platform/x86: ISST: Check for admin capability for write commands

In some SST deployments, administrators want to allow reading SST
capabilities for non-root users. This can be achieved by changing file
permissions for "/dev/isst_interface", but they still want to prevent
any changes to the SST configuration by non-root users.

This capability was available before for non-TPMI SST. Extend the same
capability for TPMI SST by adding a check for CAP_SYS_ADMIN for all
write commands.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Link: https://patch.msgid.link/20260107060729.1634420-1-srinivas.pandruvada@linux.intel.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

diff --git a/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c b/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
index 13b11c3a2ec4ea590e00ac55241f7f0d64a984b3..f71d7df03f3587ef8c38862f74ef80cbed8259af 100644 (file)
--- a/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
+++ b/drivers/platform/x86/intel/speed_select_if/isst_tpmi_core.c
@@ -612,7 +612,7 @@ static long isst_if_core_power_state(void __user *argp)
                return -EINVAL;
 
        if (core_power.get_set) {
-               if (power_domain_info->write_blocked)
+               if (power_domain_info->write_blocked || !capable(CAP_SYS_ADMIN))
                        return -EPERM;
 
                _write_cp_info("cp_enable", core_power.enable, SST_CP_CONTROL_OFFSET,
@@ -659,7 +659,7 @@ static long isst_if_clos_param(void __user *argp)
                return -EINVAL;
 
        if (clos_param.get_set) {
-               if (power_domain_info->write_blocked)
+               if (power_domain_info->write_blocked || !capable(CAP_SYS_ADMIN))
                        return -EPERM;
 
                _write_cp_info("clos.min_freq", clos_param.min_freq_mhz,
@@ -751,7 +751,8 @@ static long isst_if_clos_assoc(void __user *argp)
 
                power_domain_info = &sst_inst->power_domain_info[part][punit_id];
 
-               if (assoc_cmds.get_set && power_domain_info->write_blocked)
+               if (assoc_cmds.get_set && (power_domain_info->write_blocked ||
+                                          !capable(CAP_SYS_ADMIN)))
                        return -EPERM;
 
                offset = SST_CLOS_ASSOC_0_OFFSET +
@@ -928,7 +929,7 @@ static int isst_if_set_perf_level(void __user *argp)
        if (!power_domain_info)
                return -EINVAL;
 
-       if (power_domain_info->write_blocked)
+       if (power_domain_info->write_blocked || !capable(CAP_SYS_ADMIN))
                return -EPERM;
 
        if (!(power_domain_info->pp_header.allowed_level_mask & BIT(perf_level.level)))
@@ -988,7 +989,7 @@ static int isst_if_set_perf_feature(void __user *argp)
        if (!power_domain_info)
                return -EINVAL;
 
-       if (power_domain_info->write_blocked)
+       if (power_domain_info->write_blocked || !capable(CAP_SYS_ADMIN))
                return -EPERM;
 
        _write_pp_info("perf_feature", perf_feature.feature, SST_PP_CONTROL_OFFSET,