From patchwork Fri Apr 5 19:35:25 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Ignatov X-Patchwork-Id: 10887771 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 4FDD417E0 for ; Fri, 5 Apr 2019 19:36:44 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3A63E28B03 for ; Fri, 5 Apr 2019 19:36:44 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2DD6E28B5C; Fri, 5 Apr 2019 19:36:44 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A081328B03 for ; Fri, 5 Apr 2019 19:36:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731891AbfDETgm (ORCPT ); Fri, 5 Apr 2019 15:36:42 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:44042 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731878AbfDETgl (ORCPT ); Fri, 5 Apr 2019 15:36:41 -0400 Received: from pps.filterd (m0109334.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x35JWdoh028131 for ; Fri, 5 Apr 2019 12:36:40 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=facebook; bh=Rs9aC4INCN0Ckm8XaMAHgUlhKH7k4XDjyx5oxEZ4TL4=; b=Wl85TsaIxs/L1fcvBhGLqvGopf35JXf7m2Mc842bEeEXcgxrcQGpHbpT8ebkR6oJLhj/ e7ZmFCkxCEppqR82tTD/LLrp3eKZHB7dQESstrknZNy4htmiBUlDKybXtWyYgZAUDb9k ZZj2HWNi7g/MGqqvgfcdNZqg+ezAQb24iAM= Received: from maileast.thefacebook.com ([199.201.65.23]) by mx0a-00082601.pphosted.com with ESMTP id 2rpbqc0c3f-11 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT) for ; Fri, 05 Apr 2019 12:36:40 -0700 Received: from mx-out.facebook.com (2620:10d:c0a1:3::13) by mail.thefacebook.com (2620:10d:c021:18::174) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA) id 15.1.1713.5; Fri, 5 Apr 2019 12:36:30 -0700 Received: by dev082.prn2.facebook.com (Postfix, from userid 572249) id 90ED93701752; Fri, 5 Apr 2019 12:36:27 -0700 (PDT) Smtp-Origin-Hostprefix: dev From: Andrey Ignatov Smtp-Origin-Hostname: dev082.prn2.facebook.com To: CC: Andrey Ignatov , , , , , Luis Chamberlain , Kees Cook , Alexey Dobriyan , , Smtp-Origin-Cluster: prn2c23 Subject: [PATCH v3 bpf-next 03/21] bpf: Introduce bpf_sysctl_get_name helper Date: Fri, 5 Apr 2019 12:35:25 -0700 Message-ID: <2d86e38658fbb0d0e9384692a72b2a5acf239ae0.1554485409.git.rdna@fb.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: References: X-FB-Internal: Safe MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-04-05_15:,, signatures=0 X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add bpf_sysctl_get_name() helper to copy sysctl name (/proc/sys/ entry) into provided by BPF_PROG_TYPE_CGROUP_SYSCTL program buffer. By default full name (w/o /proc/sys/) is copied, e.g. "net/ipv4/tcp_mem". If BPF_F_SYSCTL_BASE_NAME flag is set, only base name will be copied, e.g. "tcp_mem". Documentation for the new helper is provided in bpf.h UAPI. Signed-off-by: Andrey Ignatov --- include/uapi/linux/bpf.h | 22 ++++++++++++- kernel/bpf/cgroup.c | 70 +++++++++++++++++++++++++++++++++++++++- 2 files changed, 90 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 4cfda9c16327..c9e8a1f22c14 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2479,6 +2479,22 @@ union bpf_attr { * Return * 0 if iph and th are a valid SYN cookie ACK, or a negative error * otherwise. + * + * int bpf_sysctl_get_name(struct bpf_sysctl *ctx, char *buf, size_t buf_len, u64 flags) + * Description + * Get name of sysctl in /proc/sys/ and copy it into provided by + * program buffer *buf* of size *buf_len*. + * + * The buffer is always NUL terminated, unless it's zero-sized. + * + * If *flags* is zero, full name (e.g. "net/ipv4/tcp_mem") is + * copied. Use **BPF_F_SYSCTL_BASE_NAME** flag to copy base name + * only (e.g. "tcp_mem"). + * Return + * Number of character copied (not including the trailing NUL). + * + * **-E2BIG** if the buffer wasn't big enough (*buf* will contain + * truncated name in this case). */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -2581,7 +2597,8 @@ union bpf_attr { FN(skb_ecn_set_ce), \ FN(get_listener_sock), \ FN(skc_lookup_tcp), \ - FN(tcp_check_syncookie), + FN(tcp_check_syncookie), \ + FN(sysctl_get_name), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call @@ -2648,6 +2665,9 @@ enum bpf_func_id { #define BPF_F_ADJ_ROOM_ENCAP_L4_GRE (1ULL << 3) #define BPF_F_ADJ_ROOM_ENCAP_L4_UDP (1ULL << 4) +/* BPF_FUNC_sysctl_get_name flags. */ +#define BPF_F_SYSCTL_BASE_NAME (1ULL << 0) + /* Mode for BPF_FUNC_skb_adjust_room helper. */ enum bpf_adj_room_mode { BPF_ADJ_ROOM_NET, diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c index 610491b5f0aa..a68387043244 100644 --- a/kernel/bpf/cgroup.c +++ b/kernel/bpf/cgroup.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include @@ -806,10 +807,77 @@ int __cgroup_bpf_run_filter_sysctl(struct ctl_table_header *head, } EXPORT_SYMBOL(__cgroup_bpf_run_filter_sysctl); +static ssize_t sysctl_cpy_dir(const struct ctl_dir *dir, char **bufp, + size_t *lenp) +{ + ssize_t tmp_ret = 0, ret; + + if (dir->header.parent) { + tmp_ret = sysctl_cpy_dir(dir->header.parent, bufp, lenp); + if (tmp_ret < 0) + return tmp_ret; + } + + ret = strscpy(*bufp, dir->header.ctl_table[0].procname, *lenp); + if (ret < 0) + return ret; + *bufp += ret; + *lenp -= ret; + ret += tmp_ret; + + /* Avoid leading slash. */ + if (!ret) + return ret; + + tmp_ret = strscpy(*bufp, "/", *lenp); + if (tmp_ret < 0) + return tmp_ret; + *bufp += tmp_ret; + *lenp -= tmp_ret; + + return ret + tmp_ret; +} + +BPF_CALL_4(bpf_sysctl_get_name, struct bpf_sysctl_kern *, ctx, char *, buf, + size_t, buf_len, u64, flags) +{ + ssize_t tmp_ret = 0, ret; + + if (!buf) + return -EINVAL; + + if (!(flags & BPF_F_SYSCTL_BASE_NAME)) { + if (!ctx->head) + return -EINVAL; + tmp_ret = sysctl_cpy_dir(ctx->head->parent, &buf, &buf_len); + if (tmp_ret < 0) + return tmp_ret; + } + + ret = strscpy(buf, ctx->table->procname, buf_len); + + return ret < 0 ? ret : tmp_ret + ret; +} + +static const struct bpf_func_proto bpf_sysctl_get_name_proto = { + .func = bpf_sysctl_get_name, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_CTX, + .arg2_type = ARG_PTR_TO_MEM, + .arg3_type = ARG_CONST_SIZE, + .arg4_type = ARG_ANYTHING, +}; + static const struct bpf_func_proto * sysctl_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { - return cgroup_base_func_proto(func_id, prog); + switch (func_id) { + case BPF_FUNC_sysctl_get_name: + return &bpf_sysctl_get_name_proto; + default: + return cgroup_base_func_proto(func_id, prog); + } } static bool sysctl_is_valid_access(int off, int size, enum bpf_access_type type,