Merge pull request #315 from cdburkard/patches/fix_bindpy

Added support for mount namespaces in bind.py

examples/bind.py

@@ -1,197 +1,72 @@
 #!/usr/bin/python
 
 """
-bind.py: Bind mount prototype
+bind.py: Bind mount example
 
-This creates hosts with private directories as desired.
+This creates hosts with private directories that the user specifies.
+These hosts may have persistent directories that will be available
+across multiple mininet session, or temporary directories that will
+only last for one mininet session. To specify a persistent
+directory, add a tuple to a list of private directories:
+
+    [ ( 'directory to be mounted on', 'directory to be mounted' ) ]
+
+String expansion may be used to create a directory template for
+each host. To do this, add a %(name)s in place of the host name
+when creating your list of directories:
+
+    [ ( '/var/run', '/tmp/%(name)s/var/run' ) ]
+
+If no persistent directory is specified, the directories will default
+to temporary private directories. To do this, simply create a list of
+directories to be made private. A tmpfs will then be mounted on them.
+
+You may use both temporary and persistent directories at the same
+time. In the following privateDirs string, each host will have a 
+persistent directory in the root filesystem at
+"/tmp/(hostname)/var/run" mounted on "/var/run". Each host will also
+have a temporary private directory mounted on "/var/log".
+
+    [ ( '/var/run', '/tmp/%(name)s/var/run' ), '/var/log' ]
+
+This example has both persistent directories mounted on '/var/log'
+and '/var/run'. It also has a temporary private directory mounted
+on '/var/mn'
 """
 
 from mininet.net import Mininet
-from mininet.node import Host
+from mininet.node import Host, HostWithPrivateDirs
 from mininet.cli import CLI
-from mininet.util import errFail, quietRun, errRun
 from mininet.topo import SingleSwitchTopo
 from mininet.log import setLogLevel, info, debug
 
-from os.path import realpath
 from functools import partial
 
 
-# Utility functions for unmounting a tree
-
-MNRUNDIR = realpath( '/var/run/mn' )
-
-def mountPoints():
-    "Return list of mounted file systems"
-    mtab, _err, _ret = errFail( 'cat /proc/mounts' )
-    lines = mtab.split( '\n' )
-    mounts = []
-    for line in lines:
-        if not line:
-            continue
-        fields = line.split( ' ')
-        mount = fields[ 1 ]
-        mounts.append( mount )
-    return mounts
-
-def unmountAll( rootdir=MNRUNDIR ):
-    "Unmount all mounts under a directory tree"
-    rootdir = realpath( rootdir )
-    # Find all mounts below rootdir
-    # This is subtle because /foo is not
-    # a parent of /foot
-    dirslash = rootdir + '/'
-    mounts = [ m for m in mountPoints()
-              if m == dir or m.find( dirslash ) == 0 ]
-    # Unmount them from bottom to top
-    mounts.sort( reverse=True )
-    for mount in mounts:
-        debug( 'Unmounting', mount, '\n' )
-        _out, err, code = errRun( 'umount', mount )
-        if code != 0:
-            info( '*** Warning: failed to umount', mount, '\n' )
-            info( err )
-
-
-class HostWithPrivateDirs( Host ):
-    "Host with private directories"
-
-    mnRunDir = MNRUNDIR
-
-    def __init__(self, name, *args, **kwargs ):
-        """privateDirs: list of private directories
-           remounts: dirs to remount
-           unmount: unmount dirs in cleanup? (True)
-           Note: if unmount is False, you must call unmountAll()
-           manually."""
-        self.privateDirs = kwargs.pop( 'privateDirs', [] )
-        self.remounts = kwargs.pop( 'remounts', [] )
-        self.unmount = kwargs.pop( 'unmount', True )
-        Host.__init__( self, name, *args, **kwargs )
-        self.rundir = '%s/%s' % ( self.mnRunDir, name )
-        self.root, self.private = None, None  # set in createBindMounts
-        if self.privateDirs:
-            self.privateDirs = [ realpath( d ) for d in self.privateDirs ]
-            self.createBindMounts()
-        # These should run in the namespace before we chroot,
-        # in order to put the right entries in /etc/mtab
-        # Eventually this will allow a local pid space
-        # Now we chroot and cd to wherever we were before.
-        pwd = self.cmd( 'pwd' ).strip()
-        self.sendCmd( 'exec chroot', self.root, 'bash -ms mininet:'
-                       + self.name )
-        self.waiting = False
-        self.cmd( 'cd', pwd )
-        # In order for many utilities to work,
-        # we need to remount /proc and /sys
-        self.cmd( 'mount /proc' )
-        self.cmd( 'mount /sys' )
-
-    def mountPrivateDirs( self ):
-        "Create and bind mount private dirs"
-        for dir_ in self.privateDirs:
-            privateDir = self.private + dir_
-            errFail( 'mkdir -p ' + privateDir )
-            mountPoint = self.root + dir_
-            errFail( 'mount -B %s %s' %
-                           ( privateDir, mountPoint) )
-
-    def mountDirs( self, dirs ):
-        "Mount a list of directories"
-        for dir_ in dirs:
-            mountpoint = self.root + dir_
-            errFail( 'mount -B %s %s' %
-                     ( dir_, mountpoint ) )
-
-    @classmethod
-    def findRemounts( cls, fstypes=None ):
-        """Identify mount points in /proc/mounts to remount
-           fstypes: file system types to match"""
-        if fstypes is None:
-            fstypes = [ 'nfs' ]
-        dirs = quietRun( 'cat /proc/mounts' ).strip().split( '\n' )
-        remounts = []
-        for dir_ in dirs:
-            line = dir_.split()
-            mountpoint, fstype = line[ 1 ], line[ 2 ]
-            # Don't re-remount directories!!!
-            if mountpoint.find( cls.mnRunDir ) == 0:
-                continue
-            if fstype in fstypes:
-                remounts.append( mountpoint )
-        return remounts
-
-    def createBindMounts( self ):
-        """Create a chroot directory structure,
-           with self.privateDirs as private dirs"""
-        errFail( 'mkdir -p '+ self.rundir )
-        unmountAll( self.rundir )
-        # Create /root and /private directories
-        self.root = self.rundir + '/root'
-        self.private = self.rundir + '/private'
-        errFail( 'mkdir -p ' + self.root )
-        errFail( 'mkdir -p ' + self.private )
-        # Recursively mount / in private doort
-        # note we'll remount /sys and /proc later
-        errFail( 'mount -B / ' + self.root )
-        self.mountDirs( self.remounts )
-        self.mountPrivateDirs()
-
-    def unmountBindMounts( self ):
-        "Unmount all of our bind mounts"
-        unmountAll( self.rundir )
-
-    def popen( self, *args, **kwargs ):
-        "Popen with chroot support"
-        chroot = kwargs.pop( 'chroot', True )
-        mncmd = kwargs.get( 'mncmd',
-                           [ 'mnexec', '-a', str( self.pid ) ] )
-        if chroot:
-            mncmd = [ 'chroot', self.root ] + mncmd
-            kwargs[ 'mncmd' ] = mncmd
-        return Host.popen( self, *args, **kwargs )
-
-    def cleanup( self ):
-        """Clean up, then unmount bind mounts
-           unmount: actually unmount bind mounts?"""
-        # Wait for process to actually terminate
-        self.shell.wait()
-        Host.cleanup( self )
-        if self.unmount:
-            self.unmountBindMounts()
-            errFail( 'rmdir ' + self.root )
-
-
-# Convenience aliases
-
-findRemounts = HostWithPrivateDirs.findRemounts
-
-
 # Sample usage
 
 def testHostWithPrivateDirs():
     "Test bind mounts"
     topo = SingleSwitchTopo( 10 )
-    remounts = findRemounts( fstypes=[ 'nfs' ] )
+    privateDirs = [ ( '/var/log', '/tmp/%(name)s/var/log' ), 
-    privateDirs = [ '/var/log', '/var/run' ]
+                    ( '/var/run', '/tmp/%(name)s/var/run' ), 
-    host = partial( HostWithPrivateDirs, remounts=remounts,
+                      '/var/mn' ]
-                    privateDirs=privateDirs, unmount=False )
+    host = partial( HostWithPrivateDirs,
+                    privateDirs=privateDirs )
     net = Mininet( topo=topo, host=host )
     net.start()
-    info( 'Private Directories:', privateDirs, '\n' )
+    directories = []
+    for directory in privateDirs:
+        directories.append( directory[ 0 ]
+                            if isinstance( directory, tuple )
+                            else directory )
+    info( 'Private Directories:',  directories, '\n' )
     CLI( net )
     net.stop()
-    # We do this all at once to save a bit of time
-    info( 'Unmounting host bind mounts...\n' )
-    unmountAll()
-
 
 if __name__ == '__main__':
-    unmountAll()
     setLogLevel( 'info' )
     testHostWithPrivateDirs()
     info( 'Done.\n')
 
 
-
-

mininet/node.py

@@ -16,6 +16,11 @@ Host: a virtual host. By default, a host is simply a shell; commands
 CPULimitedHost: a virtual host whose CPU bandwidth is limited by
     RT or CFS bandwidth limiting.
 
+HostWithPrivateDirs: a virtual host that has user-specified private
+    directories. These may be temporary directories stored as a tmpfs,
+    or persistent directories that are mounted from another directory in
+    the root filesystem.
+
 Switch: superclass for switch nodes.
 
 UserSwitch: a switch using the user-space switch from the OpenFlow
@@ -725,6 +730,33 @@ class CPULimitedHost( Host ):
         mountCgroups()
         cls.inited = True
 
+class HostWithPrivateDirs( Host ):
+    "Host with private directories"
+
+    def __init__( self, name, *args, **kwargs ):
+        "privateDirs: list of private directory strings or tuples"
+        self.name = name
+        self.privateDirs = kwargs.pop( 'privateDirs', [] )
+        Host.__init__( self, name, *args, **kwargs )
+        self.mountPrivateDirs()
+
+    def mountPrivateDirs( self ):
+        "mount private directories"
+        for directory in self.privateDirs:
+            if isinstance( directory, tuple ):
+                # mount given private directory
+                privateDir = directory[ 1 ] % self.__dict__ 
+                mountPoint = directory[ 0 ]
+                self.cmd( 'mkdir -p %s' % privateDir )
+                self.cmd( 'mkdir -p %s' % mountPoint )
+                self.cmd( 'mount --bind %s %s' %
+                               ( privateDir, mountPoint ) )
+            else:
+                # mount temporary filesystem on directory
+                self.cmd( 'mkdir -p %s' % directory ) 
+                self.cmd( 'mount -n -t tmpfs tmpfs %s' % directory )
+
+
 
 # Some important things to note:
 #

mnexec.c

@@ -140,7 +140,7 @@ int main(int argc, char *argv[])
             fflush(stdout);
             break;
         case 'a':
-            /* Attach to pid's network namespace */
+            /* Attach to pid's network namespace and mount namespace*/
             pid = atoi(optarg);
             sprintf(path, "/proc/%d/ns/net", pid );
             nsid = open(path, O_RDONLY);
@@ -152,6 +152,16 @@ int main(int argc, char *argv[])
                 perror("setns");
                 return 1;
             }
+            sprintf(path, "/proc/%d/ns/mnt", pid );
+            nsid = open(path, O_RDONLY);
+            if (nsid < 0) {
+                perror(path);
+                return 1;
+            }
+            if (setns(nsid, 0) != 0) {
+                perror("setns");
+                return 1;
+            }
             break;
         case 'g':
             /* Attach to cgroup */