pure-uploadscript - Automatically run an external program after a
pure-uploadscript [-p </path/to/pidfile>] [-B] [-g <gid>] [-h] -r
<program to run> [-u <uid>]
If Pure-FTPd is compiled with --with-uploadscript (default in binary
distributions), and if the -o (or --uploadscript) is passed to the
server, a named pipe called /var/run/pure-ftpd.upload.pipe is created.
You will also notice an important file called
/var/run/pure-ftpd.upload.lock, used for locking.
After a successful upload, the file name is written to the pipe.
pure-uploadscript reads this pipe to automatically run any program or
script to process the newly uploaded file.
-B Daemonize the process and fork it in background.
Switch the group ID to <gid>.
-h or --help
Display available options.
-r <program to run>
Tell what program/script to run. It has to be an absolute
filename, the PATH environment variable is ignored. The first
argument of that program will be the unquoted name of the newly
uploaded file. Environment variables aren’t cleared. So don’t
put sensitive data in them before calling pure-uploadscript if
you switch uid.
Switch the user ID to <uid>.
When the upload script is run, the name of the newly uploaded file is
the first argument passed to the script (referenced as $1 by most
shells) . Some environment variables are also filled by useful info
about the file. UPLOAD_SIZE The size of the file, in bytes.
UPLOAD_PERMS The permissions, as an octal integer. UPLOAD_UID The
numerical UID of the owner. UPLOAD_GID The numerical GID of the owner.
UPLOAD_USER The login of the owner. UPLOAD_GROUP The group name the
files belongs to. UPLOAD_VUSER The full user name, or the virtual user
name (127 chars max) .
pure-ftpd and pure-uploadscript are trying to limit security
implications of such a feature.
- The pipe can only be created and opened by root. It must have perms
600, with uid 0, or it will be ignored.
- The argument passed to an external program/script is always an exact
absolute path name. It doesn’t get fooled by chroot()ed environments,
and by absolute or relative paths added to the STOR command.
- UID and GID are set just after parsing command-line options, and
pure-uploadscript never gets back supervisor privileges.
- Descriptors to the pipe are never passed to external
programs/scripts. So when UID switched, the target user can’t mess the
- Only regular files are processed, control characters are rejected,
and a header+footer avoid partial file names.
- Two external programs/scripts can’t run at the same time. Uploads are
always processed sequentially, in chronological order. This is to avoid
denial-of-services by issuing a lot of simultaneous STOR commands in
order to launch a fork bomb on the server. For this reason, your
programs shouldn’t take a long time to complete (but they can run
themselves in background) .
A sample script could be :
echo "$1 uploaded" | /usr/bin/mutt -s "New upload : $1" \
Never forget to quote ("variable") all variables in all your shell
scripts to avoid security flaws.
Frank DENIS <j at pureftpd dot org>
ftp(1), pure-ftpd(8) pure-ftpwho(8) pure-mrtginfo(8) pure-
uploadscript(8) pure-statsdecode(8) pure-pw(8) pure-quotacheck(8) pure-
RFC 959, RFC 2228, RFC 2389 and RFC 2428.