xcode: allow ICMP ping relay on macOS + iOS platforms (#12048)

Fixes tailscale/tailscale#10393
Fixes tailscale/corp#15412
Fixes tailscale/corp#19808

On Apple platforms, exit nodes and subnet routers have been unable to relay pings from Tailscale devices to non-Tailscale devices due to sandbox restrictions imposed on our network extensions by Apple. The sandbox prevented the code in netstack.go from spawning the `ping` process which we were using.

Replace that exec call with logic to send an ICMP echo request directly, which appears to work in userspace, and not trigger a sandbox violation in the syslog.

Signed-off-by: Andrea Gottardo <andrea@gottardo.me>
This commit is contained in:
Andrea Gottardo 2024-05-16 11:57:57 -07:00 committed by GitHub
parent 59848fe14b
commit e5f67f90a2
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
6 changed files with 114 additions and 51 deletions

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@ -144,6 +144,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
L github.com/pierrec/lz4/v4/internal/xxh32 from github.com/pierrec/lz4/v4/internal/lz4stream
LD github.com/pkg/sftp from tailscale.com/ssh/tailssh
LD github.com/pkg/sftp/internal/encoding/ssh/filexfer from github.com/pkg/sftp
D github.com/prometheus-community/pro-bing from tailscale.com/wgengine/netstack
L 💣 github.com/safchain/ethtool from tailscale.com/net/netkernelconf+
W 💣 github.com/tailscale/certstore from tailscale.com/control/controlclient
W 💣 github.com/tailscale/go-winio from tailscale.com/safesocket
@ -439,7 +440,7 @@ tailscale.com/cmd/tailscaled dependencies: (generated by github.com/tailscale/de
golang.org/x/net/http2 from golang.org/x/net/http2/h2c+
golang.org/x/net/http2/h2c from tailscale.com/ipn/ipnlocal
golang.org/x/net/http2/hpack from golang.org/x/net/http2+
golang.org/x/net/icmp from tailscale.com/net/ping
golang.org/x/net/icmp from tailscale.com/net/ping+
golang.org/x/net/idna from golang.org/x/net/http/httpguts+
golang.org/x/net/ipv4 from github.com/miekg/dns+
golang.org/x/net/ipv6 from github.com/miekg/dns+

3
go.mod
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@ -37,7 +37,7 @@ require (
github.com/google/go-cmp v0.6.0
github.com/google/go-containerregistry v0.18.0
github.com/google/nftables v0.2.1-0.20240414091927-5e242ec57806
github.com/google/uuid v1.5.0
github.com/google/uuid v1.6.0
github.com/goreleaser/nfpm/v2 v2.33.1
github.com/hdevalence/ed25519consensus v0.2.0
github.com/iancoleman/strcase v0.3.0
@ -60,6 +60,7 @@ require (
github.com/peterbourgon/ff/v3 v3.4.0
github.com/pkg/errors v0.9.1
github.com/pkg/sftp v1.13.6
github.com/prometheus-community/pro-bing v0.4.0
github.com/prometheus/client_golang v1.18.0
github.com/prometheus/common v0.46.0
github.com/safchain/ethtool v0.3.0

6
go.sum
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@ -468,8 +468,8 @@ github.com/google/rpmpack v0.5.0 h1:L16KZ3QvkFGpYhmp23iQip+mx1X39foEsqszjMNBm8A=
github.com/google/rpmpack v0.5.0/go.mod h1:uqVAUVQLq8UY2hCDfmJ/+rtO3aw7qyhc90rCVEabEfI=
github.com/google/uuid v1.1.1/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
github.com/google/uuid v1.1.2/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
github.com/google/uuid v1.5.0 h1:1p67kYwdtXjb0gL0BPiP1Av9wiZPo5A8z2cWkTZ+eyU=
github.com/google/uuid v1.5.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
github.com/googleapis/gax-go/v2 v2.0.4/go.mod h1:0Wqv26UfaUD9n4G6kQubkQ+KchISgw+vpHVxEJEs9eg=
github.com/googleapis/gax-go/v2 v2.0.5/go.mod h1:DWXyrwAJ9X0FpwwEdw+IPEYBICEFu5mhpdKc/us6bOk=
github.com/googleapis/google-cloud-go-testing v0.0.0-20200911160855-bcd43fbb19e8/go.mod h1:dvDLG8qkwmyD9a/MJJN3XJcT3xFxOKAvTZGvuZmac9g=
@ -731,6 +731,8 @@ github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZb
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/polyfloyd/go-errorlint v1.4.1 h1:r8ru5FhXSn34YU1GJDOuoJv2LdsQkPmK325EOpPMJlM=
github.com/polyfloyd/go-errorlint v1.4.1/go.mod h1:k6fU/+fQe38ednoZS51T7gSIGQW1y94d6TkSr35OzH8=
github.com/prometheus-community/pro-bing v0.4.0 h1:YMbv+i08gQz97OZZBwLyvmmQEEzyfyrrjEaAchdy3R4=
github.com/prometheus-community/pro-bing v0.4.0/go.mod h1:b7wRYZtCcPmt4Sz319BykUU241rWLe1VFXyiyWK/dH4=
github.com/prometheus/client_golang v0.9.1/go.mod h1:7SWBe2y4D6OKWSNQJUaRYU/AaXPKyh/dDVn+NZz0KFw=
github.com/prometheus/client_golang v1.0.0/go.mod h1:db9x61etRT2tGnBNRi70OPL5FsnadC4Ky3P0J6CfImo=
github.com/prometheus/client_golang v1.7.1/go.mod h1:PY5Wy2awLA44sXw4AOSfFBetzPP4j5+D6mVACh+pe2M=

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@ -15,8 +15,6 @@
"math"
"net"
"net/netip"
"os"
"os/exec"
"runtime"
"strconv"
"sync"
@ -55,7 +53,6 @@
"tailscale.com/types/nettype"
"tailscale.com/util/clientmetric"
"tailscale.com/version"
"tailscale.com/version/distro"
"tailscale.com/wgengine"
"tailscale.com/wgengine/filter"
"tailscale.com/wgengine/magicsock"
@ -916,14 +913,8 @@ func (ns *Impl) shouldProcessInbound(p *packet.Parsed, t *tstun.Wrapper) bool {
return false
}
// setAmbientCapsRaw is non-nil on Linux for Synology, to run ping with
// CAP_NET_RAW from tailscaled's binary.
var setAmbientCapsRaw func(*exec.Cmd)
var userPingSem = syncs.NewSemaphore(20) // 20 child ping processes at once
var isSynology = runtime.GOOS == "linux" && distro.Get() == distro.Synology
type userPingDirection int
const (
@ -944,6 +935,8 @@ func (ns *Impl) shouldProcessInbound(p *packet.Parsed, t *tstun.Wrapper) bool {
// it bounds the number of pings going on at once. The idea is that
// people only use ping occasionally to see if their internet's working
// so this doesn't need to be great.
// On Apple platforms, this function doesn't run the ping command. Instead,
// it sends a non-privileged ping.
//
// The 'direction' parameter is used to determine where the response "pong"
// packet should be written, if the ping succeeds. See the documentation on the
@ -958,44 +951,7 @@ func (ns *Impl) userPing(dstIP netip.Addr, pingResPkt []byte, direction userPing
defer userPingSem.Release()
t0 := time.Now()
var err error
switch runtime.GOOS {
case "windows":
err = exec.Command("ping", "-n", "1", "-w", "3000", dstIP.String()).Run()
case "darwin", "freebsd":
// Note: 2000 ms is actually 1 second + 2,000
// milliseconds extra for 3 seconds total.
// See https://github.com/tailscale/tailscale/pull/3753 for details.
ping := "ping"
if dstIP.Is6() {
ping = "ping6"
}
err = exec.Command(ping, "-c", "1", "-W", "2000", dstIP.String()).Run()
case "openbsd":
ping := "ping"
if dstIP.Is6() {
ping = "ping6"
}
err = exec.Command(ping, "-c", "1", "-w", "3", dstIP.String()).Run()
case "android":
ping := "/system/bin/ping"
if dstIP.Is6() {
ping = "/system/bin/ping6"
}
err = exec.Command(ping, "-c", "1", "-w", "3", dstIP.String()).Run()
default:
ping := "ping"
if isSynology {
ping = "/bin/ping"
}
cmd := exec.Command(ping, "-c", "1", "-W", "3", dstIP.String())
if isSynology && os.Getuid() != 0 {
// On DSM7 we run as non-root and need to pass
// CAP_NET_RAW if our binary has it.
setAmbientCapsRaw(cmd)
}
err = cmd.Run()
}
err := ns.sendOutboundUserPing(dstIP, 3*time.Second)
d := time.Since(t0)
if err != nil {
if d < time.Second/2 {

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@ -0,0 +1,65 @@
// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
//go:build !darwin && !ios
package netstack
import (
"net/netip"
"os"
"os/exec"
"runtime"
"time"
"tailscale.com/version/distro"
)
// setAmbientCapsRaw is non-nil on Linux for Synology, to run ping with
// CAP_NET_RAW from tailscaled's binary.
var setAmbientCapsRaw func(*exec.Cmd)
var isSynology = runtime.GOOS == "linux" && distro.Get() == distro.Synology
// sendOutboundUserPing sends a non-privileged ICMP (or ICMPv6) ping to dstIP with the given timeout.
func (ns *Impl) sendOutboundUserPing(dstIP netip.Addr, timeout time.Duration) error {
var err error
switch runtime.GOOS {
case "windows":
err = exec.Command("ping", "-n", "1", "-w", "3000", dstIP.String()).Run()
case "freebsd":
// Note: 2000 ms is actually 1 second + 2,000
// milliseconds extra for 3 seconds total.
// See https://github.com/tailscale/tailscale/pull/3753 for details.
ping := "ping"
if dstIP.Is6() {
ping = "ping6"
}
err = exec.Command(ping, "-c", "1", "-W", "2000", dstIP.String()).Run()
case "openbsd":
ping := "ping"
if dstIP.Is6() {
ping = "ping6"
}
err = exec.Command(ping, "-c", "1", "-w", "3", dstIP.String()).Run()
case "android":
ping := "/system/bin/ping"
if dstIP.Is6() {
ping = "/system/bin/ping6"
}
err = exec.Command(ping, "-c", "1", "-w", "3", dstIP.String()).Run()
default:
ping := "ping"
if isSynology {
ping = "/bin/ping"
}
cmd := exec.Command(ping, "-c", "1", "-W", "3", dstIP.String())
if isSynology && os.Getuid() != 0 {
// On DSM7 we run as non-root and need to pass
// CAP_NET_RAW if our binary has it.
setAmbientCapsRaw(cmd)
}
err = cmd.Run()
}
return err
}

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@ -0,0 +1,38 @@
// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
//go:build darwin || ios
package netstack
import (
"net/netip"
"time"
"github.com/prometheus-community/pro-bing"
)
// sendOutboundUserPing sends a non-privileged ICMP (or ICMPv6) ping to dstIP with the given timeout.
func (ns *Impl) sendOutboundUserPing(dstIP netip.Addr, timeout time.Duration) error {
p, err := probing.NewPinger(dstIP.String())
if err != nil {
ns.logf("sendICMPPingToIP failed to create pinger: %v", err)
return err
}
p.Timeout = timeout
p.Count = 1
p.SetPrivileged(false)
p.OnSend = func(pkt *probing.Packet) {
ns.logf("sendICMPPingToIP: forwarding ping to %s:", p.Addr())
}
p.OnRecv = func(pkt *probing.Packet) {
ns.logf("sendICMPPingToIP: %d bytes pong from %s: icmp_seq=%d time=%v", pkt.Nbytes, pkt.IPAddr, pkt.Seq, pkt.Rtt)
}
p.OnFinish = func(stats *probing.Statistics) {
ns.logf("sendICMPPingToIP: done, %d replies received", stats.PacketsRecv)
}
return p.Run()
}