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-rw-r--r--pkg/sentry/fsimpl/kernfs/fd_impl_util.go46
-rw-r--r--pkg/sentry/fsimpl/kernfs/inode_impl_util.go12
-rw-r--r--pkg/sentry/fsimpl/kernfs/kernfs_test.go8
3 files changed, 50 insertions, 16 deletions
diff --git a/pkg/sentry/fsimpl/kernfs/fd_impl_util.go b/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
index fcee6200a..6518ff5cd 100644
--- a/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
@@ -15,7 +15,7 @@
package kernfs
import (
- "math"
+ "fmt"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
@@ -28,9 +28,25 @@ import (
"gvisor.dev/gvisor/pkg/usermem"
)
+// SeekEndConfig describes the SEEK_END behaviour for FDs.
+type SeekEndConfig int
+
+// Constants related to SEEK_END behaviour for FDs.
+const (
+ // Consider the end of the file to be after the final static entry. This is
+ // the default option.
+ SeekEndStaticEntries = iota
+ // Consider the end of the file to be at offset 0.
+ SeekEndZero
+)
+
+// GenericDirectoryFDOptions contains configuration for a GenericDirectoryFD.
+type GenericDirectoryFDOptions struct {
+ SeekEnd SeekEndConfig
+}
+
// GenericDirectoryFD implements vfs.FileDescriptionImpl for a generic directory
-// inode that uses OrderChildren to track child nodes. GenericDirectoryFD is not
-// compatible with dynamic directories.
+// inode that uses OrderChildren to track child nodes.
//
// Note that GenericDirectoryFD holds a lock over OrderedChildren while calling
// IterDirents callback. The IterDirents callback therefore cannot hash or
@@ -45,6 +61,9 @@ type GenericDirectoryFD struct {
vfs.DirectoryFileDescriptionDefaultImpl
vfs.LockFD
+ // Immutable.
+ seekEnd SeekEndConfig
+
vfsfd vfs.FileDescription
children *OrderedChildren
@@ -57,9 +76,9 @@ type GenericDirectoryFD struct {
// NewGenericDirectoryFD creates a new GenericDirectoryFD and returns its
// dentry.
-func NewGenericDirectoryFD(m *vfs.Mount, d *vfs.Dentry, children *OrderedChildren, locks *vfs.FileLocks, opts *vfs.OpenOptions) (*GenericDirectoryFD, error) {
+func NewGenericDirectoryFD(m *vfs.Mount, d *vfs.Dentry, children *OrderedChildren, locks *vfs.FileLocks, opts *vfs.OpenOptions, fdOpts GenericDirectoryFDOptions) (*GenericDirectoryFD, error) {
fd := &GenericDirectoryFD{}
- if err := fd.Init(children, locks, opts); err != nil {
+ if err := fd.Init(children, locks, opts, fdOpts); err != nil {
return nil, err
}
if err := fd.vfsfd.Init(fd, opts.Flags, m, d, &vfs.FileDescriptionOptions{}); err != nil {
@@ -71,12 +90,13 @@ func NewGenericDirectoryFD(m *vfs.Mount, d *vfs.Dentry, children *OrderedChildre
// Init initializes a GenericDirectoryFD. Use it when overriding
// GenericDirectoryFD. Caller must call fd.VFSFileDescription.Init() with the
// correct implementation.
-func (fd *GenericDirectoryFD) Init(children *OrderedChildren, locks *vfs.FileLocks, opts *vfs.OpenOptions) error {
+func (fd *GenericDirectoryFD) Init(children *OrderedChildren, locks *vfs.FileLocks, opts *vfs.OpenOptions, fdOpts GenericDirectoryFDOptions) error {
if vfs.AccessTypesForOpenFlags(opts)&vfs.MayWrite != 0 {
// Can't open directories for writing.
return syserror.EISDIR
}
fd.LockFD.Init(locks)
+ fd.seekEnd = fdOpts.SeekEnd
fd.children = children
return nil
}
@@ -209,9 +229,17 @@ func (fd *GenericDirectoryFD) Seek(ctx context.Context, offset int64, whence int
case linux.SEEK_CUR:
offset += fd.off
case linux.SEEK_END:
- // TODO(gvisor.dev/issue/1193): This can prevent new files from showing up
- // if they are added after SEEK_END.
- offset = math.MaxInt64
+ switch fd.seekEnd {
+ case SeekEndStaticEntries:
+ fd.children.mu.RLock()
+ offset += int64(len(fd.children.set))
+ offset += 2 // '.' and '..' aren't tracked in children.
+ fd.children.mu.RUnlock()
+ case SeekEndZero:
+ // No-op: offset += 0.
+ default:
+ panic(fmt.Sprintf("Invalid GenericDirectoryFD.seekEnd = %v", fd.seekEnd))
+ }
default:
return 0, syserror.EINVAL
}
diff --git a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
index fe8a1e710..885856868 100644
--- a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
@@ -555,15 +555,16 @@ type StaticDirectory struct {
InodeNoDynamicLookup
OrderedChildren
- locks vfs.FileLocks
+ locks vfs.FileLocks
+ fdOpts GenericDirectoryFDOptions
}
var _ Inode = (*StaticDirectory)(nil)
// NewStaticDir creates a new static directory and returns its dentry.
-func NewStaticDir(creds *auth.Credentials, devMajor, devMinor uint32, ino uint64, perm linux.FileMode, children map[string]*Dentry) *Dentry {
+func NewStaticDir(creds *auth.Credentials, devMajor, devMinor uint32, ino uint64, perm linux.FileMode, children map[string]*Dentry, fdOpts GenericDirectoryFDOptions) *Dentry {
inode := &StaticDirectory{}
- inode.Init(creds, devMajor, devMinor, ino, perm)
+ inode.Init(creds, devMajor, devMinor, ino, perm, fdOpts)
dentry := &Dentry{}
dentry.Init(inode)
@@ -576,16 +577,17 @@ func NewStaticDir(creds *auth.Credentials, devMajor, devMinor uint32, ino uint64
}
// Init initializes StaticDirectory.
-func (s *StaticDirectory) Init(creds *auth.Credentials, devMajor, devMinor uint32, ino uint64, perm linux.FileMode) {
+func (s *StaticDirectory) Init(creds *auth.Credentials, devMajor, devMinor uint32, ino uint64, perm linux.FileMode, fdOpts GenericDirectoryFDOptions) {
if perm&^linux.PermissionsMask != 0 {
panic(fmt.Sprintf("Only permission mask must be set: %x", perm&linux.PermissionsMask))
}
+ s.fdOpts = fdOpts
s.InodeAttrs.Init(creds, devMajor, devMinor, ino, linux.ModeDirectory|perm)
}
// Open implements kernfs.Inode.
func (s *StaticDirectory) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
- fd, err := NewGenericDirectoryFD(rp.Mount(), vfsd, &s.OrderedChildren, &s.locks, &opts)
+ fd, err := NewGenericDirectoryFD(rp.Mount(), vfsd, &s.OrderedChildren, &s.locks, &opts, s.fdOpts)
if err != nil {
return nil, err
}
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs_test.go b/pkg/sentry/fsimpl/kernfs/kernfs_test.go
index c5d5afedf..e5c28c0e4 100644
--- a/pkg/sentry/fsimpl/kernfs/kernfs_test.go
+++ b/pkg/sentry/fsimpl/kernfs/kernfs_test.go
@@ -119,7 +119,9 @@ func (fs *filesystem) newReadonlyDir(creds *auth.Credentials, mode linux.FileMod
}
func (d *readonlyDir) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
- fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &d.locks, &opts)
+ fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &d.locks, &opts, kernfs.GenericDirectoryFDOptions{
+ SeekEnd: kernfs.SeekEndStaticEntries,
+ })
if err != nil {
return nil, err
}
@@ -151,7 +153,9 @@ func (fs *filesystem) newDir(creds *auth.Credentials, mode linux.FileMode, conte
}
func (d *dir) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
- fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &d.locks, &opts)
+ fd, err := kernfs.NewGenericDirectoryFD(rp.Mount(), vfsd, &d.OrderedChildren, &d.locks, &opts, kernfs.GenericDirectoryFDOptions{
+ SeekEnd: kernfs.SeekEndStaticEntries,
+ })
if err != nil {
return nil, err
}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-12 20:40:14 +0000