From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.216.51 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793896776; b=ef/DMjzizTH/FKNjl3VtQNdn0BQuoHzrob9kNbQ/yu2ySzqhqK8eo0HFfAFS0GNCxdAp bymmOJtVmlGxI9XZOBIf56WpM/OJKHV3GrGNfwM3/I76BIcypNz3BssRNdgXdg4Pk+jYf NujL9D+2tbnSbVzK6UPS6z8Sv5CEl2PHg0ka3MrelWLwTzEzKlxKNUioZbj2Iz4TmBBSb JxsyM9EbYzVF50JQh96ljYn6RAbT9/8cFWeJKfGFF3iLfIwITwrtEo5WfkfG9EmVWLsdV U47HWIdx9FlOXqIIN1OFmDwh0PGT3qvbe/ASBW2j1/r3rYmL1tTIveW5rFCNw0NZw5Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793896776; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: Content-Type:Date:Message-Id:Cc:Subject:From:To:In-Reply-To: References:Content-Transfer-Encoding:MIME-Version; bh=g7fNqjHpYaxkYpPES1WMA+c07Ra73ql25qOjXSvqWMg=; b=bfYklu9iDxMCdWAI/zOj2qahku6UlePQon1fqlMKlR+nLSHR4V9iouwrJ//mh+C8AMBY PV6QPxTCpM6DAaPKEAmtWMFJwvDgjR7he8JALQvvNNngJ+xNuVidBtTqWDTC97IyzaMaf WPWaeggZpVBJK4P40QxQ821IODn3qGwgfBD6qDRiHKa9NZZ+KDayA5g06ZIwd+sX/T4aj nOtnIOwu5M3B99mIUnLDGfAgKz2tbaa8S5Z4gjhHV4At4wDCGgg4vr6rgFDHPncQsXI03 J+VWq3HKKPWPQQgTuPv6VSO6dNdKGbpoElgaXCLG1polOAJrnd+oGzDf9W8aExGsdbA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=Do+25Wfz; arc=none smtp.remote-ip=209.85.216.51 Received: from mail-pj1-f51.google.com (mail-pj1-f51.google.com [209.85.216.51]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4BE9E606D80B for ; Thu, 5 Nov 2026 16:39:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 4BE9E606D80B 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, unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=Do+25Wfz Received: by mail-pj1-f51.google.com with SMTP id 98e67ed59e1d1-3b09c07b3d2so1255476a91.3 for ; Thu, 05 Nov 2026 08:39:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1793896771; x=1794501571; darn=vger.kernel.org; h=mime-version:content-transfer-encoding:references:in-reply-to:to :from:subject:cc:message-id:date:content-type:from:to:cc:subject :date:message-id:reply-to:content-type; bh=g7fNqjHpYaxkYpPES1WMA+c07Ra73ql25qOjXSvqWMg=; b=Do+25WfzhzV45gI604/1EZvOaKh/pike1eqCQMpc8ex4jx1pAN42T46xblK9HDKHB7 KBTnLQs3xSuJSR0+hEgKmeAUNfW7AALEE1T+rKSR8y/Wr6GUmZX+ZXbk0/jIIrWIb34e Yw9LpdxIJ6RYaq5C4Wj70gFPr5PfoFNw9Wj1rtSjpwyfXfGgNxmzpEWd+pGHumtKX+QO k215Bah+78+AZwfWVSUOu39cXJM1slYWKsGxQY1UQiXMh04MxQ3RMSH5gZw9oEmKn7eL 2b+IzsuxrHs07AWt0ROurkw62JUn2qAQga5a3MNxjUfuy3Fj7jBTvPwu5jCADAyjs7gl zT9w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1793896771; x=1794501571; h=mime-version:content-transfer-encoding:references:in-reply-to:to :from:subject:cc:message-id:date:content-type:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=g7fNqjHpYaxkYpPES1WMA+c07Ra73ql25qOjXSvqWMg=; b=i/lYdQvdW5qCsst1TYzRRXCKhu7dpb/DUhMZmdekcbS04Z+k6dQn4bDL6waAk53HVg VoqZ9tr6Ia/mBBMPQPeUOUgLwZ4aMr5tooidAUY4LyOLgrC4Ly+FEP9wX1YQPmZ6JW/g DIrNupGX89cmCJ9Ma2g2d6pderYJCIuhQ6cs82OydZzd4+Uf2i2+xOTah3DDUOD3GMvv wBSmMc91iyW3ebUx/LAfYyehsHfR8i6+wZq2w/D2z5cbvk0683V98TXzgRc5jfgwmuSy Rp/MDb1u8AlEa7QJ0PTdI3MMMa/NsYEWGq5NjIgQUfU7q2Nkdv98C5rZszCNGrXJdJAI KFrA== X-Forwarded-Encrypted: i=1; AKwUvBxABjTM+WezEvlhZPNKr/5jnjK8p3kVwlkOtThSuEaXcuTvIeeJNtfyDZmlscMnwn8x5nQ=@vger.kernel.org X-Gm-Message-State: APuU4Z8hb0LvPpX9oVEpK8mZxiCVSo6N2oVq827s7ImDob17Et7SnDwY yIry0v38fqyFrojdWlJnWkYdAg+BIIv528d7Wid/EaeR63fmqdvUGCQU X-Gm-Gg: AYBFou3qK1ArDWm2lgMOC8ijcukCMEzeHNhHRZCIOrLIOMMKFDPFLBdXdpzVnRJm+kz 7Kbg/f0PzUjCLjGyHMQ+kogWPuSGRrsvSpOx323U1yHGJzR9vojJy44zOSnwCso81PTevFoSUiB bmqMzS1UHtrDZ2FUZp+RahKZZ88Jxt8vTrrSF3gL5Sm8Ps9Mxu/39bwMX/6RIeJu01PGK2vadGO 5NclK2OWrjYWF4fe6lcuFdZE+pivHZ2jArZthNdm6cpdj7btw2o0PoXA7ym4u2pKJY+EVeS1cee 1fuH+SIbn/FRZPagaNIVtaqOC2+/BmHbzWdja3f5LQ3ey9MMZWJDN5WHUjKzej/W7bvoKxWUELv ghOOHqZ5Q45N4uMVz+buaITwfdRjP0t+nD8oaql6zZNJgxXaO/m8im0Gsdp9+ixmhV6jpo4WGAj v8aL9mKdCT2mdGH2i2YCCHO9lqaQ0I0k+gF2saeajWwQPSdtlpt2wN5R4hbDx67JUGfKI98OVcA 8KdG8FcIQKdh5mHoalvob0yiQSoEq4fx3u417hzjhG2wGkAP21cz3XqmZpHa/4BSAJXgS+bOUvJ 9BjxlVut5CXLyKJp8W6zUeiiRX7s+2idOLZnhdDUUrxDiDZXd/ja0pPlz+TJ2/ZPYAQ4BUBDfs4 I/JaPMhG6LXIf+gCKaX9c4aUyHomffBGeptY= X-Received: by 2002:a17:90b:4b8a:b0:3a7:8350:3f7e with SMTP id 98e67ed59e1d1-3ae89771679mr16239176a91.44.1793896770403; Thu, 05 Nov 2026 08:39:30 -0800 (PST) Received: from localhost ([153.61.198.243]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3b0b323cd47sm4574863a91.6.2026.11.05.08.39.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 05 Nov 2026 08:39:29 -0800 (PST) Content-Type: text/plain; charset=UTF-8 Date: Thu, 05 Nov 2026 16:39:29 +0000 Message-Id: Cc: , Subject: Re: [PATCH] bpf: Add network namespace boundary inspection kfuncs From: "Alexei Starovoitov" To: "Abhishek Khade" , , , In-Reply-To: <20261105121642.38019-1-abhishekkhade69@gmail.com> References: <20261105121642.38019-1-abhishekkhade69@gmail.com> Content-Transfer-Encoding: 8bit X-Mailing-List: bpf@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 On Thu, Nov 05, 2026 at 04:16 AM Abhishek Khade wrote: > Currently, dereferencing task->nsproxy->net_ns directly via BPF CO-RE > presents safety and architectural challenges: No. The prog does all of it today without new kfuncs: inum = task->nsproxy->net_ns->ns.inum; is_init_net = inum == NET_NS_INIT_INO; The verifier accepts these loads in tp_btf, fentry and lsm progs. A load that faults reads zero. It doesn't crash. NET_NS_INIT_INO is uapi. No need for the address of init_net. For a socket it's sk->__sk_common.skc_net.net->ns.inum. Networking progs also have bpf_get_netns_cookie(). > + rcu_read_lock(); > + nsproxy = rcu_dereference(task->nsproxy); > + if (nsproxy) { > + net = READ_ONCE(nsproxy->net_ns); > + if (net) > + inum = net->ns.inum; This is a use-after-free when task != current. So much for 'this is safer than CO-RE' :( pw-bot: cr