1 files changed, 235 insertions, 0 deletions
diff --git a/pkg/sentry/vfs/options.go b/pkg/sentry/vfs/options.go
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+++ b/pkg/sentry/vfs/options.go
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+// Copyright 2019 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package vfs
+
+import (
+	"gvisor.dev/gvisor/pkg/abi/linux"
+	"gvisor.dev/gvisor/pkg/sentry/socket/unix/transport"
+)
+
+// GetDentryOptions contains options to VirtualFilesystem.GetDentryAt() and
+// FilesystemImpl.GetDentryAt().
+type GetDentryOptions struct {
+	// If CheckSearchable is true, FilesystemImpl.GetDentryAt() must check that
+	// the returned Dentry is a directory for which creds has search
+	// permission.
+	CheckSearchable bool
+}
+
+// MkdirOptions contains options to VirtualFilesystem.MkdirAt() and
+// FilesystemImpl.MkdirAt().
+type MkdirOptions struct {
+	// Mode is the file mode bits for the created directory.
+	Mode linux.FileMode
+
+	// If ForSyntheticMountpoint is true, FilesystemImpl.MkdirAt() may create
+	// the given directory in memory only (as opposed to persistent storage).
+	// The created directory should be able to support the creation of
+	// subdirectories with ForSyntheticMountpoint == true. It does not need to
+	// support the creation of subdirectories with ForSyntheticMountpoint ==
+	// false, or files of other types.
+	//
+	// FilesystemImpls are permitted to ignore the ForSyntheticMountpoint
+	// option.
+	//
+	// The ForSyntheticMountpoint option exists because, unlike mount(2), the
+	// OCI Runtime Specification permits the specification of mount points that
+	// do not exist, under the expectation that container runtimes will create
+	// them. (More accurately, the OCI Runtime Specification completely fails
+	// to document this feature, but it's implemented by runc.)
+	// ForSyntheticMountpoint allows such mount points to be created even when
+	// the underlying persistent filesystem is immutable.
+	ForSyntheticMountpoint bool
+}
+
+// MknodOptions contains options to VirtualFilesystem.MknodAt() and
+// FilesystemImpl.MknodAt().
+type MknodOptions struct {
+	// Mode is the file type and mode bits for the created file.
+	Mode linux.FileMode
+
+	// If Mode specifies a character or block device special file, DevMajor and
+	// DevMinor are the major and minor device numbers for the created device.
+	DevMajor uint32
+	DevMinor uint32
+
+	// Endpoint is the endpoint to bind to the created file, if a socket file is
+	// being created for bind(2) on a Unix domain socket.
+	Endpoint transport.BoundEndpoint
+}
+
+// MountFlags contains flags as specified for mount(2), e.g. MS_NOEXEC.
+// MS_RDONLY is not part of MountFlags because it's tracked in Mount.writers.
+type MountFlags struct {
+	// NoExec is equivalent to MS_NOEXEC.
+	NoExec bool
+
+	// NoATime is equivalent to MS_NOATIME and indicates that the
+	// filesystem should not update access time in-place.
+	NoATime bool
+}
+
+// MountOptions contains options to VirtualFilesystem.MountAt().
+type MountOptions struct {
+	// Flags contains flags as specified for mount(2), e.g. MS_NOEXEC.
+	Flags MountFlags
+
+	// ReadOnly is equivalent to MS_RDONLY.
+	ReadOnly bool
+
+	// GetFilesystemOptions contains options to FilesystemType.GetFilesystem().
+	GetFilesystemOptions GetFilesystemOptions
+
+	// If InternalMount is true, allow the use of filesystem types for which
+	// RegisterFilesystemTypeOptions.AllowUserMount == false.
+	InternalMount bool
+}
+
+// OpenOptions contains options to VirtualFilesystem.OpenAt() and
+// FilesystemImpl.OpenAt().
+type OpenOptions struct {
+	// Flags contains access mode and flags as specified for open(2).
+	//
+	// FilesystemImpls are responsible for implementing the following flags:
+	// O_RDONLY, O_WRONLY, O_RDWR, O_APPEND, O_CREAT, O_DIRECT, O_DSYNC,
+	// O_EXCL, O_NOATIME, O_NOCTTY, O_NONBLOCK, O_PATH, O_SYNC, O_TMPFILE, and
+	// O_TRUNC. VFS is responsible for handling O_DIRECTORY, O_LARGEFILE, and
+	// O_NOFOLLOW. VFS users are responsible for handling O_CLOEXEC, since file
+	// descriptors are mostly outside the scope of VFS.
+	Flags uint32
+
+	// If FilesystemImpl.OpenAt() creates a file, Mode is the file mode for the
+	// created file.
+	Mode linux.FileMode
+
+	// FileExec is set when the file is being opened to be executed.
+	// VirtualFilesystem.OpenAt() checks that the caller has execute permissions
+	// on the file, that the file is a regular file, and that the mount doesn't
+	// have MS_NOEXEC set.
+	FileExec bool
+}
+
+// ReadOptions contains options to FileDescription.PRead(),
+// FileDescriptionImpl.PRead(), FileDescription.Read(), and
+// FileDescriptionImpl.Read().
+type ReadOptions struct {
+	// Flags contains flags as specified for preadv2(2).
+	Flags uint32
+}
+
+// RenameOptions contains options to VirtualFilesystem.RenameAt() and
+// FilesystemImpl.RenameAt().
+type RenameOptions struct {
+	// Flags contains flags as specified for renameat2(2).
+	Flags uint32
+
+	// If MustBeDir is true, the renamed file must be a directory.
+	MustBeDir bool
+}
+
+// SetStatOptions contains options to VirtualFilesystem.SetStatAt(),
+// FilesystemImpl.SetStatAt(), FileDescription.SetStat(), and
+// FileDescriptionImpl.SetStat().
+type SetStatOptions struct {
+	// Stat is the metadata that should be set. Only fields indicated by
+	// Stat.Mask should be set.
+	//
+	// If Stat specifies that a timestamp should be set,
+	// FilesystemImpl.SetStatAt() and FileDescriptionImpl.SetStat() must
+	// special-case StatxTimestamp.Nsec == UTIME_NOW as described by
+	// utimensat(2); however, they do not need to check for StatxTimestamp.Nsec
+	// == UTIME_OMIT (VFS users must unset the corresponding bit in Stat.Mask
+	// instead).
+	Stat linux.Statx
+}
+
+// BoundEndpointOptions contains options to VirtualFilesystem.BoundEndpointAt()
+// and FilesystemImpl.BoundEndpointAt().
+type BoundEndpointOptions struct {
+	// Addr is the path of the file whose socket endpoint is being retrieved.
+	// It is generally irrelevant: most endpoints are stored at a dentry that
+	// was created through a bind syscall, so the path can be stored on creation.
+	// However, if the endpoint was created in FilesystemImpl.BoundEndpointAt(),
+	// then we may not know what the original bind address was.
+	//
+	// For example, if connect(2) is called with address "foo" which corresponds
+	// a remote named socket in goferfs, we need to generate an endpoint wrapping
+	// that file. In this case, we can use Addr to set the endpoint address to
+	// "foo". Note that Addr is only a best-effort attempt--we still do not know
+	// the exact address that was used on the remote fs to bind the socket (it
+	// may have been "foo", "./foo", etc.).
+	Addr string
+}
+
+// GetxattrOptions contains options to VirtualFilesystem.GetxattrAt(),
+// FilesystemImpl.GetxattrAt(), FileDescription.Getxattr(), and
+// FileDescriptionImpl.Getxattr().
+type GetxattrOptions struct {
+	// Name is the name of the extended attribute to retrieve.
+	Name string
+
+	// Size is the maximum value size that the caller will tolerate. If the value
+	// is larger than size, getxattr methods may return ERANGE, but they are also
+	// free to ignore the hint entirely (i.e. the value returned may be larger
+	// than size). All size checking is done independently at the syscall layer.
+	Size uint64
+}
+
+// SetxattrOptions contains options to VirtualFilesystem.SetxattrAt(),
+// FilesystemImpl.SetxattrAt(), FileDescription.Setxattr(), and
+// FileDescriptionImpl.Setxattr().
+type SetxattrOptions struct {
+	// Name is the name of the extended attribute being mutated.
+	Name string
+
+	// Value is the extended attribute's new value.
+	Value string
+
+	// Flags contains flags as specified for setxattr/lsetxattr/fsetxattr(2).
+	Flags uint32
+}
+
+// StatOptions contains options to VirtualFilesystem.StatAt(),
+// FilesystemImpl.StatAt(), FileDescription.Stat(), and
+// FileDescriptionImpl.Stat().
+type StatOptions struct {
+	// Mask is the set of fields in the returned Statx that the FilesystemImpl
+	// or FileDescriptionImpl should provide. Bits are as in linux.Statx.Mask.
+	//
+	// The FilesystemImpl or FileDescriptionImpl may return fields not
+	// requested in Mask, and may fail to return fields requested in Mask that
+	// are not supported by the underlying filesystem implementation, without
+	// returning an error.
+	Mask uint32
+
+	// Sync specifies the synchronization required, and is one of
+	// linux.AT_STATX_SYNC_AS_STAT (which is 0, and therefore the default),
+	// linux.AT_STATX_SYNC_FORCE_SYNC, or linux.AT_STATX_SYNC_DONT_SYNC.
+	Sync uint32
+}
+
+// UmountOptions contains options to VirtualFilesystem.UmountAt().
+type UmountOptions struct {
+	// Flags contains flags as specified for umount2(2).
+	Flags uint32
+}
+
+// WriteOptions contains options to FileDescription.PWrite(),
+// FileDescriptionImpl.PWrite(), FileDescription.Write(), and
+// FileDescriptionImpl.Write().
+type WriteOptions struct {
+	// Flags contains flags as specified for pwritev2(2).
+	Flags uint32
+}