[PATCH v3 8/8] Smack: Brutalist io_uring support with debug

[Casey Schaufler]

On 9/13/2021 8:33 PM, Paul Moore wrote:
> From: Casey Schaufler <casey at 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 at schaufler-ca.com>
> [PM: make the smack_uring_* funcs static, remove debug code]
> Signed-off-by: Paul Moore <paul at paul-moore.com>

You want to change the subject:

	[PATCH v3 8/8] Smack: Brutalist io_uring support with debug

	s/ with debug//

>
> ---
> v3:
> - removed debug code
> v2:
> - made the smack_uring_* funcs static
> v1:
> - initial draft
> ---
>  security/smack/smack_lsm.c |   46 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 46 insertions(+)
>
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index cacbe7518519..f90ab1efeb6d 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -4691,6 +4691,48 @@ 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);
> +
> +	/*
> +	 * Allow the degenerate case where the new Smack value is
> +	 * the same as the current Smack value.
> +	 */
> +	if (tsp->smk_task == nsp->smk_task)
> +		return 0;
> +
> +	if (smack_privileged_cred(CAP_MAC_OVERRIDE, current_cred()))
> +		return 0;
> +
> +	return -EPERM;
> +}
> +
> +/**
> + * smack_uring_sqpoll - check if a io_uring polling thread can be created
> + *
> + * Check to see if the current task is allowed to create a new io_uring
> + * kernel polling thread.
> + */
> +static int smack_uring_sqpoll(void)
> +{
> +	if (smack_privileged_cred(CAP_MAC_ADMIN, current_cred()))
> +		return 0;
> +
> +	return -EPERM;
> +}
> +
> +#endif /* CONFIG_IO_URING */
> +
>  struct lsm_blob_sizes smack_blob_sizes __lsm_ro_after_init = {
>  	.lbs_cred = sizeof(struct task_smack),
>  	.lbs_file = sizeof(struct smack_known *),
> @@ -4843,6 +4885,10 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
>  	LSM_HOOK_INIT(inode_copy_up, smack_inode_copy_up),
>  	LSM_HOOK_INIT(inode_copy_up_xattr, smack_inode_copy_up_xattr),
>  	LSM_HOOK_INIT(dentry_create_files_as, smack_dentry_create_files_as),
> +#ifdef CONFIG_IO_URING
> +	LSM_HOOK_INIT(uring_override_creds, smack_uring_override_creds),
> +	LSM_HOOK_INIT(uring_sqpoll, smack_uring_sqpoll),
> +#endif
>  };
>  
>  
>
> --
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