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=-14.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable 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 98E3CC43603 for ; Mon, 16 Dec 2019 18:30:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 677C0207FF for ; Mon, 16 Dec 2019 18:30:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Px/lX10T" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731195AbfLPSaW (ORCPT ); Mon, 16 Dec 2019 13:30:22 -0500 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:21118 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731011AbfLPSMw (ORCPT ); Mon, 16 Dec 2019 13:12:52 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1576519970; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=gG9VGGPZ6c4OJ26G78LddjiW5k2zffvrFpUIDfVi4Vk=; b=Px/lX10TfCWwZ/WYWXUxqE9S9sYQH8FJ3zjcGYfN431OwjODWtxAqQYXnr6EQeE+4i4N6W ixWjT1wpnIdzKWH9I5oVD6fx417QevFJlwd3JRHIMOMBVzegE4eZXYYS/JgTXwLtluolQB ZzcqHh6w2WtpSp8MKSpSCMJjjFi2Yds= Received: from mail-lj1-f197.google.com (mail-lj1-f197.google.com [209.85.208.197]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-256-RPQyEhq4M1C6JYqzK4ZbUw-1; Mon, 16 Dec 2019 13:12:49 -0500 X-MC-Unique: RPQyEhq4M1C6JYqzK4ZbUw-1 Received: by mail-lj1-f197.google.com with SMTP id q191so2355894ljb.8 for ; Mon, 16 Dec 2019 10:12:49 -0800 (PST) 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=gG9VGGPZ6c4OJ26G78LddjiW5k2zffvrFpUIDfVi4Vk=; b=ASc1ODsIgzv2FfRhNsYsXpDgXxs+h/AYKaXf32WoovVTb91gPXP0eMd0iWTkWoMhkL LUyDxwoCNUuuyFedZD5tM4HyOfkIbNFnWHnvOaym2hAKvuwwMWAfGrQwo5dv5OROH7pk 8OCdn9Pc/DYAW0ImJKVY39LtzxGijz3NGpvNiwn55lDQXNO2snWXC0B9/J6E/ZtP/UHc jszq8CmrE2SM856bPRWIU0vLTV5tDQioHLFBidiHXHtXB/FXJKIjuafB92Jmer9bbbov sn+n9rytAjIoWHB5XaBhPOJFJugwxBX9HshNBHWfLAOEv2nyVIg0uGAkzEQ6TPcLUR7S gZ1w== X-Gm-Message-State: APjAAAVyrHzDOxjxH38idtXoOHSeryrOyJ6FipfwTs6RJYdHKOcehe8U RoHQdM+IO/UHILurgq1rAcRRKBwMQ8Y8mlD9s77cV1B3QJpw9i1y9pHkdBnV4SgseTKsVLke4P8 MM+HQ4X5SuIvk X-Received: by 2002:a2e:8797:: with SMTP id n23mr298319lji.176.1576519967825; Mon, 16 Dec 2019 10:12:47 -0800 (PST) X-Google-Smtp-Source: APXvYqzib2wPbukcLs24+rc6P5JH52a4OsCYyY8YkGjR2Epph9CQfUt9aPxH1qqr+PIhM8j16xM9cw== X-Received: by 2002:a2e:8797:: with SMTP id n23mr298286lji.176.1576519967369; Mon, 16 Dec 2019 10:12:47 -0800 (PST) Received: from alrua-x1.borgediget.toke.dk ([45.145.92.2]) by smtp.gmail.com with ESMTPSA id q25sm11160992lji.7.2019.12.16.10.12.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Dec 2019 10:12:46 -0800 (PST) Received: by alrua-x1.borgediget.toke.dk (Postfix, from userid 1000) id CDDF7180960; Mon, 16 Dec 2019 19:12:45 +0100 (CET) From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= To: Alexei Starovoitov , Daniel Borkmann Cc: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= , netdev@vger.kernel.org, bpf@vger.kernel.org, Jesper Dangaard Brouer , Yonghong Song Subject: [PATCH bpf-next v2] libbpf: Print hint about ulimit when getting permission denied error Date: Mon, 16 Dec 2019 19:12:04 +0100 Message-Id: <20191216181204.724953-1-toke@redhat.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Probably the single most common error newcomers to XDP are stumped by is the 'permission denied' error they get when trying to load their program and 'ulimit -l' is set too low. For examples, see [0], [1]. Since the error code is UAPI, we can't change that. Instead, this patch adds a few heuristics in libbpf and outputs an additional hint if they are met: If an EPERM is returned on map create or program load, and geteuid() shows we are root, and the current RLIMIT_MEMLOCK is not infinity, we output a hint about raising 'ulimit -l' as an additional log line. [0] https://marc.info/?l=xdp-newbies&m=157043612505624&w=2 [1] https://github.com/xdp-project/xdp-tutorial/issues/86 Acked-by: Jesper Dangaard Brouer Acked-by: Yonghong Song Signed-off-by: Toke Høiland-Jørgensen --- v2: - Format current output as KiB/MiB - It's ulimit -l, not ulimit -r tools/lib/bpf/libbpf.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index a2cc7313763a..3fe42d6b0c2f 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -41,6 +41,7 @@ #include #include #include +#include #include #include #include @@ -100,6 +101,32 @@ void libbpf_print(enum libbpf_print_level level, const char *format, ...) va_end(args); } +static void pr_perm_msg(int err) +{ + struct rlimit limit; + char buf[100]; + + if (err != -EPERM || geteuid() != 0) + return; + + err = getrlimit(RLIMIT_MEMLOCK, &limit); + if (err) + return; + + if (limit.rlim_cur == RLIM_INFINITY) + return; + + if (limit.rlim_cur < 1024) + snprintf(buf, sizeof(buf), "%lu bytes", limit.rlim_cur); + else if (limit.rlim_cur < 1024*1024) + snprintf(buf, sizeof(buf), "%.1f KiB", (double)limit.rlim_cur / 1024); + else + snprintf(buf, sizeof(buf), "%.1f MiB", (double)limit.rlim_cur / (1024*1024)); + + pr_warn("permission error while running as root; try raising 'ulimit -l'? current value: %s\n", + buf); +} + #define STRERR_BUFSIZE 128 /* Copied from tools/perf/util/util.h */ @@ -2983,6 +3010,7 @@ bpf_object__create_maps(struct bpf_object *obj) cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg)); pr_warn("failed to create map (name: '%s'): %s(%d)\n", map->name, cp, err); + pr_perm_msg(err); for (j = 0; j < i; j++) zclose(obj->maps[j].fd); return err; @@ -4381,6 +4409,7 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, ret = -errno; cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); pr_warn("load bpf program failed: %s\n", cp); + pr_perm_msg(ret); if (log_buf && log_buf[0] != '\0') { ret = -LIBBPF_ERRNO__VERIFY; -- 2.24.1