test: enable test_wait_next_exit

[matejvasek]

Does this PR introduce a user-facing change?

None

[rhatdan]

Seems like it is still broken in CI.

[vrothberg]

@matejvasek did you find time to analyze what's up?

[matejvasek]

@vrothberg this test should be enabled once updated SELinux policy package is available in testing OS.

The fix PR: containers/container-selinux#196
It should be available in SELinux policy package v2.193.0.

I find it odd it is not present, it's been quite a time since fix.

[matejvasek]

@rhatdan @vrothberg the test runs on fedora-37 I would expect that it has container-selinux v2.193.0+.

[matejvasek]

It has container-selinux-2.201.0-1.fc37-noarch so I have no idea why this is failing.

[matejvasek]

I can reproduce the issue locally with container-selinux-2.199. This is weird the write to tmpfs should have been fixed.

Mar 28 21:34:37 bellatrix podman[1509235]: 2023-03-28 21:34:37.176807527 +0200 CEST m=+4.987029737 container init 24c08a537ad9a5116e89a1a0e516c7cf352120e8ff5ced34b0054c1c98d383be (image=quay.io/libpod/alpine:latest, name=top)
Mar 28 21:34:37 bellatrix podman[1509235]: 2023-03-28 21:34:37.180976599 +0200 CEST m=+4.991198809 container start 24c08a537ad9a5116e89a1a0e516c7cf352120e8ff5ced34b0054c1c98d383be (image=quay.io/libpod/alpine:latest, name=top)
Mar 28 21:34:37 bellatrix systemd-journald[16005]: Failed to stat passed file, ignoring: Permission denied
Mar 28 21:34:37 bellatrix audit[16005]: AVC avc:  denied  { getattr } for  pid=16005 comm="systemd-journal" path=2F6465762F73686D2F6A6F75726E616C2E585858585831323932393430333935202864656C6574656429 dev="tmpfs" ino=457645 scontext=system_u:system_r:syslogd_t:s0 tcontext=unconfined_u:object_r:container_runtime_tmpfs_t:s0 tclass=file permissive=0
Mar 28 21:34:37 bellatrix audit[16005]: SYSCALL arch=c000003e syscall=262 success=no exit=-13 a0=3b a1=7ff9879b7093 a2=7ffdcca48f10 a3=1000 items=1 ppid=1 pid=16005 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=4294967295 comm="systemd-journal" exe="/usr/lib/systemd/systemd-journald" subj=system_u:system_r:syslogd_t:s0 key=(null)
Mar 28 21:34:37 bellatrix audit: CWD cwd="/"
Mar 28 21:34:37 bellatrix audit: PATH item=0 name="" inode=457645 dev=00:17 mode=0100600 ouid=1000 ogid=1000 rdev=00:00 obj=unconfined_u:object_r:container_runtime_tmpfs_t:s0 nametype=NORMAL cap_fp=0 cap_fi=0 cap_fe=0 cap_fver=0 cap_frootid=0
Mar 28 21:34:37 bellatrix audit: PROCTITLE proctitle="/usr/lib/systemd/systemd-journald"
Mar 28 21:34:37 bellatrix top[1509384]: [83B blob data]
Mar 28 21:34:37 bellatrix top[1509384]: CPU:   8% usr   4% sys   0% nic  84% idle   0% io   1% irq   1% sirq
Mar 28 21:34:37 bellatrix top[1509384]: Load average: 3.29 1.78 1.54 1/4850 1
Mar 28 21:34:37 bellatrix top[1509384]:   PID  PPID USER     STAT   VSZ %VSZ CPU %CPU COMMAND

[matejvasek]

@rhatdan ^^^ any idea what the problem could be?
btw pid 16005 is systemd-journald

[matejvasek]

Before the error was different (different syscall was denied):
OLD ERROR:

dfbd.scope - libcrun container.
Mar 28 21:41:13 bellatrix audit[16005]: AVC avc:  denied  { read write } for  pid=16005 comm="systemd-journal" path=2F6465762F73686D2F6A6F75726E616C2E585858585833373730313431383132202864656C6574656429 dev="tmpfs" ino=459577 scontext=system_u:system_r:syslogd_t:s0 tcontext=unconfined_u:object_r:container_runtime_tmpfs_t:s0 tclass=file permissive=0
Mar 28 21:41:13 bellatrix audit[16005]: SYSCALL arch=c000003e syscall=47 success=yes exit=0 a0=5 a1=7ffdcca48de0 a2=40000040 a3=7ffdccb67080 items=0 ppid=1 pid=16005 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=4294967295 comm="systemd-journal" exe="/usr/lib/systemd/systemd-journald" subj=system_u:system_r:syslogd_t:s0 key=(null)
Mar 28 21:41:13 bellatrix audit: SOCKADDR saddr=0100003934356431
Mar 28 21:41:13 bellatrix audit: PROCTITLE proctitle="/usr/lib/systemd/systemd-journald"
Mar 28 21:41:13 bellatrix systemd-journald[16005]: Got message with truncated control data (too many fds sent?), ignoring.
Mar 28 21:41:13 bellatrix audit[16005]: AVC avc:  denied  { read write } for  pid=16005 comm="systemd-journal" path=2F6465762F73686D2F6A6F75726E616C2E585858585833373833353031303335202864656C6574656429 dev="tmpfs" ino=459578 scontext=system_u:system_r:syslogd_t:s0 tcontext=unconfined_u:object_r:container_runtime_tmpfs_t:s0 tclass=file permissive=0
Mar 28 21:41:13 bellatrix audit[16005]: SYSCALL arch=c000003e syscall=47 success=yes exit=0 a0=5 a1=7ffdcca48de0 a2=40000040 a3=7ffdccb67080 items=0 ppid=1 pid=16005 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=4294967295 comm="systemd-journal" exe="/usr/lib/systemd/systemd-journald" subj=system_u:system_r:syslogd_t:s0 key=(null)
Mar 28 21:41:13 bellatrix audit: SOCKADDR saddr=0100003934356431
Mar 28 21:41:13 bellatrix audit: PROCTITLE proctitle="/usr/lib/systemd/systemd-journald"
Mar 28 21:41:13 bellatrix systemd-journald[16005]: Got message with truncated control data (too many fds sent?), ignoring.
Mar 28 21:41:13 bellatrix audit[16005]: AVC avc:  denied  { read write } for  pid=16005 comm="systemd-journal" path=2F6465762F73686D2F6A6F75726E616C2E585858585832353039323238323333202864656C6574656429 dev="tmpfs" ino=459579 scontext=system_u:system_r:syslogd_t:s0 tcontext=unconfined_u:object_r:container_runtime_tmpfs_t:s0 tclass=file permissive=0
Mar 28 21:41:13 bellatrix systemd-journald[16005]: Got message with truncated control data (too many fds sent?), ignoring.
Mar 28 21:41:13 bellatrix audit[16005]: SYSCALL arch=c000003e syscall=47 success=yes exit=0 a0=5 a1=7ffdcca48de0 a2=40000040 a3=7ffdccb67080 items=0 ppid=1 pid=16005 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=4294967295 comm="systemd-journal" exe="/usr/lib/systemd/systemd-journald" subj=system_u:system_r:syslogd_t:s0 key=(null)

[matejvasek]

@rhatdan Maybe some other global SELinux policies changed?

[matejvasek]

cc @edsantiago

[edsantiago]

Whoosh. Way over my head, sorry.

[rhatdan]

Can you get this to fail outside of the CI/CD system?

[rhatdan]

What do I need to do to test this locally?

[matejvasek]

@rhatdan

# in podman project
python3 -m venv venv
source ./venv/bin/activate
pip3 install -r test/python/requirements.txt
export PODMAN=/path/to/podman
python -m unittest test.python.docker.compat.test_containers.TestContainers.test_wait_next_exit

[matejvasek]

Sometimes the testing podman service hangs:

subprocess.CalledProcessError: Command 'podman system service' returned non-zero exit status 125.

in such a case kill it manually.

[matejvasek]

@rhatdan or just run a container with an image with 200k long labels an look into syslog.

[matejvasek]

@rhatdan try this:
podman run --rm quay.io/mvasek/long-label:latest and then check journalctl -f.

[matejvasek]

@rhatdan have you managed to reproduce the issue?

[matejvasek]

@rhatdan I don't know if it helps but: the AVC denied error happens when len(labels) around 104k-105k characters. For instance 100k label does work all right.

[matejvasek]

Before containers/container-selinux#196 the limit was just few 10k IIRC.

[matejvasek]

The good news for me is the image we use has labels just very little bit above 100k so it working for my use-case.
Still I with there were some reserve hence the test uses 250k labels.

[rhatdan]

I really have no idea what is going on here.

[matejvasek]

Something more from investigation:

Larges message that can be sent to log is 212940 bytes.

What is most likely happening:

• Try send log entry by ssize_t send(int sockfd, const void *buf, size_t len, int flags), if succeeded we are done.
• If the above fails due to EMSGSIZE try ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags),
  the msghdr struct contains contains file-descriptor to temp file created by podman in /dev/shm.
  The call succeeds, however systemd-journald cannot access the temp file and it gets AVC.

The SELinux labels of the temp file unconfined_u:object_r:container_runtime_tmpfs_t:s0.
The SELinux labels of the systemd-journald daemon system_u:system_r:syslogd_t:s0.

[matejvasek]

@rhatdan @edsantiago I added some new findings above.

[matejvasek]

simple reproducer:

var err error
msgLen := 212_940 + 1
data := make([]byte, msgLen)
for i := range data {
	data[i] = '0'
}
err = journal.Send(string(data[:msgLen]), journal.PriInfo, nil)
if err != nil {
	t.Fatal(err)
}

don't forget to set chcon on the testing binary.

[rhatdan]

container-selinux-2.209.0 should fix this.

[edsantiago]

There's a new CI VM build in progress, expected for next week maybe. f37 includes container-selinux-209 but unfortunately f36 does not

[matejvasek]

The Docker-py Compat. test runs on F37, support for F36 ends mid May so I think it's fine.

[edsantiago]

@matejvasek re-pushing isn't going to do any good if you don't rebase. The magic you need is in .cirrus.yml and was merged in #18124.

[matejvasek]

@rhatdan @edsantiago Thanks. It should be all right now.

[edsantiago]

I think this is the test in question?. It passed (all tests pass), and shows container-selinux-2.209 present, so I guess this is good to go?

/approve

@rhatdan PTAL.

[openshift-ci]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: edsantiago, matejvasek

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[rhatdan]

/lgtm
Thanks @matejvasek