Re: [PATCH v2 4/4] param: convert some "on"/"off" users to strtobool

From: Kees Cook
Date: Thu Feb 04 2016 - 19:11:49 EST

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On Thu, Feb 4, 2016 at 3:04 PM, Andy Shevchenko
<andy.shevchenko@xxxxxxxxx> wrote:
> On Thu, Feb 4, 2016 at 11:00 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>> This changes several users of manual "on"/"off" parsing to use strtobool.
>> (Which means they will now parse y/n/1/0 meaningfully too.)
>>
>
> I like this change, but can you carefully check the acceptance of the
> returned value?
> Briefly I saw 1 or 0 as okay in different places.

Maybe I missed something, but I think this is actually a bug fix. The
two cases are early_param and __setup:

For early_param, the functions are called when walking the command
line in do_early_param via parse_args in parse_early_options. Any
non-zero return values produce a warning (in do_early_param not
parse_args). So this is a bug fix, since the function I touched would
(almost) always return 0, even with bad values (i.e. fixes unreported
bad arguments):

early_param early_parse_stp always 0
early_param early_parse_topology always 0
early_param parse_gart_mem always 0 unless !p (then -EINVAL)

For __setup, these are handled by obsolete_checksetup via
unknown_bootoption via parse_args in start_kernel, as a way to merge
__setup calls that should really be in param (i.e. non-early __setup).
Return values are bubbled up into parse_args and hit:

default:
pr_err("%s: `%s' invalid for parameter `%s'\n",
doing, val ?: "", param);
break;

So this is also a bug fix, since these __setup functions returned inverted
values or always failed:

__setup rtasmsgs_setup always 1
__setup setup_cede_offline 1 on success, otherwise 0
__setup setup_hrtimer_hres 1 on success, otherwise 0
__setup setup_tick_nohz 1 on success, otherwise 0

So if you specified any of these, they would trigger a bogus "invalid
parameter" report.

I will double-check...

-Kees

>
>
>> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
>> Acked-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
>> Acked-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
>> Cc: x86@xxxxxxxxxx
>> Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
>> Cc: linux-s390@xxxxxxxxxxxxxxx
>> ---
>> arch/powerpc/kernel/rtasd.c | 9 ++-------
>> arch/powerpc/platforms/pseries/hotplug-cpu.c | 10 ++--------
>> arch/s390/kernel/time.c | 8 ++------
>> arch/s390/kernel/topology.c | 7 ++-----
>> arch/x86/kernel/aperture_64.c | 12 ++----------
>> include/linux/tick.h | 2 +-
>> kernel/time/hrtimer.c | 10 ++--------
>> kernel/time/tick-sched.c | 10 ++--------
>> 8 files changed, 15 insertions(+), 53 deletions(-)
>>
>> diff --git a/arch/powerpc/kernel/rtasd.c b/arch/powerpc/kernel/rtasd.c
>> index 5a2c049c1c61..567ed5a2f43a 100644
>> --- a/arch/powerpc/kernel/rtasd.c
>> +++ b/arch/powerpc/kernel/rtasd.c
>> @@ -49,7 +49,7 @@ static unsigned int rtas_error_log_buffer_max;
>> static unsigned int event_scan;
>> static unsigned int rtas_event_scan_rate;
>>
>> -static int full_rtas_msgs = 0;
>> +static bool full_rtas_msgs;
>>
>> /* Stop logging to nvram after first fatal error */
>> static int logging_enabled; /* Until we initialize everything,
>> @@ -592,11 +592,6 @@ __setup("surveillance=", surveillance_setup);
>>
>> static int __init rtasmsgs_setup(char *str)
>> {
>> - if (strcmp(str, "on") == 0)
>> - full_rtas_msgs = 1;
>> - else if (strcmp(str, "off") == 0)
>> - full_rtas_msgs = 0;
>> -
>> - return 1;
>> + return kstrtobool(str, 0, &full_rtas_msgs);
>> }
>> __setup("rtasmsgs=", rtasmsgs_setup);
>> diff --git a/arch/powerpc/platforms/pseries/hotplug-cpu.c b/arch/powerpc/platforms/pseries/hotplug-cpu.c
>> index 32274f72fe3f..b9787cae4108 100644
>> --- a/arch/powerpc/platforms/pseries/hotplug-cpu.c
>> +++ b/arch/powerpc/platforms/pseries/hotplug-cpu.c
>> @@ -47,20 +47,14 @@ static DEFINE_PER_CPU(enum cpu_state_vals, current_state) = CPU_STATE_OFFLINE;
>>
>> static enum cpu_state_vals default_offline_state = CPU_STATE_OFFLINE;
>>
>> -static int cede_offline_enabled __read_mostly = 1;
>> +static bool cede_offline_enabled __read_mostly = true;
>>
>> /*
>> * Enable/disable cede_offline when available.
>> */
>> static int __init setup_cede_offline(char *str)
>> {
>> - if (!strcmp(str, "off"))
>> - cede_offline_enabled = 0;
>> - else if (!strcmp(str, "on"))
>> - cede_offline_enabled = 1;
>> - else
>> - return 0;
>> - return 1;
>> + return kstrtobool(str, 0, &cede_offline_enabled);
>> }
>>
>> __setup("cede_offline=", setup_cede_offline);
>> diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
>> index 99f84ac31307..dff6ce1b84b2 100644
>> --- a/arch/s390/kernel/time.c
>> +++ b/arch/s390/kernel/time.c
>> @@ -1433,7 +1433,7 @@ device_initcall(etr_init_sysfs);
>> /*
>> * Server Time Protocol (STP) code.
>> */
>> -static int stp_online;
>> +static bool stp_online;
>> static struct stp_sstpi stp_info;
>> static void *stp_page;
>>
>> @@ -1444,11 +1444,7 @@ static struct timer_list stp_timer;
>>
>> static int __init early_parse_stp(char *p)
>> {
>> - if (strncmp(p, "off", 3) == 0)
>> - stp_online = 0;
>> - else if (strncmp(p, "on", 2) == 0)
>> - stp_online = 1;
>> - return 0;
>> + return kstrtobool(p, 0, &stp_online);
>> }
>> early_param("stp", early_parse_stp);
>>
>> diff --git a/arch/s390/kernel/topology.c b/arch/s390/kernel/topology.c
>> index 40b8102fdadb..5d8a80651f61 100644
>> --- a/arch/s390/kernel/topology.c
>> +++ b/arch/s390/kernel/topology.c
>> @@ -37,7 +37,7 @@ static void set_topology_timer(void);
>> static void topology_work_fn(struct work_struct *work);
>> static struct sysinfo_15_1_x *tl_info;
>>
>> -static int topology_enabled = 1;
>> +static bool topology_enabled = true;
>> static DECLARE_WORK(topology_work, topology_work_fn);
>>
>> /*
>> @@ -444,10 +444,7 @@ static const struct cpumask *cpu_book_mask(int cpu)
>>
>> static int __init early_parse_topology(char *p)
>> {
>> - if (strncmp(p, "off", 3))
>> - return 0;
>> - topology_enabled = 0;
>> - return 0;
>> + return kstrtobool(p, 0, &topology_enabled);
>> }
>> early_param("topology", early_parse_topology);
>>
>> diff --git a/arch/x86/kernel/aperture_64.c b/arch/x86/kernel/aperture_64.c
>> index 6e85f713641d..6b423754083a 100644
>> --- a/arch/x86/kernel/aperture_64.c
>> +++ b/arch/x86/kernel/aperture_64.c
>> @@ -227,19 +227,11 @@ static u32 __init search_agp_bridge(u32 *order, int *valid_agp)
>> return 0;
>> }
>>
>> -static int gart_fix_e820 __initdata = 1;
>> +static bool gart_fix_e820 __initdata = true;
>>
>> static int __init parse_gart_mem(char *p)
>> {
>> - if (!p)
>> - return -EINVAL;
>> -
>> - if (!strncmp(p, "off", 3))
>> - gart_fix_e820 = 0;
>> - else if (!strncmp(p, "on", 2))
>> - gart_fix_e820 = 1;
>> -
>> - return 0;
>> + return kstrtobool(p, 0, &gart_fix_e820);
>> }
>> early_param("gart_fix_e820", parse_gart_mem);
>>
>> diff --git a/include/linux/tick.h b/include/linux/tick.h
>> index 97fd4e543846..0ecdf0e248f4 100644
>> --- a/include/linux/tick.h
>> +++ b/include/linux/tick.h
>> @@ -98,7 +98,7 @@ static inline void tick_broadcast_exit(void)
>> }
>>
>> #ifdef CONFIG_NO_HZ_COMMON
>> -extern int tick_nohz_enabled;
>> +extern bool tick_nohz_enabled;
>> extern int tick_nohz_tick_stopped(void);
>> extern void tick_nohz_idle_enter(void);
>> extern void tick_nohz_idle_exit(void);
>> diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
>> index 435b8850dd80..456f066148d5 100644
>> --- a/kernel/time/hrtimer.c
>> +++ b/kernel/time/hrtimer.c
>> @@ -515,7 +515,7 @@ static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
>> /*
>> * High resolution timer enabled ?
>> */
>> -static int hrtimer_hres_enabled __read_mostly = 1;
>> +static bool hrtimer_hres_enabled __read_mostly = true;
>> unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
>> EXPORT_SYMBOL_GPL(hrtimer_resolution);
>>
>> @@ -524,13 +524,7 @@ EXPORT_SYMBOL_GPL(hrtimer_resolution);
>> */
>> static int __init setup_hrtimer_hres(char *str)
>> {
>> - if (!strcmp(str, "off"))
>> - hrtimer_hres_enabled = 0;
>> - else if (!strcmp(str, "on"))
>> - hrtimer_hres_enabled = 1;
>> - else
>> - return 0;
>> - return 1;
>> + return kstrtobool(str, 0, &hrtimer_hres_enabled);
>> }
>>
>> __setup("highres=", setup_hrtimer_hres);
>> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
>> index 9d7a053545f5..b57f822c2069 100644
>> --- a/kernel/time/tick-sched.c
>> +++ b/kernel/time/tick-sched.c
>> @@ -387,20 +387,14 @@ void __init tick_nohz_init(void)
>> /*
>> * NO HZ enabled ?
>> */
>> -int tick_nohz_enabled __read_mostly = 1;
>> +bool tick_nohz_enabled __read_mostly = true;
>> unsigned long tick_nohz_active __read_mostly;
>> /*
>> * Enable / Disable tickless mode
>> */
>> static int __init setup_tick_nohz(char *str)
>> {
>> - if (!strcmp(str, "off"))
>> - tick_nohz_enabled = 0;
>> - else if (!strcmp(str, "on"))
>> - tick_nohz_enabled = 1;
>> - else
>> - return 0;
>> - return 1;
>> + return kstrtobool(str, 0, &tick_nohz_enabled);
>> }
>>
>> __setup("nohz=", setup_tick_nohz);
>> --
>> 2.6.3
>>
>
>
>
> --
> With Best Regards,
> Andy Shevchenko

--
Kees Cook
Chrome OS & Brillo Security

Next message: Rusty Russell: "[PATCH 2/3] module: wrapper for symbol name."
Previous message: Rasmus Villemoes: "Re: [PATCH v2] vsprintf: automatic parameters for %pIS via 'a'"
In reply to: Andy Shevchenko: "Re: [PATCH v2 4/4] param: convert some "on"/"off" users to strtobool"
Next in thread: Kees Cook: "Re: [PATCH v2 4/4] param: convert some "on"/"off" users to strtobool"
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