Ubuntu Manpage: mount.davfs - Mount a WebDAV resource as davfs2 file system

NAME

       mount.davfs - Mount a WebDAV resource as davfs2 file system

SYNOPSIS

       mount.davfs [-h | --help] [-V | --version]
       mount {dir | webdavserver}

SYNOPSIS (root only)

       mount -t davfs [-o option[,...]] webdavserver dir
       mount.davfs [-o option[,...]] webdavserver dir

DESCRIPTION

mount.davfs allows you to mount the WebDAV resource identified by webdavserver into the
local filesystem at dir. WebDAV is an extension to HTTP that allows remote, collaborative
authoring of Web resources, defined in RFC 4918. mount.davfs is part of davfs2.

davfs2 allows documents on a remote Web server to be edited using standard applications.
For example, a remote Web site could be updated in-place using the same development tools
that initially created the site. Or you may use a WebDAV resource for documents you want
to access and edited from different locations.

davfs2 supports TLS/SSL (if the neon library supports it) and proxies. mount.davfs runs as
a daemon in userspace. It integrates into the virtual file system by either the coda or
the fuse kernel files system. Currently CODA_KERNEL_VERSION 3 and FUSE_KERNEL_VERSION 7
are supported.

mount.davfs is usually invoked by the mount(8) command when using the -t davfs option.
After mounting it runs as a daemon. To unmount the umount(8) command is used.

webdavserver is the URL of the server. It must at least contain the host name. It may
additionally contain the scheme, the port and the path. Missing components are set to
sensible default values. The path component must not be %-encoded, but when entering the
URL at the command line or in /etc/fstab the escaping rules of the shell or fstab must be
obeyed.

dir is the mountpoint where the WebDAV resource is mounted on. It may be an absolute or
relative path.

fstab may be used to define mounts and mount options as usual. In place of the device the
url of the WebDAV server must be given. There must not be more than one entry in fstab for
every mountpoint.

OPTIONS

-V --version
Output version.

-h --help
Print a help message.

-o A comma-separated list defines mount options to be used. Available options are:

[no]auto
Can (not) be mounted with mount -a.
Default: auto.

comment=some comment
This option is ignored by mount.davfs but other programs may require it to
be present in fstab.

conf=absolute path
An alternative user configuration file. This option is intended for cases
where the default user configuration file in the users home directory can
not be used.
Default: ~/.davfs2/davfs2.conf

[no]dev
(Do not) interpret character or block special devices on the file system.
This option is only included for compatibility with the mount(8) program. It
will allways be set to nodev

dir_mode=mode
The default mode bits for directories in the mounted file system. Value
given in octal. s-bits for user and group are allways silently ignored.
Default: calculated from the umask of the mounting user; an x-bit is
associated to every r-bit in u-g-o.

[no]exec
(Do not) allow execution of any binaries on the mounted file system.
Default: exec. (When mounting as an ordinary user, the mount(8) program will
set the default to noexec.)

file_mode=mode
The default mode bits for files in the mounted file system. Value given in
octal. s-bits for user and group are allways silently ignored.
Default: calculated from the umask of the mounting user; no x-bits are set
for files.

gid=group
The group the mounted file system belongs to. It may be a numeric ID or a
group name. The mounting user, if not root, must be member of this group.
Default: the primary group of the mounting user.

[no]grpid
When this option is set a newly created file will take the group id of the
directory in which it is created. This will also apply to all files that are
on the server and not in the local cache. (That is because the group id is
not stored on the server.)
If the group id of the directory is root this option is ignored.
Default: nogrpid.

[no]_netdev
The file system needs a (no) network connection for operation. This
information allows the operating system to handle the file system properly
at system start and when the network is shut down.
Default: _netdev

ro Mount the file system read-only.
Default: rw.

rw Mount the file system read-write.
Default: rw.

[no]suid
Do not allow set-user-identifier or set-group-identifier bits to take
effect. This option is only included for compatibility with the mount
program. It will allways be set to nosuid.

[no]user
(Do not) allow an ordinary user to mount the file system. The name of
the mounting user is written to mtab so that he can unmount the file system
again. Option user implies the options noexec, nosuid and nodev (unless
overridden by subsequent options). This option makes only sense when set in
fstab.
Default: ordinary users are not allowed to mount.

users Like user, but any user is allowed to unmount the file system, not only the
mounting user. This is generally not recomended. If the user option allows
an unprivileged user to mount, but unmounting by the mounting user fails the
users may be a work around.
Default: only the mounting user is allowed to unmount the file system.

uid=user
The owner of the mounted file system. It may be a numeric ID or a user name.
Only when mounted by root, this may be different from the mounting user.
Default: ID of the mounting user.

username=WebDAV_user
Use this name to authenticate with the WebDAV server. This option is intended for
use with pam_mount only. When this option is set the credentials in the secrets
files will be ignored. The password will always be read from stdin, even when
option askauth is set to 0. Do not use it in fstab. The username will be visible
for everyone in the output of ps.
Default: no username.
Experimental: This option is experimental and might be removed. If you think it
useful and successfully use it please send a short report.

SECURITY POLICY

mount.davfs needs root privileges for mounting. But running a daemon, that is connected to
the internet, with root privileges is a security risk. So mount.davfs will change its uid
and gid when entering daemon mode.

When invoked by root mount.davfs will run as user davfs2 and group davfs2. This may
be changed in /etc/davfs2/davfs2.conf.

When invoked by an ordinary user it will run with the id of this user and with
group davfs2.

As the file system may be mounted over an insecure internet connection, this increases the
risk that malicious content may be included in the file system. So mount.davfs is slightly
more restrictive than mount(8).

Options nosuid and nodev will always be set; even root can not change this.

For ordinary users to be able to mount, they must be member of group davfs2 and
there must be an entry in fstab.

When the mount point given in fstab is a relative file name and the file system is
mounted by an unprivileged user, the mount point must lie within the home directory
of the mounting user.

If in fstab option uid and/or gid are given, an ordinary user can only mount, if
her uid is the one given in option uid and he belongs to the group given in option
gid.

WARNING: If root allows an ordinary user to mount a file system (using fstab) this
includes the permission to read the associated credentials from /etc/davfs2/secrets as
well as the private key of the associated client certificate and the mounting user may get
access to this information. You should only do this, if you might as well give this
information to the user directly.

URLS AND MOUNT POINTS WITH SPACES

       Special  characters  like spaces in pathnames are a mess. They are interpreted differently
       by different programs and protocols, and there are different rules for escaping.

       In fstab  spaces  must  be  replaced  by  a  three  digit  octal  escape  sequence.  Write
       http://foo.bar/path\040with\040spaces instead of http://foo.bar/path with spaces.

       For  the  davfs2.conf  and  the  secrets  files  please see the escape and quotation rules
       described in the davfs2.conf(5) man page.

       On command line you must obey the escaping rules of the shell.

CACHING

       mount.davfs tries to reduce HTTP-trafic by caching and reusing  data.   Information  about
       directories and files are held in memory, while downloaded files are cached on disk.

       mount.davfs  needs  to  hold a local copy of all open files in the cache directory. Please
       make sure that enough local disk space is available.

       mount.davfs will consider cached information about directories and file  attributes  valid
       for  a  configurable  time and look up this information on the server only after this time
       has expired (or there is other evidence that this information is stale).  So  if  somebody
       else  creates  or  deletes files on the server it may take some time before the local file
       system reflects this.

       This will not affect the content of files and  directory  listings.  Whenever  a  file  is
       opened,  the  server  is  looked  up  for a newer version of the file.  Please consult the
       manual davfs2.conf(5) to see how can you configure this according your needs.

LOCKS, LOST UPDATE PROBLEM AND BACKUP FILES

WebDAV introduced locks and mount.davfs uses them by default. This will in most cases
prevent two people from changing the same file in parallel. But not allways:

You might have disabled locks in /etc/davfs2/davfs2.conf or ~/.davfs2/davfs2.conf.

The server might not support locks (they are not mandatory).

A bad connection might prevent mount.davfs from refreshing the lock in time.

Another WebDAV-client might use your lock (that is not too difficult and might even
happen without intention).

mount.davfs will therefore check if the file has been changed on the the server before it
uploads a new version. If it finds it impossible to upload the locally changed file, it
will store it in the local backup direcotry lost+found. You should check this directory
from time to time and decide what to do with this files.

Sometimes locks held by some client on the server will not be released. Maybe the client
crashes or the network connection fails. When mount.davfs finds a file locked on the
server, it will check whether the lock is held by mount.davfs and the current user, and if
so tries to reuse and release it. But this will not allways succeed. So servers should
automatically release locks after some time, when they are not refreshed by the client.

WebDAV allows to lock files that don't exist (to protect the name when a client intends to
create a new file). This locks will be displayed as files with size 0 and last modified
date of 1970-01-01. If this locks are not released properly mount.davfs may not be able to
access this files. You can use cadaver(1) <http://www.webdav.org/cadaver/> to remove this
locks.

FILE OWNER AND PERMISSIONS

       davfs2  implements Unix permissions for access control. But changing owner and permissions
       of a file is only local. It is intended as a means for the owner of the  file  system,  to
       controll whether other local users may acces this file system.

       The server does not know about this. From the servers point of view there is just one user
       (identified by the credentials) connected. Another WebDAV-client, connected  to  the  same
       server, is not affected by this local changes.

       There  is one exeption: The execute bit on files is stored as a property on the sever. You
       may think of this property as an  information  about  the  type  of  file  rather  than  a
       permission.  Whether  the  file  is  executable on the local system is still controlled by
       mount options and local permissions.

       When the file system is  unmounted,  attributes  of  cached  files  (including  owner  and
       permissions) are stored in cache, as well as the attributs of the direcotries they are in.
       But there is no information stored about directories that do not contain cached files.

FILES

/etc/davfs2/davfs2.conf
System wide configuration file.

~/.davfs2/davfs2.conf
Configuration file in the users home directory.The user configuration takes
precedence over the system wide configuration. If it does not exist, mount.davfs
will will create a template file.

/etc/davfs2/secrets
Holds the credentials for WebDAV servers and the proxy, as well as decryption
passwords for client certificates. The file must be read-writable by root only.

~/.davfs2/secrets
Holds credentials for WebDAV servers and proxy, as well as decryption passwords for
client certificates. The file must be read-writable by the owner only. Credentials
are first looked up in the home directory of the mounting user. If not found there
the system wide secrets file is consulted. If no creditentials and passwords are
found they are asked from the user interactively (if not disabled). If the file
does not exist, mount.davfs will will create a template file.

/etc/davfs2/certs
You may store trusted server certificates here, that can not be verified by use of
the system wide CA-Certificates. This is useful when your server uses a selfmade
certificate. You must configure the servercert option in /etc/davfs2/davfs2.conf or
~/.davfs2/davfs2.conf to use it. Certificates must be in PEM format.
Be sure to verify the certificate.

~/.davfs2/certs
You may store trusted server certificates here, that can not be verified by use of
the system wide CA-Certificates. This is useful when your server uses a selfmade
certificate. You must configure the servercert option in ~/.davfs2/davfs2.conf to
use it. Certificates must be in PEM format.
Be sure to verify the certificate.

/etc/davfs2/certs/private
To store client certificates. Certificates must be in PKCS#12 format. You must
configure the clientcert option in /etc/davfs2/davfs2.conf or ~/.davfs2/davfs2.conf
to use it. This directory must be rwx by root only.

~/.davfs2/certs/private
To store client certificates. Certificates must be in PKCS#12 format. You must
configure the clientcert option in ~/.davfs2/davfs2.conf to use it. This directory
must be rwx by the owner only.

/var/run/mount.davfs
PID-files of running mount.davfs processes are stored there. This directory must
belong to group davfs2 with write permissions for the group and the sticky-bit set
(mode 1775). The PID-files are named after the mount point of the file system.

/var/cache/davfs2
System wide directory for cached files. Used when the file system is mounted by
root. It must belong do group davfs2 and read, write and execute bits for group
must be set. There is a subdirectory for every mounted file system. The names of
this subdirectories are created from url, mount point and user name.

~/.davfs2/cache
Cache directory in the mounting users home directory. For every mounted WebDAV
resource a subdirectory is created.

mount.davfs will try to create missing directories, but it will not touch /etc/davfs2.

ENVIRONMENT

       https_proxy http_proxy all_proxy
              If no proxy is defined in the configuration file  the  value  is  taken  from  this
              environment  variables.  The  proxy may be given with or without scheme and with or
              without port
              http_proxy=[http://]foo.bar[:3218]
              Only used when the mounting user is root.

       no_proxy
              A comma separated list of domain names that shall be accessed directly.  *  matches
              any domain name. A domain name starting with .  (period) matches all subdomains.
              Only used when the mounting user is root.
              Not applied when the proxy is defined in /etc/davfs2.

EXAMPLES

       Non root user (e.g. filomena):

       To allow an ordinary user to mount there must be an entry in fstab
              http://webdav.org/dav   /media/dav   davfs   noauto,user   0   0

       If a proxy must be used this should be configured in /etc/davfs2/davfs2.conf
              proxy   proxy.mycompany.com:8080

       Credentials are stored in /home/filomena/.davfs2/secrets
              proxy.mycompany.com     filomena  "my secret"
              /media/dav   webdav-username   password

       Now the WebDAV resource may be mounted by user filomena invoking
              mount /media/dav

       and unmounted by user filomena invoking
              umount /media/dav

       Root user only:

       Mounts  the  resource  https://asciigirl.com/webdav at mount point /mount/site, encrypting
       all traffic  with  SSL.  Credentials  for  http://webdav.org/dav  will  be  looked  up  in
       /etc/davfs2/secrets, if not found there the user will be asked.
              mount   -t   davfs   -o   uid=otto,gid=users,mode=775  https://asciigirl.com/webdav
              /mount/site

       Mounts the resource http://linux.org.ar/repos at /dav.
              mount.davfs -o uid=otto,gid=users,mode=775 http://linux.org.ar/repos/ /dav

BUGS

       davfs2 does not support links.

       A davfs2 file system cannot be moved with mount --move.

AUTHORS

       This man page was written by Luciano Bello <luciano@linux.org.ar> for Debian, for  version
       0.2.3 of davfs2.

       It has been updated for this version by Werner Baumann <werner.baumann@onlinhome.de>.

       davfs2 is developed by Sung Kim <hunkim@gmail.com>.

       Version 1.0.0 (and later) of davfs2 is a complete rewrite by Werner Baumann.

DAVFS2 HOME

       http://savannah.nongnu.org/projects/davfs2