48 lines
1.5 KiB
Go
48 lines
1.5 KiB
Go
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package nametransform
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import (
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"fmt"
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"strings"
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"syscall"
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"github.com/rfjakob/gocryptfs/v2/internal/tlog"
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)
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// xattr names are encrypted like file names, but with a fixed IV.
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// Padded with "_xx" for length 16.
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var xattrNameIV = []byte("xattr_name_iv_xx")
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func isValidXattrName(name string) error {
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if name == "" {
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return fmt.Errorf("empty input")
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}
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if strings.Contains(name, "\000") {
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return fmt.Errorf("contains forbidden null byte")
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}
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return nil
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}
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// EncryptXattrName encrypts an extended attribute (xattr) name.
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// xattr names are encrypted like file names, but with a fixed IV, and fewer
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// naming restriction.
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func (n *NameTransform) EncryptXattrName(plainName string) (cipherName64 string, err error) {
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if err := isValidXattrName(plainName); err != nil {
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tlog.Warn.Printf("EncryptXattrName %q: invalid plainName: %v", plainName, err)
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return "", syscall.EBADMSG
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}
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return n.encryptName(plainName, xattrNameIV), nil
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}
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// DecryptName calls decryptName to try and decrypt a base64-encoded encrypted
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// filename "cipherName", and failing that checks if it can be bypassed
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func (n *NameTransform) DecryptXattrName(cipherName string) (plainName string, err error) {
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if plainName, err = n.decryptName(cipherName, xattrNameIV); err != nil {
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return "", err
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}
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if err := isValidXattrName(plainName); err != nil {
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tlog.Warn.Printf("DecryptXattrName %q: invalid name after decryption: %v", cipherName, err)
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return "", syscall.EBADMSG
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}
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return plainName, err
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}
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