Re: [PATCH 09/12] sysctl: move cad_pid into kernel/pid.c

[Joel Granados <joel.granados@kernel.org>]

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On Fri, May 09, 2025 at 12:01:24PM -0700, Kees Cook wrote:
> On Fri, May 09, 2025 at 02:54:13PM +0200, Joel Granados wrote:
> > Move cad_pid as well as supporting function proc_do_cad_pid into
> > kernel/pic.c. Replaced call to __do_proc_dointvec with proc_dointvec
> > inside proc_do_cad_pid which requires the copy of the ctl_table to
> > handle the temp value.
> > 
> > This is part of a greater effort to move ctl tables into their
> > respective subsystems which will reduce the merge conflicts in
> > kernel/sysctl.c.
> > 
> > Signed-off-by: Joel Granados <joel.granados@kernel.org>
> > ---
> >  kernel/pid.c    | 32 ++++++++++++++++++++++++++++++++
> >  kernel/sysctl.c | 31 -------------------------------
> >  2 files changed, 32 insertions(+), 31 deletions(-)
> > 
> > diff --git a/kernel/pid.c b/kernel/pid.c
> > index 4ac2ce46817fdefff8888681bb5ca3f2676e8add..bc87ba08ae8b7c67f3457b31309b56b5d90f8c52 100644
> > --- a/kernel/pid.c
> > +++ b/kernel/pid.c
> > @@ -717,6 +717,29 @@ static struct ctl_table_root pid_table_root = {
> >  	.set_ownership	= pid_table_root_set_ownership,
> >  };
> >  
> > +static int proc_do_cad_pid(const struct ctl_table *table, int write, void *buffer,
> > +		size_t *lenp, loff_t *ppos)
> > +{
> > +	struct pid *new_pid;
> > +	pid_t tmp_pid;
> > +	int r;
> > +	struct ctl_table tmp_table = *table;
> > +
> > +	tmp_pid = pid_vnr(cad_pid);
> > +	tmp_table.data = &tmp_pid;
> > +
> > +	r = proc_dointvec(&tmp_table, write, buffer, lenp, ppos);
> > +	if (r || !write)
> > +		return r;
> > +
> > +	new_pid = find_get_pid(tmp_pid);
> > +	if (!new_pid)
> > +		return -ESRCH;
> > +
> > +	put_pid(xchg(&cad_pid, new_pid));
> > +	return 0;
> > +}
> > +
> >  static const struct ctl_table pid_table[] = {
> >  	{
> >  		.procname	= "pid_max",
> > @@ -727,6 +750,15 @@ static const struct ctl_table pid_table[] = {
> >  		.extra1		= &pid_max_min,
> >  		.extra2		= &pid_max_max,
> >  	},
> > +#ifdef CONFIG_PROC_SYSCTL
> > +	{
> > +		.procname	= "cad_pid",
> > +		.data		= NULL,
> 
> nit: this is redundant, any unspecified member will be zero-initialized.
Thx. Changed it locally, but will not resend for this.
> 
> Regardless:
> 
> Reviewed-by: Kees Cook <kees@kernel.org>
...
> > -		.data		= NULL,
> > -		.maxlen		= sizeof (int),
> > -		.mode		= 0600,
> > -		.proc_handler	= proc_do_cad_pid,
> > -	},
> >  #endif
> >  	{
> >  		.procname	= "overflowuid",
> > 
> > -- 
> > 2.47.2
> > 
> > 
> 
> -- 
> Kees Cook

-- 

Joel Granados

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