From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AEBAFC282C7 for ; Tue, 29 Jan 2019 11:59:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7479720880 for ; Tue, 29 Jan 2019 11:59:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548763171; bh=D8+vrBRfDnI0U144nd3c0v1zHHmv2wMBoAtlxPFtbvc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=mdA3nQxf+P4YpYdqipPHb0G4FER4/ezPhK7lxhxtjQ/7X27wpSc5nL3vyuJ/a189D anUKxThO2N85jlwodp831OzQ/S+1XHnzE5m40xtpofSyMmAlxGCS5arZf9mWijS+gP 5g8Y3jyS8zDq9J2CRRnyfSjHRbu1BM6vi1Mdu8zk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731333AbfA2L7a (ORCPT ); Tue, 29 Jan 2019 06:59:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:37776 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731128AbfA2LrH (ORCPT ); Tue, 29 Jan 2019 06:47:07 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8ACD0214DA; Tue, 29 Jan 2019 11:47:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1548762426; bh=D8+vrBRfDnI0U144nd3c0v1zHHmv2wMBoAtlxPFtbvc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=UiixRWaLQRMRuQUTYnEwI0LUanSX6wDhrP3wpnTyHWdEJ6ywKVgfX1MmNjbMrlBXP MfYNqy+4m7PPJZ8MoYJ9oHprBdD+8WNzS2W/ISHDEqXcvNCunYdbEw17yAGHt467xk mPMphxNaqzTfQFH85I2e8xA4MAZ4YJTKsEkpkJ+U= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Borkmann , Martin KaFai Lau , Alexei Starovoitov , Sasha Levin Subject: [PATCH 4.19 097/103] bpf: fix inner map masking to prevent oob under speculation Date: Tue, 29 Jan 2019 12:36:14 +0100 Message-Id: <20190129113207.316787879@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190129113159.567154026@linuxfoundation.org> References: <20190129113159.567154026@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ [ commit 9d5564ddcf2a0f5ba3fa1c3a1f8a1b59ad309553 upstream ] During review I noticed that inner meta map setup for map in map is buggy in that it does not propagate all needed data from the reference map which the verifier is later accessing. In particular one such case is index masking to prevent out of bounds access under speculative execution due to missing the map's unpriv_array/index_mask field propagation. Fix this such that the verifier is generating the correct code for inlined lookups in case of unpriviledged use. Before patch (test_verifier's 'map in map access' dump): # bpftool prog dump xla id 3 0: (62) *(u32 *)(r10 -4) = 0 1: (bf) r2 = r10 2: (07) r2 += -4 3: (18) r1 = map[id:4] 5: (07) r1 += 272 | 6: (61) r0 = *(u32 *)(r2 +0) | 7: (35) if r0 >= 0x1 goto pc+6 | Inlined map in map lookup 8: (54) (u32) r0 &= (u32) 0 | with index masking for 9: (67) r0 <<= 3 | map->unpriv_array. 10: (0f) r0 += r1 | 11: (79) r0 = *(u64 *)(r0 +0) | 12: (15) if r0 == 0x0 goto pc+1 | 13: (05) goto pc+1 | 14: (b7) r0 = 0 | 15: (15) if r0 == 0x0 goto pc+11 16: (62) *(u32 *)(r10 -4) = 0 17: (bf) r2 = r10 18: (07) r2 += -4 19: (bf) r1 = r0 20: (07) r1 += 272 | 21: (61) r0 = *(u32 *)(r2 +0) | Index masking missing (!) 22: (35) if r0 >= 0x1 goto pc+3 | for inner map despite 23: (67) r0 <<= 3 | map->unpriv_array set. 24: (0f) r0 += r1 | 25: (05) goto pc+1 | 26: (b7) r0 = 0 | 27: (b7) r0 = 0 28: (95) exit After patch: # bpftool prog dump xla id 1 0: (62) *(u32 *)(r10 -4) = 0 1: (bf) r2 = r10 2: (07) r2 += -4 3: (18) r1 = map[id:2] 5: (07) r1 += 272 | 6: (61) r0 = *(u32 *)(r2 +0) | 7: (35) if r0 >= 0x1 goto pc+6 | Same inlined map in map lookup 8: (54) (u32) r0 &= (u32) 0 | with index masking due to 9: (67) r0 <<= 3 | map->unpriv_array. 10: (0f) r0 += r1 | 11: (79) r0 = *(u64 *)(r0 +0) | 12: (15) if r0 == 0x0 goto pc+1 | 13: (05) goto pc+1 | 14: (b7) r0 = 0 | 15: (15) if r0 == 0x0 goto pc+12 16: (62) *(u32 *)(r10 -4) = 0 17: (bf) r2 = r10 18: (07) r2 += -4 19: (bf) r1 = r0 20: (07) r1 += 272 | 21: (61) r0 = *(u32 *)(r2 +0) | 22: (35) if r0 >= 0x1 goto pc+4 | Now fixed inlined inner map 23: (54) (u32) r0 &= (u32) 0 | lookup with proper index masking 24: (67) r0 <<= 3 | for map->unpriv_array. 25: (0f) r0 += r1 | 26: (05) goto pc+1 | 27: (b7) r0 = 0 | 28: (b7) r0 = 0 29: (95) exit Fixes: b2157399cc98 ("bpf: prevent out-of-bounds speculation") Signed-off-by: Daniel Borkmann Acked-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Signed-off-by: Sasha Levin --- kernel/bpf/map_in_map.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) --- a/kernel/bpf/map_in_map.c +++ b/kernel/bpf/map_in_map.c @@ -12,6 +12,7 @@ struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd) { struct bpf_map *inner_map, *inner_map_meta; + u32 inner_map_meta_size; struct fd f; f = fdget(inner_map_ufd); @@ -35,7 +36,12 @@ struct bpf_map *bpf_map_meta_alloc(int i return ERR_PTR(-EINVAL); } - inner_map_meta = kzalloc(sizeof(*inner_map_meta), GFP_USER); + inner_map_meta_size = sizeof(*inner_map_meta); + /* In some cases verifier needs to access beyond just base map. */ + if (inner_map->ops == &array_map_ops) + inner_map_meta_size = sizeof(struct bpf_array); + + inner_map_meta = kzalloc(inner_map_meta_size, GFP_USER); if (!inner_map_meta) { fdput(f); return ERR_PTR(-ENOMEM); @@ -45,9 +51,16 @@ struct bpf_map *bpf_map_meta_alloc(int i inner_map_meta->key_size = inner_map->key_size; inner_map_meta->value_size = inner_map->value_size; inner_map_meta->map_flags = inner_map->map_flags; - inner_map_meta->ops = inner_map->ops; inner_map_meta->max_entries = inner_map->max_entries; + /* Misc members not needed in bpf_map_meta_equal() check. */ + inner_map_meta->ops = inner_map->ops; + if (inner_map->ops == &array_map_ops) { + inner_map_meta->unpriv_array = inner_map->unpriv_array; + container_of(inner_map_meta, struct bpf_array, map)->index_mask = + container_of(inner_map, struct bpf_array, map)->index_mask; + } + fdput(f); return inner_map_meta; }