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2020-10-28Add leak checking for kernfs.Dentry.Dean Deng
Updates #1486. PiperOrigin-RevId: 339581879
2020-10-23[vfs] kernfs: Implement remaining InodeAttr fields.Ayush Ranjan
Added the following fields in kernfs.InodeAttr: - blockSize - atime - mtime - ctime Also resolved all TODOs for #1193. Fixes #1193 PiperOrigin-RevId: 338714527
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
2020-09-24[vfs] [2/2] kernfs: kernfs: Internally use kernfs.Dentry instead of vfs.Dentry.Ayush Ranjan
Update signatures for: - All methods in inodeDirectory - deferDecRef() and Filesystem.droppedDentries - newSyntheticDirectory() - `slot`s used in OrderedChildren and subsequent methods like replaceChildLocked() and checkExistingLocked() - stepExistingLocked(), walkParentDirLocked(), checkCreateLocked() Updates #1193 PiperOrigin-RevId: 333558866
2020-09-24Add basic stateify annotations.Adin Scannell
Updates #1663 PiperOrigin-RevId: 333539293
2020-09-23fuse: don't call dentry.InsertChildAndrei Vagin
It is called from the kernfs code (OpenAt and revalidateChildLocked()). For RemoveChildLocked, it is opposed. We need to call it from fuse.RmDir and fuse.Unlink. PiperOrigin-RevId: 333453218
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
2020-09-21Use kernfs.Dentry for kernfs.Lookup.Dean Deng
Updates #1193. PiperOrigin-RevId: 332939026
2020-09-18Merge pull request #3972 from btw616:fix/commentsgVisor bot
PiperOrigin-RevId: 332486111
2020-09-17fuse.DeviceFD needs to hold a reference on the associated filesystem.Rahat Mahmood
This fixes a use-after-free in fuse.DeviceFD.Release. PiperOrigin-RevId: 332394146
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>
2020-09-16fuse: fix data race in fusefs Release()Jinmou Li
fix #3956
2020-09-16fuse: fix FUSE_RELEASE reply handlingJinmou Li
fix #3963
2020-09-16Fix FUSE connection control lock ordering and race in unit testJinmou Li
2020-09-16fuse: don't pass lock by valueAndrei Vagin
copylocks: directory.go:34:7: Allocate passes lock by value: fuse/fuse.directoryFD contains fuse/fuse.fileDescription contains pkg/sentry/vfs/vfs.FileDescription contains pkg/sync/sync.Mutex
2020-09-16Fix FUSE unit test after vfs interface changeJinmou Li
2020-09-16Fix FUSE go unit test merge conflict mistakeJinmou Li
2020-09-16fs/fuse: Move the 'marshal' and 'primitive' packages to the 'pkg' directory.Andrei Vagin
2020-09-16Unexport fusefs.inode.nodeIDCraig Chi
2020-09-16Implement FUSE_UNLINKBoyuan He
Fixes #3696
2020-09-16Fix comments of TODO issues.Craig Chi
2020-09-16Add FUSE umount supportJinmou Li
This change implements Release for the FUSE filesystem and expected behaviors of the FUSE devices. It includes several checks for aborted connection in the path for making a request and a function to abort all the ongoing FUSE requests in order.
2020-09-16Fix FUSE_RELEASE protocol reply processingJinmou Li
This commit fixes the potential unexpected errors of original handling of FUSE_RELEASE responses while keep the same behavior (ignoring any reply).
2020-09-16Improve FUSE async/noreply call logicJinmou Li
This change adds bookkeeping variables for the FUSE request. With them, old insecure confusing code we used to process async requests is replaced by new clear compiling ones. Future code can take advantage of them to have better control of each requests.
2020-09-16Refactor FUSE connection for readability and structureJinmou Li
This change decouples the code that is weakly tied to the connection struct from connection.go, rename variables and files with more meaningful choices, adds detailed comments, explains lock orders, and adds other minor improvement to make the existing FUSE code more readable and more organized. Purpose is to avoid too much code in one file and provide better structure for the future commits.
2020-09-16Implement FUSE_SETATTRCraig Chi
This commit implements FUSE_SETATTR command. When a system call modifies the metadata of a regular file or a folder by chown(2), chmod(2), truncate(2), utime(2), or utimes(2), they should be translated to corresponding FUSE_SETATTR command and sent to the FUSE server. Fixes #3332
2020-09-16Add fh support for revise attr and fstat(2) testCraig Chi
According to Linux 4.4's FUSE behavior, the flags and fh attributes in FUSE_GETATTR are only used in read, write, and lseek. fstat(2) doesn't use them either. Add tests to ensure the requests sent from FUSE module are consistent with Linux's. Updates #3655
2020-09-16Implement FUSE_WRITEJinmou Li
This commit adds basic write(2) support for FUSE.
2020-09-16Implement FUSE_CREATECraig Chi
FUSE_CREATE is called when issuing creat(2) or open(2) with O_CREAT. It creates a new file on the FUSE filesystem. Fixes #3825
2020-09-16FUSE device: clean up readLockedJinmou Li
This change removes the unnecessary loop and avoids the recursive call. It also fixes minor bugs in this function.
2020-09-16Downgrade FUSE minor version support and clarify commentsJinmou Li
2020-09-16fuse: remove unused marshalling functionsCraig Chi
This commit removes unused marshalling functions in linux abi package and moves self-defined FUSEInitRes wrapper to fuse package. Updates #3707
2020-09-16Support multiple FUSE kernel versions of FUSE_INIT response structCraig Chi
The fuse_init_out struct changes in different FUSE kernel versions. A FUSE server may implement older versions of fuse_init_out, but they share common attributes from the beginning. Implement variable-length marshallable interface to support older versions of ABI. Fixes #3707
2020-09-16Implementing inode.GetlinkCraig Chi
kernfs uses inode.Getlink to resolve symlink when look up paths. Updates #3452
2020-09-16Fix FUSE_READDIR offset issueCraig Chi
According to readdir(3), the offset attribute in struct dirent is the offset to the next dirent instead of the offset of itself. Send the successive FUSE_READDIR requests with the offset retrieved from the last entry. Updates #3255
2020-09-16fuse: use safe go_marshal API for FUSERidwan Sharif
Until #3698 is resolved, this change is needed to ensure we're not corrupting memory anywhere.
2020-09-16fuse: Implement IterDirents for directory file descriptionRidwan Sharif
Fixes #3255. This change adds support for IterDirents. You can now use `ls` in the FUSE sandbox. Co-authored-by: Craig Chi <craigchi@google.com>
2020-09-16Implement FUSE_RMDIRRidwan Sharif
Fixes #3587 Co-authored-by: Craig Chi <craigchi@google.com>
2020-09-16Implement FUSE_READJinmou Li
Fixes #3206
2020-09-16Implement FUSE_MKDIRBoyuan He
Fixes #3392
2020-09-16Implement FUSE_READLINKBoyuan He
Fixes #3316
2020-09-16Implement FUSE_SYMLINKBoyuan He
Fixes #3452
2020-09-16Implement FUSE_MKNODBoyuan He
Fixes #3492
2020-09-16Implement FUSE_RELEASE/RELEASEDIRBoyuan He
Fixes #3314
2020-09-16Implement FUSE_OPEN/OPENDIRBoyuan He
Fixes #3174
2020-09-16Implement FUSE_LOOKUPAndrei Vagin
Fixes #3231 Co-authored-by: Boyuan He <heboyuan@google.com>
2020-09-16Extend integration test to test sequence of FUSE operationCraig Chi
Original FUSE integration test has limited capabilities. To test more situations, the new integration test framework introduces a protocol to communicate between testing thread and the FUSE server. In summary, this change includes: 1. Remove CompareResult() and break SetExpected() into SetServerResponse() and GetServerActualRequest(). We no longer set up an expected request because we want to retrieve the actual FUSE request made to the FUSE server and check in the testing thread. 2. Declare a serial buffer data structure to save the received requests and expected responses sequentially. The data structure contains a cursor to indicate the progress of accessing. This change makes sequential SetServerResponse() and GetServerActualRequest() possible. 3. Replace 2 single directional pipes with 1 bi-directional socketpair. A protocol which starts with FuseTestCmd is used between the testing thread and the FUSE server to provide various functionality. Fixes #3405
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