From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754652AbaIZTOG (ORCPT ); Fri, 26 Sep 2014 15:14:06 -0400 Received: from mail-pd0-f180.google.com ([209.85.192.180]:50325 "EHLO mail-pd0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752457AbaIZTOE (ORCPT ); Fri, 26 Sep 2014 15:14:04 -0400 From: Andy Lutomirski To: Andrew Morton , linux-kernel@vger.kernel.org Cc: Randy Dunlap , Shuah Khan , Rusty Russell , Andy Lutomirski Subject: [PATCH v3] init: Add strictinit to disable init= fallbacks Date: Fri, 26 Sep 2014 12:13:57 -0700 Message-Id: <138a894f22366da4173c8a4f2bfb0e670c66dbec.1411758752.git.luto@amacapital.net> X-Mailer: git-send-email 1.9.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If a user puts init=/whatever on the command line and /whatever can't be run, then the kernel will try a few default options before giving up. If init=/whatever came from a bootloader prompt, then this probably makes sense. On the other hand, if it comes from a script (e.g. a tool like virtme or perhaps a future kselftest script), then the fallbacks are likely to exist, but they'll do the wrong thing. For example, they might unexpectedly invoke systemd. This adds a new option called strictinit. If init= and strictinit are both set, and the init= binary is not executable, then the kernel will panic immediately. If strictinit is set but init= is not set, then strictinit will have no effect, because the only real alternative would be to panic regardless of the contents of the root fs. Signed-off-by: Andy Lutomirski --- Documentation/kernel-parameters.txt | 8 ++++++++ init/main.c | 16 ++++++++++++++-- 2 files changed, 22 insertions(+), 2 deletions(-) diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 10d51c2f10d7..1576273edce6 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -3236,6 +3236,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted. stifb= [HW] Format: bpp:[:[:...]] + strictinit [KNL,BOOT] + Normally, if the kernel can't find the init binary + specified by rdinit= and/or init=, then it will + try several fallbacks. If strictinit is set + and the value specified by init= does not work, + then the kernel will panic instead. + This option makes no sense if init= is not specified. + sunrpc.min_resvport= sunrpc.max_resvport= [NFS,SUNRPC] diff --git a/init/main.c b/init/main.c index bb1aed928f21..2ae0f2776155 100644 --- a/init/main.c +++ b/init/main.c @@ -131,6 +131,7 @@ static char *initcall_command_line; static char *execute_command; static char *ramdisk_execute_command; +static bool strictinit; /* * Used to generate warnings if static_key manipulation functions are used @@ -347,6 +348,13 @@ static int __init rdinit_setup(char *str) } __setup("rdinit=", rdinit_setup); +static int __init strictinit_setup(char *str) +{ + strictinit = true; + return 1; +} +__setup("strictinit", strictinit_setup); + #ifndef CONFIG_SMP static const unsigned int setup_max_cpus = NR_CPUS; #ifdef CONFIG_X86_LOCAL_APIC @@ -960,8 +968,12 @@ static int __ref kernel_init(void *unused) ret = run_init_process(execute_command); if (!ret) return 0; - pr_err("Failed to execute %s (error %d). Attempting defaults...\n", - execute_command, ret); + if (strictinit) + panic("Requested init %s failed (error %d) and strictinit was set.", + execute_command, ret); + else + pr_err("Failed to execute %s (error %d). Attempting defaults...\n", + execute_command, ret); } if (!try_to_run_init_process("/sbin/init") || !try_to_run_init_process("/etc/init") || -- 1.9.3