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SUDO caching rules

Important sudo attributes

  • sudoHost - to what host does the rule apply
    • ALL - all hostnames
    • hostname
    • IP address
    • +netgroup
    • regular expression - contains one of “\?*[]”
  • sudoUser - to what user does the rule apply
    • username
    • #uid
    • %group
    • +netgroup
  • sudoOrder - rules ordering
  • sudoNotBefore and sudoNotAfter - time constraints

Complete LDAP schema can be found here.

Common

Per host update

Per host update returns all rules that:

  • sudoHost equals to ALL
  • direct match with sudoHost (by hostname or address)
  • contains regular expression (will be filtered by sudo)
  • contains netgroup (will be filtered by sudo)

Hostname match is performed in sudo source in plugin/sudoers/ldap.c/sudo_ldap_check_host().

Per user update

Per user update returns all rules that:

  • sudoUser equals to ALL
  • direct match with username, #uid or %group names
  • contains +netgroup (will be filtered by sudo)

Username match is performed via LADP filter in sudo source in plugin/sudoers/ldap.c/sudo_ldap_result_get().

Smart refresh

Download only rules that were modified or newly created since the last refresh.

Implementation

We will be looking for modified and newly created rules in short intervals. Expiration of the rules is handled per user during the execution time of sudo. We will also do periodical full refresh to ensure consistency even if the sudo command is not used.

SysDB attributes

sudoLastSmartRefreshTime on ou=SUDOers - when the last smart refresh was performed
sudoLastFullRefreshTime on ou=SUDOers - when the last full refresh was performed
sudoNextFullRefreshTime on ou=SUDOers - when the next full is scheduled
dataExpireTimestamp on each rule - when the rule will be considered as expired

Data provider

Data provider will be performing following actions:

A. Periodical download of changed or newly created rules (per host smart refresh)

Interval is configurable via ldap_sudo_changed_refresh_interval (default: 15 minutes)
Enable modifyTimestamp with ldap_sudo_modify_timestamp_enabled (default: false)

  1. if server has changed then do C
  2. else if entryUSN is available then
    1. refresh rules per host, where entryUSN \currentHighestUSN
    2. goto 3.2.
  3. else if modifyTimestamp is enabled then
    1. refresh rules per host, where entryUSN \currentHighestUSN
    2. sudoLastSmartRefreshTime := current time
    3. nextrefresh := (current time + ldap_sudo_changed_refresh_interval)
    4. if nextrefresh >= sudoNextFullRefreshTime AND nextrefresh < (sudoNextFullRefreshTime + ldap_sudo_changed_refresh_interval) then
      1. nextrefresh := (sudoNextFullRefreshTime + ldap_sudo_changed_refresh_interval)
    5. schedule next smart refresh
  4. else do nothing

B. Periodical full refresh of all rules

Configurable via ldap_sudo_full_refresh_interval (default: 360 minutes)

  1. do C
  2. sudoLastFullRefreshTime := current time
  3. sudoNextFullRefreshTime := (current time + ldap_sudo_full_refresh_interval)
  4. schedule next full refresh

C. On demand full refresh of all rules

  1. Download all rules per host
  2. Deletes all rules from the sysdb
  3. Store downloaded rule in the sysdb

D. On demand refresh of specific rules

  1. Download the rules
  2. Delete them from the sysdb
  3. Store downloaded rule in the sysdb

Responder

sudo_timed (default: false) - filter rules by time constraints?

  1. search sysdb per user
  2. refresh all expired rules
  3. if any rule was deleted then
    1. schedule C (out of band)
    2. search sysdb per user
  4. if sudo_timed = false then filter rules by time constraints
  5. sort rules
  6. return rules to sudo

Questions

  1. Should we also do per user smart updates when the user runs sudo?
  2. Should we create a tool to force full refresh of the rules immediately?