TUN-7543: Add --debug-stream flag to cloudflared access ssh

Allows for debugging the payloads that are sent in client mode to
the ssh server. Required to be run with --log-directory to capture
logging output. Additionally has maximum limit that is provided with
the flag that will only capture the first N number of reads plus
writes through the WebSocket stream. These reads/writes are not directly
captured at the packet boundary so some reconstruction from the
log messages will be required.

Added User-Agent for all out-going cloudflared access
tcp requests in client mode.
Added check to not run terminal logging in cloudflared access tcp
client mode to not obstruct the stdin and stdout.
This commit is contained in:
Devin Carr 2023-06-29 10:29:15 -07:00 committed by Jean Khawand
parent a929dcca45
commit 4fd284dbe7
4 changed files with 100 additions and 6 deletions

View File

@ -3,6 +3,7 @@ package access
import (
"crypto/tls"
"fmt"
"io"
"net/http"
"strings"
@ -13,6 +14,7 @@ import (
"github.com/cloudflare/cloudflared/carrier"
"github.com/cloudflare/cloudflared/config"
"github.com/cloudflare/cloudflared/logger"
"github.com/cloudflare/cloudflared/stream"
"github.com/cloudflare/cloudflared/validation"
)
@ -38,6 +40,7 @@ func StartForwarder(forwarder config.Forwarder, shutdown <-chan struct{}, log *z
if forwarder.TokenSecret != "" {
headers.Set(cfAccessClientSecretHeader, forwarder.TokenSecret)
}
headers.Set("User-Agent", userAgent)
carrier.SetBastionDest(headers, forwarder.Destination)
@ -58,7 +61,12 @@ func StartForwarder(forwarder config.Forwarder, shutdown <-chan struct{}, log *z
// useful for proxying other protocols (like ssh) over websockets
// (which you can put Access in front of)
func ssh(c *cli.Context) error {
log := logger.CreateSSHLoggerFromContext(c, logger.EnableTerminalLog)
// If not running as a forwarder, disable terminal logs as it collides with the stdin/stdout of the parent process
outputTerminal := logger.DisableTerminalLog
if c.IsSet(sshURLFlag) {
outputTerminal = logger.EnableTerminalLog
}
log := logger.CreateSSHLoggerFromContext(c, outputTerminal)
// get the hostname from the cmdline and error out if its not provided
rawHostName := c.String(sshHostnameFlag)
@ -76,6 +84,7 @@ func ssh(c *cli.Context) error {
if c.IsSet(sshTokenSecretFlag) {
headers.Set(cfAccessClientSecretHeader, c.String(sshTokenSecretFlag))
}
headers.Set("User-Agent", userAgent)
carrier.SetBastionDest(headers, c.String(sshDestinationFlag))
@ -121,7 +130,19 @@ func ssh(c *cli.Context) error {
return err
}
return carrier.StartClient(wsConn, &carrier.StdinoutStream{}, options)
var s io.ReadWriter
s = &carrier.StdinoutStream{}
if c.IsSet(sshDebugStream) {
maxMessages := c.Uint64(sshDebugStream)
if maxMessages == 0 {
// default to 10 if provided but unset
maxMessages = 10
}
logger := log.With().Str("host", hostname).Logger()
s = stream.NewDebugStream(s, &logger, maxMessages)
}
carrier.StartClient(wsConn, s, options)
return nil
}
func buildRequestHeaders(values []string) http.Header {

View File

@ -34,6 +34,7 @@ const (
sshTokenSecretFlag = "service-token-secret"
sshGenCertFlag = "short-lived-cert"
sshConnectTo = "connect-to"
sshDebugStream = "debug-stream"
sshConfigTemplate = `
Add to your {{.Home}}/.ssh/config:
@ -151,9 +152,12 @@ func Commands() []*cli.Command {
EnvVars: []string{"TUNNEL_SERVICE_TOKEN_SECRET"},
},
&cli.StringFlag{
Name: logger.LogSSHDirectoryFlag,
Aliases: []string{"logfile"}, //added to match the tunnel side
Usage: "Save application log to this directory for reporting issues.",
Name: logger.LogFileFlag,
Usage: "Save application log to this file for reporting issues.",
},
&cli.StringFlag{
Name: logger.LogSSHDirectoryFlag,
Usage: "Save application log to this directory for reporting issues.",
},
&cli.StringFlag{
Name: logger.LogSSHLevelFlag,
@ -165,6 +169,11 @@ func Commands() []*cli.Command {
Hidden: true,
Usage: "Connect to alternate location for testing, value is host, host:port, or sni:port:host",
},
&cli.Uint64Flag{
Name: sshDebugStream,
Hidden: true,
Usage: "Writes up-to the max provided stream payloads to the logger as debug statements.",
},
},
},
{

View File

@ -175,7 +175,7 @@ func createFromContext(
log := newZerolog(loggerConfig)
if incompatibleFlagsSet := logFile != "" && logDirectory != ""; incompatibleFlagsSet {
log.Error().Msgf("Your config includes values for both %s and %s, but they are incompatible. %s takes precedence.", LogFileFlag, logDirectoryFlagName, LogFileFlag)
log.Error().Msgf("Your config includes values for both %s (%s) and %s (%s), but they are incompatible. %s takes precedence.", LogFileFlag, logFile, logDirectoryFlagName, logDirectory, LogFileFlag)
}
return log
}

64
stream/debug.go Normal file
View File

@ -0,0 +1,64 @@
package stream
import (
"io"
"sync/atomic"
"github.com/rs/zerolog"
)
// DebugStream will tee each read and write to the output logger as a debug message
type DebugStream struct {
reader io.Reader
writer io.Writer
log *zerolog.Logger
max uint64
count atomic.Uint64
}
func NewDebugStream(stream io.ReadWriter, logger *zerolog.Logger, max uint64) *DebugStream {
return &DebugStream{
reader: stream,
writer: stream,
log: logger,
max: max,
}
}
func (d *DebugStream) Read(p []byte) (n int, err error) {
n, err = d.reader.Read(p)
if n > 0 && d.max > d.count.Load() {
d.count.Add(1)
if err != nil {
d.log.Err(err).
Str("dir", "r").
Int("count", n).
Msgf("%+q", p[:n])
} else {
d.log.Debug().
Str("dir", "r").
Int("count", n).
Msgf("%+q", p[:n])
}
}
return
}
func (d *DebugStream) Write(p []byte) (n int, err error) {
n, err = d.writer.Write(p)
if n > 0 && d.max > d.count.Load() {
d.count.Add(1)
if err != nil {
d.log.Err(err).
Str("dir", "w").
Int("count", n).
Msgf("%+q", p[:n])
} else {
d.log.Debug().
Str("dir", "w").
Int("count", n).
Msgf("%+q", p[:n])
}
}
return
}