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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 5A970C2D0E4 for ; Tue, 17 Nov 2020 23:29:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E78C0222E9 for ; Tue, 17 Nov 2020 23:29:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="l5TmlNBF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726306AbgKQX3d (ORCPT ); Tue, 17 Nov 2020 18:29:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41344 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725747AbgKQX3d (ORCPT ); Tue, 17 Nov 2020 18:29:33 -0500 Received: from mail-wm1-x344.google.com (mail-wm1-x344.google.com [IPv6:2a00:1450:4864:20::344]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE7A7C0613CF for ; Tue, 17 Nov 2020 15:29:32 -0800 (PST) Received: by mail-wm1-x344.google.com with SMTP id 1so416428wme.3 for ; Tue, 17 Nov 2020 15:29:32 -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=GlGLdU3rd5bCgeYAdwEbTNrseBnDwGqmsLX/kx+4ztU=; b=l5TmlNBF02C508yahqVzzJu2xsij69rRfVf2qWik3okKS2tJAgFzBfe6w/C+qNcS3W YZc/gQhFziRnRC2PACisFj5Sm2l2hnm4ETf57wZ7900v5Tcf5dksa9XONy1Bkjpw7l6q 4pwcLWiZzya+0cfxH42hXBvjaAXyKSckYpP7g= 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=GlGLdU3rd5bCgeYAdwEbTNrseBnDwGqmsLX/kx+4ztU=; b=t+IeUdO6OjkE2LpiWTHrD6GSgxkzTJ+6mnlsmOh9b3ZZ9Me+CZSRO+8qSj2kS4S/QL cfIfu264RBmrJW13kpW6T5zlpSe6GbXpbiGdz6dsy1wp6YSUnJXyotMYkbnzCoapP/Bu /H/jkYMtisimbatsSVDcRPNl/10G+g0gUS4fguSSZbTZIMxyMVT5+IozmhDxjN5/eazN T7xCx5sXZ1FzORCFA3V/pr14yf8gMGFPxrFLRk3K+DMVhVO+sYaqF47ZYfoPeghVM4m0 +cxJYqFkDkl2pWOVXxtezyv9KItYlEm8bzdt192dfbzKuKUum6rFmgrn/R4WmaOaMRd8 uvtg== X-Gm-Message-State: AOAM5315Uevgc76DO47XCrlsC8c4aFNlgBE47eyvQdi0vsHo37Z028sx cK4GuWRUF49i8P1lJLDUtiKXXQ== X-Google-Smtp-Source: ABdhPJznFa5U6v0MtEpALP5uFBcZyFe4ubh6gG66TwACrqbQvTqcVQLSXITdUZbfHH7kAdzMio6b9w== X-Received: by 2002:a1c:4d03:: with SMTP id o3mr1410139wmh.150.1605655771321; Tue, 17 Nov 2020 15:29:31 -0800 (PST) Received: from kpsingh.c.googlers.com.com (203.75.199.104.bc.googleusercontent.com. [104.199.75.203]) by smtp.gmail.com with ESMTPSA id k3sm10212083wrn.81.2020.11.17.15.29.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 17 Nov 2020 15:29:30 -0800 (PST) From: KP Singh To: linux-kernel@vger.kernel.org, bpf@vger.kernel.org Cc: Martin KaFai Lau , Alexei Starovoitov , Daniel Borkmann , Florent Revest , Brendan Jackman , Pauline Middelink Subject: [PATCH bpf-next v4 1/2] bpf: Add bpf_bprm_opts_set helper Date: Tue, 17 Nov 2020 23:29:28 +0000 Message-Id: <20201117232929.2156341-1-kpsingh@chromium.org> X-Mailer: git-send-email 2.29.2.299.gdc1121823c-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org 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_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). Acked-by: Martin KaFai Lau Signed-off-by: KP Singh --- include/uapi/linux/bpf.h | 16 ++++++++++++++++ kernel/bpf/bpf_lsm.c | 26 ++++++++++++++++++++++++++ scripts/bpf_helpers_doc.py | 2 ++ tools/include/uapi/linux/bpf.h | 16 ++++++++++++++++ 4 files changed, 60 insertions(+) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 162999b12790..a52299b80b9d 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3787,6 +3787,16 @@ union bpf_attr { * *ARG_PTR_TO_BTF_ID* of type *task_struct*. * Return * Pointer to the current task. + * + * long bpf_bprm_opts_set(struct linux_binprm *bprm, u64 flags) + * Description + * Set or clear certain options on *bprm*: + * + * **BPF_F_BPRM_SECUREEXEC** Set the secureexec bit + * which sets the **AT_SECURE** auxv for glibc. The bit + * is cleared if the flag is not specified. + * Return + * **-EINVAL** if invalid *flags* are passed, zero otherwise. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3948,6 +3958,7 @@ union bpf_attr { FN(task_storage_get), \ FN(task_storage_delete), \ FN(get_current_task_btf), \ + FN(bprm_opts_set), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper @@ -4119,6 +4130,11 @@ enum bpf_lwt_encap_mode { BPF_LWT_ENCAP_IP, }; +/* Flags for bpf_bprm_opts_set helper */ +enum { + BPF_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..b4f27a874092 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 +52,29 @@ int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog, return 0; } +/* Mask for all the currently supported BPRM option flags */ +#define BPF_F_BRPM_OPTS_MASK BPF_F_BPRM_SECUREEXEC + +BPF_CALL_2(bpf_bprm_opts_set, struct linux_binprm *, bprm, u64, flags) +{ + if (flags & ~BPF_F_BRPM_OPTS_MASK) + return -EINVAL; + + bprm->secureexec = (flags & BPF_F_BPRM_SECUREEXEC); + return 0; +} + +BTF_ID_LIST_SINGLE(bpf_bprm_opts_set_btf_ids, struct, linux_binprm) + +const static struct bpf_func_proto bpf_bprm_opts_set_proto = { + .func = bpf_bprm_opts_set, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_BTF_ID, + .arg1_btf_id = &bpf_bprm_opts_set_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 +95,8 @@ 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_bprm_opts_set: + return &bpf_bprm_opts_set_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..a52299b80b9d 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3787,6 +3787,16 @@ union bpf_attr { * *ARG_PTR_TO_BTF_ID* of type *task_struct*. * Return * Pointer to the current task. + * + * long bpf_bprm_opts_set(struct linux_binprm *bprm, u64 flags) + * Description + * Set or clear certain options on *bprm*: + * + * **BPF_F_BPRM_SECUREEXEC** Set the secureexec bit + * which sets the **AT_SECURE** auxv for glibc. The bit + * is cleared if the flag is not specified. + * Return + * **-EINVAL** if invalid *flags* are passed, zero otherwise. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3948,6 +3958,7 @@ union bpf_attr { FN(task_storage_get), \ FN(task_storage_delete), \ FN(get_current_task_btf), \ + FN(bprm_opts_set), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper @@ -4119,6 +4130,11 @@ enum bpf_lwt_encap_mode { BPF_LWT_ENCAP_IP, }; +/* Flags for bpf_bprm_opts_set helper */ +enum { + BPF_F_BPRM_SECUREEXEC = (1ULL << 0), +}; + #define __bpf_md_ptr(type, name) \ union { \ type name; \ -- 2.29.2.299.gdc1121823c-goog