1 files changed, 159 insertions, 0 deletions
diff --git a/runsc/boot/compat.go b/runsc/boot/compat.go
new file mode 100644
index 000000000..c369e4d64
--- /dev/null
+++ b/runsc/boot/compat.go
@@ -0,0 +1,159 @@
+// 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.googlesource.com/gvisor/pkg/abi"
+	"gvisor.googlesource.com/gvisor/pkg/eventchannel"
+	"gvisor.googlesource.com/gvisor/pkg/log"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
+	rpb "gvisor.googlesource.com/gvisor/pkg/sentry/arch/registers_go_proto"
+	ucspb "gvisor.googlesource.com/gvisor/pkg/sentry/kernel/uncaught_signal_go_proto"
+	"gvisor.googlesource.com/gvisor/pkg/sentry/strace"
+	spb "gvisor.googlesource.com/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 := strace.Lookup(abi.Linux, arch.AMD64)
+	if !ok {
+		return nil, fmt.Errorf("amd64 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.GetArch().(*rpb.Registers_Amd64).Amd64
+
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	sysnr := regs.OrigRax
+	tr := c.trackers[sysnr]
+	if tr == nil {
+		switch sysnr {
+		case syscall.SYS_PRCTL, syscall.SYS_ARCH_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 = &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.AMD64Registers) bool
+
+	// onReported marks the syscall as reported.
+	onReported(regs *rpb.AMD64Registers)
+}
+
+// onceTracker reports only a single time, used for most syscalls.
+type onceTracker struct {
+	reported bool
+}
+
+func (o *onceTracker) shouldReport(_ *rpb.AMD64Registers) bool {
+	return !o.reported
+}
+
+func (o *onceTracker) onReported(_ *rpb.AMD64Registers) {
+	o.reported = true
+}