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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B5D6FC433EF for ; Wed, 1 Jun 2022 20:54:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230285AbiFAUyQ (ORCPT ); Wed, 1 Jun 2022 16:54:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33544 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229482AbiFAUyN (ORCPT ); Wed, 1 Jun 2022 16:54:13 -0400 Received: from mail-pj1-x104a.google.com (mail-pj1-x104a.google.com [IPv6:2607:f8b0:4864:20::104a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 538CC217614 for ; Wed, 1 Jun 2022 13:54:03 -0700 (PDT) Received: by mail-pj1-x104a.google.com with SMTP id z16-20020a17090a015000b001dbc8da29a1so1542091pje.7 for ; Wed, 01 Jun 2022 13:54:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=sOqyOc0RV6TEgXr+bTqTDYTCAUIFhqEy6NBax/+Wu4M=; b=KU/UBWFiNSw1xK3zhUj/mu+Sw97S5oYLcVxHB0vrW+tHOLlXTwlAPFq6vOaBcXokAR 5mZ6mhsjGn7tmPRPQl6XXJxuFER/fIjJPRKReyerSnhIw6yEv4GfkraPv2lhHBpRS9+K Kf/5ch7ask0l7Vq8pIYtypF5/dbKXKQlIwjOS+vMhiIeaMWVwuRMryg5djXy8pPzIE7O ZurK2DIfjaHixJxLVN7J6zOVA/nyeGWYH5O4n07ev6MOJVfSQ1pQALIhuuSWUrJs+E9K rhIB0oHYJjt76zpqsgcWWGSOQ6+aWJbPDKVyJU8uii+7I1WddCPGh3cFAtHlUuDOY6BQ JxEA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=sOqyOc0RV6TEgXr+bTqTDYTCAUIFhqEy6NBax/+Wu4M=; b=p+C9OzNeigbDP9VkgmIt1pc6nSmqAyYkDosnEagmsjOyu8TWieehby+QsKrM/EZQH9 utm/8R4UeXe61eZHdaXFZ+lFxAJMYzR91TFqZEVHiN9YF9QE4eZZSKNtfOooo+YrRJjp RfuWrYEwefjF52yOiHdX8vQct7mDtFJhxNfwZi1kJ/jSyL4DtZgK4E+ohmxsA9igVDlH RzxIKvx698RMqgL6s4I7QChu97DG/GkBh+fY8ZrdTBJFrpN4uPf5fQw94AnlUVSoyWeS yTlqt3VEqur0u3GpxZxtfSp8EtDRz8Xjq7dkdZRftI2A/iICmgzpFCw0qFg+Oy/tNfYs U/PA== X-Gm-Message-State: AOAM531XXGxN587ZrPI0Ro2rXdCWBaJHHIiRlYqwrU7hxApFQhjLz1+y dv9R8XV6hJvdrcPqANRvv9jXz20= X-Google-Smtp-Source: ABdhPJxwkEk9yUDmAjCIG1NiTs1oDU04xt3JbFOSxkgPFy34ArqAEjPI9OzLCENagAjelN1XWFuFbKA= X-Received: from sdf.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5935]) (user=sdf job=sendgmr) by 2002:a05:6a00:4008:b0:518:cc07:d1f8 with SMTP id by8-20020a056a00400800b00518cc07d1f8mr42089742pfb.8.1654110150604; Wed, 01 Jun 2022 12:02:30 -0700 (PDT) Date: Wed, 1 Jun 2022 12:02:13 -0700 In-Reply-To: <20220601190218.2494963-1-sdf@google.com> Message-Id: <20220601190218.2494963-7-sdf@google.com> Mime-Version: 1.0 References: <20220601190218.2494963-1-sdf@google.com> X-Mailer: git-send-email 2.36.1.255.ge46751e96f-goog Subject: [PATCH bpf-next v8 06/11] bpf: allow writing to a subset of sock fields from lsm progtype From: Stanislav Fomichev To: netdev@vger.kernel.org, bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, Stanislav Fomichev Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org For now, allow only the obvious ones, like sk_priority and sk_mark. Signed-off-by: Stanislav Fomichev --- kernel/bpf/bpf_lsm.c | 58 +++++++++++++++++++++++++++++++++++++++++++ kernel/bpf/verifier.c | 3 ++- 2 files changed, 60 insertions(+), 1 deletion(-) diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index 83aa431dd52e..feba8e96f58d 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -303,7 +303,65 @@ bool bpf_lsm_is_sleepable_hook(u32 btf_id) const struct bpf_prog_ops lsm_prog_ops = { }; +static int lsm_btf_struct_access(struct bpf_verifier_log *log, + const struct btf *btf, + const struct btf_type *t, int off, + int size, enum bpf_access_type atype, + u32 *next_btf_id, + enum bpf_type_flag *flag) +{ + const struct btf_type *sock_type; + struct btf *btf_vmlinux; + s32 type_id; + size_t end; + + if (atype == BPF_READ) + return btf_struct_access(log, btf, t, off, size, atype, next_btf_id, + flag); + + btf_vmlinux = bpf_get_btf_vmlinux(); + if (!btf_vmlinux) { + bpf_log(log, "no vmlinux btf\n"); + return -EOPNOTSUPP; + } + + type_id = btf_find_by_name_kind(btf_vmlinux, "sock", BTF_KIND_STRUCT); + if (type_id < 0) { + bpf_log(log, "'struct sock' not found in vmlinux btf\n"); + return -EINVAL; + } + + sock_type = btf_type_by_id(btf_vmlinux, type_id); + + if (t != sock_type) { + bpf_log(log, "only 'struct sock' writes are supported\n"); + return -EACCES; + } + + switch (off) { + case bpf_ctx_range(struct sock, sk_priority): + end = offsetofend(struct sock, sk_priority); + break; + case bpf_ctx_range(struct sock, sk_mark): + end = offsetofend(struct sock, sk_mark); + break; + default: + bpf_log(log, "no write support to 'struct sock' at off %d\n", off); + return -EACCES; + } + + if (off + size > end) { + bpf_log(log, + "write access at off %d with size %d beyond the member of 'struct sock' ended at %zu\n", + off, size, end); + return -EACCES; + } + + return NOT_INIT; +} + const struct bpf_verifier_ops lsm_verifier_ops = { .get_func_proto = bpf_lsm_func_proto, .is_valid_access = btf_ctx_access, + .btf_struct_access = lsm_btf_struct_access, }; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index caa5740b39b3..c54e171d9c23 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -13413,7 +13413,8 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env) insn->code = BPF_LDX | BPF_PROBE_MEM | BPF_SIZE((insn)->code); env->prog->aux->num_exentries++; - } else if (resolve_prog_type(env->prog) != BPF_PROG_TYPE_STRUCT_OPS) { + } else if (resolve_prog_type(env->prog) != BPF_PROG_TYPE_STRUCT_OPS && + resolve_prog_type(env->prog) != BPF_PROG_TYPE_LSM) { verbose(env, "Writes through BTF pointers are not allowed\n"); return -EINVAL; } -- 2.36.1.255.ge46751e96f-goog