Andrew Tridgell
c1d8cc1c04
The %H allow-list was wrong in both directions.
Several accepted characters change an argument's MEANING rather than its
text when they lead the value, which quoting cannot prevent because the
word stays intact -- that IS the problem:
'-' and '+' introduce options to plenty of programs; with
RSYNC_CONNECT_PROG="prog %H", hosts "-c" and "+x" arrive as
options, and "sh +x" is as real as "sh -x";
'~' is tilde-expanded by the nested shell, turning ~root into /root;
'%' is expanded by a nested fish, where %self becomes its pid.
An empty host has the same shape from the other end: it survives a direct
exec as an empty argument but disappears when a nested shell re-splits the
command, shifting everything after it. rsync://:873/m/ and ::m/ both
produce one. None of these can begin a real hostname, so refuse them in
first position only -- mid-word each is literal, which matters because an
IPv6 zone id carries its '%' mid-word.
The other direction: '+' and '~' were refused outright. They execute
nothing, and RSYNC_CONNECT_PROG exists for custom transports where %H is
often an alias the program resolves itself rather than a name the
resolver sees. Refusing them mid-word breaks that use case for no gain.
A non-ASCII host stays refused. That is a policy choice rather than a
free one: a custom connect program never calls getaddrinfo, so a Unicode
alias would otherwise work, and this does exclude it. A punycode A-label
is unaffected.
What this cannot do is bound what the named program makes of the value.
"host:-rf" arrives intact, and a program that splits on ':' may
reinterpret the tail; that boundary belongs to whoever writes the
command.
The test asserted only that a marker file was absent -- equally true when
rsync failed to parse its arguments, when socketpair_tcp is blocked, or
when touch was missing. Worse, the marker path was absolute, and a URL
authority ends at the first '/', so the injected `touch` never received
an operand and the check could not fail even with the guard gone. It now
runs with cwd set to the scratch directory and injects a bare name, so
the marker is genuinely reachable; requires the specific refusal message;
checks the exit status; and checks that ordinary hosts still arrive at
the connect program with their text intact, which is the part an
absence-only test can never show.
Fault-injected separately: dropping the guard, dropping just the
first-character check, and narrowing the set back each fail the test on
their own, in both the default and --use-tcp transports.
(cherry picked from commit dcc3c9c51a)
# Conflicts:
# testsuite/connect-prog-nested-singlequote-host-injection_test.py
WHAT IS RSYNC?
Rsync is a fast and extraordinarily versatile file copying tool for both remote and local files.
Rsync uses a delta-transfer algorithm which provides a very fast method for bringing remote files into sync. It does this by sending just the differences in the files across the link, without requiring that both sets of files are present at one of the ends of the link beforehand. At first glance this may seem impossible because the calculation of diffs between two files normally requires local access to both files.
A technical report describing the rsync algorithm is included with this package.
USAGE
Basically you use rsync just like scp, but rsync has many additional options. To get a complete list of supported options type:
rsync --help
See the manpage for more detailed information.
BUILDING AND INSTALLING
If you need to build rsync yourself, check out the INSTALL page for information on what libraries and packages you can use to get the maximum features in your build.
SETUP
Rsync normally uses ssh or rsh for communication with remote systems. It does not need to be setuid and requires no special privileges for installation. You must, however, have a working ssh or rsh system. Using ssh is recommended for its security features.
Alternatively, rsync can run in `daemon' mode, listening on a socket. This is generally used for public file distribution, although authentication and access control are available.
To install rsync, first run the "configure" script. This will create a Makefile and config.h appropriate for your system. Then type "make".
Note that on some systems you will have to force configure not to use gcc because gcc may not support some features (such as 64 bit file offsets) that your system may support. Set the environment variable CC to the name of your native compiler before running configure in this case.
Once built put a copy of rsync in your search path on the local and remote systems (or use "make install"). That's it!
RSYNC DAEMONS
Rsync can also talk to "rsync daemons" which can provide anonymous or authenticated rsync. See the rsyncd.conf(5) manpage for details on how to setup an rsync daemon. See the rsync(1) manpage for info on how to connect to an rsync daemon.
WEB SITE
For more information, visit the main rsync web site.
You'll find a FAQ list, downloads, resources, HTML versions of the manpages, etc.
MAILING LISTS
There is a mailing list for the discussion of rsync and its applications that is open to anyone to join. New releases are announced on this list, and there is also an announcement-only mailing list for those that want official announcements. See the mailing-list page for full details.
BUG REPORTS
The bug-tracking web page has full details on bug reporting.
That page contains links to the current bug list, and information on how to do a good job when reporting a bug. You might also like to try searching the Internet for the error message you've received, or looking in the mailing list archives.
To send a bug report, follow the instructions on the bug-tracking page of the web site.
Alternately, email your bug report to rsync@lists.samba.org.
GIT REPOSITORY
If you want to get the very latest version of rsync direct from the source code repository, then you will need to use git. The git repo is hosted on GitHub and on Samba's site.
See the download page for full details on all the ways to grab the source.
COPYRIGHT
Rsync was originally written by Andrew Tridgell. It has been improved by many developers from around the world.
Special thanks go to Wayne Davison, who maintained rsync from 2004 to 2024.
Rsync may be used, modified and redistributed only under the terms of the GNU General Public License, found in the file COPYING in this distribution, or at the Free Software Foundation.