mirror of
https://github.com/netbirdio/gvisor.git
synced 2026-05-22 17:12:49 -07:00
Fabricio Voznika
2a0dff228a
`runsc boot` is not guaranteed to file system access to create files. Create save files before the sandbox is created and pass FDs to it, like it's done for other files. PiperOrigin-RevId: 641979089
122 lines
3.4 KiB
Go
122 lines
3.4 KiB
Go
// Copyright 2018 The gVisor Authors.
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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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"strings"
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specs "github.com/opencontainers/runtime-spec/specs-go"
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"golang.org/x/sys/unix"
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"gvisor.dev/gvisor/pkg/fd"
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"gvisor.dev/gvisor/pkg/log"
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"gvisor.dev/gvisor/runsc/specutils"
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)
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// intFlags can be used with int flags that appear multiple times. It supports
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// comma-separated lists too.
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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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sInts := make([]string, 0, len(*i))
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for _, fd := range *i {
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sInts = append(sInts, strconv.Itoa(fd))
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}
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return strings.Join(sInts, ",")
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}
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// Get implements flag.Value.
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func (i *intFlags) Get() any {
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return i
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}
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// GetArray returns an array of ints representing FDs.
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func (i *intFlags) GetArray() []int {
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return *i
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}
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// GetFDs returns an array of *fd.FD.
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func (i *intFlags) GetFDs() []*fd.FD {
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rv := make([]*fd.FD, 0, len(*i))
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for _, val := range *i {
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rv = append(rv, fd.New(val))
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}
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return rv
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}
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// Set implements flag.Value. Set(String()) should be idempotent.
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func (i *intFlags) Set(s string) error {
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for _, sFD := range strings.Split(s, ",") {
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fd, err := strconv.Atoi(sFD)
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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 < -1 {
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return fmt.Errorf("flag value must be >= -1: %d", fd)
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}
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*i = append(*i, fd)
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}
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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 := unix.Exec(binPath, args, os.Environ())
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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 := unix.RawSyscall(unix.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 := unix.RawSyscall(unix.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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// Drop all capabilities.
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if err := applyCaps(&specs.LinuxCapabilities{}); err != nil {
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return fmt.Errorf("error dropping capabilities: %w", 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 := unix.Exec(binPath, args, os.Environ())
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return fmt.Errorf("error executing %s: %v", binPath, err)
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}
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