mirror of
https://github.com/clearlinux/rkt.git
synced 2026-08-29 22:53:48 +00:00
Simone Gotti
2c66843cc1
this introduces tar extraction inside a chroot. This is done spawning a new process. Instead of creating a new executable (difficult to find, package etc...) it adds the concept of a multicall process (like busybox). Now a new multicall command "extracttar" is added. tar.ExtractTar executes this new command passing a pipe to send the filesMap and the tar contents to stdin. The incomplete "insecure link" checks are removed from the the tar functions. Additionally these functions are now not exported and the extraction directory is always the root directory.
88 lines
2.3 KiB
Go
88 lines
2.3 KiB
Go
// Copyright 2015 The rkt 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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// inspired by github.com/docker/docker/pkg/reexec
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//+build linux
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package multicall
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import (
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"fmt"
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"os"
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"os/exec"
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"syscall"
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)
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var exePath string
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func init() {
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// save the program path
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var err error
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exePath, err = os.Readlink("/proc/self/exe")
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if err != nil {
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panic("cannot get current executable")
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}
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}
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type commandFn func() error
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var commands = make(map[string]commandFn)
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// Entrypoint provides the access to a multicall command.
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type Entrypoint string
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// Add adds a new multicall command. name is the command name and fn is the
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// function that will be executed for the specified command. It returns the
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// related Entrypoint.
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// Packages adding new multicall commands should call Add in their init
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// function.
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func Add(name string, fn commandFn) Entrypoint {
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if _, ok := commands[name]; ok {
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panic(fmt.Errorf("command with name %q already exists", name))
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}
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commands[name] = fn
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return Entrypoint(name)
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}
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// MaybeExec should be called at the start of the program, if the process argv[0] is
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// a name registered with multicall, the related function will be executed.
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// If the functions returns an error, it will be printed to stderr and will
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// exit with an exit status of 1, otherwise it will exit with a 0 exit
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// status.
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func MaybeExec() {
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name := os.Args[0]
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if fn, ok := commands[name]; ok {
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if err := fn(); err != nil {
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fmt.Fprintln(os.Stderr, err)
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os.Exit(1)
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}
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os.Exit(0)
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}
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}
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// Cmd will prepare the *exec.Cmd for the given entrypoint, configured with the
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// provided args.
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func (e Entrypoint) Cmd(args ...string) *exec.Cmd {
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// append the Entrypoint as argv[0]
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args = append([]string{string(e)}, args...)
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return &exec.Cmd{
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Path: exePath,
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Args: args,
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SysProcAttr: &syscall.SysProcAttr{
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Pdeathsig: syscall.SIGTERM,
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},
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}
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}
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