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/usr/share/doc/rsync/support

Name	Size	Mode	Actions
atomic-rsync	5190	0644	edit dl rm
cvs2includes	1216	0644	edit dl rm
deny-rsync	1005	0644	edit dl rm
file-attr-restore	4936	0644	edit dl rm
files-to-excludes	538	0644	edit dl rm
git-set-file-times	3902	0644	edit dl rm
instant-rsyncd	2791	0644	edit dl rm
logfilter	1104	0644	edit dl rm
lsh	3102	0644	edit dl rm
lsh.sh	1108	0644	edit dl rm
Makefile	80	0644	edit dl rm
mapfrom	633	0644	edit dl rm
mapto	625	0644	edit dl rm
mnt-excl	1848	0644	edit dl rm
munge-symlinks	2617	0644	edit dl rm
nameconvert	1527	0644	edit dl rm
rrsync	12617	0644	edit dl rm
rrsync.1.md	4383	0644	edit dl rm
rsync-no-vanished	593	0644	edit dl rm
rsync-slash-strip	769	0644	edit dl rm
rsyncstats	8691	0644	edit dl rm
savetransfer.c	4560	0644	edit dl rm

Edit: /usr/share/doc/rsync/support/rrsync (12617B)

#!/usr/bin/env python3

# Restricts rsync to subdirectory declared in .ssh/authorized_keys.  See
# the rrsync man page for details of how to make use of this script.

# NOTE: install python3 braceexpand to support brace expansion in the args!

# Originally a perl script by: Joe Smith <js-cgi@inwap.com> 30-Sep-2004
# Python version by: Wayne Davison <wayne@opencoder.net>

# You may configure these 2 values to your liking.  See also the section of
# short & long options if you want to disable any options that rsync accepts.
RSYNC = '/usr/bin/rsync'
LOGFILE = 'rrsync.log' # NOTE: the file must exist for a line to be appended!

# The following options are mainly the options that a client rsync can send
# to the server, and usually just in the one option format that the stock
# rsync produces. However, there are some additional convenience options
# added as well, and thus a few options are present in both the short and
# long lists (such as --group, --owner, and --perms).

# NOTE when disabling: check for both a short & long version of the option!

### START of options data produced by the cull-options script. ###

# To disable a short-named option, add its letter to this string:
short_disabled = 's'

# These are also disabled when the restricted dir is not "/":
short_disabled_subdir = 'KLk'

# These are all possible short options that we will accept (when not disabled above):
short_no_arg = 'ACDEHIJKLNORSUWXbcdgklmnopqrstuvxyz' # DO NOT REMOVE ANY
short_with_num = '@B' # DO NOT REMOVE ANY

# To disable a long-named option, change its value to a -1.  The values mean:
# 0 = the option has no arg; 1 = the arg doesn't need any checking; 2 = only
# check the arg when receiving; and 3 = always check the arg.
long_opts = {
  'append': 0,
  'backup-dir': 2,
  'block-size': 1,
  'bwlimit': 1,
  'checksum-choice': 1,
  'checksum-seed': 1,
  'compare-dest': 2,
  'compress-choice': 1,
  'compress-level': 1,
  'copy-dest': 2,
  'copy-unsafe-links': 0,
  'daemon': -1,
  'debug': 1,
  'delay-updates': 0,
  'delete': 0,
  'delete-after': 0,
  'delete-before': 0,
  'delete-delay': 0,
  'delete-during': 0,
  'delete-excluded': 0,
  'delete-missing-args': 0,
  'existing': 0,
  'fake-super': 0,
  'files-from': 3,
  'force': 0,
  'from0': 0,
  'fsync': 0,
  'fuzzy': 0,
  'group': 0,
  'groupmap': 1,
  'hard-links': 0,
  'iconv': 1,
  'ignore-errors': 0,
  'ignore-existing': 0,
  'ignore-missing-args': 0,
  'ignore-times': 0,
  'info': 1,
  'inplace': 0,
  'link-dest': 2,
  'links': 0,
  'list-only': 0,
  'log-file': 3,
  'log-format': 1,
  'max-alloc': 1,
  'max-delete': 1,
  'max-size': 1,
  'min-size': 1,
  'mkpath': 0,
  'modify-window': 1,
  'msgs2stderr': 0,
  'munge-links': 0,
  'new-compress': 0,
  'no-W': 0,
  'no-implied-dirs': 0,
  'no-msgs2stderr': 0,
  'no-munge-links': -1,
  'no-r': 0,
  'no-relative': 0,
  'no-specials': 0,
  'numeric-ids': 0,
  'old-compress': 0,
  'one-file-system': 0,
  'only-write-batch': 1,
  'open-noatime': 0,
  'owner': 0,
  'partial': 0,
  'partial-dir': 2,
  'perms': 0,
  'preallocate': 0,
  'recursive': 0,
  'remove-sent-files': 0,
  'remove-source-files': 0,
  'safe-links': 0,
  'sender': 0,
  'server': 0,
  'size-only': 0,
  'skip-compress': 1,
  'specials': 0,
  'stats': 0,
  'stderr': 1,
  'suffix': 1,
  'super': 0,
  'temp-dir': 2,
  'timeout': 1,
  'times': 0,
  'use-qsort': 0,
  'usermap': 1,
  'write-devices': -1,
}

### END of options data produced by the cull-options script. ###

import os, sys, re, argparse, glob, socket, time, subprocess
from argparse import RawTextHelpFormatter

try:
    from braceexpand import braceexpand
except:
    braceexpand = lambda x: [ DE_BACKSLASH_RE.sub(r'\1', x) ]

HAS_DOT_DOT_RE = re.compile(r'(^|/)\.\.(/|$)')
LONG_OPT_RE = re.compile(r'^--([^=]+)(?:=(.*))?$')
DE_BACKSLASH_RE = re.compile(r'\\(.)')

def main():
    if not os.path.isdir(args.dir):
        die("Restricted directory does not exist!")

# The format of the environment variables set by sshd:
    #   SSH_ORIGINAL_COMMAND:
    #     rsync --server          -vlogDtpre.iLsfxCIvu --etc . ARG  # push
    #     rsync --server --sender -vlogDtpre.iLsfxCIvu --etc . ARGS # pull
    #   SSH_CONNECTION (client_ip client_port server_ip server_port):
    #     192.168.1.100 64106 192.168.1.2 22

command = os.environ.get('SSH_ORIGINAL_COMMAND', None)
    if not command:
        die("Not invoked via sshd")
    command = command.split(' ', 2)
    if command[0:1] != ['rsync']:
        die("SSH_ORIGINAL_COMMAND does not run rsync")
    if command[1:2] != ['--server']:
        die("--server option is not the first arg")
    command = '' if len(command) < 3 else command[2]

global am_sender
    am_sender = command.startswith("--sender ") # Restrictive on purpose!
    if args.ro and not am_sender:
        die("sending to read-only server is not allowed")
    if args.wo and am_sender:
        die("reading from write-only server is not allowed")

if args.wo or not am_sender:
        long_opts['sender'] = -1
    if args.no_del:
        for opt in long_opts:
            if opt.startswith(('remove', 'delete')):
                long_opts[opt] = -1
    if args.ro:
        long_opts['log-file'] = -1

if args.dir != '/':
        global short_disabled
        short_disabled += short_disabled_subdir

short_no_arg_re = short_no_arg
    short_with_num_re = short_with_num
    if short_disabled:
        for ltr in short_disabled:
            short_no_arg_re = short_no_arg_re.replace(ltr, '')
            short_with_num_re = short_with_num_re.replace(ltr, '')
        short_disabled_re = re.compile(r'^-[%s]*([%s])' % (short_no_arg_re, short_disabled))
    short_no_arg_re = re.compile(r'^-(?=.)[%s]*(e\d*\.\w*)?$' % short_no_arg_re)
    short_with_num_re = re.compile(r'^-[%s]\d+$' % short_with_num_re)

log_fh = open(LOGFILE, 'a') if os.path.isfile(LOGFILE) else None

try:
        os.chdir(args.dir)
    except OSError as e:
        die('unable to chdir to restricted dir:', str(e))

rsync_opts = [ '--server' ]
    rsync_args = [ ]
    saw_the_dot_arg = False
    last_opt = check_type = None

for arg in re.findall(r'(?:[^\s\\]+|\\.[^\s\\]*)+', command):
        if check_type:
            rsync_opts.append(validated_arg(last_opt, arg, check_type))
            check_type = None
        elif saw_the_dot_arg:
            # NOTE: an arg that starts with a '-' is safe due to our use of "--" in the cmd tuple.
            try:
                b_e = braceexpand(arg) # Also removes backslashes
            except: # Handle errors such as unbalanced braces by just de-backslashing the arg:
                b_e = [ DE_BACKSLASH_RE.sub(r'\1', arg) ]
            for xarg in b_e:
                rsync_args += validated_arg('arg', xarg, wild=True)
        else: # parsing the option args
            if arg == '.':
                saw_the_dot_arg = True
                continue
            rsync_opts.append(arg)
            if short_no_arg_re.match(arg) or short_with_num_re.match(arg):
                continue
            disabled = False
            m = LONG_OPT_RE.match(arg)
            if m:
                opt = m.group(1)
                opt_arg = m.group(2)
                ct = long_opts.get(opt, None)
                if ct is None:
                    break # Generate generic failure due to unfinished arg parsing
                if ct == 0:
                    continue
                opt = '--' + opt
                if ct > 0:
                    if opt_arg is not None:
                        rsync_opts[-1] = opt + '=' + validated_arg(opt, opt_arg, ct)
                    else:
                        check_type = ct
                        last_opt = opt
                    continue
                disabled = True
            elif short_disabled:
                m = short_disabled_re.match(arg)
                if m:
                    disabled = True
                    opt = '-' + m.group(1)

if disabled:
                die("option", opt, "has been disabled on this server.")
            break # Generate a generic failure

if not saw_the_dot_arg:
        die("invalid rsync-command syntax or options")

if args.munge:
        rsync_opts.append('--munge-links')

if not rsync_args:
        rsync_args = [ '.' ]

cmd = (RSYNC, *rsync_opts, '--', '.', *rsync_args)

if log_fh:
        now = time.localtime()
        host = os.environ.get('SSH_CONNECTION', 'unknown').split()[0] # Drop everything after the IP addr
        if host.startswith('::ffff:'):
            host = host[7:]
        try:
            host = socket.gethostbyaddr(socket.inet_aton(host))
        except:
            pass
        log_fh.write("%02d:%02d:%02d %-16s %s\n" % (now.tm_hour, now.tm_min, now.tm_sec, host, str(cmd)))
        log_fh.close()

# NOTE: This assumes that the rsync protocol will not be maliciously hijacked.
    if args.no_lock:
        os.execlp(RSYNC, *cmd)
        die("execlp(", RSYNC, *cmd, ')  failed')
    child = subprocess.run(cmd)
    if child.returncode != 0:
        sys.exit(child.returncode)

def validated_arg(opt, arg, typ=3, wild=False):
    if opt != 'arg': # arg values already have their backslashes removed.
        arg = DE_BACKSLASH_RE.sub(r'\1', arg)

orig_arg = arg
    if arg.startswith('./'):
        arg = arg[1:]
    arg = arg.replace('//', '/')
    if args.dir != '/':
        if HAS_DOT_DOT_RE.search(arg):
            die("do not use .. in", opt, "(anchor the path at the root of your restricted dir)")
        if arg.startswith('/'):
            arg = args.dir + arg

if wild:
        got = glob.glob(arg)
        if not got:
            got = [ arg ]
    else:
        got = [ arg ]

ret = [ ]
    for arg in got:
        if args.dir != '/' and arg != '.' and (typ == 3 or (typ == 2 and not am_sender)):
            arg_has_trailing_slash = arg.endswith('/')
            if arg_has_trailing_slash:
                arg = arg[:-1]
            else:
                arg_has_trailing_slash_dot = arg.endswith('/.')
                if arg_has_trailing_slash_dot:
                    arg = arg[:-2]
            real_arg = os.path.realpath(arg)
            if arg != real_arg and not real_arg.startswith(args.dir_slash):
                die('unsafe arg:', orig_arg, [arg, real_arg])
            if arg_has_trailing_slash:
                arg += '/'
            elif arg_has_trailing_slash_dot:
                arg += '/.'
            if opt == 'arg' and arg.startswith(args.dir_slash):
                arg = arg[args.dir_slash_len:]
                if arg == '':
                    arg = '.'
        ret.append(arg)

return ret if wild else ret[0]

def lock_or_die(dirname):
    import fcntl
    global lock_handle
    lock_handle = os.open(dirname, os.O_RDONLY)
    try:
        fcntl.flock(lock_handle, fcntl.LOCK_EX | fcntl.LOCK_NB)
    except:
        die('Another instance of rrsync is already accessing this directory.')

def die(*msg):
    print(sys.argv[0], 'error:', *msg, file=sys.stderr)
    if sys.stdin.isatty():
        arg_parser.print_help(sys.stderr)
    sys.exit(1)

# This class displays the --help to the user on argparse error IFF they're running it interactively.
class OurArgParser(argparse.ArgumentParser):
    def error(self, msg):
        die(msg)

if __name__ == '__main__':
    our_desc = """Use "man rrsync" to learn how to restrict ssh users to using a restricted rsync command."""
    arg_parser = OurArgParser(description=our_desc, add_help=False)
    only_group = arg_parser.add_mutually_exclusive_group()
    only_group.add_argument('-ro', action='store_true', help="Allow only reading from the DIR. Implies -no-del and -no-lock.")
    only_group.add_argument('-wo', action='store_true', help="Allow only writing to the DIR.")
    arg_parser.add_argument('-munge', action='store_true', help="Enable rsync's --munge-links on the server side.")
    arg_parser.add_argument('-no-del', action='store_true', help="Disable rsync's --delete* and --remove* options.")
    arg_parser.add_argument('-no-lock', action='store_true', help="Avoid the single-run (per-user) lock check.")
    arg_parser.add_argument('-help', '-h', action='help', help="Output this help message and exit.")
    arg_parser.add_argument('dir', metavar='DIR', help="The restricted directory to use.")
    args = arg_parser.parse_args()
    args.dir = os.path.realpath(args.dir)
    args.dir_slash = args.dir + '/'
    args.dir_slash_len = len(args.dir_slash)
    if args.ro:
        args.no_del = True
    elif not args.no_lock:
        lock_or_die(args.dir)
    main()

# vim: sw=4 et

cmd: