libnvdimm: Fix security issue with DSM IOCTL.

Code attempts to prevent certain IOCTL DSM from being called
when device is opened read only.  This security feature can
be trivially overcome by changing the size portion of the
ioctl_command which isn't used.

Check only the _IOC_NR (i.e. the command).

Cc: <stable@vger.kernel.org>
Signed-off-by: Jerry Hoemann <jerry.hoemann@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/nvdimm/bus.c b/drivers/nvdimm/bus.c
index f85227a5ee2886f3b5494f58689fc56c2d6b0b9b..2e9ac22595ec4e9298d744a0e368039c9d6eac8f 100644 (file)
--- a/drivers/nvdimm/bus.c
+++ b/drivers/nvdimm/bus.c
@@ -547,10 +547,10 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
 
        /* fail write commands (when read-only) */
        if (read_only)
-               switch (ioctl_cmd) {
-               case ND_IOCTL_VENDOR:
-               case ND_IOCTL_SET_CONFIG_DATA:
-               case ND_IOCTL_ARS_START:
+               switch (cmd) {
+               case ND_CMD_VENDOR:
+               case ND_CMD_SET_CONFIG_DATA:
+               case ND_CMD_ARS_START:
                        dev_dbg(&nvdimm_bus->dev, "'%s' command while read-only.\n",
                                        nvdimm ? nvdimm_cmd_name(cmd)
                                        : nvdimm_bus_cmd_name(cmd));