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| author |   Jiri Olsa <jolsa@redhat.com> | 2022-01-04 13:10:30 +0100 |
|---|---|---|
| committer |   Daniel Borkmann <daniel@iogearbox.net> | 2022-01-05 13:35:18 +0100 |
| commit | 5e22dd18626726028a93ff1350a8a71a00fd843d (patch) | |
| tree | 4df240cc9db3542f7f3323c8ab16c926cb36b3bc /tools/testing/selftests/bpf/prog_tests/tc_redirect.c | |
| parent | bpftool: Probe for instruction set extensions (diff) | |
| download | linux-dev-5e22dd18626726028a93ff1350a8a71a00fd843d.tar.xz linux-dev-5e22dd18626726028a93ff1350a8a71a00fd843d.zip | |
bpf/selftests: Fix namespace mount setup in tc_redirect
The tc_redirect umounts /sys in the new namespace, which can be
mounted as shared and cause global umount. The lazy umount also
takes down mounted trees under /sys like debugfs, which won't be
available after sysfs mounts again and could cause fails in other
tests.
# cat /proc/self/mountinfo | grep debugfs
34 23 0:7 / /sys/kernel/debug rw,nosuid,nodev,noexec,relatime shared:14 - debugfs debugfs rw
# cat /proc/self/mountinfo | grep sysfs
23 86 0:22 / /sys rw,nosuid,nodev,noexec,relatime shared:2 - sysfs sysfs rw
# mount | grep debugfs
debugfs on /sys/kernel/debug type debugfs (rw,nosuid,nodev,noexec,relatime)
# ./test_progs -t tc_redirect
#164 tc_redirect:OK
Summary: 1/4 PASSED, 0 SKIPPED, 0 FAILED
# mount | grep debugfs
# cat /proc/self/mountinfo | grep debugfs
# cat /proc/self/mountinfo | grep sysfs
25 86 0:22 / /sys rw,relatime shared:2 - sysfs sysfs rw
Making the sysfs private under the new namespace so the umount won't
trigger the global sysfs umount.
Reported-by: Hangbin Liu <haliu@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jussi Maki <joamaki@gmail.com>
Link: https://lore.kernel.org/bpf/20220104121030.138216-1-jolsa@kernel.org
Diffstat (limited to '')
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/tc_redirect.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/tc_redirect.c b/tools/testing/selftests/bpf/prog_tests/tc_redirect.c index 4b18b73df10b..c2426df58e17 100644 --- a/tools/testing/selftests/bpf/prog_tests/tc_redirect.c +++ b/tools/testing/selftests/bpf/prog_tests/tc_redirect.c @@ -105,6 +105,13 @@ static int setns_by_fd(int nsfd) if (!ASSERT_OK(err, "unshare")) return err; + /* Make our /sys mount private, so the following umount won't + * trigger the global umount in case it's shared. + */ + err = mount("none", "/sys", NULL, MS_PRIVATE, NULL); + if (!ASSERT_OK(err, "remount private /sys")) + return err; + err = umount2("/sys", MNT_DETACH); if (!ASSERT_OK(err, "umount2 /sys")) return err; |