Re: [PATCH v2 3/4] device_cgroup: Export devcgroup_check_permission

[Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>]

On Fri, May 17, 2019 at 04:15:06PM +0000, Kasiviswanathan, Harish wrote:
> For AMD compute (amdkfd) driver.
> 
> All AMD compute devices are exported via single device node /dev/kfd. As
> a result devices cannot be controlled individually using device cgroup.
> 
> AMD compute devices will rely on its graphics counterpart that exposes
> /dev/dri/renderN node for each device. For each task (based on its
> cgroup), KFD driver will check if /dev/dri/renderN node is accessible
> before exposing it.
> 
> Change-Id: I1b9705b2c30622a27655f4f878980fa138dbf373
> Signed-off-by: Harish Kasiviswanathan <Harish.Kasiviswanathan@amd.com>
> ---
>  include/linux/device_cgroup.h | 19 ++++---------------
>  security/device_cgroup.c      | 15 +++++++++++++--
>  2 files changed, 17 insertions(+), 17 deletions(-)
> 
> diff --git a/include/linux/device_cgroup.h b/include/linux/device_cgroup.h
> index 8557efe096dc..bd19897bd582 100644
> --- a/include/linux/device_cgroup.h
> +++ b/include/linux/device_cgroup.h
> @@ -12,26 +12,15 @@
>  #define DEVCG_DEV_ALL   4  /* this represents all devices */
>  
>  #ifdef CONFIG_CGROUP_DEVICE
> -extern int __devcgroup_check_permission(short type, u32 major, u32 minor,
> -					short access);
> +extern int devcgroup_check_permission(short type, u32 major, u32 minor,
> +				      short access);
>  #else
> -static inline int __devcgroup_check_permission(short type, u32 major, u32 minor,
> -					       short access)
> +static inline int devcgroup_check_permission(short type, u32 major, u32 minor,
> +					     short access)
>  { return 0; }
>  #endif
>  
>  #if defined(CONFIG_CGROUP_DEVICE) || defined(CONFIG_CGROUP_BPF)
> -static inline int devcgroup_check_permission(short type, u32 major, u32 minor,
> -					     short access)
> -{
> -	int rc = BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type, major, minor, access);
> -
> -	if (rc)
> -		return -EPERM;
> -
> -	return __devcgroup_check_permission(type, major, minor, access);
> -}
> -
>  static inline int devcgroup_inode_permission(struct inode *inode, int mask)
>  {
>  	short type, access = 0;
> diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> index cd97929fac66..3c57e05bf73b 100644
> --- a/security/device_cgroup.c
> +++ b/security/device_cgroup.c
> @@ -801,8 +801,8 @@ struct cgroup_subsys devices_cgrp_subsys = {
>   *
>   * returns 0 on success, -EPERM case the operation is not permitted
>   */
> -int __devcgroup_check_permission(short type, u32 major, u32 minor,
> -				 short access)
> +static int __devcgroup_check_permission(short type, u32 major, u32 minor,
> +					short access)
>  {
>  	struct dev_cgroup *dev_cgroup;
>  	bool rc;
> @@ -824,3 +824,14 @@ int __devcgroup_check_permission(short type, u32 major, u32 minor,
>  
>  	return 0;
>  }
> +
> +int devcgroup_check_permission(short type, u32 major, u32 minor, short access)
> +{
> +	int rc = BPF_CGROUP_RUN_PROG_DEVICE_CGROUP(type, major, minor, access);
> +
> +	if (rc)
> +		return -EPERM;
> +
> +	return __devcgroup_check_permission(type, major, minor, access);
> +}
> +EXPORT_SYMBOL(devcgroup_check_permission);

Perfect, now looks good to me!

Please, feel free to use my acks for patches 3 and 4:
Acked-by: Roman Gushchin <guro@fb.com>

Thanks!
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