Re: [RFC PATCH v2 9/9] Smack: Brutalist io_uring support with debug

Paul Moore
2021-08-31T14:45:21Z

On Wed, Aug 11, 2021 at 4:49 PM Paul Moore <paul@paul-moore.com> wrote:
>
> From: Casey Schaufler <casey@schaufler-ca.com>
>
> Add Smack privilege checks for io_uring. Use CAP_MAC_OVERRIDE
> for the override_creds case and CAP_MAC_ADMIN for creating a
> polling thread. These choices are based on conjecture regarding
> the intent of the surrounding code.
>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> [PM: make the smack_uring_* funcs static]
> Signed-off-by: Paul Moore <paul@paul-moore.com>
>
> ---
> v2:
> - made the smack_uring_* funcs static
> v1:
> - initial draft
> ---
> security/smack/smack_lsm.c | 64 ++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 64 insertions(+)
>
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 223a6da0e6dc..7fb094098f38 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -4691,6 +4691,66 @@ static int smack_dentry_create_files_as(struct dentry *dentry, int mode,
> return 0;
> }
>
> +#ifdef CONFIG_IO_URING
> +/**
> + * smack_uring_override_creds - Is io_uring cred override allowed?
> + * @new: the target creds
> + *
> + * Check to see if the current task is allowed to override it's credentials
> + * to service an io_uring operation.
> + */
> +static int smack_uring_override_creds(const struct cred *new)
> +{
> + struct task_smack *tsp = smack_cred(current_cred());
> + struct task_smack *nsp = smack_cred(new);
> +
> +#if 1
> + if (tsp->smk_task == nsp->smk_task)
> + pr_info("%s: Smack matches %s\n", __func__,
> + tsp->smk_task->smk_known);
> + else
> + pr_info("%s: Smack override check %s to %s\n", __func__,
> + tsp->smk_task->smk_known, nsp->smk_task->smk_known);
> +#endif

Casey, with the idea of posting a v3 towards the end of the merge
window next week, without the RFC tag and with the intention of
merging it into -next during the first/second week of the -rcX phase,
do you have any objections to me removing the debug code (#if 1 ...
#endif) from your patch? Did you have any other changes?

--
paul moore