prpasswd, prpwd - Protected password authentication database files (Enhanced Security)
An authentication profile is maintained for each user on the system. A user profile is kept in a protected password database file that is accessible only to trusted programs acting on behalf of the trusted computing base (TCB). The protected password database files contain among other things the encrypted password for the user account. By default, prpasswd information is now in database format as converted by convauth. The databases are not converted in an update installation. On a trusted system, the encrypted password must be hidden from untrusted users.
The protected password database files do not eliminate the need for the /etc/passwd and the /etc/group files. Users must be defined in the passwd file in order to use the system. The protected password database file for a user contains the user name and user ID to provide a correlation to the user's /etc/passwd entry. There must be a match or the user account is treated as invalid.
Protected password database files are maintained in the /tcb/files/auth hierarchy. This directory contains other directories each named with a single letter from the alphabet. User authentication profiles are stored in these directories based on the first letter of the user account name. The name of a protected password database file is the name of the user not prpasswd. This enables an efficient search operation to locate the file for a specific user name. For instance, the authentication profile for the root account is located in the /tcb/files/auth/r directory and can be accessed by opening the file /tcb/files/auth/r/root.
Each file defines a user's authentication profile by specifying values that are interpreted by trusted programs acting as part of the TCB. Fields defined in a file are user-specific values and are used before a system default value for the same field is used. A default value may be referenced in one of three ways: If the user database contains a reference to a template, and the user has not defined a user-specific value, the value in the template file is used. If neither the user database or template file defines a value for a field and the system default database defines a value for a field, that value is used. If none of the databases defines a value for a field, a system default is defined for the field. Trusted programs check first for the existence of user-specific parameters before using a system default value.
A protected password database file contains keyword field identifiers and depending on the field type a value for that field (certain field types do not require an explicit value). The exact syntax for field specifications is consistent for all authentication databases and is described in the authcap(4) reference page. The keyword field identifiers supported by the protected password database file and their associated functions are as follows: This is the user name for the account. The string must match the name of the file and a user name in a corresponding /etc/passwd entry. The maximum length for DIGITAL UNIX user names is 8 characters. This limit is strictly enforced by enhanced security. This is the user ID for the account. The number must match the user ID field of the corresponding /etc/passwd entry. This field contains the encrypted password string for the account if the account has a password. This is a priority number used by authentication programs to modify the nice value of a login process for the user (see the setpriority(2) reference page). This field is the numeric value corresponding to SET_PROC_ACNTL. This number is used in conjunction with the u_auditmask mask. This field consists of a comma-separated list of audit event names. The events are the same as those specified in the auditmask(8) reference page. An entry of u_auditmask=all specifies all system calls and trusted events. This field specifies the minimum password change time in seconds. If the number is nonzero, the password cannot be changed until the specified number of seconds since the last successful password change have passed unless the person changing the password is authorized to override this constraint. The number in this field specifies the maximum length of the user account password and should be less than the system-wide maximum value defined by the <prot.h> constant AUTH_MAX_PASSWD_LENGTH. The number in this field specifies the minimum length of the user account password. If the field is zero, a dynamic value is calculated as defined in the Green Book. The number in this field is a time_t value that specifies how long from a successful change until the account password expires. When a password expires, system authentication programs will request that the password be changed when the user logs in to the system. If the password lifetime expires before the password is changed, the account is locked. The number in this field is a time_t value that specifies the lifetime of a password. If this time interval is reached, the account is locked and can only be unlocked by an authorized system administrator. The time in this field is a time_t value that indicates the time of the last successful password change. This field should only be set by programs that can be used to change the account password. The time in this field is a time_t value that indicates the time of the last unsuccessful password change. This field should only be set by programs that can be used to change the account password. This field controls the ability of the user to pick a password for the account. A :u_pickpw: entry indicates that the user can pick his own password; a :u_pickpw@: entry indicates that he cannot. This permits an account to be configured so that a user cannot pick a password but instead has a password generated by the system. This field controls the ability of a user to generate a password for the account. A :u_genpwd: entry indicates that the system will generate the password for the user; a :u_genpwd@: entry indicates that the user can pick his own password. The system is capable of generating passwords containing random words. This field controls whether password triviality checks are performed on any user-selected passwords. A :u_restrict: entry indicates that triviality checks are performed; a :u_restrict@: entry indicates they are not performed. Triviality checks include verifying that the password is not a login or group name, a palindrome, or a word recognized by the spell program. See the acceptable_password(3) reference page for more information on triviality checks for passwords. This field controls the ability of the user to choose a null password for the account. A :u_nullpw: entry indicates a null password can be chosen; a :u_nullpw@: entry indicates that it cannot. This field is a string representing the user name of the last person to change the account password if that user was not the account's owner. This is used to warn the user at login time if the account password has been changed, possibly without the knowledge of the user. This field controls the ability of the user to generate random characters for a password. A :u_genchars: entry indicates that the user can generate passwords made up of random characters; a :u_genchars@: entry indicates that he cannot. This field controls the ability of the user to generate random letters for a password. A :u_genletters: entry indicates that the user can generate passwords made up of random letters; a :u_genletters@: entry indicates that he cannot. This field is a number (0 to 9) representing the number of old encrypted passwords to keep to prevent reuse of previously used passwords. This field is a comma-separated list strings representing the old encrypted passwords. The length of the list is determined by u_pwdepth. This field is the algorithm number used to encrypt the current password. This field is the algorithm number used to encrypt future passwords. This field is a string that contains a comma-separated list of time-of-day specification entries that control when the user account can be used for login. The time in this field is a time_t value that contains the system time of the last successful login to the account. The time in this field is a time_t value that contains the system time of the last unsuccessful login to the account. This field is a character string that identifies the name of the terminal associated with the last successful login to the account. This field contains a number indicating the number of unsuccessful login attempts to the account. This field is reset when a successful login to the account occurs. If a login is attempted during the time period from u_unsuclog to u_unsuclog plus u_unlock, andu_numunsuclog is not less than u_maxtries, the login is refused. (This check is suppressed if the u_maxtries field is set to zero.) This field is a character string that identifies the name of the terminal associated with the last unsuccessful login attempt to the account. The number in this field specifies the maximum number of consecutive unsuccessful login attempts to the account that are permitted until the account is locked. Setting this field to 0 prevents the account from being disabled because of retry failures. In this case, u_numunsuclog is incremented but not checked. This field indicates whether the account is retired or not. An account that has been retired cannot be used for any purpose. A :u_retired: entry indicates that the account is retired; a :u_retired@: entry indicates that it is not. This field is used to administratively lock an account. A :u_lock: entry indicates that the account is locked; a :u_lock@: entry indicates that it is not. A user cannot log in to a locked account. An account can also be locked by other means. See getprpwent(3) for more information on locks. This field is a number indicating the time in seconds to wait before unlocking the account after an unsuccessful login attempt (u_unsuclog). This field is used to control whether the /tcb/bin/pwpolicy file is consulted for validating password changes. A :u_policy: entry indicates that the /tcb/bin/pwpolicy file is consulted; a :u_policy@: entry indicates that it is not. The actual time of type time_t that an account is set to expire. This field is a numeric value of type time_t that indicates the start of user's scheduled vacation. This field is a numeric value of type time_t that indicates the end of user's scheduled vacation. The RLIMIT_CPU rlim_max numeric value set by the setrlimit() system call at login time. The RLIMIT_FSIZE rlim_max numeric value set by the setrlimit() system call at login time. The RLIMIT_DATA rlim_max numeric value set by the setrlimit() system call at login time. The RLIMIT_STACK rlim_max numeric value set by the setrlimit() system call at login time. The RLIMIT_CORE rlim_max numeric value set by the setrlimit() system call at login time. The RLIMIT_RSS rlim_max numeric value set by the setrlimit() system call at login time. The RLIMIT_NOFILE rlim_max numeric value set by the setrlimit() system call at login time. The RLIMIT_VMEM rlim_max numeric value set by the setrlimit() system call at login time. A numeric value representing the maximum time, in seconds, since last successful login before account is locked. If set for an account (or system-wide), the user is automatically considered "locked out" if the last successful login was more than the specified interval before the current time. As with other is_locked_out() checks, the grace-period feature allows an override. This filed is a numeric value of type time_t. In a user profile, it is the timestamp until which automatic lockouts are bypassed (so locked_out_es() says no). In the system defaults database, it is the interval to be added to the current time when clicking on Unlock Account in the dxaccounts GUI.
This field allows a time-limited bypass to the is_locked_out() checks so an administrator can allow a user to log in until a specified time of day (for example, until 5pm). This bypasses anything except the u_lock administration lock on an account. A boolean expression indicating that the administrator requires a password change now. Unlike zeroing the u_suclog field, this still obeys the password lifetime requirements before refusing further logins. Note: While the old method of zeroing fd_schange still works, this method conforms to the Green Book. This field is the name of the template which provides default values for those fields for which no user-specific value is defined.
The u_vacation_* fields allow the user to specify a start and end date/time for vacation. This causes the login/password controls to ignore that period of time for things like password lifetime and "you must log in every so often". In order to retain Green Book conformance, it also disallows logins during that timespan.
The setrlimit() system call controls or restricts system resources some (or all) users. These resources include how much CPU time they can have, how much virtual address space they can have (how much swap space), how many file descriptors they can have open, and each of the other things (total of 8) controlled through setrlimit(). This sets hard limits, and restrics soft limits to match if they would otherwise be over the new hard limits.
The getprpwent routines are used to parse the protected password database files into a prpasswd structure that can be used by programs. A flag in the structure indicates whether a particular field in the structure and hence the field is defined. System default values are also provided in the structure. These values are derived from the /etc/auth/system/default file and can be used by programs in the absence of a user-specific value.
The following example shows a typical protected password database file:
This protected password database file is for the user perry. The user ID for perry is 101. This value must match the /etc/passwd entry for this user. The account has a password and its encrypted form is specified by the u_pwd field.
The database file specifies a minimum password change time of 0, indicating that the password can be changed at any time. Furthermore, the account is permitted to have a null password. The account has a maximum consecutive unsuccessful login threshold of 3, indicating that the account is locked after three failed attempts. The remaining fields provide account information such as the last successful and unsuccessful password change times as well as the last successful and unsuccessful login times and terminal names.
Specifies the pathname of the protected password database files. The system default database that defines system-wide global parameters.
Commands: login(1), passwd(1), auditmask(8), authck(8)
System Calls: setrlimit(2)
Functions: nice(3), acceptable_password(3), getprpwent(3), time_lock(3)
Files: authcap(4), default(4), group(4), passwd(4) delim off delim off