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2020-06-24Fix procfs bugs in vfs2.Dean Deng
- Support writing on proc/[pid]/{uid,gid}map - Return EIO for writing to static files. Updates #2923. PiperOrigin-RevId: 318188503
2020-06-23Resolve remaining inotify TODOs.Dean Deng
Also refactor HandleDeletion(). Updates #1479. PiperOrigin-RevId: 317989000
2020-06-23Support inotify in vfs2 gofer fs.Dean Deng
Because there is no inode structure stored in the sandbox, inotify watches must be held on the dentry. This would be an issue in the presence of hard links, where multiple dentries would need to share the same set of watches, but in VFS2, we do not support the internal creation of hard links on gofer fs. As a result, we make the assumption that every dentry corresponds to a unique inode. Furthermore, dentries can be cached and then evicted, even if the underlying file has not be deleted. We must prevent this from occurring if there are any watches that would be lost. Note that if the dentry was deleted or invalidated (d.vfsd.IsDead()), we should still destroy it along with its watches. Additionally, when a dentry’s last watch is removed, we cache it if it also has zero references. This way, the dentry can eventually be evicted from memory if it is no longer needed. This is accomplished with a new dentry method, OnZeroWatches(), which is called by Inotify.RmWatch and Inotify.Release. Note that it must be called after all inotify locks are released to avoid violating lock order. Stress tests are added to make sure that inotify operations don't deadlock with gofer.OnZeroWatches. Updates #1479. PiperOrigin-RevId: 317958034
2020-06-19Fix vfs2 proc/self/fd dirent iteration.Dean Deng
Make proc/self/fd iteration work properly. Also, the comment on kernfs.Inode.IterDirents did not accurately reflect how parameters should be used/were used in kernfs.Inode impls other than fdDir. Updates #2923. PiperOrigin-RevId: 317370325
2020-06-17Implement POSIX locksFabricio Voznika
- Change FileDescriptionImpl Lock/UnlockPOSIX signature to take {start,length,whence}, so the correct offset can be calculated in the implementations. - Create PosixLocker interface to make it possible to share the same locking code from different implementations. Closes #1480 PiperOrigin-RevId: 316910286
2020-06-11Add //pkg/sentry/fsimpl/overlay.Jamie Liu
Major differences from existing overlay filesystems: - Linux allows lower layers in an overlay to require revalidation, but not the upper layer. VFS1 allows the upper layer in an overlay to require revalidation, but not the lower layer. VFS2 does not allow any layers to require revalidation. (Now that vfs.MkdirOptions.ForSyntheticMountpoint exists, no uses of overlay in VFS1 are believed to require upper layer revalidation; in particular, the requirement that the upper layer support the creation of "trusted." extended attributes for whiteouts effectively required the upper filesystem to be tmpfs in most cases.) - Like VFS1, but unlike Linux, VFS2 overlay does not attempt to make mutations of the upper layer atomic using a working directory and features like RENAME_WHITEOUT. (This may change in the future, since not having a working directory makes error recovery for some operations, e.g. rmdir, particularly painful.) - Like Linux, but unlike VFS1, VFS2 represents whiteouts using character devices with rdev == 0; the equivalent of the whiteout attribute on directories is xattr trusted.overlay.opaque = "y"; and there is no equivalent to the whiteout attribute on non-directories since non-directories are never merged with lower layers. - Device and inode numbers work as follows: - In Linux, modulo the xino feature and a special case for when all layers are the same filesystem: - Directories use the overlay filesystem's device number and an ephemeral inode number assigned by the overlay. - Non-directories that have been copied up use the device and inode number assigned by the upper filesystem. - Non-directories that have not been copied up use a per-(overlay, layer)-pair device number and the inode number assigned by the lower filesystem. - In VFS1, device and inode numbers always come from the lower layer unless "whited out"; this has the adverse effect of requiring interaction with the lower filesystem even for non-directory files that exist on the upper layer. - In VFS2, device and inode numbers are assigned as in Linux, except that xino and the samefs special case are not supported. - Like Linux, but unlike VFS1, VFS2 does not attempt to maintain memory mapping coherence across copy-up. (This may have to change in the future, as users may be dependent on this property.) - Like Linux, but unlike VFS1, VFS2 uses the overlayfs mounter's credentials when interacting with the overlay's layers, rather than the caller's. - Like Linux, but unlike VFS1, VFS2 permits multiple lower layers in an overlay. - Like Linux, but unlike VFS1, VFS2's overlay filesystem is application-mountable. Updates #1199 PiperOrigin-RevId: 316019067
2020-06-09Implement flock(2) in VFS2Fabricio Voznika
LockFD is the generic implementation that can be embedded in FileDescriptionImpl implementations. Unique lock ID is maintained in vfs.FileDescription and is created on demand. Updates #1480 PiperOrigin-RevId: 315604825
2020-05-29Implement IN_EXCL_UNLINK inotify option in vfs2.Dean Deng
Limited to tmpfs. Inotify support in other filesystem implementations to follow. Updates #1479 PiperOrigin-RevId: 313828648
2020-05-29Fix the smallest of typos.Dean Deng
PiperOrigin-RevId: 313817646
2020-05-29Port inotify to vfs2, with support in tmpfs.Dean Deng
Support in other filesystem impls is still needed. Unlike in Linux and vfs1, we need to plumb inotify down to each filesystem implementation in order to keep track of links/inode structures properly. IN_EXCL_UNLINK still needs to be implemented, as well as a few inotify hooks that are not present in either vfs1 or vfs2. Those will be addressed in subsequent changes. Updates #1479. PiperOrigin-RevId: 313781995
2020-05-07Allocate device numbers for VFS2 filesystems.Jamie Liu
Updates #1197, #1198, #1672 PiperOrigin-RevId: 310432006
2020-05-05Return correct name for imported host filesFabricio Voznika
Implement PrependPath() in host.filesystem to correctly format name for host files. Updates #1672 PiperOrigin-RevId: 309959135
2020-05-04Remove kernfs.Filesystem cast from GenericDirectoryFDFabricio Voznika
This allows for kerfs.Filesystem to be overridden by different implementations. Updates #1672 PiperOrigin-RevId: 309809321
2020-04-28Fix Unix socket permissions.Dean Deng
Enforce write permission checks in BoundEndpointAt, which corresponds to the permission checks in Linux (net/unix/af_unix.c:unix_find_other). Also, create bound socket files with the correct permissions in VFS2. Fixes #2324. PiperOrigin-RevId: 308949084
2020-04-28Support pipes and sockets in VFS2 gofer fs.Dean Deng
Named pipes and sockets can be represented in two ways in gofer fs: 1. As a file on the remote filesystem. In this case, all file operations are passed through 9p. 2. As a synthetic file that is internal to the sandbox. In this case, the dentry stores an endpoint or VFSPipe for sockets and pipes respectively, which replaces interactions with the remote fs through the gofer. In gofer.filesystem.MknodAt, we attempt to call mknod(2) through 9p, and if it fails, fall back to the synthetic version. Updates #1200. PiperOrigin-RevId: 308828161
2020-04-24Plumb context.Context into kernfs.Inode.Open().Dean Deng
PiperOrigin-RevId: 308304793
2020-04-24Fixes for procfsFabricio Voznika
- Return ENOENT for /proc/[pid]/task if task is zoombied or terminated - Allow directory to be Seek() to the end - Construct synthetic files for /proc/[pid]/ns/* - Changed GenericDirectoryFD.Init to not register with FileDescription, otherwise other implementation cannot change behavior. Updates #1195,1193 PiperOrigin-RevId: 308294649
2020-04-23Port devpts to VFS2.Nicolas Lacasse
PiperOrigin-RevId: 308164359
2020-04-21Misc VFS2 fixesFabricio Voznika
- Fix defer operation ordering in kernfs.Filesystem.AccessAt() - Add AT_NULL entry in proc/pid/auvx - Fix line padding in /proc/pid/maps - Fix linux_dirent serialization for getdents(2) - Remove file creation flags from vfs.FileDescription.statusFlags() Updates #1193, #1035 PiperOrigin-RevId: 307704159
2020-04-21Remove filesystem structure from vfs.Dentry.Jamie Liu
This change: - Drastically simplifies the synchronization model: filesystem structure is both implementation-defined and implementation-synchronized. - Allows implementations of vfs.DentryImpl to use implementation-specific dentry types, reducing casts during path traversal. - Doesn't require dentries representing non-directory files to waste space on a map of children. - Allows dentry revalidation and mount lookup to be correctly ordered (fixed FIXME in fsimpl/gofer/filesystem.go). - Removes the need to have two separate maps in gofer.dentry (dentry.vfsd.children and dentry.negativeChildren) for positive and negative lookups respectively. //pkg/sentry/fsimpl/tmpfs/benchmark_test.go: name old time/op new time/op delta VFS2TmpfsStat/1-112 172ns ± 4% 165ns ± 3% -4.08% (p=0.002 n=9+9) VFS2TmpfsStat/2-112 199ns ± 3% 195ns ±10% ~ (p=0.132 n=8+9) VFS2TmpfsStat/3-112 230ns ± 2% 216ns ± 2% -6.15% (p=0.000 n=8+8) VFS2TmpfsStat/8-112 390ns ± 2% 358ns ± 4% -8.33% (p=0.000 n=9+8) VFS2TmpfsStat/64-112 2.20µs ± 3% 2.01µs ± 3% -8.48% (p=0.000 n=10+8) VFS2TmpfsStat/100-112 3.42µs ± 9% 3.08µs ± 2% -9.82% (p=0.000 n=9+8) VFS2TmpfsMountStat/1-112 278ns ± 1% 286ns ±15% ~ (p=0.712 n=8+10) VFS2TmpfsMountStat/2-112 311ns ± 4% 298ns ± 2% -4.27% (p=0.000 n=9+8) VFS2TmpfsMountStat/3-112 339ns ± 3% 330ns ± 9% ~ (p=0.070 n=8+9) VFS2TmpfsMountStat/8-112 503ns ± 3% 466ns ± 3% -7.38% (p=0.000 n=8+8) VFS2TmpfsMountStat/64-112 2.53µs ±16% 2.17µs ± 7% -14.19% (p=0.000 n=10+9) VFS2TmpfsMountStat/100-112 3.60µs ± 4% 3.30µs ± 8% -8.33% (p=0.001 n=8+9) Updates #1035 PiperOrigin-RevId: 307655892
2020-04-10Port extended attributes to VFS2.Dean Deng
As in VFS1, we only support the user.* namespace. Plumbing is added to tmpfs and goferfs. Note that because of the slightly different order of checks between VFS2 and Linux, one of the xattr tests needs to be relaxed slightly. Fixes #2363. PiperOrigin-RevId: 305985121
2020-04-08Clean up TODOsFabricio Voznika
PiperOrigin-RevId: 305592245
2020-04-06Correctly implement magic symlinks in VFS2 procfs.Jamie Liu
Updates #1195 PiperOrigin-RevId: 305143567
2020-04-02Add NAME_MAX checks and update file timesFabricio Voznika
NAME_MAX should be enforced per filesystem implementation because other file systems may not have the same restriction. Gofer filesystem now keeps a reference to the kernel clock to avoid lookup in the Context on file access to update atime. Update access, modification, and status change times in tmpfs. Updates #1197, #1198. PiperOrigin-RevId: 304527148
2020-03-27Add FilesystemType.Name method, and FilesystemType field to Filesystem struct.Nicolas Lacasse
Both have analogues in Linux: * struct file_system_type has a char *name field. * struct super_block keeps a pointer to the file_system_type. These fields are necessary to support the `filesystem type` field in /proc/[pid]/mountinfo. PiperOrigin-RevId: 303434063
2020-03-26Add BoundEndpointAt filesystem operation.Dean Deng
BoundEndpointAt() is needed to support Unix sockets bound at a file path, corresponding to BoundEndpoint() in VFS1. Updates #1476. PiperOrigin-RevId: 303258251
2020-03-26Combine file mode and isDir argumentsFabricio Voznika
Updates #1035 PiperOrigin-RevId: 303021328
2020-03-16Enforce file size rlimits in VFS2Fabricio Voznika
Updates #1035 PiperOrigin-RevId: 301255357
2020-03-16Add calls to vfs.CheckSetStat to fsimplsFabricio Voznika
Only gofer filesystem was calling vfs.CheckSetStat for vfs.FilesystemImpl.SetStatAt and vfs.FileDescriptionImpl.SetStat. Updates #1193, #1672, #1197 PiperOrigin-RevId: 301226522
2020-03-14Disallow kernfs.Inode.SetStat for readonly inodesFabricio Voznika
Updates #1195, #1193 PiperOrigin-RevId: 300950993
2020-03-13Add remaining procfs filesFabricio Voznika
Closes #1195 PiperOrigin-RevId: 300867055
2020-03-13Implement access/faccessat for VFS2.Dean Deng
Note that the raw faccessat system call does not actually take a flags argument; according to faccessat(2), the glibc wrapper implements the flags by using fstatat(2). Remove the flag argument that we try to extract from vfs1, which would just be a garbage value. Updates #1965 Fixes #2101 PiperOrigin-RevId: 300796067
2020-03-06Add plumbing for importing fds in VFS2, along with non-socket, non-TTY impl.Dean Deng
In VFS2, imported file descriptors are stored in a kernfs-based filesystem. Upon calling ImportFD, the host fd can be accessed in two ways: 1. a FileDescription that can be added to the FDTable, and 2. a Dentry in the host.filesystem mount, which we will want to access through magic symlinks in /proc/[pid]/fd/. An implementation of the kernfs.Inode interface stores a unique host fd. This inode can be inserted into file descriptions as well as dentries. This change also plumbs in three FileDescriptionImpls corresponding to fds for sockets, TTYs, and other files (only the latter is implemented here). These implementations will mostly make corresponding syscalls to the host. Where possible, the logic is ported over from pkg/sentry/fs/host. Updates #1672 PiperOrigin-RevId: 299417263
2020-02-14Allow vfs.IterDirentsCallback.Handle() to return an error.gVisor bot
This is easier than storing errors from e.g. CopyOut in the callback. PiperOrigin-RevId: 295230021
2020-02-14Inline vfs.VirtualFilesystem in Kernel structgVisor bot
This saves one pointer dereference per VFS access. Updates #1623 PiperOrigin-RevId: 295216176
2020-02-14Plumb VFS2 inside the SentrygVisor bot
- Added fsbridge package with interface that can be used to open and read from VFS1 and VFS2 files. - Converted ELF loader to use fsbridge - Added VFS2 types to FSContext - Added vfs.MountNamespace to ThreadGroup Updates #1623 PiperOrigin-RevId: 295183950
2020-02-13Add FileExec flag to OpenOptionsgVisor bot
This allow callers to say whether the file is being opened to be executed, so that the proper checks can be done from FilesystemImpl.OpenAt() Updates #1623 PiperOrigin-RevId: 295042595
2020-02-10Redirect FIXME to gvisor.devFabricio Voznika
PiperOrigin-RevId: 294272755
2020-01-28Add support for WritableSource in DynamicBytesFileDescriptionImplFabricio Voznika
WritableSource is a convenience interface used for files that can be written to, e.g. /proc/net/ipv4/tpc_sack. It reads max of 4KB and only from offset 0 which should cover most cases. It can be extended as neeed. Updates #1195 PiperOrigin-RevId: 292056924
2020-01-27Update package locations.Adin Scannell
Because the abi will depend on the core types for marshalling (usermem, context, safemem, safecopy), these need to be flattened from the sentry directory. These packages contain no sentry-specific details. PiperOrigin-RevId: 291811289
2020-01-27Standardize on tools directory.Adin Scannell
PiperOrigin-RevId: 291745021
2020-01-22De-duplicate common test functionality for VFS2 filesystems.Rahat Mahmood
PiperOrigin-RevId: 291041576
2020-01-22Move VFS2 handling of FD readability/writability to vfs.FileDescription.Jamie Liu
PiperOrigin-RevId: 291006713
2020-01-21Implement sysfs.Rahat Mahmood
PiperOrigin-RevId: 290822487
2020-01-16Add more files to /proc/[pid]/*Fabricio Voznika
Files not implemented require VFSv2 plumbing into the kernel. Also, cgroup is not implemented yet. Updates #1195 PiperOrigin-RevId: 290129176
2020-01-16Add remaining /proc/* and /proc/sys/* filesFabricio Voznika
Except for one under /proc/sys/net/ipv4/tcp_sack. /proc/pid/* is still incomplete. Updates #1195 PiperOrigin-RevId: 290120438
2020-01-09New sync package.Ian Gudger
* Rename syncutil to sync. * Add aliases to sync types. * Replace existing usage of standard library sync package. This will make it easier to swap out synchronization primitives. For example, this will allow us to use primitives from github.com/sasha-s/go-deadlock to check for lock ordering violations. Updates #1472 PiperOrigin-RevId: 289033387
2019-12-30Add VFS2 support for device special files.Jamie Liu
- Add FileDescriptionOptions.UseDentryMetadata, which reduces the amount of boilerplate needed for device FDs and the like between filesystems. - Switch back to having FileDescription.Init() take references on the Mount and Dentry; otherwise managing refcounts around failed calls to OpenDeviceSpecialFile() / Device.Open() is tricky. PiperOrigin-RevId: 287575574
2019-12-27Add VFS2 support for /proc/filesystems.Jamie Liu
Updates #1195 PiperOrigin-RevId: 287269106
2019-12-26Initial procfs implementation in VFSv2Fabricio Voznika
Updates #1195 PiperOrigin-RevId: 287227722