1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
|
package main
import (
"bytes"
"encoding/binary"
"unsafe"
"fmt"
"os"
"os/signal"
"runtime"
"syscall"
"time"
)
type childOutput struct {
fd int
n int
buf []byte
}
func doParent(mpid int, stdin_fd, stdout_fd, stderr_fd [2]int) resultPack {
syscall.Close(stdin_fd[0])
syscall.Close(stdout_fd[1])
syscall.Close(stderr_fd[1])
exit_chan := make(chan resultPack)
if err := SetupScope(uint32(mpid)); err != nil {
poePanic(err, "setup systemd scope unit failed")
}
go func() {
runtime.LockOSThread()
sig_chan := make(chan os.Signal, 1)
signal.Notify(sig_chan, syscall.SIGCHLD)
signal.Notify(sig_chan, syscall.SIGTERM)
signal.Notify(sig_chan, syscall.SIGINT)
if err := PtraceSeize(mpid, syscall.PTRACE_O_TRACECLONE|syscall.PTRACE_O_TRACEFORK|PTRACE_O_TRACESECCOMP|syscall.PTRACE_O_TRACEVFORK); err != nil {
poePanic(error(err), "PTRACE_SEIZE failed")
}
for {
sig := <-sig_chan
switch sig {
case syscall.SIGCHLD:
if res := handleSigchld(mpid); res != nil {
exit_chan <- *res
}
case syscall.SIGTERM, syscall.SIGINT:
exit_chan <- resultPack{POE_TIMEDOUT, -1, "Supervisor terminated"}
}
}
}()
// TODO: output order is not preserved
out_chan := make(chan childOutput, 1)
go func() {
epfd, err := syscall.EpollCreate1(0)
if err != nil {
poePanic(err, "epoll_create1 failed")
}
defer syscall.Close(epfd)
event1 := syscall.EpollEvent{Events: syscall.EPOLLIN, Fd: int32(stdout_fd[0]), Pad: 1} // Fd/Pad is epoll_data_t (userdata)
if err := syscall.EpollCtl(epfd, syscall.EPOLL_CTL_ADD, stdout_fd[0], &event1); err != nil {
poePanic(err, "epoll_ctl (EPOLL_CTL_ADD) failed")
}
event2 := syscall.EpollEvent{Events: syscall.EPOLLIN, Fd: int32(stderr_fd[0]), Pad: 2}
if err := syscall.EpollCtl(epfd, syscall.EPOLL_CTL_ADD, stderr_fd[0], &event2); err != nil {
poePanic(err, "epoll_ctl (EPOLL_CTL_ADD) failed")
}
var events [32]syscall.EpollEvent
for {
en, err := syscall.EpollWait(epfd, events[:], -1)
if err != nil {
poePanic(err, "epoll_wait failed")
}
var buf [65536]byte // TODO: how to get PIPE_BUF?
for ev := 0; ev < en; ev++ {
for {
r1, _, e1 := syscall.Syscall(syscall.SYS_READ, uintptr(events[ev].Fd), uintptr(unsafe.Pointer(&buf[0])), uintptr(len(buf)))
if e1 != 0 {
break
}
n := int(r1)
if r1 > 0 {
nbuf := make([]byte, n)
copy(nbuf, buf[:n])
out_chan <- childOutput{int(events[ev].Pad), n, nbuf}
}
}
}
}
}()
go func() {
for {
out := <-out_chan
var outbuf bytes.Buffer
binary.Write(&outbuf, binary.LittleEndian, int32(out.fd))
binary.Write(&outbuf, binary.LittleEndian, int32(out.n))
if _, err := os.Stdout.Write(outbuf.Bytes()); err != nil {
poePanic(err, "stdout write failed")
}
if _, err := os.Stdout.Write(out.buf); err != nil {
poePanic(err, "stdout write failed")
}
}
}()
go func() {
<-time.After(3 * time.Second)
exit_chan <- resultPack{POE_TIMEDOUT, -1, ""}
}()
if _, err := syscall.Write(stdin_fd[1], []byte{0}); err != nil {
poePanic(err, "write to stdin failed")
}
return <-exit_chan
}
func handleSigchld(mpid int) *resultPack {
for {
var status syscall.WaitStatus
var spid int
var err error
spid, err = syscall.Wait4(-mpid, &status, syscall.WNOHANG|syscall.WALL, nil)
if err != nil {
poePanic(err, "wait4 failed")
} else if spid == 0 {
return nil
}
if spid == mpid && status.Exited() {
return &resultPack{POE_SUCCESS, status.ExitStatus(), ""}
} else if spid == mpid && status.Signaled() {
return &resultPack{POE_SIGNALED, -1, fmt.Sprintf("Program terminated with signal %d (%s)", int(status.Signal()), status.Signal().String())}
} else if status.Stopped() {
e := status >> 16 & 0xff
switch e {
case PTRACE_EVENT_SECCOMP:
if res := handleSyscall(spid); res != nil {
return res
}
case syscall.PTRACE_EVENT_CLONE, syscall.PTRACE_EVENT_FORK, syscall.PTRACE_EVENT_VFORK:
syscall.PtraceCont(spid, 0)
default:
syscall.PtraceCont(spid, int(status.StopSignal()))
}
}
}
}
func handleSyscall(spid int) *resultPack {
var regs syscall.PtraceRegs
if err := syscall.PtraceGetRegs(spid, ®s); err != nil {
poePanic(err, "getreg failed")
}
switch regs.Orig_rax {
case syscall.SYS_KILL:
goto allow
default:
goto kill
}
kill:
if err := syscall.Kill(spid, syscall.SIGKILL); err != nil {
poePanic(err, "failed to kill process which called prohibited syscall")
} else if name, err := ResolveSeccompSyscallName(regs.Orig_rax); err != nil {
poePanic(err, "seccomp_syscall_resolve_num_arch() failed")
} else {
return &resultPack{POE_SIGNALED, -1, fmt.Sprintf("System call %s is blocked", name)}
}
allow:
if err := syscall.PtraceCont(spid, 0); err != nil {
poePanic(err, "PTRACE_CONT failed")
}
return nil
}
|
