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=-15.8 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 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 C5D07C2D0E4 for ; Tue, 17 Nov 2020 23:35:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6316120B80 for ; Tue, 17 Nov 2020 23:35:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="WZyZegk3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727669AbgKQXfq (ORCPT ); Tue, 17 Nov 2020 18:35:46 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42316 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725779AbgKQXfq (ORCPT ); Tue, 17 Nov 2020 18:35:46 -0500 Received: from mail-lf1-x141.google.com (mail-lf1-x141.google.com [IPv6:2a00:1450:4864:20::141]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1F6EC0613CF for ; Tue, 17 Nov 2020 15:35:45 -0800 (PST) Received: by mail-lf1-x141.google.com with SMTP id 74so300073lfo.5 for ; Tue, 17 Nov 2020 15:35:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=BeKKFBADpWN954+IsjWIr6cgEypB+tWqmR313eWsUZQ=; b=WZyZegk3XS6jrNOhpP9XVbKY/k4lwQwrmxgAQthohq39GWVWjYSa37pMS8M9R+nA6q jN5lLGlDohciyA5mc2sqEmyPaVEcYzWvJhJnDfHaJtClBXNaqssKMNoQQM1to3AKnxHU o8G/h1a9oa7M3n8NtiEluAKT1GWyygLT0jhao= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=BeKKFBADpWN954+IsjWIr6cgEypB+tWqmR313eWsUZQ=; b=KNX69kOpfj88ALa94FkPd78FFIG9V65g1aUUftw92NMpzYaJuyPdr5zIIkRQtlIKXY /ZP3M/+xPLbqVJfKzW6GGJBmJ6wAFNFqHHLFUffxBfaTS05mncY0+P1ilg3x9RNOpGKn l82PMyjNc6lcNJ9FzyRqZUcckYDycxbTdxOhA428a9jhLF01uoFUJ/AeNAx1P6kLQF7G KOa4yqLsjavX6l7fQOpT3dgIrMA/5WLExCAEAxMGoHdtTlxNwnbFudeR8OtFSAlrDO4t gFMwqHOD5M3kDfK6+nPfYjhoYIn+fiyYi1CItdRDgvMZWfVXGqpNDUkCitBuNdFPZT4B vr7Q== X-Gm-Message-State: AOAM531ylXmVrIlGhpBn10dKzPwHD8lZQki5o821WAARMsJYWYc/WzMv eOaXOqerxk+qVNAWSHlxpCcteEzsHMjG1iYUJBybbw== X-Google-Smtp-Source: ABdhPJxYqW4KKC6wvgXSRVBXVMDStNeme+c99uG/OaKioLneRwupeJj+sC+B0/kqf9e+qh939D7483AjgJEoxO/41Jk= X-Received: by 2002:a19:418d:: with SMTP id o135mr2789233lfa.329.1605656144289; Tue, 17 Nov 2020 15:35:44 -0800 (PST) MIME-Version: 1.0 References: <20201117021307.1846300-1-kpsingh@chromium.org> In-Reply-To: From: KP Singh Date: Wed, 18 Nov 2020 00:35:33 +0100 Message-ID: Subject: Re: [PATCH bpf-next v3 1/2] bpf: Add bpf_lsm_set_bprm_opts helper To: Daniel Borkmann Cc: open list , bpf , Alexei Starovoitov , Florent Revest , Brendan Jackman , Pauline Middelink Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 17, 2020 at 11:41 PM Daniel Borkmann wrote: > > On 11/17/20 3:13 AM, KP Singh wrote: > > 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 | 18 ++++++++++++++++++ > > kernel/bpf/bpf_lsm.c | 27 +++++++++++++++++++++++++++ > > scripts/bpf_helpers_doc.py | 2 ++ > > tools/include/uapi/linux/bpf.h | 18 ++++++++++++++++++ > > 4 files changed, 65 insertions(+) > > > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > > index 162999b12790..bfa79054d106 100644 > > --- a/include/uapi/linux/bpf.h > > +++ b/include/uapi/linux/bpf.h > > @@ -3787,6 +3787,18 @@ union bpf_attr { > > * *ARG_PTR_TO_BTF_ID* of type *task_struct*. > > * Return > > * Pointer to the current task. > > + * > > + * long bpf_lsm_set_bprm_opts(struct linux_binprm *bprm, u64 flags) > > + * > > small nit: should have no extra newline (same for the tools/ copy) > > > + * Description > > + * Set or clear certain options on *bprm*: > > + * > > + * **BPF_LSM_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. > > + * > > */ > > #define __BPF_FUNC_MAPPER(FN) \ > > FN(unspec), \ > > @@ -3948,6 +3960,7 @@ 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 +4132,11 @@ 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..cd85482228a0 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 +52,30 @@ int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog, > > return 0; > > } > > > > +/* Mask for all the currently supported BPRM option flags */ > > +#define BPF_LSM_F_BRPM_OPTS_MASK BPF_LSM_F_BPRM_SECUREEXEC > > + > > +BPF_CALL_2(bpf_lsm_set_bprm_opts, struct linux_binprm *, bprm, u64, flags) > > +{ > > + > > ditto > > Would have fixed up these things on the fly while applying, but one small item > I wanted to bring up here given uapi which will then freeze: it would be cleaner > to call the helper just bpf_bprm_opts_set() or so given it's implied that we > attach to lsm here and we don't use _lsm in the naming for the others either. > Similarly, I'd drop the _LSM from the flag/mask. > Thanks Daniel, this makes sense and is more future proof, I respun this and sent out another version with some minor fixes and the rename. Also added Martin's acks. - KP