[RESEND,RFC,1/3] lsm: Clarify documentation of vm_enough_memory hook

Message ID 20221028165423.386151-1-roberto.sassu@huaweicloud.com
State New
Headers
Series [RESEND,RFC,1/3] lsm: Clarify documentation of vm_enough_memory hook |

Commit Message

Roberto Sassu Oct. 28, 2022, 4:54 p.m. UTC
  From: Roberto Sassu <roberto.sassu@huawei.com>

include/linux/lsm_hooks.h reports the result of the LSM infrastructure to
the callers, not what LSMs should return to the LSM infrastructure.

Clarify that and add that returning 1 from the LSMs means calling
__vm_enough_memory() with cap_sys_admin set, 0 without.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
 include/linux/lsm_hooks.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
  

Comments

KP Singh Nov. 3, 2022, 3:11 p.m. UTC | #1
On Fri, Oct 28, 2022 at 6:55 PM Roberto Sassu
<roberto.sassu@huaweicloud.com> wrote:
>
> From: Roberto Sassu <roberto.sassu@huawei.com>
>
> include/linux/lsm_hooks.h reports the result of the LSM infrastructure to
> the callers, not what LSMs should return to the LSM infrastructure.
>
> Clarify that and add that returning 1 from the LSMs means calling
> __vm_enough_memory() with cap_sys_admin set, 0 without.
>
> Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>

Reviewed-by: KP Singh <kpsingh@kernel.org>

> ---
>  include/linux/lsm_hooks.h | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index 4ec80b96c22e..f40b82ca91e7 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -1411,7 +1411,9 @@
>   *     Check permissions for allocating a new virtual mapping.
>   *     @mm contains the mm struct it is being added to.
>   *     @pages contains the number of pages.
> - *     Return 0 if permission is granted.
> + *     Return 0 if permission is granted by LSMs to the caller. LSMs should
> + *     return 1 if __vm_enough_memory() should be called with
> + *     cap_sys_admin set, 0 if not.
>   *
>   * @ismaclabel:
>   *     Check if the extended attribute specified by @name
> --
> 2.25.1
>
  

Patch

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 4ec80b96c22e..f40b82ca91e7 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1411,7 +1411,9 @@ 
  *	Check permissions for allocating a new virtual mapping.
  *	@mm contains the mm struct it is being added to.
  *	@pages contains the number of pages.
- *	Return 0 if permission is granted.
+ *	Return 0 if permission is granted by LSMs to the caller. LSMs should
+ *	return 1 if __vm_enough_memory() should be called with
+ *	cap_sys_admin set, 0 if not.
  *
  * @ismaclabel:
  *	Check if the extended attribute specified by @name