hwmon: (dell-smm) Restrict fan control and serial number to CAP_SYS_ADMIN by default
For security reasons ordinary user must not be able to control fan speed via /proc/i8k by default. Some malicious software running under "nobody" user could be able to turn fan off and cause HW problems. So this patch changes default value of "restricted" parameter to 1. Also restrict reading of DMI_PRODUCT_SERIAL from /proc/i8k via "restricted" parameter. It is because non root user cannot read DMI_PRODUCT_SERIAL from sysfs file /sys/class/dmi/id/product_serial. Old non secure behaviour of file /proc/i8k can be achieved by loading this module with "restricted" parameter set to 0. Note that this patch has effects only for kernels compiled with CONFIG_I8K and only for file /proc/i8k. Hwmon interface provided by this driver was not changed and root access for setting fan speed was needed also before. Reported-by: Mario Limonciello <Mario_Limonciello@dell.com> Signed-off-by: Pali Rohár <pali.rohar@gmail.com> Cc: stable@vger.kernel.org # will need backport Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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