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compatsessionlog.go
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/
compatsessionlog.go
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/*
Copyright 2017 Gravitational, Inc.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package events
import (
"bufio"
"compress/gzip"
"encoding/json"
"fmt"
"os"
"path/filepath"
"sync"
"time"
"github.com/gravitational/teleport"
"github.com/gravitational/teleport/lib/session"
"github.com/gravitational/trace"
"github.com/jonboulle/clockwork"
log "github.com/sirupsen/logrus"
)
// DELETE IN: 2.6.0
// CompatSessionLogger is used only during upgrades from 2.4.0 to 2.5.0
// Should be deleted in 2.6.0 releases
// CompatSessionLoggerConfig sets up parameters for disk session logger
// associated with the session ID
type CompatSessionLoggerConfig struct {
// SessionID is the session id of the logger
SessionID session.ID
// DataDir is data directory for session events files
DataDir string
// Clock is the clock replacement
Clock clockwork.Clock
// RecordSessions controls if sessions are recorded along with audit events.
RecordSessions bool
}
// DELETE IN: 2.6.0
// CompatSessionLogger is used only during upgrades from 2.4.0 to 2.5.0
// Should be deleted in 2.6.0 releases
// NewCompatSessionLogger creates new disk based session logger
func NewCompatSessionLogger(cfg CompatSessionLoggerConfig) (*CompatSessionLogger, error) {
var err error
lastPrintEvent, err := readLastPrintEvent(eventsFileName(cfg.DataDir, cfg.SessionID, 0))
if err != nil {
if !trace.IsNotFound(err) {
return nil, trace.Wrap(err)
}
// no last event is ok
lastPrintEvent = nil
}
indexFile, err := os.OpenFile(filepath.Join(cfg.DataDir, fmt.Sprintf("%v.index", cfg.SessionID.String())), os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0640)
if err != nil {
return nil, trace.Wrap(err)
}
sessionLogger := &CompatSessionLogger{
Entry: log.WithFields(log.Fields{
trace.Component: teleport.ComponentAuditLog,
trace.ComponentFields: log.Fields{
"sid": cfg.SessionID,
},
}),
indexFile: indexFile,
CompatSessionLoggerConfig: cfg,
lastPrintEvent: lastPrintEvent,
}
return sessionLogger, nil
}
// CompatSessionLogger implements a disk based session logger. The imporant
// property of the disk based logger is that it never fails and can be used as
// a fallback implementation behind more sophisticated loggers.
type CompatSessionLogger struct {
CompatSessionLoggerConfig
*log.Entry
sync.Mutex
indexFile *os.File
eventsFile *gzipWriter
chunksFile *gzipWriter
// lastPrintEvent is the last written session event
lastPrintEvent *printEvent
}
func (sl *CompatSessionLogger) flush() error {
var err, err2 error
if sl.RecordSessions && sl.chunksFile != nil {
err = sl.chunksFile.Flush()
}
if sl.eventsFile != nil {
err2 = sl.eventsFile.Flush()
}
return trace.NewAggregate(err, err2)
}
// LogEvent logs an event associated with this session
func (sl *CompatSessionLogger) LogEvent(fields EventFields) error {
sl.Lock()
defer sl.Unlock()
if err := sl.openEventsFile(); err != nil {
return trace.Wrap(err)
}
sl.Debugf("LogEvent: %v to %v", fields, sl.eventsFile.file.Name())
if _, ok := fields[EventTime]; !ok {
fields[EventTime] = sl.Clock.Now().In(time.UTC).Round(time.Millisecond)
}
data, err := json.Marshal(fields)
if err != nil {
return trace.Wrap(err)
}
_, err = fmt.Fprintln(sl.eventsFile, string(data))
if err != nil {
return trace.Wrap(err)
}
return sl.flush()
}
// readLastEvent reads last event from the file, it opens
// the file in read only mode and closes it after
func readLastPrintEvent(fileName string) (*printEvent, error) {
f, err := os.Open(fileName)
if err != nil {
return nil, trace.ConvertSystemError(err)
}
defer f.Close()
reader, err := gzip.NewReader(f)
if err != nil {
return nil, trace.Wrap(err)
}
defer reader.Close()
scanner := bufio.NewScanner(reader)
var lastEvent *printEvent
for scanner.Scan() {
if len(scanner.Bytes()) == 0 {
continue
}
var event printEvent
if err = json.Unmarshal(scanner.Bytes(), &event); err != nil {
return nil, trace.Wrap(err)
}
if event.Type == SessionPrintEvent {
lastEvent = &event
}
}
if lastEvent == nil {
return nil, trace.NotFound("no session print events found")
}
return lastEvent, nil
}
// Close is called when clients close on the requested "session writer".
// We ignore their requests because this writer (file) should be closed only
// when the session logger is closed
func (sl *CompatSessionLogger) Close() error {
sl.Debugf("Close")
return nil
}
// Finalize is called by the session when it's closing. This is where we're
// releasing audit resources associated with the session
func (sl *CompatSessionLogger) Finalize() error {
sl.Lock()
defer sl.Unlock()
sl.Debugf("Finalize")
auditOpenFiles.Dec()
if sl.indexFile != nil {
sl.indexFile.Close()
}
if sl.chunksFile != nil {
sl.chunksFile.Close()
}
if sl.eventsFile != nil {
sl.eventsFile.Close()
}
return nil
}
// PostSessionSlice takes series of events associated with the session
// and writes them to events files and data file for future replays
func (sl *CompatSessionLogger) PostSessionSlice(slice SessionSlice) error {
sl.Lock()
defer sl.Unlock()
for i := range slice.Chunks {
_, err := sl.writeChunk(slice.Chunks[i])
if err != nil {
return trace.Wrap(err)
}
}
return sl.flush()
}
// writeChunk takes a stream of bytes (usually the output from a session terminal)
// and writes it into a "stream file", for future replay of interactive sessions.
func (sl *CompatSessionLogger) writeChunk(chunk *SessionChunk) (written int, err error) {
// when session recording is turned off, don't record the session byte stream
if sl.RecordSessions == false {
return len(chunk.Data), nil
}
if err := sl.openChunksFile(); err != nil {
return -1, trace.Wrap(err)
}
if written, err = sl.chunksFile.Write(chunk.Data); err != nil {
return written, trace.Wrap(err)
}
err = sl.writePrintEvent(time.Unix(0, chunk.Time), len(chunk.Data))
return written, trace.Wrap(err)
}
// writePrintEvent logs print event indicating write to the session
func (sl *CompatSessionLogger) writePrintEvent(start time.Time, bytesWritten int) error {
if err := sl.openEventsFile(); err != nil {
return trace.Wrap(err)
}
start = start.In(time.UTC).Round(time.Millisecond)
offset := int64(0)
delayMilliseconds := int64(0)
if sl.lastPrintEvent != nil {
offset = sl.lastPrintEvent.Offset + sl.lastPrintEvent.Bytes
delayMilliseconds = diff(sl.lastPrintEvent.Start, start) + sl.lastPrintEvent.DelayMilliseconds
}
event := printEvent{
Start: start,
Type: SessionPrintEvent,
Bytes: int64(bytesWritten),
DelayMilliseconds: delayMilliseconds,
Offset: offset,
}
bytes, err := json.Marshal(event)
if err != nil {
return trace.Wrap(err)
}
_, err = fmt.Fprintln(sl.eventsFile, string(bytes))
if err != nil {
return trace.Wrap(err)
}
sl.lastPrintEvent = &event
return trace.Wrap(err)
}
func (sl *CompatSessionLogger) openEventsFile() error {
if sl.eventsFile != nil {
return nil
}
eventsFileName := eventsFileName(sl.DataDir, sl.SessionID, 0)
// udpate the index file to write down that new events file has been created
data, err := json.Marshal(indexEntry{
FileName: filepath.Base(eventsFileName),
Type: fileTypeEvents,
Index: 0,
})
if err != nil {
return trace.Wrap(err)
}
_, err = fmt.Fprintf(sl.indexFile, "%v\n", string(data))
if err != nil {
return trace.Wrap(err)
}
// open new events file for writing
file, err := os.OpenFile(eventsFileName, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0640)
if err != nil {
return trace.Wrap(err)
}
sl.eventsFile = newGzipWriter(file)
return nil
}
func (sl *CompatSessionLogger) openChunksFile() error {
if sl.chunksFile != nil {
return nil
}
// chunksFileName consists of session id and the first global offset recorded
chunksFileName := chunksFileName(sl.DataDir, sl.SessionID, 0)
// udpate the index file to write down that new chunks file has been created
data, err := json.Marshal(indexEntry{
FileName: filepath.Base(chunksFileName),
Type: fileTypeChunks,
Offset: 0,
})
if err != nil {
return trace.Wrap(err)
}
_, err = fmt.Fprintf(sl.indexFile, "%v\n", string(data))
if err != nil {
return trace.Wrap(err)
}
// open new chunks file for writing
file, err := os.OpenFile(chunksFileName, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0640)
if err != nil {
return trace.Wrap(err)
}
sl.chunksFile = newGzipWriter(file)
return nil
}