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// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package boot
import (
"fmt"
"os"
"sync"
"syscall"
"github.com/golang/protobuf/proto"
"gvisor.dev/gvisor/pkg/eventchannel"
"gvisor.dev/gvisor/pkg/log"
rpb "gvisor.dev/gvisor/pkg/sentry/arch/registers_go_proto"
ucspb "gvisor.dev/gvisor/pkg/sentry/kernel/uncaught_signal_go_proto"
"gvisor.dev/gvisor/pkg/sentry/strace"
spb "gvisor.dev/gvisor/pkg/sentry/unimpl/unimplemented_syscall_go_proto"
)
func initCompatLogs(fd int) error {
ce, err := newCompatEmitter(fd)
if err != nil {
return err
}
eventchannel.AddEmitter(ce)
return nil
}
type compatEmitter struct {
sink *log.BasicLogger
nameMap strace.SyscallMap
// mu protects the fields below.
mu sync.Mutex
// trackers map syscall number to the respective tracker instance.
// Protected by 'mu'.
trackers map[uint64]syscallTracker
}
func newCompatEmitter(logFD int) (*compatEmitter, error) {
nameMap, ok := getSyscallNameMap()
if !ok {
return nil, fmt.Errorf("Linux syscall table not found")
}
c := &compatEmitter{
// Always logs to default logger.
sink: log.Log(),
nameMap: nameMap,
trackers: make(map[uint64]syscallTracker),
}
if logFD > 0 {
f := os.NewFile(uintptr(logFD), "user log file")
target := log.MultiEmitter{c.sink, log.K8sJSONEmitter{log.Writer{Next: f}}}
c.sink = &log.BasicLogger{Level: log.Info, Emitter: target}
}
return c, nil
}
// Emit implements eventchannel.Emitter.
func (c *compatEmitter) Emit(msg proto.Message) (bool, error) {
switch m := msg.(type) {
case *spb.UnimplementedSyscall:
c.emitUnimplementedSyscall(m)
case *ucspb.UncaughtSignal:
c.emitUncaughtSignal(m)
}
return false, nil
}
func (c *compatEmitter) emitUnimplementedSyscall(us *spb.UnimplementedSyscall) {
regs := us.Registers
c.mu.Lock()
defer c.mu.Unlock()
sysnr := syscallNum(regs)
tr := c.trackers[sysnr]
if tr == nil {
switch sysnr {
case syscall.SYS_PRCTL:
// args: cmd, ...
tr = newArgsTracker(0)
case syscall.SYS_IOCTL, syscall.SYS_EPOLL_CTL, syscall.SYS_SHMCTL, syscall.SYS_FUTEX, syscall.SYS_FALLOCATE:
// args: fd/addr, cmd, ...
tr = newArgsTracker(1)
case syscall.SYS_GETSOCKOPT, syscall.SYS_SETSOCKOPT:
// args: fd, level, name, ...
tr = newArgsTracker(1, 2)
case syscall.SYS_SEMCTL:
// args: semid, semnum, cmd, ...
tr = newArgsTracker(2)
default:
tr = newArchArgsTracker(sysnr)
if tr == nil {
tr = &onceTracker{}
}
}
c.trackers[sysnr] = tr
}
if tr.shouldReport(regs) {
c.sink.Infof("Unsupported syscall: %s, regs: %+v", c.nameMap.Name(uintptr(sysnr)), regs)
tr.onReported(regs)
}
}
func (c *compatEmitter) emitUncaughtSignal(msg *ucspb.UncaughtSignal) {
sig := syscall.Signal(msg.SignalNumber)
c.sink.Infof(
"Uncaught signal: %q (%d), PID: %d, TID: %d, fault addr: %#x",
sig, msg.SignalNumber, msg.Pid, msg.Tid, msg.FaultAddr)
}
// Close implements eventchannel.Emitter.
func (c *compatEmitter) Close() error {
c.sink = nil
return nil
}
// syscallTracker interface allows filters to apply differently depending on
// the syscall and arguments.
type syscallTracker interface {
// shouldReport returns true is the syscall should be reported.
shouldReport(regs *rpb.Registers) bool
// onReported marks the syscall as reported.
onReported(regs *rpb.Registers)
}
// onceTracker reports only a single time, used for most syscalls.
type onceTracker struct {
reported bool
}
func (o *onceTracker) shouldReport(_ *rpb.Registers) bool {
return !o.reported
}
func (o *onceTracker) onReported(_ *rpb.Registers) {
o.reported = true
}
// argsTracker reports only once for each different combination of arguments.
// It's used for generic syscalls like ioctl to report once per 'cmd'.
type argsTracker struct {
// argsIdx is the syscall arguments to use as unique ID.
argsIdx []int
reported map[string]struct{}
count int
}
func newArgsTracker(argIdx ...int) *argsTracker {
return &argsTracker{argsIdx: argIdx, reported: make(map[string]struct{})}
}
// key returns the command based on the syscall argument index.
func (a *argsTracker) key(regs *rpb.Registers) string {
var rv string
for _, idx := range a.argsIdx {
rv += fmt.Sprintf("%d|", argVal(idx, regs))
}
return rv
}
func (a *argsTracker) shouldReport(regs *rpb.Registers) bool {
if a.count >= reportLimit {
return false
}
_, ok := a.reported[a.key(regs)]
return !ok
}
func (a *argsTracker) onReported(regs *rpb.Registers) {
a.count++
a.reported[a.key(regs)] = struct{}{}
}
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