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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
2020-10-23Rewrite 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
2020-10-08Implement MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ.Jamie Liu
cf. 2a36ab717e8f "rseq/membarrier: Add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ" PiperOrigin-RevId: 336186795
2020-10-07Add staticcheck and staticstyle analyzers.Adin Scannell
This change also adds support to go_stateify for detecting an appropriate receiver name, avoiding a large number of false positives. PiperOrigin-RevId: 335994587
2020-10-06Implement membarrier(2) commands other than *_SYNC_CORE.Jamie Liu
Updates #267 PiperOrigin-RevId: 335713923
2020-09-18Use a tmpfs file for shared anonymous and /dev/zero mmap on VFS2.Jamie Liu
This is more consistent with Linux (see comment on MM.NewSharedAnonMappable()). We don't do the same thing on VFS1 for reasons documented by the updated comment. PiperOrigin-RevId: 332514849
2020-08-25Use new reference count utility throughout gvisor.Dean Deng
This uses the refs_vfs2 template in vfs2 as well as objects common to vfs1 and vfs2. Note that vfs1-only refcounts are not replaced, since vfs1 will be deleted soon anyway. The following structs now use the new tool, with leak check enabled: devpts:rootInode fuse:inode kernfs:Dentry kernfs:dir kernfs:readonlyDir kernfs:StaticDirectory proc:fdDirInode proc:fdInfoDirInode proc:subtasksInode proc:taskInode proc:tasksInode vfs:FileDescription vfs:MountNamespace vfs:Filesystem sys:dir kernel:FSContext kernel:ProcessGroup kernel:Session shm:Shm mm:aioMappable mm:SpecialMappable transport:queue And the following use the template, but because they currently are not leak checked, a TODO is left instead of enabling leak check in this patch: kernel:FDTable tun:tunEndpoint Updates #1486. PiperOrigin-RevId: 328460377
2020-08-20Consistent 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
2020-08-03Add callbacks to support lazy loading/restoring thread statesAndrei Vagin
PiperOrigin-RevId: 324748508
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
2020-05-20Implement gap tracking in the segment set.Reapor-Yurnero
This change was derived from a change by: Reapor-Yurnero <reapor.yurnero@gmail.com> And has been modified by: Adin Scannell <ascannell@google.com> (The original change author is preserved for the commit.) This change implements gap tracking in the segment set by adding additional information in each node, and using that information to speed up gap finding from a linear scan to a O(log(n)) walk of the tree. This gap tracking is optional, and will default to off except for segment instances that set gapTracking equal to 1 in their const lists. PiperOrigin-RevId: 312621607
2020-04-23Enable automated marshalling for mempolicy syscalls.Rahat Mahmood
PiperOrigin-RevId: 308170679
2020-04-21Misc VFS2 fixesFabricio Voznika
- 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
2020-04-17Merge pull request #1978 from lubinszARM:pr_signal_mmgVisor bot
PiperOrigin-RevId: 307078788
2020-04-09Remove TODOs from Async IOFabricio Voznika
Block and drain requests in io_destroy(2). Note the reason to create read-only mapping. PiperOrigin-RevId: 305786312
2020-04-08Don't call platform.AddressSpace.MapFile with no permissions.Jamie Liu
PiperOrigin-RevId: 305598136
2020-03-27add arch-specific feature into mmBin Lu
Signed-off-by: Bin Lu <bin.lu@arm.com>
2020-02-25Add option to skip stuck tasks waiting for address spaceFabricio Voznika
PiperOrigin-RevId: 297192390
2020-02-18atomicbitops package cleanupsgVisor bot
- Redocument memory ordering from "no ordering" to "acquire-release". (No functional change: both LOCK WHATEVER on x86, and LDAXR/STLXR loops on ARM64, already have this property.) - Remove IncUnlessZeroInt32 and DecUnlessOneInt32, which were only faster than the equivalent loops using sync/atomic before the Go compiler inlined non-unsafe.Pointer atomics many releases ago. PiperOrigin-RevId: 295811743
2020-02-14Plumb VFS2 inside the SentrygVisor bot
- 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
2020-01-31Internal change.gVisor bot
PiperOrigin-RevId: 292587459
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
2020-01-27Standardize on tools directory.Adin Scannell
PiperOrigin-RevId: 291745021
2020-01-21Rename DowngradableRWMutex to RWmutex.Ian Gudger
Also renames TMutex to Mutex. These custom mutexes aren't any worse than the standard library versions (same code), so having both seems redundant. PiperOrigin-RevId: 290873587
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
2020-01-03Remove FIXME comments to close old bug.Zach Koopmans
PiperOrigin-RevId: 288075400
2019-11-21Import and structure cleanup.Adin Scannell
PiperOrigin-RevId: 281795269
2019-10-16Reorder BUILD license and load functions in gvisor.Kevin Krakauer
PiperOrigin-RevId: 275139066
2019-09-12Remove go_test from go_stateify and go_marshalMichael Pratt
They are no-ops, so the standard rule works fine. PiperOrigin-RevId: 268776264
2019-08-16procfs: Migrate seqfile implementations.Ayush Ranjan
Migrates all (except 3) seqfile implementations to the vfs.DynamicBytesSource interface. There should not be any change in functionality due to this migration itself. Please note that the following seqfile implementations have not been migrated: - /proc/filesystems in proc/filesystems.go - /proc/[pid]/mountinfo in proc/mounts.go - /proc/[pid]/mounts in proc/mounts.go This is because these depend on pending changes in /pkg/senty/vfs. PiperOrigin-RevId: 263880719
2019-06-28Add finalizer on AtomicRefCount to check for leaks.Ian Gudger
PiperOrigin-RevId: 255711454
2019-06-27Fix various spelling issues in the documentationMichael Pratt
Addresses obvious typos, in the documentation only. COPYBARA_INTEGRATE_REVIEW=https://github.com/google/gvisor/pull/443 from Pixep:fix/documentation-spelling 4d0688164eafaf0b3010e5f4824b35d1e7176d65 PiperOrigin-RevId: 255477779
2019-06-20Implement madvise(MADV_DONTFORK)Neel Natu
PiperOrigin-RevId: 254253777
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
2019-06-06"Implement" mbind(2).Jamie Liu
We still only advertise a single NUMA node, and ignore mempolicy accordingly, but mbind() at least now succeeds and has effects reflected by get_mempolicy(). Also fix handling of nodemasks: round sizes to unsigned long (as documented and done by Linux), and zero trailing bits when copying them out. PiperOrigin-RevId: 251950859
2019-06-05Implement dumpability tracking and checksMichael Pratt
We don't actually support core dumps, but some applications want to get/set dumpability, which still has an effect in procfs. Lack of support for set-uid binaries or fs creds simplifies things a bit. As-is, processes started via CreateProcess (i.e., init and sentryctl exec) have normal dumpability. I'm a bit torn on whether sentryctl exec tasks should be dumpable, but at least since they have no parent normal UID/GID checks should protect them. PiperOrigin-RevId: 251712714
2019-06-03gvisor: validate a new map region in the mremap syscallAndrei Vagin
Right now, mremap allows to remap a memory region over MaxUserAddress, this means that we can change the stub region. PiperOrigin-RevId: 251266886
2019-05-30Add VmData field to /proc/{pid}/statuschris.zn
VmData is the size of private data segments. It has the same meaning as in Linux. Change-Id: Iebf1ae85940a810524a6cde9c2e767d4233ddb2a PiperOrigin-RevId: 250593739
2019-05-06Ensure all uses of MM.brk occur under MM.mappingMu in MM.Brk().Jamie Liu
PiperOrigin-RevId: 246921386 Change-Id: I71d8908858f45a9a33a0483470d0240eaf0fd012
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
2019-04-10Internal changeMichael Pratt
PiperOrigin-RevId: 242978508 Change-Id: I0ea59ac5ba1dd499e87c53f2e24709371048679b
2019-04-10Allow threads with CAP_SYS_RESOURCE to raise hard rlimits.Kevin Krakauer
PiperOrigin-RevId: 242919489 Change-Id: Ie3267b3bcd8a54b54bc16a6556369a19e843376f
2019-04-01Don't expand COW-break on executable VMAs.Jamie Liu
PiperOrigin-RevId: 241403847 Change-Id: I4631ca05734142da6e80cdfa1a1d63ed68aa05cc
2019-03-29Drop reference on shared anon mappableMichael Pratt
We call NewSharedAnonMappable simply to use it for Mappable/MappingIdentity for shared anon mmap. From MMapOpts.MappingIdentity: "If MMapOpts is used to successfully create a memory mapping, a reference is taken on MappingIdentity." mm.createVMALocked (below) takes this additional reference, so we don't need the reference returned by NewSharedAnonMappable. Holding it leaks the mappable. PiperOrigin-RevId: 241038108 Change-Id: I78ee3af78e0cc7aac4063b274b30d0e41eb5677d
2019-03-25Call memmap.Mappable.Translate with more conservative usermem.AccessType.Jamie Liu
MM.insertPMAsLocked() passes vma.maxPerms to memmap.Mappable.Translate (although it unsets AccessType.Write if the vma is private). This somewhat simplifies handling of pmas, since it means only COW-break needs to replace existing pmas. However, it also means that a MAP_SHARED mapping of a file opened O_RDWR dirties the file, regardless of the mapping's permissions and whether or not the mapping is ever actually written to with I/O that ignores permissions (e.g. ptrace(PTRACE_POKEDATA)). To fix this: - Change the pma-getting path to request only the permissions that are required for the calling access. - Change memmap.Mappable.Translate to take requested permissions, and return allowed permissions. This preserves the existing behavior in the common cases where the memmap.Mappable isn't fsutil.CachingInodeOperations and doesn't care if the translated platform.File pages are written to. - Change the MM.getPMAsLocked path to support permission upgrading of pmas outside of copy-on-write. PiperOrigin-RevId: 240196979 Change-Id: Ie0147c62c1fbc409467a6fa16269a413f3d7d571
2019-03-14Decouple filemem from platform and move it to pgalloc.MemoryFile.Jamie Liu
This is in preparation for improved page cache reclaim, which requires greater integration between the page cache and page allocator. PiperOrigin-RevId: 238444706 Change-Id: Id24141b3678d96c7d7dc24baddd9be555bffafe4
2019-03-12Clarify the platform.File interface.Jamie Liu
- Redefine some memmap.Mappable, platform.File, and platform.Memory semantics in terms of File reference counts (no functional change). - Make AddressSpace.MapFile take a platform.File instead of a raw FD, and replace platform.File.MapInto with platform.File.FD. This allows kvm.AddressSpace.MapFile to always use platform.File.MapInternal instead of maintaining its own (redundant) cache of file mappings in the sentry address space. PiperOrigin-RevId: 238044504 Change-Id: Ib73a11e4275c0da0126d0194aa6c6017a9cef64f
2019-03-05Priority-inheritance futex implementationFabricio Voznika
It is Implemented without the priority inheritance part given that gVisor defers scheduling decisions to Go runtime and doesn't have control over it. PiperOrigin-RevId: 236989545 Change-Id: I714c8ca0798743ecf3167b14ffeb5cd834302560
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