SUDOERS_TIMESTAMP(4)          File Formats Manual         SUDOERS_TIMESTAMP(4)

NNAAMMEE
     ssuuddooeerrss__ttiimmeessttaammpp - Sudoers Time Stamp Format

DDEESSCCRRIIPPTTIIOONN
     The ssuuddooeerrss plugin uses per-user time stamp files for credential caching.
     Once a user has been authenticated, they may use ssuuddoo without a password
     for a short period of time (5 minutes unless overridden by the
     _t_i_m_e_s_t_a_m_p___t_i_m_e_o_u_t option).  By default, ssuuddooeerrss uses a separate record
     for each terminal, which means that a user's login sessions are
     authenticated separately.  The _t_i_m_e_s_t_a_m_p___t_y_p_e option can be used to
     select the type of time stamp record ssuuddooeerrss will use.

     A multi-record time stamp file format was introduced in ssuuddoo 1.8.10 that
     uses a single file per user.  Previously, a separate file was used for
     each user and terminal combination unless tty-based time stamps were
     disabled.  The new format is extensible and records of multiple types and
     versions may coexist within the same file.

     All records, regardless of type or version, begin with a 16-bit version
     number and a 16-bit record size.

     Time stamp records have the following structure:

     /* Time stamp entry types */
     #define TS_GLOBAL               0x01    /* not restricted by tty or ppid */
     #define TS_TTY                  0x02    /* restricted by tty */
     #define TS_PPID                 0x03    /* restricted by ppid */
     #define TS_LOCKEXCL             0x04    /* special lock record */

     /* Time stamp flags */
     #define TS_DISABLED             0x01    /* entry disabled */
     #define TS_ANYUID               0x02    /* ignore uid, only valid in key */

     struct timestamp_entry {
         unsigned short version;     /* version number */
         unsigned short size;        /* entry size */
         unsigned short type;        /* TS_GLOBAL, TS_TTY, TS_PPID */
         unsigned short flags;       /* TS_DISABLED, TS_ANYUID */
         uid_t auth_uid;             /* uid to authenticate as */
         pid_t sid;                  /* session ID associated with tty/ppid */
         struct timespec start_time; /* session/ppid start time */
         struct timespec ts;         /* time stamp (CLOCK_MONOTONIC) */
         union {
             dev_t ttydev;           /* tty device number */
             pid_t ppid;             /* parent pid */
         } u;
     };

     The timestamp_entry struct fields are as follows:

     version
           The version number of the timestamp_entry struct.  New entries are
           created with a version number of 2.  Records with different version
           numbers may coexist in the same file but are not inter-operable.

     size  The size of the record in bytes.

     type  The record type, currently TS_GLOBAL, TS_TTY, or TS_PPID.

     flags
           Zero or more record flags which can be bit-wise ORed together.
           Supported flags are TS_DISABLED, for records disabled via ssuuddoo --kk
           and TS_ANYUID, which is used only when matching records.

     auth_uid
           The user ID that was used for authentication.  Depending on the
           value of the _r_o_o_t_p_w, _r_u_n_a_s_p_w and _t_a_r_g_e_t_p_w options, the user ID may
           be that of the invoking user, the root user, the default runas user
           or the target user.

     sid   The ID of the user's terminal session, if present.  The session ID
           is only used when matching records of type TS_TTY.

     start_time
           The start time of the session leader for records of type TS_TTY or
           of the parent process for records of type TS_PPID.  The _s_t_a_r_t___t_i_m_e
           is used to help prevent re-use of a time stamp record after a user
           has logged out.  Not all systems support a method to easily
           retrieve a process's start time.  The _s_t_a_r_t___t_i_m_e field was added in
           ssuuddooeerrss version 1.8.22 for the second revision of the
           timestamp_entry struct.

     ts    The actual time stamp.  A monotonic time source (which does not
           move backward) is used if the system supports it.  Where possible,
           ssuuddooeerrss uses a monotonic timer that increments even while the
           system is suspended.  The value of _t_s is updated each time a
           command is run via ssuuddoo.  If the difference between _t_s and the
           current time is less than the value of the _t_i_m_e_s_t_a_m_p___t_i_m_e_o_u_t
           option, no password is required.

     u.ttydev
           The device number of the terminal associated with the session for
           records of type TS_TTY.

     u.ppid
           The ID of the parent process for records of type TS_PPID.

LLOOCCKKIINNGG
     In ssuuddooeerrss versions 1.8.10 through 1.8.14, the entire time stamp file was
     locked for exclusive access when reading or writing to the file.
     Starting in ssuuddooeerrss 1.8.15, individual records are locked in the time
     stamp file instead of the entire file and the lock is held for a longer
     period of time.  This scheme is described below.

     The first record in the time stamp file is of type TS_LOCKEXCL and is
     used as a _l_o_c_k record to prevent more than one ssuuddoo process from adding a
     new record at the same time.  Once the desired time stamp record has been
     located or created (and locked), the TS_LOCKEXCL record is unlocked.  The
     lock on the individual time stamp record, however, is held until
     authentication is complete.  This allows ssuuddooeerrss to avoid prompting for a
     password multiple times when it is used more than once in a pipeline.

     Records of type TS_GLOBAL cannot be locked for a long period of time
     since doing so would interfere with other ssuuddoo processes.  Instead, a
     separate lock record is used to prevent multiple ssuuddoo processes using the
     same terminal (or parent process ID) from prompting for a password as the
     same time.

SSEEEE AALLSSOO
     sudoers(4), sudo(1m)

HHIISSTTOORRYY
     Originally, ssuuddoo used a single zero-length file per user and the file's
     modification time was used as the time stamp.  Later versions of ssuuddoo
     added restrictions on the ownership of the time stamp files and directory
     as well as sanity checks on the time stamp itself.  Notable changes were
     introduced in the following ssuuddoo versions:

     1.4.0
           Support for tty-based time stamp file was added by appending the
           terminal name to the time stamp file name.

     1.6.2
           The time stamp file was replaced by a per-user directory which
           contained any tty-based time stamp files.

     1.6.3p2
           The target user name was added to the time stamp file name when the
           _t_a_r_g_e_t_p_w option was set.

     1.7.3
           Information about the terminal device was stored in tty-based time
           stamp files for sanity checking.  This included the terminal device
           numbers, inode number and, on systems where it was not updated when
           the device was written to, the inode change time.  This helped
           prevent re-use of the time stamp file after logout.

     1.8.6p7
           The terminal session ID was added to tty-based time stamp files to
           prevent re-use of the time stamp by the same user in a different
           terminal session.  It also helped prevent re-use of the time stamp
           file on systems where the terminal device's inode change time was
           updated by writing.

     1.8.10
           A new, multi-record time stamp file format was introduced that uses
           a single file per user.  The terminal device's change time was not
           included since most systems now update the change time after a
           write is performed as required by POSIX.

     1.8.15
           Individual records are locked in the time stamp file instead of the
           entire file and the lock is held until authentication is complete.

     1.8.22
           The start time of the terminal session leader or parent process is
           now stored in non-global time stamp records.  This prevents re-use
           of the time stamp file after logout in most cases.

           Support was added for the kernel-based tty time stamps available in
           OpenBSD which do not use an on-disk time stamp file.

AAUUTTHHOORRSS
     Many people have worked on ssuuddoo over the years; this version consists of
     code written primarily by:

           Todd C. Miller

     See the CONTRIBUTORS file in the ssuuddoo distribution
     (https://www.sudo.ws/contributors.html) for an exhaustive list of people
     who have contributed to ssuuddoo.

BBUUGGSS
     If you feel you have found a bug in ssuuddoo, please submit a bug report at
     https://bugzilla.sudo.ws/

SSUUPPPPOORRTT
     Limited free support is available via the sudo-users mailing list, see
     https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search
     the archives.

DDIISSCCLLAAIIMMEERR
     ssuuddoo is provided "AS IS" and any express or implied warranties,
     including, but not limited to, the implied warranties of merchantability
     and fitness for a particular purpose are disclaimed.  See the LICENSE
     file distributed with ssuuddoo or https://www.sudo.ws/license.html for
     complete details.

Sudo 1.8.26                     October 7, 2018                    Sudo 1.8.26
