On Mon, Mar 12, 2018 at 04:15:41PM -0400, Waiman Long wrote:
> Even with clamped sysctl parameters, it is still not that straight
> forward to figure out the exact range of those parameters. One may
> try to write extreme parameter values to see if they get clamped.
> To make it easier, a warning with the expected range will now be
> printed into the kernel ring buffer when a clamped sysctl parameter
> receives an out of range value.
>
> The pr_warn_ratelimited() macro is used to limit the number of warning
> messages that can be printed within a given period of time.
>
> Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
> ---
> kernel/sysctl.c | 48 ++++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 40 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 3d65f41..14aca92 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -2505,6 +2505,7 @@ static int proc_dointvec_minmax_sysadmin(struct ctl_table *table, int write,
> * @min: pointer to minimum allowable value
> * @max: pointer to maximum allowable value
> * @flags: pointer to flags
> + * @name: sysctl parameter name
> *
> * The do_proc_dointvec_minmax_conv_param structure provides the
> * minimum and maximum values for doing range checking for those sysctl
> @@ -2514,31 +2515,48 @@ struct do_proc_dointvec_minmax_conv_param {
> int *min;
> int *max;
> unsigned int *flags;
> + const char *name;
> };
>
> +#ifdef pr_fmt
> +#undef pr_fmt
> +#endif
> +#define pr_fmt(fmt) "sysctl: " fmt
No. This needs to be defined at the top of the file, please look
at other uses on kernel/*.c and just use:
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
The filename already provides the name we want.
> +
> static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp,
> int *valp,
> int write, void *data)
> {
> struct do_proc_dointvec_minmax_conv_param *param = data;
> +
> if (write) {
> int val = *negp ? -*lvalp : *lvalp;
> + bool clamped = false;
> bool clamp = param->flags &&
> (*param->flags & CTL_FLAGS_CLAMP_RANGE);
>
> if (param->min && *param->min > val) {
> - if (clamp)
> + if (clamp) {
> val = *param->min;
> - else
> + clamped = true;
> + } else {
> return -EINVAL;
> + }
> }
> if (param->max && *param->max < val) {
> - if (clamp)
> + if (clamp) {
> val = *param->max;
> - else
> + clamped = true;
> + } else {
> return -EINVAL;
> + }
> }
> *valp = val;
> + if (clamped && param->name)
> + pr_warn_ratelimited("\"%s\" was set out of range [%d, %d], clamped to %d.\n",
> + param->name,
> + param->min ? *param->min : -INT_MAX,
> + param->max ? *param->max : INT_MAX, val);
We already warn here but I see you also add yet-another warning for the driver....
Luis
