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processmon.go
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processmon.go
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// Package processmon is to manage and monitor remote enforcers.
package processmon
import (
"bufio"
"context"
"fmt"
"io"
"os"
"os/exec"
"path/filepath"
"strconv"
"strings"
"sync"
"syscall"
"time"
"go.aporeto.io/trireme-lib/controller/constants"
"go.aporeto.io/trireme-lib/controller/internal/enforcer/utils/rpcwrapper"
"go.aporeto.io/trireme-lib/controller/pkg/claimsheader"
"go.aporeto.io/trireme-lib/controller/pkg/env"
"go.aporeto.io/trireme-lib/controller/pkg/remoteenforcer"
"go.aporeto.io/trireme-lib/policy"
"go.aporeto.io/trireme-lib/utils/cache"
"go.aporeto.io/trireme-lib/utils/crypto"
"go.uber.org/zap"
)
const (
// netNSPath holds the directory to ensure ip netns command works
netNSPath = "/var/run/netns/"
processMonitorCacheName = "ProcessMonitorCache"
remoteEnforcerBuildName = "remoteenforcerd"
remoteEnforcerTempBuildPath = "/var/run/aporeto/tmp/bin/"
secretLength = 32
)
var (
// execCommand is to used to fake exec commands in tests.
execCommand = exec.Command
)
// RemoteMonitor is an instance of processMonitor
type RemoteMonitor struct {
// netNSPath made configurable to enable running tests
netNSPath string
// remoteEnforcerTempBuildPath made configurable to enable running tests
remoteEnforcerTempBuildPath string
// remoteEnforcerBuildName made configurable to enable running tests
remoteEnforcerBuildName string
// activeProcesses holds a cache of the currently active processes.
activeProcesses *cache.Cache
// childExitStatus is a channel to monitor the exit status of processes.
childExitStatus chan exitStatus
// logToConsole stores if we should log to console.
logToConsole bool
// logWithID is the ID for for log files if logging to file.
logWithID bool
// logLevel is the level of logs for remote command.
logLevel string
// logFormat selects the format of the logs for the remote.
logFormat string
// compressedTags instructs the remotes to use compressed tags.
compressedTags claimsheader.CompressionType
// runtimeErrorChannel is the channel to communicate errors to the policy engine.
runtimeErrorChannel chan *policy.RuntimeError
// rpc is the rpc client to communicate with the remotes.
rpc rpcwrapper.RPCClient
// DisableLogWrite flag tells if we are running in kubernetes.
DisableLogWrite bool
sync.Mutex
}
// processInfo stores per process information
type processInfo struct {
contextID string
process *os.Process
sync.Mutex
}
// exitStatus captures the exit status of a process
type exitStatus struct {
process int
// The contextID is optional and is primarily used by remote enforcer
// processes to represent the namespace in which the process was running
contextID string
exitStatus error
}
// New is a method to create a new remote process monitor.
func New(ctx context.Context, p *env.RemoteParameters, c chan *policy.RuntimeError, r rpcwrapper.RPCClient) ProcessManager {
m := &RemoteMonitor{
remoteEnforcerTempBuildPath: remoteEnforcerTempBuildPath,
remoteEnforcerBuildName: remoteEnforcerBuildName,
netNSPath: netNSPath,
activeProcesses: cache.NewCache(processMonitorCacheName),
childExitStatus: make(chan exitStatus, 100),
logToConsole: p.LogToConsole,
logWithID: p.LogWithID,
logLevel: p.LogLevel,
logFormat: p.LogFormat,
DisableLogWrite: p.DisableLogWrite,
compressedTags: p.CompressedTags,
runtimeErrorChannel: c,
rpc: r,
}
go m.collectChildExitStatus(ctx)
return m
}
// LaunchRemoteEnforcer prepares the environment and launches the process. If the process
// is already launched, it will notify the caller, so that it can avoid any
// new initialization.
func (p *RemoteMonitor) LaunchRemoteEnforcer(
contextID string,
refPid int,
refNSPath string,
arg string,
statsServerSecret string,
procMountPoint string,
) (bool, error) {
// Locking here to get the procesinfo to avoid race conditions
// where multiple LaunchProcess happen for the same context.
p.Lock()
if _, err := p.activeProcesses.Get(contextID); err == nil {
p.Unlock()
return false, nil
}
procInfo := &processInfo{
contextID: contextID,
}
p.activeProcesses.AddOrUpdate(contextID, procInfo)
p.Unlock()
// We will lock the procInfo here, so a kill will have to wait and avoid any race.
procInfo.Lock()
defer procInfo.Unlock()
var err error
defer func() {
// If we encoutered an error we remove it from the cache. We will
// not be monitoring it any more. Caller is responsible for re-launching.
if err != nil {
p.Lock()
defer p.Unlock()
p.activeProcesses.Remove(contextID) // nolint errcheck
}
}()
// We check if the NetNsPath was given as parameter.
// If it was we will use it. Otherwise we will determine it based on the PID.
nsPath := refNSPath
if refNSPath == "" {
nsPath = filepath.Join(procMountPoint, strconv.Itoa(refPid), "ns/net")
}
var hoststat os.FileInfo
if hoststat, err = os.Stat(filepath.Join(procMountPoint, "1/ns/net")); err != nil {
return false, err
}
var pidstat os.FileInfo
if pidstat, err = os.Stat(nsPath); err != nil {
return false, fmt.Errorf("container pid %d not found: %s", refPid, err)
}
if pidstat.Sys().(*syscall.Stat_t).Ino == hoststat.Sys().(*syscall.Stat_t).Ino {
err = fmt.Errorf("refused to launch a remote enforcer in host namespace")
return false, err
}
cmd := p.getLaunchProcessCmd(p.remoteEnforcerTempBuildPath, p.remoteEnforcerBuildName, arg)
if err = p.pollStdOutAndErr(cmd); err != nil {
return false, err
}
var randomkeystring string
randomkeystring, err = crypto.GenerateRandomString(secretLength)
if err != nil {
// This is a more serious failure. We can't reliably control the remote enforcer
return false, fmt.Errorf("unable to generate secret: %s", err)
}
// Start command
newEnvVars := p.getLaunchProcessEnvVars(
procMountPoint,
contextID,
randomkeystring,
statsServerSecret,
refPid,
refNSPath,
)
cmd.Env = append(os.Environ(), newEnvVars...)
if err = cmd.Start(); err != nil {
return false, fmt.Errorf("unable to start enforcer binary: %s", err)
}
procInfo.process = cmd.Process
if err = p.rpc.NewRPCClient(contextID, contextID2SocketPath(contextID), randomkeystring); err != nil {
return false, fmt.Errorf("failed to established rpc channel: %s", err)
}
go func() {
status := cmd.Wait()
p.childExitStatus <- exitStatus{
process: cmd.Process.Pid,
contextID: contextID,
exitStatus: status,
}
}()
return true, nil
}
// KillRemoteEnforcer sends a rpc to the process to exit failing which it will kill the process
func (p *RemoteMonitor) KillRemoteEnforcer(contextID string, force bool) error {
p.Lock()
s, err := p.activeProcesses.Get(contextID)
if err != nil {
p.Unlock()
return fmt.Errorf("unable to find process for context: %s", contextID)
}
p.activeProcesses.Remove(contextID) // nolint errcheck
p.Unlock()
procInfo, ok := s.(*processInfo)
if !ok {
return fmt.Errorf("internal error - invalid type for process")
}
procInfo.Lock()
defer procInfo.Unlock()
if procInfo.process == nil {
return fmt.Errorf("cannot find process for context: %s", contextID)
}
req := &rpcwrapper.Request{
Payload: procInfo.process.Pid,
}
resp := &rpcwrapper.Response{}
c := make(chan error, 1)
go func() {
c <- p.rpc.RemoteCall(contextID, remoteenforcer.EnforcerExit, req, resp)
}()
select {
case err := <-c:
if err != nil && force {
zap.L().Error("Failed to stop gracefully - forcing kill",
zap.Error(err))
procInfo.process.Kill() // nolint
}
case <-time.After(5 * time.Second):
if force {
zap.L().Error("Time out on terminating remote enforcer - forcing kill")
procInfo.process.Kill() // nolint
}
}
p.rpc.DestroyRPCClient(contextID)
return nil
}
// collectChildExitStatus is an async function which collects status for all launched child processes
func (p *RemoteMonitor) collectChildExitStatus(ctx context.Context) {
defer func() {
if r := recover(); r != nil {
zap.L().Error("Policy engine has possibly closed the channel")
return
}
}()
for {
select {
case <-ctx.Done():
return
case es := <-p.childExitStatus:
if err := p.activeProcesses.Remove(es.contextID); err != nil {
continue
}
p.rpc.DestroyRPCClient(es.contextID)
if p.runtimeErrorChannel != nil {
if es.exitStatus != nil {
zap.L().Error("Remote enforcer exited with an error",
zap.String("nativeContextID", es.contextID),
zap.Int("pid", es.process),
zap.Error(es.exitStatus),
)
} else {
zap.L().Warn("Remote enforcer exited",
zap.String("nativeContextID", es.contextID),
zap.Int("pid", es.process),
)
}
p.runtimeErrorChannel <- &policy.RuntimeError{
ContextID: es.contextID,
Error: fmt.Errorf("remote enforcer terminated: %s", es.exitStatus),
}
}
}
}
}
// pollStdOutAndErr polls std out and err
func (p *RemoteMonitor) pollStdOutAndErr(
cmd *exec.Cmd,
) (err error) {
stdout, err := cmd.StdoutPipe()
if err != nil {
return err
}
stderr, err := cmd.StderrPipe()
if err != nil {
return err
}
// Stdout/err processing
go processIOReader(stdout)
go processIOReader(stderr)
return nil
}
// getLaunchProcessCmd returns the command used to launch the enforcerd
func (p *RemoteMonitor) getLaunchProcessCmd(remoteEnforcerBuildPath, remoteEnforcerName, arg string) *exec.Cmd {
cmdName := filepath.Join(remoteEnforcerBuildPath, remoteEnforcerName)
cmdArgs := []string{arg}
zap.L().Debug("Enforcer executed",
zap.String("command", cmdName),
zap.Strings("args", cmdArgs),
)
return execCommand(cmdName, cmdArgs...)
}
// getLaunchProcessEnvVars returns a slice of env variable strings where each string is in the form of key=value
func (p *RemoteMonitor) getLaunchProcessEnvVars(
procMountPoint string,
contextID string,
randomkeystring string,
statsServerSecret string,
refPid int,
refNSPath string,
) []string {
disableLog := strconv.FormatBool(p.DisableLogWrite)
newEnvVars := []string{
constants.EnvMountPoint + "=" + procMountPoint,
constants.EnvContextSocket + "=" + contextID2SocketPath(contextID),
constants.EnvStatsChannel + "=" + constants.StatsChannel,
constants.EnvDebugChannel + "=" + constants.DebugChannel,
constants.EnvRPCClientSecret + "=" + randomkeystring,
constants.EnvStatsSecret + "=" + statsServerSecret,
constants.EnvContainerPID + "=" + strconv.Itoa(refPid),
constants.EnvLogLevel + "=" + p.logLevel,
constants.EnvLogFormat + "=" + p.logFormat,
constants.EnvDisableLogWrite + "=" + disableLog,
}
if p.compressedTags != claimsheader.CompressionTypeNone {
newEnvVars = append(newEnvVars, constants.EnvCompressedTags+"="+string(p.compressedTags))
}
if p.logToConsole {
newEnvVars = append(newEnvVars, constants.EnvLogToConsole+"="+constants.EnvLogToConsoleEnable)
}
if p.logWithID {
newEnvVars = append(newEnvVars, constants.EnvLogID+"="+contextID)
}
// If the PURuntime Specified a NSPath, then it is added as a new env var also.
if refNSPath != "" {
newEnvVars = append(newEnvVars, constants.EnvNSPath+"="+refNSPath)
}
return newEnvVars
}
// contextID2SocketPath returns the socket path to use for a givent context
func contextID2SocketPath(contextID string) string {
if contextID == "" {
panic("contextID is empty")
}
return filepath.Join("/var/run/", strings.Replace(contextID, "/", "_", -1)+".sock")
}
// processIOReader will read from a reader and print it on the calling process
func processIOReader(fd io.Reader) {
reader := bufio.NewReader(fd)
for {
str, err := reader.ReadString('\n')
if err != nil {
return
}
fmt.Print(str)
}
}