From patchwork Mon Nov 16 14:01:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: KP Singh X-Patchwork-Id: 11908593 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 X-Spam-Level: X-Spam-Status: No, score=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,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 4B0F6C5519F for ; Mon, 16 Nov 2020 14:01:45 +0000 (UTC) Received: from vger.kernel.org (unknown [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 045E5221F8 for ; Mon, 16 Nov 2020 14:01:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="KcVd0U8x" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 045E5221F8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=bpf-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730142AbgKPOBP (ORCPT ); Mon, 16 Nov 2020 09:01:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730138AbgKPOBO (ORCPT ); Mon, 16 Nov 2020 09:01:14 -0500 Received: from mail-wr1-x442.google.com (mail-wr1-x442.google.com [IPv6:2a00:1450:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 469EFC0613CF for ; Mon, 16 Nov 2020 06:01:14 -0800 (PST) Received: by mail-wr1-x442.google.com with SMTP id k2so18841313wrx.2 for ; Mon, 16 Nov 2020 06:01:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=NOdSjJjyvVNgQtsUvxPpLbV0pNCPERoLSo5YvFTvZ40=; b=KcVd0U8xlIfn7HK1Dq6WrEzt6gl1EKTomGeLKjsU4wabIIZWO2EFXxOSGWKPAK+03/ ViNO9GU9AWQzr0mUGQRGS2PcnK3ntavcvPIUtwlJCIZyHcAWrr5NrRZlyMWjH5iz0QFr PX6spB6WPtelclmUFnxwi5co4tpwztN53PQp0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=NOdSjJjyvVNgQtsUvxPpLbV0pNCPERoLSo5YvFTvZ40=; b=qqBiBLDRThBm/KX03zfWhpZE4OcSo+mtDAbE1bIUyH/LOmcH2j77RPoz1IN+jbFBiG IOCpa+lGZBdrBfo5ieCm2MvI3u/4LxPaO3AMmUQQHnOW+sxX2dOyh0i2dLryU5Cr4Uqh tD8jiB3eblyNyDuNVZVajZCFsjk03Zrj/gWMY5hX4U+ZnYPFurpsFOHJ/nlcscg/s3kG JmR2LWBJ+8M/zLKYacBKVmIFnEr/X2ipu8rmdhegqFb1ggRELD5Ny92VdUl8Yg2d0/Xh zRqCH8/aPq1C/Yw1RNrnHiUmEltZiHxvtY1t6jW685lR8dvp958lfNLtaIdfMNDMeZ8s zRFQ== X-Gm-Message-State: AOAM532sgmBFYup0L6LInJXeAR0rVmgAkXcSuxPINBRl0Yfa9EfbJycg nPTpLdKTzjU3dDZmgsFJGecI0Q== X-Google-Smtp-Source: ABdhPJxMHQb+3Y9GbxiERRhlbEo68i9w/ti694qVoyTC9Je04z9hGPFjfBRI4hwDyWJEAaSNgud49Q== X-Received: by 2002:a5d:5482:: with SMTP id h2mr8645344wrv.18.1605535272933; Mon, 16 Nov 2020 06:01:12 -0800 (PST) Received: from kpsingh.zrh.corp.google.com ([81.6.44.51]) by smtp.gmail.com with ESMTPSA id i11sm23172477wrm.1.2020.11.16.06.01.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Nov 2020 06:01:12 -0800 (PST) From: KP Singh To: linux-kernel@vger.kernel.org, bpf@vger.kernel.org Cc: Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Paul Turner , Pauline Middelink Subject: [PATCH bpf-next 1/2] bpf: Add bpf_lsm_set_bprm_opts helper Date: Mon, 16 Nov 2020 15:01:09 +0100 Message-Id: <20201116140110.1412642-1-kpsingh@chromium.org> X-Mailer: git-send-email 2.29.2.299.gdc1121823c-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: KP Singh The helper allows modification of certain bits on the linux_binprm struct starting with the secureexec bit which can be updated using the BPF_LSM_F_BPRM_SECUREEXEC flag. secureexec can be set by the LSM for privilege gaining executions to set the AT_SECURE auxv for glibc. When set, the dynamic linker disables the use of certain environment variables (like LD_PRELOAD). Signed-off-by: KP Singh --- include/uapi/linux/bpf.h | 14 ++++++++++++++ kernel/bpf/bpf_lsm.c | 20 ++++++++++++++++++++ scripts/bpf_helpers_doc.py | 2 ++ tools/include/uapi/linux/bpf.h | 14 ++++++++++++++ 4 files changed, 50 insertions(+) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 162999b12790..ed4f575be3d3 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3787,6 +3787,14 @@ union bpf_attr { * *ARG_PTR_TO_BTF_ID* of type *task_struct*. * Return * Pointer to the current task. + * + * void bpf_lsm_set_bprm_opts(struct linux_binprm *bprm, u64 flags) + * + * Description + * Sets certain options on the *bprm*: + * + * **BPF_LSM_F_BPRM_SECUREEXEC** Set the secureexec bit + * which sets the **AT_SECURE** auxv for glibc. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3948,6 +3956,7 @@ union bpf_attr { FN(task_storage_get), \ FN(task_storage_delete), \ FN(get_current_task_btf), \ + FN(lsm_set_bprm_opts), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper @@ -4119,6 +4128,11 @@ enum bpf_lwt_encap_mode { BPF_LWT_ENCAP_IP, }; +/* Flags for LSM helpers */ +enum { + BPF_LSM_F_BPRM_SECUREEXEC = (1ULL << 0), +}; + #define __bpf_md_ptr(type, name) \ union { \ type name; \ diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 553107f4706a..4d04fc490a14 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -7,6 +7,7 @@ #include #include #include +#include #include #include #include @@ -51,6 +52,23 @@ int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog, return 0; } +BPF_CALL_2(bpf_lsm_set_bprm_opts, struct linux_binprm *, bprm, u64, flags) +{ + bprm->secureexec = (flags & BPF_LSM_F_BPRM_SECUREEXEC); + return 0; +} + +BTF_ID_LIST_SINGLE(bpf_lsm_set_bprm_opts_btf_ids, struct, linux_binprm) + +const static struct bpf_func_proto bpf_lsm_set_bprm_opts_proto = { + .func = bpf_lsm_set_bprm_opts, + .gpl_only = false, + .ret_type = RET_VOID, + .arg1_type = ARG_PTR_TO_BTF_ID, + .arg1_btf_id = &bpf_lsm_set_bprm_opts_btf_ids[0], + .arg2_type = ARG_ANYTHING, +}; + static const struct bpf_func_proto * bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { @@ -71,6 +89,8 @@ bpf_lsm_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_task_storage_get_proto; case BPF_FUNC_task_storage_delete: return &bpf_task_storage_delete_proto; + case BPF_FUNC_lsm_set_bprm_opts: + return &bpf_lsm_set_bprm_opts_proto; default: return tracing_prog_func_proto(func_id, prog); } diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py index 31484377b8b1..c5bc947a70ad 100755 --- a/scripts/bpf_helpers_doc.py +++ b/scripts/bpf_helpers_doc.py @@ -418,6 +418,7 @@ class PrinterHelpers(Printer): 'struct bpf_tcp_sock', 'struct bpf_tunnel_key', 'struct bpf_xfrm_state', + 'struct linux_binprm', 'struct pt_regs', 'struct sk_reuseport_md', 'struct sockaddr', @@ -465,6 +466,7 @@ class PrinterHelpers(Printer): 'struct bpf_tcp_sock', 'struct bpf_tunnel_key', 'struct bpf_xfrm_state', + 'struct linux_binprm', 'struct pt_regs', 'struct sk_reuseport_md', 'struct sockaddr', diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 162999b12790..ed4f575be3d3 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3787,6 +3787,14 @@ union bpf_attr { * *ARG_PTR_TO_BTF_ID* of type *task_struct*. * Return * Pointer to the current task. + * + * void bpf_lsm_set_bprm_opts(struct linux_binprm *bprm, u64 flags) + * + * Description + * Sets certain options on the *bprm*: + * + * **BPF_LSM_F_BPRM_SECUREEXEC** Set the secureexec bit + * which sets the **AT_SECURE** auxv for glibc. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3948,6 +3956,7 @@ union bpf_attr { FN(task_storage_get), \ FN(task_storage_delete), \ FN(get_current_task_btf), \ + FN(lsm_set_bprm_opts), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper @@ -4119,6 +4128,11 @@ enum bpf_lwt_encap_mode { BPF_LWT_ENCAP_IP, }; +/* Flags for LSM helpers */ +enum { + BPF_LSM_F_BPRM_SECUREEXEC = (1ULL << 0), +}; + #define __bpf_md_ptr(type, name) \ union { \ type name; \