USB: Add a serial number parameter to g_file_storage module

This patch add a serial number parameter to the g_file_storage
module. There's validity checks against the string passed to comply
with the specs.

Signed-off-by: Yann Cantin <yann.cantin@laposte.net>
Cc: Michał Nazarewicz <m.nazarewicz@samsung.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 58 insertions, 11 deletions

diff --git a/drivers/usb/gadget/file_storage.c b/drivers/usb/gadget/file_storage.c
index b49d86e3e45b..2b6d3649d02c 100644
--- a/drivers/usb/gadget/file_storage.c
+++ b/drivers/usb/gadget/file_storage.c
@@ -56,7 +56,7 @@
  * following protocols: RBC (0x01), ATAPI or SFF-8020i (0x02), QIC-157 (0c03),
  * UFI (0x04), SFF-8070i (0x05), and transparent SCSI (0x06), selected by
  * the optional "protocol" module parameter.  In addition, the default
- * Vendor ID, Product ID, and release number can be overridden.
+ * Vendor ID, Product ID, release number and serial number can be overridden.
  *
  * There is support for multiple logical units (LUNs), each of which has
  * its own backing file.  The number of LUNs can be set using the optional
@@ -106,6 +106,7 @@
  *      vendor=0xVVVV           Default 0x0525 (NetChip), USB Vendor ID
  *      product=0xPPPP          Default 0xa4a5 (FSG), USB Product ID
  *      release=0xRRRR          Override the USB release number (bcdDevice)
+ *      serial=HHHH...          Override serial number (string of hex chars)
  *      buflen=N                Default N=16384, buffer size used (will be
  *                                      rounded down to a multiple of
  *                                      PAGE_CACHE_SIZE)
@@ -270,6 +271,8 @@
 
 #define DRIVER_DESC             "File-backed Storage Gadget"
 #define DRIVER_NAME             "g_file_storage"
+/* DRIVER_VERSION must be at least 6 characters long, as it is used
+ * to generate a fallback serial number. */
 #define DRIVER_VERSION          "20 November 2008"
 
 static       char fsg_string_manufacturer[64];
@@ -314,6 +317,7 @@ static struct {
         unsigned short  vendor;
         unsigned short  product;
         unsigned short  release;
+        char            *serial_parm;
         unsigned int    buflen;
 
         int             transport_type;
@@ -374,6 +378,9 @@ MODULE_PARM_DESC(product, "USB Product ID");
 module_param_named(release, mod_data.release, ushort, S_IRUGO);
 MODULE_PARM_DESC(release, "USB release number");
 
+module_param_named(serial, mod_data.serial_parm, charp, S_IRUGO);
+MODULE_PARM_DESC(serial, "USB serial number");
+
 module_param_named(buflen, mod_data.buflen, uint, S_IRUGO);
 MODULE_PARM_DESC(buflen, "I/O buffer size");
 
@@ -3197,6 +3204,7 @@ static int __init check_parameters(struct fsg_dev *fsg)
 {
         int     prot;
         int     gcnum;
+        int     i;
 
         /* Store the default values */
         mod_data.transport_type = USB_PR_BULK;
@@ -3272,6 +3280,55 @@ static int __init check_parameters(struct fsg_dev *fsg)
                 ERROR(fsg, "invalid buflen\n");
                 return -ETOOSMALL;
         }
+
+        /* Serial string handling.
+         * On a real device, the serial string would be loaded
+         * from permanent storage. */
+        if (mod_data.serial_parm) {
+                const char *ch;
+                unsigned len = 0;
+
+                /* Sanity check :
+                 * The CB[I] specification limits the serial string to
+                 * 12 uppercase hexadecimal characters.
+                 * BBB need at least 12 uppercase hexadecimal characters,
+                 * with a maximum of 126. */
+                for (ch = mod_data.serial_parm; *ch; ++ch) {
+                        ++len;
+                        if ((*ch < '0' || *ch > '9') &&
+                            (*ch < 'A' || *ch > 'F')) { /* not uppercase hex */
+                                WARNING(fsg,
+                                        "Invalid serial string character: %c; "
+                                        "Failing back to default\n",
+                                        *ch);
+                                goto fill_serial;
+                        }
+                }
+                if (len > 126 ||
+                    (mod_data.transport_type == USB_PR_BULK && len < 12) ||
+                    (mod_data.transport_type != USB_PR_BULK && len > 12)) {
+                        WARNING(fsg,
+                                "Invalid serial string length; "
+                                "Failing back to default\n");
+                        goto fill_serial;
+                }
+                fsg_strings[FSG_STRING_SERIAL - 1].s = mod_data.serial_parm;
+        } else {
+fill_serial:
+                /* Serial number not specified or invalid, make our own.
+                 * We just encode it from the driver version string,
+                 * 12 characters to comply with both CB[I] and BBB spec.
+                 * Warning : Two devices running the same kernel will have
+                 * the same fallback serial number. */
+                for (i = 0; i < 12; i += 2) {
+                        unsigned char   c = DRIVER_VERSION[i / 2];
+
+                        if (!c)
+                                break;
+                        sprintf(&fsg_string_serial[i], "%02X", c);
+                }
+        }
+
 #endif /* CONFIG_USB_FILE_STORAGE_TEST */
 
         return 0;
@@ -3447,16 +3504,6 @@ static int __init fsg_bind(struct usb_gadget *gadget)
                         init_utsname()->sysname, init_utsname()->release,
                         gadget->name);
 
-        /* On a real device, serial[] would be loaded from permanent
-         * storage.  We just encode it from the driver version string. */
-        for (i = 0; i < sizeof fsg_string_serial - 2; i += 2) {
-                unsigned char           c = DRIVER_VERSION[i / 2];
-
-                if (!c)
-                        break;
-                sprintf(&fsg_string_serial[i], "%02X", c);
-        }
-
         fsg->thread_task = kthread_create(fsg_main_thread, fsg,
                         "file-storage-gadget");
         if (IS_ERR(fsg->thread_task)) {