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 4B2C4C433EF for ; Tue, 19 Apr 2022 19:01:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1357454AbiDSTEH (ORCPT ); Tue, 19 Apr 2022 15:04:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1357504AbiDSTEE (ORCPT ); Tue, 19 Apr 2022 15:04:04 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7C9AC3F314 for ; Tue, 19 Apr 2022 12:01:10 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id j11-20020a05690212cb00b006454988d225so1171555ybu.10 for ; Tue, 19 Apr 2022 12:01:10 -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=WsbIvWJzyW+xGxjw/3+rbSUhNFPySw8SJoOh+xXQbd0=; b=bbqNhgU0thhNE2t0TRW3C3wZT5PDQJLOeRL6fJh2uakx13B7qwlZiw32zw5m+kRKR1 BmkBSHJEj/M2yck1xK/LJWSrBdG3o4Y3YpKH0vYMf/RYeEVV4PthAza0Y758NE3Vo0Tj 6L1bsvm7jur20cOaKgSgQ9ZettlU2sCjYT+14d0ZUu8dAI8pP4KRUFFL1Mfooe0PpEAe VDZkIuiBZ2MVzZOSBmORkI9V3grLBZmqvRzdCRQ0Wj2hwvNlIThYk02rooZ1P0mqn8q9 OosPVFGlmMKDwamOhQ3NdrY3MEqw8qrEKS4ul55yOmOsReJ/1sf4jSaxp5nwq7bFnowT HT3Q== 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=WsbIvWJzyW+xGxjw/3+rbSUhNFPySw8SJoOh+xXQbd0=; b=rGxIFv7n9/gdUXpoduOlHT7a3Dxcr08ByLsPbEJiH7nR+oi+fgnISt3qaxFIPYGkoV M3C+ytCRGBkzR4q3wSywAg4cdmyqQ2d32PiKNpG8Hc0eBcF3XcfwCU0AHiWl2z7dDig5 CI8rlPTMvG9RbI4xzaBYy+8+VaHBXhtAlmbn0NRupnT7fjtJs+njvcrXKWcoVNfDpuNb 9o2a95Sm5Fvqwh/GZzZ7hLYL0A/tPCqcY5o8jTudT3yB4mw/MfIEXx4CAS3KA+VC/SQt XvOn+qmY1bKsybZH9tQcrM3axE71wV/2KKllxuqTFh4qgE3knAicfiVf5cdmRHkTSCe8 HjvQ== X-Gm-Message-State: AOAM533wD/w0w3I7C0DMkKXqHP8pj54KBfxzYV3QRvu5gp6JrX7ELCEx dRkJhFapSJIT+9J3Z1YXsNstNQQ= X-Google-Smtp-Source: ABdhPJyo13oHyEWyEmnxqb/sF/lXonDDeo6pSOqbpHewg2xxqivDPkFoeaBPdVGClAgz1uuLaW0xne0= X-Received: from sdf2.svl.corp.google.com ([2620:15c:2c4:201:37f:6746:8e66:a291]) (user=sdf job=sendgmr) by 2002:a5b:cd:0:b0:641:6d0c:30f5 with SMTP id d13-20020a5b00cd000000b006416d0c30f5mr16086598ybp.489.1650394869742; Tue, 19 Apr 2022 12:01:09 -0700 (PDT) Date: Tue, 19 Apr 2022 12:00:50 -0700 In-Reply-To: <20220419190053.3395240-1-sdf@google.com> Message-Id: <20220419190053.3395240-6-sdf@google.com> Mime-Version: 1.0 References: <20220419190053.3395240-1-sdf@google.com> X-Mailer: git-send-email 2.36.0.rc0.470.gd361397f0d-goog Subject: [PATCH bpf-next v5 5/8] 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 7f8a631da90f..d49663685946 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -301,7 +301,65 @@ 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 cc84954846d7..0d6d5be30a36 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -12872,7 +12872,8 @@ 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; } -- 2.36.0.rc0.470.gd361397f0d-goog