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-rw-r--r--pkg/sentry/vfs/mount.go56
-rw-r--r--pkg/sentry/vfs/vfs.go4
-rw-r--r--pkg/sentry/vfs/vfs_state_autogen.go2
3 files changed, 47 insertions, 15 deletions
diff --git a/pkg/sentry/vfs/mount.go b/pkg/sentry/vfs/mount.go
index 02850b65c..e4ac6524b 100644
--- a/pkg/sentry/vfs/mount.go
+++ b/pkg/sentry/vfs/mount.go
@@ -28,9 +28,6 @@ import (
"gvisor.dev/gvisor/pkg/syserror"
)
-// lastMountID is used to allocate mount ids. Must be accessed atomically.
-var lastMountID uint64
-
// A Mount is a replacement of a Dentry (Mount.key.point) from one Filesystem
// (Mount.key.parent.fs) with a Dentry (Mount.root) from another Filesystem
// (Mount.fs), which applies to path resolution in the context of a particular
@@ -97,7 +94,7 @@ type Mount struct {
func newMount(vfs *VirtualFilesystem, fs *Filesystem, root *Dentry, mntns *MountNamespace, opts *MountOptions) *Mount {
mnt := &Mount{
- ID: atomic.AddUint64(&lastMountID, 1),
+ ID: atomic.AddUint64(&vfs.lastMountID, 1),
vfs: vfs,
fs: fs,
root: root,
@@ -111,6 +108,16 @@ func newMount(vfs *VirtualFilesystem, fs *Filesystem, root *Dentry, mntns *Mount
return mnt
}
+// Options returns a copy of the MountOptions currently applicable to mnt.
+func (mnt *Mount) Options() MountOptions {
+ mnt.vfs.mountMu.Lock()
+ defer mnt.vfs.mountMu.Unlock()
+ return MountOptions{
+ Flags: mnt.flags,
+ ReadOnly: mnt.readOnly(),
+ }
+}
+
// A MountNamespace is a collection of Mounts.
//
// MountNamespaces are reference-counted. Unless otherwise specified, all
@@ -148,7 +155,7 @@ type MountNamespace struct {
func (vfs *VirtualFilesystem) NewMountNamespace(ctx context.Context, creds *auth.Credentials, source, fsTypeName string, opts *GetFilesystemOptions) (*MountNamespace, error) {
rft := vfs.getFilesystemType(fsTypeName)
if rft == nil {
- ctx.Warningf("Unknown filesystem: %s", fsTypeName)
+ ctx.Warningf("Unknown filesystem type: %s", fsTypeName)
return nil, syserror.ENODEV
}
fs, root, err := rft.fsType.GetFilesystem(ctx, vfs, creds, source, *opts)
@@ -175,26 +182,34 @@ func (vfs *VirtualFilesystem) NewDisconnectedMount(fs *Filesystem, root *Dentry,
return newMount(vfs, fs, root, nil /* mntns */, opts), nil
}
-// MountAt creates and mounts a Filesystem configured by the given arguments.
-func (vfs *VirtualFilesystem) MountAt(ctx context.Context, creds *auth.Credentials, source string, target *PathOperation, fsTypeName string, opts *MountOptions) error {
+// MountDisconnected creates a Filesystem configured by the given arguments,
+// then returns a Mount representing it. The new Mount is not associated with
+// any MountNamespace and is not connected to any other Mounts.
+func (vfs *VirtualFilesystem) MountDisconnected(ctx context.Context, creds *auth.Credentials, source string, fsTypeName string, opts *MountOptions) (*Mount, error) {
rft := vfs.getFilesystemType(fsTypeName)
if rft == nil {
- return syserror.ENODEV
+ return nil, syserror.ENODEV
}
if !opts.InternalMount && !rft.opts.AllowUserMount {
- return syserror.ENODEV
+ return nil, syserror.ENODEV
}
fs, root, err := rft.fsType.GetFilesystem(ctx, vfs, creds, source, opts.GetFilesystemOptions)
if err != nil {
- return err
+ return nil, err
}
+ defer root.DecRef()
+ defer fs.DecRef()
+ return vfs.NewDisconnectedMount(fs, root, opts)
+}
+// ConnectMountAt connects mnt at the path represented by target.
+//
+// Preconditions: mnt must be disconnected.
+func (vfs *VirtualFilesystem) ConnectMountAt(ctx context.Context, creds *auth.Credentials, mnt *Mount, target *PathOperation) error {
// We can't hold vfs.mountMu while calling FilesystemImpl methods due to
// lock ordering.
vd, err := vfs.GetDentryAt(ctx, creds, target, &GetDentryOptions{})
if err != nil {
- root.DecRef()
- fs.DecRef()
return err
}
vfs.mountMu.Lock()
@@ -204,8 +219,6 @@ func (vfs *VirtualFilesystem) MountAt(ctx context.Context, creds *auth.Credentia
vd.dentry.mu.Unlock()
vfs.mountMu.Unlock()
vd.DecRef()
- root.DecRef()
- fs.DecRef()
return syserror.ENOENT
}
// vd might have been mounted over between vfs.GetDentryAt() and
@@ -238,7 +251,6 @@ func (vfs *VirtualFilesystem) MountAt(ctx context.Context, creds *auth.Credentia
// point and the mount root are directories, or neither are, and returns
// ENOTDIR if this is not the case.
mntns := vd.mount.ns
- mnt := newMount(vfs, fs, root, mntns, opts)
vfs.mounts.seq.BeginWrite()
vfs.connectLocked(mnt, vd, mntns)
vfs.mounts.seq.EndWrite()
@@ -247,6 +259,19 @@ func (vfs *VirtualFilesystem) MountAt(ctx context.Context, creds *auth.Credentia
return nil
}
+// MountAt creates and mounts a Filesystem configured by the given arguments.
+func (vfs *VirtualFilesystem) MountAt(ctx context.Context, creds *auth.Credentials, source string, target *PathOperation, fsTypeName string, opts *MountOptions) error {
+ mnt, err := vfs.MountDisconnected(ctx, creds, source, fsTypeName, opts)
+ if err != nil {
+ return err
+ }
+ if err := vfs.ConnectMountAt(ctx, creds, mnt, target); err != nil {
+ mnt.DecRef()
+ return err
+ }
+ return nil
+}
+
// UmountAt removes the Mount at the given path.
func (vfs *VirtualFilesystem) UmountAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *UmountOptions) error {
if opts.Flags&^(linux.MNT_FORCE|linux.MNT_DETACH) != 0 {
@@ -377,6 +402,7 @@ func (vfs *VirtualFilesystem) connectLocked(mnt *Mount, vd VirtualDentry, mntns
}
vd.mount.children[mnt] = struct{}{}
atomic.AddUint32(&vd.dentry.mounts, 1)
+ mnt.ns = mntns
mntns.mountpoints[vd.dentry]++
vfs.mounts.insertSeqed(mnt)
vfsmpmounts, ok := vfs.mountpoints[vd.dentry]
diff --git a/pkg/sentry/vfs/vfs.go b/pkg/sentry/vfs/vfs.go
index 8d7f8f8af..6d2ba53ea 100644
--- a/pkg/sentry/vfs/vfs.go
+++ b/pkg/sentry/vfs/vfs.go
@@ -82,6 +82,10 @@ type VirtualFilesystem struct {
// mountpoints is analogous to Linux's mountpoint_hashtable.
mountpoints map[*Dentry]map[*Mount]struct{}
+ // lastMountID is the last allocated mount ID. lastMountID is accessed
+ // using atomic memory operations.
+ lastMountID uint64
+
// anonMount is a Mount, not included in mounts or mountpoints,
// representing an anonFilesystem. anonMount is used to back
// VirtualDentries returned by VirtualFilesystem.NewAnonVirtualDentry().
diff --git a/pkg/sentry/vfs/vfs_state_autogen.go b/pkg/sentry/vfs/vfs_state_autogen.go
index 0cf6ed48d..b21238d3f 100644
--- a/pkg/sentry/vfs/vfs_state_autogen.go
+++ b/pkg/sentry/vfs/vfs_state_autogen.go
@@ -152,6 +152,7 @@ func (x *VirtualFilesystem) save(m state.Map) {
x.beforeSave()
m.Save("mounts", &x.mounts)
m.Save("mountpoints", &x.mountpoints)
+ m.Save("lastMountID", &x.lastMountID)
m.Save("anonMount", &x.anonMount)
m.Save("devices", &x.devices)
m.Save("anonBlockDevMinorNext", &x.anonBlockDevMinorNext)
@@ -164,6 +165,7 @@ func (x *VirtualFilesystem) afterLoad() {}
func (x *VirtualFilesystem) load(m state.Map) {
m.Load("mounts", &x.mounts)
m.Load("mountpoints", &x.mountpoints)
+ m.Load("lastMountID", &x.lastMountID)
m.Load("anonMount", &x.anonMount)
m.Load("devices", &x.devices)
m.Load("anonBlockDevMinorNext", &x.anonBlockDevMinorNext)
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-16 23:40:36 +0000