1 files changed, 66 insertions, 6 deletions

diff --git a/runsc/boot/compat.go b/runsc/boot/compat.go
index 6766953b3..d18c2f802 100644
--- a/runsc/boot/compat.go
+++ b/runsc/boot/compat.go
@@ -17,6 +17,8 @@ package boot
 import (
 	"fmt"
 	"os"
+	"sync"
+	"syscall"
 
 	"github.com/golang/protobuf/proto"
 	"gvisor.googlesource.com/gvisor/pkg/abi"
@@ -25,7 +27,7 @@ import (
 	"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
 	rpb "gvisor.googlesource.com/gvisor/pkg/sentry/arch/registers_go_proto"
 	"gvisor.googlesource.com/gvisor/pkg/sentry/strace"
-	spb "gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/unimplemented_syscall_go_proto"
+	spb "gvisor.googlesource.com/gvisor/pkg/sentry/unimpl/unimplemented_syscall_go_proto"
 )
 
 func initCompatLogs(fd int) error {
@@ -40,15 +42,27 @@ func initCompatLogs(fd int) error {
 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) {
-	// Always logs to default logger.
 	nameMap, ok := strace.Lookup(abi.Linux, arch.AMD64)
 	if !ok {
 		return nil, fmt.Errorf("amd64 Linux syscall table not found")
 	}
-	c := &compatEmitter{sink: log.Log(), nameMap: nameMap}
+
+	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")
@@ -61,10 +75,33 @@ func newCompatEmitter(logFD int) (*compatEmitter, error) {
 // Emit implements eventchannel.Emitter.
 func (c *compatEmitter) Emit(msg proto.Message) (hangup bool, err error) {
 	// Only interested in UnimplementedSyscall, skip the rest.
-	if us, ok := msg.(*spb.UnimplementedSyscall); ok {
-		regs := us.Registers.GetArch().(*rpb.Registers_Amd64).Amd64
-		sysnr := regs.OrigRax
+	us, ok := msg.(*spb.UnimplementedSyscall)
+	if !ok {
+		return false, nil
+	}
+	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:
+			tr = newCmdTracker(0)
+
+		case syscall.SYS_IOCTL, syscall.SYS_EPOLL_CTL, syscall.SYS_SHMCTL:
+			tr = newCmdTracker(1)
+
+		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)
 	}
 	return false, nil
 }
@@ -74,3 +111,26 @@ 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
+}