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"); 134