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backups: do not hardcode limit values in the code (#771)

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Also introduce limit for stderr read from VM (anti DoS protection).
This commit is contained in:
Marek Marczykowski-Górecki 2014-01-15 03:35:12 +01:00
parent b85cd0448f
commit a2037a4985
1 changed files with 8 additions and 3 deletions
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11
core/backup.py
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@ -39,6 +39,11 @@ from multiprocessing import Queue,Process
BACKUP_DEBUG = False BACKUP_DEBUG = False
# Maximum size of error message get from process stderr (including VM process)
MAX_STDERR_BYTES = 1024
# header + qubes.xml max size
HEADER_QUBES_XML_MAX_SIZE = 1024 * 1024
def get_disk_usage(file_or_dir): def get_disk_usage(file_or_dir):
if not os.path.exists(file_or_dir): if not os.path.exists(file_or_dir):
return 0 return 0
@ -492,7 +497,7 @@ def backup_do(base_backup_dir, files_to_backup, passphrase,
send_proc.terminate() send_proc.terminate()
if run_error == "VM" and vmproc: if run_error == "VM" and vmproc:
raise QubesException("Failed to write the backup, VM output:\n" + raise QubesException("Failed to write the backup, VM output:\n" +
vmproc.stderr.read()) vmproc.stderr.read(MAX_STDERR_BYTES))
else: else:
raise QubesException("Failed to perform backup: error in "+ \ raise QubesException("Failed to perform backup: error in "+ \
run_error) run_error)
@ -930,7 +935,7 @@ def restore_vm_dirs (backup_source, restore_tmpdir, passphrase, vms_dirs, vms,
raise QubesException( raise QubesException(
"ERROR: unable to read the qubes backup {0} " \ "ERROR: unable to read the qubes backup {0} " \
"because of a VM error: {1}".format( "because of a VM error: {1}".format(
backup_source, vmproc.stderr.read())) backup_source, vmproc.stderr.read(MAX_STDERR_BYTES)))
if filename and filename!="EOF": if filename and filename!="EOF":
raise QubesException("Premature end of archive, the last file was %s" % filename) raise QubesException("Premature end of archive, the last file was %s" % filename)
@ -1007,7 +1012,7 @@ def backup_restore_header(source, passphrase,
passphrase=passphrase, passphrase=passphrase,
vms_dirs=extract_filter, vms_dirs=extract_filter,
vms=None, vms=None,
vms_size=40000, vms_size=HEADER_QUBES_XML_MAX_SIZE,
print_callback=print_callback, print_callback=print_callback,
error_callback=error_callback, error_callback=error_callback,
progress_callback=None, progress_callback=None,