85 lines
2.3 KiB
Go
85 lines
2.3 KiB
Go
package fusefrontend
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import (
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"path/filepath"
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"strings"
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"syscall"
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"github.com/rfjakob/gocryptfs/internal/nametransform"
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"github.com/rfjakob/gocryptfs/internal/syscallcompat"
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)
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// openBackingDir opens the parent ciphertext directory of plaintext path
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// "relPath". It returns the dirfd (opened with O_PATH) and the encrypted
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// basename.
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//
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// The caller should then use Openat(dirfd, cName, ...) and friends.
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// For convenience, if relPath is "", cName is going to be ".".
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//
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// openBackingDir is secure against symlink races by using Openat and
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// ReadDirIVAt.
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func (fs *FS) openBackingDir(relPath string) (dirfd int, cName string, err error) {
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dirRelPath := nametransform.Dir(relPath)
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// With PlaintextNames, we don't need to read DirIVs. Easy.
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if fs.args.PlaintextNames {
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dirfd, err = syscallcompat.OpenDirNofollow(fs.args.Cipherdir, dirRelPath)
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if err != nil {
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return -1, "", err
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}
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// If relPath is empty, cName is ".".
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cName = filepath.Base(relPath)
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return dirfd, cName, nil
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}
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// Cache lookup
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dirfd, iv := fs.dirCache.Lookup(dirRelPath)
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if dirfd > 0 {
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// If relPath is empty, cName is ".".
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if relPath == "" {
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return dirfd, ".", nil
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}
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name := filepath.Base(relPath)
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cName, err = fs.nameTransform.EncryptAndHashName(name, iv)
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if err != nil {
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syscall.Close(dirfd)
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return -1, "", err
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}
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return dirfd, cName, nil
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}
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// Open cipherdir (following symlinks)
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dirfd, err = syscall.Open(fs.args.Cipherdir, syscall.O_DIRECTORY|syscallcompat.O_PATH, 0)
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if err != nil {
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return -1, "", err
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}
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// If relPath is empty, cName is ".".
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if relPath == "" {
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return dirfd, ".", nil
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}
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// Walk the directory tree
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parts := strings.Split(relPath, "/")
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for i, name := range parts {
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iv, err := nametransform.ReadDirIVAt(dirfd)
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if err != nil {
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syscall.Close(dirfd)
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return -1, "", err
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}
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cName, err = fs.nameTransform.EncryptAndHashName(name, iv)
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if err != nil {
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syscall.Close(dirfd)
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return -1, "", err
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}
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// Last part? We are done.
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if i == len(parts)-1 {
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fs.dirCache.Store(dirRelPath, dirfd, iv)
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break
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}
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// Not the last part? Descend into next directory.
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dirfd2, err := syscallcompat.Openat(dirfd, cName, syscall.O_NOFOLLOW|syscall.O_DIRECTORY|syscallcompat.O_PATH, 0)
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syscall.Close(dirfd)
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if err != nil {
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return -1, "", err
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}
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dirfd = dirfd2
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}
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return dirfd, cName, nil
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}
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