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Split usermem package to help remove syserror dependency in go_marshal.
New hostarch package contains code not dependent on syserror.
PiperOrigin-RevId: 365651233
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On Linux these are meant to be equivalent to POLLIN/POLLOUT. Rather
than hack these on in sys_poll etc it felt cleaner to just cleanup
the call sites to notify for both events. This is what linux does
as well.
Fixes #5544
PiperOrigin-RevId: 364859977
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By default, fusefs defers node permission checks to the server. The
default_permissions mount option enables the usual unix permission
checks based on the node owner and mode bits. Previously fusefs was
incorrectly checking permissions unconditionally.
Additionally, fusefs should restrict filesystem access to processes
started by the mount owner to prevent the fuse daemon from gaining
priviledge over other processes. The allow_other mount option
overrides this behaviour. Previously fusefs was incorrectly skipping
this check.
Updates #3229
PiperOrigin-RevId: 362419092
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PiperOrigin-RevId: 362406813
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The syscall package has been deprecated in favor of golang.org/x/sys.
Note that syscall is still used in the following places:
- pkg/sentry/socket/hostinet/stack.go: some netlink related functionalities
are not yet available in golang.org/x/sys.
- syscall.Stat_t is still used in some places because os.FileInfo.Sys() still
returns it and not unix.Stat_t.
Updates #214
PiperOrigin-RevId: 360701387
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Reported-by: syzbot+814105309d2ae8651084@syzkaller.appspotmail.com
PiperOrigin-RevId: 350159452
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PiperOrigin-RevId: 347047550
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Don't propagate arbitrary golang errors up from fusefs because errors
that don't map to an errno result in a sentry panic.
Reported-by: syzbot+697cb635346e456fddfc@syzkaller.appspotmail.com
PiperOrigin-RevId: 346220306
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PiperOrigin-RevId: 342992936
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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
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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
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PiperOrigin-RevId: 340536306
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Updates #1486.
PiperOrigin-RevId: 339581879
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Added the following fields in kernfs.InodeAttr:
- blockSize
- atime
- mtime
- ctime
Also resolved all TODOs for #1193.
Fixes #1193
PiperOrigin-RevId: 338714527
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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
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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
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This change aims to fix the memory leak issue reported inĀ #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
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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
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Updates #1663
PiperOrigin-RevId: 333539293
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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
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There were some instances where we were not enabling leak checking.
PiperOrigin-RevId: 333418571
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Update signatures for:
- walkExistingLocked
- checkDeleteLocked
- Inode.Open
Updates #1193
PiperOrigin-RevId: 333163381
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Updates #1193.
PiperOrigin-RevId: 332939026
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PiperOrigin-RevId: 332486111
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This fixes a use-after-free in fuse.DeviceFD.Release.
PiperOrigin-RevId: 332394146
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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>
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fix #3956
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fix #3963
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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
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Fixes #3696
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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.
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This commit fixes the potential unexpected errors
of original handling of FUSE_RELEASE responses while
keep the same behavior (ignoring any reply).
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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.
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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.
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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
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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
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This commit adds basic write(2) support for FUSE.
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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
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This change removes the unnecessary loop and avoids
the recursive call. It also fixes minor bugs in this
function.
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This commit removes unused marshalling functions in linux abi package
and moves self-defined FUSEInitRes wrapper to fuse package.
Updates #3707
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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
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kernfs uses inode.Getlink to resolve symlink when look up paths.
Updates #3452
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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
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