[net-next 03/10] devlink: Add helper function for safely copy string param

Saeed Mahameed
2018-08-01T23:48:53Z

From: Moshe Shemesh <moshe@mellanox.com>

Devlink string param buffer is allocated at the size of
DEVLINK_PARAM_MAX_STRING_VALUE. Add helper function which makes sure
this size is not exceeded.
Renamed DEVLINK_PARAM_MAX_STRING_VALUE to
__DEVLINK_PARAM_MAX_STRING_VALUE to emphasize that it should be used by
devlink only. The driver should use the helper function instead to
verify it doesn't exceed the allowed length.

Signed-off-by: Moshe Shemesh <moshe@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
---
include/net/devlink.h | 12 ++++++++++--
net/core/devlink.c | 19 ++++++++++++++++++-
2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/include/net/devlink.h b/include/net/devlink.h
index b0e17c025fdc..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;
- char vstr[DEVLINK_PARAM_MAX_STRING_VALUE];
+ 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 99ad53e8297f..367564099357 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -3012,7 +3012,7 @@ devlink_param_value_get_from_info(const struct devlink_param *param,
break;
case DEVLINK_PARAM_TYPE_STRING:
if (nla_len(info->attrs[DEVLINK_ATTR_PARAM_VALUE_DATA]) >
- DEVLINK_PARAM_MAX_STRING_VALUE)
+ __DEVLINK_PARAM_MAX_STRING_VALUE)
return -EINVAL;
strcpy(value->vstr,
nla_data(info->attrs[DEVLINK_ATTR_PARAM_VALUE_DATA]));
@@ -4614,6 +4614,23 @@ 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
*
--
2.17.0