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2020-10-23Rewrite reference leak checker without finalizers.Dean Deng
Our current reference leak checker uses finalizers to verify whether an object has reached zero references before it is garbage collected. There are multiple problems with this mechanism, so a rewrite is in order. With finalizers, there is no way to guarantee that a finalizer will run before the program exits. When an unreachable object with a finalizer is garbage collected, its finalizer will be added to a queue and run asynchronously. The best we can do is run garbage collection upon sandbox exit to make sure that all finalizers are enqueued. Furthermore, if there is a chain of finalized objects, e.g. A points to B points to C, garbage collection needs to run multiple times before all of the finalizers are enqueued. The first GC run will register the finalizer for A but not free it. It takes another GC run to free A, at which point B's finalizer can be registered. As a result, we need to run GC as many times as the length of the longest such chain to have a somewhat reliable leak checker. Finally, a cyclical chain of structs pointing to one another will never be garbage collected if a finalizer is set. This is a well-known issue with Go finalizers (https://github.com/golang/go/issues/7358). Using leak checking on filesystem objects that produce cycles will not work and even result in memory leaks. The new leak checker stores reference counted objects in a global map when leak check is enabled and removes them once they are destroyed. At sandbox exit, any remaining objects in the map are considered as leaked. This provides a deterministic way of detecting leaks without relying on the complexities of finalizers and garbage collection. This approach has several benefits over the former, including: - Always detects leaks of objects that should be destroyed very close to sandbox exit. The old checker very rarely detected these leaks, because it relied on garbage collection to be run in a short window of time. - Panics if we forgot to enable leak check on a ref-counted object (we will try to remove it from the map when it is destroyed, but it will never have been added). - Can store extra logging information in the map values without adding to the size of the ref count struct itself. With the size of just an int64, the ref count object remains compact, meaning frequent operations like IncRef/DecRef are more cache-efficient. - Can aggregate leak results in a single report after the sandbox exits. Instead of having warnings littered in the log, which were non-deterministically triggered by garbage collection, we can print all warning messages at once. Note that this could also be a limitation--the sandbox must exit properly for leaks to be detected. Some basic benchmarking indicates that this change does not significantly affect performance when leak checking is enabled, which is understandable since registering/unregistering is only done once for each filesystem object. Updates #1486. PiperOrigin-RevId: 338685972
2020-10-13[vfs2] Add FilesystemType.Release to avoid reference leaks.Dean Deng
Singleton filesystem like devpts and devtmpfs have a single filesystem shared among all mounts, so they acquire a "self-reference" when initialized that must be released when the entire virtual filesystem is released at sandbox exit. PiperOrigin-RevId: 336828852
2020-10-12[vfs] kernfs: Fix inode memory leak issue.Ayush Ranjan
This change aims to fix the memory leak issue reported in #3933. Background: VFS2 kernfs kept accumulating invalid dentries if those dentries were not walked on. After substantial consideration of the problem by our team, we decided to have an LRU cache solution. This change is the first part to that solution, where we don't cache anything. The LRU cache can be added on top of this. What has changed: - Introduced the concept of an inode tree in kernfs.OrderedChildren. This is helpful is cases where the lifecycle of an inode is different from that of a dentry. - OrderedChildren now deals with initialized inodes instead of initialized dentries. It now implements Lookup() where it constructs a new dentry using the inode. - OrderedChildren holds a ref on all its children inodes. With this change, now an inode can "outlive" a dentry pointing to it. See comments in kernfs.OrderedChildren. - The kernfs dentry tree is solely maintained by kernfs only. Inode implementations can not modify the dentry tree. - Dentries that reach ref count 0 are removed from the dentry tree. - revalidateChildLocked now defer-DecRefs the newly created dentry from Inode.Lookup(), limiting its life to the current filesystem operation. If refs are picked on the dentry during the FS op (via an FD or something), then it will stick around and will be removed when the FD is closed. So there is essentially _no caching_ for Look()ed up dentries. - kernfs.DecRef does not have the precondition that fs.mu must be locked. Fixes #3933 PiperOrigin-RevId: 336768576
2020-09-30Merge pull request #3824 from btw616:fix/issue-3823gVisor bot
PiperOrigin-RevId: 334721453
2020-09-24Add basic stateify annotations.Adin Scannell
Updates #1663 PiperOrigin-RevId: 333539293
2020-09-23[vfs] kernfs: Enable leak checking consistently.Ayush Ranjan
There were some instances where we were not enabling leak checking. PiperOrigin-RevId: 333418571
2020-09-22[vfs] [1/2] kernfs: Internally use kernfs.Dentry instead of vfs.Dentry.Ayush Ranjan
Update signatures for: - walkExistingLocked - checkDeleteLocked - Inode.Open Updates #1193 PiperOrigin-RevId: 333163381
2020-09-18Merge pull request #3972 from btw616:fix/commentsgVisor bot
PiperOrigin-RevId: 332486111
2020-09-17Complete vfs2 implementation of fallocate.Dean Deng
This change includes overlay, special regular gofer files, and hostfs. Fixes #3589. PiperOrigin-RevId: 332330860
2020-09-17fsimpl: improve the "implements" commentsTiwei Bie
As noticed by @ayushr2, the "implements" comments are not consistent, e.g. // IterDirents implements kernfs.inodeDynamicLookup. // Generate implements vfs.DynamicBytesSource.Generate. This patch improves this by making the comments like this consistently include the package name (when the interface and struct are not in the same package) and method name. Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
2020-09-11Move the 'marshal' and 'primitive' packages to the 'pkg' directory.Rahat Mahmood
PiperOrigin-RevId: 331256608
2020-09-11Fix host unix socket to not swallow EOF incorrectly.Bhasker Hariharan
Fixes an error where in case of a receive buffer larger than the host send buffer size for a host backed unix dgram socket we would end up swallowing EOF from recvmsg syscall causing the read() to block forever. PiperOrigin-RevId: 331192810
2020-09-01Refactor tty codebase to use master-replica terminology.Ayush Ranjan
Updates #2972 PiperOrigin-RevId: 329584905
2020-09-01fsimpl/host: fix the order of removing FD notifierTiwei Bie
FD notifier should be removed before we close the FD, otherwise there will be race condition that another FD which has the same value is opened and added before the existing FD notifier is removed. Fixes: #3823 Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
2020-08-28Implement StatFS for various VFS2 filesystems.Rahat Mahmood
This mainly involved enabling kernfs' client filesystems to provide a StatFS implementation. Fixes #3411, #3515. PiperOrigin-RevId: 329009864
2020-08-25[go-marshal] Enable auto-marshalling for host tty.Ayush Ranjan
PiperOrigin-RevId: 328415633
2020-08-20Add reference count checking to the fsimpl/host package.Dean Deng
Includes a minor refactor for inode construction. Updates #1486. PiperOrigin-RevId: 327694933
2020-08-18Get rid of kernfs.Inode.Destroy.Dean Deng
This interface method is unneeded. PiperOrigin-RevId: 327370325
2020-08-18Move ERESTART* error definitions to syserror package.Dean Deng
This is needed to avoid circular dependencies between the vfs and kernel packages. PiperOrigin-RevId: 327355524
2020-08-12Redirect TODOFabricio Voznika
Fixes #2923 PiperOrigin-RevId: 326296589
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
2020-07-15Merge pull request #3236 from craig08:fuse-kernfs-inode-stat-add-ctxgVisor bot
PiperOrigin-RevId: 321496734
2020-07-15fdbased: Vectorized write for packet; relax writev syscall filter.Ting-Yu Wang
Now it calls pkt.Data.ToView() when writing the packet. This may require copying when the packet is large, which puts the worse case in an even worse situation. This sent out in a separate preparation change as it requires syscall filter changes. This change will be followed by the change for the adoption of the new PacketHeader API. PiperOrigin-RevId: 321447003
2020-07-14Include context in kernfs.Inode.Stat methodCraig Chi
To implement stat(2) in FUSE, we have to embed credentials and pid in request header. The information should be extracted from the context passed to VFS layer. Therefore `Stat()` signature in `kernfs.Inode` interface should include context as first argument. Some other fs implementations need to be modified as well, such as devpts, host, pipefs, and proc. Fixes #3235
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
2020-07-01Remove maxSendBufferSize from vfs2.Dean Deng
Complements cl/315991648. PiperOrigin-RevId: 319327853
2020-07-01Port fallocate to VFS2.Zach Koopmans
PiperOrigin-RevId: 319283715
2020-06-23Clean up hostfs TODOs.Dean Deng
This CL does a handful of things: - Support O_DSYNC, O_SYNC - Support O_APPEND and document an unavoidable race condition - Ignore O_DIRECT; we probably don't want to allow applications to set O_DIRECT on the host fd itself. - Leave a TODO for supporting O_NONBLOCK, which is a simple fix once RWF_NOWAIT is supported. - Get rid of caching TODO; force_page_cache is not configurable for host fs in vfs1 or vfs2 after whitelist fs was removed. - For the remaining TODOs, link to more specific bugs. Fixes #1672. PiperOrigin-RevId: 317985269
2020-06-22Only allow regular files, sockets, pipes, and char devices to be imported.Dean Deng
PiperOrigin-RevId: 317796028
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
2020-06-09Implement 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
2020-05-20Move 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
2020-05-11Add 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
2020-05-05Return correct name for imported host filesFabricio Voznika
Implement PrependPath() in host.filesystem to correctly format name for host files. Updates #1672 PiperOrigin-RevId: 309959135
2020-05-04Add TTY support on VFS2 to runscFabricio Voznika
Updates #1623, #1487 PiperOrigin-RevId: 309777922
2020-05-01Port netstack, hostinet, and netlink sockets to VFS2.Dean Deng
All three follow the same pattern: 1. Refactor VFS1 sockets into socketOpsCommon, so that most of the methods can be shared with VFS2. 2. Create a FileDescriptionImpl with the corresponding socket operations, rewriting the few that cannot be shared with VFS1. 3. Set up a VFS2 socket provider that creates a socket by setting up a dentry in the global Kernel.socketMount and connecting it with a new FileDescription. This mostly completes the work for porting sockets to VFS2, and many syscall tests can be enabled as a result. There are several networking-related syscall tests that are still not passing: 1. net gofer tests 2. socketpair gofer tests 2. sendfile tests (splice is not implemented in VFS2 yet) Updates #1478, #1484, #1485 PiperOrigin-RevId: 309457331
2020-04-30Implement waiter.Waitable methods on VFS2 host inodes.Nicolas Lacasse
This fixes bash in Ubuntu. Updates #1672. PiperOrigin-RevId: 309298252
2020-04-27Import host sockets.Dean Deng
The FileDescription implementation for hostfs sockets uses the standard Unix socket implementation (unix.SocketVFS2), but is also tied to a hostfs dentry. Updates #1672, #1476 PiperOrigin-RevId: 308716426
2020-04-24Port SCM Rights to VFS2.Dean Deng
Fixes #1477. PiperOrigin-RevId: 308317511
2020-04-24Plumb context.Context into kernfs.Inode.Open().Dean Deng
PiperOrigin-RevId: 308304793
2020-04-24Move hostfs mount to Kernel struct.Dean Deng
This is needed to set up host fds passed through a Unix socket. Note that the host package depends on kernel, so we cannot set up the hostfs mount directly in Kernel.Init as we do for sockfs and pipefs. Also, adjust sockfs to make its setup look more like hostfs's and pipefs's. PiperOrigin-RevId: 308274053
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