From patchwork Mon Oct 26 06:36:34 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wang Nan X-Patchwork-Id: 55521 Delivered-To: patch@linaro.org Received: by 10.112.59.35 with SMTP id w3csp1019935lbq; Sun, 25 Oct 2015 23:37:23 -0700 (PDT) X-Received: by 10.67.6.161 with SMTP id cv1mr20044494pad.131.1445841443061; Sun, 25 Oct 2015 23:37:23 -0700 (PDT) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id h4si51000728pat.71.2015.10.25.23.37.22; Sun, 25 Oct 2015 23:37:23 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753192AbbJZGhT (ORCPT + 28 others); Mon, 26 Oct 2015 02:37:19 -0400 Received: from szxga02-in.huawei.com ([119.145.14.65]:47263 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750982AbbJZGhR (ORCPT ); Mon, 26 Oct 2015 02:37:17 -0400 Received: from 172.24.1.49 (EHLO SZXEML424-HUB.china.huawei.com) ([172.24.1.49]) by szxrg02-dlp.huawei.com (MOS 4.3.7-GA FastPath queued) with ESMTP id CVB13871; Mon, 26 Oct 2015 14:36:55 +0800 (CST) Received: from linux-4hy3.site (10.107.193.248) by SZXEML424-HUB.china.huawei.com (10.82.67.153) with Microsoft SMTP Server id 14.3.235.1; Mon, 26 Oct 2015 14:36:42 +0800 From: Wang Nan To: , CC: , , , Wang Nan , Arnaldo Carvalho de Melo , "David S. Miller" Subject: [net-next PATCH] bpf: Output error message to logbuf when loading Date: Mon, 26 Oct 2015 06:36:34 +0000 Message-ID: <1445841394-142865-1-git-send-email-wangnan0@huawei.com> X-Mailer: git-send-email 1.8.3.4 MIME-Version: 1.0 X-Originating-IP: [10.107.193.248] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Many reason can make bpf_prog_load() return EINVAL. This patch utilizes logbuf passed from user to deliver the actual reason of failure. Without this patch, people is easy to forget fixing the "version" section in their BPF objects. Signed-off-by: Wang Nan Cc: Alexei Starovoitov Cc: Arnaldo Carvalho de Melo Cc: David S. Miller --- kernel/bpf/syscall.c | 41 ++++++++++++++++++++++++++++++++++++++--- 1 file changed, 38 insertions(+), 3 deletions(-) -- 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 687dd6c..3a0e4e7 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -574,6 +574,32 @@ struct bpf_prog *bpf_prog_get(u32 ufd) } EXPORT_SYMBOL_GPL(bpf_prog_get); +static void +bpf_prog_load_note(union bpf_attr *attr, const char *fmt, ...) +{ + u32 log_level, log_size, log_len; + char __user *log_ubuf = NULL; + /* 64 chars should be long enough for a one line note. */ + char log_buf[64]; + va_list args; + + log_ubuf = (char __user *) (unsigned long) attr->log_buf; + log_level = attr->log_level; + log_size = sizeof(log_buf); + if (attr->log_size < log_size) + log_size = attr->log_size; + + if (log_level == 0 || !log_size || !log_ubuf) + return; + + va_start(args, fmt); + log_len = vscnprintf(log_buf, log_size, fmt, args); + va_end(args); + + /* Don't need to care the copying result too much */ + copy_to_user(log_ubuf, log_buf, log_size); +} + /* last field in 'union bpf_attr' used by this command */ #define BPF_PROG_LOAD_LAST_FIELD kern_version @@ -597,12 +623,19 @@ static int bpf_prog_load(union bpf_attr *attr) /* eBPF programs must be GPL compatible to use GPL-ed functions */ is_gpl = license_is_gpl_compatible(license); - if (attr->insn_cnt >= BPF_MAXINSNS) + if (attr->insn_cnt >= BPF_MAXINSNS) { + bpf_prog_load_note(attr, "Too many instructions: %d > %d\n", + attr->insn_cnt, BPF_MAXINSNS); return -EINVAL; + } if (type == BPF_PROG_TYPE_KPROBE && - attr->kern_version != LINUX_VERSION_CODE) + attr->kern_version != LINUX_VERSION_CODE) { + bpf_prog_load_note(attr, + "Kernel version mismatch: 0x%x != 0x%x\n", + attr->kern_version, LINUX_VERSION_CODE); return -EINVAL; + } if (type != BPF_PROG_TYPE_SOCKET_FILTER && !capable(CAP_SYS_ADMIN)) return -EPERM; @@ -631,8 +664,10 @@ static int bpf_prog_load(union bpf_attr *attr) /* find program type: socket_filter vs tracing_filter */ err = find_prog_type(type, prog); - if (err < 0) + if (err < 0) { + bpf_prog_load_note(attr, "Invalid program type: %d\n", type); goto free_prog; + } /* run eBPF verifier */ err = bpf_check(&prog, attr);