Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754742AbaDGE7w (ORCPT ); Mon, 7 Apr 2014 00:59:52 -0400 Received: from ozlabs.org ([203.10.76.45]:36761 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750743AbaDGE71 (ORCPT ); Mon, 7 Apr 2014 00:59:27 -0400 From: Rusty Russell To: Linus Torvalds , Mateusz Guzik , Greg Kroah-Hartman Cc: Steven Rostedt , LKML , Andrew Morton , Thomas Gleixner , "H. Peter Anvin" , Borislav Petkov , Ingo Molnar , Mel Gorman , Kay Sievers Subject: Re: [RFC PATCH] cmdline: Hide "debug" from /proc/cmdline In-Reply-To: References: <20140402144219.4cafbe37@gandalf.local.home> <20140402221212.GD16570@mguzik.redhat.com> User-Agent: Notmuch/0.15.2 (http://notmuchmail.org) Emacs/23.4.1 (x86_64-pc-linux-gnu) Date: Mon, 07 Apr 2014 14:24:45 +0930 Message-ID: <87wqf1oi22.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Linus Torvalds writes: > On Wed, Apr 2, 2014 at 3:12 PM, Mateusz Guzik wrote: >> >> Well, parsing kernel cmdline by systemd is a bad idea > > No, we very much expose /proc/cmdline for a reason. System services > are *supposed* to parse it, because it gives a unified way for people > to pass in various flags. The kernel doesn't complain about flags it > doesn't recognize, exactly because the kernel realizes that "hey, > maybe this flag is for something else". How's this in future? Cheers, Rusty. Subject: param: hand arguments after -- straight to init The kernel passes any args it doesn't need through to init, except it assumes anything containing '.' belongs to the kernel (for a module). This change means all users can clearly distinguish which arguments are for init. For example, the kernel uses debug ("dee-bug") to mean log everything to the console, where systemd uses the debug from the Scandinavian "day-boog" meaning "fail to boot". If a future versions uses argv[] instead of reading /proc/cmdline, this confusion will be avoided. eg: test 'FOO="this is --foo"' -- 'systemd.debug="true true true"' Gives: argv[0] = '/debug-init' argv[1] = 'test' argv[2] = 'systemd.debug=true true true' envp[0] = 'HOME=/' envp[1] = 'TERM=linux' envp[2] = 'FOO=this is --foo' Signed-off-by: Rusty Russell diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index 204a67743804..b1990c5524e1 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -321,7 +321,7 @@ extern bool parameq(const char *name1, const char *name2); extern bool parameqn(const char *name1, const char *name2, size_t n); /* Called on module insert or kernel boot */ -extern int parse_args(const char *name, +extern char *parse_args(const char *name, char *args, const struct kernel_param *params, unsigned num, diff --git a/init/main.c b/init/main.c index 9c7fd4c9249f..e9d458b5d77b 100644 --- a/init/main.c +++ b/init/main.c @@ -252,6 +252,27 @@ static int __init repair_env_string(char *param, char *val, const char *unused) return 0; } +/* Anything after -- gets handed straight to init. */ +static int __init set_init_arg(char *param, char *val, const char *unused) +{ + unsigned int i; + + if (panic_later) + return 0; + + repair_env_string(param, val, unused); + + for (i = 0; argv_init[i]; i++) { + if (i == MAX_INIT_ARGS) { + panic_later = "init"; + panic_param = param; + return 0; + } + } + argv_init[i] = param; + return 0; +} + /* * Unknown boot options get handed to init, unless they look like * unused parameters (modprobe will find them in /proc/cmdline). @@ -478,7 +499,7 @@ static void __init mm_init(void) asmlinkage void __init start_kernel(void) { - char * command_line; + char * command_line, *after_dashes; extern const struct kernel_param __start___param[], __stop___param[]; /* @@ -519,9 +540,13 @@ asmlinkage void __init start_kernel(void) pr_notice("Kernel command line: %s\n", boot_command_line); parse_early_param(); - parse_args("Booting kernel", static_command_line, __start___param, - __stop___param - __start___param, - -1, -1, &unknown_bootoption); + after_dashes = parse_args("Booting kernel", + static_command_line, __start___param, + __stop___param - __start___param, + -1, -1, &unknown_bootoption); + if (after_dashes) + parse_args("Setting init args", after_dashes, NULL, 0, -1, -1, + set_init_arg); jump_label_init(); diff --git a/kernel/module.c b/kernel/module.c index 29f7790eaa14..600d1fbf1773 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -3193,6 +3193,7 @@ static int load_module(struct load_info *info, const char __user *uargs, { struct module *mod; long err; + char *after_dashes; err = module_sig_check(info); if (err) @@ -3277,10 +3278,15 @@ static int load_module(struct load_info *info, const char __user *uargs, goto ddebug_cleanup; /* Module is ready to execute: parsing args may do that. */ - err = parse_args(mod->name, mod->args, mod->kp, mod->num_kp, - -32768, 32767, unknown_module_param_cb); - if (err < 0) + after_dashes = parse_args(mod->name, mod->args, mod->kp, mod->num_kp, + -32768, 32767, unknown_module_param_cb); + if (IS_ERR(after_dashes)) { + err = PTR_ERR(after_dashes); goto bug_cleanup; + } else if (after_dashes) { + pr_warn("%s: parameters '%s' after `--' ignored\n", + mod->name, after_dashes); + } /* Link in to syfs. */ err = mod_sysfs_setup(mod, info, mod->kp, mod->num_kp); diff --git a/kernel/params.c b/kernel/params.c index b00142e7f3ba..1e52ca233fd9 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -177,13 +177,13 @@ static char *next_arg(char *args, char **param, char **val) } /* Args looks like "foo=bar,bar2 baz=fuz wiz". */ -int parse_args(const char *doing, - char *args, - const struct kernel_param *params, - unsigned num, - s16 min_level, - s16 max_level, - int (*unknown)(char *param, char *val, const char *doing)) +char *parse_args(const char *doing, + char *args, + const struct kernel_param *params, + unsigned num, + s16 min_level, + s16 max_level, + int (*unknown)(char *param, char *val, const char *doing)) { char *param, *val; @@ -198,6 +198,9 @@ int parse_args(const char *doing, int irq_was_disabled; args = next_arg(args, ¶m, &val); + /* Stop at -- */ + if (!val && strcmp(param, "--") == 0) + return args; irq_was_disabled = irqs_disabled(); ret = parse_one(param, val, doing, params, num, min_level, max_level, unknown); @@ -208,22 +211,22 @@ int parse_args(const char *doing, switch (ret) { case -ENOENT: pr_err("%s: Unknown parameter `%s'\n", doing, param); - return ret; + return ERR_PTR(ret); case -ENOSPC: pr_err("%s: `%s' too large for parameter `%s'\n", doing, val ?: "", param); - return ret; + return ERR_PTR(ret); case 0: break; default: pr_err("%s: `%s' invalid for parameter `%s'\n", doing, val ?: "", param); - return ret; + return ERR_PTR(ret); } } /* All parsed OK. */ - return 0; + return NULL; } /* Lazy bastard, eh? 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