diff options
Diffstat (limited to 'pkg/sentry/fsimpl/kernfs/filesystem.go')
| -rw-r--r-- | pkg/sentry/fsimpl/kernfs/filesystem.go | 691 |
1 files changed, 0 insertions, 691 deletions
diff --git a/pkg/sentry/fsimpl/kernfs/filesystem.go b/pkg/sentry/fsimpl/kernfs/filesystem.go deleted file mode 100644 index db486b6c1..000000000 --- a/pkg/sentry/fsimpl/kernfs/filesystem.go +++ /dev/null @@ -1,691 +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. - -// This file implements vfs.FilesystemImpl for kernfs. - -package kernfs - -import ( - "fmt" - - "gvisor.dev/gvisor/pkg/abi/linux" - "gvisor.dev/gvisor/pkg/fspath" - "gvisor.dev/gvisor/pkg/sentry/context" - "gvisor.dev/gvisor/pkg/sentry/kernel/auth" - "gvisor.dev/gvisor/pkg/sentry/vfs" - "gvisor.dev/gvisor/pkg/syserror" -) - -// stepExistingLocked resolves rp.Component() in parent directory vfsd. -// -// stepExistingLocked is loosely analogous to fs/namei.c:walk_component(). -// -// Preconditions: Filesystem.mu must be locked for at least reading. !rp.Done(). -// -// Postcondition: Caller must call fs.processDeferredDecRefs*. -func (fs *Filesystem) stepExistingLocked(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry) (*vfs.Dentry, error) { - d := vfsd.Impl().(*Dentry) - if !d.isDir() { - return nil, syserror.ENOTDIR - } - // Directory searchable? - if err := d.inode.CheckPermissions(rp.Credentials(), vfs.MayExec); err != nil { - return nil, err - } -afterSymlink: - d.dirMu.Lock() - nextVFSD, err := rp.ResolveComponent(vfsd) - d.dirMu.Unlock() - if err != nil { - return nil, err - } - if nextVFSD != nil { - // Cached dentry exists, revalidate. - next := nextVFSD.Impl().(*Dentry) - if !next.inode.Valid(ctx) { - d.dirMu.Lock() - rp.VirtualFilesystem().ForceDeleteDentry(nextVFSD) - d.dirMu.Unlock() - fs.deferDecRef(nextVFSD) // Reference from Lookup. - nextVFSD = nil - } - } - if nextVFSD == nil { - // Dentry isn't cached; it either doesn't exist or failed - // revalidation. Attempt to resolve it via Lookup. - name := rp.Component() - var err error - nextVFSD, err = d.inode.Lookup(ctx, name) - // Reference on nextVFSD dropped by a corresponding Valid. - if err != nil { - return nil, err - } - d.InsertChild(name, nextVFSD) - } - next := nextVFSD.Impl().(*Dentry) - - // Resolve any symlink at current path component. - if rp.ShouldFollowSymlink() && d.isSymlink() { - // TODO: VFS2 needs something extra for /proc/[pid]/fd/ "magic symlinks". - target, err := next.inode.Readlink(ctx) - if err != nil { - return nil, err - } - if err := rp.HandleSymlink(target); err != nil { - return nil, err - } - goto afterSymlink - - } - rp.Advance() - return nextVFSD, nil -} - -// walkExistingLocked resolves rp to an existing file. -// -// walkExistingLocked is loosely analogous to Linux's -// fs/namei.c:path_lookupat(). -// -// Preconditions: Filesystem.mu must be locked for at least reading. -// -// Postconditions: Caller must call fs.processDeferredDecRefs*. -func (fs *Filesystem) walkExistingLocked(ctx context.Context, rp *vfs.ResolvingPath) (*vfs.Dentry, Inode, error) { - vfsd := rp.Start() - for !rp.Done() { - var err error - vfsd, err = fs.stepExistingLocked(ctx, rp, vfsd) - if err != nil { - return nil, nil, err - } - } - d := vfsd.Impl().(*Dentry) - if rp.MustBeDir() && !d.isDir() { - return nil, nil, syserror.ENOTDIR - } - return vfsd, d.inode, nil -} - -// walkParentDirLocked resolves all but the last path component of rp to an -// existing directory. It does not check that the returned directory is -// searchable by the provider of rp. -// -// walkParentDirLocked is loosely analogous to Linux's -// fs/namei.c:path_parentat(). -// -// Preconditions: Filesystem.mu must be locked for at least reading. !rp.Done(). -// -// Postconditions: Caller must call fs.processDeferredDecRefs*. -func (fs *Filesystem) walkParentDirLocked(ctx context.Context, rp *vfs.ResolvingPath) (*vfs.Dentry, Inode, error) { - vfsd := rp.Start() - for !rp.Final() { - var err error - vfsd, err = fs.stepExistingLocked(ctx, rp, vfsd) - if err != nil { - return nil, nil, err - } - } - d := vfsd.Impl().(*Dentry) - if !d.isDir() { - return nil, nil, syserror.ENOTDIR - } - return vfsd, d.inode, nil -} - -// checkCreateLocked checks that a file named rp.Component() may be created in -// directory parentVFSD, then returns rp.Component(). -// -// Preconditions: Filesystem.mu must be locked for at least reading. parentInode -// == parentVFSD.Impl().(*Dentry).Inode. isDir(parentInode) == true. -func checkCreateLocked(rp *vfs.ResolvingPath, parentVFSD *vfs.Dentry, parentInode Inode) (string, error) { - if err := parentInode.CheckPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil { - return "", err - } - pc := rp.Component() - if pc == "." || pc == ".." { - return "", syserror.EEXIST - } - childVFSD, err := rp.ResolveChild(parentVFSD, pc) - if err != nil { - return "", err - } - if childVFSD != nil { - return "", syserror.EEXIST - } - if parentVFSD.IsDisowned() { - return "", syserror.ENOENT - } - return pc, nil -} - -// checkDeleteLocked checks that the file represented by vfsd may be deleted. -// -// Preconditions: Filesystem.mu must be locked for at least reading. -func checkDeleteLocked(rp *vfs.ResolvingPath, vfsd *vfs.Dentry) error { - parentVFSD := vfsd.Parent() - if parentVFSD == nil { - return syserror.EBUSY - } - if parentVFSD.IsDisowned() { - return syserror.ENOENT - } - if err := parentVFSD.Impl().(*Dentry).inode.CheckPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil { - return err - } - return nil -} - -// checkRenameLocked checks that a rename operation may be performed on the -// target dentry across the given set of parent directories. The target dentry -// may be nil. -// -// Precondition: isDir(dstInode) == true. -func checkRenameLocked(creds *auth.Credentials, src, dstDir *vfs.Dentry, dstInode Inode) error { - srcDir := src.Parent() - if srcDir == nil { - return syserror.EBUSY - } - if srcDir.IsDisowned() { - return syserror.ENOENT - } - if dstDir.IsDisowned() { - return syserror.ENOENT - } - // Check for creation permissions on dst dir. - if err := dstInode.CheckPermissions(creds, vfs.MayWrite|vfs.MayExec); err != nil { - return err - } - - return nil -} - -// Release implements vfs.FilesystemImpl.Release. -func (fs *Filesystem) Release() { -} - -// Sync implements vfs.FilesystemImpl.Sync. -func (fs *Filesystem) Sync(ctx context.Context) error { - // All filesystem state is in-memory. - return nil -} - -// GetDentryAt implements vfs.FilesystemImpl.GetDentryAt. -func (fs *Filesystem) GetDentryAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.GetDentryOptions) (*vfs.Dentry, error) { - fs.mu.RLock() - defer fs.processDeferredDecRefs() - defer fs.mu.RUnlock() - vfsd, inode, err := fs.walkExistingLocked(ctx, rp) - if err != nil { - return nil, err - } - - if opts.CheckSearchable { - d := vfsd.Impl().(*Dentry) - if !d.isDir() { - return nil, syserror.ENOTDIR - } - if err := inode.CheckPermissions(rp.Credentials(), vfs.MayExec); err != nil { - return nil, err - } - } - vfsd.IncRef() // Ownership transferred to caller. - return vfsd, nil -} - -// LinkAt implements vfs.FilesystemImpl.LinkAt. -func (fs *Filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.VirtualDentry) error { - if rp.Done() { - return syserror.EEXIST - } - fs.mu.Lock() - defer fs.mu.Unlock() - parentVFSD, parentInode, err := fs.walkParentDirLocked(ctx, rp) - fs.processDeferredDecRefsLocked() - if err != nil { - return err - } - pc, err := checkCreateLocked(rp, parentVFSD, parentInode) - if err != nil { - return err - } - if rp.Mount() != vd.Mount() { - return syserror.EXDEV - } - if err := rp.Mount().CheckBeginWrite(); err != nil { - return err - } - defer rp.Mount().EndWrite() - - d := vd.Dentry().Impl().(*Dentry) - if d.isDir() { - return syserror.EPERM - } - - child, err := parentInode.NewLink(ctx, pc, d.inode) - if err != nil { - return err - } - parentVFSD.Impl().(*Dentry).InsertChild(pc, child) - return nil -} - -// MkdirAt implements vfs.FilesystemImpl.MkdirAt. -func (fs *Filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MkdirOptions) error { - if rp.Done() { - return syserror.EEXIST - } - fs.mu.Lock() - defer fs.mu.Unlock() - parentVFSD, parentInode, err := fs.walkParentDirLocked(ctx, rp) - fs.processDeferredDecRefsLocked() - if err != nil { - return err - } - pc, err := checkCreateLocked(rp, parentVFSD, parentInode) - if err != nil { - return err - } - if err := rp.Mount().CheckBeginWrite(); err != nil { - return err - } - defer rp.Mount().EndWrite() - child, err := parentInode.NewDir(ctx, pc, opts) - if err != nil { - return err - } - parentVFSD.Impl().(*Dentry).InsertChild(pc, child) - return nil -} - -// MknodAt implements vfs.FilesystemImpl.MknodAt. -func (fs *Filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MknodOptions) error { - if rp.Done() { - return syserror.EEXIST - } - fs.mu.Lock() - defer fs.mu.Unlock() - parentVFSD, parentInode, err := fs.walkParentDirLocked(ctx, rp) - fs.processDeferredDecRefsLocked() - if err != nil { - return err - } - pc, err := checkCreateLocked(rp, parentVFSD, parentInode) - if err != nil { - return err - } - if err := rp.Mount().CheckBeginWrite(); err != nil { - return err - } - defer rp.Mount().EndWrite() - new, err := parentInode.NewNode(ctx, pc, opts) - if err != nil { - return err - } - parentVFSD.Impl().(*Dentry).InsertChild(pc, new) - return nil -} - -// OpenAt implements vfs.FilesystemImpl.OpenAt. -func (fs *Filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.OpenOptions) (*vfs.FileDescription, error) { - // Filter out flags that are not supported by kernfs. O_DIRECTORY and - // O_NOFOLLOW have no effect here (they're handled by VFS by setting - // appropriate bits in rp), but are returned by - // FileDescriptionImpl.StatusFlags(). - opts.Flags &= linux.O_ACCMODE | linux.O_CREAT | linux.O_EXCL | linux.O_TRUNC | linux.O_DIRECTORY | linux.O_NOFOLLOW - ats := vfs.AccessTypesForOpenFlags(opts.Flags) - - // Do not create new file. - if opts.Flags&linux.O_CREAT == 0 { - fs.mu.RLock() - defer fs.processDeferredDecRefs() - defer fs.mu.RUnlock() - vfsd, inode, err := fs.walkExistingLocked(ctx, rp) - if err != nil { - return nil, err - } - if err := inode.CheckPermissions(rp.Credentials(), ats); err != nil { - return nil, err - } - return inode.Open(rp, vfsd, opts.Flags) - } - - // May create new file. - mustCreate := opts.Flags&linux.O_EXCL != 0 - vfsd := rp.Start() - inode := vfsd.Impl().(*Dentry).inode - fs.mu.Lock() - defer fs.mu.Unlock() - if rp.Done() { - if rp.MustBeDir() { - return nil, syserror.EISDIR - } - if mustCreate { - return nil, syserror.EEXIST - } - if err := inode.CheckPermissions(rp.Credentials(), ats); err != nil { - return nil, err - } - return inode.Open(rp, vfsd, opts.Flags) - } -afterTrailingSymlink: - parentVFSD, parentInode, err := fs.walkParentDirLocked(ctx, rp) - fs.processDeferredDecRefsLocked() - if err != nil { - return nil, err - } - // Check for search permission in the parent directory. - if err := parentInode.CheckPermissions(rp.Credentials(), vfs.MayExec); err != nil { - return nil, err - } - // Reject attempts to open directories with O_CREAT. - if rp.MustBeDir() { - return nil, syserror.EISDIR - } - pc := rp.Component() - if pc == "." || pc == ".." { - return nil, syserror.EISDIR - } - // Determine whether or not we need to create a file. - childVFSD, err := rp.ResolveChild(parentVFSD, pc) - if err != nil { - return nil, err - } - if childVFSD == nil { - // Already checked for searchability above; now check for writability. - if err := parentInode.CheckPermissions(rp.Credentials(), vfs.MayWrite); err != nil { - return nil, err - } - if err := rp.Mount().CheckBeginWrite(); err != nil { - return nil, err - } - defer rp.Mount().EndWrite() - // Create and open the child. - child, err := parentInode.NewFile(ctx, pc, opts) - if err != nil { - return nil, err - } - parentVFSD.Impl().(*Dentry).InsertChild(pc, child) - return child.Impl().(*Dentry).inode.Open(rp, child, opts.Flags) - } - // Open existing file or follow symlink. - if mustCreate { - return nil, syserror.EEXIST - } - childDentry := childVFSD.Impl().(*Dentry) - childInode := childDentry.inode - if rp.ShouldFollowSymlink() { - if childDentry.isSymlink() { - target, err := childInode.Readlink(ctx) - if err != nil { - return nil, err - } - if err := rp.HandleSymlink(target); err != nil { - return nil, err - } - // rp.Final() may no longer be true since we now need to resolve the - // symlink target. - goto afterTrailingSymlink - } - } - if err := childInode.CheckPermissions(rp.Credentials(), ats); err != nil { - return nil, err - } - return childInode.Open(rp, childVFSD, opts.Flags) -} - -// ReadlinkAt implements vfs.FilesystemImpl.ReadlinkAt. -func (fs *Filesystem) ReadlinkAt(ctx context.Context, rp *vfs.ResolvingPath) (string, error) { - fs.mu.RLock() - d, inode, err := fs.walkExistingLocked(ctx, rp) - fs.mu.RUnlock() - fs.processDeferredDecRefs() - if err != nil { - return "", err - } - if !d.Impl().(*Dentry).isSymlink() { - return "", syserror.EINVAL - } - return inode.Readlink(ctx) -} - -// RenameAt implements vfs.FilesystemImpl.RenameAt. -func (fs *Filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.VirtualDentry, opts vfs.RenameOptions) error { - noReplace := opts.Flags&linux.RENAME_NOREPLACE != 0 - exchange := opts.Flags&linux.RENAME_EXCHANGE != 0 - whiteout := opts.Flags&linux.RENAME_WHITEOUT != 0 - if exchange && (noReplace || whiteout) { - // Can't specify RENAME_NOREPLACE or RENAME_WHITEOUT with RENAME_EXCHANGE. - return syserror.EINVAL - } - if exchange || whiteout { - // Exchange and Whiteout flags are not supported on kernfs. - return syserror.EINVAL - } - - fs.mu.Lock() - defer fs.mu.Lock() - - mnt := rp.Mount() - if mnt != vd.Mount() { - return syserror.EXDEV - } - - if err := mnt.CheckBeginWrite(); err != nil { - return err - } - defer mnt.EndWrite() - - dstDirVFSD, dstDirInode, err := fs.walkParentDirLocked(ctx, rp) - fs.processDeferredDecRefsLocked() - if err != nil { - return err - } - - srcVFSD := vd.Dentry() - srcDirVFSD := srcVFSD.Parent() - - // Can we remove the src dentry? - if err := checkDeleteLocked(rp, srcVFSD); err != nil { - return err - } - - // Can we create the dst dentry? - var dstVFSD *vfs.Dentry - pc, err := checkCreateLocked(rp, dstDirVFSD, dstDirInode) - switch err { - case nil: - // Ok, continue with rename as replacement. - case syserror.EEXIST: - if noReplace { - // Won't overwrite existing node since RENAME_NOREPLACE was requested. - return syserror.EEXIST - } - dstVFSD, err = rp.ResolveChild(dstDirVFSD, pc) - if err != nil { - panic(fmt.Sprintf("Child %q for parent Dentry %+v disappeared inside atomic section?", pc, dstDirVFSD)) - } - default: - return err - } - - mntns := vfs.MountNamespaceFromContext(ctx) - virtfs := rp.VirtualFilesystem() - - srcDirDentry := srcDirVFSD.Impl().(*Dentry) - dstDirDentry := dstDirVFSD.Impl().(*Dentry) - - // We can't deadlock here due to lock ordering because we're protected from - // concurrent renames by fs.mu held for writing. - srcDirDentry.dirMu.Lock() - defer srcDirDentry.dirMu.Unlock() - dstDirDentry.dirMu.Lock() - defer dstDirDentry.dirMu.Unlock() - - if err := virtfs.PrepareRenameDentry(mntns, srcVFSD, dstVFSD); err != nil { - return err - } - srcDirInode := srcDirDentry.inode - replaced, err := srcDirInode.Rename(ctx, srcVFSD.Name(), pc, srcVFSD, dstDirVFSD) - if err != nil { - virtfs.AbortRenameDentry(srcVFSD, dstVFSD) - return err - } - virtfs.CommitRenameReplaceDentry(srcVFSD, dstDirVFSD, pc, replaced) - return nil -} - -// RmdirAt implements vfs.FilesystemImpl.RmdirAt. -func (fs *Filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error { - fs.mu.Lock() - defer fs.mu.Unlock() - vfsd, inode, err := fs.walkExistingLocked(ctx, rp) - fs.processDeferredDecRefsLocked() - if err != nil { - return err - } - if err := rp.Mount().CheckBeginWrite(); err != nil { - return err - } - defer rp.Mount().EndWrite() - if err := checkDeleteLocked(rp, vfsd); err != nil { - return err - } - if !vfsd.Impl().(*Dentry).isDir() { - return syserror.ENOTDIR - } - if inode.HasChildren() { - return syserror.ENOTEMPTY - } - virtfs := rp.VirtualFilesystem() - parentDentry := vfsd.Parent().Impl().(*Dentry) - parentDentry.dirMu.Lock() - defer parentDentry.dirMu.Unlock() - if err := virtfs.PrepareDeleteDentry(vfs.MountNamespaceFromContext(ctx), vfsd); err != nil { - return err - } - if err := parentDentry.inode.RmDir(ctx, rp.Component(), vfsd); err != nil { - virtfs.AbortDeleteDentry(vfsd) - return err - } - virtfs.CommitDeleteDentry(vfsd) - return nil -} - -// SetStatAt implements vfs.FilesystemImpl.SetStatAt. -func (fs *Filesystem) SetStatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.SetStatOptions) error { - fs.mu.RLock() - _, inode, err := fs.walkExistingLocked(ctx, rp) - fs.mu.RUnlock() - fs.processDeferredDecRefs() - if err != nil { - return err - } - if opts.Stat.Mask == 0 { - return nil - } - return inode.SetStat(fs.VFSFilesystem(), opts) -} - -// StatAt implements vfs.FilesystemImpl.StatAt. -func (fs *Filesystem) StatAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.StatOptions) (linux.Statx, error) { - fs.mu.RLock() - _, inode, err := fs.walkExistingLocked(ctx, rp) - fs.mu.RUnlock() - fs.processDeferredDecRefs() - if err != nil { - return linux.Statx{}, err - } - return inode.Stat(fs.VFSFilesystem()), nil -} - -// StatFSAt implements vfs.FilesystemImpl.StatFSAt. -func (fs *Filesystem) StatFSAt(ctx context.Context, rp *vfs.ResolvingPath) (linux.Statfs, error) { - fs.mu.RLock() - _, _, err := fs.walkExistingLocked(ctx, rp) - fs.mu.RUnlock() - fs.processDeferredDecRefs() - if err != nil { - return linux.Statfs{}, err - } - // TODO: actually implement statfs - return linux.Statfs{}, syserror.ENOSYS -} - -// SymlinkAt implements vfs.FilesystemImpl.SymlinkAt. -func (fs *Filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, target string) error { - if rp.Done() { - return syserror.EEXIST - } - fs.mu.Lock() - defer fs.mu.Unlock() - parentVFSD, parentInode, err := fs.walkParentDirLocked(ctx, rp) - fs.processDeferredDecRefsLocked() - if err != nil { - return err - } - pc, err := checkCreateLocked(rp, parentVFSD, parentInode) - if err != nil { - return err - } - if err := rp.Mount().CheckBeginWrite(); err != nil { - return err - } - defer rp.Mount().EndWrite() - child, err := parentInode.NewSymlink(ctx, pc, target) - if err != nil { - return err - } - parentVFSD.Impl().(*Dentry).InsertChild(pc, child) - return nil -} - -// UnlinkAt implements vfs.FilesystemImpl.UnlinkAt. -func (fs *Filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error { - fs.mu.Lock() - defer fs.mu.Unlock() - vfsd, _, err := fs.walkExistingLocked(ctx, rp) - fs.processDeferredDecRefsLocked() - if err != nil { - return err - } - if err := rp.Mount().CheckBeginWrite(); err != nil { - return err - } - defer rp.Mount().EndWrite() - if err := checkDeleteLocked(rp, vfsd); err != nil { - return err - } - if vfsd.Impl().(*Dentry).isDir() { - return syserror.EISDIR - } - virtfs := rp.VirtualFilesystem() - parentDentry := vfsd.Parent().Impl().(*Dentry) - parentDentry.dirMu.Lock() - defer parentDentry.dirMu.Unlock() - if err := virtfs.PrepareDeleteDentry(vfs.MountNamespaceFromContext(ctx), vfsd); err != nil { - return err - } - if err := parentDentry.inode.Unlink(ctx, rp.Component(), vfsd); err != nil { - virtfs.AbortDeleteDentry(vfsd) - return err - } - virtfs.CommitDeleteDentry(vfsd) - return nil -} - -// PrependPath implements vfs.FilesystemImpl.PrependPath. -func (fs *Filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDentry, b *fspath.Builder) error { - fs.mu.RLock() - defer fs.mu.RUnlock() - return vfs.GenericPrependPath(vfsroot, vd, b) -} |