On Wed, Oct 01, 2014 at 03:56:41PM -0700, Andy Lutomirski wrote:
> 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 is unexpected but probably harmless. 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 config option CONFIG_INIT_FALLBACK. If unset,
> then a failure to run the specified init= process be fatal.
>
> The intent is to switch the default to N after a while and to
> possibly even remove the option entirely
>
> Signed-off-by: Andy Lutomirski <l...@amacapital.net>
Nit: why does this patch gratuitously change the indentation of the
second line of pr_err?
That aside:
Reviewed-by: Josh Triplett <j...@joshtriplett.org>
>
> Changes from v4:
> - Switch the default to y
>
> Changes from v3:
> - Get rid of the strictinit option. Now the new behavior is the default
> unless CONFIG_INIT_FALLBACK=y (Rob Landley)
>
> Changes from v2:
> - Improve docs further, to leave the door open to giving strictinit
> some sensible semantics if init= is not set.
> - Improve error output in the failure case (Shuah Khan).
>
> Changes from v1:
> - Add missing "if" to the docs (Randy Dunlap)
>
> init/Kconfig | 16 ++++++++++++++++
> init/main.c | 7 ++++++-
> 2 files changed, 22 insertions(+), 1 deletion(-)
>
> diff --git a/init/Kconfig b/init/Kconfig
> index e84c6423a2e5..ebbd5846478e 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1299,6 +1299,22 @@ source "usr/Kconfig"
>
> endif
>
> +config INIT_FALLBACK
> + bool "Fall back to defaults if init= parameter is bad"
> + default y
> + help
> + If enabled, the kernel will try the default init binaries if an
> + explicit request from the init= parameter fails.
> +
> + This can have unexpected effects. For example, booting
> + with init=/sbin/kiosk_app will run /sbin/init or even /bin/sh
> + if /sbin/kiosk_app cannot be executed.
> +
> + The default value of Y is consistent with historical behavior.
> + Selecting N is likely to be more appropriate for most uses,
> + especially on kiosks and on kernels that are indended to be
> + run under the control of a script.
> +
> config CC_OPTIMIZE_FOR_SIZE
> bool "Optimize for size"
> help
> diff --git a/init/main.c b/init/main.c
> index bb1aed928f21..2bd6105e5dc5 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -960,8 +960,13 @@ static int __ref kernel_init(void *unused)
> ret = run_init_process(execute_command);
> if (!ret)
> return 0;
> +#ifndef CONFIG_INIT_FALLBACK
> + panic("Requested init %s failed (error %d).",
> + execute_command, ret);
> +#else
> pr_err("Failed to execute %s (error %d). Attempting
> defaults...\n",
> - execute_command, ret);
> + execute_command, ret);
> +#endif
> }
> if (!try_to_run_init_process("/sbin/init") ||
> !try_to_run_init_process("/etc/init") ||
> --
> 1.9.3
>
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