virtiofsd: Remove source

Now remove all the source.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 0 insertions, 403 deletions

diff --git a/docs/tools/virtiofsd.rst b/docs/tools/virtiofsd.rst
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-QEMU virtio-fs shared file system daemon
-========================================
-
-Synopsis
---------
-
-**virtiofsd** [*OPTIONS*]
-
-Description
------------
-
-Share a host directory tree with a guest through a virtio-fs device.  This
-program is a vhost-user backend that implements the virtio-fs device.  Each
-virtio-fs device instance requires its own virtiofsd process.
-
-This program is designed to work with QEMU's ``--device vhost-user-fs-pci``
-but should work with any virtual machine monitor (VMM) that supports
-vhost-user.  See the Examples section below.
-
-This program must be run as the root user.  The program drops privileges where
-possible during startup although it must be able to create and access files
-with any uid/gid:
-
-* The ability to invoke syscalls is limited using seccomp(2).
-* Linux capabilities(7) are dropped.
-
-In "namespace" sandbox mode the program switches into a new file system
-namespace and invokes pivot_root(2) to make the shared directory tree its root.
-A new pid and net namespace is also created to isolate the process.
-
-In "chroot" sandbox mode the program invokes chroot(2) to make the shared
-directory tree its root. This mode is intended for container environments where
-the container runtime has already set up the namespaces and the program does
-not have permission to create namespaces itself.
-
-Both sandbox modes prevent "file system escapes" due to symlinks and other file
-system objects that might lead to files outside the shared directory.
-
-Options
--------
-
-.. program:: virtiofsd
-
-.. option:: -h, --help
-
-  Print help.
-
-.. option:: -V, --version
-
-  Print version.
-
-.. option:: -d
-
-  Enable debug output.
-
-.. option:: --syslog
-
-  Print log messages to syslog instead of stderr.
-
-.. option:: -o OPTION
-
-  * debug -
-    Enable debug output.
-
-  * flock|no_flock -
-    Enable/disable flock.  The default is ``no_flock``.
-
-  * modcaps=CAPLIST
-    Modify the list of capabilities allowed; CAPLIST is a colon separated
-    list of capabilities, each preceded by either + or -, e.g.
-    ''+sys_admin:-chown''.
-
-  * log_level=LEVEL -
-    Print only log messages matching LEVEL or more severe.  LEVEL is one of
-    ``err``, ``warn``, ``info``, or ``debug``.  The default is ``info``.
-
-  * posix_lock|no_posix_lock -
-    Enable/disable remote POSIX locks.  The default is ``no_posix_lock``.
-
-  * readdirplus|no_readdirplus -
-    Enable/disable readdirplus.  The default is ``readdirplus``.
-
-  * sandbox=namespace|chroot -
-    Sandbox mode:
-    - namespace: Create mount, pid, and net namespaces and pivot_root(2) into
-    the shared directory.
-    - chroot: chroot(2) into shared directory (use in containers).
-    The default is "namespace".
-
-  * source=PATH -
-    Share host directory tree located at PATH.  This option is required.
-
-  * timeout=TIMEOUT -
-    I/O timeout in seconds.  The default depends on cache= option.
-
-  * writeback|no_writeback -
-    Enable/disable writeback cache. The cache allows the FUSE client to buffer
-    and merge write requests.  The default is ``no_writeback``.
-
-  * xattr|no_xattr -
-    Enable/disable extended attributes (xattr) on files and directories.  The
-    default is ``no_xattr``.
-
-  * posix_acl|no_posix_acl -
-    Enable/disable posix acl support.  Posix ACLs are disabled by default.
-
-  * security_label|no_security_label -
-    Enable/disable security label support. Security labels are disabled by
-    default. This will allow client to send a MAC label of file during
-    file creation. Typically this is expected to be SELinux security
-    label. Server will try to set that label on newly created file
-    atomically wherever possible.
-
-  * killpriv_v2|no_killpriv_v2 -
-    Enable/disable ``FUSE_HANDLE_KILLPRIV_V2`` support. KILLPRIV_V2 is enabled
-    by default as long as the client supports it. Enabling this option helps
-    with performance in write path.
-
-.. option:: --socket-path=PATH
-
-  Listen on vhost-user UNIX domain socket at PATH.
-
-.. option:: --socket-group=GROUP
-
-  Set the vhost-user UNIX domain socket gid to GROUP.
-
-.. option:: --fd=FDNUM
-
-  Accept connections from vhost-user UNIX domain socket file descriptor FDNUM.
-  The file descriptor must already be listening for connections.
-
-.. option:: --thread-pool-size=NUM
-
-  Restrict the number of worker threads per request queue to NUM.  The default
-  is 0.
-
-.. option:: --cache=none|auto|always
-
-  Select the desired trade-off between coherency and performance.  ``none``
-  forbids the FUSE client from caching to achieve best coherency at the cost of
-  performance.  ``auto`` acts similar to NFS with a 1 second metadata cache
-  timeout.  ``always`` sets a long cache lifetime at the expense of coherency.
-  The default is ``auto``.
-
-Extended attribute (xattr) mapping
-----------------------------------
-
-By default the name of xattr's used by the client are passed through to the server
-file system.  This can be a problem where either those xattr names are used
-by something on the server (e.g. selinux client/server confusion) or if the
-``virtiofsd`` is running in a container with restricted privileges where it
-cannot access some attributes.
-
-Mapping syntax
-~~~~~~~~~~~~~~
-
-A mapping of xattr names can be made using -o xattrmap=mapping where the ``mapping``
-string consists of a series of rules.
-
-The first matching rule terminates the mapping.
-The set of rules must include a terminating rule to match any remaining attributes
-at the end.
-
-Each rule consists of a number of fields separated with a separator that is the
-first non-white space character in the rule.  This separator must then be used
-for the whole rule.
-White space may be added before and after each rule.
-
-Using ':' as the separator a rule is of the form:
-
-``:type:scope:key:prepend:``
-
-**scope** is:
-
-- 'client' - match 'key' against a xattr name from the client for
-             setxattr/getxattr/removexattr
-- 'server' - match 'prepend' against a xattr name from the server
-             for listxattr
-- 'all' - can be used to make a single rule where both the server
-          and client matches are triggered.
-
-**type** is one of:
-
-- 'prefix' - is designed to prepend and strip a prefix;  the modified
-  attributes then being passed on to the client/server.
-
-- 'ok' - Causes the rule set to be terminated when a match is found
-  while allowing matching xattr's through unchanged.
-  It is intended both as a way of explicitly terminating
-  the list of rules, and to allow some xattr's to skip following rules.
-
-- 'bad' - If a client tries to use a name matching 'key' it's
-  denied using EPERM; when the server passes an attribute
-  name matching 'prepend' it's hidden.  In many ways it's use is very like
-  'ok' as either an explicit terminator or for special handling of certain
-  patterns.
-
-- 'unsupported' - If a client tries to use a name matching 'key' it's
-  denied using ENOTSUP; when the server passes an attribute
-  name matching 'prepend' it's hidden.  In many ways it's use is very like
-  'ok' as either an explicit terminator or for special handling of certain
-  patterns.
-
-**key** is a string tested as a prefix on an attribute name originating
-on the client.  It maybe empty in which case a 'client' rule
-will always match on client names.
-
-**prepend** is a string tested as a prefix on an attribute name originating
-on the server, and used as a new prefix.  It may be empty
-in which case a 'server' rule will always match on all names from
-the server.
-
-e.g.:
-
-  ``:prefix:client:trusted.:user.virtiofs.:``
-
-  will match 'trusted.' attributes in client calls and prefix them before
-  passing them to the server.
-
-  ``:prefix:server::user.virtiofs.:``
-
-  will strip 'user.virtiofs.' from all server replies.
-
-  ``:prefix:all:trusted.:user.virtiofs.:``
-
-  combines the previous two cases into a single rule.
-
-  ``:ok:client:user.::``
-
-  will allow get/set xattr for 'user.' xattr's and ignore
-  following rules.
-
-  ``:ok:server::security.:``
-
-  will pass 'security.' xattr's in listxattr from the server
-  and ignore following rules.
-
-  ``:ok:all:::``
-
-  will terminate the rule search passing any remaining attributes
-  in both directions.
-
-  ``:bad:server::security.:``
-
-  would hide 'security.' xattr's in listxattr from the server.
-
-A simpler 'map' type provides a shorter syntax for the common case:
-
-``:map:key:prepend:``
-
-The 'map' type adds a number of separate rules to add **prepend** as a prefix
-to the matched **key** (or all attributes if **key** is empty).
-There may be at most one 'map' rule and it must be the last rule in the set.
-
-Note: When the 'security.capability' xattr is remapped, the daemon has to do
-extra work to remove it during many operations, which the host kernel normally
-does itself.
-
-Security considerations
-~~~~~~~~~~~~~~~~~~~~~~~
-
-Operating systems typically partition the xattr namespace using
-well defined name prefixes. Each partition may have different
-access controls applied. For example, on Linux there are multiple
-partitions
-
- * ``system.*`` - access varies depending on attribute & filesystem
- * ``security.*`` - only processes with CAP_SYS_ADMIN
- * ``trusted.*`` - only processes with CAP_SYS_ADMIN
- * ``user.*`` - any process granted by file permissions / ownership
-
-While other OS such as FreeBSD have different name prefixes
-and access control rules.
-
-When remapping attributes on the host, it is important to
-ensure that the remapping does not allow a guest user to
-evade the guest access control rules.
-
-Consider if ``trusted.*`` from the guest was remapped to
-``user.virtiofs.trusted*`` in the host. An unprivileged
-user in a Linux guest has the ability to write to xattrs
-under ``user.*``. Thus the user can evade the access
-control restriction on ``trusted.*`` by instead writing
-to ``user.virtiofs.trusted.*``.
-
-As noted above, the partitions used and access controls
-applied, will vary across guest OS, so it is not wise to
-try to predict what the guest OS will use.
-
-The simplest way to avoid an insecure configuration is
-to remap all xattrs at once, to a given fixed prefix.
-This is shown in example (1) below.
-
-If selectively mapping only a subset of xattr prefixes,
-then rules must be added to explicitly block direct
-access to the target of the remapping. This is shown
-in example (2) below.
-
-Mapping examples
-~~~~~~~~~~~~~~~~
-
-1) Prefix all attributes with 'user.virtiofs.'
-
-::
-
- -o xattrmap=":prefix:all::user.virtiofs.::bad:all:::"
-
-
-This uses two rules, using : as the field separator;
-the first rule prefixes and strips 'user.virtiofs.',
-the second rule hides any non-prefixed attributes that
-the host set.
-
-This is equivalent to the 'map' rule:
-
-::
-
- -o xattrmap=":map::user.virtiofs.:"
-
-2) Prefix 'trusted.' attributes, allow others through
-
-::
-
-   "/prefix/all/trusted./user.virtiofs./
-    /bad/server//trusted./
-    /bad/client/user.virtiofs.//
-    /ok/all///"
-
-
-Here there are four rules, using / as the field
-separator, and also demonstrating that new lines can
-be included between rules.
-The first rule is the prefixing of 'trusted.' and
-stripping of 'user.virtiofs.'.
-The second rule hides unprefixed 'trusted.' attributes
-on the host.
-The third rule stops a guest from explicitly setting
-the 'user.virtiofs.' path directly to prevent access
-control bypass on the target of the earlier prefix
-remapping.
-Finally, the fourth rule lets all remaining attributes
-through.
-
-This is equivalent to the 'map' rule:
-
-::
-
- -o xattrmap="/map/trusted./user.virtiofs./"
-
-3) Hide 'security.' attributes, and allow everything else
-
-::
-
-    "/bad/all/security./security./
-     /ok/all///'
-
-The first rule combines what could be separate client and server
-rules into a single 'all' rule, matching 'security.' in either
-client arguments or lists returned from the host.  This stops
-the client seeing any 'security.' attributes on the server and
-stops it setting any.
-
-SELinux support
----------------
-One can enable support for SELinux by running virtiofsd with option
-"-o security_label". But this will try to save guest's security context
-in xattr security.selinux on host and it might fail if host's SELinux
-policy does not permit virtiofsd to do this operation.
-
-Hence, it is preferred to remap guest's "security.selinux" xattr to say
-"trusted.virtiofs.security.selinux" on host.
-
-"-o xattrmap=:map:security.selinux:trusted.virtiofs.:"
-
-This will make sure that guest and host's SELinux xattrs on same file
-remain separate and not interfere with each other. And will allow both
-host and guest to implement their own separate SELinux policies.
-
-Setting trusted xattr on host requires CAP_SYS_ADMIN. So one will need
-add this capability to daemon.
-
-"-o modcaps=+sys_admin"
-
-Giving CAP_SYS_ADMIN increases the risk on system. Now virtiofsd is more
-powerful and if gets compromised, it can do lot of damage to host system.
-So keep this trade-off in my mind while making a decision.
-
-Examples
---------
-
-Export ``/var/lib/fs/vm001/`` on vhost-user UNIX domain socket
-``/var/run/vm001-vhost-fs.sock``:
-
-.. parsed-literal::
-
-  host# virtiofsd --socket-path=/var/run/vm001-vhost-fs.sock -o source=/var/lib/fs/vm001
-  host# |qemu_system| \\
-        -chardev socket,id=char0,path=/var/run/vm001-vhost-fs.sock \\
-        -device vhost-user-fs-pci,chardev=char0,tag=myfs \\
-        -object memory-backend-memfd,id=mem,size=4G,share=on \\
-        -numa node,memdev=mem \\
-        ...
-  guest# mount -t virtiofs myfs /mnt