mount.davfs (8)

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/pathrs040withrs040spaces 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) <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=[]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

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 asciigirl.com/webdav at mount point /mount/site, encrypting all traffic with SSL. Credentials for 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 asciigirl.com/webdav /mount/site

Mounts the resource linux.org.ar/repos at /dav.

mount.davfs -o uid=otto,gid=users,mode=775 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

savannah.nongnu.org/projects/davfs2

SEE ALSO

umount.davfs(8), davfs2.conf(5), mount(8), umount(8), fstab(5)