36 lines
977 B
Go
36 lines
977 B
Go
// Package safeio reads installation files without following symlinked path components.
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package safeio
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import (
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"errors"
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"io"
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"os"
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"path/filepath"
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"strings"
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)
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var ErrUnsafeFile = errors.New("unsafe file")
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// ValidateCanonicalPath rejects relative or lexically non-canonical paths before they are opened.
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func ValidateCanonicalPath(path string) error {
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if !filepath.IsAbs(path) || filepath.Clean(path) != path || strings.Contains(path, string(filepath.Separator)+".."+string(filepath.Separator)) {
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return ErrUnsafeFile
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}
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return nil
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}
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func readBoundedRegularFile(file *os.File, maximum int64) ([]byte, error) {
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if maximum < 0 || maximum == int64(^uint64(0)>>1) {
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return nil, ErrUnsafeFile
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}
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info, err := file.Stat()
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if err != nil || !info.Mode().IsRegular() {
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return nil, ErrUnsafeFile
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}
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contents, err := io.ReadAll(io.LimitReader(file, maximum+1))
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if err != nil || int64(len(contents)) > maximum {
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return nil, ErrUnsafeFile
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}
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return contents, nil
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}
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