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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
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- 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
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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
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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
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Limited to tmpfs. Inotify support in other filesystem implementations to
follow.
Updates #1479
PiperOrigin-RevId: 313828648
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PiperOrigin-RevId: 313817646
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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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Updates #1197, #1198, #1672
PiperOrigin-RevId: 310432006
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Implement PrependPath() in host.filesystem to correctly format
name for host files.
Updates #1672
PiperOrigin-RevId: 309959135
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This allows for kerfs.Filesystem to be overridden by
different implementations.
Updates #1672
PiperOrigin-RevId: 309809321
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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
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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
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PiperOrigin-RevId: 308304793
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- 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
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PiperOrigin-RevId: 308164359
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- 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
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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
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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
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PiperOrigin-RevId: 305592245
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Updates #1195
PiperOrigin-RevId: 305143567
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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
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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
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BoundEndpointAt() is needed to support Unix sockets bound at a
file path, corresponding to BoundEndpoint() in VFS1.
Updates #1476.
PiperOrigin-RevId: 303258251
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Updates #1035
PiperOrigin-RevId: 303021328
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Updates #1035
PiperOrigin-RevId: 301255357
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Only gofer filesystem was calling vfs.CheckSetStat for
vfs.FilesystemImpl.SetStatAt and vfs.FileDescriptionImpl.SetStat.
Updates #1193, #1672, #1197
PiperOrigin-RevId: 301226522
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Updates #1195, #1193
PiperOrigin-RevId: 300950993
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Closes #1195
PiperOrigin-RevId: 300867055
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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
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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
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This is easier than storing errors from e.g. CopyOut in the callback.
PiperOrigin-RevId: 295230021
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This saves one pointer dereference per VFS access.
Updates #1623
PiperOrigin-RevId: 295216176
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- 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
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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
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PiperOrigin-RevId: 294272755
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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
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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
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PiperOrigin-RevId: 291745021
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PiperOrigin-RevId: 291041576
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PiperOrigin-RevId: 291006713
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PiperOrigin-RevId: 290822487
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Files not implemented require VFSv2 plumbing into the kernel.
Also, cgroup is not implemented yet.
Updates #1195
PiperOrigin-RevId: 290129176
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Except for one under /proc/sys/net/ipv4/tcp_sack.
/proc/pid/* is still incomplete.
Updates #1195
PiperOrigin-RevId: 290120438
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* 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
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- 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
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Updates #1195
PiperOrigin-RevId: 287269106
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Updates #1195
PiperOrigin-RevId: 287227722
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It was calling Dentry.InsertChild with the dentry's mutex
already locked.
Updates #1035
PiperOrigin-RevId: 286962742
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- Make FilesystemImpl methods that operate on parent directories require
!rp.Done() (i.e. there is at least one path component to resolve) as
precondition and postcondition (in cases where they do not finish path
resolution due to mount boundary / absolute symlink), and require that they
do not need to follow the last path component (the file being created /
deleted) as a symlink. Check for these in VFS.
- Add FilesystemImpl.GetParentDentryAt(), which is required to obtain the old
parent directory for VFS.RenameAt(). (Passing the Dentry to be renamed
instead has the wrong semantics if the file named by the old path is a mount
point since the Dentry will be on the wrong Mount.)
- Update memfs to implement these methods correctly (?), including RenameAt.
- Change fspath.Parse() to allow empty paths (to simplify implementation of
AT_EMPTY_PATH).
- Change vfs.PathOperation to take a fspath.Path instead of a raw pathname;
non-test callers will need to fspath.Parse() pathnames themselves anyway in
order to detect absolute paths and select PathOperation.Start accordingly.
PiperOrigin-RevId: 286934941
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PiperOrigin-RevId: 286616668
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