From patchwork Thu Mar 14 19:46:17 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bethany Jamison X-Patchwork-Id: 1912224 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@legolas.ozlabs.org Authentication-Results: legolas.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ubuntu.com (client-ip=185.125.189.65; helo=lists.ubuntu.com; envelope-from=kernel-team-bounces@lists.ubuntu.com; receiver=patchwork.ozlabs.org) Received: from lists.ubuntu.com (lists.ubuntu.com [185.125.189.65]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by legolas.ozlabs.org (Postfix) with ESMTPS id 4TwdDl1b8nz1yWn for ; Fri, 15 Mar 2024 06:46:47 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=lists.ubuntu.com) by lists.ubuntu.com with esmtp (Exim 4.86_2) (envelope-from ) id 1rkr27-0007Dr-CQ; Thu, 14 Mar 2024 19:46:31 +0000 Received: from smtp-relay-internal-0.internal ([10.131.114.225] helo=smtp-relay-internal-0.canonical.com) by lists.ubuntu.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.86_2) (envelope-from ) id 1rkr1x-0007C0-Ry for kernel-team@lists.ubuntu.com; Thu, 14 Mar 2024 19:46:21 +0000 Received: from mail-io1-f71.google.com (mail-io1-f71.google.com [209.85.166.71]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-internal-0.canonical.com (Postfix) with ESMTPS id ADBE03F280 for ; Thu, 14 Mar 2024 19:46:21 +0000 (UTC) Received: by mail-io1-f71.google.com with SMTP id ca18e2360f4ac-7c8a7d77806so100983939f.0 for ; Thu, 14 Mar 2024 12:46:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1710445580; x=1711050380; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=MlkBjGTpM2rosc4WEuymBcHrEGILTbaGExV29nwoIS8=; b=v5bI/96H30ZZfQZbmP8aFoMpe5XVGPmAT9EgKFOuyUnyALHWkevnbofoOD1AxMjVCa SiMKiLa3+S6a4XQpFBr3w0pmaoRVw1C5k1qCRnmCU8MF8/VAnrkG++XFwv7UEgVPVhK7 O3zfxqBMRFdkV2OVynHDjwyCRmy74Bbx+ytycYJ/t0H1yvmG7CWfIxZyL+c+OopBVyMZ Br4p7TofjC0SWrVUw9neNtyerh6QdsfMR+J26rrGh57K4ATbshHENMS8l5iPaav2XvAX 71tUB4QDOODmcpm+qmOkRG89H5fExwziyztVbUcv7GYV58MBqxb0nTLpOdPAmI9ykjdS DDXA== X-Gm-Message-State: AOJu0YwjmtTtTRYbukFF5oWibb8C3P1CQyAkFFzG4/nleYgLWM/NuhzN 7rdZVfLUPwoa+U/XA7J3iIgIg7ZiC7tko3PlyBNOlxHAq0DYD4ALPrM0A2e6qHgGz7gnTeknqjQ vkHJ/Eh6HkdDaQBY5xUvhElHpzgzZ/WupBcbC3pcQbHerbs1AGwW6t2iB9L5BJkYUJY01oPFLXo hSf0Pt8uYkOg== X-Received: by 2002:a05:6602:1d81:b0:7c8:dc82:45fc with SMTP id hj1-20020a0566021d8100b007c8dc8245fcmr1411736iob.17.1710445580110; Thu, 14 Mar 2024 12:46:20 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFBnj1nI/UEh0lxxqa9A3x4PyEHoKb7l0wdMn4Id5W1Dj/yCr+z5YLiNlIy97mmDXvwM7Ws+w== X-Received: by 2002:a05:6602:1d81:b0:7c8:dc82:45fc with SMTP id hj1-20020a0566021d8100b007c8dc8245fcmr1411722iob.17.1710445579783; Thu, 14 Mar 2024 12:46:19 -0700 (PDT) Received: from smtp.gmail.com (104-218-69-129.dynamic.lnk.ne.allofiber.net. [104.218.69.129]) by smtp.gmail.com with ESMTPSA id g64-20020a028546000000b0047726b17979sm325561jai.50.2024.03.14.12.46.19 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 14 Mar 2024 12:46:19 -0700 (PDT) From: Bethany Jamison To: kernel-team@lists.ubuntu.com Subject: [SRU][F][PATCH 1/1] bpf: Reject variable offset alu on PTR_TO_FLOW_KEYS Date: Thu, 14 Mar 2024 14:46:17 -0500 Message-Id: <20240314194617.42266-3-bethany.jamison@canonical.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240314194617.42266-1-bethany.jamison@canonical.com> References: <20240314194617.42266-1-bethany.jamison@canonical.com> MIME-Version: 1.0 X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.20 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: "kernel-team" From: Hao Sun For PTR_TO_FLOW_KEYS, check_flow_keys_access() only uses fixed off for validation. However, variable offset ptr alu is not prohibited for this ptr kind. So the variable offset is not checked. The following prog is accepted: func#0 @0 0: R1=ctx() R10=fp0 0: (bf) r6 = r1 ; R1=ctx() R6_w=ctx() 1: (79) r7 = *(u64 *)(r6 +144) ; R6_w=ctx() R7_w=flow_keys() 2: (b7) r8 = 1024 ; R8_w=1024 3: (37) r8 /= 1 ; R8_w=scalar() 4: (57) r8 &= 1024 ; R8_w=scalar(smin=smin32=0, smax=umax=smax32=umax32=1024,var_off=(0x0; 0x400)) 5: (0f) r7 += r8 mark_precise: frame0: last_idx 5 first_idx 0 subseq_idx -1 mark_precise: frame0: regs=r8 stack= before 4: (57) r8 &= 1024 mark_precise: frame0: regs=r8 stack= before 3: (37) r8 /= 1 mark_precise: frame0: regs=r8 stack= before 2: (b7) r8 = 1024 6: R7_w=flow_keys(smin=smin32=0,smax=umax=smax32=umax32=1024,var_off =(0x0; 0x400)) R8_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=1024, var_off=(0x0; 0x400)) 6: (79) r0 = *(u64 *)(r7 +0) ; R0_w=scalar() 7: (95) exit This prog loads flow_keys to r7, and adds the variable offset r8 to r7, and finally causes out-of-bounds access: BUG: unable to handle page fault for address: ffffc90014c80038 [...] Call Trace: bpf_dispatcher_nop_func include/linux/bpf.h:1231 [inline] __bpf_prog_run include/linux/filter.h:651 [inline] bpf_prog_run include/linux/filter.h:658 [inline] bpf_prog_run_pin_on_cpu include/linux/filter.h:675 [inline] bpf_flow_dissect+0x15f/0x350 net/core/flow_dissector.c:991 bpf_prog_test_run_flow_dissector+0x39d/0x620 net/bpf/test_run.c:1359 bpf_prog_test_run kernel/bpf/syscall.c:4107 [inline] __sys_bpf+0xf8f/0x4560 kernel/bpf/syscall.c:5475 __do_sys_bpf kernel/bpf/syscall.c:5561 [inline] __se_sys_bpf kernel/bpf/syscall.c:5559 [inline] __x64_sys_bpf+0x73/0xb0 kernel/bpf/syscall.c:5559 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0x3f/0x110 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b Fix this by rejecting ptr alu with variable offset on flow_keys. Applying the patch rejects the program with "R7 pointer arithmetic on flow_keys prohibited". Fixes: d58e468b1112 ("flow_dissector: implements flow dissector BPF hook") Signed-off-by: Hao Sun Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20240115082028.9992-1-sunhao.th@gmail.com (backported from commit 22c7fa171a02d310e3a3f6ed46a698ca8a0060ed) [bjamison: upstream moved a case in 'switch (ptr_reg->type)' to an if-block before the switch block, this creates a context conflict for Focal when applying the fix commit but is logically the same, I kept the conflicting case in the switch block and added the fix commit changes as given] CVE-2024-26589 Signed-off-by: Bethany Jamison --- kernel/bpf/verifier.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index e132c18f03e23..5a375e28bfeaf 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -4664,6 +4664,10 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, verbose(env, "R%d pointer arithmetic on %s prohibited, null-check it first\n", dst, reg_type_str[ptr_reg->type]); return -EACCES; + case PTR_TO_FLOW_KEYS: + if (known) + break; + fallthrough; case CONST_PTR_TO_MAP: /* smin_val represents the known value */ if (known && smin_val == 0 && opcode == BPF_ADD)