linux-kernel - Re: [PATCH v1] selftests: add binderfs selftests

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Message-ID: <20190117102515.lnzjohxwk3bms5gr@brauner.io>
Date:   Thu, 17 Jan 2019 11:25:16 +0100
From:   Christian Brauner <christian@...uner.io>
To:     shuah <shuah@...nel.org>
Cc:     gregkh@...uxfoundation.org, tkjos@...roid.com,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, arve@...roid.com,
        maco@...roid.com, joel@...lfernandes.org, tkjos@...gle.com
Subject: Re: [PATCH v1] selftests: add binderfs selftests

On Wed, Jan 16, 2019 at 04:11:55PM -0700, shuah wrote:
> Hi Christian,
> 
> On 1/16/19 3:27 PM, Christian Brauner wrote:
> > This adds the promised selftest for binderfs. It will verify the following
> > things:
> > - binderfs mounting works
> > - binder device allocation works
> > - performing a binder ioctl() request through a binderfs device works
> > - binder device removal works
> > - binder-control removal fails
> > - binderfs unmounting works
> > 
> 
> Thanks for the patch. A few comments below.

Thanks for the review!

> 
> > Cc: Todd Kjos <tkjos@...gle.com>
> > Signed-off-by: Christian Brauner <christian.brauner@...ntu.com>
> > ---
> > /* Changelog */
> > 
> > v1:
> > - check for ENODEV on mount failure to detect whether binderfs is
> >    available
> >    If it is not, skip the test and exit with success.
> > ---
> >   tools/testing/selftests/Makefile              |   1 +
> >   .../selftests/filesystems/binderfs/.gitignore |   1 +
> >   .../selftests/filesystems/binderfs/Makefile   |   6 +
> >   .../filesystems/binderfs/binderfs_test.c      | 126 ++++++++++++++++++
> >   .../selftests/filesystems/binderfs/config     |   3 +
> >   5 files changed, 137 insertions(+)
> >   create mode 100644 tools/testing/selftests/filesystems/binderfs/.gitignore
> >   create mode 100644 tools/testing/selftests/filesystems/binderfs/Makefile
> >   create mode 100644 tools/testing/selftests/filesystems/binderfs/binderfs_test.c
> >   create mode 100644 tools/testing/selftests/filesystems/binderfs/config
> > 
> > diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
> > index 1a2bd15c5b6e..400ee81a3043 100644
> > --- a/tools/testing/selftests/Makefile
> > +++ b/tools/testing/selftests/Makefile
> > @@ -10,6 +10,7 @@ TARGETS += drivers/dma-buf
> >   TARGETS += efivarfs
> >   TARGETS += exec
> >   TARGETS += filesystems
> > +TARGETS += filesystems/binderfs
> >   TARGETS += firmware
> >   TARGETS += ftrace
> >   TARGETS += futex
> > diff --git a/tools/testing/selftests/filesystems/binderfs/.gitignore b/tools/testing/selftests/filesystems/binderfs/.gitignore
> > new file mode 100644
> > index 000000000000..8a5d9bf63dd4
> > --- /dev/null
> > +++ b/tools/testing/selftests/filesystems/binderfs/.gitignore
> > @@ -0,0 +1 @@
> > +binderfs_test
> > diff --git a/tools/testing/selftests/filesystems/binderfs/Makefile b/tools/testing/selftests/filesystems/binderfs/Makefile
> > new file mode 100644
> > index 000000000000..58cb659b56b4
> > --- /dev/null
> > +++ b/tools/testing/selftests/filesystems/binderfs/Makefile
> > @@ -0,0 +1,6 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +
> > +CFLAGS += -I../../../../../usr/include/
> > +TEST_GEN_PROGS := binderfs_test
> > +
> > +include ../../lib.mk
> > diff --git a/tools/testing/selftests/filesystems/binderfs/binderfs_test.c b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
> > new file mode 100644
> > index 000000000000..34361efcb9c8
> > --- /dev/null
> > +++ b/tools/testing/selftests/filesystems/binderfs/binderfs_test.c
> > @@ -0,0 +1,126 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +
> > +#define _GNU_SOURCE
> > +#include <errno.h>
> > +#include <fcntl.h>
> > +#include <sched.h>
> > +#include <stdio.h>
> > +#include <stdlib.h>
> > +#include <string.h>
> > +#include <sys/ioctl.h>
> > +#include <sys/mount.h>
> > +#include <sys/stat.h>
> > +#include <sys/types.h>
> > +#include <unistd.h>
> > +#include <linux/android/binder.h>
> > +#include <linux/android/binderfs.h>
> > +#include "../../kselftest.h"
> > +
> > +int main(int argc, char *argv[])
> > +{
> > +	int fd, ret, saved_errno;
> > +	size_t len;
> > +	struct binderfs_device device = { 0 };
> > +	struct binder_version version = { 0 };
> > +
> > +	ret = unshare(CLONE_NEWNS);
> > +	if (ret < 0)
> > +		ksft_exit_fail_msg("%s - Failed to unshare mount namespace\n",
> > +				   strerror(errno));
> > +
> > +	ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0);
> > +	if (ret < 0)
> > +		ksft_exit_fail_msg("%s - Failed to mount / as private\n",
> > +				   strerror(errno));
> > +
> 
> If this test requires user to be root, please add check for root uid and
> do a skip the test with kselftest skip code.

I think in addition to privileged tests I'll also add unprivileged tests
when mounting binderfs inside a user namespace so that we a) can run
this test as an unprivileged user and b) test that binderfs is mountable
in user namespaces.

> 
> > +	ret = mkdir("/dev/binderfs", 0755);
> > +	if (ret < 0 && errno != EEXIST)
> > +		ksft_exit_fail_msg(
> > +			"%s - Failed to create binderfs mountpoint\n",
> > +			strerror(errno));
> > +
> > +	ret = mount(NULL, "/dev/binderfs", "binder", 0, 0);
> > +	if (ret < 0) {
> > +		if (errno != ENODEV)
> > +			ksft_exit_fail_msg("%s - Failed to mount binderfs\n",
> > +					   strerror(errno));
> > +
> > +		ksft_test_result_skip(
> > +			"The Android binderfs filesystem is not available\n")
> 
> Use ksft_exit_skip() instead of ksft_test_result_skip()
> 
> > +		ksft_exit_pass();
> 
> ksft_exit_pass() would result in false pass cases. Skip is the correct
> exit code.

Thanks, fixed now.

Christian