111 lines
3.3 KiB
Go
111 lines
3.3 KiB
Go
// Copyright 2018 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package cmd holds implementations of the runsc commands.
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package cmd
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import (
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"fmt"
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"os"
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"runtime"
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"strconv"
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"syscall"
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specs "github.com/opencontainers/runtime-spec/specs-go"
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"gvisor.googlesource.com/gvisor/pkg/log"
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"gvisor.googlesource.com/gvisor/runsc/specutils"
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)
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// Fatalf logs to stderr and exits with a failure status code.
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func Fatalf(s string, args ...interface{}) {
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// If runsc is being invoked by docker or cri-o, then we might not have
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// access to stderr, so we log a serious-looking warning in addition to
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// writing to stderr.
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log.Warningf("FATAL ERROR: "+s, args...)
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fmt.Fprintf(os.Stderr, s+"\n", args...)
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// Return an error that is unlikely to be used by the application.
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os.Exit(128)
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}
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// intFlags can be used with int flags that appear multiple times.
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type intFlags []int
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// String implements flag.Value.
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func (i *intFlags) String() string {
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return fmt.Sprintf("%v", *i)
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}
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// Get implements flag.Value.
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func (i *intFlags) Get() interface{} {
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return i
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}
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// GetArray returns array of FDs.
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func (i *intFlags) GetArray() []int {
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return *i
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}
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// Set implements flag.Value.
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func (i *intFlags) Set(s string) error {
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fd, err := strconv.Atoi(s)
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if err != nil {
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return fmt.Errorf("invalid flag value: %v", err)
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}
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if fd < 0 {
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return fmt.Errorf("flag value must be greater than 0: %d", fd)
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}
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*i = append(*i, fd)
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return nil
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}
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// setCapsAndCallSelf sets capabilities to the current thread and then execve's
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// itself again with the arguments specified in 'args' to restart the process
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// with the desired capabilities.
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func setCapsAndCallSelf(args []string, caps *specs.LinuxCapabilities) error {
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// Keep thread locked while capabilities are changed.
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runtime.LockOSThread()
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defer runtime.UnlockOSThread()
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if err := applyCaps(caps); err != nil {
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return fmt.Errorf("applyCaps() failed: %v", err)
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}
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binPath := specutils.ExePath
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log.Infof("Execve %q again, bye!", binPath)
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err := syscall.Exec(binPath, args, []string{})
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return fmt.Errorf("error executing %s: %v", binPath, err)
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}
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// callSelfAsNobody sets UID and GID to nobody and then execve's itself again.
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func callSelfAsNobody(args []string) error {
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// Keep thread locked while user/group are changed.
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runtime.LockOSThread()
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defer runtime.UnlockOSThread()
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const nobody = 65534
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if _, _, err := syscall.RawSyscall(syscall.SYS_SETGID, uintptr(nobody), 0, 0); err != 0 {
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return fmt.Errorf("error setting uid: %v", err)
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}
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if _, _, err := syscall.RawSyscall(syscall.SYS_SETUID, uintptr(nobody), 0, 0); err != 0 {
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return fmt.Errorf("error setting gid: %v", err)
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}
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binPath := specutils.ExePath
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log.Infof("Execve %q again, bye!", binPath)
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err := syscall.Exec(binPath, args, []string{})
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return fmt.Errorf("error executing %s: %v", binPath, err)
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}
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