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