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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
2020-06-22Only allow regular files, sockets, pipes, and char devices to be imported.Dean Deng
PiperOrigin-RevId: 317796028
2020-06-22Check for invalid trailing / when traversing path in gofer OpenAt.Dean Deng
Updates #2923. PiperOrigin-RevId: 317700049
2020-06-21Fix vfs2 extended attributes.Dean Deng
Correct behavior when given zero size arguments and trying to set user.* xattrs on files other than regular files or directories. Updates #2923. PiperOrigin-RevId: 317590409
2020-06-19Fix bugs in vfs2 to make symlink tests pass.Dean Deng
- Return ENOENT if target path is empty. - Make sure open(2) with O_CREAT|O_EXCL returns EEXIST when necessary. - Correctly update atime in tmpfs using touchATime(). Updates #2923. PiperOrigin-RevId: 317382655
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
2020-06-19Fix vfs2 handling of preadv2/pwritev2 flags.Dean Deng
Check for unsupported flags, and silently support RWF_HIPRI by doing nothing. From pkg/abi/linux/file.go: "gVisor does not implement the RWF_HIPRI feature, but the flag is accepted as a valid flag argument for preadv2/pwritev2." Updates #2923. PiperOrigin-RevId: 317330631
2020-06-19Don't adjust parent link count if we replace a child dir with another.Dean Deng
Updates #2923. PiperOrigin-RevId: 317314460
2020-06-19Support all seek options in gofer specialFileFD.Seek.Dean Deng
Updates #2923. PiperOrigin-RevId: 317298186
2020-06-19Fix synthetic file bugs in gofer fs.Dean Deng
Always check if a synthetic file already exists at a location before creating a file there, and do not try to delete synthetic gofer files from the remote fs. This fixes runsc_ptrace socket tests that create/unlink synthetic, named socket files. Updates #2923. PiperOrigin-RevId: 317293648
2020-06-18Fix vfs2 tmpfs link permission checks.Dean Deng
Updates #2923. PiperOrigin-RevId: 317246916
2020-06-18Remove various uses of 'whitelist'Michael Pratt
Updates #2972 PiperOrigin-RevId: 317113059
2020-06-17Implement Sync() to directoriesFabricio Voznika
Updates #1035, #1199 PiperOrigin-RevId: 317028108
2020-06-17Remove various uses of 'blacklist'Michael Pratt
Updates #2972 PiperOrigin-RevId: 316942245
2020-06-17Refactor host.canMap.Dean Deng
Simplify the canMap check. We do not have plans to allow mmap for anything beyond regular files, so we can just inline canMap() as a simple file mode check. Updates #1672. PiperOrigin-RevId: 316929654
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
2020-06-16Miscellaneous VFS2 fixes.Jamie Liu
PiperOrigin-RevId: 316627764
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
2020-06-11Don't copy structs with sync.Mutex during initializationFabricio Voznika
During inititalization inode struct was copied around, but it isn't great pratice to copy it around since it contains ref count and sync.Mutex. Updates #1480 PiperOrigin-RevId: 315983788
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
2020-06-08Implement VFS2 tmpfs mount options.Jamie Liu
As in VFS1, the mode, uid, and gid options are supported. Updates #1197 PiperOrigin-RevId: 315340510
2020-06-05Implement mount(2) and umount2(2) for VFS2.Rahat Mahmood
This is mostly syscall plumbing, VFS2 already implements the internals of mounts. In addition to the syscall defintions, the following mount-related mechanisms are updated: - Implement MS_NOATIME for VFS2, but only for tmpfs and goferfs. The other VFS2 filesystems don't implement node-level timestamps yet. - Implement the 'mode', 'uid' and 'gid' mount options for VFS2's tmpfs. - Plumb mount namespace ownership, which is necessary for checking appropriate capabilities during mount(2). Updates #1035 PiperOrigin-RevId: 315035352
2020-06-01Fix VFS2 gofer open(O_CREAT) reference leak.Jamie Liu
gofer.filesystem.createAndOpenChildLocked() doesn't need to take a reference on the new dentry since vfs.FileDescription.Init() will do so. PiperOrigin-RevId: 314242127
2020-06-01Handle gofer blocking opens of host named pipes in VFS2.Jamie Liu
Using tee instead of read to detect when a O_RDONLY|O_NONBLOCK pipe FD has a writer circumvents the problem of what to do with the byte read from the pipe, avoiding much of the complexity of the fdpipe package. PiperOrigin-RevId: 314216146
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
2020-05-27Correctly update link and ref counts in rmdir.Dean Deng
Inotify sends events when a watch target is reaches a link count of 0 (see include/linux/fsnotify.h:fsnotify_inoderemove). Currently, we do not account for both dir/ and dir/.. in unlink, causing syscalls/linux/inotify.cc:WatchTargetDeletionGeneratesEvent to fail because the expected inotify events are not generated. Furthermore, we should DecRef() once the inode reaches zero links; otherwise, we will leak a reference. PiperOrigin-RevId: 313502091
2020-05-26Support dfltuid and dfltgid mount options in the VFS2 gofer client.Jamie Liu
PiperOrigin-RevId: 313332542
2020-05-26Implement splice(2) and tee(2) for VFS2.Jamie Liu
Updates #138 PiperOrigin-RevId: 313326354
2020-05-20Move fsimpl/host file offset from inode to fileDescription.Dean Deng
PiperOrigin-RevId: 312559861
2020-05-19Implement mmap for host fs in vfs2.Dean Deng
In VFS1, both fs/host and fs/gofer used the same utils for host file mappings. Refactor parts of fsimpl/gofer to create similar utils to share with fsimpl/host (memory accounting code moved to fsutil, page rounding arithmetic moved to usermem). Updates #1476. PiperOrigin-RevId: 312345090
2020-05-18Remove IfChange/ThenChange lint from VFS2Fabricio Voznika
As new functionality is added to VFS2, corresponding files in VFS1 don't need to be changed. PiperOrigin-RevId: 312153799
2020-05-14Make utimes_test pass on VFS2.Jamie Liu
PiperOrigin-RevId: 311657502
2020-05-14Port memfd_create to vfs2 and finish implementation of file seals.Nicolas Lacasse
Closes #2612. PiperOrigin-RevId: 311548074
2020-05-13Resolve remaining TODOs for tmpfs.Nicolas Lacasse
Closes #1197 PiperOrigin-RevId: 311438223
2020-05-13Enable overlayfs_stale_read by default for runsc.Jamie Liu
Linux 4.18 and later make reads and writes coherent between pre-copy-up and post-copy-up FDs representing the same file on an overlay filesystem. However, memory mappings remain incoherent: - Documentation/filesystems/overlayfs.rst, "Non-standard behavior": "If a file residing on a lower layer is opened for read-only and then memory mapped with MAP_SHARED, then subsequent changes to the file are not reflected in the memory mapping." - fs/overlay/file.c:ovl_mmap() passes through to the underlying FD without any management of coherence in the overlay. - Experimentally on Linux 5.2: ``` $ cat mmap_cat_page.c #include <err.h> #include <fcntl.h> #include <stdio.h> #include <string.h> #include <sys/mman.h> #include <unistd.h> int main(int argc, char **argv) { if (argc < 2) { errx(1, "syntax: %s [FILE]", argv[0]); } const int fd = open(argv[1], O_RDONLY); if (fd < 0) { err(1, "open(%s)", argv[1]); } const size_t page_size = sysconf(_SC_PAGE_SIZE); void* page = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0); if (page == MAP_FAILED) { err(1, "mmap"); } for (;;) { write(1, page, strnlen(page, page_size)); if (getc(stdin) == EOF) { break; } } return 0; } $ gcc -O2 -o mmap_cat_page mmap_cat_page.c $ mkdir lowerdir upperdir workdir overlaydir $ echo old > lowerdir/file $ sudo mount -t overlay -o "lowerdir=lowerdir,upperdir=upperdir,workdir=workdir" none overlaydir $ ./mmap_cat_page overlaydir/file old ^Z [1]+ Stopped ./mmap_cat_page overlaydir/file $ echo new > overlaydir/file $ cat overlaydir/file new $ fg ./mmap_cat_page overlaydir/file old ``` Therefore, while the VFS1 gofer client's behavior of reopening read FDs is only necessary pre-4.18, replacing existing memory mappings (in both sentry and application address spaces) with mappings of the new FD is required regardless of kernel version, and this latter behavior is common to both VFS1 and VFS2. Re-document accordingly, and change the runsc flag to enabled by default. New test: - Before this CL: https://source.cloud.google.com/results/invocations/5b222d2c-e918-4bae-afc4-407f5bac509b - After this CL: https://source.cloud.google.com/results/invocations/f28c747e-d89c-4d8c-a461-602b33e71aab PiperOrigin-RevId: 311361267
2020-05-11Internal change.Jamie Liu
PiperOrigin-RevId: 311046755
2020-05-11Add fsimpl/gofer.InternalFilesystemOptions.OpenSocketsByConnecting.Jamie Liu
PiperOrigin-RevId: 311014995
2020-05-08Pass flags to fsimpl/host.inode.open().Jamie Liu
This has two effects: It makes flags passed to open("/proc/[pid]/fd/[hostfd]") effective, and it prevents imported pipes/sockets/character devices from being opened with O_NONBLOCK unconditionally (because the underlying host FD was set to non-blocking in ImportFD()). PiperOrigin-RevId: 310596062
2020-05-07Allocate device numbers for VFS2 filesystems.Jamie Liu
Updates #1197, #1198, #1672 PiperOrigin-RevId: 310432006
2020-05-07Move pkg/sentry/vfs/{eventfd,timerfd} to new packages in pkg/sentry/fsimpl.Nicolas Lacasse
They don't depend on anything in VFS2, so they should be their own packages. PiperOrigin-RevId: 310416807
2020-05-07Port signalfd to vfs2.Nicolas Lacasse
PiperOrigin-RevId: 310404113
2020-05-06Add maximum memory limit.Nicolas Lacasse
PiperOrigin-RevId: 310179277
2020-05-05Update vfs2 socket TODOs.Dean Deng
Three updates: - Mark all vfs2 socket syscalls as supported. - Use the same dev number and ino number generator for all types of sockets, unlike in VFS1. - Do not use host fd for hostinet metadata. Fixes #1476, #1478, #1484, 1485, #2017. PiperOrigin-RevId: 309994579
2020-05-05Update comments for synthetic gofer files in vfs2.Dean Deng
PiperOrigin-RevId: 309966538
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
2020-05-05Translate p9.NoUID/GID to OverflowUID/GID.Jamie Liu
p9.NoUID/GID (== uint32(-1) == auth.NoID) is not a valid auth.KUID/KGID; in particular, using it for file ownership causes capabilities to be ineffective since file capabilities require that the file's KUID and KGID are mapped into the capability holder's user namespace [1], and auth.NoID is not mapped into any user namespace. Map p9.NoUID/GID to a different, valid KUID/KGID; in the unlikely case that an application actually using the overflow KUID/KGID attempts an operation that is consequently permitted by client permission checks, the remote operation will still fail with EPERM. Since this changes the VFS2 gofer client to no longer ignore the invalid IDs entirely, this CL both permits and requires that we change synthetic mount point creation to use root credentials. [1] See fs.Inode.CheckCapability or vfs.GenericCheckPermissions. PiperOrigin-RevId: 309856455
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
2020-05-04Add TTY support on VFS2 to runscFabricio Voznika
Updates #1623, #1487 PiperOrigin-RevId: 309777922
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