audit: config_change normalizations and event record gathering

Make a number of changes to normalize CONFIG_CHANGE records by adding missing op= fields, providing more information in existing op fields (optional last patch) and connecting all records to existing audit events. The user record needs special-casing since its content isn't directly related to the call that logs it.

Since tree purge records are processed after the EOE record is produced, the order of operation of the EOE record and the purge will have to be reversed so that the purge records can be included in the event.

The last patch is included for completeness understanding it may be more information than necessary.

For reference, here are the calling methods and function tree for all CONFIG_CHANGE events with fields:
- audit_log_config_change()
- add "op=set" to fields: "[op] <param-name> old auid ses subj res"
- AUDIT_SET:AUDIT_STATUS_PID
- AUDIT_SET:AUDIT_STATUS_LOST
- audit_do_config_change()
- AUDIT_SET:AUDIT_STATUS_FAILURE
- AUDIT_SET:AUDIT_STATUS_ENABLED
- AUDIT_SET:AUDIT_STATUS_RATE_LIMIT
- AUDIT_SET:AUDIT_STATUS_BACKLOG_LIMIT
- AUDIT_SET:AUDIT_STATUS_BACKLOG_WAIT_TIME
- audit_log_rule_change()
- fields: "auid ses subj op key list res"
- AUDIT_ADD_RULE -F dir=...
- AUDIT_DEL_RULE -F dir=...
- audit_log_common_recv_msg()
- fields: "pid uid auid ses subj ..."
- AUDIT_*USER* events (not CONFIG_CHANGE like all the rest)
- AUDIT_LOCKED add "op={add,remove}_rule" to "[op] audit_enabled res"
- AUDIT_TRIM "op=trim res"
- AUDIT_MAKE_EQUIV: "op=make_equiv old new res"
- AUDIT_TTY_SET: "op=tty_set old-enabled new-enabled old-log_passwd new-log_passwd res"
- audit_mark_log_rule_change()
- add ":mark" to op in fields: "uid ses op=autoremove_rule[] path key list res"
- audit_autoremove_mark_rule()
- audit_mark_handle_event()
- audit_mark_fsnotify_ops.handle_event
- audit_tree_log_remove_rule() called from kill_rules()
- add to op ":tree:%s" to fields: "op=remove_rule[] dir key list res"
- from trim_marked()
- AUDIT_TRIM: audit_trim_trees() "trim"
- audit_add_tree_rule() iterate_mounts err "add"
- audit_add_rule()
- audit_rule_change()
- AUDIT_ADD_RULE -F dir=...
- AUDIT_MAKE_EQUIV: audit_tag_tree() iterate_mounts err "equiv"
- from audit_kill_trees()
- __audit_free() "free"
- do_exit()
- copy_process() err
- __audit_syscall_exit() "exit"
- from evict_chunk() "evict"
- audit_tree_freeing_mark()
- audit_tree_ops.freeing_mark
- audit_watch_log_rule_change()
add to op ":watch:%s" to fields "auid ses op={updated,remove}_rule[] path key list res"
- audit_update_watch() "updated_rules:watch:inval" : "updated_rules:watch:set"
- audit_watch_handle_event() FS_CREATE|FS_MOVED_TO, FS_DELETE|FS_MOVED_FROM
- audit_watch_fsnotify_ops.handle_event
- audit_remove_parent_watches() "remove_rule:watch:parent"
- audit_watch_handle_event() FS_DELETE_SELF|FS_UNMOUNT|FS_MOVE_SELF
- audit_watch_fsnotify_ops.handle_event
- audit_seccomp_actions_logged()
- fields: "op actions old-actions res"

See: https://github.com/linux-audit/audit-kernel/issues/50
See: https://github.com/linux-audit/audit-kernel/issues/59

Sources of AUDIT_CONFIG_CHANGE records and their current and proposed fields are listed here

	https://github.com/linux-audit/audit-kernel/issues/59#issuecomment-445055154

Changelog:
v3:
- un-clever %s_rule to not break up op values
- create audit_log_user_recv_msg() and squash into record connection
- squash kill_trees context handling with kill-trees before EOE
- rebase on audit/next (v4.20-rc1) with 2a1fe215e730 ("audit: use current whenever possible")
- remove parens in extended format

v2:
- re-order audit_log_exit() and audit_kill_trees()
- drop EOE reordering patch
- rebase on 4.18-rc1 (audit/next)

Richard Guy Briggs (4):
audit: give a clue what CONFIG_CHANGE op was involved
audit: add syscall information to CONFIG_CHANGE records
audit: hand taken context to audit_kill_trees for syscall logging
audit: extend config_change mark/watch/tree rule changes

 kernel/audit.c          | 33 +++++++++++++++++++++++----------
 kernel/audit.h          |  4 ++--
 kernel/audit_fsnotify.c |  4 ++--
 kernel/audit_tree.c     | 28 +++++++++++++++-------------
 kernel/audit_watch.c    |  8 +++++---
 kernel/auditfilter.c    |  2 +-
 kernel/auditsc.c        | 12 ++++++------
 7 files changed, 54 insertions(+), 37 deletions(-)

1.8.3.1