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If a blob in a pack file can be decrypted successfully but contains data that results in a different hash than stated in the header pack, then abort repacking. As both the pack header and the blob are cryptographically verified this either means than a malicious entity tampered with the backup or indicates hardware problems on the client. prune should fail with an error in both cases.
119 lines
3.1 KiB
Go
119 lines
3.1 KiB
Go
package repository
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import (
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"context"
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"github.com/restic/restic/internal/debug"
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"github.com/restic/restic/internal/errors"
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"github.com/restic/restic/internal/fs"
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"github.com/restic/restic/internal/pack"
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"github.com/restic/restic/internal/restic"
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)
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// Repack takes a list of packs together with a list of blobs contained in
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// these packs. Each pack is loaded and the blobs listed in keepBlobs is saved
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// into a new pack. Returned is the list of obsolete packs which can then
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// be removed.
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func Repack(ctx context.Context, repo restic.Repository, packs restic.IDSet, keepBlobs restic.BlobSet, p *restic.Progress) (obsoletePacks restic.IDSet, err error) {
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if p != nil {
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p.Start()
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defer p.Done()
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}
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debug.Log("repacking %d packs while keeping %d blobs", len(packs), len(keepBlobs))
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for packID := range packs {
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// load the complete pack into a temp file
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h := restic.Handle{Type: restic.PackFile, Name: packID.String()}
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tempfile, hash, packLength, err := DownloadAndHash(ctx, repo.Backend(), h)
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if err != nil {
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return nil, errors.Wrap(err, "Repack")
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}
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debug.Log("pack %v loaded (%d bytes), hash %v", packID, packLength, hash)
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if !packID.Equal(hash) {
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return nil, errors.Errorf("hash does not match id: want %v, got %v", packID, hash)
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}
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_, err = tempfile.Seek(0, 0)
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if err != nil {
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return nil, errors.Wrap(err, "Seek")
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}
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blobs, err := pack.List(repo.Key(), tempfile, packLength)
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if err != nil {
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return nil, err
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}
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debug.Log("processing pack %v, blobs: %v", packID, len(blobs))
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var buf []byte
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for _, entry := range blobs {
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h := restic.BlobHandle{ID: entry.ID, Type: entry.Type}
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if !keepBlobs.Has(h) {
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continue
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}
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debug.Log(" process blob %v", h)
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buf = buf[:]
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if uint(len(buf)) < entry.Length {
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buf = make([]byte, entry.Length)
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}
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buf = buf[:entry.Length]
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n, err := tempfile.ReadAt(buf, int64(entry.Offset))
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if err != nil {
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return nil, errors.Wrap(err, "ReadAt")
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}
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if n != len(buf) {
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return nil, errors.Errorf("read blob %v from %v: not enough bytes read, want %v, got %v",
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h, tempfile.Name(), len(buf), n)
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}
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nonce, ciphertext := buf[:repo.Key().NonceSize()], buf[repo.Key().NonceSize():]
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plaintext, err := repo.Key().Open(ciphertext[:0], nonce, ciphertext, nil)
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if err != nil {
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return nil, err
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}
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id := restic.Hash(plaintext)
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if !id.Equal(entry.ID) {
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debug.Log("read blob %v/%v from %v: wrong data returned, hash is %v",
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h.Type, h.ID, tempfile.Name(), id)
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return nil, errors.Errorf("read blob %v from %v: wrong data returned, hash is %v",
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h, tempfile.Name(), id)
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}
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// We do want to save already saved blobs!
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_, _, err = repo.SaveBlob(ctx, entry.Type, plaintext, entry.ID, true)
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if err != nil {
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return nil, err
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}
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debug.Log(" saved blob %v", entry.ID)
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keepBlobs.Delete(h)
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}
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if err = tempfile.Close(); err != nil {
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return nil, errors.Wrap(err, "Close")
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}
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if err = fs.RemoveIfExists(tempfile.Name()); err != nil {
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return nil, errors.Wrap(err, "Remove")
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}
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if p != nil {
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p.Report(restic.Stat{Blobs: 1})
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}
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}
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if err := repo.Flush(ctx); err != nil {
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return nil, err
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}
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return packs, nil
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}
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