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path: root/pkg/sentry/fs/dirent.go
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2020-09-09Consistent 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
2020-08-03Plumbing 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
2020-04-09Downgrade VFS1-specific FIXME to a NOTE.Jamie Liu
PiperOrigin-RevId: 305794509
2020-03-19Remove the "frozen" bit from dirents.Zach Koopmans
Frozen was to lock down changes to the host filesystem for hostFS. Now that hostFS is gone, it can be removed. PiperOrigin-RevId: 301907923
2020-02-25Fix DATA RACE in fs.MayDelete.Adin Scannell
MayDelete must lock the directory also, otherwise concurrent renames may race. Note that this also changes the methods to be aligned with the actual Remove and RemoveDirectory methods to minimize confusion when reading the code. (It was hard to see that resolution was correct.) PiperOrigin-RevId: 297258304
2020-01-27Update package locations.Adin Scannell
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
2020-01-09New sync package.Ian Gudger
* 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
2019-09-13gvisor: return ENOTDIR from the unlink syscallAndrei Vagin
ENOTDIR has to be returned when a component used as a directory in pathname is not, in fact, a directory. PiperOrigin-RevId: 269037893
2019-06-28Add finalizer on AtomicRefCount to check for leaks.Ian Gudger
PiperOrigin-RevId: 255711454
2019-06-27Cache directory entries in the overlayMichael Pratt
Currently, the overlay dirCache is only used for a single logical use of getdents. i.e., it is discard when the FD is closed or seeked back to the beginning. But the initial work of getting the directory contents can be quite expensive (particularly sorting large directories), so we should keep it as long as possible. This is very similar to the readdirCache in fs/gofer. Since the upper filesystem does not have to allow caching readdir entries, the new CacheReaddir MountSourceOperations method controls this behavior. This caching should be trivially movable to all Inodes if desired, though that adds an additional copy step for non-overlay Inodes. (Overlay Inodes already do the extra copy). PiperOrigin-RevId: 255477592
2019-06-21gvisor/fs: getdents returns 0 if offset is equal to FileMaxOffsetAndrei Vagin
FileMaxOffset is a special case when lseek(d, 0, SEEK_END) has been called. PiperOrigin-RevId: 254498777
2019-06-13Plumb context through more layers of filesytem.Ian Gudger
All functions which allocate objects containing AtomicRefCounts will soon need a context. PiperOrigin-RevId: 253147709
2019-06-13Update canonical repository.Adin Scannell
This can be merged after: https://github.com/google/gvisor-website/pull/77 or https://github.com/google/gvisor-website/pull/78 PiperOrigin-RevId: 253132620
2019-06-06Copy up parent when binding UDS on overlayfsFabricio Voznika
Overlayfs was expecting the parent to exist when bind(2) was called, which may not be the case. The fix is to copy the parent directory to the upper layer before binding the UDS. There is not good place to add tests for it. Syscall tests would be ideal, but it's hard to guarantee that the directory where the socket is created hasn't been touched before (and thus copied the parent to the upper layer). Added it to runsc integration tests for now. If it turns out we have lots of these kind of tests, we can consider moving them somewhere more appropriate. PiperOrigin-RevId: 251954156
2019-04-29Change copyright notice to "The gVisor Authors"Michael Pratt
Based on the guidelines at https://opensource.google.com/docs/releasing/authors/. 1. $ rg -l "Google LLC" | xargs sed -i 's/Google LLC.*/The gVisor Authors./' 2. Manual fixup of "Google Inc" references. 3. Add AUTHORS file. Authors may request to be added to this file. 4. Point netstack AUTHORS to gVisor AUTHORS. Drop CONTRIBUTORS. Fixes #209 PiperOrigin-RevId: 245823212 Change-Id: I64530b24ad021a7d683137459cafc510f5ee1de9
2019-04-29Allow and document bug ids in gVisor codebase.Nicolas Lacasse
PiperOrigin-RevId: 245818639 Change-Id: I03703ef0fb9b6675955637b9fe2776204c545789
2019-04-25Don't enforce NAME_MAX in fs.Dirent.walk().Jamie Liu
Maximum filename length is filesystem-dependent, and obtained via statfs::f_namelen. This limit is usually 255 bytes (NAME_MAX), but not always. For example, VFAT supports filenames of up to 255... UCS-2 characters, which Linux conservatively takes to mean UTF-8-encoded bytes: fs/fat/inode.c:fat_statfs(), FAT_LFN_LEN * NLS_MAX_CHARSET_SIZE. As a result, Linux's VFS does not enforce NAME_MAX: $ rg --maxdepth=1 '\WNAME_MAX\W' fs/ include/linux/ fs/libfs.c 38: buf->f_namelen = NAME_MAX; 64: if (dentry->d_name.len > NAME_MAX) include/linux/relay.h 74: char base_filename[NAME_MAX]; /* saved base filename */ include/linux/fscrypt.h 149: * filenames up to NAME_MAX bytes, since base64 encoding expands the length. include/linux/exportfs.h 176: * understanding that it is already pointing to a a %NAME_MAX+1 sized Remove this check from core VFS, and add it to ramfs (and by extension tmpfs), where it is actually applicable: mm/shmem.c:shmem_dir_inode_operations.lookup == simple_lookup *does* enforce NAME_MAX. PiperOrigin-RevId: 245324748 Change-Id: I17567c4324bfd60e31746a5270096e75db963fac
2019-04-10DATA RACE in fs.(*Dirent).fullNameYong He
add renameMu.Lock when oldParent == newParent in order to avoid data race in following report: WARNING: DATA RACE Read at 0x00c000ba2160 by goroutine 405: gvisor.googlesource.com/gvisor/pkg/sentry/fs.(*Dirent).fullName() pkg/sentry/fs/dirent.go:246 +0x6c gvisor.googlesource.com/gvisor/pkg/sentry/fs.(*Dirent).FullName() pkg/sentry/fs/dirent.go:356 +0x8b gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*FDMap).String() pkg/sentry/kernel/fd_map.go:135 +0x1e0 fmt.(*pp).handleMethods() GOROOT/src/fmt/print.go:603 +0x404 fmt.(*pp).printArg() GOROOT/src/fmt/print.go:686 +0x255 fmt.(*pp).doPrintf() GOROOT/src/fmt/print.go:1003 +0x33f fmt.Fprintf() GOROOT/src/fmt/print.go:188 +0x7f gvisor.googlesource.com/gvisor/pkg/log.(*Writer).Emit() pkg/log/log.go:121 +0x89 gvisor.googlesource.com/gvisor/pkg/log.GoogleEmitter.Emit() pkg/log/glog.go:162 +0x1acc gvisor.googlesource.com/gvisor/pkg/log.(*GoogleEmitter).Emit() <autogenerated>:1 +0xe1 gvisor.googlesource.com/gvisor/pkg/log.(*BasicLogger).Debugf() pkg/log/log.go:177 +0x111 gvisor.googlesource.com/gvisor/pkg/log.Debugf() pkg/log/log.go:235 +0x66 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).Debugf() pkg/sentry/kernel/task_log.go:48 +0xfe gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).DebugDumpState() pkg/sentry/kernel/task_log.go:66 +0x11f gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*runApp).execute() pkg/sentry/kernel/task_run.go:272 +0xc80 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).run() pkg/sentry/kernel/task_run.go:91 +0x24b Previous write at 0x00c000ba2160 by goroutine 423: gvisor.googlesource.com/gvisor/pkg/sentry/fs.Rename() pkg/sentry/fs/dirent.go:1628 +0x61f gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.renameAt.func1.1() pkg/sentry/syscalls/linux/sys_file.go:1864 +0x1f8 gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.fileOpAt( gvisor.googlesource.com/g/linux/sys_file.go:51 +0x20f gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.renameAt.func1() pkg/sentry/syscalls/linux/sys_file.go:1852 +0x218 gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.fileOpAt() pkg/sentry/syscalls/linux/sys_file.go:51 +0x20f gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.renameAt() pkg/sentry/syscalls/linux/sys_file.go:1840 +0x180 gvisor.googlesource.com/gvisor/pkg/sentry/syscalls/linux.Rename() pkg/sentry/syscalls/linux/sys_file.go:1873 +0x60 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).executeSyscall() pkg/sentry/kernel/task_syscall.go:165 +0x17a gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).doSyscallInvoke() pkg/sentry/kernel/task_syscall.go:283 +0xb4 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).doSyscallEnter() pkg/sentry/kernel/task_syscall.go:244 +0x10c gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).doSyscall() pkg/sentry/kernel/task_syscall.go:219 +0x1e3 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*runApp).execute() pkg/sentry/kernel/task_run.go:215 +0x15a9 gvisor.googlesource.com/gvisor/pkg/sentry/kernel.(*Task).run() pkg/sentry/kernel/task_run.go:91 +0x24b Reported-by: syzbot+e1babbf756fab380dfff@syzkaller.appspotmail.com Change-Id: Icd2620bb3ea28b817bf0672d454a22b9d8ee189a PiperOrigin-RevId: 242938741
2019-04-03Don't release d.mu in checks for child-existence.Nicolas Lacasse
Dirent.exists() is called in Create to check whether a child with the given name already exists. Dirent.exists() calls walk(), and before this CL allowed walk() to drop d.mu while calling d.Inode.Lookup. During this existence check, a racing Rename() can acquire d.mu and create a new child of the dirent with the same name. (Note that the source and destination of the rename must be in the same directory, otherwise renameMu will be taken preventing the race.) In this case, d.exists() can return false, even though a child with the same name actually does exist. This CL changes d.exists() so that it does not release d.mu while walking, thus preventing the race with Rename. It also adds comments noting that lockForRename may not take renameMu if the source and destination are in the same directory, as this is a bit surprising (at least it was to me). PiperOrigin-RevId: 241842579 Change-Id: I56524870e39dfcd18cab82054eb3088846c34813
2019-03-18Remove references to replaced child in Rename in ramfs/agentfsMichael Pratt
In the case of a rename replacing an existing destination inode, ramfs Rename failed to first remove the replaced inode. This caused: 1. A leak of a reference to the inode (making it live indefinitely). 2. For directories, a leak of the replaced directory's .. link to the parent. This would cause the parent's link count to incorrectly increase. (2) is much simpler to test than (1), so that's what I've done. agentfs has a similar bug with link count only, so the Dirent layer informs the Inode if this is a replacing rename. Fixes #133 PiperOrigin-RevId: 239105698 Change-Id: I4450af2462d8ae3339def812287213d2cbeebde0
2019-01-14Remove fs.Handle, ramfs.Entry, and all the DeprecatedFileOperations.Nicolas Lacasse
More helper structs have been added to the fsutil package to make it easier to implement fs.InodeOperations and fs.FileOperations. PiperOrigin-RevId: 229305982 Change-Id: Ib6f8d3862f4216745116857913dbfa351530223b
2018-12-05Enforce directory accessibility before delete WalkMichael Pratt
By Walking before checking that the directory is writable and executable, MayDelete may return the Walk error (e.g., ENOENT) which would normally be masked by a permission error (EACCES). PiperOrigin-RevId: 224222453 Change-Id: I108a7f730e6bdaa7f277eaddb776267c00805475
2018-12-04Enforce name length restriction on paths.Brian Geffon
NAME_LENGTH must be enforced per component. PiperOrigin-RevId: 224046749 Change-Id: Iba8105b00d951f2509dc768af58e4110dafbe1c9
2018-12-04Fix data race caused by unlocked call of Dirent.descendantOf.Nicolas Lacasse
PiperOrigin-RevId: 224025363 Change-Id: I98864403c779832e9e1436f7d3c3f6fb2fba9904
2018-10-19Use correct company name in copyright headerIan Gudger
PiperOrigin-RevId: 217951017 Change-Id: Ie08bf6987f98467d07457bcf35b5f1ff6e43c035
2018-10-17Move Unix transport out of netstackIan Gudger
PiperOrigin-RevId: 217557656 Change-Id: I63d27635b1a6c12877279995d2d9847b6a19da9b
2018-10-15Clean up Rename and Unlink checks for EBUSY.Nicolas Lacasse
- Change Dirent.Busy => Dirent.isMountPoint. The function body is unchanged, and it is no longer exported. - fs.MayDelete now checks that the victim is not the process root. This aligns with Linux's namei.c:may_delete(). - Fix "is-ancestor" checks to actually compare all ancestors, not just the parents. - Fix handling of paths that end in dots, which are handled differently in Rename vs. Unlink. PiperOrigin-RevId: 217239274 Change-Id: I7a0eb768e70a1b2915017ce54f7f95cbf8edf1fb
2018-10-15sentry: save fs.Dirent deleted info.Zhaozhong Ni
PiperOrigin-RevId: 217155458 Change-Id: Id3265b1ec784787039e2131c80254ac4937330c7
2018-09-14Make gVisor hard link check match Linux's.Nicolas Lacasse
Linux permits hard-linking if the target is owned by the user OR the target has Read+Write permission. PiperOrigin-RevId: 213024613 Change-Id: If642066317b568b99084edd33ee4e8822ec9cbb3
2018-08-29fs: Fix renameMu lock recursion.Nicolas Lacasse
dirent.walk() takes renameMu, but is often called with renameMu already held, which can lead to a deadlock. Fix this by requiring renameMu to be held for reading when dirent.walk() is called. This causes walks and existence checks to block while a rename operation takes place, but that is what we were already trying to enforce by taking renameMu in walk() anyways. PiperOrigin-RevId: 210760780 Change-Id: Id61018e6e4adbeac53b9c1b3aa24ab77f75d8a54
2018-08-29fs: Drop reference to over-written file before renaming over it.Nicolas Lacasse
dirent.go:Rename() walks to the file being replaced and defers replaced.DecRef(). After the rename, the reference is dropped, triggering a writeout and SettAttr call to the gofer. Because of lazyOpenForWrite, the gofer opens the replaced file BY ITS OLD NAME and calls ftruncate on it. This CL changes Remove to drop the reference on replaced (and thus trigger writeout) before the actual rename call. PiperOrigin-RevId: 210756097 Change-Id: I01ea09a5ee6c2e2d464560362f09943641638e0f
2018-08-28sentry: optimize dirent weakref map save / restore.Zhaozhong Ni
Weak references save / restore involves multiple interface indirection and cause material latency overhead when there are lots of dirents, each containing a weak reference map. The nil entries in the map should also be purged. PiperOrigin-RevId: 210593727 Change-Id: Ied6f4c3c0726fcc53a24b983d9b3a79121b6b758
2018-08-27fs: Fix remote-revalidate cache policy.Nicolas Lacasse
When revalidating a Dirent, if the inode id is the same, then we don't need to throw away the entire Dirent. We can just update the unstable attributes in place. If the inode id has changed, then the remote file has been deleted or moved, and we have no choice but to throw away the dirent we have a look up another. In this case, we may still end up losing a mounted dirent that is a child of the revalidated dirent. However, that seems appropriate here because the entire mount point has been pulled out from underneath us. Because gVisor's overlay is at the Inode level rather than the Dirent level, we must pass the parent Inode and name along with the Inode that is being revalidated. PiperOrigin-RevId: 210431270 Change-Id: I705caef9c68900234972d5aac4ae3a78c61c7d42
2018-08-24fs: Drop unused WaitGroup in Dirent.destroy.Nicolas Lacasse
PiperOrigin-RevId: 210182476 Change-Id: I655a2a801e2069108d30323f7f5ae76deb3ea3ec
2018-08-22fs: Hold Dirent.mu when calling Dirent.flush().Nicolas Lacasse
As required by the contract in Dirent.flush(). Also inline Dirent.freeze() into Dirent.Freeze(), since it is only called from there. PiperOrigin-RevId: 209783626 Change-Id: Ie6de4533d93dd299ffa01dabfa257c9cc259b1f4
2018-08-13Prevent renames across walk fast path.Adin Scannell
PiperOrigin-RevId: 208533436 Change-Id: Ifc1a4e2d6438a424650bee831c301b1ac0d670a3
2018-08-10fs: Allow overlays to revalidate files from the upper fs.Nicolas Lacasse
Previously, an overlay would panic if either the upper or lower fs required revalidation for a given Dirent. Now, we allow revalidation from the upper file, but not the lower. If a cached overlay inode does need revalidation (because the upper needs revalidation), then the entire overlay Inode will be discarded and a new overlay Inode will be built with a fresh copy of the upper file. As a side effect of this change, Revalidate must take an Inode instead of a Dirent, since an overlay needs to revalidate individual Inodes. PiperOrigin-RevId: 208293638 Change-Id: Ic8f8d1ffdc09114721745661a09522b54420c5f1
2018-08-10Enable checkpoint/restore in cases of UDS use.Brielle Broder
Previously, processes which used file-system Unix Domain Sockets could not be checkpoint-ed in runsc because the sockets were saved with their inode numbers which do not necessarily remain the same upon restore. Now, the sockets are also saved with their paths so that the new inodes can be determined for the sockets based on these paths after restoring. Tests for cases with UDS use are included. Test cleanup to come. PiperOrigin-RevId: 208268781 Change-Id: Ieaa5d5d9a64914ca105cae199fd8492710b1d7ec
2018-08-02Automated rollback of changelist 207037226Zhaozhong Ni
PiperOrigin-RevId: 207125440 Change-Id: I6c572afb4d693ee72a0c458a988b0e96d191cd49
2018-08-01Automated rollback of changelist 207007153Michael Pratt
PiperOrigin-RevId: 207037226 Change-Id: I8b5f1a056d4f3eab17846f2e0193bb737ecb5428
2018-08-01stateify: convert all packages to use explicit mode.Zhaozhong Ni
PiperOrigin-RevId: 207007153 Change-Id: Ifedf1cc3758dc18be16647a4ece9c840c1c636c9
2018-07-19fs: Pass context to Revalidate() function.Nicolas Lacasse
The current revalidation logic is very simple and does not do much introspection of the dirent being revalidated (other than looking at the type of file). Fancier revalidation logic is coming soon, and we need to be able to look at the cached and uncached attributes of a given dirent, and we need a context to perform some of these operations. PiperOrigin-RevId: 205307351 Change-Id: If17ea1c631d8f9489c0e05a263e23d7a8a3bf159
2018-07-18Fix lock-ordering violation in Create by logging BaseName instead of FullName.Nicolas Lacasse
Dirent.FullName takes the global renameMu, but can be called during Create, which itself takes dirent.mu and dirent.dirMu, which is a lock-order violation: Dirent.Create d.dirMu.Lock d.mu.Lock Inode.Create gofer.inodeOperations.Create gofer.NewFile Dirent.FullName d.renameMu.RLock We only use the FullName here for logging, and in this case we can get by with logging only the BaseName. A `BaseName` method was added to Dirent, which simply returns the name, taking d.parent.mu as required. In the Create pathway, we can't call d.BaseName() because taking d.parent.mu after d.mu violates the lock order. But we already know the base name of the file we just created, so that's OK. In the Open/GetFile pathway, we are free to call d.BaseName() because the other dirent locks are not held. PiperOrigin-RevId: 205112278 Change-Id: Ib45c734081aecc9b225249a65fa8093eb4995f10
2018-07-02Hold d.parent.mu when reading d.nameMichael Pratt
PiperOrigin-RevId: 203041657 Change-Id: I120783d91712818e600505454c9276f8d9877f37
2018-06-25Fix panic messageMichael Pratt
The arguments are backwards from the message. PiperOrigin-RevId: 202054887 Change-Id: Id5750a84ca091f8b8fbe15be8c648d4fa3e31eb2
2018-06-13Fix reference leak in VDSO validationIan Gudger
PiperOrigin-RevId: 200496070 Change-Id: I33adb717c44e5b4bcadece882be3ab1ee3920556
2018-06-12Fix reference leak for negative direntsIan Gudger
PiperOrigin-RevId: 200306715 Change-Id: I7c80059c77ebd3d9a5d7d48b05c8e7a597f10850
2018-04-28Check in gVisor.Googler
PiperOrigin-RevId: 194583126 Change-Id: Ica1d8821a90f74e7e745962d71801c598c652463
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