Re: [LTP] [PATCH 4/6] Add ioctl_pidfd02 test

[Cyril Hrubis <chrubis@suse.cz>]

Hi!
> diff --git a/runtest/syscalls b/runtest/syscalls
> index 7f6312ce5fa241a778d8dda7f8ee9edd0a8800e6..23f335846663d62a39e6de3a8f6948c1b0acf8a5 100644
> --- a/runtest/syscalls
> +++ b/runtest/syscalls
> @@ -613,6 +613,7 @@ ioctl_ficlonerange02 ioctl_ficlonerange02
>  ioctl_fiemap01 ioctl_fiemap01
>  
>  ioctl_pidfd01 ioctl_pidfd01
> +ioctl_pidfd02 ioctl_pidfd02
>  
>  inotify_init1_01 inotify_init1_01
>  inotify_init1_02 inotify_init1_02
> diff --git a/testcases/kernel/syscalls/ioctl/.gitignore b/testcases/kernel/syscalls/ioctl/.gitignore
> index aa952c1a7bae0ae2dbb04de0595f10d508b6759a..1c81c2bed8db952af0c93fb1ce5bfbad82794b60 100644
> --- a/testcases/kernel/syscalls/ioctl/.gitignore
> +++ b/testcases/kernel/syscalls/ioctl/.gitignore
> @@ -30,3 +30,4 @@
>  /ioctl_ficlonerange02
>  /ioctl_fiemap01
>  /ioctl_pidfd01
> +/ioctl_pidfd02
> diff --git a/testcases/kernel/syscalls/ioctl/ioctl_pidfd02.c b/testcases/kernel/syscalls/ioctl/ioctl_pidfd02.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..82dd8c359938cdc7bf69cc2fd6afc90ce2a95290
> --- /dev/null
> +++ b/testcases/kernel/syscalls/ioctl/ioctl_pidfd02.c
> @@ -0,0 +1,62 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2025 Andrea Cervesato <andrea.cervesato@suse.com>
> + */
> +
> +/*\
> + * Check if the ioctl() function allows retrieval of a child's exit code
> + * using PIDFD_INFO_EXIT from a process that is isolated from the child.
> + */
> +
> +#include "tst_test.h"
> +#include "lapi/pidfd.h"
> +#include "lapi/sched.h"
> +
> +static struct tst_clone_args *args;
> +static struct pidfd_info *info;
> +
> +static void run(void)
> +{
> +	int status;
> +	int pidfd = 0;
> +	pid_t pid_child;
> +
> +	memset(args, 0, sizeof(struct tst_clone_args));
> +
> +	args->flags = CLONE_PIDFD | CLONE_NEWUSER | CLONE_NEWPID;
> +	args->pidfd = (uint64_t)&pidfd;
> +	args->exit_signal = SIGCHLD;
> +
> +	pid_child = SAFE_CLONE(args);
> +	if (!pid_child) {
> +		TST_CHECKPOINT_WAIT(0);
> +		exit(100);
> +	}
> +
> +	/* child is not reaped, so ioctl() will pass */
> +	info->mask = 0;
> +	SAFE_IOCTL(pidfd, PIDFD_GET_INFO, info);


It will pass and:

- fill in some fields unconditionally
 - if PIDFD_INFO_CREDS is set the info.*{uid,gid} should be checked
 - if PIDFD_INFO_PID is set the info.*pid should be checked
 - if PIDFD_INFO_CGROUPID is set the info.cgroupid will be also set

- the PIDFD_INFO_EXIT flag will not be set before the process did exit



> +	TST_CHECKPOINT_WAKE(0);
> +	SAFE_WAITPID(pid_child, &status, 0);
> +
> +	/* child is now reaped, so we can ask for the exit status */
> +	info->mask = PIDFD_INFO_EXIT;
> +	SAFE_IOCTL(pidfd, PIDFD_GET_INFO, info);
> +
> +	TST_EXP_EQ_LI(info->mask & PIDFD_INFO_EXIT, PIDFD_INFO_EXIT);
> +	TST_EXP_EQ_LI(WIFEXITED(info->exit_code), WIFEXITED(status));
> +	TST_EXP_EQ_LI(WEXITSTATUS(info->exit_code), WEXITSTATUS(status));

And here we should check that we got the same fields set as in the
previous case when the process was still running plus the exit_code.

I suppose that we will need two info structures so that we can do the
comparsion. Also it wouldn't harm to clear the structures with memset
before use.

> +}
> +
> +static struct tst_test test = {
> +	.test_all = run,
> +	.forks_child = 1,
> +	.needs_checkpoints = 1,
> +	.min_kver = "6.15",
> +	.bufs = (struct tst_buffers []) {
> +		{&args, .size = sizeof(*args)},
> +		{&info, .size = sizeof(*info)},
> +		{}
> +	}
> +};
> 
> -- 
> 2.50.0
> 

-- 
Cyril Hrubis
chrubis@suse.cz

-- 
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