72 lines
1.9 KiB
Go
72 lines
1.9 KiB
Go
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package fakeroot
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import (
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"errors"
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"os"
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"os/exec"
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"slices"
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"syscall"
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)
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var (
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// ErrRootUIDAlreadyMapped is returned when there's already a mapping for the root user in a command
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ErrRootUIDAlreadyMapped = errors.New("fakeroot: root user has already been mapped in this command")
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// ErrRootGIDAlreadyMapped is returned when there's already a mapping for the root group in a command
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ErrRootGIDAlreadyMapped = errors.New("fakeroot: root group has already been mapped in this command")
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)
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// Command returns a command that runs in a fakeroot environment
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func Command(name string, arg ...string) (*exec.Cmd, error) {
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cmd := exec.Command(name, arg...)
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return cmd, Apply(cmd)
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}
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// Apply applies the options required to run in a fakeroot environment to
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// a command. It returns an error if the root group or user already has a mapping
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// registered in the command.
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func Apply(cmd *exec.Cmd) error {
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uid := os.Getuid()
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// If the user is already root, there's no need for fakeroot
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if uid == 0 {
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return nil
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}
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// Ensure SysProcAttr isn't nil
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if cmd.SysProcAttr == nil {
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cmd.SysProcAttr = &syscall.SysProcAttr{}
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}
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// Create a new user namespace
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cmd.SysProcAttr.Cloneflags |= syscall.CLONE_NEWUSER
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// If the command already contains a mapping for the root user, return an error
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if slices.ContainsFunc(cmd.SysProcAttr.UidMappings, rootMap) {
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return ErrRootUIDAlreadyMapped
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}
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// If the command already contains a mapping for the root group, return an error
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if slices.ContainsFunc(cmd.SysProcAttr.GidMappings, rootMap) {
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return ErrRootGIDAlreadyMapped
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}
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cmd.SysProcAttr.UidMappings = append(cmd.SysProcAttr.UidMappings, syscall.SysProcIDMap{
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ContainerID: 0,
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HostID: uid,
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Size: 1,
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})
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cmd.SysProcAttr.GidMappings = append(cmd.SysProcAttr.GidMappings, syscall.SysProcIDMap{
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ContainerID: 0,
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HostID: uid,
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Size: 1,
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})
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return nil
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}
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func rootMap(m syscall.SysProcIDMap) bool {
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return m.ContainerID == 0
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}
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