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backup: add 'backup_id' to integrity protection

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This prevent switching parts of backup of the same VM between different
backups made by the same user (or actually: with the same passphrase).

QubesOS/qubes-issues#971
This commit is contained in:
Marek Marczykowski-Górecki 2016-10-25 21:28:59 +02:00
parent 418d749680
commit 4ad15c082b
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GPG Key ID: 063938BA42CFA724
1 changed files with 25 additions and 4 deletions
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29
qubes/backup.py
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@ -80,6 +80,7 @@ class BackupHeader(object):
'compression-filter': 'compression_filter', 'compression-filter': 'compression_filter',
'crypto-algorithm': 'crypto_algorithm', 'crypto-algorithm': 'crypto_algorithm',
'hmac-algorithm': 'hmac_algorithm', 'hmac-algorithm': 'hmac_algorithm',
'backup-id': 'backup_id'
} }
bool_options = ['encrypted', 'compressed'] bool_options = ['encrypted', 'compressed']
int_options = ['version'] int_options = ['version']
@ -91,7 +92,8 @@ class BackupHeader(object):
compressed=None, compressed=None,
compression_filter=None, compression_filter=None,
hmac_algorithm=None, hmac_algorithm=None,
crypto_algorithm=None): crypto_algorithm=None,
backup_id=None):
# repeat the list to help code completion... # repeat the list to help code completion...
self.version = version self.version = version
self.encrypted = encrypted self.encrypted = encrypted
@ -101,6 +103,7 @@ class BackupHeader(object):
self.compression_filter = compression_filter self.compression_filter = compression_filter
self.hmac_algorithm = hmac_algorithm self.hmac_algorithm = hmac_algorithm
self.crypto_algorithm = crypto_algorithm self.crypto_algorithm = crypto_algorithm
self.backup_id = backup_id
if header_data is not None: if header_data is not None:
self.load(header_data) self.load(header_data)
@ -152,6 +155,8 @@ class BackupHeader(object):
expected_attrs += ['crypto_algorithm'] expected_attrs += ['crypto_algorithm']
if self.version >= 3 and self.compressed: if self.version >= 3 and self.compressed:
expected_attrs += ['compression_filter'] expected_attrs += ['compression_filter']
if self.version >= 4:
expected_attrs += ['backup_id']
for key in expected_attrs: for key in expected_attrs:
if getattr(self, key) is None: if getattr(self, key) is None:
raise qubes.exc.QubesException( raise qubes.exc.QubesException(
@ -353,6 +358,10 @@ class Backup(object):
#: callback for progress reporting. Will be called with one argument #: callback for progress reporting. Will be called with one argument
#: - progress in percents #: - progress in percents
self.progress_callback = None self.progress_callback = None
#: backup ID, needs to be unique (for a given user),
#: not necessary unpredictable; automatically generated
self.backup_id = datetime.datetime.now().strftime(
'%Y%m%dT%H%M%S-' + str(os.getpid()))
for key, value in kwargs.iteritems(): for key, value in kwargs.iteritems():
if hasattr(self, key): if hasattr(self, key):
@ -535,6 +544,7 @@ class Backup(object):
encrypted=self.encrypted, encrypted=self.encrypted,
compressed=self.compressed, compressed=self.compressed,
compression_filter=self.compression_filter, compression_filter=self.compression_filter,
backup_id=self.backup_id,
) )
backup_header.save(header_file_path) backup_header.save(header_file_path)
# Start encrypt, scrypt will also handle integrity # Start encrypt, scrypt will also handle integrity
@ -722,8 +732,12 @@ class Backup(object):
# Start encrypt, scrypt will also handle integrity # Start encrypt, scrypt will also handle integrity
# protection # protection
scrypt_passphrase = os.path.relpath(chunkfile[:-4], scrypt_passphrase = \
self.tmpdir) + '!' + passphrase '{backup_id}!{filename}!{passphrase}'.format(
backup_id=self.backup_id,
filename=os.path.relpath(chunkfile[:-4],
self.tmpdir),
passphrase=passphrase)
scrypt = launch_scrypt( scrypt = launch_scrypt(
"enc", "-", chunkfile, scrypt_passphrase) "enc", "-", chunkfile, scrypt_passphrase)
@ -1622,7 +1636,14 @@ class BackupRestore(object):
fulloutput = os.path.join(self.tmpdir, output) fulloutput = os.path.join(self.tmpdir, output)
else: else:
fulloutput = os.path.join(self.tmpdir, origname) fulloutput = os.path.join(self.tmpdir, origname)
passphrase = origname + '!' + self.passphrase.encode('utf-8') if origname == HEADER_FILENAME:
passphrase = origname + '!' + self.passphrase.encode('utf-8')
else:
passphrase = \
'{backup_id}!{filename}!{passphrase}'.format(
backup_id=self.header_data.backup_id,
filename=origname,
passphrase=self.passphrase.encode('utf-8'))
p = launch_scrypt('dec', fullname, fulloutput, passphrase) p = launch_scrypt('dec', fullname, fulloutput, passphrase)
(_, stderr) = p.communicate() (_, stderr) = p.communicate()
if p.returncode != 0: if p.returncode != 0: