diff options
Diffstat (limited to 'pkg/sentry/vfs/file_description.go')
| -rw-r--r-- | pkg/sentry/vfs/file_description.go | 129 |
1 files changed, 122 insertions, 7 deletions
diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go index 6afe280bc..5bac660c7 100644 --- a/pkg/sentry/vfs/file_description.go +++ b/pkg/sentry/vfs/file_description.go @@ -18,12 +18,14 @@ import ( "sync/atomic" "gvisor.dev/gvisor/pkg/abi/linux" + "gvisor.dev/gvisor/pkg/context" "gvisor.dev/gvisor/pkg/sentry/arch" - "gvisor.dev/gvisor/pkg/sentry/context" + "gvisor.dev/gvisor/pkg/sentry/fs/lock" "gvisor.dev/gvisor/pkg/sentry/kernel/auth" "gvisor.dev/gvisor/pkg/sentry/memmap" - "gvisor.dev/gvisor/pkg/sentry/usermem" + "gvisor.dev/gvisor/pkg/sync" "gvisor.dev/gvisor/pkg/syserror" + "gvisor.dev/gvisor/pkg/usermem" "gvisor.dev/gvisor/pkg/waiter" ) @@ -45,12 +47,32 @@ type FileDescription struct { // memory operations. statusFlags uint32 + // epolls is the set of epollInterests registered for this FileDescription. + // epolls is protected by epollMu. + epollMu sync.Mutex + epolls map[*epollInterest]struct{} + // vd is the filesystem location at which this FileDescription was opened. // A reference is held on vd. vd is immutable. vd VirtualDentry + // opts contains options passed to FileDescription.Init(). opts is + // immutable. opts FileDescriptionOptions + // readable is MayReadFileWithOpenFlags(statusFlags). readable is + // immutable. + // + // readable is analogous to Linux's FMODE_READ. + readable bool + + // writable is MayWriteFileWithOpenFlags(statusFlags). If writable is true, + // the FileDescription holds a write count on vd.mount. writable is + // immutable. + // + // writable is analogous to Linux's FMODE_WRITE. + writable bool + // impl is the FileDescriptionImpl associated with this Filesystem. impl is // immutable. This should be the last field in FileDescription. impl FileDescriptionImpl @@ -77,10 +99,17 @@ type FileDescriptionOptions struct { UseDentryMetadata bool } -// Init must be called before first use of fd. It takes references on mnt and -// d. statusFlags is the initial file description status flags, which is -// usually the full set of flags passed to open(2). -func (fd *FileDescription) Init(impl FileDescriptionImpl, statusFlags uint32, mnt *Mount, d *Dentry, opts *FileDescriptionOptions) { +// Init must be called before first use of fd. If it succeeds, it takes +// references on mnt and d. statusFlags is the initial file description status +// flags, which is usually the full set of flags passed to open(2). +func (fd *FileDescription) Init(impl FileDescriptionImpl, statusFlags uint32, mnt *Mount, d *Dentry, opts *FileDescriptionOptions) error { + writable := MayWriteFileWithOpenFlags(statusFlags) + if writable { + if err := mnt.CheckBeginWrite(); err != nil { + return err + } + } + fd.refs = 1 fd.statusFlags = statusFlags | linux.O_LARGEFILE fd.vd = VirtualDentry{ @@ -89,7 +118,10 @@ func (fd *FileDescription) Init(impl FileDescriptionImpl, statusFlags uint32, mn } fd.vd.IncRef() fd.opts = *opts + fd.readable = MayReadFileWithOpenFlags(statusFlags) + fd.writable = writable fd.impl = impl + return nil } // IncRef increments fd's reference count. @@ -116,7 +148,27 @@ func (fd *FileDescription) TryIncRef() bool { // DecRef decrements fd's reference count. func (fd *FileDescription) DecRef() { if refs := atomic.AddInt64(&fd.refs, -1); refs == 0 { + // Unregister fd from all epoll instances. + fd.epollMu.Lock() + epolls := fd.epolls + fd.epolls = nil + fd.epollMu.Unlock() + for epi := range epolls { + ep := epi.epoll + ep.interestMu.Lock() + // Check that epi has not been concurrently unregistered by + // EpollInstance.DeleteInterest() or EpollInstance.Release(). + if _, ok := ep.interest[epi.key]; ok { + fd.EventUnregister(&epi.waiter) + ep.removeLocked(epi) + } + ep.interestMu.Unlock() + } + // Release implementation resources. fd.impl.Release() + if fd.writable { + fd.vd.mount.EndWrite() + } fd.vd.DecRef() } else if refs < 0 { panic("FileDescription.DecRef() called without holding a reference") @@ -194,6 +246,16 @@ func (fd *FileDescription) SetStatusFlags(ctx context.Context, creds *auth.Crede return nil } +// IsReadable returns true if fd was opened for reading. +func (fd *FileDescription) IsReadable() bool { + return fd.readable +} + +// IsWritable returns true if fd was opened for writing. +func (fd *FileDescription) IsWritable() bool { + return fd.writable +} + // Impl returns the FileDescriptionImpl associated with fd. func (fd *FileDescription) Impl() FileDescriptionImpl { return fd.impl @@ -241,6 +303,8 @@ type FileDescriptionImpl interface { // Errors: // // - If opts.Flags specifies unsupported options, PRead returns EOPNOTSUPP. + // + // Preconditions: The FileDescription was opened for reading. PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts ReadOptions) (int64, error) // Read is similar to PRead, but does not specify an offset. @@ -254,6 +318,8 @@ type FileDescriptionImpl interface { // Errors: // // - If opts.Flags specifies unsupported options, Read returns EOPNOTSUPP. + // + // Preconditions: The FileDescription was opened for reading. Read(ctx context.Context, dst usermem.IOSequence, opts ReadOptions) (int64, error) // PWrite writes src to the file, starting at the given offset, and returns @@ -268,6 +334,8 @@ type FileDescriptionImpl interface { // // - If opts.Flags specifies unsupported options, PWrite returns // EOPNOTSUPP. + // + // Preconditions: The FileDescription was opened for writing. 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 @@ -281,6 +349,8 @@ type FileDescriptionImpl interface { // Errors: // // - If opts.Flags specifies unsupported options, Write returns EOPNOTSUPP. + // + // Preconditions: The FileDescription was opened for writing. Write(ctx context.Context, src usermem.IOSequence, opts WriteOptions) (int64, error) // IterDirents invokes cb on each entry in the directory represented by the @@ -324,7 +394,25 @@ type FileDescriptionImpl interface { // Removexattr removes the given extended attribute from the file. Removexattr(ctx context.Context, name string) error - // TODO: file locking + // LockBSD tries to acquire a BSD-style advisory file lock. + // + // TODO(gvisor.dev/issue/1480): BSD-style file locking + LockBSD(ctx context.Context, uid lock.UniqueID, t lock.LockType, block lock.Blocker) error + + // LockBSD releases a BSD-style advisory file lock. + // + // TODO(gvisor.dev/issue/1480): BSD-style file locking + UnlockBSD(ctx context.Context, uid lock.UniqueID) error + + // LockPOSIX tries to acquire a POSIX-style advisory file lock. + // + // TODO(gvisor.dev/issue/1480): POSIX-style file locking + LockPOSIX(ctx context.Context, uid lock.UniqueID, t lock.LockType, rng lock.LockRange, block lock.Blocker) error + + // UnlockPOSIX releases a POSIX-style advisory file lock. + // + // TODO(gvisor.dev/issue/1480): POSIX-style file locking + UnlockPOSIX(ctx context.Context, uid lock.UniqueID, rng lock.LockRange) error } // Dirent holds the information contained in struct linux_dirent64. @@ -407,15 +495,36 @@ func (fd *FileDescription) StatFS(ctx context.Context) (linux.Statfs, error) { return fd.impl.StatFS(ctx) } +// Readiness returns fd's I/O readiness. +func (fd *FileDescription) Readiness(mask waiter.EventMask) waiter.EventMask { + return fd.impl.Readiness(mask) +} + +// EventRegister registers e for I/O readiness events in mask. +func (fd *FileDescription) EventRegister(e *waiter.Entry, mask waiter.EventMask) { + fd.impl.EventRegister(e, mask) +} + +// EventUnregister unregisters e for I/O readiness events. +func (fd *FileDescription) EventUnregister(e *waiter.Entry) { + fd.impl.EventUnregister(e) +} + // PRead reads from the file represented by fd 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. func (fd *FileDescription) PRead(ctx context.Context, dst usermem.IOSequence, offset int64, opts ReadOptions) (int64, error) { + if !fd.readable { + return 0, syserror.EBADF + } return fd.impl.PRead(ctx, dst, offset, opts) } // Read is similar to PRead, but does not specify an offset. func (fd *FileDescription) Read(ctx context.Context, dst usermem.IOSequence, opts ReadOptions) (int64, error) { + if !fd.readable { + return 0, syserror.EBADF + } return fd.impl.Read(ctx, dst, opts) } @@ -423,11 +532,17 @@ func (fd *FileDescription) Read(ctx context.Context, dst usermem.IOSequence, opt // offset, and returns the number of bytes written. PWrite is permitted to // return partial writes with a nil error. func (fd *FileDescription) PWrite(ctx context.Context, src usermem.IOSequence, offset int64, opts WriteOptions) (int64, error) { + if !fd.writable { + return 0, syserror.EBADF + } return fd.impl.PWrite(ctx, src, offset, opts) } // Write is similar to PWrite, but does not specify an offset. func (fd *FileDescription) Write(ctx context.Context, src usermem.IOSequence, opts WriteOptions) (int64, error) { + if !fd.writable { + return 0, syserror.EBADF + } return fd.impl.Write(ctx, src, opts) } |