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|
package sshd
import (
"context"
"errors"
"fmt"
"reflect"
"gitlab.com/gitlab-org/labkit/log"
"golang.org/x/crypto/ssh"
shellCmd "gitlab.com/gitlab-org/gitlab-shell/cmd/gitlab-shell/command"
"gitlab.com/gitlab-org/gitlab-shell/internal/command/readwriter"
"gitlab.com/gitlab-org/gitlab-shell/internal/command/shared/disallowedcommand"
"gitlab.com/gitlab-org/gitlab-shell/internal/config"
"gitlab.com/gitlab-org/gitlab-shell/internal/sshenv"
)
type session struct {
// State set up by the connection
cfg *config.Config
channel ssh.Channel
gitlabKeyId string
remoteAddr string
success bool
// State managed by the session
execCmd string
gitProtocolVersion string
}
type execRequest struct {
Command string
}
type envRequest struct {
Name string
Value string
}
type exitStatusReq struct {
ExitStatus uint32
}
func (s *session) handle(ctx context.Context, requests <-chan *ssh.Request) {
ctxlog := log.ContextLogger(ctx)
ctxlog.Debug("session: handle: entering request loop")
for req := range requests {
sessionLog := ctxlog.WithFields(log.Fields{
"bytesize": len(req.Payload),
"type": req.Type,
"want_reply": req.WantReply,
})
sessionLog.Debug("session: handle: request received")
var shouldContinue bool
switch req.Type {
case "env":
shouldContinue = s.handleEnv(ctx, req)
case "exec":
shouldContinue = s.handleExec(ctx, req)
case "shell":
shouldContinue = false
s.exit(ctx, s.handleShell(ctx, req))
default:
// Ignore unknown requests but don't terminate the session
shouldContinue = true
if req.WantReply {
if err := req.Reply(false, []byte{}); err != nil {
sessionLog.WithError(err).Debug("session: handle: Failed to reply")
}
}
}
sessionLog.WithField("should_continue", shouldContinue).Debug("session: handle: request processed")
if !shouldContinue {
s.channel.Close()
break
}
}
ctxlog.Debug("session: handle: exiting request loop")
}
func (s *session) handleEnv(ctx context.Context, req *ssh.Request) bool {
var accepted bool
var envRequest envRequest
if err := ssh.Unmarshal(req.Payload, &envRequest); err != nil {
log.ContextLogger(ctx).WithError(err).Error("session: handleEnv: failed to unmarshal request")
return false
}
switch envRequest.Name {
case sshenv.GitProtocolEnv:
s.gitProtocolVersion = envRequest.Value
accepted = true
default:
// Client requested a forbidden envvar, nothing to do
}
if req.WantReply {
if err := req.Reply(accepted, []byte{}); err != nil {
log.ContextLogger(ctx).WithError(err).Debug("session: handleEnv: Failed to reply")
}
}
log.WithContextFields(
ctx, log.Fields{"accepted": accepted, "env_request": envRequest},
).Debug("session: handleEnv: processed")
return true
}
func (s *session) handleExec(ctx context.Context, req *ssh.Request) bool {
var execRequest execRequest
if err := ssh.Unmarshal(req.Payload, &execRequest); err != nil {
return false
}
s.execCmd = execRequest.Command
s.exit(ctx, s.handleShell(ctx, req))
return false
}
func (s *session) handleShell(ctx context.Context, req *ssh.Request) uint32 {
ctxlog := log.ContextLogger(ctx)
if req.WantReply {
if err := req.Reply(true, []byte{}); err != nil {
ctxlog.WithError(err).Debug("session: handleShell: Failed to reply")
}
}
env := sshenv.Env{
IsSSHConnection: true,
OriginalCommand: s.execCmd,
GitProtocolVersion: s.gitProtocolVersion,
RemoteAddr: s.remoteAddr,
}
rw := &readwriter.ReadWriter{
Out: s.channel,
In: s.channel,
ErrOut: s.channel.Stderr(),
}
cmd, err := shellCmd.NewWithKey(s.gitlabKeyId, env, s.cfg, rw)
if err != nil {
if !errors.Is(err, disallowedcommand.Error) {
s.toStderr(ctx, "Failed to parse command: %v\n", err.Error())
}
s.toStderr(ctx, "Unknown command: %v\n", s.execCmd)
return 128
}
cmdName := reflect.TypeOf(cmd).String()
ctxlog.WithFields(log.Fields{"env": env, "command": cmdName}).Info("session: handleShell: executing command")
if err := cmd.Execute(ctx); err != nil {
s.toStderr(ctx, "remote: ERROR: %v\n", err.Error())
return 1
}
ctxlog.Info("session: handleShell: command executed successfully")
return 0
}
func (s *session) toStderr(ctx context.Context, format string, args ...interface{}) {
out := fmt.Sprintf(format, args...)
log.WithContextFields(ctx, log.Fields{"stderr": out}).Debug("session: toStderr: output")
fmt.Fprint(s.channel.Stderr(), out)
}
func (s *session) exit(ctx context.Context, status uint32) {
log.WithContextFields(ctx, log.Fields{"exit_status": status}).Info("session: exit: exiting")
req := exitStatusReq{ExitStatus: status}
s.success = status == 0
s.channel.CloseWrite()
s.channel.SendRequest("exit-status", false, ssh.Marshal(req))
}
|
