Merge remote-tracking branch 'remotes/dgilbert-gitlab/tags/pull-virti…

…ofs-20201026' into staging

virtiofsd pull 2020-10-26

Misono
   Set default log level to info
   Explicit build option for virtiofsd

Me
   xattr name mapping

Stefan
  Alternative chroot sandbox method

Max
  Submount mechanism

Signed-off-by: Dr. David Alan Gilbert <[email protected]>

# gpg: Signature made Mon 26 Oct 2020 18:41:36 GMT
# gpg:                using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <[email protected]>" [full]
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert-gitlab/tags/pull-virtiofs-20201026:
  tests/acceptance: Add virtiofs_submounts.py
  tests/acceptance/boot_linux: Accept SSH pubkey
  virtiofsd: Announce sub-mount points
  virtiofsd: Store every lo_inode's parent_dev
  virtiofsd: Add fuse_reply_attr_with_flags()
  virtiofsd: Add attr_flags to fuse_entry_param
  virtiofsd: Announce FUSE_ATTR_FLAGS
  linux/fuse.h: Pull in from Linux
  tools/virtiofsd: xattr name mappings: Simple 'map'
  tools/virtiofsd: xattr name mapping examples
  tools/virtiofsd: xattr name mappings: Map server xattr names
  tools/virtiofsd: xattr name mappings: Map client xattr names
  tools/virtiofsd: xattr name mappings: Add option
  virtiofsd: add container-friendly -o sandbox=chroot option
  virtiofsd: passthrough_ll: set FUSE_LOG_INFO as default log_level
  configure: add option for virtiofsd

Signed-off-by: Peter Maydell <[email protected]>

configure

@@ -302,6 +302,7 @@ fdt="auto"
 netmap="no"
 sdl="auto"
 sdl_image="auto"
+virtiofsd="auto"
 virtfs=""
 libudev="auto"
 mpath="auto"
@@ -999,6 +1000,10 @@ for opt do
   ;;
   --enable-libudev) libudev="enabled"
   ;;
+  --disable-virtiofsd) virtiofsd="disabled"
+  ;;
+  --enable-virtiofsd) virtiofsd="enabled"
+  ;;
   --disable-mpath) mpath="disabled"
   ;;
   --enable-mpath) mpath="enabled"
@@ -1758,6 +1763,7 @@ disabled with --disable-FEATURE, default is enabled if available:
   vnc-png         PNG compression for VNC server
   cocoa           Cocoa UI (Mac OS X only)
   virtfs          VirtFS
+  virtiofsd       build virtiofs daemon (virtiofsd)
   libudev         Use libudev to enumerate host devices
   mpath           Multipath persistent reservation passthrough
   xen             xen backend driver support
@@ -6972,7 +6978,7 @@ NINJA=$ninja $meson setup \
         -Dxen=$xen -Dxen_pci_passthrough=$xen_pci_passthrough -Dtcg=$tcg \
         -Dcocoa=$cocoa -Dmpath=$mpath -Dsdl=$sdl -Dsdl_image=$sdl_image \
         -Dvnc=$vnc -Dvnc_sasl=$vnc_sasl -Dvnc_jpeg=$vnc_jpeg -Dvnc_png=$vnc_png \
-        -Dgettext=$gettext -Dxkbcommon=$xkbcommon -Du2f=$u2f \
+        -Dgettext=$gettext -Dxkbcommon=$xkbcommon -Du2f=$u2f -Dvirtiofsd=$virtiofsd \
         -Dcapstone=$capstone -Dslirp=$slirp -Dfdt=$fdt \
         -Diconv=$iconv -Dcurses=$curses -Dlibudev=$libudev\
         -Ddocs=$docs -Dsphinx_build=$sphinx_build -Dinstall_blobs=$blobs \

docs/tools/virtiofsd.rst

@@ -17,13 +17,24 @@ 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.  Upon startup the program will
-switch into a new file system namespace with the shared directory tree as its
-root.  This prevents "file system escapes" due to symlinks and other file
-system objects that might lead to files outside the shared directory.  The
-program also sandboxes itself using seccomp(2) to prevent ptrace(2) and other
-vectors that could allow an attacker to compromise the system after gaining
-control of the virtiofsd process.
+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
 -------
@@ -69,6 +80,13 @@ Options
   * 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.
 
@@ -109,6 +127,167 @@ Options
   timeout.  ``always`` sets a long cache lifetime at the expense of coherency.
   The default is ``auto``.
 
+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.
+
+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 explict 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 'securty.' 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.
+
+xattr-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.
+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.
+
 Examples
 --------
 

include/standard-headers/linux/fuse.h

@@ -227,7 +227,7 @@ struct fuse_attr {
 	uint32_t	gid;
 	uint32_t	rdev;
 	uint32_t	blksize;
-	uint32_t	padding;
+	uint32_t	flags;
 };
 
 struct fuse_kstatfs {
@@ -310,6 +310,7 @@ struct fuse_file_lock {
  * FUSE_NO_OPENDIR_SUPPORT: kernel supports zero-message opendir
  * FUSE_EXPLICIT_INVAL_DATA: only invalidate cached pages on explicit request
  * FUSE_MAP_ALIGNMENT: map_alignment field is valid
+ * FUSE_ATTR_FLAGS: fuse_attr.flags is present and valid
  */
 #define FUSE_ASYNC_READ		(1 << 0)
 #define FUSE_POSIX_LOCKS	(1 << 1)
@@ -338,6 +339,7 @@ struct fuse_file_lock {
 #define FUSE_NO_OPENDIR_SUPPORT (1 << 24)
 #define FUSE_EXPLICIT_INVAL_DATA (1 << 25)
 #define FUSE_MAP_ALIGNMENT	(1 << 26)
+#define FUSE_ATTR_FLAGS		(1 << 27)
 
 /**
  * CUSE INIT request/reply flags
@@ -413,6 +415,13 @@ struct fuse_file_lock {
  */
 #define FUSE_FSYNC_FDATASYNC	(1 << 0)
 
+/**
+ * fuse_attr flags
+ *
+ * FUSE_ATTR_SUBMOUNT: File/directory is a submount point
+ */
+#define FUSE_ATTR_SUBMOUNT      (1 << 0)
+
 enum fuse_opcode {
 	FUSE_LOOKUP		= 1,
 	FUSE_FORGET		= 2,  /* no reply */

meson.build

@@ -2045,6 +2045,7 @@ summary_info += {'Audio drivers':     config_host['CONFIG_AUDIO_DRIVERS']}
 summary_info += {'Block whitelist (rw)': config_host['CONFIG_BDRV_RW_WHITELIST']}
 summary_info += {'Block whitelist (ro)': config_host['CONFIG_BDRV_RO_WHITELIST']}
 summary_info += {'VirtFS support':    config_host.has_key('CONFIG_VIRTFS')}
+summary_info += {'build virtiofs daemon': have_virtiofsd}
 summary_info += {'Multipath support': mpathpersist.found()}
 summary_info += {'VNC support':       vnc.found()}
 if vnc.found()

meson_options.txt

@@ -62,6 +62,8 @@ option('vnc_sasl', type : 'feature', value : 'auto',
        description: 'SASL authentication for VNC server')
 option('xkbcommon', type : 'feature', value : 'auto',
        description: 'xkbcommon support')
+option('virtiofsd', type: 'feature', value: 'auto',
+       description: 'build virtiofs daemon (virtiofsd)')
 
 option('capstone', type: 'combo', value: 'auto',
        choices: ['disabled', 'enabled', 'auto', 'system', 'internal'],

tests/acceptance/boot_linux.py

@@ -57,7 +57,7 @@ def download_boot(self):
             self.cancel('Failed to download/prepare boot image')
         return boot.path
 
-    def download_cloudinit(self):
+    def download_cloudinit(self, ssh_pubkey=None):
         self.log.info('Preparing cloudinit image')
         try:
             cloudinit_iso = os.path.join(self.workdir, 'cloudinit.iso')
@@ -67,7 +67,8 @@ def download_cloudinit(self):
                           password='password',
                           # QEMU's hard coded usermode router address
                           phone_home_host='10.0.2.2',
-                          phone_home_port=self.phone_home_port)
+                          phone_home_port=self.phone_home_port,
+                          authorized_key=ssh_pubkey)
         except Exception:
             self.cancel('Failed to prepared cloudinit image')
         return cloudinit_iso
@@ -80,19 +81,19 @@ class BootLinux(BootLinuxBase):
     timeout = 900
     chksum = None
 
-    def setUp(self):
+    def setUp(self, ssh_pubkey=None):
         super(BootLinux, self).setUp()
         self.vm.add_args('-smp', '2')
         self.vm.add_args('-m', '1024')
         self.prepare_boot()
-        self.prepare_cloudinit()
+        self.prepare_cloudinit(ssh_pubkey)
 
     def prepare_boot(self):
         path = self.download_boot()
         self.vm.add_args('-drive', 'file=%s' % path)
 
-    def prepare_cloudinit(self):
-        cloudinit_iso = self.download_cloudinit()
+    def prepare_cloudinit(self, ssh_pubkey=None):
+        cloudinit_iso = self.download_cloudinit(ssh_pubkey)
         self.vm.add_args('-drive', 'file=%s,format=raw' % cloudinit_iso)
 
     def launch_and_wait(self):