go-sandbox/container/container_exec_linux.go

188 lines
4.3 KiB
Go

package container
import (
"fmt"
"syscall"
"time"
"github.com/criyle/go-sandbox/pkg/forkexec"
"github.com/criyle/go-sandbox/pkg/unixsocket"
"github.com/criyle/go-sandbox/runner"
)
func (c *containerServer) handleExecve(cmd *execCmd, msg *unixsocket.Msg) error {
var (
files []uintptr
execFile uintptr
cred *syscall.Credential
)
if cmd == nil {
return c.sendErrorReply("execve: no parameter provided")
}
if msg != nil {
files = intSliceToUintptr(msg.Fds)
// don't leak fds to child
closeOnExecFds(msg.Fds)
// release files after execve
defer closeFds(msg.Fds)
}
// if fexecve, then the first fd must be executable
if cmd.FdExec {
if len(files) == 0 {
return fmt.Errorf("execve: expected fexecve fd")
}
execFile = files[0]
files = files[1:]
}
syncFunc := func(pid int) error {
msg := &unixsocket.Msg{
Cred: &syscall.Ucred{
Pid: int32(pid),
Uid: uint32(syscall.Getuid()),
Gid: uint32(syscall.Getgid()),
},
}
if err := c.sendReply(&reply{}, msg); err != nil {
return fmt.Errorf("syncFunc: sendReply %v", err)
}
cmd, _, err := c.recvCmd()
if err != nil {
return fmt.Errorf("syncFunc: recvCmd %v", err)
}
if cmd.Cmd == cmdKill {
return fmt.Errorf("syncFunc: received kill")
}
return nil
}
if c.Cred {
cred = &syscall.Credential{
Uid: uint32(c.ContainerUID),
Gid: uint32(c.ContainerGID),
NoSetGroups: true,
}
}
var seccomp *syscall.SockFprog
if cmd.Seccomp != nil {
seccomp = cmd.Seccomp.SockFprog()
}
r := forkexec.Runner{
Args: cmd.Argv,
Env: cmd.Env,
ExecFile: execFile,
RLimits: cmd.RLimits,
Files: files,
WorkDir: c.WorkDir,
NoNewPrivs: true,
DropCaps: true,
SyncFunc: syncFunc,
Credential: cred,
CTTY: cmd.CTTY,
Seccomp: seccomp,
UnshareCgroupAfterSync: true,
}
// starts the runner, error is handled same as wait4 to make communication equal
pid, err := r.Start()
if err != nil {
// cannot exists now since host assumes the start will alway work
err = fmt.Errorf("execve: start: %v", err)
}
return c.handleExecveStarted(pid, err)
}
func (c *containerServer) handleExecveStarted(pid int, err error) error {
// done is to signal kill goroutine exits
killDone := make(chan struct{})
// waitDone is to signal kill goroutine to collect zombies
waitDone := make(chan struct{})
// recv kill
go func() {
// signal done
defer close(killDone)
// msg must be kill
c.recvCmd()
// kill all
syscall.Kill(-1, syscall.SIGKILL)
// make sure collect zombie does not consume the exit status
<-waitDone
// collect zombies
for {
if _, err := syscall.Wait4(-1, nil, syscall.WNOHANG, nil); err != nil && err != syscall.EINTR {
break
}
}
}()
// wait pid if no error encountered for execve
var wstatus syscall.WaitStatus
var rusage syscall.Rusage
if err == nil {
_, err = syscall.Wait4(pid, &wstatus, 0, &rusage)
for err == syscall.EINTR {
_, err = syscall.Wait4(pid, &wstatus, 0, &rusage)
}
if err != nil {
err = fmt.Errorf("execve: wait4: %v", err)
}
}
// sync with kill goroutine
close(waitDone)
if err != nil {
c.sendErrorReply(err.Error())
} else {
status := runner.StatusNormal
userTime := time.Duration(rusage.Utime.Nano()) // ns
userMem := runner.Size(rusage.Maxrss << 10) // bytes
switch {
case wstatus.Exited():
exitStatus := wstatus.ExitStatus()
if exitStatus != 0 {
status = runner.StatusNonzeroExitStatus
}
c.sendReply(&reply{
ExecReply: &execReply{
Status: status,
ExitStatus: exitStatus,
Time: userTime,
Memory: userMem,
},
}, nil)
case wstatus.Signaled():
switch wstatus.Signal() {
// kill signal treats as TLE
case syscall.SIGXCPU, syscall.SIGKILL:
status = runner.StatusTimeLimitExceeded
case syscall.SIGXFSZ:
status = runner.StatusOutputLimitExceeded
case syscall.SIGSYS:
status = runner.StatusDisallowedSyscall
default:
status = runner.StatusSignalled
}
c.sendReply(&reply{
ExecReply: &execReply{
ExitStatus: int(wstatus.Signal()),
Status: status,
Time: userTime,
Memory: userMem,
},
}, nil)
default:
c.sendErrorReply("execve: unknown status %v", wstatus)
}
}
// wait for kill msg and reply done for finish
<-killDone
return c.sendReply(&reply{}, nil)
}