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2020-08-24Update inotify documentation for gofer filesystem.Dean Deng
We now allow hard links to be created within gofer fs (see github.com/google/gvisor/commit/f20e63e31b56784c596897e86f03441f9d05f567). Update the inotify documentation accordingly. PiperOrigin-RevId: 328177485
2020-08-20Consistent precondition formattingMichael Pratt
Our "Preconditions:" blocks are very useful to determine the input invariants, but they are bit inconsistent throughout the codebase, which makes them harder to read (particularly cases with 5+ conditions in a single paragraph). I've reformatted all of the cases to fit in simple rules: 1. Cases with a single condition are placed on a single line. 2. Cases with multiple conditions are placed in a bulleted list. This format has been added to the style guide. I've also mentioned "Postconditions:", though those are much less frequently used, and all uses already match this style. PiperOrigin-RevId: 327687465
2020-08-19Remove path walk from localFile.MknodFabricio Voznika
Replace mknod call with mknodat equivalent to protect against symlink attacks. Also added Mknod tests. Remove goferfs reliance on gofer to check for file existence before creating a synthetic entry. Updates #2923 PiperOrigin-RevId: 327544516
2020-08-18[vfs] Allow offsets for special files other than regular files.Ayush Ranjan
Some character and block devices can be seekable. So allow their FD to maintain file offset. PiperOrigin-RevId: 327370684
2020-08-18Don't set atime if mount is readonlyFabricio Voznika
Updates #1035 PiperOrigin-RevId: 327351475
2020-08-18Avoid holding locks when opening files in VFS2.Jamie Liu
Fixes #3243, #3521 PiperOrigin-RevId: 327308890
2020-08-17[vfs] Do O_DIRECTORY check after resolving symlinks.Ayush Ranjan
Fixes python runtime test test_glob. Updates #3515 We were checking is the to-be-opened dentry is a dir or not before resolving symlinks. We should check that after resolving symlinks. This was preventing us from opening a symlink which pointed to a directory with O_DIRECTORY. Also added this check in tmpfs and removed a duplicate check. PiperOrigin-RevId: 327085895
2020-08-13[vfs2][gofer] Fix file creation flags sent to gofer.Ayush Ranjan
Fixes php runtime test ext/standard/tests/file/readfile_basic.phpt Fixes #3516 fsgofers only want the access mode in the OpenFlags passed to Create(). If more flags are supplied (like O_APPEND in this case), read/write from that fd will fail with EBADF. See runsc/fsgofer/fsgofer.go:WriteAt() VFS2 was providing more than just access modes. So filtering the flags using p9.OpenFlagsModeMask == linux.O_ACCMODE fixes the issue. Gofer in VFS1 also only extracts the access mode flags while making the create RPC. See pkg/sentry/fs/gofer/path.go:Create() Even in VFS2, when we open a handle, we extract out only the access mode flags + O_TRUNC. See third_party/gvisor/pkg/sentry/fsimpl/gofer/handle.go:openHandle() Added a test for this. PiperOrigin-RevId: 326574829
2020-08-12[vfs2][gofer] Return appropriate errors when opening and creating files.Ayush Ranjan
Fixes php test ext/standard/tests/file/touch_variation5.phpt on vfs2. Updates #3516 Also spotted a bug with O_EXCL, where we did not return EEXIST when we tried to open the root of the filesystem with O_EXCL | O_CREAT. Added some more tests for open() corner cases. PiperOrigin-RevId: 326346863
2020-08-07Don't hold gofer.filesystem.renameMu during dentry destruction.Jamie Liu
PiperOrigin-RevId: 325546629
2020-08-07Mark dropped pages unevictable in fsimpl/gofer.dentry.destroyLocked.Jamie Liu
PiperOrigin-RevId: 325531657
2020-08-07Support separate read/write handles in fsimpl/gofer.dentry.Jamie Liu
PiperOrigin-RevId: 325490674
2020-08-07Try to update atime and mtime on VFS2 gofer files on dentry eviction.Jamie Liu
PiperOrigin-RevId: 325388385
2020-08-06Add LinkAt support to goferFabricio Voznika
Updates #1198 PiperOrigin-RevId: 325350818
2020-08-04Inline gofer.regularFileFD.pwriteLockedFabricio Voznika
Go compiler barely inlines anything, so inline by hand pwriteLocked since it's called from a single place. PiperOrigin-RevId: 324937734
2020-08-03Plumbing context.Context to DecRef() and Release().Nayana Bidari
context is passed to DecRef() and Release() which is needed for SO_LINGER implementation. PiperOrigin-RevId: 324672584
2020-07-27Move platform.File in memmapAndrei Vagin
The subsequent systrap changes will need to import memmap from the platform package. PiperOrigin-RevId: 323409486
2020-07-23Add permission checks to vfs2 truncate.Dean Deng
- Check write permission on truncate(2). Unlike ftruncate(2), truncate(2) fails if the user does not have write permissions on the file. - For gofers under InteropModeShared, check file type before making a truncate request. We should fail early and avoid making an rpc when possible. Furthermore, depending on the remote host's failure may give us unexpected behavior--if the host converts the truncate request to an ftruncate syscall on an open fd, we will get EINVAL instead of EISDIR. Updates #2923. PiperOrigin-RevId: 322913569
2020-07-23[vfs2][gofer] Fix update attributes race condition.Ayush Ranjan
We were getting the file attributes before locking the metadataMu which was causing stale updates to the file attributes. Fixes OpenTest_AppendConcurrentWrite. Updates #2923 PiperOrigin-RevId: 322804438
2020-07-22Add O_APPEND support in vfs2 gofer.Ayush Ranjan
Helps in fixing open syscall tests: AppendConcurrentWrite and AppendOnly. We also now update the file size for seekable special files (regular files) which we were not doing earlier. Updates #2923 PiperOrigin-RevId: 322670843
2020-07-14Update special file option name in comment.Dean Deng
PiperOrigin-RevId: 321269281
2020-07-13[vfs2] Make gofer metadata atomics consistentAyush Ranjan
For accessing metadata fields: - If metadataMu is locked, we can access without atomics - If metadataMu is unlocked, we should use atomics For mutating metadata fields: - Always lock metadataMu and use atomics. There were some instances of inconsistencies which have been fixed. PiperOrigin-RevId: 321022895
2020-07-06Call fdnotifier.UpdateFD() from fsimpl/gofer.specialFileFD.Jamie Liu
The fdnotifier package provides an API to a thread that continually epolls arbitrary host FDs. The set of events polled for each host FD is (intended to be) all events for which a waiter.Entry has expressed interest, as returned by waiter.Queue.Events() for the waiter.Queue registered to the given host FD. When the set of events changes (due to a change in the set of registered waiter.Entries), the mutator must call fdnotifier.UpdateFD() to recalculate the new event set and propagate it to the epoll FD. PiperOrigin-RevId: 319924719
2020-07-06Ensure sync is called for readonly fileFabricio Voznika
Calling sync on a readonly file flushes metadata that may have been modified, like last access time. Updates #1198 PiperOrigin-RevId: 319888290
2020-07-06Add inode number to synthetic dentriesFabricio Voznika
Reserve the MSB from ino for synthetic dentries to prevent conflict with regular dentries. Log warning in case MSB is set for regular dentries. Updates #1487 PiperOrigin-RevId: 319869858
2020-07-01Update preadv2/pwritev2 flag handling in vfs2.Dean Deng
We do not support RWF_SYNC/RWF_DSYNC and probably shouldn't silently accept them, since the user may incorrectly believe that we are synchronizing I/O. Remove the pwritev2 test verifying that we support these flags. gvisor.dev/issue/2601 is the tracking bug for deciding which RWF_.* flags we need and supporting them. Updates #2923, #2601. PiperOrigin-RevId: 319351286
2020-07-01[vfs2][gofer] Fix mmap syscall test.Ayush Ranjan
We were not invalidating mappings when the file size changed in shared mode. Enabled the syscall test for vfs2. Updates #2923 PiperOrigin-RevId: 319346569
2020-07-01[vfs2][gofer] Update file size to 0 on O_TRUNCAyush Ranjan
Some Open:TruncateXxx syscall tests were failing because the file size was not being updated when the file was opened with O_TRUNC. Fixes Truncate tests in test/syscalls:open_test_runsc_ptrace_vfs2. Updates #2923 PiperOrigin-RevId: 319340127
2020-07-01Port vfs1 implementation of sync_file_range to vfs2.Dean Deng
Currently, we always perform a full-file sync which could be extremely expensive for some applications. Although vfs1 did not fully support sync_file_range, there were some optimizations that allowed us skip some unnecessary write-outs. Updates #2923, #1897. PiperOrigin-RevId: 319324213
2020-07-01Port fallocate to VFS2.Zach Koopmans
PiperOrigin-RevId: 319283715
2020-06-27Support sticky bit in vfs2.Dean Deng
Updates #2923. PiperOrigin-RevId: 318648128
2020-06-26Support inotify IN_ONESHOT.Dean Deng
Also, while we're here, make sure that gofer inotify events are generated when files are created in remote revalidating mode. Updates #1479. PiperOrigin-RevId: 318536354
2020-06-23Complete inotify IN_EXCL_UNLINK implementation in VFS2.Dean Deng
Events were only skipped on parent directories after their children were unlinked; events on the unlinked file itself need to be skipped as well. As a result, all Watches.Notify() calls need to know whether the dentry where the call came from was unlinked. Updates #1479. PiperOrigin-RevId: 317979476
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
2020-06-22Check 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 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
2020-06-17Implement Sync() to directoriesFabricio Voznika
Updates #1035, #1199 PiperOrigin-RevId: 317028108
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
2020-06-09Implement 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
2020-06-05Implement 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
2020-05-29Port 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
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