diff options
Diffstat (limited to 'pkg')
| -rwxr-xr-x | pkg/fspath/fspath.go | 24 | ||||
| -rwxr-xr-x | pkg/sentry/vfs/dentry.go | 29 | ||||
| -rwxr-xr-x | pkg/sentry/vfs/file_description.go | 19 | ||||
| -rwxr-xr-x | pkg/sentry/vfs/filesystem.go | 251 | ||||
| -rwxr-xr-x | pkg/sentry/vfs/options.go | 3 | ||||
| -rwxr-xr-x | pkg/sentry/vfs/resolving_path.go | 46 | ||||
| -rwxr-xr-x | pkg/sentry/vfs/testutil.go | 7 | ||||
| -rwxr-xr-x | pkg/sentry/vfs/vfs.go | 259 | ||||
| -rw-r--r-- | pkg/syserror/syserror.go | 1 |
9 files changed, 512 insertions, 127 deletions
diff --git a/pkg/fspath/fspath.go b/pkg/fspath/fspath.go index f68752560..9fb3fee24 100755 --- a/pkg/fspath/fspath.go +++ b/pkg/fspath/fspath.go @@ -18,19 +18,17 @@ package fspath import ( "strings" - - "gvisor.dev/gvisor/pkg/syserror" ) const pathSep = '/' -// Parse parses a pathname as described by path_resolution(7). -func Parse(pathname string) (Path, error) { +// Parse parses a pathname as described by path_resolution(7), except that +// empty pathnames will be parsed successfully to a Path for which +// Path.Absolute == Path.Dir == Path.HasComponents() == false. (This is +// necessary to support AT_EMPTY_PATH.) +func Parse(pathname string) Path { if len(pathname) == 0 { - // "... POSIX decrees that an empty pathname must not be resolved - // successfully. Linux returns ENOENT in this case." - - // path_resolution(7) - return Path{}, syserror.ENOENT + return Path{} } // Skip leading path separators. i := 0 @@ -41,7 +39,7 @@ func Parse(pathname string) (Path, error) { return Path{ Absolute: true, Dir: true, - }, nil + } } } // Skip trailing path separators. This is required by Iterator.Next. This @@ -64,7 +62,7 @@ func Parse(pathname string) (Path, error) { }, Absolute: i != 0, Dir: j != len(pathname)-1, - }, nil + } } // Path contains the information contained in a pathname string. @@ -111,6 +109,12 @@ func (p Path) String() string { return b.String() } +// HasComponents returns true if p contains a non-zero number of path +// components. +func (p Path) HasComponents() bool { + return p.Begin.Ok() +} + // An Iterator represents either a path component in a Path or a terminal // iterator indicating that the end of the path has been reached. // diff --git a/pkg/sentry/vfs/dentry.go b/pkg/sentry/vfs/dentry.go index 6209eb053..1bc9c4a38 100755 --- a/pkg/sentry/vfs/dentry.go +++ b/pkg/sentry/vfs/dentry.go @@ -234,6 +234,18 @@ func (d *Dentry) InsertChild(child *Dentry, name string) { child.name = name } +// IsAncestorOf returns true if d is an ancestor of d2; that is, d is either +// d2's parent or an ancestor of d2's parent. +func (d *Dentry) IsAncestorOf(d2 *Dentry) bool { + for d2.parent != nil { + if d2.parent == d { + return true + } + d2 = d2.parent + } + return false +} + // PrepareDeleteDentry must be called before attempting to delete the file // represented by d. If PrepareDeleteDentry succeeds, the caller must call // AbortDeleteDentry or CommitDeleteDentry depending on the deletion's outcome. @@ -283,21 +295,6 @@ func (vfs *VirtualFilesystem) CommitDeleteDentry(d *Dentry) { } } -// DeleteDentry combines PrepareDeleteDentry and CommitDeleteDentry, as -// appropriate for in-memory filesystems that don't need to ensure that some -// external state change succeeds before committing the deletion. -// -// DeleteDentry is a mutator of d and d.Parent(). -// -// Preconditions: d is a child Dentry. -func (vfs *VirtualFilesystem) DeleteDentry(mntns *MountNamespace, d *Dentry) error { - if err := vfs.PrepareDeleteDentry(mntns, d); err != nil { - return err - } - vfs.CommitDeleteDentry(d) - return nil -} - // ForceDeleteDentry causes d to become disowned. It should only be used in // cases where VFS has no ability to stop the deletion (e.g. d represents the // local state of a file on a remote filesystem on which the file has already @@ -326,7 +323,7 @@ func (vfs *VirtualFilesystem) ForceDeleteDentry(d *Dentry) { // CommitRenameExchangeDentry depending on the rename's outcome. // // Preconditions: from is a child Dentry. If to is not nil, it must be a child -// Dentry from the same Filesystem. +// Dentry from the same Filesystem. from != to. func (vfs *VirtualFilesystem) PrepareRenameDentry(mntns *MountNamespace, from, to *Dentry) error { if checkInvariants { if from.parent == nil { diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go index df03886c3..0b053201a 100755 --- a/pkg/sentry/vfs/file_description.go +++ b/pkg/sentry/vfs/file_description.go @@ -192,6 +192,8 @@ func (fd *FileDescription) Impl() FileDescriptionImpl { // be interpreted as IDs in the root UserNamespace (i.e. as auth.KUID and // auth.KGID respectively). // +// All methods may return errors not specified. +// // FileDescriptionImpl is analogous to Linux's struct file_operations. type FileDescriptionImpl interface { // Release is called when the associated FileDescription reaches zero @@ -220,6 +222,10 @@ type FileDescriptionImpl interface { // PRead reads from the file into dst, starting at the given offset, and // returns the number of bytes read. PRead is permitted to return partial // reads with a nil error. + // + // Errors: + // + // - If opts.Flags specifies unsupported options, PRead returns EOPNOTSUPP. PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts ReadOptions) (int64, error) // Read is similar to PRead, but does not specify an offset. @@ -229,6 +235,10 @@ type FileDescriptionImpl interface { // the number of bytes read; note that POSIX 2.9.7 "Thread Interactions // with Regular File Operations" requires that all operations that may // mutate the FileDescription offset are serialized. + // + // Errors: + // + // - If opts.Flags specifies unsupported options, Read returns EOPNOTSUPP. Read(ctx context.Context, dst usermem.IOSequence, opts ReadOptions) (int64, error) // PWrite writes src to the file, starting at the given offset, and returns @@ -238,6 +248,11 @@ type FileDescriptionImpl interface { // As in Linux (but not POSIX), if O_APPEND is in effect for the // FileDescription, PWrite should ignore the offset and append data to the // end of the file. + // + // Errors: + // + // - If opts.Flags specifies unsupported options, PWrite returns + // EOPNOTSUPP. PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts WriteOptions) (int64, error) // Write is similar to PWrite, but does not specify an offset, which is @@ -247,6 +262,10 @@ type FileDescriptionImpl interface { // PWrite that uses a FileDescription offset, to make it possible for // remote filesystems to implement O_APPEND correctly (i.e. atomically with // respect to writers outside the scope of VFS). + // + // Errors: + // + // - If opts.Flags specifies unsupported options, Write returns EOPNOTSUPP. Write(ctx context.Context, src usermem.IOSequence, opts WriteOptions) (int64, error) // IterDirents invokes cb on each entry in the directory represented by the diff --git a/pkg/sentry/vfs/filesystem.go b/pkg/sentry/vfs/filesystem.go index b766614e7..89bd58864 100755 --- a/pkg/sentry/vfs/filesystem.go +++ b/pkg/sentry/vfs/filesystem.go @@ -108,6 +108,24 @@ func (fs *Filesystem) DecRef() { // (responsible for actually implementing the operation) isn't known until path // resolution is complete. // +// Unless otherwise specified, FilesystemImpl methods are responsible for +// performing permission checks. In many cases, vfs package functions in +// permissions.go may be used to help perform these checks. +// +// When multiple specified error conditions apply to a given method call, the +// implementation may return any applicable errno unless otherwise specified, +// but returning the earliest error specified is preferable to maximize +// compatibility with Linux. +// +// All methods may return errors not specified, notably including: +// +// - ENOENT if a required path component does not exist. +// +// - ENOTDIR if an intermediate path component is not a directory. +// +// - Errors from vfs-package functions (ResolvingPath.Resolve*(), +// Mount.CheckBeginWrite(), permission-checking functions, etc.) +// // For all methods that take or return linux.Statx, Statx.Uid and Statx.Gid // should be interpreted as IDs in the root UserNamespace (i.e. as auth.KUID // and auth.KGID respectively). @@ -130,46 +148,223 @@ type FilesystemImpl interface { // GetDentryAt does not correspond directly to a Linux syscall; it is used // in the implementation of: // - // - Syscalls that need to resolve two paths: rename(), renameat(), - // renameat2(), link(), linkat(). + // - Syscalls that need to resolve two paths: link(), linkat(). // // - Syscalls that need to refer to a filesystem position outside the // context of a file description: chdir(), fchdir(), chroot(), mount(), // umount(). GetDentryAt(ctx context.Context, rp *ResolvingPath, opts GetDentryOptions) (*Dentry, error) + // GetParentDentryAt returns a Dentry representing the directory at the + // second-to-last path component in rp. (Note that, despite the name, this + // is not necessarily the parent directory of the file at rp, since the + // last path component in rp may be "." or "..".) A reference is taken on + // the returned Dentry. + // + // GetParentDentryAt does not correspond directly to a Linux syscall; it is + // used in the implementation of the rename() family of syscalls, which + // must resolve the parent directories of two paths. + // + // Preconditions: !rp.Done(). + // + // Postconditions: If GetParentDentryAt returns a nil error, then + // rp.Final(). If GetParentDentryAt returns an error returned by + // ResolvingPath.Resolve*(), then !rp.Done(). + GetParentDentryAt(ctx context.Context, rp *ResolvingPath) (*Dentry, error) + // LinkAt creates a hard link at rp representing the same file as vd. It // does not take ownership of references on vd. // - // The implementation is responsible for checking that vd.Mount() == - // rp.Mount(), and that vd does not represent a directory. + // Errors: + // + // - If the last path component in rp is "." or "..", LinkAt returns + // EEXIST. + // + // - If a file already exists at rp, LinkAt returns EEXIST. + // + // - If rp.MustBeDir(), LinkAt returns ENOENT. + // + // - If the directory in which the link would be created has been removed + // by RmdirAt or RenameAt, LinkAt returns ENOENT. + // + // - If rp.Mount != vd.Mount(), LinkAt returns EXDEV. + // + // - If vd represents a directory, LinkAt returns EPERM. + // + // - If vd represents a file for which all existing links have been + // removed, or a file created by open(O_TMPFILE|O_EXCL), LinkAt returns + // ENOENT. Equivalently, if vd represents a file with a link count of 0 not + // created by open(O_TMPFILE) without O_EXCL, LinkAt returns ENOENT. + // + // Preconditions: !rp.Done(). For the final path component in rp, + // !rp.ShouldFollowSymlink(). + // + // Postconditions: If LinkAt returns an error returned by + // ResolvingPath.Resolve*(), then !rp.Done(). LinkAt(ctx context.Context, rp *ResolvingPath, vd VirtualDentry) error // MkdirAt creates a directory at rp. + // + // Errors: + // + // - If the last path component in rp is "." or "..", MkdirAt returns + // EEXIST. + // + // - If a file already exists at rp, MkdirAt returns EEXIST. + // + // - If the directory in which the new directory would be created has been + // removed by RmdirAt or RenameAt, MkdirAt returns ENOENT. + // + // Preconditions: !rp.Done(). For the final path component in rp, + // !rp.ShouldFollowSymlink(). + // + // Postconditions: If MkdirAt returns an error returned by + // ResolvingPath.Resolve*(), then !rp.Done(). MkdirAt(ctx context.Context, rp *ResolvingPath, opts MkdirOptions) error // MknodAt creates a regular file, device special file, or named pipe at // rp. + // + // Errors: + // + // - If the last path component in rp is "." or "..", MknodAt returns + // EEXIST. + // + // - If a file already exists at rp, MknodAt returns EEXIST. + // + // - If rp.MustBeDir(), MknodAt returns ENOENT. + // + // - If the directory in which the file would be created has been removed + // by RmdirAt or RenameAt, MknodAt returns ENOENT. + // + // Preconditions: !rp.Done(). For the final path component in rp, + // !rp.ShouldFollowSymlink(). + // + // Postconditions: If MknodAt returns an error returned by + // ResolvingPath.Resolve*(), then !rp.Done(). MknodAt(ctx context.Context, rp *ResolvingPath, opts MknodOptions) error // OpenAt returns an FileDescription providing access to the file at rp. A // reference is taken on the returned FileDescription. + // + // Errors: + // + // - If opts.Flags specifies O_TMPFILE and this feature is unsupported by + // the implementation, OpenAt returns EOPNOTSUPP. (All other unsupported + // features are silently ignored, consistently with Linux's open*(2).) OpenAt(ctx context.Context, rp *ResolvingPath, opts OpenOptions) (*FileDescription, error) // ReadlinkAt returns the target of the symbolic link at rp. + // + // Errors: + // + // - If the file at rp is not a symbolic link, ReadlinkAt returns EINVAL. ReadlinkAt(ctx context.Context, rp *ResolvingPath) (string, error) - // RenameAt renames the Dentry represented by vd to rp. It does not take - // ownership of references on vd. + // RenameAt renames the file named oldName in directory oldParentVD to rp. + // It does not take ownership of references on oldParentVD. + // + // Errors [1]: + // + // - If opts.Flags specifies unsupported options, RenameAt returns EINVAL. + // + // - If the last path component in rp is "." or "..", and opts.Flags + // contains RENAME_NOREPLACE, RenameAt returns EEXIST. + // + // - If the last path component in rp is "." or "..", and opts.Flags does + // not contain RENAME_NOREPLACE, RenameAt returns EBUSY. + // + // - If rp.Mount != oldParentVD.Mount(), RenameAt returns EXDEV. // - // The implementation is responsible for checking that vd.Mount() == - // rp.Mount(). - RenameAt(ctx context.Context, rp *ResolvingPath, vd VirtualDentry, opts RenameOptions) error + // - If the renamed file is not a directory, and opts.MustBeDir is true, + // RenameAt returns ENOTDIR. + // + // - If renaming would replace an existing file and opts.Flags contains + // RENAME_NOREPLACE, RenameAt returns EEXIST. + // + // - If there is no existing file at rp and opts.Flags contains + // RENAME_EXCHANGE, RenameAt returns ENOENT. + // + // - If there is an existing non-directory file at rp, and rp.MustBeDir() + // is true, RenameAt returns ENOTDIR. + // + // - If the renamed file is not a directory, opts.Flags does not contain + // RENAME_EXCHANGE, and rp.MustBeDir() is true, RenameAt returns ENOTDIR. + // (This check is not subsumed by the check for directory replacement below + // since it applies even if there is no file to replace.) + // + // - If the renamed file is a directory, and the new parent directory of + // the renamed file is either the renamed directory or a descendant + // subdirectory of the renamed directory, RenameAt returns EINVAL. + // + // - If renaming would exchange the renamed file with an ancestor directory + // of the renamed file, RenameAt returns EINVAL. + // + // - If renaming would replace an ancestor directory of the renamed file, + // RenameAt returns ENOTEMPTY. (This check would be subsumed by the + // non-empty directory check below; however, this check takes place before + // the self-rename check.) + // + // - If the renamed file would replace or exchange with itself (i.e. the + // source and destination paths resolve to the same file), RenameAt returns + // nil, skipping the checks described below. + // + // - If the source or destination directory is not writable by the provider + // of rp.Credentials(), RenameAt returns EACCES. + // + // - If the renamed file is a directory, and renaming would replace a + // non-directory file, RenameAt returns ENOTDIR. + // + // - If the renamed file is not a directory, and renaming would replace a + // directory, RenameAt returns EISDIR. + // + // - If the new parent directory of the renamed file has been removed by + // RmdirAt or a preceding call to RenameAt, RenameAt returns ENOENT. + // + // - If the renamed file is a directory, it is not writable by the + // provider of rp.Credentials(), and the source and destination parent + // directories are different, RenameAt returns EACCES. (This is nominally + // required to change the ".." entry in the renamed directory.) + // + // - If renaming would replace a non-empty directory, RenameAt returns + // ENOTEMPTY. + // + // Preconditions: !rp.Done(). For the final path component in rp, + // !rp.ShouldFollowSymlink(). oldName is not "." or "..". + // + // Postconditions: If RenameAt returns an error returned by + // ResolvingPath.Resolve*(), then !rp.Done(). + // + // [1] "The worst of all namespace operations - renaming directory. + // "Perverted" doesn't even start to describe it. Somebody in UCB had a + // heck of a trip..." - fs/namei.c:vfs_rename() + RenameAt(ctx context.Context, rp *ResolvingPath, oldParentVD VirtualDentry, oldName string, opts RenameOptions) error // RmdirAt removes the directory at rp. + // + // Errors: + // + // - If the last path component in rp is ".", RmdirAt returns EINVAL. + // + // - If the last path component in rp is "..", RmdirAt returns ENOTEMPTY. + // + // - If no file exists at rp, RmdirAt returns ENOENT. + // + // - If the file at rp exists but is not a directory, RmdirAt returns + // ENOTDIR. + // + // Preconditions: !rp.Done(). For the final path component in rp, + // !rp.ShouldFollowSymlink(). + // + // Postconditions: If RmdirAt returns an error returned by + // ResolvingPath.Resolve*(), then !rp.Done(). RmdirAt(ctx context.Context, rp *ResolvingPath) error // SetStatAt updates metadata for the file at the given path. + // + // Errors: + // + // - If opts specifies unsupported options, SetStatAt returns EINVAL. SetStatAt(ctx context.Context, rp *ResolvingPath, opts SetStatOptions) error // StatAt returns metadata for the file at rp. @@ -181,9 +376,45 @@ type FilesystemImpl interface { StatFSAt(ctx context.Context, rp *ResolvingPath) (linux.Statfs, error) // SymlinkAt creates a symbolic link at rp referring to the given target. + // + // Errors: + // + // - If the last path component in rp is "." or "..", SymlinkAt returns + // EEXIST. + // + // - If a file already exists at rp, SymlinkAt returns EEXIST. + // + // - If rp.MustBeDir(), SymlinkAt returns ENOENT. + // + // - If the directory in which the symbolic link would be created has been + // removed by RmdirAt or RenameAt, SymlinkAt returns ENOENT. + // + // Preconditions: !rp.Done(). For the final path component in rp, + // !rp.ShouldFollowSymlink(). + // + // Postconditions: If SymlinkAt returns an error returned by + // ResolvingPath.Resolve*(), then !rp.Done(). SymlinkAt(ctx context.Context, rp *ResolvingPath, target string) error - // UnlinkAt removes the non-directory file at rp. + // UnlinkAt removes the file at rp. + // + // Errors: + // + // - If the last path component in rp is "." or "..", UnlinkAt returns + // EISDIR. + // + // - If no file exists at rp, UnlinkAt returns ENOENT. + // + // - If rp.MustBeDir(), and the file at rp exists and is not a directory, + // UnlinkAt returns ENOTDIR. + // + // - If the file at rp exists but is a directory, UnlinkAt returns EISDIR. + // + // Preconditions: !rp.Done(). For the final path component in rp, + // !rp.ShouldFollowSymlink(). + // + // Postconditions: If UnlinkAt returns an error returned by + // ResolvingPath.Resolve*(), then !rp.Done(). UnlinkAt(ctx context.Context, rp *ResolvingPath) error // ListxattrAt returns all extended attribute names for the file at rp. diff --git a/pkg/sentry/vfs/options.go b/pkg/sentry/vfs/options.go index 97ee4a446..87d2b0d1c 100755 --- a/pkg/sentry/vfs/options.go +++ b/pkg/sentry/vfs/options.go @@ -83,6 +83,9 @@ type ReadOptions struct { 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(), diff --git a/pkg/sentry/vfs/resolving_path.go b/pkg/sentry/vfs/resolving_path.go index d580fd39e..f0641d314 100755 --- a/pkg/sentry/vfs/resolving_path.go +++ b/pkg/sentry/vfs/resolving_path.go @@ -112,30 +112,26 @@ var resolvingPathPool = sync.Pool{ }, } -func (vfs *VirtualFilesystem) getResolvingPath(creds *auth.Credentials, pop *PathOperation) (*ResolvingPath, error) { - path, err := fspath.Parse(pop.Pathname) - if err != nil { - return nil, err - } +func (vfs *VirtualFilesystem) getResolvingPath(creds *auth.Credentials, pop *PathOperation) *ResolvingPath { rp := resolvingPathPool.Get().(*ResolvingPath) rp.vfs = vfs rp.root = pop.Root rp.mount = pop.Start.mount rp.start = pop.Start.dentry - rp.pit = path.Begin + rp.pit = pop.Path.Begin rp.flags = 0 if pop.FollowFinalSymlink { rp.flags |= rpflagsFollowFinalSymlink } - rp.mustBeDir = path.Dir - rp.mustBeDirOrig = path.Dir + rp.mustBeDir = pop.Path.Dir + rp.mustBeDirOrig = pop.Path.Dir rp.symlinks = 0 rp.curPart = 0 rp.numOrigParts = 1 rp.creds = creds - rp.parts[0] = path.Begin - rp.origParts[0] = path.Begin - return rp, nil + rp.parts[0] = pop.Path.Begin + rp.origParts[0] = pop.Path.Begin + return rp } func (vfs *VirtualFilesystem) putResolvingPath(rp *ResolvingPath) { @@ -345,29 +341,34 @@ func (rp *ResolvingPath) ShouldFollowSymlink() bool { // symlink target and returns nil. Otherwise it returns a non-nil error. // // Preconditions: !rp.Done(). +// +// Postconditions: If HandleSymlink returns a nil error, then !rp.Done(). func (rp *ResolvingPath) HandleSymlink(target string) error { if rp.symlinks >= linux.MaxSymlinkTraversals { return syserror.ELOOP } - targetPath, err := fspath.Parse(target) - if err != nil { - return err + if len(target) == 0 { + return syserror.ENOENT } rp.symlinks++ + targetPath := fspath.Parse(target) if targetPath.Absolute { rp.absSymlinkTarget = targetPath return resolveAbsSymlinkError{} } - if !targetPath.Begin.Ok() { - panic(fmt.Sprintf("symbolic link has non-empty target %q that is both relative and has no path components?", target)) - } // Consume the path component that represented the symlink. rp.Advance() // Prepend the symlink target to the relative path. + if checkInvariants { + if !targetPath.HasComponents() { + panic(fmt.Sprintf("non-empty pathname %q parsed to relative path with no components", target)) + } + } rp.relpathPrepend(targetPath) return nil } +// Preconditions: path.HasComponents(). func (rp *ResolvingPath) relpathPrepend(path fspath.Path) { if rp.pit.Ok() { rp.parts[rp.curPart] = rp.pit @@ -467,6 +468,17 @@ func (rp *ResolvingPath) handleError(err error) bool { } } +// canHandleError returns true if err is an error returned by rp.Resolve*() +// that rp.handleError() may attempt to handle. +func (rp *ResolvingPath) canHandleError(err error) bool { + switch err.(type) { + case resolveMountRootOrJumpError, resolveMountPointError, resolveAbsSymlinkError: + return true + default: + return false + } +} + // MustBeDir returns true if the file traversed by rp must be a directory. func (rp *ResolvingPath) MustBeDir() bool { return rp.mustBeDir diff --git a/pkg/sentry/vfs/testutil.go b/pkg/sentry/vfs/testutil.go index d94117bce..ee5c8b9e2 100755 --- a/pkg/sentry/vfs/testutil.go +++ b/pkg/sentry/vfs/testutil.go @@ -57,6 +57,11 @@ func (fs *FDTestFilesystem) GetDentryAt(ctx context.Context, rp *ResolvingPath, return nil, syserror.EPERM } +// GetParentDentryAt implements FilesystemImpl.GetParentDentryAt. +func (fs *FDTestFilesystem) GetParentDentryAt(ctx context.Context, rp *ResolvingPath) (*Dentry, error) { + return nil, syserror.EPERM +} + // LinkAt implements FilesystemImpl.LinkAt. func (fs *FDTestFilesystem) LinkAt(ctx context.Context, rp *ResolvingPath, vd VirtualDentry) error { return syserror.EPERM @@ -83,7 +88,7 @@ func (fs *FDTestFilesystem) ReadlinkAt(ctx context.Context, rp *ResolvingPath) ( } // RenameAt implements FilesystemImpl.RenameAt. -func (fs *FDTestFilesystem) RenameAt(ctx context.Context, rp *ResolvingPath, vd VirtualDentry, opts RenameOptions) error { +func (fs *FDTestFilesystem) RenameAt(ctx context.Context, rp *ResolvingPath, oldParentVD VirtualDentry, oldName string, opts RenameOptions) error { return syserror.EPERM } diff --git a/pkg/sentry/vfs/vfs.go b/pkg/sentry/vfs/vfs.go index e60898d7c..3e4df8558 100755 --- a/pkg/sentry/vfs/vfs.go +++ b/pkg/sentry/vfs/vfs.go @@ -28,9 +28,11 @@ package vfs import ( + "fmt" "sync" "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/syserror" @@ -111,11 +113,11 @@ type PathOperation struct { // are borrowed from the provider of the PathOperation (i.e. the caller of // the VFS method to which the PathOperation was passed). // - // Invariants: Start.Ok(). If Pathname.Absolute, then Start == Root. + // Invariants: Start.Ok(). If Path.Absolute, then Start == Root. Start VirtualDentry // Path is the pathname traversed by this operation. - Pathname string + Path fspath.Path // If FollowFinalSymlink is true, and the Dentry traversed by the final // path component represents a symbolic link, the symbolic link should be @@ -126,10 +128,7 @@ type PathOperation struct { // GetDentryAt returns a VirtualDentry representing the given path, at which a // file must exist. A reference is taken on the returned VirtualDentry. func (vfs *VirtualFilesystem) GetDentryAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *GetDentryOptions) (VirtualDentry, error) { - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return VirtualDentry{}, err - } + rp := vfs.getResolvingPath(creds, pop) for { d, err := rp.mount.fs.impl.GetDentryAt(ctx, rp, *opts) if err == nil { @@ -148,6 +147,33 @@ func (vfs *VirtualFilesystem) GetDentryAt(ctx context.Context, creds *auth.Crede } } +// Preconditions: pop.Path.Begin.Ok(). +func (vfs *VirtualFilesystem) getParentDirAndName(ctx context.Context, creds *auth.Credentials, pop *PathOperation) (VirtualDentry, string, error) { + rp := vfs.getResolvingPath(creds, pop) + for { + parent, err := rp.mount.fs.impl.GetParentDentryAt(ctx, rp) + if err == nil { + parentVD := VirtualDentry{ + mount: rp.mount, + dentry: parent, + } + rp.mount.IncRef() + name := rp.Component() + vfs.putResolvingPath(rp) + return parentVD, name, nil + } + if checkInvariants { + if rp.canHandleError(err) && rp.Done() { + panic(fmt.Sprintf("%T.GetParentDentryAt() consumed all path components and returned %T", rp.mount.fs.impl, err)) + } + } + if !rp.handleError(err) { + vfs.putResolvingPath(rp) + return VirtualDentry{}, "", err + } + } +} + // LinkAt creates a hard link at newpop representing the existing file at // oldpop. func (vfs *VirtualFilesystem) LinkAt(ctx context.Context, creds *auth.Credentials, oldpop, newpop *PathOperation) error { @@ -155,21 +181,36 @@ func (vfs *VirtualFilesystem) LinkAt(ctx context.Context, creds *auth.Credential if err != nil { return err } - rp, err := vfs.getResolvingPath(creds, newpop) - if err != nil { + + if !newpop.Path.Begin.Ok() { oldVD.DecRef() - return err + if newpop.Path.Absolute { + return syserror.EEXIST + } + return syserror.ENOENT } + if newpop.FollowFinalSymlink { + oldVD.DecRef() + ctx.Warningf("VirtualFilesystem.LinkAt: file creation paths can't follow final symlink") + return syserror.EINVAL + } + + rp := vfs.getResolvingPath(creds, newpop) for { err := rp.mount.fs.impl.LinkAt(ctx, rp, oldVD) if err == nil { - oldVD.DecRef() vfs.putResolvingPath(rp) + oldVD.DecRef() return nil } + if checkInvariants { + if rp.canHandleError(err) && rp.Done() { + panic(fmt.Sprintf("%T.LinkAt() consumed all path components and returned %T", rp.mount.fs.impl, err)) + } + } if !rp.handleError(err) { - oldVD.DecRef() vfs.putResolvingPath(rp) + oldVD.DecRef() return err } } @@ -177,19 +218,32 @@ func (vfs *VirtualFilesystem) LinkAt(ctx context.Context, creds *auth.Credential // MkdirAt creates a directory at the given path. func (vfs *VirtualFilesystem) MkdirAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *MkdirOptions) error { + if !pop.Path.Begin.Ok() { + if pop.Path.Absolute { + return syserror.EEXIST + } + return syserror.ENOENT + } + if pop.FollowFinalSymlink { + ctx.Warningf("VirtualFilesystem.MkdirAt: file creation paths can't follow final symlink") + return syserror.EINVAL + } // "Under Linux, apart from the permission bits, the S_ISVTX mode bit is // also honored." - mkdir(2) opts.Mode &= 0777 | linux.S_ISVTX - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return err - } + + rp := vfs.getResolvingPath(creds, pop) for { err := rp.mount.fs.impl.MkdirAt(ctx, rp, *opts) if err == nil { vfs.putResolvingPath(rp) return nil } + if checkInvariants { + if rp.canHandleError(err) && rp.Done() { + panic(fmt.Sprintf("%T.MkdirAt() consumed all path components and returned %T", rp.mount.fs.impl, err)) + } + } if !rp.handleError(err) { vfs.putResolvingPath(rp) return err @@ -200,16 +254,29 @@ func (vfs *VirtualFilesystem) MkdirAt(ctx context.Context, creds *auth.Credentia // MknodAt creates a file of the given mode at the given path. It returns an // error from the syserror package. func (vfs *VirtualFilesystem) MknodAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *MknodOptions) error { - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return nil + if !pop.Path.Begin.Ok() { + if pop.Path.Absolute { + return syserror.EEXIST + } + return syserror.ENOENT + } + if pop.FollowFinalSymlink { + ctx.Warningf("VirtualFilesystem.MknodAt: file creation paths can't follow final symlink") + return syserror.EINVAL } + + rp := vfs.getResolvingPath(creds, pop) for { - if err = rp.mount.fs.impl.MknodAt(ctx, rp, *opts); err == nil { + err := rp.mount.fs.impl.MknodAt(ctx, rp, *opts) + if err != nil { vfs.putResolvingPath(rp) return nil } - // Handle mount traversals. + if checkInvariants { + if rp.canHandleError(err) && rp.Done() { + panic(fmt.Sprintf("%T.MknodAt() consumed all path components and returned %T", rp.mount.fs.impl, err)) + } + } if !rp.handleError(err) { vfs.putResolvingPath(rp) return err @@ -259,10 +326,7 @@ func (vfs *VirtualFilesystem) OpenAt(ctx context.Context, creds *auth.Credential if opts.Flags&linux.O_NOFOLLOW != 0 { pop.FollowFinalSymlink = false } - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return nil, err - } + rp := vfs.getResolvingPath(creds, pop) if opts.Flags&linux.O_DIRECTORY != 0 { rp.mustBeDir = true rp.mustBeDirOrig = true @@ -282,10 +346,7 @@ func (vfs *VirtualFilesystem) OpenAt(ctx context.Context, creds *auth.Credential // ReadlinkAt returns the target of the symbolic link at the given path. func (vfs *VirtualFilesystem) ReadlinkAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation) (string, error) { - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return "", err - } + rp := vfs.getResolvingPath(creds, pop) for { target, err := rp.mount.fs.impl.ReadlinkAt(ctx, rp) if err == nil { @@ -301,25 +362,59 @@ func (vfs *VirtualFilesystem) ReadlinkAt(ctx context.Context, creds *auth.Creden // RenameAt renames the file at oldpop to newpop. func (vfs *VirtualFilesystem) RenameAt(ctx context.Context, creds *auth.Credentials, oldpop, newpop *PathOperation, opts *RenameOptions) error { - oldVD, err := vfs.GetDentryAt(ctx, creds, oldpop, &GetDentryOptions{}) - if err != nil { - return err + if !oldpop.Path.Begin.Ok() { + if oldpop.Path.Absolute { + return syserror.EBUSY + } + return syserror.ENOENT } - rp, err := vfs.getResolvingPath(creds, newpop) + if oldpop.FollowFinalSymlink { + ctx.Warningf("VirtualFilesystem.RenameAt: source path can't follow final symlink") + return syserror.EINVAL + } + + oldParentVD, oldName, err := vfs.getParentDirAndName(ctx, creds, oldpop) if err != nil { - oldVD.DecRef() return err } + if oldName == "." || oldName == ".." { + oldParentVD.DecRef() + return syserror.EBUSY + } + + if !newpop.Path.Begin.Ok() { + oldParentVD.DecRef() + if newpop.Path.Absolute { + return syserror.EBUSY + } + return syserror.ENOENT + } + if newpop.FollowFinalSymlink { + oldParentVD.DecRef() + ctx.Warningf("VirtualFilesystem.RenameAt: destination path can't follow final symlink") + return syserror.EINVAL + } + + rp := vfs.getResolvingPath(creds, newpop) + renameOpts := *opts + if oldpop.Path.Dir { + renameOpts.MustBeDir = true + } for { - err := rp.mount.fs.impl.RenameAt(ctx, rp, oldVD, *opts) + err := rp.mount.fs.impl.RenameAt(ctx, rp, oldParentVD, oldName, renameOpts) if err == nil { - oldVD.DecRef() vfs.putResolvingPath(rp) + oldParentVD.DecRef() return nil } + if checkInvariants { + if rp.canHandleError(err) && rp.Done() { + panic(fmt.Sprintf("%T.RenameAt() consumed all path components and returned %T", rp.mount.fs.impl, err)) + } + } if !rp.handleError(err) { - oldVD.DecRef() vfs.putResolvingPath(rp) + oldParentVD.DecRef() return err } } @@ -327,16 +422,29 @@ func (vfs *VirtualFilesystem) RenameAt(ctx context.Context, creds *auth.Credenti // RmdirAt removes the directory at the given path. func (vfs *VirtualFilesystem) RmdirAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation) error { - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return err + if !pop.Path.Begin.Ok() { + if pop.Path.Absolute { + return syserror.EBUSY + } + return syserror.ENOENT } + if pop.FollowFinalSymlink { + ctx.Warningf("VirtualFilesystem.RmdirAt: file deletion paths can't follow final symlink") + return syserror.EINVAL + } + + rp := vfs.getResolvingPath(creds, pop) for { err := rp.mount.fs.impl.RmdirAt(ctx, rp) if err == nil { vfs.putResolvingPath(rp) return nil } + if checkInvariants { + if rp.canHandleError(err) && rp.Done() { + panic(fmt.Sprintf("%T.RmdirAt() consumed all path components and returned %T", rp.mount.fs.impl, err)) + } + } if !rp.handleError(err) { vfs.putResolvingPath(rp) return err @@ -346,10 +454,7 @@ func (vfs *VirtualFilesystem) RmdirAt(ctx context.Context, creds *auth.Credentia // SetStatAt changes metadata for the file at the given path. func (vfs *VirtualFilesystem) SetStatAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *SetStatOptions) error { - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return err - } + rp := vfs.getResolvingPath(creds, pop) for { err := rp.mount.fs.impl.SetStatAt(ctx, rp, *opts) if err == nil { @@ -365,10 +470,7 @@ func (vfs *VirtualFilesystem) SetStatAt(ctx context.Context, creds *auth.Credent // StatAt returns metadata for the file at the given path. func (vfs *VirtualFilesystem) StatAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *StatOptions) (linux.Statx, error) { - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return linux.Statx{}, err - } + rp := vfs.getResolvingPath(creds, pop) for { stat, err := rp.mount.fs.impl.StatAt(ctx, rp, *opts) if err == nil { @@ -385,10 +487,7 @@ func (vfs *VirtualFilesystem) StatAt(ctx context.Context, creds *auth.Credential // StatFSAt returns metadata for the filesystem containing the file at the // given path. func (vfs *VirtualFilesystem) StatFSAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation) (linux.Statfs, error) { - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return linux.Statfs{}, err - } + rp := vfs.getResolvingPath(creds, pop) for { statfs, err := rp.mount.fs.impl.StatFSAt(ctx, rp) if err == nil { @@ -404,16 +503,29 @@ func (vfs *VirtualFilesystem) StatFSAt(ctx context.Context, creds *auth.Credenti // SymlinkAt creates a symbolic link at the given path with the given target. func (vfs *VirtualFilesystem) SymlinkAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, target string) error { - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return err + if !pop.Path.Begin.Ok() { + if pop.Path.Absolute { + return syserror.EEXIST + } + return syserror.ENOENT + } + if pop.FollowFinalSymlink { + ctx.Warningf("VirtualFilesystem.SymlinkAt: file creation paths can't follow final symlink") + return syserror.EINVAL } + + rp := vfs.getResolvingPath(creds, pop) for { err := rp.mount.fs.impl.SymlinkAt(ctx, rp, target) if err == nil { vfs.putResolvingPath(rp) return nil } + if checkInvariants { + if rp.canHandleError(err) && rp.Done() { + panic(fmt.Sprintf("%T.SymlinkAt() consumed all path components and returned %T", rp.mount.fs.impl, err)) + } + } if !rp.handleError(err) { vfs.putResolvingPath(rp) return err @@ -423,16 +535,29 @@ func (vfs *VirtualFilesystem) SymlinkAt(ctx context.Context, creds *auth.Credent // UnlinkAt deletes the non-directory file at the given path. func (vfs *VirtualFilesystem) UnlinkAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation) error { - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return err + if !pop.Path.Begin.Ok() { + if pop.Path.Absolute { + return syserror.EBUSY + } + return syserror.ENOENT + } + if pop.FollowFinalSymlink { + ctx.Warningf("VirtualFilesystem.UnlinkAt: file deletion paths can't follow final symlink") + return syserror.EINVAL } + + rp := vfs.getResolvingPath(creds, pop) for { err := rp.mount.fs.impl.UnlinkAt(ctx, rp) if err == nil { vfs.putResolvingPath(rp) return nil } + if checkInvariants { + if rp.canHandleError(err) && rp.Done() { + panic(fmt.Sprintf("%T.UnlinkAt() consumed all path components and returned %T", rp.mount.fs.impl, err)) + } + } if !rp.handleError(err) { vfs.putResolvingPath(rp) return err @@ -443,10 +568,7 @@ func (vfs *VirtualFilesystem) UnlinkAt(ctx context.Context, creds *auth.Credenti // ListxattrAt returns all extended attribute names for the file at the given // path. func (vfs *VirtualFilesystem) ListxattrAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation) ([]string, error) { - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return nil, err - } + rp := vfs.getResolvingPath(creds, pop) for { names, err := rp.mount.fs.impl.ListxattrAt(ctx, rp) if err == nil { @@ -471,10 +593,7 @@ func (vfs *VirtualFilesystem) ListxattrAt(ctx context.Context, creds *auth.Crede // GetxattrAt returns the value associated with the given extended attribute // for the file at the given path. func (vfs *VirtualFilesystem) GetxattrAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, name string) (string, error) { - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return "", err - } + rp := vfs.getResolvingPath(creds, pop) for { val, err := rp.mount.fs.impl.GetxattrAt(ctx, rp, name) if err == nil { @@ -491,10 +610,7 @@ func (vfs *VirtualFilesystem) GetxattrAt(ctx context.Context, creds *auth.Creden // SetxattrAt changes the value associated with the given extended attribute // for the file at the given path. func (vfs *VirtualFilesystem) SetxattrAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, opts *SetxattrOptions) error { - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return err - } + rp := vfs.getResolvingPath(creds, pop) for { err := rp.mount.fs.impl.SetxattrAt(ctx, rp, *opts) if err == nil { @@ -510,10 +626,7 @@ func (vfs *VirtualFilesystem) SetxattrAt(ctx context.Context, creds *auth.Creden // RemovexattrAt removes the given extended attribute from the file at rp. func (vfs *VirtualFilesystem) RemovexattrAt(ctx context.Context, creds *auth.Credentials, pop *PathOperation, name string) error { - rp, err := vfs.getResolvingPath(creds, pop) - if err != nil { - return err - } + rp := vfs.getResolvingPath(creds, pop) for { err := rp.mount.fs.impl.RemovexattrAt(ctx, rp, name) if err == nil { diff --git a/pkg/syserror/syserror.go b/pkg/syserror/syserror.go index 1987e89cc..2269f6237 100644 --- a/pkg/syserror/syserror.go +++ b/pkg/syserror/syserror.go @@ -45,6 +45,7 @@ var ( ELIBBAD = error(syscall.ELIBBAD) ELOOP = error(syscall.ELOOP) EMFILE = error(syscall.EMFILE) + EMLINK = error(syscall.EMLINK) EMSGSIZE = error(syscall.EMSGSIZE) ENAMETOOLONG = error(syscall.ENAMETOOLONG) ENOATTR = ENODATA |