Provided by: sudo_1.9.15p5-3ubuntu5_amd64 bug

NAME

     sudo_logsrv.proto — Sudo log server protocol

DESCRIPTION

     Starting with version 1.9.0, sudo supports sending event and I/O logs to a log server.  The
     protocol used is written in Google's Protocol Buffers domain specific language.  The
     EXAMPLES section includes a complete description of the protocol in Protocol Buffers format.

     Because there is no way to determine message boundaries when using Protocol Buffers, the
     wire size of each message is sent immediately preceding the message itself as a 32-bit
     unsigned integer in network byte order.  This is referred to as “length-prefix framing” and
     is how Google suggests handling the lack of message delimiters.

     The protocol is made up of two basic messages, ClientMessage and ServerMessage, described
     below.  The server must accept messages up to two megabytes in size.  The server may return
     an error if the client tries to send a message larger than two megabytes.

Client Messages

     A ClientMessage is a container used to encapsulate all the possible message types a client
     may send to the server.

     message ClientMessage {
       oneof type {
         AcceptMessage accept_msg = 1;
         RejectMessage reject_msg = 2;
         ExitMessage exit_msg = 3;
         RestartMessage restart_msg = 4;
         AlertMessage alert_msg = 5;
         IoBuffer ttyin_buf = 6;
         IoBuffer ttyout_buf = 7;
         IoBuffer stdin_buf = 8;
         IoBuffer stdout_buf = 9;
         IoBuffer stderr_buf = 10;
         ChangeWindowSize winsize_event = 11;
         CommandSuspend suspend_event = 12;
         ClientHello hello_msg = 13;
       }
     }

     The different ClientMessage sub-messages the client may sent to the server are described
     below.

   TimeSpec
     message TimeSpec {
         int64 tv_sec = 1;
         int32 tv_nsec = 2;
     }

     A TimeSpec is the equivalent of a POSIX struct timespec, containing seconds and nanoseconds
     members.  The tv_sec member is a 64-bit integer to support dates after the year 2038.

   InfoMessage
     message InfoMessage {
       message StringList {
         repeated string strings = 1;
       }
       message NumberList {
         repeated int64 numbers = 1;
       }
       string key = 1;
       oneof value {
         int64 numval = 2;
         string strval = 3;
         StringList strlistval = 4;
         NumberList numlistval = 5;
       }
     }

     An InfoMessage is used to represent information about the invoking user as well as the
     execution environment the command runs in the form of key-value pairs.  The key is always a
     string but the value may be a 64-bit integer, a string, an array of strings, or an array of
     64-bit integers.  The event log data is composed of InfoMessage entries.  See the EVENT LOG
     VARIABLES section for more information.

   ClientHello hello_msg
     message ClientHello {
       string client_id = 1;
     }

     A ClientHello message consists of client information that may be sent to the server when the
     client first connects.

     client_id
             A free-form client description.  This usually includes the name and version of the
             client implementation.

   AcceptMessage accept_msg
     message AcceptMessage {
       TimeSpec submit_time = 1;
       repeated InfoMessage info_msgs = 2;
       bool expect_iobufs = 3;
     }

     An AcceptMessage is sent by the client when a command is allowed by the security policy.  It
     contains the following members:

     submit_time
             The wall clock time when the command was submitted to the security policy.

     info_msgs
             An array of InfoMessage describing the user who submitted the command as well as the
             execution environment of the command.  This information is used to generate an event
             log entry and may also be used by server to determine where and how the I/O log is
             stored.

     expect_iobufs
             Set to true if the server should expect IoBuffer messages to follow (for I/O
             logging) or false if the server should only store the event log.

     If an AcceptMessage is sent, the client must not send a RejectMessage or RestartMessage.

   RejectMessage reject_msg
     message RejectMessage {
       TimeSpec submit_time = 1;
       string reason = 2;
       repeated InfoMessage info_msgs = 3;
     }

     A RejectMessage is sent by the client when a command is denied by the security policy.  It
     contains the following members:

     submit_time
             The wall clock time when the command was submitted to the security policy.

     reason  The reason the security policy gave for denying the command.

     info_msgs
             An array of InfoMessage describing the user who submitted the command as well as the
             execution environment of the command.  This information is used to generate an event
             log entry.

     If a RejectMessage is sent, the client must not send an AcceptMessage or RestartMessage.

   ExitMessage exit_msg
     message ExitMessage {
       TimeSpec run_time = 1;
       int32 exit_value = 2;
       bool dumped_core = 3;
       string signal = 4;
       string error = 5;
     }

     An ExitMessage is sent by the client after the command has exited or has been terminated by
     a signal.  It contains the following members:

     run_time
             The total amount of elapsed time since the command started, calculated using a
             monotonic clock where possible.  This is not the wall clock time.

     exit_value
             The command's exit value in the range 0-255.

     dumped_core
             True if the command was terminated by a signal and dumped core.

     signal  If the command was terminated by a signal, this is set to the name of the signal
             without the leading “SIG”.  For example, INT, TERM, KILL, SEGV.

     error   A message from the client indicating that the command was terminated unexpectedly
             due to an error.

     When performing I/O logging, the client should wait for a commit_point corresponding to the
     final IoBuffer before closing the connection unless the final commit_point has already been
     received.

   RestartMessage restart_msg
     message RestartMessage {
       string log_id = 1;
       TimeSpec resume_point = 2;
     }

     A RestartMessage is sent by the client to resume sending an existing I/O log that was
     previously interrupted.  It contains the following members:

     log_id  The the server-side name for an I/O log that was previously sent to the client by
             the server.  This may be a path name on the server or some other kind of server-side
             identifier.

     resume_point
             The point in time after which to resume the I/O log.  This is in the form of a
             TimeSpec representing the amount of time since the command started, not the wall
             clock time.  The resume_point should correspond to a commit_point previously sent to
             the client by the server.  If the server receives a RestartMessage containing a
             resume_point it has not previously seen, an error will be returned to the client and
             the connection will be dropped.

     If a RestartMessage is sent, the client must not send an AcceptMessage or RejectMessage.

   AlertMessage alert_msg
     message AlertMessage {
       TimeSpec alert_time = 1;
       string reason = 2;
       repeated InfoMessage info_msgs = 3;
     }

     An AlertMessage is sent by the client to indicate a problem detected by the security policy
     while the command is running that should be stored in the event log.  It contains the
     following members:

     alert_time
             The wall clock time when the alert occurred.

     reason  The reason for the alert.

     info_msgs
             An optional array of InfoMessage describing the user who submitted the command as
             well as the execution environment of the command.  This information is used to
             generate an event log entry.

   IoBuffer ttyin_buf | ttyout_buf | stdin_buf | stdout_buf | stderr_buf
     message IoBuffer {
       TimeSpec delay = 1;
       bytes data = 2;
     }

     An IoBuffer is used to represent data from terminal input, terminal output, standard input,
     standard output, or standard error.  It contains the following members:

     delay   The elapsed time since the last record in the form of a TimeSpec.  The delay should
             be calculated using a monotonic clock where possible.

     data    The binary I/O log data from terminal input, terminal output, standard input,
             standard output, or standard error.

   ChangeWindowSize winsize_event
     message ChangeWindowSize {
       TimeSpec delay = 1;
       int32 rows = 2;
       int32 cols = 3;
     }

     A ChangeWindowSize message is sent by the client when the terminal running the command
     changes size.  It contains the following members:

     delay   The elapsed time since the last record in the form of a TimeSpec.  The delay should
             be calculated using a monotonic clock where possible.

     rows    The new number of terminal rows.

     cols    The new number of terminal columns.

   CommandSuspend suspend_event
     message CommandSuspend {
       TimeSpec delay = 1;
       string signal = 2;
     }

     A CommandSuspend message is sent by the client when the command is either suspended or
     resumed.  It contains the following members:

     delay   The elapsed time since the last record in the form of a TimeSpec.  The delay should
             be calculated using a monotonic clock where possible.

     signal  The signal name without the leading “SIG”.  For example, STOP, TSTP, CONT.

Server Messages

     A ServerMessage is a container used to encapsulate all the possible message types the server
     may send to a client.

     message ServerMessage {
       oneof type {
         ServerHello hello = 1;
         TimeSpec commit_point = 2;
         string log_id = 3;
         string error = 4;
         string abort = 5;
       }
     }

     The different ServerMessage sub-messages the server may sent to the client are described
     below.

   ServerHello hello
     message ServerHello {
       string server_id = 1;
       string redirect = 2;
       repeated string servers = 3;
       bool subcommands = 4;
     }

     The ServerHello message consists of server information sent when the client first connects.
     It contains the following members:

     server_id
             A free-form server description.  Usually this includes the name and version of the
             implementation running on the log server.  This member is always present.

     redirect
             A host and port separated by a colon (‘’): that the client should connect to
             instead.  The host may be a host name, an IPv4 address, or an IPv6 address in square
             brackets.  This may be used for server load balancing.  The server will disconnect
             after sending the ServerHello when it includes a redirect.

     servers
             A list of other known log servers.  This can be used to implement log server
             redundancy and allows the client to discover all other log servers simply by
             connecting to one known server.  This member may be omitted when there is only a
             single log server.

     subcommands
             If set, the server supports logging additional commands during a session.  The
             client may send an AcceptMessage or RejectMessage when sudo is running in intercept
             mode.  In this mode, commands spawned from the initial command authorized by sudo
             are subject to policy restrictions and/or are logged.  If subcommands is false, the
             client must not attempt to log additional commands.

   TimeSpec commit_point
     A periodic time stamp sent by the server to indicate when I/O log buffers have been
     committed to storage.  This message is not sent after every IoBuffer but rather at a server-
     configurable interval.  When the server receives an ExitMessage, it will respond with a
     commit_point corresponding to the last received IoBuffer before closing the connection.

   string log_id
     The server-side ID of the I/O log being stored, sent in response to an AcceptMessage where
     expect_iobufs is true.

   string error
     A fatal server-side error.  The server will close the connection after sending the error
     message.

   string abort
     An abort message from the server indicates that the client should kill the command and
     terminate the session.  It may be used to implement simple server-side policy.  The server
     will close the connection after sending the abort message.

Protocol flow of control

     The expected protocol flow is as follows:

     1.   Client connects to the first available server.  If the client is configured to use TLS,
          a TLS handshake will be attempted.

     2.   Client sends ClientHello.  This is currently optional but allows the server to detect a
          non-TLS connection on the TLS port.

     3.   Server sends ServerHello.

     4.   Client responds with either AcceptMessage, RejectMessage, or RestartMessage.

     5.   If client sent a AcceptMessage with expect_iobufs set, server creates a new I/O log and
          responds with a log_id.

     6.   Client sends zero or more IoBuffer messages.

     7.   Server periodically responds to IoBuffer messages with a commit_point.

     8.   Client sends an ExitMessage when the command exits or is killed.

     9.   Server sends the final commit_point if one is pending.

     10.  Server closes the connection.  After receiving the final commit_point, the client shuts
          down its side of the TLS connection if TLS is in use, and closes the connection.

     11.  Server shuts down its side of the TLS connection if TLS is in use, and closes the
          connection.

     At any point, the server may send an error or abort message to the client at which point the
     server will close the connection.  If an abort message is received, the client should
     terminate the running command.

EVENT LOG VARIABLES

     AcceptMessage, AlertMessage and RejectMessage classes contain an array of InfoMessage that
     should contain information about the user who submitted the command as well as information
     about the execution environment of the command if it was accepted.

     Some variables have a client, run, or submit prefix.  These prefixes are used to eliminate
     ambiguity for variables that could apply to the client program, the user submitting the
     command, or the command being run.  Variables with a client prefix pertain to the program
     performing the connection to the log server, for example sudo.  Variables with a run prefix
     pertain to the command that the user requested be run.  Variables with a submit prefix
     pertain to the user submitting the request (the user running sudo).

     The following InfoMessage entries are required:

     Key            Type          Description
     command        string        command that was submitted
     runuser        string        name of user the command was run as
     submithost     string        name of host the command was submitted on
     submituser     string        name of user submitting the command

     The following InfoMessage entries are recognized, but not required:

     Key            Type          Description
     clientargv     StringList    client's original argument vector
     clientpid      int64         client's process ID
     clientppid     int64         client's parent process ID
     clientsid      int64         client's terminal session ID
     columns        int64         number of columns in the terminal
     lines          int64         number of lines in the terminal
     runargv        StringList    argument vector of command to run
     runchroot      string        root directory of command to run
     runcwd         string        running command's working directory
     runenv         StringList    the running command's environment
     rungid         int64         primary group-ID of the command
     rungids        NumberList    supplementary group-IDs for the command
     rungroup       string        primary group name of the command
     rungroups      StringList    supplementary group names for the command
     runuid         int64         run user's user-ID
     submitcwd      string        submit user's current working directory
     submitenv      StringList    the submit user's environment
     submitgid      int64         submit user's primary group-ID
     submitgids     NumberList    submit user's supplementary group-IDs
     submitgroup    string        submitting user's primary group name
     submitgroups   StringList    submit user's supplementary group names
     submituid      int64         submit user's user-ID
     ttyname        string        the terminal the command was submitted from

     The server must accept other variables not listed above but may ignore them.

EXAMPLES

     The Protocol Buffers description of the log server protocol, using “proto3” syntax, is
     included in full below.

     syntax = "proto3";

     /*
      * Client message to the server.  Messages on the wire are
      * prefixed with a 32-bit size in network byte order.
      */
     message ClientMessage {
       oneof type {
         AcceptMessage accept_msg = 1;
         RejectMessage reject_msg = 2;
         ExitMessage exit_msg = 3;
         RestartMessage restart_msg = 4;
         AlertMessage alert_msg = 5;
         IoBuffer ttyin_buf = 6;
         IoBuffer ttyout_buf = 7;
         IoBuffer stdin_buf = 8;
         IoBuffer stdout_buf = 9;
         IoBuffer stderr_buf = 10;
         ChangeWindowSize winsize_event = 11;
         CommandSuspend suspend_event = 12;
       }
     }

     /* Equivalent of POSIX struct timespec */
     message TimeSpec {
         int64 tv_sec = 1;           /* seconds */
         int32 tv_nsec = 2;          /* nanoseconds */
     }

     /* I/O buffer with keystroke data */
     message IoBuffer {
       TimeSpec delay = 1;           /* elapsed time since last record */
       bytes data = 2;               /* keystroke data */
     }

     /*
      * Key/value pairs, like Privilege Manager struct info.
      * The value may be a number, a string, or a list of strings.
      */
     message InfoMessage {
       message StringList {
         repeated string strings = 1;
       }
       message NumberList {
         repeated int64 numbers = 1;
       }
       string key = 1;
       oneof value {
         int64 numval = 2;
         string strval = 3;
         StringList strlistval = 4;
         NumberList numlistval = 5;
       }
     }

     /*
      * Event log data for command accepted by the policy.
      */
     message AcceptMessage {
       TimeSpec submit_time = 1;             /* when command was submitted */
       repeated InfoMessage info_msgs = 2;   /* key,value event log data */
       bool expect_iobufs = 3;               /* true if I/O logging enabled */
     }

     /*
      * Event log data for command rejected by the policy.
      */
     message RejectMessage {
       TimeSpec submit_time = 1;             /* when command was submitted */
       string reason = 2;                    /* reason command was rejected */
       repeated InfoMessage info_msgs = 3;   /* key,value event log data */
     }

     /* Message sent by client when command exits. */
     /* Might revisit runtime and use end_time instead */
     message ExitMessage {
       TimeSpec run_time = 1;        /* total elapsed run time */
       int32 exit_value = 2;         /* 0-255 */
       bool dumped_core = 3;         /* true if command dumped core */
       string signal = 4;            /* signal name if killed by signal */
       string error = 5;             /* if killed due to other error */
     }

     /* Alert message, policy module-specific. */
     message AlertMessage {
       TimeSpec alert_time = 1;              /* time alert message occurred */
       string reason = 2;                    /* policy alert error string */
       repeated InfoMessage info_msgs = 3;   /* key,value event log data */
     }

     /* Used to restart an existing I/O log on the server. */
     message RestartMessage {
       string log_id = 1;            /* ID of log being restarted */
       TimeSpec resume_point = 2;    /* resume point (elapsed time) */
     }

     /* Window size change event. */
     message ChangeWindowSize {
       TimeSpec delay = 1;           /* elapsed time since last record */
       int32 rows = 2;               /* new number of rows */
       int32 cols = 3;               /* new number of columns */
     }

     /* Command suspend/resume event. */
     message CommandSuspend {
       TimeSpec delay = 1;           /* elapsed time since last record */
       string signal = 2;            /* signal that caused suspend/resume */
     }

     /*
      * Server messages to the client.  Messages on the wire are
      * prefixed with a 32-bit size in network byte order.
      */
     message ServerMessage {
       oneof type {
         ServerHello hello = 1;      /* server hello message */
         TimeSpec commit_point = 2;  /* cumulative time of records stored */
         string log_id = 3;          /* ID of server-side I/O log */
         string error = 4;           /* error message from server */
         string abort = 5;           /* abort message, kill command */
       }
     }

     /* Hello message from server when client connects. */
     message ServerHello {
       string server_id = 1;         /* free-form server description */
       string redirect = 2;          /* optional redirect if busy */
       repeated string servers = 3;  /* optional list of known servers */
     }

SEE ALSO

     sudo_logsrvd.conf(5), sudoers(5), sudo(8), sudo_logsrvd(8)

     Protocol Buffers, https://developers.google.com/protocol-buffers/.

AUTHORS

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

           Todd C. Miller

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

BUGS

     If you believe you have found a bug in sudo, you can submit a bug report at
     https://bugzilla.sudo.ws/

SUPPORT

     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.

DISCLAIMER

     sudo 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.md file distributed with sudo or
     https://www.sudo.ws/about/license/ for complete details.