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netstat, portlist: update Windows implementation to disambiguate svchost processes

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We change our invocations of GetExtendedTcpTable to request additional
information about the "module" responsible for the port. In addition to pid,
this output also includes sufficient metadata to enable Windows to resolve
process names and disambiguate svchost processes.

We store the OS-specific output in an OSMetadata field in netstat.Entry, which
portlist may then use as necessary to actually resolve the process/module name.

Signed-off-by: Aaron Klotz <aaron@tailscale.com>
This commit is contained in:
Aaron Klotz 2022-11-18 13:09:01 -07:00
parent a06217a8bd
commit 296f53524c
4 changed files with 152 additions and 85 deletions
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1
net/netstat/netstat.go
View File

@ -17,6 +17,7 @@ type Entry struct {
Local, Remote netip.AddrPort
Pid int
State string // TODO: type?
OSMetadata OSMetadata
}
// Table contains local machine's TCP connection entries.

4
net/netstat/netstat_noimpl.go
View File

@ -6,6 +6,10 @@
package netstat
// OSMetadata includes any additional OS-specific information that may be
// obtained during the retrieval of a given Entry.
type OSMetadata struct{}
func get() (*Table, error) {
return nil, ErrNotImplemented
}

193
net/netstat/netstat_windows.go
View File

@ -10,7 +10,6 @@
"fmt"
"math/bits"
"net/netip"
"syscall"
"unsafe"
"github.com/josharian/native"
@ -18,37 +17,99 @@
"tailscale.com/net/netaddr"
)
// OSMetadata includes any additional OS-specific information that may be
// obtained during the retrieval of a given Entry.
type OSMetadata interface {
GetModule() (string, error)
}
// See https://docs.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-getextendedtcptable
// TCP_TABLE_OWNER_PID_ALL means to include the PID info. The table type
// TCP_TABLE_OWNER_MODULE_ALL means to include the PID and module. The table type
// we get back from Windows depends on AF_INET vs AF_INET6:
// MIB_TCPTABLE_OWNER_PID for v4 or MIB_TCP6TABLE_OWNER_PID for v6.
const tcpTableOwnerPidAll = 5
// MIB_TCPTABLE_OWNER_MODULE for v4 or MIB_TCP6TABLE_OWNER_MODULE for v6.
const tcpTableOwnerModuleAll = 8
// TCPIP_OWNER_MODULE_BASIC_INFO means to request "basic information" about the
// owner module.
const tcpipOwnerModuleBasicInfo = 0
var (
iphlpapi = syscall.NewLazyDLL("iphlpapi.dll")
getTCPTable = iphlpapi.NewProc("GetExtendedTcpTable")
iphlpapi = windows.NewLazySystemDLL("iphlpapi.dll")
getTCPTable = iphlpapi.NewProc("GetExtendedTcpTable")
getOwnerModuleFromTcpEntry = iphlpapi.NewProc("GetOwnerModuleFromTcpEntry")
getOwnerModuleFromTcp6Entry = iphlpapi.NewProc("GetOwnerModuleFromTcp6Entry")
// TODO: GetExtendedUdpTable also? if/when needed.
)
type _MIB_TCPROW_OWNER_PID struct {
state uint32
localAddr uint32
localPort uint32
remoteAddr uint32
remotePort uint32
pid uint32
// See https://web.archive.org/web/20221219211913/https://learn.microsoft.com/en-us/windows/win32/api/tcpmib/ns-tcpmib-mib_tcprow_owner_module
type _MIB_TCPROW_OWNER_MODULE struct {
state uint32
localAddr uint32
localPort uint32
remoteAddr uint32
remotePort uint32
pid uint32
createTimestamp int64
owningModuleInfo [16]uint64
}
type _MIB_TCP6ROW_OWNER_PID struct {
localAddr [16]byte
localScope uint32
localPort uint32
remoteAddr [16]byte
remoteScope uint32
remotePort uint32
state uint32
pid uint32
func (row *_MIB_TCPROW_OWNER_MODULE) asEntry() Entry {
return Entry{
Local: ipport4(row.localAddr, port(&row.localPort)),
Remote: ipport4(row.remoteAddr, port(&row.remotePort)),
Pid: int(row.pid),
State: state(row.state),
OSMetadata: row,
}
}
type _MIB_TCPTABLE_OWNER_MODULE struct {
numEntries uint32
table _MIB_TCPROW_OWNER_MODULE
}
func (m *_MIB_TCPTABLE_OWNER_MODULE) getRows() []_MIB_TCPROW_OWNER_MODULE {
return unsafe.Slice(&m.table, m.numEntries)
}
// See https://web.archive.org/web/20221219212442/https://learn.microsoft.com/en-us/windows/win32/api/tcpmib/ns-tcpmib-mib_tcp6row_owner_module
type _MIB_TCP6ROW_OWNER_MODULE struct {
localAddr [16]byte
localScope uint32
localPort uint32
remoteAddr [16]byte
remoteScope uint32
remotePort uint32
state uint32
pid uint32
createTimestamp int64
owningModuleInfo [16]uint64
}
func (row *_MIB_TCP6ROW_OWNER_MODULE) asEntry() Entry {
return Entry{
Local: ipport6(row.localAddr, row.localScope, port(&row.localPort)),
Remote: ipport6(row.remoteAddr, row.remoteScope, port(&row.remotePort)),
Pid: int(row.pid),
State: state(row.state),
OSMetadata: row,
}
}
type _MIB_TCP6TABLE_OWNER_MODULE struct {
numEntries uint32
table _MIB_TCP6ROW_OWNER_MODULE
}
func (m *_MIB_TCP6TABLE_OWNER_MODULE) getRows() []_MIB_TCP6ROW_OWNER_MODULE {
return unsafe.Slice(&m.table, m.numEntries)
}
// See https://web.archive.org/web/20221219213143/https://learn.microsoft.com/en-us/windows/win32/api/iprtrmib/ns-iprtrmib-tcpip_owner_module_basic_info
type _TCPIP_OWNER_MODULE_BASIC_INFO struct {
moduleName *uint16
modulePath *uint16
}
func get() (*Table, error) {
@ -72,13 +133,13 @@ func (t *Table) addEntries(fam int) error {
uintptr(unsafe.Pointer(&size)),
1, // sorted
uintptr(fam),
tcpTableOwnerPidAll,
tcpTableOwnerModuleAll,
0, // reserved; "must be zero"
)
if err == 0 {
break
}
if err == uintptr(syscall.ERROR_INSUFFICIENT_BUFFER) {
if err == uintptr(windows.ERROR_INSUFFICIENT_BUFFER) {
const maxSize = 10 << 20
if size > maxSize || size < 4 {
return fmt.Errorf("unreasonable kernel-reported size %d", size)
@ -87,48 +148,28 @@ func (t *Table) addEntries(fam int) error {
addr = unsafe.Pointer(&buf[0])
continue
}
return syscall.Errno(err)
return windows.Errno(err)
}
if len(buf) < int(size) {
return errors.New("unexpected size growth from system call")
}
buf = buf[:size]
numEntries := native.Endian.Uint32(buf[:4])
buf = buf[4:]
var recSize int
switch fam {
case windows.AF_INET:
recSize = 6 * 4
case windows.AF_INET6:
recSize = 6*4 + 16*2
}
dataLen := numEntries * uint32(recSize)
if uint32(len(buf)) > dataLen {
buf = buf[:dataLen]
}
for len(buf) >= recSize {
switch fam {
case windows.AF_INET:
row := (*_MIB_TCPROW_OWNER_PID)(unsafe.Pointer(&buf[0]))
t.Entries = append(t.Entries, Entry{
Local: ipport4(row.localAddr, port(&row.localPort)),
Remote: ipport4(row.remoteAddr, port(&row.remotePort)),
Pid: int(row.pid),
State: state(row.state),
})
case windows.AF_INET6:
row := (*_MIB_TCP6ROW_OWNER_PID)(unsafe.Pointer(&buf[0]))
t.Entries = append(t.Entries, Entry{
Local: ipport6(row.localAddr, row.localScope, port(&row.localPort)),
Remote: ipport6(row.remoteAddr, row.remoteScope, port(&row.remotePort)),
Pid: int(row.pid),
State: state(row.state),
})
info := (*_MIB_TCPTABLE_OWNER_MODULE)(unsafe.Pointer(&buf[0]))
rows := info.getRows()
for _, row := range rows {
t.Entries = append(t.Entries, row.asEntry())
}
case windows.AF_INET6:
info := (*_MIB_TCP6TABLE_OWNER_MODULE)(unsafe.Pointer(&buf[0]))
rows := info.getRows()
for _, row := range rows {
t.Entries = append(t.Entries, row.asEntry())
}
buf = buf[recSize:]
}
return nil
}
@ -178,3 +219,43 @@ func port(v *uint32) uint16 {
}
return uint16(*v >> 16)
}
type moduleInfoConstraint interface {
_MIB_TCPROW_OWNER_MODULE | _MIB_TCP6ROW_OWNER_MODULE
}
func moduleInfo[entryType moduleInfoConstraint](entry *entryType, proc *windows.LazyProc) (string, error) {
var buf []byte
var desiredLen uint32
var addr unsafe.Pointer
for {
e, _, _ := proc.Call(
uintptr(unsafe.Pointer(entry)),
uintptr(tcpipOwnerModuleBasicInfo),
uintptr(addr),
uintptr(unsafe.Pointer(&desiredLen)),
)
err := windows.Errno(e)
if err == windows.ERROR_SUCCESS {
break
}
if err != windows.ERROR_INSUFFICIENT_BUFFER {
return "", err
}
buf = make([]byte, desiredLen)
addr = unsafe.Pointer(&buf[0])
}
basicInfo := (*_TCPIP_OWNER_MODULE_BASIC_INFO)(addr)
return windows.UTF16PtrToString(basicInfo.moduleName), nil
}
func (m *_MIB_TCPROW_OWNER_MODULE) GetModule() (string, error) {
return moduleInfo(m, getOwnerModuleFromTcpEntry)
}
func (m *_MIB_TCP6ROW_OWNER_MODULE) GetModule() (string, error) {
return moduleInfo(m, getOwnerModuleFromTcp6Entry)
}

39
portlist/portlist_windows.go
View File

@ -5,12 +5,8 @@
package portlist
import (
"path/filepath"
"strings"
"syscall"
"time"
"golang.org/x/sys/windows"
"tailscale.com/net/netstat"
)
@ -26,7 +22,7 @@ func init() {
type famPort struct {
proto string
port uint16
pid uintptr
pid uint32
}
type windowsImpl struct {
@ -69,19 +65,25 @@ func (im *windowsImpl) AppendListeningPorts(base []Port) ([]Port, error) {
fp := famPort{
proto: "tcp", // TODO(bradfitz): UDP too; add to netstat
port: e.Local.Port(),
pid: uintptr(e.Pid),
pid: uint32(e.Pid),
}
pm, ok := im.known[fp]
if ok {
pm.keep = true
continue
}
var process string
if e.OSMetadata != nil {
if module, err := e.OSMetadata.GetModule(); err == nil {
process = module
}
}
pm = &portMeta{
keep: true,
port: Port{
Proto: "tcp",
Port: e.Local.Port(),
Process: procNameOfPid(e.Pid),
Process: process,
},
}
im.known[fp] = pm
@ -94,27 +96,6 @@ func (im *windowsImpl) AppendListeningPorts(base []Port) ([]Port, error) {
}
ret = append(ret, m.port)
}
return sortAndDedup(ret), nil
}
func procNameOfPid(pid int) string {
const da = windows.PROCESS_QUERY_LIMITED_INFORMATION
h, err := syscall.OpenProcess(da, false, uint32(pid))
if err != nil {
return ""
}
defer syscall.CloseHandle(h)
var buf [512]uint16
var size = uint32(len(buf))
if err := windows.QueryFullProcessImageName(windows.Handle(h), 0, &buf[0], &size); err != nil {
return ""
}
name := filepath.Base(windows.UTF16ToString(buf[:]))
if name == "." {
return ""
}
name = strings.TrimSuffix(name, ".exe")
name = strings.TrimSuffix(name, ".EXE")
return name
}