Linux controls socket send/receive buffers using a few sysctl variables
- net.core.rmem_default
- net.core.rmem_max
- net.core.wmem_max
- net.core.wmem_default
- net.ipv4.tcp_rmem
- net.ipv4.tcp_wmem
The first 4 control the default socket buffer sizes for all sockets
raw/packet/tcp/udp and also the maximum permitted socket buffer that can be
specified in setsockopt(SOL_SOCKET, SO_(RCV|SND)BUF,...).
The last two control the TCP auto-tuning limits and override the default
specified in rmem_default/wmem_default as well as the max limits.
Netstack today only implements tcp_rmem/tcp_wmem and incorrectly uses it
to limit the maximum size in setsockopt() as well as uses it for raw/udp
sockets.
This changelist introduces the other 4 and updates the udp/raw sockets to use
the newly introduced variables. The values for min/max match the current
tcp_rmem/wmem values and the default value buffers for UDP/RAW sockets is
updated to match the linux value of 212KiB up from the really low current value
of 32 KiB.
Updates #3043Fixes#3043
PiperOrigin-RevId: 318089805
Metadata was useful for debugging and safety, but enough tests exist that we
should see failures when (de)serialization is broken. It made stack
initialization more cumbersome and it's also getting in the way of ip6tables.
PiperOrigin-RevId: 317210653
Major differences from existing overlay filesystems:
- Linux allows lower layers in an overlay to require revalidation, but not the
upper layer. VFS1 allows the upper layer in an overlay to require
revalidation, but not the lower layer. VFS2 does not allow any layers to
require revalidation. (Now that vfs.MkdirOptions.ForSyntheticMountpoint
exists, no uses of overlay in VFS1 are believed to require upper layer
revalidation; in particular, the requirement that the upper layer support the
creation of "trusted." extended attributes for whiteouts effectively required
the upper filesystem to be tmpfs in most cases.)
- Like VFS1, but unlike Linux, VFS2 overlay does not attempt to make mutations
of the upper layer atomic using a working directory and features like
RENAME_WHITEOUT. (This may change in the future, since not having a working
directory makes error recovery for some operations, e.g. rmdir, particularly
painful.)
- Like Linux, but unlike VFS1, VFS2 represents whiteouts using character
devices with rdev == 0; the equivalent of the whiteout attribute on
directories is xattr trusted.overlay.opaque = "y"; and there is no equivalent
to the whiteout attribute on non-directories since non-directories are never
merged with lower layers.
- Device and inode numbers work as follows:
- In Linux, modulo the xino feature and a special case for when all layers
are the same filesystem:
- Directories use the overlay filesystem's device number and an
ephemeral inode number assigned by the overlay.
- Non-directories that have been copied up use the device and inode
number assigned by the upper filesystem.
- Non-directories that have not been copied up use a per-(overlay,
layer)-pair device number and the inode number assigned by the lower
filesystem.
- In VFS1, device and inode numbers always come from the lower layer unless
"whited out"; this has the adverse effect of requiring interaction with
the lower filesystem even for non-directory files that exist on the upper
layer.
- In VFS2, device and inode numbers are assigned as in Linux, except that
xino and the samefs special case are not supported.
- Like Linux, but unlike VFS1, VFS2 does not attempt to maintain memory mapping
coherence across copy-up. (This may have to change in the future, as users
may be dependent on this property.)
- Like Linux, but unlike VFS1, VFS2 uses the overlayfs mounter's credentials
when interacting with the overlay's layers, rather than the caller's.
- Like Linux, but unlike VFS1, VFS2 permits multiple lower layers in an
overlay.
- Like Linux, but unlike VFS1, VFS2's overlay filesystem is
application-mountable.
Updates #1199
PiperOrigin-RevId: 316019067
Run vs. exec, VFS1 vs. VFS2 were executable lookup were
slightly different from each other. Combine them all
into the same logic.
PiperOrigin-RevId: 315426443
This is mostly syscall plumbing, VFS2 already implements the internals of
mounts. In addition to the syscall defintions, the following mount-related
mechanisms are updated:
- Implement MS_NOATIME for VFS2, but only for tmpfs and goferfs. The other VFS2
filesystems don't implement node-level timestamps yet.
- Implement the 'mode', 'uid' and 'gid' mount options for VFS2's tmpfs.
- Plumb mount namespace ownership, which is necessary for checking appropriate
capabilities during mount(2).
Updates #1035
PiperOrigin-RevId: 315035352
IPTables.connections contains a sync.RWMutex. Copying it will trigger copylocks
analysis. Tested by manually enabling nogo tests.
sync.RWMutex is added to IPTables for the additional race condition discovered.
PiperOrigin-RevId: 314817019
- Add /tmp handling
- Apply mount options
- Enable more container_test tests
- Forward signals to child process when test respaws process
to run as root inside namespace.
Updates #1487
PiperOrigin-RevId: 314263281
Using tee instead of read to detect when a O_RDONLY|O_NONBLOCK pipe FD has a
writer circumvents the problem of what to do with the byte read from the pipe,
avoiding much of the complexity of the fdpipe package.
PiperOrigin-RevId: 314216146
Linux 4.18 and later make reads and writes coherent between pre-copy-up and
post-copy-up FDs representing the same file on an overlay filesystem. However,
memory mappings remain incoherent:
- Documentation/filesystems/overlayfs.rst, "Non-standard behavior": "If a file
residing on a lower layer is opened for read-only and then memory mapped with
MAP_SHARED, then subsequent changes to the file are not reflected in the
memory mapping."
- fs/overlay/file.c:ovl_mmap() passes through to the underlying FD without any
management of coherence in the overlay.
- Experimentally on Linux 5.2:
```
$ cat mmap_cat_page.c
#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>
int main(int argc, char **argv) {
if (argc < 2) {
errx(1, "syntax: %s [FILE]", argv[0]);
}
const int fd = open(argv[1], O_RDONLY);
if (fd < 0) {
err(1, "open(%s)", argv[1]);
}
const size_t page_size = sysconf(_SC_PAGE_SIZE);
void* page = mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0);
if (page == MAP_FAILED) {
err(1, "mmap");
}
for (;;) {
write(1, page, strnlen(page, page_size));
if (getc(stdin) == EOF) {
break;
}
}
return 0;
}
$ gcc -O2 -o mmap_cat_page mmap_cat_page.c
$ mkdir lowerdir upperdir workdir overlaydir
$ echo old > lowerdir/file
$ sudo mount -t overlay -o "lowerdir=lowerdir,upperdir=upperdir,workdir=workdir" none overlaydir
$ ./mmap_cat_page overlaydir/file
old
^Z
[1]+ Stopped ./mmap_cat_page overlaydir/file
$ echo new > overlaydir/file
$ cat overlaydir/file
new
$ fg
./mmap_cat_page overlaydir/file
old
```
Therefore, while the VFS1 gofer client's behavior of reopening read FDs is only
necessary pre-4.18, replacing existing memory mappings (in both sentry and
application address spaces) with mappings of the new FD is required regardless
of kernel version, and this latter behavior is common to both VFS1 and VFS2.
Re-document accordingly, and change the runsc flag to enabled by default.
New test:
- Before this CL: https://source.cloud.google.com/results/invocations/5b222d2c-e918-4bae-afc4-407f5bac509b
- After this CL: https://source.cloud.google.com/results/invocations/f28c747e-d89c-4d8c-a461-602b33e71aab
PiperOrigin-RevId: 311361267
Some code paths needed these syscalls anyways, so they should be included in
the filters. Given that we depend on these syscalls in some cases, there's no
real reason to avoid them any more.
PiperOrigin-RevId: 310829126
Synthetic sockets do not have the race condition issue in VFS2, and we will
get rid of privateunixsocket as well.
Fixes#1200.
PiperOrigin-RevId: 310386474
We can register any number of tables with any number of architectures, and
need not limit the definitions to the architecture in question. This allows
runsc to generate documentation for all architectures simultaneously.
Similarly, this simplifies the VFSv2 patching process.
PiperOrigin-RevId: 310224827
This change includes:
- Modifications to loader_test.go to get TestCreateMountNamespace to
pass with VFS2.
- Changes necessary to get TestHelloWorld in image tests to pass with
VFS2. This means runsc can run the hello-world container with docker
on VSF2.
Note: Containers that use sockets will not run with these changes.
See "//test/image/...". Any tests here with sockets currently fail
(which is all of them but HelloWorld).
PiperOrigin-RevId: 308363072
This is needed to set up host fds passed through a Unix socket. Note that
the host package depends on kernel, so we cannot set up the hostfs mount
directly in Kernel.Init as we do for sockfs and pipefs.
Also, adjust sockfs to make its setup look more like hostfs's and pipefs's.
PiperOrigin-RevId: 308274053
This change adds a layer of abstraction around the internal Docker APIs,
and eliminates all direct dependencies on Dockerfiles in the infrastructure.
A subsequent change will automated the generation of local images (with
efficient caching). Note that this change drops the use of bazel container
rules, as that experiment does not seem to be viable.
PiperOrigin-RevId: 308095430
Included:
- loader_test.go RunTest and TestStartSignal VFS2
- container_test.go TestAppExitStatus on VFS2
- experimental flag added to runsc to turn on VFS2
Note: shared mounts are not yet supported.
PiperOrigin-RevId: 307070753
Suppose I start a runsc container using kvm platform like this:
$ sudo runsc --debug=true --debug-log=1.txt --platform=kvm run rootbash
The donating FD and the corresponding cmdline for runsc-sandbox is:
D0313 17:50:12.608203 44389 x:0] Donating FD 3: "1.txt"
D0313 17:50:12.608214 44389 x:0] Donating FD 4: "control_server_socket"
D0313 17:50:12.608224 44389 x:0] Donating FD 5: "|0"
D0313 17:50:12.608229 44389 x:0] Donating FD 6: "/home/ziqian.lzq/bundle/bash/runsc/config.json"
D0313 17:50:12.608234 44389 x:0] Donating FD 7: "|1"
D0313 17:50:12.608238 44389 x:0] Donating FD 8: "sandbox IO FD"
D0313 17:50:12.608242 44389 x:0] Donating FD 9: "/dev/kvm"
D0313 17:50:12.608246 44389 x:0] Donating FD 10: "/dev/stdin"
D0313 17:50:12.608249 44389 x:0] Donating FD 11: "/dev/stdout"
D0313 17:50:12.608253 44389 x:0] Donating FD 12: "/dev/stderr"
D0313 17:50:12.608257 44389 x:0] Starting sandbox: /proc/self/exe
[runsc-sandbox --root=/run/containerd/runsc/default --debug=true --log=
--max-threads=256 --reclaim-period=5 --log-format=text --debug-log=1.txt
--debug-log-format=text --file-access=exclusive --overlay=false
--fsgofer-host-uds=false --network=sandbox --log-packets=false
--platform=kvm --strace=false --strace-syscalls=--strace-log-size=1024
--watchdog-action=Panic --panic-signal=-1 --profile=false --net-raw=true
--num-network-channels=1 --rootless=false --alsologtostderr=false
--ref-leak-mode=disabled --gso=true --software-gso=true
--overlayfs-stale-read=false --shared-volume= --debug-log-fd=3
--panic-signal=15 boot --bundle=/home/ziqian.lzq/bundle/bash/runsc
--controller-fd=4 --mounts-fd=5 --spec-fd=6 --start-sync-fd=7 --io-fds=8
--device-fd=9 --stdio-fds=10 --stdio-fds=11 --stdio-fds=12 --pidns=true
--setup-root --cpu-num 32 --total-memory 4294967296 rootbash]
Note stdioFDs starts from 10 with kvm platform and stderr's FD is 12.
If I restore a container from the checkpoint image which is derived
by checkpointing the above rootbash container, but either omit the
platform switch or specify to use ptrace platform explicitely:
$ sudo runsc --debug=true --debug-log=1.txt restore --image-path=some_path restored_rootbash
the donating FD and corresponding cmdline for runsc-sandbox is:
D0313 17:50:15.258632 44452 x:0] Donating FD 3: "1.txt"
D0313 17:50:15.258640 44452 x:0] Donating FD 4: "control_server_socket"
D0313 17:50:15.258645 44452 x:0] Donating FD 5: "|0"
D0313 17:50:15.258648 44452 x:0] Donating FD 6: "/home/ziqian.lzq/bundle/bash/runsc/config.json"
D0313 17:50:15.258653 44452 x:0] Donating FD 7: "|1"
D0313 17:50:15.258657 44452 x:0] Donating FD 8: "sandbox IO FD"
D0313 17:50:15.258661 44452 x:0] Donating FD 9: "/dev/stdin"
D0313 17:50:15.258675 44452 x:0] Donating FD 10: "/dev/stdout"
D0313 17:50:15.258680 44452 x:0] Donating FD 11: "/dev/stderr"
D0313 17:50:15.258684 44452 x:0] Starting sandbox: /proc/self/exe
[runsc-sandbox --root=/run/containerd/runsc/default --debug=true --log=
--max-threads=256 --reclaim-period=5 --log-format=text --debug-log=1.txt
--debug-log-format=text --file-access=exclusive --overlay=false
--fsgofer-host-uds=false --network=sandbox --log-packets=false
--platform=ptrace --strace=false --strace-syscalls=
--strace-log-size=1024 --watchdog-action=Panic --panic-signal=-1
--profile=false --net-raw=true --num-network-channels=1 --rootless=false
--alsologtostderr=false --ref-leak-mode=disabled --gso=true
--software-gso=true --overlayfs-stale-read=false --shared-volume=
--debug-log-fd=3 --panic-signal=15 boot
--bundle=/home/ziqian.lzq/bundle/bash/runsc --controller-fd=4
--mounts-fd=5 --spec-fd=6 --start-sync-fd=7 --io-fds=8 --stdio-fds=9
--stdio-fds=10 --stdio-fds=11 --setup-root --cpu-num 32 --total-memory
4294967296 restored_rootbash]
Note this time, stdioFDs starts from 9 and stderr's FD is 11(so the
saved host.descritor.origFD which is 12 for stderr is no longer valid).
For the three host FD based files, The s.Dev and s.Ino derived from
fstat(fd) shall all be the same and since the two fields are used
as device.MultiDeviceKey, the host.inodeFileState.sattr.InodeId which is
the value of MultiDevice.Map(MultiDeviceKey), shall also all be the same.
Note that for MultiDevice m, m.cache records the mapping of key to value
and m.rcache records the mapping of value to key. If same value doesn't
map to the same key, it will panic on restore.
Now that stderr's origFD 12 is no longer valid(it happens to be
/memfd:runsc-memory in my test on restore), the s.Dev and s.Ino derived
from fstat(fd=12) in host.inodeFileState.afterLoad() will neither be
correct. But its InodeID is still the same as saved, MultiDevice.Load()
will complain about the same value(InodeID) being mapped to different
keys (different from stdin and stdout's) and panic with: "MultiDevice's
caches are inconsistent".
Solve this problem by making sure stdioFDs for root container's init
task are always the same on initial start and on restore time, no matter
what cmdline user has used: debug log specified or not, platform changed
or not etc. shall not affect the ability to restore.
Fixes#1844.
Using the host-defined file owner matches VFS1. It is more correct to use the
host-defined mode, since the cached value may become out of date. However,
kernfs.Inode.Mode() does not return an error--other filesystems on kernfs are
in-memory so retrieving mode should not fail. Therefore, if the host syscall
fails, we rely on a cached value instead.
Updates #1672.
PiperOrigin-RevId: 303220864
utimensat is used by hostfs for setting timestamps on imported fds. Previously,
this would crash the sandbox since utimensat was not allowed.
Correct the VFS2 version of hostfs to match the call in VFS1.
PiperOrigin-RevId: 301970121
- When setting up the virtual filesystem, mount a host.filesystem to contain
all files that need to be imported.
- Make read/preadv syscalls to the host in cases where preadv2 may not be
supported yet (likewise for writing).
- Make save/restore functions in kernel/kernel.go return early if vfs2 is
enabled.
PiperOrigin-RevId: 300922353
Ayush Ranjan
Ridwan Sharif
Nicolas Lacasse
Bhasker Hariharan
Kevin Krakauer
gVisor bot
Ian Lewis
Jamie Liu
Fabricio Voznika
Rahat Mahmood
Ting-Yu Wang
Dean Deng
Adin Scannell
moricho
Zach Koopmans
Aaron Lu