From patchwork Sat Feb 9 06:25:54 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin KaFai Lau X-Patchwork-Id: 1039119 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=fb.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=fb.com header.i=@fb.com header.b="Lahcc9qu"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 43xMYM4nZMz9sML for ; Sat, 9 Feb 2019 17:27:51 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726231AbfBIGZ6 (ORCPT ); Sat, 9 Feb 2019 01:25:58 -0500 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:47322 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726047AbfBIGZ6 (ORCPT ); Sat, 9 Feb 2019 01:25:58 -0500 Received: from pps.filterd (m0148461.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x196IrWx030656 for ; Fri, 8 Feb 2019 22:25:57 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-type; s=facebook; bh=SDSdbXdW1zHYLP648IDqqJI7WB0nfB4tih8elVfMlgI=; b=Lahcc9quju+Oj3KOoMVPFN7VlAG8wdF3KYbx3KUwqxi8pcCBr8df5AqfW0qvpwlucBvI jiGY4KogAue6AMEM0QqnrnC6WFSyC73Ac0ao//dWTQanuZ9dgJJdyuCX2HTK0vaq6yjs MbsTV50B2x4ptTzsYEiOvtJnnCNDkEYv0tE= Received: from mail.thefacebook.com ([199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2qhrey83rn-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT) for ; Fri, 08 Feb 2019 22:25:57 -0800 Received: from mx-out.facebook.com (2620:10d:c081:10::13) by mail.thefacebook.com (2620:10d:c081:35::125) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA) id 15.1.1531.3; Fri, 8 Feb 2019 22:25:56 -0800 Received: by devbig005.ftw2.facebook.com (Postfix, from userid 6611) id D01ED2943118; Fri, 8 Feb 2019 22:25:54 -0800 (PST) Smtp-Origin-Hostprefix: devbig From: Martin KaFai Lau Smtp-Origin-Hostname: devbig005.ftw2.facebook.com To: CC: Alexei Starovoitov , Daniel Borkmann , , Joe Stringer Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH bpf] bpf: Fix narrow load on a bpf_sock returned from sk_lookup() Date: Fri, 8 Feb 2019 22:25:54 -0800 Message-ID: <20190209062554.142612-1-kafai@fb.com> X-Mailer: git-send-email 2.17.1 X-FB-Internal: Safe MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-02-09_06:, , signatures=0 X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org By adding this test to test_verifier: { "reference tracking: access sk->src_ip4 (narrow load)", .insns = { BPF_SK_LOOKUP, BPF_MOV64_REG(BPF_REG_6, BPF_REG_0), BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 3), BPF_LDX_MEM(BPF_H, BPF_REG_2, BPF_REG_0, offsetof(struct bpf_sock, src_ip4) + 2), BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), BPF_EMIT_CALL(BPF_FUNC_sk_release), BPF_EXIT_INSN(), }, .prog_type = BPF_PROG_TYPE_SCHED_CLS, .result = ACCEPT, }, The above test loads 2 bytes from sk->src_ip4 where sk is obtained by bpf_sk_lookup_tcp(). It hits an internal verifier error from convert_ctx_accesses(): [root@arch-fb-vm1 bpf]# ./test_verifier 665 665 Failed to load prog 'Invalid argument'! 0: (b7) r2 = 0 1: (63) *(u32 *)(r10 -8) = r2 2: (7b) *(u64 *)(r10 -16) = r2 3: (7b) *(u64 *)(r10 -24) = r2 4: (7b) *(u64 *)(r10 -32) = r2 5: (7b) *(u64 *)(r10 -40) = r2 6: (7b) *(u64 *)(r10 -48) = r2 7: (bf) r2 = r10 8: (07) r2 += -48 9: (b7) r3 = 36 10: (b7) r4 = 0 11: (b7) r5 = 0 12: (85) call bpf_sk_lookup_tcp#84 13: (bf) r6 = r0 14: (15) if r0 == 0x0 goto pc+3 R0=sock(id=1,off=0,imm=0) R6=sock(id=1,off=0,imm=0) R10=fp0,call_-1 fp-8=????0000 fp-16=0000mmmm fp-24=mmmmmmmm fp-32=mmmmmmmm fp-40=mmmmmmmm fp-48=mmmmmmmm refs=1 15: (69) r2 = *(u16 *)(r0 +26) 16: (bf) r1 = r6 17: (85) call bpf_sk_release#86 18: (95) exit from 14 to 18: safe processed 20 insns (limit 131072), stack depth 48 bpf verifier is misconfigured Summary: 0 PASSED, 0 SKIPPED, 1 FAILED The bpf_sock_is_valid_access() is expecting src_ip4 can be narrowly loaded (meaning load any 1 or 2 bytes of the src_ip4) by marking info->ctx_field_size. However, this marked ctx_field_size is not used. This patch fixes it. Due to the recent refactoring in test_verifier, this new test will be added to the bpf-next branch (together with the bpf_tcp_sock patchset) to avoid merge conflict. Fixes: c64b7983288e ("bpf: Add PTR_TO_SOCKET verifier type") Cc: Joe Stringer Signed-off-by: Martin KaFai Lau Acked-by: Joe Stringer --- kernel/bpf/verifier.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 56674a7c3778..8f295b790297 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1617,12 +1617,13 @@ static int check_flow_keys_access(struct bpf_verifier_env *env, int off, return 0; } -static int check_sock_access(struct bpf_verifier_env *env, u32 regno, int off, - int size, enum bpf_access_type t) +static int check_sock_access(struct bpf_verifier_env *env, int insn_idx, + u32 regno, int off, int size, + enum bpf_access_type t) { struct bpf_reg_state *regs = cur_regs(env); struct bpf_reg_state *reg = ®s[regno]; - struct bpf_insn_access_aux info; + struct bpf_insn_access_aux info = {}; if (reg->smin_value < 0) { verbose(env, "R%d min value is negative, either use unsigned index or do a if (index >=0) check.\n", @@ -1636,6 +1637,8 @@ static int check_sock_access(struct bpf_verifier_env *env, u32 regno, int off, return -EACCES; } + env->insn_aux_data[insn_idx].ctx_field_size = info.ctx_field_size; + return 0; } @@ -2032,7 +2035,7 @@ static int check_mem_access(struct bpf_verifier_env *env, int insn_idx, u32 regn verbose(env, "cannot write into socket\n"); return -EACCES; } - err = check_sock_access(env, regno, off, size, t); + err = check_sock_access(env, insn_idx, regno, off, size, t); if (!err && value_regno >= 0) mark_reg_unknown(env, regs, value_regno); } else {