1 /* 2 * Copyright 2018 Google Inc. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include "cable.hpp" 18 19 #include "main.hpp" 20 21 #include <cstdint> 22 #include <cstring> 23 #include <filesystem> 24 #include <fstream> 25 #include <sstream> 26 #include <string> 27 #include <system_error> 28 29 namespace google 30 { 31 namespace ipmi 32 { 33 namespace fs = std::filesystem; 34 35 struct CableRequest 36 { 37 uint8_t subcommand; 38 uint8_t if_name_len; 39 uint8_t if_name[0]; 40 } __attribute__((packed)); 41 42 struct CableReply 43 { 44 uint8_t subcommand; 45 uint8_t value; 46 } __attribute__((packed)); 47 48 ipmi_ret_t CableCheck(const uint8_t* reqBuf, uint8_t* replyBuf, size_t* dataLen) 49 { 50 // There is an IPMI LAN channel statistics command which could be used for 51 // this type of check, however, we're not able to wait for the OpenBMC 52 // implementation to stabilize related to the network management. 53 // 54 // There is a link status file, but it is "unknown" to start with... 55 // The path we're checking: /sys/class/net/eth1/statistics/rx_packets 56 57 // This command is expecting: [0x00][len][if_name] 58 if ((*dataLen) < sizeof(struct CableRequest) + sizeof(uint8_t)) 59 { 60 std::fprintf(stderr, "Invalid command length: %u\n", 61 static_cast<uint32_t>(*dataLen)); 62 return IPMI_CC_REQ_DATA_LEN_INVALID; 63 } 64 65 const auto request = 66 reinterpret_cast<const struct CableRequest*>(&reqBuf[0]); 67 68 // Sanity check the object contents. 69 if (request->if_name_len == 0) 70 { 71 std::fprintf(stderr, "Invalid string length: %d\n", 72 request->if_name_len); 73 return IPMI_CC_REQ_DATA_LEN_INVALID; 74 } 75 76 // Verify the request buffer contains the object and the string. 77 if ((*dataLen) < (sizeof(struct CableRequest) + request->if_name_len)) 78 { 79 std::fprintf(stderr, "*dataLen too small: %u\n", 80 static_cast<uint32_t>(*dataLen)); 81 return IPMI_CC_REQ_DATA_LEN_INVALID; 82 } 83 84 // Maximum length one can specify, plus null terminator. 85 char nameBuf[256] = {}; 86 std::ostringstream opath; 87 88 // Copy the string out of the request buffer. 89 std::memcpy(&nameBuf[0], request->if_name, request->if_name_len); 90 std::string name = nameBuf; 91 92 // Minor sanity & security check (of course, I'm less certain if unicode 93 // comes into play here. 94 // 95 // Basically you can't easily inject ../ or /../ into the path below. 96 if (name.find("/") != std::string::npos) 97 { 98 std::fprintf(stderr, "Invalid or illegal name: '%s'\n", nameBuf); 99 return IPMI_CC_INVALID_FIELD_REQUEST; 100 } 101 102 opath << "/sys/class/net/" << name << "/statistics/rx_packets"; 103 std::string path = opath.str(); 104 105 std::error_code ec; 106 if (!fs::exists(path, ec)) 107 { 108 std::fprintf(stderr, "Path: '%s' doesn't exist.\n", path.c_str()); 109 return IPMI_CC_INVALID_FIELD_REQUEST; 110 } 111 // We're uninterested in the state of ec. 112 113 // Read the file and check the result. 114 int64_t count = 0; 115 std::ifstream ifs; 116 ifs.exceptions(std::ifstream::failbit); 117 try 118 { 119 ifs.open(path); 120 ifs >> count; 121 } 122 catch (std::ios_base::failure& fail) 123 { 124 return IPMI_CC_UNSPECIFIED_ERROR; 125 } 126 127 struct CableReply reply; 128 reply.subcommand = SysCableCheck; 129 130 // If we have received packets then there is a cable present. 131 reply.value = (count > 0) ? 1 : 0; 132 133 // Return the subcommand and the result. 134 std::memcpy(&replyBuf[0], &reply, sizeof(struct CableReply)); 135 (*dataLen) = sizeof(struct CableReply); 136 137 return IPMI_CC_OK; 138 } 139 140 } // namespace ipmi 141 } // namespace google 142