From patchwork Thu Mar 17 16:58:24 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jakub Sitnicki X-Patchwork-Id: 12784324 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1211C43219 for ; Thu, 17 Mar 2022 16:58:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236724AbiCQQ77 (ORCPT ); Thu, 17 Mar 2022 12:59:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236718AbiCQQ7v (ORCPT ); Thu, 17 Mar 2022 12:59:51 -0400 Received: from mail-lf1-x136.google.com (mail-lf1-x136.google.com [IPv6:2a00:1450:4864:20::136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 70D667A992 for ; Thu, 17 Mar 2022 09:58:29 -0700 (PDT) Received: by mail-lf1-x136.google.com with SMTP id n19so10025073lfh.8 for ; Thu, 17 Mar 2022 09:58:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=eaxohQ9V+SbyCU6jPm+WVSzSaTbRz5JOX0s7z3i2z3I=; b=JecNR2A1WBJtpxnNqDnvZPdqrHpENKn8voZNOUOWI4Lcy8FSxZZUTuEMRFDnj1+b4B m9ptugbcEhPiwWEdHa2BzgWQO9w6RSEHaIaywPUgbwuM94fTeHI2DgfE1CEFVKNeVgk0 M/Fvoev8H7QohaD2qFbO1GPIeaDOfvtbBIwzU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=eaxohQ9V+SbyCU6jPm+WVSzSaTbRz5JOX0s7z3i2z3I=; b=Eo9Vd5uhPgPs09qUBzgy+JwJDjJFPMx/xlFeGgqJ3boZTpDG9jj92K8sjsln50DMZW dhUFRiVHDqZlZ5dSBO+lx+qWkJ7ZOSGKNMkcB96BrCeg4Id3qnCaisT74Olxhxy8H2Kw Kr3On0q9ytLFTkx/YT6P1Pyj1Q7e4dSBGUlzVw3zq4Id+9h4ZwIPWlYDfoexMFWEdX2c FpmWcPSqQddGsf/EUq/WHa1XZgW3MVllnVJi0cUVDHg4qAkA2UIs6NM7Cui/axZmIm2l LUKUp8bDkEHOK25qP+QVaGr7O768BE6XePeF8dbv4PnRGnWqRpXSurqa0B1uZN+Q+x3r OJ8g== X-Gm-Message-State: AOAM53225ZfOYluBfNnEDvxp/6jwOmq2P5BDizhRARIrH3d3v0+6KQtq kiy818AFqpBKMN+JvyuR/BAlfw== X-Google-Smtp-Source: ABdhPJwDio7Gf2p5JFZGUbZHlm+0h0m5k4CzujuHZw21dcd4a4YhY5gsL/eBRp2ROQ9sQcF9VpVO2w== X-Received: by 2002:a19:d61a:0:b0:43f:1a03:21ee with SMTP id n26-20020a19d61a000000b0043f1a0321eemr3624922lfg.152.1647536308145; Thu, 17 Mar 2022 09:58:28 -0700 (PDT) Received: from cloudflare.com ([2a01:110f:4809:d800::f9c]) by smtp.gmail.com with ESMTPSA id o11-20020ac2434b000000b004481eafa257sm488542lfl.285.2022.03.17.09.58.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Mar 2022 09:58:27 -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, Ilya Leoshkevich , Heiko Carstens , Vasily Gorbik Subject: [PATCH bpf-next 1/3] bpf: Treat bpf_sk_lookup remote_port as a 2-byte field Date: Thu, 17 Mar 2022 17:58:24 +0100 Message-Id: <20220317165826.1099418-2-jakub@cloudflare.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220317165826.1099418-1-jakub@cloudflare.com> References: <20220317165826.1099418-1-jakub@cloudflare.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net In commit 9a69e2b385f4 ("bpf: Make remote_port field in struct bpf_sk_lookup 16-bit wide") the remote_port field has been split up and re-declared from u32 to be16. However, the accompanying changes to the context access converter have not been well thought through when it comes big-endian platforms. Today 2-byte wide loads from offsetof(struct bpf_sk_lookup, remote_port) are handled as narrow loads from a 4-byte wide field. This by itself is not enough to create a problem, but when we combine 1. 32-bit wide access to ->remote_port backed by a 16-wide wide load, with 2. inherent difference between litte- and big-endian in how narrow loads need have to be handled (see bpf_ctx_narrow_access_offset), we get inconsistent results for a 2-byte loads from &ctx->remote_port on LE and BE architectures. This in turn makes BPF C code for the common case of 2-byte load from ctx->remote_port not portable. To rectify it, inform the context access converter that remote_port is 2-byte wide field, and only 1-byte loads need to be treated as narrow loads. At the same time, we special-case the 4-byte load from &ctx->remote_port to continue handling it the same way as do today, in order to keep the existing BPF programs working. Fixes: 9a69e2b385f4 ("bpf: Make remote_port field in struct bpf_sk_lookup 16-bit wide") Signed-off-by: Jakub Sitnicki --- net/core/filter.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/net/core/filter.c b/net/core/filter.c index 03655f2074ae..9b1e453baf6d 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -10989,13 +10989,24 @@ static bool sk_lookup_is_valid_access(int off, int size, case bpf_ctx_range(struct bpf_sk_lookup, local_ip4): case bpf_ctx_range_till(struct bpf_sk_lookup, remote_ip6[0], remote_ip6[3]): case bpf_ctx_range_till(struct bpf_sk_lookup, local_ip6[0], local_ip6[3]): - case offsetof(struct bpf_sk_lookup, remote_port) ... - offsetof(struct bpf_sk_lookup, local_ip4) - 1: case bpf_ctx_range(struct bpf_sk_lookup, local_port): case bpf_ctx_range(struct bpf_sk_lookup, ingress_ifindex): bpf_ctx_record_field_size(info, sizeof(__u32)); return bpf_ctx_narrow_access_ok(off, size, sizeof(__u32)); + case bpf_ctx_range(struct bpf_sk_lookup, remote_port): + /* Allow 4-byte access to 2-byte field for backward compatibility */ + if (size == sizeof(__u32)) + return off == offsetof(struct bpf_sk_lookup, remote_port); + bpf_ctx_record_field_size(info, sizeof(__be16)); + return bpf_ctx_narrow_access_ok(off, size, sizeof(__be16)); + + case offsetofend(struct bpf_sk_lookup, remote_port) ... + offsetof(struct bpf_sk_lookup, local_ip4) - 1: + /* Allow access to zero padding for backward compatibility */ + bpf_ctx_record_field_size(info, sizeof(__u16)); + return bpf_ctx_narrow_access_ok(off, size, sizeof(__u16)); + default: return false; } @@ -11077,6 +11088,11 @@ static u32 sk_lookup_convert_ctx_access(enum bpf_access_type type, sport, 2, target_size)); break; + case offsetofend(struct bpf_sk_lookup, remote_port): + *target_size = 2; + *insn++ = BPF_MOV32_IMM(si->dst_reg, 0); + break; + case offsetof(struct bpf_sk_lookup, local_port): *insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->src_reg, bpf_target_off(struct bpf_sk_lookup_kern, From patchwork Thu Mar 17 16:58:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jakub Sitnicki X-Patchwork-Id: 12784326 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 909ECC433F5 for ; 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Thu, 17 Mar 2022 09:58:28 -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, Ilya Leoshkevich , Heiko Carstens , Vasily Gorbik Subject: [PATCH bpf-next 2/3] selftests/bpf: Fix u8 narrow load checks for bpf_sk_lookup remote_port Date: Thu, 17 Mar 2022 17:58:25 +0100 Message-Id: <20220317165826.1099418-3-jakub@cloudflare.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220317165826.1099418-1-jakub@cloudflare.com> References: <20220317165826.1099418-1-jakub@cloudflare.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net In commit 9a69e2b385f4 ("bpf: Make remote_port field in struct bpf_sk_lookup 16-bit wide") ->remote_port field changed from __u32 to __be16. However, narrow load tests which exercise 1-byte sized loads from offsetof(struct bpf_sk_lookup, remote_port) were not adopted to reflect the change. As a result, on little-endian we continue testing loads from addresses: - (__u8 *)&ctx->remote_port + 3 - (__u8 *)&ctx->remote_port + 4 which map to the zero padding following the remote_port field, and don't break the tests because there is no observable change. While on big-endian, we observe breakage because tests expect to see zeros for values loaded from: - (__u8 *)&ctx->remote_port - 1 - (__u8 *)&ctx->remote_port - 2 Above addresses map to ->remote_ip6 field, which precedes ->remote_port, and are populated during the bpf_sk_lookup IPv6 tests. Unsurprisingly, on s390x we observe: #136/38 sk_lookup/narrow access to ctx v4:OK #136/39 sk_lookup/narrow access to ctx v6:FAIL Fix it by removing the checks for 1-byte loads from offsets outside of the ->remote_port field. Fixes: 9a69e2b385f4 ("bpf: Make remote_port field in struct bpf_sk_lookup 16-bit wide") Suggested-by: Ilya Leoshkevich Signed-off-by: Jakub Sitnicki --- tools/testing/selftests/bpf/progs/test_sk_lookup.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/test_sk_lookup.c b/tools/testing/selftests/bpf/progs/test_sk_lookup.c index bf5b7caefdd0..38b7a1fe67b6 100644 --- a/tools/testing/selftests/bpf/progs/test_sk_lookup.c +++ b/tools/testing/selftests/bpf/progs/test_sk_lookup.c @@ -413,8 +413,7 @@ int ctx_narrow_access(struct bpf_sk_lookup *ctx) /* Narrow loads from remote_port field. Expect SRC_PORT. */ if (LSB(ctx->remote_port, 0) != ((SRC_PORT >> 0) & 0xff) || - LSB(ctx->remote_port, 1) != ((SRC_PORT >> 8) & 0xff) || - LSB(ctx->remote_port, 2) != 0 || LSB(ctx->remote_port, 3) != 0) + LSB(ctx->remote_port, 1) != ((SRC_PORT >> 8) & 0xff)) return SK_DROP; if (LSW(ctx->remote_port, 0) != SRC_PORT) return SK_DROP; From patchwork Thu Mar 17 16:58:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jakub Sitnicki X-Patchwork-Id: 12784325 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6EA2DC433F5 for ; Thu, 17 Mar 2022 16:58:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236736AbiCQRAB (ORCPT ); Thu, 17 Mar 2022 13:00:01 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35744 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236722AbiCQQ74 (ORCPT ); Thu, 17 Mar 2022 12:59:56 -0400 Received: from mail-lj1-x230.google.com (mail-lj1-x230.google.com [IPv6:2a00:1450:4864:20::230]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CFC037B574 for ; Thu, 17 Mar 2022 09:58:32 -0700 (PDT) Received: by mail-lj1-x230.google.com with SMTP id r22so8065353ljd.4 for ; Thu, 17 Mar 2022 09:58:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=LwPiq0aOP34Qyg6rVQlymRAJ3+fiKOCehhtJ/fLH+0Q=; b=ZXwmYAJpocVs+zNgytE9eJ8NaB21z8nL/WSOwkErfEgHXBvCoCWK0Dcc15H8WiS3zj BnNbmECGbtSiJiwResAnkHdcKok/net5IBj7xhPpxs1GLlsE5NeSuWxonAGe8fo88A9E dXV+3dYN+QDYRNIwQl2bBTbeNqWW2LwMTXMN0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=LwPiq0aOP34Qyg6rVQlymRAJ3+fiKOCehhtJ/fLH+0Q=; b=zI6dG7ndsnsKXmHULUgNgf24IfJlnXM465umS+lxADX5h56LX6Z0NYWiw3AiaXZs2b 34raWHYp/eNEv+2ugBUPHOrlEXqMH57t29zTimpjvhF1ifclicTX/oSaVluL1t1d9g+r mRALIR0GKkJ14MKOZ63lCBbLoj5piYK5NQw4tO8LfNrU0B64FVdDg2h1KJa2lWsOEKjH 9ffY7Cwbwo+21O0eJb96SPaLzZdLH3SfffIySNpq+tWxrWgH1GxJoXV+ghCEOLoTHrRX r5xDYq+XIlSwyZ8lUXCNI5sIbwRBZU8yOAlfc1/DAcIi33dw8quQZWnEdilktc6dVb5X NfVQ== X-Gm-Message-State: AOAM532el6VPIbrGHUE9nWGnb0qgY1y4DUrZksZk1c0VopKxeGX8tSt1 70WeFYDOXD0yl6PV5oC7YWXPHB0dE3viqw== X-Google-Smtp-Source: ABdhPJxlHTxernOQ5RXtusjHurF794ZK8sfGX58mtDyrWHi3Tm1wvaargTP+OKZjCjsY0AcEWYPUPA== X-Received: by 2002:a05:651c:90a:b0:249:5d82:fe9c with SMTP id e10-20020a05651c090a00b002495d82fe9cmr3387251ljq.300.1647536310229; Thu, 17 Mar 2022 09:58:30 -0700 (PDT) Received: from cloudflare.com ([2a01:110f:4809:d800::f9c]) by smtp.gmail.com with ESMTPSA id j7-20020a2e3c07000000b00247fd2f7f46sm474083lja.47.2022.03.17.09.58.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Mar 2022 09:58:29 -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, Ilya Leoshkevich , Heiko Carstens , Vasily Gorbik Subject: [PATCH bpf-next 3/3] selftests/bpf: Fix test for 4-byte load from remote_port on big-endian Date: Thu, 17 Mar 2022 17:58:26 +0100 Message-Id: <20220317165826.1099418-4-jakub@cloudflare.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220317165826.1099418-1-jakub@cloudflare.com> References: <20220317165826.1099418-1-jakub@cloudflare.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net The context access converter rewrites the 4-byte load from bpf_sk_lookup->remote_port to a 2-byte load from bpf_sk_lookup_kern structure. It means that we cannot treat the destination register contents as a 32-bit value, or the code will not be portable across big- and little-endian architectures. This is exactly the same case as with 4-byte loads from bpf_sock->dst_port so follow the approach outlined in [1] and treat the register contents as a 16-bit value in the test. [1]: https://lore.kernel.org/bpf/20220317113920.1068535-5-jakub@cloudflare.com/ Fixes: 2ed0dc5937d3 ("selftests/bpf: Cover 4-byte load from remote_port in bpf_sk_lookup") Signed-off-by: Jakub Sitnicki --- tools/testing/selftests/bpf/progs/test_sk_lookup.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/progs/test_sk_lookup.c b/tools/testing/selftests/bpf/progs/test_sk_lookup.c index 38b7a1fe67b6..6058dcb11b36 100644 --- a/tools/testing/selftests/bpf/progs/test_sk_lookup.c +++ b/tools/testing/selftests/bpf/progs/test_sk_lookup.c @@ -418,9 +418,15 @@ int ctx_narrow_access(struct bpf_sk_lookup *ctx) if (LSW(ctx->remote_port, 0) != SRC_PORT) return SK_DROP; - /* Load from remote_port field with zero padding (backward compatibility) */ + /* + * NOTE: 4-byte load from bpf_sk_lookup at remote_port offset + * is quirky. It gets rewritten by the access converter to a + * 2-byte load for backward compatibility. Treating the load + * result as a be16 value makes the code portable across + * little- and big-endian platforms. + */ val_u32 = *(__u32 *)&ctx->remote_port; - if (val_u32 != bpf_htonl(bpf_ntohs(SRC_PORT) << 16)) + if (val_u32 != SRC_PORT) return SK_DROP; /* Narrow loads from local_port field. Expect DST_PORT. */