From patchwork Thu Jul 6 23:25:47 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Xu X-Patchwork-Id: 13304298 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 E0E3116427; Thu, 6 Jul 2023 23:26:21 +0000 (UTC) Received: from out3-smtp.messagingengine.com (out3-smtp.messagingengine.com [66.111.4.27]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 52F351BC9; Thu, 6 Jul 2023 16:26:20 -0700 (PDT) Received: from compute2.internal (compute2.nyi.internal [10.202.2.46]) by mailout.nyi.internal (Postfix) with ESMTP id 2FB8A5C00C2; Thu, 6 Jul 2023 19:26:17 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute2.internal (MEProxy); Thu, 06 Jul 2023 19:26:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=dxuuu.xyz; h=cc :cc:content-transfer-encoding:content-type:date:date:from:from :in-reply-to:message-id:mime-version:reply-to:sender:subject :subject:to:to; s=fm1; t=1688685977; x=1688772377; bh=ILwmPPxacB L9zHkUCRnVdWlL4Glqz4GoyWt1wwCPYNE=; b=oX2Lbacu5ZaiB4hPXiUf3PTxaa Z+2UiyVyluT96v6omjhkLL5pzeKuECXV2JAUrCOkn6gD+UTlznPXzrUrr8KlQIRa M0u0DGIKKW67iE/Qs5EyiEY15DqI5raRd6z3BsBI5R5Ftywgycm4o0Hh8ft06UY9 jA7m48wenNlkcSHxSJTYYmGxGEJF6auz75ExNEGa/Oncn6JEV0BDR7IPrQkip3cZ ptioHTXIxx4PRCartqeV81ekU0uPa8ZkS5s6Fr4FRqX/hJe+lboN+oi/4MWsGNHt 9oc4CZ8WDA8Cu8LMTp/49Mn8L4Ay0WtF3Jfrf9I+IKwUwBVG8zWfU5v3/hXA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:cc:content-transfer-encoding :content-type:date:date:feedback-id:feedback-id:from:from :in-reply-to:message-id:mime-version:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm2; t=1688685977; x=1688772377; bh=ILwmPPxacBL9z HkUCRnVdWlL4Glqz4GoyWt1wwCPYNE=; b=a7U9Y5pXlK/McK3TuGOYrQCbp1qlZ Gc2bY5/kUSE7PhsCRqJoetcE8jaO2QKkwztLsr/QQHNcQpJ/QufTI47DX6XurzzA V/arE28UuMHIkYVXhkePMzDgd0obl4/Vn8fciCOFw+XqPzd8BlWRGr+D0iWFqWWR iaGz85OUKhDYIqHraDxuqm9gRrlu0mRR5hL+1bl5fhcHC7h5wb4CRm+Gc+iZjRuV nrg+s0x93s+0OOJm+F+HfhoHGJnkOWLSqGSHn1J+eblu9iIpiUXncXp81rknJfzF 9kD1DJ8hT77oAVstRVYFhUJj8MfApkySOslL2SbUX3FcuteuctjabBpXQ== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedviedrvddtgddvudcutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecufghrlhcuvffnffculdefhedmnecujfgurhephffvve fufffkofgggfestdekredtredttdenucfhrhhomhepffgrnhhivghlucgiuhcuoegugihu segugihuuhhurdighiiiqeenucggtffrrghtthgvrhhnpeetgefhhfeigfejtddvteefff fgteekteduiedtkeevleduvdejueeggfdtfeegfeenucffohhmrghinhepihgvthhfrdho rhhgnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehmrghilhhfrhhomhepug iguhesugiguhhuuhdrgiihii X-ME-Proxy: Feedback-ID: i6a694271:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 6 Jul 2023 19:26:15 -0400 (EDT) From: Daniel Xu To: netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, bpf@vger.kernel.org, coreteam@netfilter.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, fw@strlen.de, daniel@iogearbox.net Cc: dsahern@kernel.org Subject: [PATCH bpf-next v2 0/6] Support defragmenting IPv(4|6) packets in BPF Date: Thu, 6 Jul 2023 17:25:47 -0600 Message-ID: X-Mailer: git-send-email 2.41.0 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,SPF_HELO_PASS, SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: bpf@iogearbox.net === Context === In the context of a middlebox, fragmented packets are tricky to handle. The full 5-tuple of a packet is often only available in the first fragment which makes enforcing consistent policy difficult. There are really only two stateless options, neither of which are very nice: 1. Enforce policy on first fragment and accept all subsequent fragments. This works but may let in certain attacks or allow data exfiltration. 2. Enforce policy on first fragment and drop all subsequent fragments. This does not really work b/c some protocols may rely on fragmentation. For example, DNS may rely on oversized UDP packets for large responses. So stateful tracking is the only sane option. RFC 8900 [0] calls this out as well in section 6.3: Middleboxes [...] should process IP fragments in a manner that is consistent with [RFC0791] and [RFC8200]. In many cases, middleboxes must maintain state in order to achieve this goal. === BPF related bits === Policy has traditionally been enforced from XDP/TC hooks. Both hooks run before kernel reassembly facilities. However, with the new BPF_PROG_TYPE_NETFILTER, we can rather easily hook into existing netfilter reassembly infra. The basic idea is we bump a refcnt on the netfilter defrag module and then run the bpf prog after the defrag module runs. This allows bpf progs to transparently see full, reassembled packets. The nice thing about this is that progs don't have to carry around logic to detect fragments. === Changelog === Changes from v1: * Drop bpf_program__attach_netfilter() patches * static -> static const where appropriate * Fix callback assignment order during registration * Only request_module() if callbacks are missing * Fix retval when modprobe fails in userspace * Fix v6 defrag module name (nf_defrag_ipv6_hooks -> nf_defrag_ipv6) * Simplify priority checking code * Add warning if module doesn't assign callbacks in the future * Take refcnt on module while defrag link is active [0]: https://datatracker.ietf.org/doc/html/rfc8900 Daniel Xu (6): netfilter: defrag: Add glue hooks for enabling/disabling defrag netfilter: bpf: Support BPF_F_NETFILTER_IP_DEFRAG in netfilter link netfilter: bpf: Prevent defrag module unload while link active bpf: selftests: Support not connecting client socket bpf: selftests: Support custom type and proto for client sockets bpf: selftests: Add defrag selftests include/linux/netfilter.h | 15 + include/uapi/linux/bpf.h | 5 + net/ipv4/netfilter/nf_defrag_ipv4.c | 17 +- net/ipv6/netfilter/nf_defrag_ipv6_hooks.c | 11 + net/netfilter/core.c | 6 + net/netfilter/nf_bpf_link.c | 149 ++++++++- tools/include/uapi/linux/bpf.h | 5 + tools/testing/selftests/bpf/Makefile | 4 +- .../selftests/bpf/generate_udp_fragments.py | 90 ++++++ .../selftests/bpf/ip_check_defrag_frags.h | 57 ++++ tools/testing/selftests/bpf/network_helpers.c | 26 +- tools/testing/selftests/bpf/network_helpers.h | 3 + .../bpf/prog_tests/ip_check_defrag.c | 282 ++++++++++++++++++ .../selftests/bpf/progs/ip_check_defrag.c | 104 +++++++ 14 files changed, 752 insertions(+), 22 deletions(-) create mode 100755 tools/testing/selftests/bpf/generate_udp_fragments.py create mode 100644 tools/testing/selftests/bpf/ip_check_defrag_frags.h create mode 100644 tools/testing/selftests/bpf/prog_tests/ip_check_defrag.c create mode 100644 tools/testing/selftests/bpf/progs/ip_check_defrag.c