58 lines
1.7 KiB
Go
58 lines
1.7 KiB
Go
//go:build !windows
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package safeio
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import (
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"os"
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"strings"
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"golang.org/x/sys/unix"
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)
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// ReadCanonicalRegular opens an absolute canonical path component by component from the root
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// descriptor. O_NOFOLLOW rejects symlinks at every component, and the open directory descriptors
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// prevent later parent replacement from redirecting the final open.
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func ReadCanonicalRegular(path string, maximum int64) ([]byte, error) {
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if err := ValidateCanonicalPath(path); err != nil {
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return nil, err
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}
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components := strings.Split(strings.TrimPrefix(path, string(os.PathSeparator)), string(os.PathSeparator))
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if len(components) == 0 || components[0] == "" {
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return nil, ErrUnsafeFile
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}
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directory, err := unix.Open(string(os.PathSeparator), unix.O_RDONLY|unix.O_CLOEXEC|unix.O_DIRECTORY, 0)
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if err != nil {
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return nil, ErrUnsafeFile
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}
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directories := []int{directory}
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defer func() { closeUnixDescriptors(directories) }()
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for _, component := range components[:len(components)-1] {
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nextDirectory, err := unix.Openat(directory, component, unix.O_RDONLY|unix.O_CLOEXEC|unix.O_DIRECTORY|unix.O_NOFOLLOW, 0)
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if err != nil {
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return nil, ErrUnsafeFile
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}
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directory = nextDirectory
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directories = append(directories, directory)
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}
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descriptor, err := unix.Openat(directory, components[len(components)-1], unix.O_RDONLY|unix.O_CLOEXEC|unix.O_NOFOLLOW|unix.O_NONBLOCK, 0)
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if err != nil {
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return nil, ErrUnsafeFile
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}
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file := os.NewFile(uintptr(descriptor), "thothctl-safeio")
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if file == nil {
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unix.Close(descriptor)
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return nil, ErrUnsafeFile
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}
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defer file.Close()
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return readBoundedRegularFile(path, file, maximum)
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}
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func closeUnixDescriptors(descriptors []int) {
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for _, descriptor := range descriptors {
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unix.Close(descriptor)
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}
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}
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