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Kernfs provides an internal mechanism to defer calls to `DecRef()` because
on the last reference `Filesystem.mu` must be held and most places that
need to call `DecRef()` are inside the lock. The same can be true for
filesystems that extend kernfs. procfs needs to look up files and `DecRef()`
them inside the `kernfs.Filesystem.mu`. If the files happen to be procfs
files, it can deadlock trying to decrement if it's the last reference.
This change extends the mechanism to external callers to defer DecRefs
to `vfs.FileDescription` and `vfs.VirtualDentries`.
PiperOrigin-RevId: 384361647
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Set stdio ownership based on the container's user to ensure the
user can open/read/write to/from stdios.
1. stdios in the host are changed to have the owner be the same
uid/gid of the process running the sandbox. This ensures that the
sandbox has full control over it.
2. stdios owner owner inside the sandbox is changed to match the
container's user to give access inside the container and make it
behave the same as runc.
Fixes #6180
PiperOrigin-RevId: 384347009
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Update the following from syserror to the linuxerr equivalent:
EEXIST
EFAULT
ENOTDIR
ENOTTY
EOPNOTSUPP
ERANGE
ESRCH
PiperOrigin-RevId: 384329869
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PiperOrigin-RevId: 383684320
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This change makes the checklocks analyzer considerable more powerful, adding:
* The ability to traverse complex structures, e.g. to have multiple nested
fields as part of the annotation.
* The ability to resolve simple anonymous functions and closures, and perform
lock analysis across these invocations. This does not apply to closures that
are passed elsewhere, since it is not possible to know the context in which
they might be invoked.
* The ability to annotate return values in addition to receivers and other
parameters, with the same complex structures noted above.
* Ignoring locking semantics for "fresh" objects, i.e. objects that are
allocated in the local frame (typically a new-style function).
* Sanity checking of locking state across block transitions and returns, to
ensure that no unexpected locks are held.
Note that initially, most of these findings are excluded by a comprehensive
nogo.yaml. The findings that are included are fundamental lock violations.
The changes here should be relatively low risk, minor refactorings to either
include necessary annotations to simplify the code structure (in general
removing closures in favor of methods) so that the analyzer can be easily
track the lock state.
This change additional includes two changes to nogo itself:
* Sanity checking of all types to ensure that the binary and ast-derived
types have a consistent objectpath, to prevent the bug above from occurring
silently (and causing much confusion). This also requires a trick in
order to ensure that serialized facts are consumable downstream. This can
be removed with https://go-review.googlesource.com/c/tools/+/331789 merged.
* A minor refactoring to isolation the objdump settings in its own package.
This was originally used to implement the sanity check above, but this
information is now being passed another way. The minor refactor is preserved
however, since it cleans up the code slightly and is minimal risk.
PiperOrigin-RevId: 382613300
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Update/remove most syserror errors to linuxerr equivalents. For list
of removed errors, see //pkg/syserror/syserror.go.
PiperOrigin-RevId: 382574582
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Update all instances of the above errors to the faster linuxerr implementation.
With the temporary linuxerr.Equals(), no logical changes are made.
PiperOrigin-RevId: 382306655
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The unordered map may generate different hash due to its order. The
children map needs to be sorted each time before hashing to avoid false
verification failure due to the map.
Store the sorted children map in verity dentry to avoid sorting it each
time verification happens.
Also serialize the whole VerityDescriptor struct to hash now that the
map is removed from it.
PiperOrigin-RevId: 382201560
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Remove three syserror entries duplicated in linuxerr. Because of the
linuxerr.Equals method, this is a mere change of return values from
syserror to linuxerr definitions.
Done with only these three errnos as CLs removing all grow to a significantly
large size.
PiperOrigin-RevId: 382173835
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PiperOrigin-RevId: 381982257
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PiperOrigin-RevId: 381375705
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Add Equals method to compare syserror and unix.Errno errors to linuxerr errors.
This will facilitate removal of syserror definitions in a followup, and
finding needed conversions from unix.Errno to linuxerr.
PiperOrigin-RevId: 380909667
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...and pass it explicitly.
This reverts commit b63e61828d0652ad1769db342c17a3529d2d24ed.
PiperOrigin-RevId: 380039167
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- Allow the gofer client to use most xattr namespaces. As documented by the
updated comment, this is consistent with e.g. Linux's FUSE client, and allows
gofers to provide extended attributes from FUSE filesystems.
- Make tmpfs' listxattr omit xattrs in the "trusted" namespace for
non-privileged users.
PiperOrigin-RevId: 378778854
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The control files enumerating tasks and threads residing in cgroupfs
incorrectly locks cgroupfs.filesystem.tasksMu before
kernel.TaskSet.mu.
The contents of these control files are inherently racy anyways, so
use a snapshot of the tasks in the cgroup and drop tasksMu before
resolving pids/tids (which acquires TaskSet.mu).
PiperOrigin-RevId: 378767060
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Set it to int32 max because gVisor doesn't have a limit.
Fixes #2337
PiperOrigin-RevId: 378722230
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PiperOrigin-RevId: 377966969
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Avoids a race condition at kernel initialization.
Updates #6057.
PiperOrigin-RevId: 377357723
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PiperOrigin-RevId: 376001603
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PiperOrigin-RevId: 375843579
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Remove useless conversions. Avoid unhandled errors.
PiperOrigin-RevId: 375834275
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PiperOrigin-RevId: 375780659
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This metric is replaced by /cloud/gvisor/sandbox/sentry/suspicious_operations
metric with field value opened_write_execute_file.
PiperOrigin-RevId: 374509823
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The new metric contains fields and will replace the below existing metric:
- opened_write_execute_file
PiperOrigin-RevId: 373884604
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O_PATH is now implemented in vfs2.
Fixes #2782.
PiperOrigin-RevId: 373861410
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https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt:
/proc/sys/net/ipv4/* Variables:
ip_forward - BOOLEAN
0 - disabled (default)
not 0 - enabled
Forward Packets between interfaces.
This variable is special, its change resets all configuration
parameters to their default state (RFC1122 for hosts, RFC1812
for routers)
/proc/sys/net/ipv4/ip_forward only does work when its value is changed
and always returns the last written value. The last written value may
not reflect the current state of the netstack (e.g. when `ip_forward`
was written a value of "1" then disable forwarding on an interface)
so there is no need for sentry to probe netstack to get the current
forwarding state of interfaces.
```
~$ cat /proc/sys/net/ipv4/ip_forward
0
~$ sudo bash -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
~$ cat /proc/sys/net/ipv4/ip_forward
1
~$ sudo sysctl -a | grep ipv4 | grep forward
net.ipv4.conf.all.forwarding = 1
net.ipv4.conf.default.forwarding = 1
net.ipv4.conf.eno1.forwarding = 1
net.ipv4.conf.lo.forwarding = 1
net.ipv4.conf.wlp1s0.forwarding = 1
net.ipv4.ip_forward = 1
net.ipv4.ip_forward_update_priority = 1
net.ipv4.ip_forward_use_pmtu = 0
~$ sudo sysctl -w net.ipv4.conf.wlp1s0.forwarding=0
net.ipv4.conf.wlp1s0.forwarding = 0
~$ sudo sysctl -a | grep ipv4 | grep forward
net.ipv4.conf.all.forwarding = 1
net.ipv4.conf.default.forwarding = 1
net.ipv4.conf.eno1.forwarding = 1
net.ipv4.conf.lo.forwarding = 1
net.ipv4.conf.wlp1s0.forwarding = 0
net.ipv4.ip_forward = 1
net.ipv4.ip_forward_update_priority = 1
net.ipv4.ip_forward_use_pmtu = 0
~$ cat /proc/sys/net/ipv4/ip_forward
1
~$ sudo bash -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
~$ sudo sysctl -a | grep ipv4 | grep forward
net.ipv4.conf.all.forwarding = 1
net.ipv4.conf.default.forwarding = 1
net.ipv4.conf.eno1.forwarding = 1
net.ipv4.conf.lo.forwarding = 1
net.ipv4.conf.wlp1s0.forwarding = 0
net.ipv4.ip_forward = 1
net.ipv4.ip_forward_update_priority = 1
net.ipv4.ip_forward_use_pmtu = 0
~$ sudo bash -c "echo 0 > /proc/sys/net/ipv4/ip_forward"
~$ sudo sysctl -a | grep ipv4 | grep forward
sysctl: unable to open directory "/proc/sys/fs/binfmt_misc/"
net.ipv4.conf.all.forwarding = 0
net.ipv4.conf.default.forwarding = 0
net.ipv4.conf.eno1.forwarding = 0
net.ipv4.conf.lo.forwarding = 0
net.ipv4.conf.wlp1s0.forwarding = 0
net.ipv4.ip_forward = 0
net.ipv4.ip_forward_update_priority = 1
net.ipv4.ip_forward_use_pmtu = 0
~$ cat /proc/sys/net/ipv4/ip_forward
0
```
In the above example we can see that writing "1" to
/proc/sys/net/ipv4/ip_forward configures the stack to be a router (all
interfaces are configured to enable forwarding). However, if we manually
update an interace (`wlp1s0`) to not forward packets,
/proc/sys/net/ipv4/ip_forward continues to return the last written value
of "1", even though not all interfaces will forward packets.
Also note that writing the same value twice has no effect; work is
performed iff the value changes.
This change also removes the 'unset' state from sentry's ip forwarding
data structures as an 'unset' ip forwarding value is the same as leaving
forwarding disabled as the stack is always brought up with forwarding
initially disabled; disabling forwarding on a newly created stack is a
no-op.
PiperOrigin-RevId: 373853106
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Previously, registration was racy because we were publishing
hierarchies in the registry without fully initializing the underlying
filesystem. This led to concurrent mount(2)s discovering the partially
intialized filesystems and dropping the final refs on them which cause
them to be freed prematurely.
Reported-by: syzbot+13f54e77bdf59f0171f0@syzkaller.appspotmail.com
Reported-by: syzbot+2c7f0a9127ac6a84f17e@syzkaller.appspotmail.com
PiperOrigin-RevId: 373824552
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Fix TODO comments referring to incorrect issue numbers. Also fix the link in
issue reviver comments to include the right url fragment.
PiperOrigin-RevId: 373491821
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This change implements /proc/cmdline with a basic faux command line
"BOOT_IMAGE=/vmlinuz-[version]-gvisor quiet" so apps that may expect
it do not receive errors.
Also tests for the existence of /proc/cmdline as part of the system
call test suite
PiperOrigin-RevId: 372462070
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PiperOrigin-RevId: 372020696
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In order to resolve path names, fsSymlink.Readlink() may need to reenter
kernfs. Change the code so that kernfs.Inode.Readlink() is called without
locks and document the new contract.
PiperOrigin-RevId: 371770222
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When a child is added to a parent (directory) dentry, both child and parent are
queued for checkCachingLocked(). Make sure that the parent is queued first
because the parent gained a ref and so could be removed from the LRU cache hence
making space for the new child. This could prevent an LRU cache eviction.
In practice, this did seem to help. ~800 RPCs were reduced while building
//absl/... (ABSL build benchmark). Evictions hurt in 2 ways - create renameMu
contention and destroy a possibly useful dentry which will have to be re-walked
and re-opened later.
Follow up fix for #5859.
PiperOrigin-RevId: 371509392
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If verification fails for translating mmapped memory, the content should
not be returned. This is not an issue for panic mode, but for error mode
we should return empty content along with the error.
PiperOrigin-RevId: 371393519
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Originally we were making a WalkGetAttrOne RPC to confirm that a file does not
exist on the remote filesystem - when there was no cached information about the
existence of a dentry at that position.
This change avoids making that RPC and speculatively makes the
mkdir/mknod/linkat/symlink RPC. They will fail with EEXIST if a file exists at
that position as we want.
However the error ordering is important. Existence check comes before
writability check. So we make the existence check when the writability check
fails and give it precedence.
This change saves ~76,000 RPCs while building //absl/... (ABSL build benchmark).
That is 10% of all RPCs made while running that workload.
PiperOrigin-RevId: 371225633
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PiperOrigin-RevId: 371198372
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PiperOrigin-RevId: 371015541
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Weirdness metric contains fields to track the number of clock fallback,
partial result and vsyscalls. This metric will avoid the overhead of
having three different metrics (fallbackMetric, partialResultMetric,
vsyscallCount).
PiperOrigin-RevId: 369970218
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PiperOrigin-RevId: 369724358
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PiperOrigin-RevId: 369686285
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The gofer client's LRU cache has a default limit of 1000 dentries. Any attempt
to cache more dentries than that will make the LRU cache evict and destroy the
least recently used dentry. However, the eviction is expensive because it
requires holding fs.renameMu for writing - which in turn creates a lot of
contention. All filesystem operations that involve path traversal require
fs.renameMu for reading atleast.
Therefore, it is in our best interest to keep the cache small and clean.
When a dentry is inserted in the dentry tree, it grabs a ref on its parent for
its entire lifetime. Hence the parent is longer evictable (because refs > 0).
This change additionally calls checkCachingLocked on directories that have been
added to so that they can be removed from the LRU cache if needed.
This change implies that the LRU cache will only contain the leaves from the
filesystem tree which significantly reduces the LRU cache size and consequently
reduces the number of expensive LRU cache evictions.
> Why are opened dentries not removed from LRU cache?
When a file description is open(2)-ed, the file description holds a ref on its
dentry for its entire lifetime. However, calling checkCachingLocked() on opened
dentries actually ends up hurting performance. Applications usually open file
descriptors for a short duration. So upon close(2), the dentry is reinserted
into the cache anyway. So the precautionary work done in removing the opened
dentry from the cache went for waste as it did not really reduce an eviction.
Local benchmarking has shown that this change improves performance by 3-4%.
Across 6 runs, without this change it took 296.127 seconds to build runsc while
with this change it took only 285.136 seconds.
PiperOrigin-RevId: 369510494
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Remote revalidating requires to update file size on every write
on a file opened with O_APPEND. If host FD exists, it can be
used to update the size and skip round trip to the gofer. With
this change, O_APPEND writes with remote revalidating is almost
as fast as exclusive mode:
BM_Append
VFS1 60.7us
VFS2 56.8us
VFS2 exclusive 14.2us
This change 15.8us
Updates #1792
PiperOrigin-RevId: 369486801
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Fixes #2926, #674
PiperOrigin-RevId: 369457123
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Currently the verity action is a global variable, which causes the same
action for all verity mounts, and is overwritten for each new verity
mount. Changed it to a member of verity fs.
PiperOrigin-RevId: 369348522
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While using remote-validation, the vast majority of time spent during
FS operations is re-walking the path to check for modifications and
then closing the file given that in most cases it has not been
modified externally.
This change introduces a new 9P message called MultiGetAttr which bulks
query attributes of several files in one shot. The returned attributes are
then used to update cached dentries before they are walked. File attributes
are updated for files that still exist. Dentries that have been deleted are
removed from the cache. And negative cache entries are removed if a new
file/directory was created externally. Similarly, synthetic dentries are
replaced if a file/directory is created externally.
The bulk update needs to be carefull not to follow symlinks, cross mount
points, because the gofer doesn't know how to resolve symlinks and where
mounts points are located. It also doesn't walk to the parent ("..") to
avoid deadlocks.
Here are the results:
Workload VFS1 VFS2 Change
bazel action 115s 70s 28.8s
Stat/100 11,043us 7,623us 974us
Updates #1638
PiperOrigin-RevId: 369325957
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Runsc build benchmark's mutex profile shows that we are wasting roughly 25-30
seconds waiting for filesystem.renameMu to get unlocked. Earlier
checkCachingLocked required the renameMu to be locked for writing. This is a
filesystem wide lock which puts all other filesystem operations on hold and
hence is really expensive. Something to note is that all path resolution
operations hold renameMu for reading.
With this change, we allow to check for caching without even holding renameMu.
This change introduces more fine grained locks (fs.cacheMu and dentry.cachingMu)
which protect the cache (removing the requirement to hold renameMu for writing
to modify the cache) and synchronize concurrent dentry caching attempts on a per
dentry basis. We still require to hold renameMu for writing while destroying
dentries and evicting from the cache but this still significantly reduces the
write locking critical section.
Local benchmarking showed that this improved runsc build benchmark time by 4-5%.
Across 6 runs, without this change it took 310.9025 seconds to build runsc
while with this change it took 296.127 seconds.
Runsc build benchmark's mutex profile: https://gvisor.dev/profile/gvisor-buildkite/78a3f968-36ca-4944-93f7-77a8792d56b4/28a1d260-790b-4a9e-94da-a4daede08ee3/tmp/profile/ptrace/BenchmarkBuildRunsc/page_cache.clean/filesystem.bindfs/benchmarks/runsc/mutex.pprof/flamegraph
PiperOrigin-RevId: 368958136
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Add a coverage-report flag that will cause the sandbox to generate a coverage
report (with suffix .cov) in the debug log directory upon exiting. For the
report to be generated, runsc must have been built with the following Bazel
flags: `--collect_code_coverage --instrumentation_filter=...`.
With coverage reports, we should be able to aggregate results across all tests
to surface code coverage statistics for the project as a whole.
The report is simply a text file with each line representing a covered block
as `file:start_line.start_col,end_line.end_col`. Note that this is similar to
the format of coverage reports generated with `go test -coverprofile`,
although we omit the count and number of statements, which are not useful for
us.
Some simple ways of getting coverage reports:
bazel test <some_test> --collect_code_coverage \
--instrumentation_filter=//pkg/...
bazel build //runsc --collect_code_coverage \
--instrumentation_filter=//pkg/...
runsc -coverage-report=dir/ <other_flags> do ...
PiperOrigin-RevId: 368952911
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Otherwise ConnectedEndpoint.sndbuf will be restored as 0 and writes
to the socket will fail with EAGAIN.
PiperOrigin-RevId: 368746660
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Thanks ianlewis@ for discovering the bug/fix!
PiperOrigin-RevId: 368740744
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Some FileDescriptions in verity fs were opened but DecRef() were missing
after used. This could result in a ref leak.
PiperOrigin-RevId: 368096759
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If the parent is not enabled in verity stepLocked(), failure to find
the child dentry could just mean an incorrect path.
PiperOrigin-RevId: 367733412
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