CentOS 7 is showing its age and we'd rather skip some tests on it than
find out why they are flaky.
Add internal/testutil package, and move the generalized version of
SkipOnCentOS7 from libcontainer/cgroups/devices to there.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Since systemd v240 (commit 8e8b5d2e6d91180a), one can use
/dev/{char,block}-MAJOR syntax to specify that all MAJOR:*
devices are allowed.
Use it, if available, since it's more straightforward, plus
we can skip somewhat expensive parsing of /proc/devices.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
1. Use strings.TrimPrefix instead of fmt.Sscanf and simplify the code.
2. Add a test case and a benchmark.
The benchmark shows some improvement, compared to the old
implementation:
name old time/op new time/op delta
FindDeviceGroup-4 39.7µs ± 2% 26.8µs ± 2% -32.63% (p=0.008 n=5+5)
name old alloc/op new alloc/op delta
FindDeviceGroup-4 6.08kB ± 0% 4.23kB ± 0% -30.39% (p=0.008 n=5+5)
name old allocs/op new allocs/op delta
FindDeviceGroup-4 117 ± 0% 6 ± 0% -94.87% (p=0.008 n=5+5)
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Commit 343951a22b added a call to os.Stat for the device path
when generating systemd device properties, to avoid systemd warning for
non-existing devices. The idea was, since systemd uses stat(2) to look
up device properties for a given path, it will fail anyway. In addition,
this allowed to suppress a warning like this from systemd:
> Couldn't stat device /dev/char/10:200
NOTE that this was done because:
- systemd could not add the rule anyway;
- runs puts its own set of rules on top of what systemd does.
Apparently, the above change broke some setups, resulting in inability
to use e.g. /dev/null inside a container. My guess is this is because
in cgroup v2 we add a second eBPF program, which is not used if the
first one (added by systemd) returns "access denied".
Next, commit 3b9582895b fixed that by adding a call to os.Stat for
"/sys/"+path (meaning, if "/dev/char/10:200" does not exist, we retry
with "/sys/dev/char/10:200", and if it exists, proceed with adding a
device rule with the original (non-"/sys") path).
How that second fix ever worked was a mystery, because the path we gave
to systemd still doesn't exist.
Well, I think now I know.
Since systemd v240 (commit 74c48bf5a8005f20) device access rules
specified as /dev/{block|char}/MM:mm are no longer looked up on the
filesystem, instead, if possible, those are parsed from the string.
So, we need to do different things, depending on systemd version:
- for systemd >= v240, use the /dev/{char,block}/MM:mm as is, without
doing stat() -- since systemd doesn't do stat() either;
- for older version, check if the path exists, and skip passing it on
to systemd otherwise.
- the check for /sys/dev/{block,char}/MM:mm is not needed in either
case.
Pass the systemd version to the function that generates the rules, and
fix it accordingly.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
There is some kind of a race in CentOS 7 which sometimes result in one
of these tests failing like this:
systemd_test.go:136: mkdir /sys/fs/cgroup/hugetlb/system.slice/system-runc_test_pods.slice: no such file or directory
or
systemd_test.go:187: open /sys/fs/cgroup/cpuset/system.slice/system-runc_test_pods.slice/cpuset.mems: no such file or directory
As this is only happening on CentOS 7, let's skip this test on this
platform.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
centos-9 unit test sometimes fails with:
=== RUN TestPodSkipDevicesUpdate
systemd_test.go:114: container stderr not empty: basename: missing operand
Try 'basename --help' for more information.
--- FAIL: TestPodSkipDevicesUpdate (0.11s)
I'm not sure why the container output is an error in basename. It seems
likely that the bashrc in that distro is kind of broken. Let's just run
a sleep command and forget about bash.
Signed-off-by: Rodrigo Campos <rodrigoca@microsoft.com>
This is a forward port of https://github.com/opencontainers/runc/pull/3620
The original code depended on the origin filesystem to have
/dev/{block,char} populated. This is done by udev normally and while is
very common non-containerized systemd installs, it's very easy to start
systemd in a container created by runc itself and not have
/dev/{block,char} populated. When this occurs, the following error
output is observed:
$ docker run hello-world
docker: Error response from daemon: failed to create shim task: OCI runtime create failed: runc create failed: unable to start container process: error during container init: error reopening /dev/null inside container: open /dev/null: operation not permitted: unknown.
/dev/null can't be opened because it was not added to the
deviceAllowList, as there was no /dev/char directory. The change here
utilizes the fact that when sysfs in in use, there is a
/sys/dev/{block,char} that is kernel maintained that we can check.
Signed-off-by: Evan Phoenix <evan@phx.io>
A regression reported for runc v1.1.3 says that "runc exec -t" fails
after doing "systemctl daemon-reload":
> exec failed: unable to start container process: open /dev/pts/0: operation not permitted: unknown
Apparently, with commit 7219387eb7 we are no longer adding
"DeviceAllow=char-pts rwm" rule (because os.Stat("char-pts") returns
ENOENT).
The bug can only be seen after "systemctl daemon-reload" because runc
also applies the same rules manually (by writing to devices.allow for
cgroup v1), and apparently reloading systemd leads to re-applying the
rules that systemd has (thus removing the char-pts access).
The fix is to do os.Stat only for "/dev" paths.
Also, emit a warning that the path was skipped. Since the original idea
was to emit less warnings, demote the level to debug.
Note this also fixes the issue of not adding "m" permission for block-*
and char-* devices.
A test case is added, which reliably fails before the fix
on both cgroup v1 and v2.
Fixes: https://github.com/opencontainers/runc/issues/3551
Fixes: 7219387eb7
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Since Go 1.19, godoc recognizes lists, code blocks, headings etc. It
also reformats the sources making it more apparent that these features
are used.
Fix a few places where it misinterpreted the formatting (such as
indented vs unindented), and format the result using the gofumpt
from HEAD, which already incorporates gofmt 1.19 changes.
Some more fixes (and enhancements) might be required.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
systemd emits very loud warnings when the path specified doesn't exist
(which can be the case for some of our default rules). We don't need the
ruleset we give systemd to be completely accurate (we discard some kinds
of wildcard rules anyway) so we can safely skip adding these.
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
These are only used from inside the package, and we don't want them to
be public.
The only two methods left are Enable and Disable.
While at it, fix or suppress found lint-extra warnings.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This commit separates the functionality of setting cgroup device
rules out of libct/cgroups to libct/cgroups/devices package. This
package, if imported, sets the function variables in libct/cgroups and
libct/cgroups/systemd, so that a cgroup manager can use those to manage
devices. If those function variables are nil (when libct/cgroups/devices
are not imported), a cgroup manager returns the ErrDevicesUnsupported
in case any device rules are set in Resources.
It also consolidates the code from libct/cgroups/ebpf and
libct/cgroups/ebpf/devicefilter into libct/cgroups/devices.
Moved some tests in libct/cg/sd that require device management to
libct/sd/devices.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Only some libcontainer packages can be built on non-linux platforms
(not that it make sense, but at least go build succeeds). Let's call
these "good" packages.
For all other packages (i.e. ones that fail to build with GOOS other
than linux), it does not make sense to have linux build tag (as they
are broken already, and thus are not and can not be used on anything
other than Linux).
Remove linux build tag for all non-"good" packages.
This was mostly done by the following script, with just a few manual
fixes on top.
function list_good_pkgs() {
for pkg in $(find . -type d -print); do
GOOS=freebsd go build $pkg 2>/dev/null \
&& GOOS=solaris go build $pkg 2>/dev/null \
&& echo $pkg
done | sed -e 's|^./||' | tr '\n' '|' | sed -e 's/|$//'
}
function remove_tag() {
sed -i -e '\|^// +build linux$|d' $1
go fmt $1
}
SKIP="^("$(list_good_pkgs)")"
for f in $(git ls-files . | grep .go$); do
if echo $f | grep -qE "$SKIP"; then
echo skip $f
continue
fi
echo proc $f
remove_tag $f
done
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This reverts commit 814f3ae1d9. This
changed the on-disk state which breaks runc when it has to operate on
containers started with an older runc version. Working around this is
far more complicated than just reverting it.
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Looking into data generated by setting
GODEBUG="inittrace=1"
I have noticed this line:
init github.com/opencontainers/runc/libcontainer/cgroups/devices @1.2 ms, 0.020 ms clock, 10512 bytes, 133 allocs
This is the leader for both bytes and allocs among the packages from
this repo, and all of it is caused by a single regex:
> var devicesListRegexp = regexp.MustCompile(`^([abc])\s+(\d+|\*):(\d+|\*)\s+([rwm]+)$`)
It seems that the same parsing can be done without relying on
a regular expression, no decrease in readability, and 2x faster
(according to the benchmark added), and also makes runc start
slightly faster and leaner.
Before:
BenchmarkParseLine-4 176240 6768 ns/op 6576 B/op 64 allocs/op
After:
BenchmarkParseLine-4 322441 3535 ns/op 5520 B/op 53 allocs/op
[v2: single split with SplitFunc; fix a typo in error message]
[v3: rebase after 3159 merge; re-ran benchmarks (results are similar)]
Co-authored-by: Sebastiaan van Stijn <github@gone.nl>
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
The two exceptions I had to add to codespellrc are:
- CLOS (used by intelrtd);
- creat (syscall name used in tests/integration/testdata/seccomp_*.json).
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Possibly there was a specific reason to use a rune for this, but I noticed
that there's various parts in the code that has to convert values from a
string to this type. Using a string as type for this can simplify some of
that code.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
libcontainer/cgroups/devices/devices_emulator.go:261:9: `if` block ends with a `return` statement, so drop this `else` and outdent its block (golint)
} else {
^
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
The devices cgroup emulator is also useful for removing unneeded rules
as well as computing what the final default-allow state of the filter
will be (allow-list or deny-list).
Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
Move the Device-related types to libcontainer/devices, so that
the package can be used in isolation. Aliases have been created
in libcontainer/configs for backward compatibility.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
It seems we missed that systemd added support for the devices cgroup, as
a result systemd would actually *write an allow-all rule each time you
did 'runc update'* if you used the systemd cgroup driver. This is
obviously ... bad and was a clear security bug. Luckily the commits which
introduced this were never in an actual runc release.
So we simply generate the cgroupv1-style rules (which is what systemd's
DeviceAllow wants) and default to a deny-all ruleset. Unfortunately it
turns out that systemd is susceptible to the same spurrious error
failure that we were, so that problem is out of our hands for systemd
cgroup users.
However, systemd has a similar bug to the one fixed in [1]. It will
happily write a disruptive deny-all rule when it is not necessary.
Unfortunately, we cannot even use devices.Emulator to generate a minimal
set of transition rules because the DBus API is limited (you can only
clear or append to the DeviceAllow= list -- so we are forced to always
clear it). To work around this, we simply freeze the container during
SetUnitProperties.
[1]: afe83489d4 ("cgroupv1: devices: use minimal transition rules with devices.Emulator")
Fixes: 1d4ccc8e0c ("fix data inconsistent when runc update in systemd driven cgroup v1")
Fixes: 7682a2b2a5 ("fix data inconsistent when runc update in systemd driven cgroup v2")
Signed-off-by: Aleksa Sarai <asarai@suse.de>
Okay, this requires a bit of explanation.
The reason for this emulation is to allow us to have seamless updates of
the devices cgroup for running containers. This was triggered by several
users having issues where our initial writing of a deny-all rule (in all
cases) results in spurrious errors.
The obvious solution would be to just remove the deny-all rule, right?
Well, it turns out that runc doesn't actually control the deny-all rule
because all users of runc have explicitly specified their own deny-all
rule for many years. This appears to have been done to work around a bug
in runc (which this series has fixed in [1]) where we would actually act
as a black-list despite this being a violation of the OCI spec.
This means that not adding our own deny-all rule in the case of updates
won't solve the issue. However, it will also not solve the issue in
several other cases (the most notable being where a container is being
switched between default-permission modes).
So in order to handle all of these cases, a way of tracking the relevant
internal cgroup state (given a certain state of "cgroups.list" and a set
of rules to apply) is necessary. That is the purpose of DevicesEmulator.
Reading "devices.list" is quite important because that's the only way we
can tell if it's safe to skip the troublesome deny-all rules without
making potentially-dangerous assumptions about the container.
We also are currently bug-compatible with the devices cgroup (namely,
removing rules that don't exist or having superfluous rules all works as
with the in-kernel implementation). The only exception to this is that
we give an error if a user requests to revoke part of a wildcard
exception, because allowing such configurations could result in security
holes (cgroupv1 silently ignores such rules, meaning in white-list mode
that the access is still permitted).
[1]: b2bec9806f ("cgroup: devices: eradicate the Allow/Deny lists")
Signed-off-by: Aleksa Sarai <asarai@suse.de>
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