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2020-11-13Have fuse.DeviceFD hold reference on fuse.filesystem.Jamie Liu
This is actually just b/168751672 again; cl/332394146 was incorrectly reverted by cl/341411151. Document the reference holder to reduce the likelihood that this happens again. Also document a few other bugs observed in the process. PiperOrigin-RevId: 342339144
2020-11-13fs/tmpfs: change regularFile.size atomicallyAndrei Vagin
PiperOrigin-RevId: 342221309
2020-11-13fs/tmpfs: use atomic operations to access inode.modeAndrei Vagin
PiperOrigin-RevId: 342214859
2020-11-12Fix misuses of kernel.Task as context.Context.Jamie Liu
kernel.Task can only be used as context.Context by that Task's task goroutine. This is violated in at least two places: - In any case where one thread accesses the /proc/[tid] of any other thread, passing the kernel.Task for [tid] as the context.Context is incorrect. - Task.rebuildTraceContext() may be called by Kernel.RebuildTraceContexts() outside the scope of any task goroutine. Fix these (as well as a data race on Task.traceContext discovered during the course of finding the latter). PiperOrigin-RevId: 342174404
2020-11-12Add children names into verity hashChong Cai
children names map can be used to verify whether a child is expected during walking, so that we can detect unexpected modifications that deleted/renamed both the target file and the corresponding merkle tree file. PiperOrigin-RevId: 342170715
2020-11-12Rename kernel.TaskContext to kernel.TaskImage.Jamie Liu
This reduces confusion with context.Context (which is also relevant to kernel.Tasks) and is consistent with existing function kernel.LoadTaskImage(). PiperOrigin-RevId: 342167298
2020-11-12Filter dentries with non-zero refs in VFS2 gofer/overlay checks.Jamie Liu
PiperOrigin-RevId: 342161204
2020-11-11Read fsimpl/tmpfs timestamps atomically.Jamie Liu
PiperOrigin-RevId: 341982672
2020-11-09Print a debug message if /sys/kernel/debug/kcov is availableAndrei Vagin
This will help to debug: https://syzkaller.appspot.com/bug?id=0d717bd7028dceeb4b38f09aab2841c398b41d81 PiperOrigin-RevId: 341458715
2020-11-09Initialize references with a value of 1.Dean Deng
This lets us avoid treating a value of 0 as one reference. All references using the refsvfs2 template must call InitRefs() before the reference is incremented/decremented, or else a panic will occur. Therefore, it should be pretty easy to identify missing InitRef calls during testing. Updates #1486. PiperOrigin-RevId: 341411151
2020-11-06Allow VFS2 gofer.dentries to have separate read and write FDs.Jamie Liu
This is necessary to allow writes to files opened with O_WRONLY to go through host FDs. PiperOrigin-RevId: 341174509
2020-11-06[vfs] Return EEXIST when file already exists and rp.MustBeDir() is true.Ayush Ranjan
This is consistent with what Linux does. This was causing a PHP runtime test failure. Fixed it for VFS2. PiperOrigin-RevId: 341155209
2020-11-06[vfs] overlayfs: Do not unlink non-existing whiteout during file creation.Ayush Ranjan
We can reuse information about whether a whiteout exists on a given file path from stepLocked when creating a file at that path. This helps save an Unlink call to the upper filesystem if the whiteout does NOT exist (common case). Plumbs this information from lookupLocked() -> getChildLocked() -> stepLocked(). This also helped save a Lookup in RenameAt(). Fixes #1199 PiperOrigin-RevId: 341105351
2020-11-06Avoid extra DecRef on kernfs root for "kept" dentries.Dean Deng
The root dentry was not created through Inode.Lookup, so we should not release a reference even if inode.Keep() is true. PiperOrigin-RevId: 341103220
2020-11-03Fix more nogo testsTing-Yu Wang
PiperOrigin-RevId: 340536306
2020-11-03Make pipe min/max sizes match linux.Nicolas Lacasse
The default pipe size already matched linux, and is unchanged. Furthermore `atomicIOBytes` is made a proper constant (as it is in Linux). We were plumbing usermem.PageSize everywhere, so this is no functional change. PiperOrigin-RevId: 340497006
2020-11-02[vfs2] Refactor kernfs checkCreateLocked.Dean Deng
Don't return the filename, since it can already be determined by the caller. This was causing a panic in RenameAt, which relied on the name to be nonempty even if the error was EEXIST. Reported-by: syzbot+e9f117d000301e42361f@syzkaller.appspotmail.com PiperOrigin-RevId: 340381946
2020-11-02Pass hashing algorithms in verity fs optsChong Cai
PiperOrigin-RevId: 340275942
2020-10-30Adjust error handling in kernfs rename.Dean Deng
Read-only directories (e.g. under /sys, /proc) should return EPERM for rename. PiperOrigin-RevId: 339979022
2020-10-30Fix rename error handling for VFS2 kernfs.Dean Deng
The non-errno error was causing panics before. PiperOrigin-RevId: 339969348
2020-10-28Add leak checking for kernfs.Dentry.Dean Deng
Updates #1486. PiperOrigin-RevId: 339581879
2020-10-28Add logging option to leak checker.Dean Deng
Also refactor the template and CheckedObject interface to make this cleaner. Updates #1486. PiperOrigin-RevId: 339577120
2020-10-28Invalidate overlay.dentry.dirents during open() file creation.Jamie Liu
Updates #1199 PiperOrigin-RevId: 339528827
2020-10-28[vfs] Refactor hostfs mmap into kernfs util.Ayush Ranjan
PiperOrigin-RevId: 339505487
2020-10-27Add SHA512 to merkle tree libraryChong Cai
PiperOrigin-RevId: 339377254
2020-10-27Implement /proc/[pid]/memLennart
This PR implements /proc/[pid]/mem for `pkg/sentry/fs` (refer to #2716) and `pkg/sentry/fsimpl`. @majek COPYBARA_INTEGRATE_REVIEW=https://github.com/google/gvisor/pull/4060 from lnsp:proc-pid-mem 2caf9021254646f441be618a9bb5528610e44d43 PiperOrigin-RevId: 339369629
2020-10-27Assign VFS2 overlay device numbers based on layer device numbers.Jamie Liu
In VFS1's overlayfs, files use the device and inode number of the lower layer inode if one exists, and the upper layer inode otherwise. The former behavior is inefficient (requiring lower layer lookups even if the file exists and is otherwise wholly determined by the upper layer), and somewhat dangerous if the lower layer is also observable (since both the overlay and lower layer file will have the same device and inode numbers and thus appear to be the same file, despite being behaviorally different). VFS2 overlayfs imitates Linux overlayfs (in its default configuration) instead; it always uses the inode number from the originating layer, but synthesizes a unique device number for directories and another device number for non-directory files that have not been copied-up. As it turns out, the latter is insufficient (in VFS2, and possibly Linux as well), because a given layer may include files with different device numbers. If two distinct files on such a layer have device number X and Y respectively, but share inode number Z, then the overlay will map both files to some private device number X' and inode number Z, potentially confusing applications. Fix this by assigning synthetic device numbers based on the lower layer's device number, rather than the lower layer's vfs.Filesystem. PiperOrigin-RevId: 339300341
2020-10-26Add verity tests for deleted/renamed casesChong Cai
Also change verity test to use a context with an active task. This is required to delete/rename the file in the underlying file system. PiperOrigin-RevId: 339146445
2020-10-26[vfs] kernfs: Implement LRU cache for kernfs dentries.Ayush Ranjan
Much like the VFS2 gofer client, kernfs too now caches dentries. The size of the LRU cache is configurable via mount options. Have adopted the same reference semantics from gofer client dentry. Only sysfs and procfs use this LRU cache. The rest of the kernfs users (devpts, fusefs, host, pipefs, sockfs) still use the no cache approach. PiperOrigin-RevId: 339139835
2020-10-24Implement Seek in verity fsChong Cai
PiperOrigin-RevId: 338847417
2020-10-24Add leak checking to vfs2 structures that cannot use the refs_vfs2 template.Dean Deng
Updates #1486. PiperOrigin-RevId: 338832085
2020-10-23Internal change.Chong Cai
PiperOrigin-RevId: 338798433
2020-10-23Support VFS2 save/restore.Jamie Liu
Inode number consistency checks are now skipped in save/restore tests for reasons described in greatest detail in StatTest.StateDoesntChangeAfterRename. They pass in VFS1 due to the bug described in new test case SimpleStatTest.DifferentFilesHaveDifferentDeviceInodeNumberPairs. Fixes #1663 PiperOrigin-RevId: 338776148
2020-10-23[vfs] kernfs: cleanup/refactor.Ayush Ranjan
PiperOrigin-RevId: 338728070
2020-10-23Implement Read in gvisor verity fsChong Cai
Read is implemented by PRead, with offset obtained from Seek. PiperOrigin-RevId: 338718587
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
2020-10-23Check for verity file/Merkle file when reopenChong Cai
Even if the child dentry has been cached, we should still check whether the file and the corresponding Merkle tree file exist as expected. This ensures that we can detect deletion/renaming of files that have been previous enabled and opened. Also make all verification failures to return EIO. This helps to test verify failures. PiperOrigin-RevId: 338709055
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
2020-10-19Fix reference counting on kcov mappings.Dean Deng
Reported-by: syzbot+078580ce5dd6d607fcd8@syzkaller.appspotmail.com Reported-by: syzbot+2096681f6891e7bf8aed@syzkaller.appspotmail.com PiperOrigin-RevId: 337973519
2020-10-19Fix runsc tests on VFS2 overlay.Jamie Liu
- Check the sticky bit in overlay.filesystem.UnlinkAt(). Fixes StickyTest.StickyBitPermDenied. - When configuring a VFS2 overlay in runsc, copy the lower layer's root owner/group/mode to the upper layer's root (as in the VFS1 equivalent, boot.addOverlay()). This makes the overlay root owned by UID/GID 65534 with mode 0755 rather than owned by UID/GID 0 with mode 01777. Fixes CreateTest.CreateFailsOnUnpermittedDir, which assumes that the test cannot create files in /. - MknodTest.UnimplementedTypesReturnError assumes that the creation of device special files is not supported. However, while the VFS2 gofer client still doesn't support device special files, VFS2 tmpfs does, and in the overlay test dimension mknod() targets a tmpfs upper layer. The test initially has all capabilities, including CAP_MKNOD, so its creation of these files succeeds. Constrain these tests to VFS1. - Rename overlay.nonDirectoryFD to overlay.regularFileFD and only use it for regular files, using the original FD for pipes and device special files. This is more consistent with Linux (which gets the original inode_operations, and therefore file_operations, for these file types from ovl_fill_inode() => init_special_inode()) and fixes remaining mknod and pipe tests. - Read/write 1KB at a time in PipeTest.Streaming, rather than 4 bytes. This isn't strictly necessary, but it makes the test less obnoxiously slow on ptrace. Fixes #4407 PiperOrigin-RevId: 337971042
2020-10-19[vfs2] Fix fork reference leaks.Dean Deng
PiperOrigin-RevId: 337919424
2020-10-15Change verity isEnable to be a member of dentryChong Cai
PiperOrigin-RevId: 337384146
2020-10-13Don't read beyond EOF when inserting into sentry page cache.Jamie Liu
The sentry page cache stores file contents at page granularity; this is necessary for memory mappings. Thus file offset ranges passed to fsutil.FileRangeSet.Fill() must be page-aligned. If the read callback passed to Fill() returns (partial read, nil error) when reading up to EOF (which is the case for p9.ClientFile.ReadAt() since 9P's Rread cannot convey both a partial read and EOF), Fill() will re-invoke the read callback to try to read from EOF to the end of the containing page, which is harmless but needlessly expensive. Fix this by handling file size explicitly in fsutil.FileRangeSet.Fill(). PiperOrigin-RevId: 336934075
2020-10-13[vfs2] Don't take reference in Task.MountNamespaceVFS2 and MountNamespace.Root.Dean Deng
This fixes reference leaks related to accidentally forgetting to DecRef() after calling one or the other. PiperOrigin-RevId: 336918922
2020-10-13[vfs2] Destroy all tmpfs files when the filesystem is released.Dean Deng
In addition to fixing reference leaks, this change also releases memory used by regular tmpfs files once the containing filesystem is released. PiperOrigin-RevId: 336833111
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
2020-10-12Change verity mu to be per file systemChong Cai
verity Mu should be per file system instead of global, so that enabling and verifying in different file systems won't block each other. Also Lock verity Mu in PRead. PiperOrigin-RevId: 336779356
2020-10-12Change Merkle tree library to use ReaderAtChong Cai
Merkle tree library was originally using Read/Seek to access data and tree, since the parameters are io.ReadSeeker. This could cause race conditions if multiple threads accesses the same fd to read. Here we change to use ReaderAt, and implement it with PRead to make it thread safe. PiperOrigin-RevId: 336779260
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
2020-10-09Include stat in Verity hashChong Cai
PiperOrigin-RevId: 336395445
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