Re: [RFC][PATCH 1/4] lsm: Clarify documentation of vm_enough_memory hook
From: Paul Moore <paul@paul-moore.com>
Date: 2022-11-16 19:28:50
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On Wed, Nov 16, 2022 at 2:18 PM KP Singh [off-list ref] wrote:
On Wed, Nov 16, 2022 at 9:06 AM Roberto Sassu [off-list ref] wrote:quoted
On Tue, 2022-11-15 at 21:11 -0500, Paul Moore wrote:quoted
On Tue, Nov 15, 2022 at 12:57 PM Roberto Sassu [off-list ref] wrote:quoted
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.I think this is a nice addition, but according to the code, any value greater than zero will trigger the caller-should-have-CAP_SYS_ADMIN behavior, not just 1. I suggest updating the comment.Ok, yes. Thanks.Also, this is an unrelated patch and you can probably send it independently, especially since the other changes will now land mostly via BPF.
Yes, the doc/comment changes really have nothing to do with the other stuff we are discussing in this patchset. -- paul-moore.com