[2/3] tracing/selftests: Add tracefs mount options test

Add test to check the tracefs gid mount option is applied correctly

   ./ftracetest test.d/00basic/mount_options.tc

Use the new readme string "[gid=<gid>] as a requirement and also update
test_ownership.tc requirements to use this.

mount_options.tc will fail currently, this is fixed by the subsequent
patch in this series.

Cc: David Howells <dhowells@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
---
 .../ftrace/test.d/00basic/mount_options.tc    | 101 ++++++++++++++++++
 .../ftrace/test.d/00basic/test_ownership.tc   |  16 +--
 .../testing/selftests/ftrace/test.d/functions |  25 +++++
 3 files changed, 129 insertions(+), 13 deletions(-)
 create mode 100644 tools/testing/selftests/ftrace/test.d/00basic/mount_options.tc

On Mon, Oct 28, 2024 at 4:23 PM Kalesh Singh <kaleshsingh@google.com> wrote:
>
> On Mon, Oct 28, 2024 at 4:14 PM Steven Rostedt <rostedt@goodmis.org> wrote:
> >
> > On Mon, 28 Oct 2024 14:43:58 -0700
> > Kalesh Singh <kaleshsingh@google.com> wrote:
> >
> > > Add test to check the tracefs gid mount option is applied correctly
> > >
> > >    ./ftracetest test.d/00basic/mount_options.tc
> > >
> > > Use the new readme string "[gid=<gid>] as a requirement and also update
> > > test_ownership.tc requirements to use this.
> > >
> > > mount_options.tc will fail currently, this is fixed by the subsequent
> > > patch in this series.
> >
> > Test cases should never be added when they can fail. They should always
> > come after the fix is applied. But it appears that you check the README
> > to make sure that it does work and not fail.
> >
> > I'll take a look at these patches in more detail later.
>
> Hi Steve,
>
> Thank you for the quick reviews, please feel free to ignore until you are back.
>
> I'll address these comments and resend a v2.

I've posted v2 at:
https://lore.kernel.org/r/20241030171928.4168869-1-kaleshsingh@google.com/

Thanks,
Kalesh

>
> Thanks,
> Kalesh
>
> >
> > Thanks,
> >
> > -- Steve
> >
> >
> > >
> > > Cc: David Howells <dhowells@redhat.com>
> > > Cc: Steven Rostedt <rostedt@goodmis.org>
> > > Cc: Masami Hiramatsu <mhiramat@kernel.org>
> > > Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
> > > ---
> > >  .../ftrace/test.d/00basic/mount_options.tc    | 101 ++++++++++++++++++
> > >  .../ftrace/test.d/00basic/test_ownership.tc   |  16 +--
> > >  .../testing/selftests/ftrace/test.d/functions |  25 +++++
> > >  3 files changed, 129 insertions(+), 13 deletions(-)
> > >  create mode 100644 tools/testing/selftests/ftrace/test.d/00basic/mount_options.tc
> > >
> > > diff --git a/tools/testing/selftests/ftrace/test.d/00basic/mount_options.tc b/tools/testing/selftests/ftrace/test.d/00basic/mount_options.tc
> > > new file mode 100644
> > > index 000000000000..b8aff85ec259
> > > --- /dev/null
> > > +++ b/tools/testing/selftests/ftrace/test.d/00basic/mount_options.tc
> > > @@ -0,0 +1,101 @@
> > > +#!/bin/sh
> > > +# SPDX-License-Identifier: GPL-2.0
> > > +# description: Test tracefs GID mount option
> > > +# requires: "[gid=<gid>]":README
> > > +
> > > +fail() {
> > > +     local msg="$1"
> > > +
> > > +     echo "FAILED: $msg"
> > > +     exit_fail
> > > +}
> > > +
> > > +find_alternate_gid() {
> > > +     local original_gid="$1"
> > > +     tac /etc/group | grep -v ":$original_gid:" | head -1 | cut -d: -f3
> > > +}
> > > +
> > > +mount_tracefs_with_options() {
> > > +     local mount_point="$1"
> > > +     local options="$2"
> > > +
> > > +     mount -t tracefs -o "$options" nodev "$mount_point"
> > > +
> > > +     setup
> > > +}
> > > +
> > > +unmount_tracefs() {
> > > +     local mount_point="$1"
> > > +
> > > +     # Need to make sure the mount isn't busy so that we can umount it
> > > +     (cd $mount_point; finish_ftrace;)
> > > +
> > > +     cleanup
> > > +}
> > > +
> > > +create_instance() {
> > > +     local mount_point="$1"
> > > +     local instance="$mount_point/instances/$(mktemp -u test-XXXXXX)"
> > > +
> > > +     mkdir "$instance"
> > > +     echo "$instance"
> > > +}
> > > +
> > > +remove_instance() {
> > > +     local instance="$1"
> > > +
> > > +     rmdir "$instance"
> > > +}
> > > +
> > > +check_gid() {
> > > +     local mount_point="$1"
> > > +     local expected_gid="$2"
> > > +
> > > +     echo "Checking permission group ..."
> > > +
> > > +     cd "$mount_point"
> > > +
> > > +     for file in "." "events" "events/sched" "events/sched/sched_switch" "events/sched/sched_switch/enable"; do
> > > +             local gid=`stat -c "%g" $file`
> > > +             if [ "$gid" -ne "$expected_gid" ]; then
> > > +                     cd - # Return to the previous working direcotry (tracefs root)
> > > +                     fail "$(realpath $file): Expected group $expected_gid; Got group $gid"
> > > +             fi
> > > +     done
> > > +
> > > +     cd - # Return to the previous working direcotry (tracefs root)
> > > +}
> > > +
> > > +test_gid_mount_option() {
> > > +     local mount_point=$(get_mount_point)
> > > +     local mount_options=$(get_mnt_options "$mount_point")
> > > +     local original_group=$(stat -c "%g" .)
> > > +     local other_group=$(find_alternate_gid "$original_group")
> > > +
> > > +     # Set up mount options with new GID for testing
> > > +     local new_options=`echo "$mount_options" | sed -e "s/gid=[0-9]*/gid=$other_group/"`
> > > +     if [ "$new_options" = "$mount_options" ]; then
> > > +             new_options="$mount_options,gid=$other_group"
> > > +             mount_options="$mount_options,gid=$original_group"
> > > +     fi
> > > +
> > > +     # Unmount existing tracefs instance and mount with new GID
> > > +     unmount_tracefs "$mount_point"
> > > +     mount_tracefs_with_options "$mount_point" "$new_options"
> > > +
> > > +     check_gid "$mount_point" "$other_group"
> > > +
> > > +     # Check that files created after the mount inherit the GID
> > > +     local instance=$(create_instance "$mount_point")
> > > +     check_gid "$instance" "$other_group"
> > > +     remove_instance "$instance"
> > > +
> > > +     # Unmount and remount with the original GID
> > > +     unmount_tracefs "$mount_point"
> > > +     mount_tracefs_with_options "$mount_point" "$mount_options"
> > > +     check_gid "$mount_point" "$original_group"
> > > +}
> > > +
> > > +test_gid_mount_option
> > > +
> > > +exit 0
> > > diff --git a/tools/testing/selftests/ftrace/test.d/00basic/test_ownership.tc b/tools/testing/selftests/ftrace/test.d/00basic/test_ownership.tc
> > > index 094419e190c2..e71cc3ad0bdf 100644
> > > --- a/tools/testing/selftests/ftrace/test.d/00basic/test_ownership.tc
> > > +++ b/tools/testing/selftests/ftrace/test.d/00basic/test_ownership.tc
> > > @@ -1,24 +1,14 @@
> > >  #!/bin/sh
> > >  # SPDX-License-Identifier: GPL-2.0
> > >  # description: Test file and directory ownership changes for eventfs
> > > +# requires: "[gid=<gid>]":README
> > >
> > >  original_group=`stat -c "%g" .`
> > >  original_owner=`stat -c "%u" .`
> > >
> > > -mount_point=`stat -c '%m' .`
> > > +local mount_point=$(get_mount_point)
> > >
> > > -# If stat -c '%m' does not work (e.g. busybox) or failed, try to use the
> > > -# current working directory (which should be a tracefs) as the mount point.
> > > -if [ ! -d "$mount_point" ]; then
> > > -     if mount | grep -qw $PWD ; then
> > > -             mount_point=$PWD
> > > -     else
> > > -             # If PWD doesn't work, that is an environmental problem.
> > > -             exit_unresolved
> > > -     fi
> > > -fi
> > > -
> > > -mount_options=`mount | grep "$mount_point" | sed -e 's/.*(\(.*\)).*/\1/'`
> > > +mount_options=$(get_mnt_options "$mount_point")
> > >
> > >  # find another owner and group that is not the original
> > >  other_group=`tac /etc/group | grep -v ":$original_group:" | head -1 | cut -d: -f3`
> > > diff --git a/tools/testing/selftests/ftrace/test.d/functions b/tools/testing/selftests/ftrace/test.d/functions
> > > index 779f3e62ec90..84d6a9c7ad67 100644
> > > --- a/tools/testing/selftests/ftrace/test.d/functions
> > > +++ b/tools/testing/selftests/ftrace/test.d/functions
> > > @@ -193,3 +193,28 @@ ftrace_errlog_check() { # err-prefix command-with-error-pos-by-^ command-file
> > >      # "  Command: " and "^\n" => 13
> > >      test $(expr 13 + $pos) -eq $N
> > >  }
> > > +
> > > +# Helper to get the tracefs mount point
> > > +get_mount_point() {
> > > +     local mount_point=`stat -c '%m' .`
> > > +
> > > +     # If stat -c '%m' does not work (e.g. busybox) or failed, try to use the
> > > +     # current working directory (which should be a tracefs) as the mount point.
> > > +     if [ ! -d "$mount_point" ]; then
> > > +             if mount | grep -qw "$PWD"; then
> > > +                     mount_point=$PWD
> > > +             else
> > > +                     # If PWD doesn't work, that is an environmental problem.
> > > +                     exit_unresolved
> > > +             fi
> > > +     fi
> > > +     echo "$mount_point"
> > > +}
> > > +
> > > +# Helper function to retrieve mount options for a given mount point
> > > +get_mnt_options() {
> > > +     local mnt_point="$1"
> > > +     local opts=$(mount | grep -m1 "$mnt_point" | sed -e 's/.*(\(.*\)).*/\1/')
> > > +
> > > +     echo "$opts"
> > > +}
> > > \ No newline at end of file
> >