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authorkevin.xu <cming.xu@gmail.com>2020-04-27 21:51:31 +0800
committerGitHub <noreply@github.com>2020-04-27 21:51:31 +0800
commite896ca54db67524afc20b644d43c72185e72dc0e (patch)
tree2a16f3a62a5cafd098f1f028c621f1b655589d69 /pkg/sentry/fsimpl/pipefs/pipefs.go
parent1f19624fa127d7d59cabe29593cc80b7fe6c81f8 (diff)
parent3c67754663f424f2ebbc0ff2a4c80e30618d5355 (diff)
Merge pull request #1 from google/master
catch up
Diffstat (limited to 'pkg/sentry/fsimpl/pipefs/pipefs.go')
-rw-r--r--pkg/sentry/fsimpl/pipefs/pipefs.go147
1 files changed, 147 insertions, 0 deletions
diff --git a/pkg/sentry/fsimpl/pipefs/pipefs.go b/pkg/sentry/fsimpl/pipefs/pipefs.go
new file mode 100644
index 000000000..d6bd67467
--- /dev/null
+++ b/pkg/sentry/fsimpl/pipefs/pipefs.go
@@ -0,0 +1,147 @@
+// Copyright 2020 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 pipefs provides the filesystem implementation backing
+// Kernel.PipeMount.
+package pipefs
+
+import (
+ "gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/context"
+ "gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
+ "gvisor.dev/gvisor/pkg/sentry/kernel/auth"
+ "gvisor.dev/gvisor/pkg/sentry/kernel/pipe"
+ ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
+ "gvisor.dev/gvisor/pkg/sentry/vfs"
+ "gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
+)
+
+type filesystemType struct{}
+
+// Name implements vfs.FilesystemType.Name.
+func (filesystemType) Name() string {
+ return "pipefs"
+}
+
+// GetFilesystem implements vfs.FilesystemType.GetFilesystem.
+func (filesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.VirtualFilesystem, creds *auth.Credentials, source string, opts vfs.GetFilesystemOptions) (*vfs.Filesystem, *vfs.Dentry, error) {
+ panic("pipefs.filesystemType.GetFilesystem should never be called")
+}
+
+// filesystem implements vfs.FilesystemImpl.
+type filesystem struct {
+ kernfs.Filesystem
+
+ // TODO(gvisor.dev/issue/1193):
+ //
+ // - kernfs does not provide a way to implement statfs, from which we
+ // should indicate PIPEFS_MAGIC.
+ //
+ // - kernfs does not provide a way to override names for
+ // vfs.FilesystemImpl.PrependPath(); pipefs inodes should use synthetic
+ // name fmt.Sprintf("pipe:[%d]", inode.ino).
+}
+
+// NewFilesystem sets up and returns a new vfs.Filesystem implemented by
+// pipefs.
+func NewFilesystem(vfsObj *vfs.VirtualFilesystem) *vfs.Filesystem {
+ fs := &filesystem{}
+ fs.Init(vfsObj, filesystemType{})
+ return fs.VFSFilesystem()
+}
+
+// inode implements kernfs.Inode.
+type inode struct {
+ kernfs.InodeNotDirectory
+ kernfs.InodeNotSymlink
+ kernfs.InodeNoopRefCount
+
+ pipe *pipe.VFSPipe
+
+ ino uint64
+ uid auth.KUID
+ gid auth.KGID
+ // We use the creation timestamp for all of atime, mtime, and ctime.
+ ctime ktime.Time
+}
+
+func newInode(ctx context.Context, fs *kernfs.Filesystem) *inode {
+ creds := auth.CredentialsFromContext(ctx)
+ return &inode{
+ pipe: pipe.NewVFSPipe(false /* isNamed */, pipe.DefaultPipeSize, usermem.PageSize),
+ ino: fs.NextIno(),
+ uid: creds.EffectiveKUID,
+ gid: creds.EffectiveKGID,
+ ctime: ktime.NowFromContext(ctx),
+ }
+}
+
+const pipeMode = 0600 | linux.S_IFIFO
+
+// CheckPermissions implements kernfs.Inode.CheckPermissions.
+func (i *inode) CheckPermissions(ctx context.Context, creds *auth.Credentials, ats vfs.AccessTypes) error {
+ return vfs.GenericCheckPermissions(creds, ats, pipeMode, i.uid, i.gid)
+}
+
+// Mode implements kernfs.Inode.Mode.
+func (i *inode) Mode() linux.FileMode {
+ return pipeMode
+}
+
+// Stat implements kernfs.Inode.Stat.
+func (i *inode) Stat(vfsfs *vfs.Filesystem, opts vfs.StatOptions) (linux.Statx, error) {
+ ts := linux.NsecToStatxTimestamp(i.ctime.Nanoseconds())
+ return linux.Statx{
+ Mask: linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_NLINK | linux.STATX_UID | linux.STATX_GID | linux.STATX_ATIME | linux.STATX_MTIME | linux.STATX_CTIME | linux.STATX_INO | linux.STATX_SIZE | linux.STATX_BLOCKS,
+ Blksize: usermem.PageSize,
+ Nlink: 1,
+ UID: uint32(i.uid),
+ GID: uint32(i.gid),
+ Mode: pipeMode,
+ Ino: i.ino,
+ Size: 0,
+ Blocks: 0,
+ Atime: ts,
+ Ctime: ts,
+ Mtime: ts,
+ // TODO(gvisor.dev/issue/1197): Device number.
+ }, nil
+}
+
+// SetStat implements kernfs.Inode.SetStat.
+func (i *inode) SetStat(ctx context.Context, vfsfs *vfs.Filesystem, creds *auth.Credentials, opts vfs.SetStatOptions) error {
+ if opts.Stat.Mask == 0 {
+ return nil
+ }
+ return syserror.EPERM
+}
+
+// Open implements kernfs.Inode.Open.
+func (i *inode) Open(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry, opts vfs.OpenOptions) (*vfs.FileDescription, error) {
+ return i.pipe.Open(ctx, rp.Mount(), vfsd, opts.Flags)
+}
+
+// NewConnectedPipeFDs returns a pair of FileDescriptions representing the read
+// and write ends of a newly-created pipe, as for pipe(2) and pipe2(2).
+//
+// Preconditions: mnt.Filesystem() must have been returned by NewFilesystem().
+func NewConnectedPipeFDs(ctx context.Context, mnt *vfs.Mount, flags uint32) (*vfs.FileDescription, *vfs.FileDescription) {
+ fs := mnt.Filesystem().Impl().(*kernfs.Filesystem)
+ inode := newInode(ctx, fs)
+ var d kernfs.Dentry
+ d.Init(inode)
+ defer d.DecRef()
+ return inode.pipe.ReaderWriterPair(mnt, d.VFSDentry(), flags)
+}