_elem(map, 0, s0) > > // drop fd of s0 > close(s0) > sock_map_close() > lock_sock(sk) (s0!) > sock_map_remove_links(sk) > link = sk_psock_link_pop() > sock_map_unlink(sk, link) > sock_map_delete_from_link > // replace map[0] with s1 > map_update_elem(map, 0, s1) > sock_map_update_elem > (s1!) lock_sock(sk) > sock_map_update_common > psock = sk_psock(sk) > spin_lock(&stab->lock) > osk = stab->sks[idx] > sock_map_add_link(..., &stab->sks[idx]) > sock_map_unref(osk, &stab->sks[idx]) > psock = sk_psock(osk) > sk_psock_put(sk, psock) > if (refcount_dec_and_test(&psock)) > sk_psock_drop(sk, psock) > spin_unlock(&stab->lock) > unlock_sock(sk) > __sock_map_delete > spin_lock(&stab->lock) > sk = *psk // s1 replaced s0; sk == s1 > if (!sk_test || sk_test == sk) // sk_test (s0) != sk (s1); no branch > sk = xchg(psk, NULL) > if (sk) > sock_map_unref(sk, psk) // unref s1; sks[idx] will dangle > psock = sk_psock(sk) > sk_psock_put(sk, psock) > if (refcount_dec_and_test()) > sk_psock_drop(sk, psock) > spin_unlock(&stab->lock) > release_sock(sk) > > Then close(map) enqueues bpf_map_free_deferred, which finally calls > sock_map_free(). This results in some refcount_t warnings along with a > KASAN splat[1]. > [...] > Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") > Signed-off-by: Michal Luczaj > --- > net/core/sock_map.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/net/core/sock_map.c b/net/core/sock_map.c > index 20b348b1964a10a1b0bfbe1a90a4a4cd99715b81..f1b9b3958792cd599efcb591742874e9b3f4a76b 100644 > --- a/net/core/sock_map.c > +++ b/net/core/sock_map.c > @@ -412,12 +412,11 @@ static void *sock_map_lookup_sys(struct bpf_map *map, void *key) > static int __sock_map_delete(struct bpf_stab *stab, struct sock *sk_test, > struct sock **psk) > { > - struct sock *sk; > + struct sock *sk = NULL; > int err = 0; > > spin_lock_bh(&stab->lock); > - sk = *psk; > - if (!sk_test || sk_test == sk) > + if (!sk_test || sk_test == *psk) > sk = xchg(psk, NULL); > > if (likely(sk)) > > -- > 2.46.2 > Reviewed-by: John Fastabend