1# BMC Certificate management 2 3Certificate management allows to replace the existing certificate and private 4key file with another (possibly certification Authority (CA) signed) 5certificate and private key file. Certificate management allows the user to 6install both the server and client certificates. The REST interface allows to 7update the certificate, using an unencrypted certificate and private key file 8in .pem format, which includes both private key and signed certificate. 9 10### Signed Certificate upload Design flow(Pre-generated): 11 12- The REST Server copies the certificate and private key file to a temporary 13 location. 14- REST server should map the URI to the target DBus application (Certs) object. 15 The recommendation for the D-Bus application implementing certificate D-Bus 16 objects is to use the same path structure as the REST endpoint. 17 e.g.: 18 - The URI /xyz/openbmc_project/certs/server/https maps to instance 19 of the certificate application handling Https server certificate. 20 - The URI /xyz/openbmc_project/certs/client/ldap maps to instance 21 of the certificate application handling LDAP client certificate. 22 - The URI /xyz/openbmc_project/certs/authority/ldap maps to instance 23 of the certificate application handling Certificate Autohority 24 certificates. 25- REST server should call the install method of the certificate application 26 instance. 27- Certificate manager application also implements d-bus object 28 xyz.openbmc_project.Certs.Manager. This includes the collection of 29 "certificates specific d-bus objects" installed in the system. This d-bus 30 provide option to view the certificate on PEM format and delete the same. 31 Refer https://en.wikipedia.org/wiki/Privacy-Enhanced_Mail for details. 32- Applications should subscribe the xyz.openbmc_project.Certs.Manager 33 to see any new certificate is uploaded or change in the existing 34 certificates. 35- Certificate manager scope is limited to manage the certificate and impacted 36 application is responsible for application specific changes. 37- In case of delete action, certificate manager creates a new self signed 38 certificate after successful delete (regards only server type certificates) 39 40### REST interface details: 41 42 ``` 43 url: /xyz/openbmc_project/certs/server/https 44 Description: Update https server signed certificate and the private key. 45 Method: PUT 46 47 url: /xyz/openbmc_project/certs/server/https/<cert_id> 48 Description: Delete https server signed certificate and the private key. 49 Method: DELETE 50 51 url: /xyz/openbmc_project/certs/client/ldap 52 Description: Update ldap client certificate and the private key. 53 Method: PUT 54 55 url: /xyz/openbmc_project/certs/client/ldap/<cert_id> 56 Description: Delete ldap client certificate and the private key. 57 Method: DELETE 58 59 Return codes 60 61 200 Success 62 400 Invalid certificate and private key file. 63 405 Method not supported. 64 500 Internal server error 65 66 ``` 67 68## CSR 69 70### User flow for generating and installing Certificates(CSR Based): 71 Certificate Signing Request [CSR](https://en.wikipedia.org/wiki/Certificate_signing_request) 72is a message sent from an applicant to a certitificate authority in order to 73apply for a digital identity certificate. This section provides the details of 74the CSR based certificate user flow. 75- The user performs the CSR/create interface 76 BMC creates new private key and CSR object which includes CSR information. 77- The user performs the CSR/export interface 78 Allows the user to export the CSR file which is part of newly created 79 CSR object. This can be provided to the CA to create SSL certificate. 80- The user perform the certificate upload on appropriate services. 81 Example: if trying to replace the HTTPS certificate for a Manager, 82 navigate to the Manager’s Certificate object upload interface. 83 The Upload method internally pairs the private key used in the first 84 step with the installed certificate. 85 86### Assumptions: 87- BMC updates the private key associated to CSR for any new CSR request. 88- BMC upload process automatically appends certificate file with system CSR 89 private key, for the service which requirs certificate and key. 90- CSR based Certificate validation is alway's based on private key in the system. 91 92### CSR Request 93- CSR requests initiated through D-Bus are time-consuming and might result 94 D-Bus time-out error. 95- To overcome the time-out error, parent process is forked and CSR operation 96 is performed in the child process so that parent process can return the 97 calling thread immediately. 98- OpenSSL library is used in generating CSR based on the algorithm type. 99- At present supporting generating CSR for only "RSA" algorithm type. 100- Parent process registers child process PID and a callback method in the 101 sd_event_lopp so that callback method is invoked upon completion 102 the CSR request in the child process. 103- Callback method invoked creates a CSR object with the status of the CSR 104 operation returned from the child process. 105- CSR read operation will return the CSR string if status is SUCCESS else throws 106 InternalFailure exception to the caller. 107- Certificate Manager implements "/xyz/openbmc_project/Certs/CSR/Create" 108 interface. 109- CSR object created implements "/xyz/openbmc_project/Certs/CSR" interface. 110- Caller needs to validate the CSR request parameters. 111- Caller need to wait on "InterfacesAdded" signal generated upon creation 112 of the CSR object to start reading CSR string. 113 114### Example usage for the GenerateCSR POST request 115 116 ``` 117 url: /redfish/v1/CertificateService 118 Action: #CertificateService.GenerateCSR { 119 "City": "HYB", 120 "CertificateCollection": "/redfish/v1/Managers/bmc/NetworkProtocol/HTTPS/Certificates/", 121 "CommonName": "www.company.com", 122 "ContactPerson":"myname", 123 "AlternativeNames":["mycompany.com","mycompany2.com"], 124 "ChallengePassword":"abc123", 125 "Email":"xxx@xx.com", 126 "GivenName":"localhost", 127 "Initials":"G", 128 "Country": "IN", 129 "KeyCurveId":"0", 130 "KeyUsage":["ServerAuthentication","ServerAuthentication"], 131 "KeyBitLength": 2048, 132 "KeyPairAlgorithm": "RSA", 133 "Organization": "ABCD", 134 "OrganizationUnit": "XY", 135 "State": "TX", 136 "SurName": "XX", 137 "UnstructuredName": "xxx" 138 } 139 Description: This is used to perform a certificate signing request. 140 Method: POST 141 142 ``` 143 144### Additional interfaces: 145- CertificateService.ReplaceCertificate 146 Allows the user to replace an existing certificate. 147 148### d-bus interfaces: 149 150#### d-bus interface to install certificate and private Key 151- Certs application must: 152 - validate the certificate and Private key file by checking, if the Private 153 key matches the public key in the certificate file. 154 - copy the certificate and Public Key file to the service specific path 155 based on a configuration file. 156 - Reload the listed service(s) for which the certificate is updated. 157 158#### d-bus interface to Delete certificate and Private Key 159 160- certificate manager should provide interface to delete the existing 161 certificate. 162- Incase of server type certificate deleting a signed certificate will 163 create a new self signed certificate and will install the same. 164 165### Boot process 166- certificate management instances should be created based on the system 167 configuration. 168 169- Incase of no Https certificate or invalid Https certificate, certificate 170 manager should update the https certificate with self signed certificate. 171 172### Repository: 173 phosphor-certificate-manager 174### Redfish Certificate Support 175#### Certificate Upload 176- Certificate Manager implements "xyz.openbmc_project.Certs.Install" interface 177 for installing certificates in the system. 178- Redfish initiates certificate upload by issuing a POST request on the Redfish 179 CertificateCollection with the certificate file. Acceptable body formats are: 180 raw pem text or json that is acceptable by action 181 [CertificateService.ReplaceCertificate]( 182 https://www.dmtf.org/sites/default/files/standards/documents/DSP2046_2019.1.pdf) 183 184 For example the HTTPS certificate upload POST request is issued on URI 185 "/redfish/v1/Managers/bmc/NetworkProtocol/HTTPS/Certificates" 186- Bmcweb receives the POST request and it maps the Redfish URI to the 187 corresponding Certificate Manager D-Bus URI. 188 e.g: HTTPS certificate collection URI 189 /redfish/v1/Managers/bmc/NetworkProtocol/HTTPS/Certificates mapped to 190 /xyz/openbmc_project/certs/server/https. 191- Bmcweb initiates an asynchronous call which invokes the "Install" method of 192 the Certificate Manager. 193- Certificate Manager "Install" method validates, installs the certificate file 194 and creates a Certificate object. 195- Certificate Manager initiates Reload of the Bmcweb service to trigger 196 configuration reload. 197- BMCweb service raises SIGHUP signal as part of Reload. 198- Bmcweb application handles the SIGHUP signal and reloads the SSL context with 199 the installed certificate. 200- Bmcweb invokes the Callback method with the status of the "Install" method 201 received from the Certificate Manager. 202- Callback method set the response message with error details for failure, sets 203 the response message with newly created certificate details for success. 204- Certificate object D-Bus path mapped to corresponding Redfish certificate URI. 205 e.g: /xyz/openbmc_project/certs/server/https/1 is mapped to 206 /redfish/v1/Managers/bmc/NetworkProtocol/HTTPS/Certificates/1 207 ID of the certificate is appended to the collection URI. 208 209#### Certificate Replace 210- Certificate Object implements "xyz.openbmc_project.Certs.Replace" interface to 211 for replacing existing certificate. 212- Redfish issues Replace certificate request by invoking the ReplaceCertificate 213 action of the CertificateService. 214- Redfish Certificate Collection URI is mapped to corresponding Certificate 215 D-Bus object URI 216 e.g: HTTPS certificate object 1 URI 217 /redfish/v1/Managers/bmc/NetworkProtocol/HTTPS/Certificates/1 is mapped to 218 /xyz/openbmc_project/certs/server/https/1. 219- Bmcweb receives POST request for Replace Certificate, invokes the Replace 220 D-Bus method of the Certificate object asynchronously. 221- Callback method will be passed to the bmcweb asynchronous method which will 222 called after completion of the D-Bus Replace method. 223- Callback method checks the response received, if failure response message is 224 set with error details, if success response message is set with the replaced 225 certificate details. 226 227#### Bootup 228- During bootup certificate objects created for the existing certificates. 229### Errors thrown by Certificate Manager 230- NotAllowed exception thrown if Install method invoked with a certificate 231 already existing. At present only one certificate per server and client 232 certificate type is allowed. 233- InvalidCertificate excption thrown for validation errors. 234 235#### Certificate Deletion 236- For server and client certificate type the certificate deletion is not 237 allowed. In case of authority certificate type the delete option is 238 acceptable and can be done on individial certificates, for example: 239 240 ``` 241 url: redfish/v1/Managers/bmc/Truststore/Certificates/1 242 Method: DELETE 243 244 Returns: code 204 with empty body content. 245 ``` 246 247