[v4,2/4] bpf-lsm: Make bpf_lsm_userns_create() sleepable

Commit Message

Frederick Lawler Aug. 1, 2022, 6:01 p.m. UTC

Users may want to audit calls to security_create_user_ns() and access
user space memory. Also create_user_ns() runs without
pagefault_disabled(). Therefore, make bpf_lsm_userns_create() sleepable
for mandatory access control policies.

Signed-off-by: Frederick Lawler <[e-mail]>
Acked-by: Christian Brauner (Microsoft) <[e-mail]>

---
Changes since v3:
- None
Changes since v2:
- Rename create_user_ns hook to userns_create
Changes since v1:
- None
---
 kernel/bpf/bpf_lsm.c | 1 +
 1 file changed, 1 insertion(+)

Comments

Alexei Starovoitov Aug. 1, 2022, 11 p.m. UTC | #1

On Mon, Aug 01, 2022 at 01:01:44PM -0500, Frederick Lawler wrote:
> Users may want to audit calls to security_create_user_ns() and access
> user space memory. Also create_user_ns() runs without
> pagefault_disabled(). Therefore, make bpf_lsm_userns_create() sleepable
> for mandatory access control policies.
> 
> Signed-off-by: Frederick Lawler <[e-mail]>
> Acked-by: Christian Brauner (Microsoft) <[e-mail]>

We can take this set through bpf-next tree if it's easier.

Or if it goes through other trees:
Acked-by: Alexei Starovoitov <[e-mail]>

Paul Moore Aug. 1, 2022, 11:06 p.m. UTC | #2

On Mon, Aug 1, 2022 at 7:00 PM Alexei Starovoitov
<[e-mail]> wrote:
>
> On Mon, Aug 01, 2022 at 01:01:44PM -0500, Frederick Lawler wrote:
> > Users may want to audit calls to security_create_user_ns() and access
> > user space memory. Also create_user_ns() runs without
> > pagefault_disabled(). Therefore, make bpf_lsm_userns_create() sleepable
> > for mandatory access control policies.
> >
> > Signed-off-by: Frederick Lawler <[e-mail]>
> > Acked-by: Christian Brauner (Microsoft) <[e-mail]>
>
> We can take this set through bpf-next tree if it's easier.

Thanks Alexei, but I'm currently planning to merge it into the LSM
next branch once the merge window closes.

> Or if it goes through other trees:
> Acked-by: Alexei Starovoitov <[e-mail]>

I appreciate the review/ACK, would you mind reviewing the tests too (patch 3/4)?

KP Singh Aug. 2, 2022, 9:29 p.m. UTC | #3

On Mon, Aug 1, 2022 at 8:02 PM Frederick Lawler <[e-mail]> wrote:
>
> Users may want to audit calls to security_create_user_ns() and access
> user space memory. Also create_user_ns() runs without
> pagefault_disabled(). Therefore, make bpf_lsm_userns_create() sleepable
> for mandatory access control policies.
>
> Signed-off-by: Frederick Lawler <[e-mail]>
> Acked-by: Christian Brauner (Microsoft) <[e-mail]>

Acked-by: KP Singh <[e-mail]>

Patch

diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c
index c1351df9f7ee..4593437809cc 100644
--- a/kernel/bpf/bpf_lsm.c
+++ b/kernel/bpf/bpf_lsm.c
@@ -250,6 +250,7 @@  BTF_ID(func, bpf_lsm_task_getsecid_obj)
 BTF_ID(func, bpf_lsm_task_prctl)
 BTF_ID(func, bpf_lsm_task_setscheduler)
 BTF_ID(func, bpf_lsm_task_to_inode)
+BTF_ID(func, bpf_lsm_userns_create)
 BTF_SET_END(sleepable_lsm_hooks)
 
 bool bpf_lsm_is_sleepable_hook(u32 btf_id)