drivers/staging/greybus/log.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Greybus driver for the log protocol
   4  *
   5  * Copyright 2016 Google Inc.
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/module.h>
   9 #include <linux/slab.h>
  10 #include <linux/sizes.h>
  11 #include <linux/uaccess.h>
  12 #include <linux/greybus.h>
  13
  14 struct gb_log {
  15         struct gb_connection *connection;
  16 };
  17
  18 static int gb_log_request_handler(struct gb_operation *op)
  19 {
  20         struct gb_connection *connection = op->connection;
  21         struct device *dev = &connection->bundle->dev;
  22         struct gb_log_send_log_request *receive;
  23         u16 len;
  24
  25         if (op->type != GB_LOG_TYPE_SEND_LOG) {
  26                 dev_err(dev, "unknown request type 0x%02x\n", op->type);
  27                 return -EINVAL;
  28         }
  29
  30         /* Verify size of payload */
  31         if (op->request->payload_size < sizeof(*receive)) {
  32                 dev_err(dev, "log request too small (%zu < %zu)\n",
  33                         op->request->payload_size, sizeof(*receive));
  34                 return -EINVAL;
  35         }
  36         receive = op->request->payload;
  37         len = le16_to_cpu(receive->len);
  38         if (len != (op->request->payload_size - sizeof(*receive))) {
  39                 dev_err(dev, "log request wrong size %d vs %zu\n", len,
  40                         (op->request->payload_size - sizeof(*receive)));
  41                 return -EINVAL;
  42         }
  43         if (len == 0) {
  44                 dev_err(dev, "log request of 0 bytes?\n");
  45                 return -EINVAL;
  46         }
  47
  48         if (len > GB_LOG_MAX_LEN) {
  49                 dev_err(dev, "log request too big: %d\n", len);
  50                 return -EINVAL;
  51         }
  52
  53         /* Ensure the buffer is 0 terminated */
  54         receive->msg[len - 1] = '\0';
  55
  56         /*
  57          * Print with dev_dbg() so that it can be easily turned off using
  58          * dynamic debugging (and prevent any DoS)
  59          */
  60         dev_dbg(dev, "%s", receive->msg);
  61
  62         return 0;
  63 }
  64
  65 static int gb_log_probe(struct gb_bundle *bundle,
  66                         const struct greybus_bundle_id *id)
  67 {
  68         struct greybus_descriptor_cport *cport_desc;
  69         struct gb_connection *connection;
  70         struct gb_log *log;
  71         int retval;
  72
  73         if (bundle->num_cports != 1)
  74                 return -ENODEV;
  75
  76         cport_desc = &bundle->cport_desc[0];
  77         if (cport_desc->protocol_id != GREYBUS_PROTOCOL_LOG)
  78                 return -ENODEV;
  79
  80         log = kzalloc(sizeof(*log), GFP_KERNEL);
  81         if (!log)
  82                 return -ENOMEM;
  83
  84         connection = gb_connection_create(bundle, le16_to_cpu(cport_desc->id),
  85                                           gb_log_request_handler);
  86         if (IS_ERR(connection)) {
  87                 retval = PTR_ERR(connection);
  88                 goto error_free;
  89         }
  90
  91         log->connection = connection;
  92         greybus_set_drvdata(bundle, log);
  93
  94         retval = gb_connection_enable(connection);
  95         if (retval)
  96                 goto error_connection_destroy;
  97
  98         return 0;
  99
 100 error_connection_destroy:
 101         gb_connection_destroy(connection);
 102 error_free:
 103         kfree(log);
 104         return retval;
 105 }
 106
 107 static void gb_log_disconnect(struct gb_bundle *bundle)
 108 {
 109         struct gb_log *log = greybus_get_drvdata(bundle);
 110         struct gb_connection *connection = log->connection;
 111
 112         gb_connection_disable(connection);
 113         gb_connection_destroy(connection);
 114
 115         kfree(log);
 116 }
 117
 118 static const struct greybus_bundle_id gb_log_id_table[] = {
 119         { GREYBUS_DEVICE_CLASS(GREYBUS_CLASS_LOG) },
 120         { }
 121 };
 122 MODULE_DEVICE_TABLE(greybus, gb_log_id_table);
 123
 124 static struct greybus_driver gb_log_driver = {
 125         .name           = "log",
 126         .probe          = gb_log_probe,
 127         .disconnect     = gb_log_disconnect,
 128         .id_table       = gb_log_id_table,
 129 };
 130 module_greybus_driver(gb_log_driver);
 131
 132 MODULE_LICENSE("GPL v2");