From patchwork Fri Sep 23 21:18:37 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Song Liu X-Patchwork-Id: 12987217 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 B6C66C04A95 for ; Fri, 23 Sep 2022 21:19:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230369AbiIWVTA convert rfc822-to-8bit (ORCPT ); Fri, 23 Sep 2022 17:19:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39572 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229495AbiIWVS7 (ORCPT ); Fri, 23 Sep 2022 17:18:59 -0400 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8954E12206D for ; Fri, 23 Sep 2022 14:18:58 -0700 (PDT) Received: from pps.filterd (m0109334.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 28NIGBGR017004 for ; Fri, 23 Sep 2022 14:18:58 -0700 Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3jsb1pvek8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 23 Sep 2022 14:18:58 -0700 Received: from twshared20273.14.frc2.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::c) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 23 Sep 2022 14:18:56 -0700 Received: by devbig932.frc1.facebook.com (Postfix, from userid 4523) id 2E269D4BF9A6; Fri, 23 Sep 2022 14:18:51 -0700 (PDT) From: Song Liu To: CC: , , , , , , , Song Liu Subject: [PATCH bpf-next 2/2] bpf: Enforce W^X for bpf trampoline Date: Fri, 23 Sep 2022 14:18:37 -0700 Message-ID: <20220923211837.3044723-3-song@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220923211837.3044723-1-song@kernel.org> References: <20220923211837.3044723-1-song@kernel.org> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-GUID: yV47i2gmz2_BZ3Gt8UAJn2FWxVbhcurk X-Proofpoint-ORIG-GUID: yV47i2gmz2_BZ3Gt8UAJn2FWxVbhcurk X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.528,FMLib:17.11.122.1 definitions=2022-09-23_10,2022-09-22_02,2022-06-22_01 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Mark the trampoline as RO+X after arch_prepare_bpf_trampoline, so that the trampoine follows W^X rule strictly. This will turn off warnings like CPA refuse W^X violation: 8000000000000163 -> 0000000000000163 range: ... Also remove bpf_jit_alloc_exec_page(), since it is not used any more. Signed-off-by: Song Liu --- include/linux/bpf.h | 1 - kernel/bpf/trampoline.c | 22 +++++----------------- 2 files changed, 5 insertions(+), 18 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index a8d0cfe14372..44a3d6b3c924 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1008,7 +1008,6 @@ int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, int num_funcs); void bpf_dispatcher_change_prog(struct bpf_dispatcher *d, struct bpf_prog *from, struct bpf_prog *to); /* Called only from JIT-enabled code, so there's no need for stubs. */ -void *bpf_jit_alloc_exec_page(void); void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym); void bpf_image_ksym_del(struct bpf_ksym *ksym); void bpf_ksym_add(struct bpf_ksym *ksym); diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 41b67eb83ab3..6f7b939321d6 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -116,22 +116,6 @@ bool bpf_prog_has_trampoline(const struct bpf_prog *prog) (ptype == BPF_PROG_TYPE_LSM && eatype == BPF_LSM_MAC); } -void *bpf_jit_alloc_exec_page(void) -{ - void *image; - - image = bpf_jit_alloc_exec(PAGE_SIZE); - if (!image) - return NULL; - - set_vm_flush_reset_perms(image); - /* Keep image as writeable. The alternative is to keep flipping ro/rw - * every time new program is attached or detached. - */ - set_memory_x((long)image, 1); - return image; -} - void bpf_image_ksym_add(void *data, struct bpf_ksym *ksym) { ksym->start = (unsigned long) data; @@ -404,9 +388,10 @@ static struct bpf_tramp_image *bpf_tramp_image_alloc(u64 key, u32 idx) goto out_free_im; err = -ENOMEM; - im->image = image = bpf_jit_alloc_exec_page(); + im->image = image = bpf_jit_alloc_exec(PAGE_SIZE); if (!image) goto out_uncharge; + set_vm_flush_reset_perms(image); err = percpu_ref_init(&im->pcref, __bpf_tramp_image_release, 0, GFP_KERNEL); if (err) @@ -483,6 +468,9 @@ static int bpf_trampoline_update(struct bpf_trampoline *tr, bool lock_direct_mut if (err < 0) goto out; + set_memory_ro((long)im->image, 1); + set_memory_x((long)im->image, 1); + WARN_ON(tr->cur_image && tr->selector == 0); WARN_ON(!tr->cur_image && tr->selector); if (tr->cur_image)