diff options
Diffstat (limited to 'pkg/sentry/fsimpl/ext/inode.go')
-rw-r--r-- | pkg/sentry/fsimpl/ext/inode.go | 222 |
1 files changed, 0 insertions, 222 deletions
diff --git a/pkg/sentry/fsimpl/ext/inode.go b/pkg/sentry/fsimpl/ext/inode.go deleted file mode 100644 index b2cc826c7..000000000 --- a/pkg/sentry/fsimpl/ext/inode.go +++ /dev/null @@ -1,222 +0,0 @@ -// 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 ext - -import ( - "fmt" - "sync/atomic" - - "gvisor.dev/gvisor/pkg/abi/linux" - "gvisor.dev/gvisor/pkg/sentry/fsimpl/ext/disklayout" - "gvisor.dev/gvisor/pkg/sentry/kernel/auth" - "gvisor.dev/gvisor/pkg/sentry/vfs" - "gvisor.dev/gvisor/pkg/syserror" -) - -// inode represents an ext inode. -// -// inode uses the same inheritance pattern that pkg/sentry/vfs structures use. -// This has been done to increase memory locality. -// -// Implementations: -// inode -- -// |-- dir -// |-- symlink -// |-- regular-- -// |-- extent file -// |-- block map file -type inode struct { - // refs is a reference count. refs is accessed using atomic memory operations. - refs int64 - - // fs is the containing filesystem. - fs *filesystem - - // inodeNum is the inode number of this inode on disk. This is used to - // identify inodes within the ext filesystem. - inodeNum uint32 - - // blkSize is the fs data block size. Same as filesystem.sb.BlockSize(). - blkSize uint64 - - // diskInode gives us access to the inode struct on disk. Immutable. - diskInode disklayout.Inode - - // This is immutable. The first field of the implementations must have inode - // as the first field to ensure temporality. - impl interface{} -} - -// incRef increments the inode ref count. -func (in *inode) incRef() { - atomic.AddInt64(&in.refs, 1) -} - -// tryIncRef tries to increment the ref count. Returns true if successful. -func (in *inode) tryIncRef() bool { - for { - refs := atomic.LoadInt64(&in.refs) - if refs == 0 { - return false - } - if atomic.CompareAndSwapInt64(&in.refs, refs, refs+1) { - return true - } - } -} - -// decRef decrements the inode ref count and releases the inode resources if -// the ref count hits 0. -// -// Precondition: Must have locked filesystem.mu. -func (in *inode) decRef() { - if refs := atomic.AddInt64(&in.refs, -1); refs == 0 { - delete(in.fs.inodeCache, in.inodeNum) - } else if refs < 0 { - panic("ext.inode.decRef() called without holding a reference") - } -} - -// newInode is the inode constructor. Reads the inode off disk. Identifies -// inodes based on the absolute inode number on disk. -func newInode(fs *filesystem, inodeNum uint32) (*inode, error) { - if inodeNum == 0 { - panic("inode number 0 on ext filesystems is not possible") - } - - inodeRecordSize := fs.sb.InodeSize() - var diskInode disklayout.Inode - if inodeRecordSize == disklayout.OldInodeSize { - diskInode = &disklayout.InodeOld{} - } else { - diskInode = &disklayout.InodeNew{} - } - - // Calculate where the inode is actually placed. - inodesPerGrp := fs.sb.InodesPerGroup() - blkSize := fs.sb.BlockSize() - inodeTableOff := fs.bgs[getBGNum(inodeNum, inodesPerGrp)].InodeTable() * blkSize - inodeOff := inodeTableOff + uint64(uint32(inodeRecordSize)*getBGOff(inodeNum, inodesPerGrp)) - - if err := readFromDisk(fs.dev, int64(inodeOff), diskInode); err != nil { - return nil, err - } - - // Build the inode based on its type. - inode := inode{ - fs: fs, - inodeNum: inodeNum, - blkSize: blkSize, - diskInode: diskInode, - } - - switch diskInode.Mode().FileType() { - case linux.ModeSymlink: - f, err := newSymlink(inode) - if err != nil { - return nil, err - } - return &f.inode, nil - case linux.ModeRegular: - f, err := newRegularFile(inode) - if err != nil { - return nil, err - } - return &f.inode, nil - case linux.ModeDirectory: - f, err := newDirectroy(inode, fs.sb.IncompatibleFeatures().DirentFileType) - if err != nil { - return nil, err - } - return &f.inode, nil - default: - // TODO(b/134676337): Return appropriate errors for sockets, pipes and devices. - return nil, syserror.EINVAL - } -} - -// open creates and returns a file description for the dentry passed in. -func (in *inode) open(rp *vfs.ResolvingPath, vfsd *vfs.Dentry, flags uint32) (*vfs.FileDescription, error) { - ats := vfs.AccessTypesForOpenFlags(flags) - if err := in.checkPermissions(rp.Credentials(), ats); err != nil { - return nil, err - } - mnt := rp.Mount() - switch in.impl.(type) { - case *regularFile: - var fd regularFileFD - mnt.IncRef() - vfsd.IncRef() - fd.vfsfd.Init(&fd, flags, mnt, vfsd, &vfs.FileDescriptionOptions{}) - return &fd.vfsfd, nil - case *directory: - // Can't open directories writably. This check is not necessary for a read - // only filesystem but will be required when write is implemented. - if ats&vfs.MayWrite != 0 { - return nil, syserror.EISDIR - } - var fd directoryFD - mnt.IncRef() - vfsd.IncRef() - fd.vfsfd.Init(&fd, flags, mnt, vfsd, &vfs.FileDescriptionOptions{}) - return &fd.vfsfd, nil - case *symlink: - if flags&linux.O_PATH == 0 { - // Can't open symlinks without O_PATH. - return nil, syserror.ELOOP - } - var fd symlinkFD - mnt.IncRef() - vfsd.IncRef() - fd.vfsfd.Init(&fd, flags, mnt, vfsd, &vfs.FileDescriptionOptions{}) - return &fd.vfsfd, nil - default: - panic(fmt.Sprintf("unknown inode type: %T", in.impl)) - } -} - -func (in *inode) checkPermissions(creds *auth.Credentials, ats vfs.AccessTypes) error { - return vfs.GenericCheckPermissions(creds, ats, in.isDir(), uint16(in.diskInode.Mode()), in.diskInode.UID(), in.diskInode.GID()) -} - -// statTo writes the statx fields to the output parameter. -func (in *inode) statTo(stat *linux.Statx) { - stat.Mask = linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_NLINK | - linux.STATX_UID | linux.STATX_GID | linux.STATX_INO | linux.STATX_SIZE | - linux.STATX_ATIME | linux.STATX_CTIME | linux.STATX_MTIME - stat.Blksize = uint32(in.blkSize) - stat.Mode = uint16(in.diskInode.Mode()) - stat.Nlink = uint32(in.diskInode.LinksCount()) - stat.UID = uint32(in.diskInode.UID()) - stat.GID = uint32(in.diskInode.GID()) - stat.Ino = uint64(in.inodeNum) - stat.Size = in.diskInode.Size() - stat.Atime = in.diskInode.AccessTime().StatxTimestamp() - stat.Ctime = in.diskInode.ChangeTime().StatxTimestamp() - stat.Mtime = in.diskInode.ModificationTime().StatxTimestamp() - // TODO(b/134676337): Set stat.Blocks which is the number of 512 byte blocks - // (including metadata blocks) required to represent this file. -} - -// getBGNum returns the block group number that a given inode belongs to. -func getBGNum(inodeNum uint32, inodesPerGrp uint32) uint32 { - return (inodeNum - 1) / inodesPerGrp -} - -// getBGOff returns the offset at which the given inode lives in the block -// group's inode table, i.e. the index of the inode in the inode table. -func getBGOff(inodeNum uint32, inodesPerGrp uint32) uint32 { - return (inodeNum - 1) % inodesPerGrp -} |