| F.40. sslinfo — obtain client SSL information | ||||
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F.40. sslinfo — obtain client SSL information#
Thesslinfo module provides information about the SSL certificate that the current client provided when connecting toPostgreSQL. The module is useless (most functions will return NULL) if the current connection does not use SSL.
Some of the information available through this module can also be obtained using the built-in system viewpg_stat_ssl.
This extension won't build at all unless the installation was configured with--with-ssl=openssl.
F.40.1. Functions Provided#
ssl_is_used() returns booleanReturns true if current connection to server uses SSL, and false otherwise.
ssl_version() returns textReturns the name of the protocol used for the SSL connection (e.g., TLSv1.0, TLSv1.1, TLSv1.2 or TLSv1.3).
ssl_cipher() returns textReturns the name of the cipher used for the SSL connection (e.g., DHE-RSA-AES256-SHA).
ssl_client_cert_present() returns booleanReturns true if current client has presented a valid SSL client certificate to the server, and false otherwise. (The server might or might not be configured to require a client certificate.)
ssl_client_serial() returns numericReturns serial number of current client certificate. The combination of certificate serial number and certificate issuer is guaranteed to uniquely identify a certificate (but not its owner — the owner ought to regularly change their keys, and get new certificates from the issuer).
So, if you run your own CA and allow only certificates from this CA to be accepted by the server, the serial number is the most reliable (albeit not very mnemonic) means to identify a user.
ssl_client_dn() returns textReturns the full subject of the current client certificate, converting character data into the current database encoding. It is assumed that if you use non-ASCII characters in the certificate names, your database is able to represent these characters, too. If your database uses the SQL_ASCII encoding, non-ASCII characters in the name will be represented as UTF-8 sequences.
The result looks like
/CN=Somebody /C=Some country/O=Some organization.ssl_issuer_dn() returns textReturns the full issuer name of the current client certificate, converting character data into the current database encoding. Encoding conversions are handled the same as for
ssl_client_dn.The combination of the return value of this function with the certificate serial number uniquely identifies the certificate.
This function is really useful only if you have more than one trusted CA certificate in your server's certificate authority file, or if this CA has issued some intermediate certificate authority certificates.
ssl_client_dn_field(fieldname text) returns textThis function returns the value of the specified field in the certificate subject, or NULL if the field is not present. Field names are string constants that are converted into ASN1 object identifiers using theOpenSSL object database. The following values are acceptable:
commonName (alias CN)surname (alias SN)namegivenName (alias GN)countryName (alias C)localityName (alias L)stateOrProvinceName (alias ST)organizationName (alias O)organizationalUnitName (alias OU)titledescriptioninitialspostalCodestreetAddressgenerationQualifierdescriptiondnQualifierx500UniqueIdentifierpseudonymroleemailAddress
All of these fields are optional, except
commonName. It depends entirely on your CA's policy which of them would be included and which wouldn't. The meaning of these fields, however, is strictly defined by the X.500 and X.509 standards, so you cannot just assign arbitrary meaning to them.ssl_issuer_field(fieldname text) returns textSame as
ssl_client_dn_field, but for the certificate issuer rather than the certificate subject.ssl_extension_info() returns setof recordProvide information about extensions of client certificate: extension name, extension value, and if it is a critical extension.
F.40.2. Author#
Victor Wagner<vitus@cryptocom.ru>, Cryptocom LTD
Dmitry Voronin<carriingfate92@yandex.ru>
E-Mail of Cryptocom OpenSSL development group:<openssl@cryptocom.ru>