linux-kernel - Re: [PATCH 5/5] sysctl: pass kernel pointers to ->proc

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Date:   Fri, 24 Apr 2020 12:06:50 -0700
From:   Andrey Ignatov <rdna@...com>
To:     Christoph Hellwig <hch@....de>
CC:     Kees Cook <keescook@...omium.org>,
        Iurii Zaikin <yzaikin@...gle.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        <linux-fsdevel@...r.kernel.org>, <netdev@...r.kernel.org>,
        <bpf@...r.kernel.org>
Subject: Re: [PATCH 5/5] sysctl: pass kernel pointers to ->proc_handler

Christoph Hellwig <hch@....de> [Thu, 2020-04-23 23:44 -0700]:
> Instead of having all the sysctl handlers deal with user pointers, which
> is rather hairy in terms of the BPF interaction, copy the input to and
> from  userspace in common code.  This also means that the strings are
> always NUL-terminated by the common code, making the API a little bit
> safer.
> 
> As most handler just pass through the data to one of the common handlers
> a lot of the changes are mechnical.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>
> Acked-by: Andrey Ignatov <rdna@...com>

...

> @@ -72,33 +70,21 @@ extern unsigned int sysctl_sched_autogroup_enabled;
>  extern int sysctl_sched_rr_timeslice;
>  extern int sched_rr_timeslice;
>  
> -extern int sched_rr_handler(struct ctl_table *table, int write,
> -		void __user *buffer, size_t *lenp,
> -		loff_t *ppos);
> -
> -extern int sched_rt_handler(struct ctl_table *table, int write,
> -		void __user *buffer, size_t *lenp,
> -		loff_t *ppos);
> -
> -#ifdef CONFIG_UCLAMP_TASK

Decided to skim through the patch one last time to double-check the fix
from previous iteration and found that this ifdef got lost below.

> -extern int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
> -				       void __user *buffer, size_t *lenp,
> -				       loff_t *ppos);
> -#endif
> -
> -extern int sysctl_numa_balancing(struct ctl_table *table, int write,
> -				 void __user *buffer, size_t *lenp,
> -				 loff_t *ppos);
> -
> -extern int sysctl_schedstats(struct ctl_table *table, int write,
> -				 void __user *buffer, size_t *lenp,
> -				 loff_t *ppos);
> +int sched_rr_handler(struct ctl_table *table, int write, void *buffer,
> +		size_t *lenp, loff_t *ppos);
> +int sched_rt_handler(struct ctl_table *table, int write, void *buffer,
> +		size_t *lenp, loff_t *ppos);
> +int sysctl_sched_uclamp_handler(struct ctl_table *table, int write,
> +		void *buffer, size_t *lenp, loff_t *ppos);

Here ^^

-- 
Andrey Ignatov