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=-8.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 A5A0AC31E40 for ; Fri, 9 Aug 2019 15:32:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 590FB20C01 for ; Fri, 9 Aug 2019 15:32:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=fomichev-me.20150623.gappssmtp.com header.i=@fomichev-me.20150623.gappssmtp.com header.b="OPmRFYQx" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2436617AbfHIPcN (ORCPT ); Fri, 9 Aug 2019 11:32:13 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:38751 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2436608AbfHIPcN (ORCPT ); Fri, 9 Aug 2019 11:32:13 -0400 Received: by mail-pg1-f195.google.com with SMTP id z14so8804240pga.5 for ; Fri, 09 Aug 2019 08:32:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fomichev-me.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=z8obxCtqYi0AJWakTgLoiNjwfUmlWSuBvnJW1CvZOqw=; b=OPmRFYQxrJPZJm2/Oy786eOt570EfhKt8L9pPhIHA+nKkwk8fPVrIEc55oAHgNhkC8 lWDHAnRzTD/WPovc7OGwHf2LeYCY8nhzKYpO+rZ7x7UvtQ735N7qAZwKcsX4WyoIsSLU GQerOm2wR32WgZwK3C58rYOqGXUQKeYo5X9VbTqOXkG8RnZKnAqo/yPsY7cCOjTkkVRm 4gcfA00OrWpv3pkQg4SDxAmsfWan0RrY4JtJOBDM2EyzVg6Yr9Q6FyGP2Um8rRG/EJML qrCBCXYHit2guFlHBm2eq9y5FRhoF2yCopkDF9+YK7ZbXsCWjB629xWi5wQ0xtjzTtxo U+0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=z8obxCtqYi0AJWakTgLoiNjwfUmlWSuBvnJW1CvZOqw=; b=rusMbQepIErVD2qHZHHIWRLfmnEsUgPz6jh2bxZxd+IW5UgiLdrDWY02slMfISBI94 7JTcYuOnvmyOZlFNAycaMtaR58vHgj0UCm/jTw2zlXNMdPRN7cu2Zh70mptDDg0UXUMG XsqCRDED3/KGGanaQts67275ayxiXKH3JJUuWN6Ovi4NN3ANrGG1j0Dss7f9KKpv+5GP BG/cAprRXvdSfRD9zDiXtPfrdVOpEENQay2bkGBB7etNO2IPbj73joZWLn/Gfwk23ph8 K+L5pm72K/NKMBo7XbfLcaQsApfUHc1x1CYTOqxtwUH5YqugWfvC7HAtYcE84JHHlSOV 0J6w== X-Gm-Message-State: APjAAAWqz1Tcw1kFatRw6/eBu8+BZzQ8l6cB6XPDQrvJPjbqnlGxZDsT UGjQJFs3bEwSSyyKWpTndjUlTw== X-Google-Smtp-Source: APXvYqzgkqz3cduqaUHqyWdvPdTNy6bZqY6qn5l6Sp0hAKr8kZlrPSUg93DRvqEyopFjEzRQLqCUOQ== X-Received: by 2002:a62:2784:: with SMTP id n126mr22405505pfn.61.1565364732006; Fri, 09 Aug 2019 08:32:12 -0700 (PDT) Received: from localhost ([2601:646:8f00:18d9:d0fa:7a4b:764f:de48]) by smtp.gmail.com with ESMTPSA id t7sm100393089pfh.101.2019.08.09.08.32.11 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Fri, 09 Aug 2019 08:32:11 -0700 (PDT) Date: Fri, 9 Aug 2019 08:32:10 -0700 From: Stanislav Fomichev To: Peter Wu Cc: Alexei Starovoitov , Daniel Borkmann , netdev@vger.kernel.org, Stanislav Fomichev , Jakub Kicinski , Quentin Monnet Subject: Re: [PATCH v3] tools: bpftool: fix reading from /proc/config.gz Message-ID: <20190809153210.GD2820@mini-arch> References: <20190809003911.7852-1-peter@lekensteyn.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190809003911.7852-1-peter@lekensteyn.nl> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 08/09, Peter Wu wrote: > /proc/config has never existed as far as I can see, but /proc/config.gz > is present on Arch Linux. Add support for decompressing config.gz using > zlib which is a mandatory dependency of libelf. Replace existing stdio > functions with gzFile operations since the latter transparently handles > uncompressed and gzip-compressed files. > > Cc: Quentin Monnet > Signed-off-by: Peter Wu > --- > v3: replace popen(gunzip) by linking directly to zlib. Reword commit > message, remove "Fixes" line. (this patch) > v2: fix style (reorder vars as reverse xmas tree, rename function, > braces), fallback to /proc/config.gz if uname() fails. > https://lkml.kernel.org/r/20190806010702.3303-1-peter@lekensteyn.nl > v1: https://lkml.kernel.org/r/20190805001541.8096-1-peter@lekensteyn.nl > > Hi, > > Thanks to Jakub for observing that zlib is already used by libelf, this > simplifies the patch tremendously as the same API can be used for both > compressed and uncompressed files. No special case exists anymore for > fclose/pclose. > > According to configure.ac in elfutils, zlib is mandatory, so I just > assume it to be available. For simplicity I also silently assume lines > to be less than 4096 characters. If that is not the case, then lines > will appear truncated, but that should not be an issue for the > CONFIG_xyz lines that we are scanning for. > > Jakub requested the handle leak fix to be posted separately against the > bpf tree, but since the whole code is rewritten I am not sure if it is > worth it. It is an unusual edge case: /boot/config-$(uname -r) could be > opened, but starts with unexpected data. > > Kind regards, > Peter > --- > tools/bpf/bpftool/Makefile | 2 +- > tools/bpf/bpftool/feature.c | 105 ++++++++++++++++++------------------ > 2 files changed, 54 insertions(+), 53 deletions(-) > > diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile > index a7afea4dec47..078bd0dcfba5 100644 > --- a/tools/bpf/bpftool/Makefile > +++ b/tools/bpf/bpftool/Makefile > @@ -52,7 +52,7 @@ ifneq ($(EXTRA_LDFLAGS),) > LDFLAGS += $(EXTRA_LDFLAGS) > endif > > -LIBS = -lelf $(LIBBPF) > +LIBS = -lelf -lz $(LIBBPF) You're saying in the commit description that bpftool already links against -lz (via -lelf), but then explicitly add -lz here, why? > INSTALL ?= install > RM ?= rm -f > diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c > index d672d9086fff..03bdc5b3ac49 100644 > --- a/tools/bpf/bpftool/feature.c > +++ b/tools/bpf/bpftool/feature.c > @@ -14,6 +14,7 @@ > > #include > #include > +#include > > #include "main.h" > > @@ -284,34 +285,32 @@ static void probe_jit_limit(void) > } > } > > -static char *get_kernel_config_option(FILE *fd, const char *option) > +static bool read_next_kernel_config_option(gzFile file, char *buf, size_t n, > + char **value) > { > - size_t line_n = 0, optlen = strlen(option); > - char *res, *strval, *line = NULL; > - ssize_t n; > + char *sep; > > - rewind(fd); > - while ((n = getline(&line, &line_n, fd)) > 0) { > - if (strncmp(line, option, optlen)) > + while (gzgets(file, buf, n)) { > + if (strncmp(buf, "CONFIG_", 7)) > continue; > - /* Check we have at least '=', value, and '\n' */ > - if (strlen(line) < optlen + 3) > - continue; > - if (*(line + optlen) != '=') > + > + sep = strchr(buf, '='); > + if (!sep) > continue; > > /* Trim ending '\n' */ > - line[strlen(line) - 1] = '\0'; > + buf[strlen(buf) - 1] = '\0'; > + > + /* Split on '=' and ensure that a value is present. */ > + *sep = '\0'; > + if (!sep[1]) > + continue; > > - /* Copy and return config option value */ > - strval = line + optlen + 1; > - res = strdup(strval); > - free(line); > - return res; > + *value = sep + 1; > + return true; > } > - free(line); > > - return NULL; > + return false; > } > > static void probe_kernel_image_config(void) > @@ -386,59 +385,61 @@ static void probe_kernel_image_config(void) > /* test_bpf module for BPF tests */ > "CONFIG_TEST_BPF", > }; > - char *value, *buf = NULL; > + char *values[ARRAY_SIZE(options)] = { }; > struct utsname utsn; > char path[PATH_MAX]; > - size_t i, n; > - ssize_t ret; > - FILE *fd; > + gzFile file = NULL; > + char buf[4096]; > + char *value; > + size_t i; > > - if (uname(&utsn)) > - goto no_config; > + if (!uname(&utsn)) { > + snprintf(path, sizeof(path), "/boot/config-%s", utsn.release); > > - snprintf(path, sizeof(path), "/boot/config-%s", utsn.release); > + /* gzopen also accepts uncompressed files. */ > + file = gzopen(path, "r"); > + } > > - fd = fopen(path, "r"); > - if (!fd && errno == ENOENT) { > - /* Some distributions put the config file at /proc/config, give > - * it a try. > - * Sometimes it is also at /proc/config.gz but we do not try > - * this one for now, it would require linking against libz. > + if (!file) { > + /* Some distributions build with CONFIG_IKCONFIG=y and put the > + * config file at /proc/config.gz. > */ > - fd = fopen("/proc/config", "r"); > + file = gzopen("/proc/config.gz", "r"); > } > - if (!fd) { > + if (!file) { > p_info("skipping kernel config, can't open file: %s", > strerror(errno)); > - goto no_config; > + goto end_parse; > } > /* Sanity checks */ > - ret = getline(&buf, &n, fd); > - ret = getline(&buf, &n, fd); > - if (!buf || !ret) { > + if (!gzgets(file, buf, sizeof(buf)) || > + !gzgets(file, buf, sizeof(buf))) { > p_info("skipping kernel config, can't read from file: %s", > strerror(errno)); > - free(buf); > - goto no_config; > + goto end_parse; > } > if (strcmp(buf, "# Automatically generated file; DO NOT EDIT.\n")) { > p_info("skipping kernel config, can't find correct file"); > - free(buf); > - goto no_config; > + goto end_parse; > } > - free(buf); > > - for (i = 0; i < ARRAY_SIZE(options); i++) { > - value = get_kernel_config_option(fd, options[i]); > - print_kernel_option(options[i], value); > - free(value); > + while (read_next_kernel_config_option(file, buf, sizeof(buf), &value)) { > + for (i = 0; i < ARRAY_SIZE(options); i++) { > + if (values[i] || strcmp(buf, options[i])) > + continue; > + > + values[i] = strdup(value); > + } > } > - fclose(fd); > - return; > > -no_config: > - for (i = 0; i < ARRAY_SIZE(options); i++) > - print_kernel_option(options[i], NULL); > +end_parse: > + if (file) > + gzclose(file); > + > + for (i = 0; i < ARRAY_SIZE(options); i++) { > + print_kernel_option(options[i], values[i]); > + free(values[i]); > + } > } > > static bool probe_bpf_syscall(const char *define_prefix) > -- > 2.22.0 >