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-rw-r--r--pkg/sentry/fsimpl/gofer/directory.go12
-rw-r--r--pkg/sentry/fsimpl/gofer/filesystem.go77
2 files changed, 52 insertions, 37 deletions
diff --git a/pkg/sentry/fsimpl/gofer/directory.go b/pkg/sentry/fsimpl/gofer/directory.go
index 2a8011eb4..40dce553e 100644
--- a/pkg/sentry/fsimpl/gofer/directory.go
+++ b/pkg/sentry/fsimpl/gofer/directory.go
@@ -82,7 +82,7 @@ type createSyntheticOpts struct {
// Preconditions: d.dirMu must be locked. d.isDir(). d does not already contain
// a child with the given name.
func (d *dentry) createSyntheticChildLocked(opts *createSyntheticOpts) {
- d2 := &dentry{
+ child := &dentry{
refs: 1, // held by d
fs: d.fs,
ino: d.fs.nextSyntheticIno(),
@@ -97,16 +97,16 @@ func (d *dentry) createSyntheticChildLocked(opts *createSyntheticOpts) {
case linux.S_IFDIR:
// Nothing else needs to be done.
case linux.S_IFSOCK:
- d2.endpoint = opts.endpoint
+ child.endpoint = opts.endpoint
case linux.S_IFIFO:
- d2.pipe = opts.pipe
+ child.pipe = opts.pipe
default:
panic(fmt.Sprintf("failed to create synthetic file of unrecognized type: %v", opts.mode.FileType()))
}
- d2.pf.dentry = d2
- d2.vfsd.Init(d2)
+ child.pf.dentry = child
+ child.vfsd.Init(child)
- d.cacheNewChildLocked(d2, opts.name)
+ d.cacheNewChildLocked(child, opts.name)
d.syntheticChildren++
}
diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go
index 9a90351e5..1b6fa4e14 100644
--- a/pkg/sentry/fsimpl/gofer/filesystem.go
+++ b/pkg/sentry/fsimpl/gofer/filesystem.go
@@ -330,7 +330,7 @@ func (fs *filesystem) resolveLocked(ctx context.Context, rp *vfs.ResolvingPath,
//
// Preconditions: !rp.Done(). For the final path component in rp,
// !rp.ShouldFollowSymlink().
-func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir bool, createInRemoteDir func(parent *dentry, name string) error, createInSyntheticDir func(parent *dentry, name string) error) error {
+func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir bool, createInRemoteDir func(parent *dentry, name string, ds **[]*dentry) error, createInSyntheticDir func(parent *dentry, name string) error) error {
var ds *[]*dentry
fs.renameMu.RLock()
defer fs.renameMuRUnlockAndCheckCaching(ctx, &ds)
@@ -399,7 +399,7 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir
// RPC will fail with EEXIST like we would have. If the RPC succeeds, and a
// stale dentry exists, the dentry will fail revalidation next time it's
// used.
- if err := createInRemoteDir(parent, name); err != nil {
+ if err := createInRemoteDir(parent, name, &ds); err != nil {
return err
}
ev := linux.IN_CREATE
@@ -414,7 +414,7 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir
}
// No cached dentry exists; however, there might still be an existing file
// at name. As above, we attempt the file creation RPC anyway.
- if err := createInRemoteDir(parent, name); err != nil {
+ if err := createInRemoteDir(parent, name, &ds); err != nil {
return err
}
if child, ok := parent.children[name]; ok && child == nil {
@@ -721,7 +721,7 @@ func (fs *filesystem) GetParentDentryAt(ctx context.Context, rp *vfs.ResolvingPa
// LinkAt implements vfs.FilesystemImpl.LinkAt.
func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.VirtualDentry) error {
- return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, childName string) error {
+ return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, childName string, _ **[]*dentry) error {
if rp.Mount() != vd.Mount() {
return syserror.EXDEV
}
@@ -754,7 +754,7 @@ func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.
// MkdirAt implements vfs.FilesystemImpl.MkdirAt.
func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MkdirOptions) error {
creds := rp.Credentials()
- return fs.doCreateAt(ctx, rp, true /* dir */, func(parent *dentry, name string) error {
+ return fs.doCreateAt(ctx, rp, true /* dir */, func(parent *dentry, name string, _ **[]*dentry) error {
if _, err := parent.file.mkdir(ctx, name, (p9.FileMode)(opts.Mode), (p9.UID)(creds.EffectiveKUID), (p9.GID)(creds.EffectiveKGID)); err != nil {
if !opts.ForSyntheticMountpoint || err == syserror.EEXIST {
return err
@@ -789,34 +789,49 @@ func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts v
// MknodAt implements vfs.FilesystemImpl.MknodAt.
func (fs *filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MknodOptions) error {
- return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, name string) error {
+ return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, name string, ds **[]*dentry) error {
creds := rp.Credentials()
_, err := parent.file.mknod(ctx, name, (p9.FileMode)(opts.Mode), opts.DevMajor, opts.DevMinor, (p9.UID)(creds.EffectiveKUID), (p9.GID)(creds.EffectiveKGID))
- // If the gofer does not allow creating a socket or pipe, create a
- // synthetic one, i.e. one that is kept entirely in memory.
- if err == syserror.EPERM {
- switch opts.Mode.FileType() {
- case linux.S_IFSOCK:
- parent.createSyntheticChildLocked(&createSyntheticOpts{
- name: name,
- mode: opts.Mode,
- kuid: creds.EffectiveKUID,
- kgid: creds.EffectiveKGID,
- endpoint: opts.Endpoint,
- })
- return nil
- case linux.S_IFIFO:
- parent.createSyntheticChildLocked(&createSyntheticOpts{
- name: name,
- mode: opts.Mode,
- kuid: creds.EffectiveKUID,
- kgid: creds.EffectiveKGID,
- pipe: pipe.NewVFSPipe(true /* isNamed */, pipe.DefaultPipeSize, usermem.PageSize),
- })
- return nil
- }
+ if err != syserror.EPERM {
+ return err
}
- return err
+
+ // EPERM means that gofer does not allow creating a socket or pipe. Fallback
+ // to creating a synthetic one, i.e. one that is kept entirely in memory.
+
+ // Check that we're not overriding an existing file with a synthetic one.
+ _, err = fs.stepLocked(ctx, rp, parent, true, ds)
+ switch {
+ case err == nil:
+ // Step succeeded, another file exists.
+ return syserror.EEXIST
+ case err != syserror.ENOENT:
+ // Unexpected error.
+ return err
+ }
+
+ switch opts.Mode.FileType() {
+ case linux.S_IFSOCK:
+ parent.createSyntheticChildLocked(&createSyntheticOpts{
+ name: name,
+ mode: opts.Mode,
+ kuid: creds.EffectiveKUID,
+ kgid: creds.EffectiveKGID,
+ endpoint: opts.Endpoint,
+ })
+ return nil
+ case linux.S_IFIFO:
+ parent.createSyntheticChildLocked(&createSyntheticOpts{
+ name: name,
+ mode: opts.Mode,
+ kuid: creds.EffectiveKUID,
+ kgid: creds.EffectiveKGID,
+ pipe: pipe.NewVFSPipe(true /* isNamed */, pipe.DefaultPipeSize, usermem.PageSize),
+ })
+ return nil
+ }
+ // Retain error from gofer if synthetic file cannot be created internally.
+ return syserror.EPERM
}, nil)
}
@@ -1452,7 +1467,7 @@ func (fs *filesystem) StatFSAt(ctx context.Context, rp *vfs.ResolvingPath) (linu
// SymlinkAt implements vfs.FilesystemImpl.SymlinkAt.
func (fs *filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, target string) error {
- return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, name string) error {
+ return fs.doCreateAt(ctx, rp, false /* dir */, func(parent *dentry, name string, _ **[]*dentry) error {
creds := rp.Credentials()
_, err := parent.file.symlink(ctx, target, name, (p9.UID)(creds.EffectiveKUID), (p9.GID)(creds.EffectiveKGID))
return err
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-06 15:26:28 +0000