1 files changed, 117 insertions, 0 deletions
diff --git a/runsc/cmd/cmd.go b/runsc/cmd/cmd.go
new file mode 100644
index 000000000..a2fc377d1
--- /dev/null
+++ b/runsc/cmd/cmd.go
@@ -0,0 +1,117 @@
+// 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 cmd holds implementations of the runsc commands.
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"strconv"
+	"syscall"
+
+	"github.com/google/subcommands"
+	specs "github.com/opencontainers/runtime-spec/specs-go"
+	"gvisor.googlesource.com/gvisor/pkg/log"
+	"gvisor.googlesource.com/gvisor/runsc/specutils"
+)
+
+// Errorf logs to stderr and returns subcommands.ExitFailure.
+func Errorf(s string, args ...interface{}) subcommands.ExitStatus {
+	// If runsc is being invoked by docker or cri-o, then we might not have
+	// access to stderr, so we log a serious-looking warning in addition to
+	// writing to stderr.
+	log.Warningf("FATAL ERROR: "+s, args...)
+	fmt.Fprintf(os.Stderr, s+"\n", args...)
+	// Return an error that is unlikely to be used by the application.
+	return subcommands.ExitFailure
+}
+
+// Fatalf logs to stderr and exits with a failure status code.
+func Fatalf(s string, args ...interface{}) {
+	Errorf(s, args...)
+	os.Exit(128)
+}
+
+// intFlags can be used with int flags that appear multiple times.
+type intFlags []int
+
+// String implements flag.Value.
+func (i *intFlags) String() string {
+	return fmt.Sprintf("%v", *i)
+}
+
+// Get implements flag.Value.
+func (i *intFlags) Get() interface{} {
+	return i
+}
+
+// GetArray returns array of FDs.
+func (i *intFlags) GetArray() []int {
+	return *i
+}
+
+// Set implements flag.Value.
+func (i *intFlags) Set(s string) error {
+	fd, err := strconv.Atoi(s)
+	if err != nil {
+		return fmt.Errorf("invalid flag value: %v", err)
+	}
+	if fd < 0 {
+		return fmt.Errorf("flag value must be greater than 0: %d", fd)
+	}
+	*i = append(*i, fd)
+	return nil
+}
+
+// setCapsAndCallSelf sets capabilities to the current thread and then execve's
+// itself again with the arguments specified in 'args' to restart the process
+// with the desired capabilities.
+func setCapsAndCallSelf(args []string, caps *specs.LinuxCapabilities) error {
+	// Keep thread locked while capabilities are changed.
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	if err := applyCaps(caps); err != nil {
+		return fmt.Errorf("applyCaps() failed: %v", err)
+	}
+	binPath := specutils.ExePath
+
+	log.Infof("Execve %q again, bye!", binPath)
+	err := syscall.Exec(binPath, args, []string{})
+	return fmt.Errorf("error executing %s: %v", binPath, err)
+}
+
+// callSelfAsNobody sets UID and GID to nobody and then execve's itself again.
+func callSelfAsNobody(args []string) error {
+	// Keep thread locked while user/group are changed.
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	const nobody = 65534
+
+	if _, _, err := syscall.RawSyscall(syscall.SYS_SETGID, uintptr(nobody), 0, 0); err != 0 {
+		return fmt.Errorf("error setting uid: %v", err)
+	}
+	if _, _, err := syscall.RawSyscall(syscall.SYS_SETUID, uintptr(nobody), 0, 0); err != 0 {
+		return fmt.Errorf("error setting gid: %v", err)
+	}
+
+	binPath := specutils.ExePath
+
+	log.Infof("Execve %q again, bye!", binPath)
+	err := syscall.Exec(binPath, args, []string{})
+	return fmt.Errorf("error executing %s: %v", binPath, err)
+}