Merge branch 'devlink-param-type-string-fixes'

Moshe Shemesh says:

====================
devlink param type string fixes

This patchset fixes devlink param infrastructure for string param type.

The devlink param infrastructure doesn't handle copying the string data
correctly.  The first two patches fix it and the third patch adds helper
function to safely copy string value without exceeding
DEVLINK_PARAM_MAX_STRING_VALUE.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 47 insertions, 8 deletions

diff --git a/include/net/devlink.h b/include/net/devlink.h
index b9b89d6604d4..99efc156a309 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -298,7 +298,7 @@ struct devlink_resource {
 
 #define DEVLINK_RESOURCE_ID_PARENT_TOP 0
 
-#define DEVLINK_PARAM_MAX_STRING_VALUE 32
+#define __DEVLINK_PARAM_MAX_STRING_VALUE 32
 enum devlink_param_type {
         DEVLINK_PARAM_TYPE_U8,
         DEVLINK_PARAM_TYPE_U16,
@@ -311,7 +311,7 @@ union devlink_param_value {
         u8 vu8;
         u16 vu16;
         u32 vu32;
-        const char *vstr;
+        char vstr[__DEVLINK_PARAM_MAX_STRING_VALUE];
         bool vbool;
 };
 
@@ -553,6 +553,8 @@ int devlink_param_driverinit_value_get(struct devlink *devlink, u32 param_id,
 int devlink_param_driverinit_value_set(struct devlink *devlink, u32 param_id,
                                        union devlink_param_value init_val);
 void devlink_param_value_changed(struct devlink *devlink, u32 param_id);
+void devlink_param_value_str_fill(union devlink_param_value *dst_val,
+                                  const char *src);
 struct devlink_region *devlink_region_create(struct devlink *devlink,
                                              const char *region_name,
                                              u32 region_max_snapshots,
@@ -789,6 +791,12 @@ devlink_param_value_changed(struct devlink *devlink, u32 param_id)
 {
 }
 
+static inline void
+devlink_param_value_str_fill(union devlink_param_value *dst_val,
+                             const char *src)
+{
+}
+
 static inline struct devlink_region *
 devlink_region_create(struct devlink *devlink,
                       const char *region_name,
diff --git a/net/core/devlink.c b/net/core/devlink.c
index 8c0ed225e280..6bc42933be4a 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -2995,6 +2995,8 @@ devlink_param_value_get_from_info(const struct devlink_param *param,
                                   struct genl_info *info,
                                   union devlink_param_value *value)
 {
+        int len;
+
         if (param->type != DEVLINK_PARAM_TYPE_BOOL &&
             !info->attrs[DEVLINK_ATTR_PARAM_VALUE_DATA])
                 return -EINVAL;
@@ -3010,10 +3012,13 @@ devlink_param_value_get_from_info(const struct devlink_param *param,
                 value->vu32 = nla_get_u32(info->attrs[DEVLINK_ATTR_PARAM_VALUE_DATA]);
                 break;
         case DEVLINK_PARAM_TYPE_STRING:
-                if (nla_len(info->attrs[DEVLINK_ATTR_PARAM_VALUE_DATA]) >
-                    DEVLINK_PARAM_MAX_STRING_VALUE)
+                len = strnlen(nla_data(info->attrs[DEVLINK_ATTR_PARAM_VALUE_DATA]),
+                              nla_len(info->attrs[DEVLINK_ATTR_PARAM_VALUE_DATA]));
+                if (len == nla_len(info->attrs[DEVLINK_ATTR_PARAM_VALUE_DATA]) ||
+                    len >= __DEVLINK_PARAM_MAX_STRING_VALUE)
                         return -EINVAL;
-                value->vstr = nla_data(info->attrs[DEVLINK_ATTR_PARAM_VALUE_DATA]);
+                strcpy(value->vstr,
+                       nla_data(info->attrs[DEVLINK_ATTR_PARAM_VALUE_DATA]));
                 break;
         case DEVLINK_PARAM_TYPE_BOOL:
                 value->vbool = info->attrs[DEVLINK_ATTR_PARAM_VALUE_DATA] ?
@@ -3100,7 +3105,10 @@ static int devlink_nl_cmd_param_set_doit(struct sk_buff *skb,
                 return -EOPNOTSUPP;
 
         if (cmode == DEVLINK_PARAM_CMODE_DRIVERINIT) {
-                param_item->driverinit_value = value;
+                if (param->type == DEVLINK_PARAM_TYPE_STRING)
+                        strcpy(param_item->driverinit_value.vstr, value.vstr);
+                else
+                        param_item->driverinit_value = value;
                 param_item->driverinit_value_valid = true;
         } else {
                 if (!param->set)
@@ -4540,7 +4548,10 @@ int devlink_param_driverinit_value_get(struct devlink *devlink, u32 param_id,
                                               DEVLINK_PARAM_CMODE_DRIVERINIT))
                 return -EOPNOTSUPP;
 
-        *init_val = param_item->driverinit_value;
+        if (param_item->param->type == DEVLINK_PARAM_TYPE_STRING)
+                strcpy(init_val->vstr, param_item->driverinit_value.vstr);
+        else
+                *init_val = param_item->driverinit_value;
 
         return 0;
 }
@@ -4571,7 +4582,10 @@ int devlink_param_driverinit_value_set(struct devlink *devlink, u32 param_id,
                                               DEVLINK_PARAM_CMODE_DRIVERINIT))
                 return -EOPNOTSUPP;
 
-        param_item->driverinit_value = init_val;
+        if (param_item->param->type == DEVLINK_PARAM_TYPE_STRING)
+                strcpy(param_item->driverinit_value.vstr, init_val.vstr);
+        else
+                param_item->driverinit_value = init_val;
         param_item->driverinit_value_valid = true;
 
         devlink_param_notify(devlink, param_item, DEVLINK_CMD_PARAM_NEW);
@@ -4604,6 +4618,23 @@ void devlink_param_value_changed(struct devlink *devlink, u32 param_id)
 EXPORT_SYMBOL_GPL(devlink_param_value_changed);
 
 /**
+ *      devlink_param_value_str_fill - Safely fill-up the string preventing
+ *                                     from overflow of the preallocated buffer
+ *
+ *      @dst_val: destination devlink_param_value
+ *      @src: source buffer
+ */
+void devlink_param_value_str_fill(union devlink_param_value *dst_val,
+                                  const char *src)
+{
+        size_t len;
+
+        len = strlcpy(dst_val->vstr, src, __DEVLINK_PARAM_MAX_STRING_VALUE);
+        WARN_ON(len >= __DEVLINK_PARAM_MAX_STRING_VALUE);
+}
+EXPORT_SYMBOL_GPL(devlink_param_value_str_fill);
+
+/**
  *      devlink_region_create - create a new address region
  *
  *      @devlink: devlink