Re: [PATCH 8/7 v21] LSM: Fixes for issues found in review

Stephen Smalley
2015-03-12T13:26:04Z

On 03/11/2015 06:42 PM, Casey Schaufler wrote:
> Subject: [PATCH 8/7 v21] LSM: Fixes for issues found in review
>
> Correct capability hook uses that hadn't been done properly in the 6/7 patch.
>
> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> Reported-by: Stephen Smalley <sds@tycho.nsa.gov>

Acked-by: Stephen Smalley <sds@tycho.nsa.gov>

>
> ---
>
> security/apparmor/domain.c | 8 +++-----
> security/selinux/hooks.c | 15 +--------------
> 2 files changed, 4 insertions(+), 19 deletions(-)
>
> diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
> index b09fff7..dc0027b 100644
> --- a/security/apparmor/domain.c
> +++ b/security/apparmor/domain.c
> @@ -529,15 +529,13 @@ cleanup:
> */
> int apparmor_bprm_secureexec(struct linux_binprm *bprm)
> {
> - int ret = cap_bprm_secureexec(bprm);
> -
> /* the decision to use secure exec is computed in set_creds
> * and stored in bprm->unsafe.
> */
> - if (!ret && (bprm->unsafe & AA_SECURE_X_NEEDED))
> - ret = 1;
> + if (bprm->unsafe & AA_SECURE_X_NEEDED)
> + return 1;

Not your fault but for the AA folks, I think this is a layering
violation; security modules shouldn't directly set bits in brpm->unsafe
as they could be used at any time by the core kernel; we have our own
bprm->security field for any module-private flags. If there was a
general need for such a flag, it should be defined with the rest of the
unsafe flags so that it is properly reserved.

>
> - return ret;
> + return 0;
> }
>
> /**
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index 3fd8610..e71c797 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -2008,7 +2008,7 @@ static int selinux_ptrace_traceme(struct task_struct *parent)
> static int selinux_capget(struct task_struct *target, kernel_cap_t *effective,
> kernel_cap_t *inheritable, kernel_cap_t *permitted)
> {
> - return cap_capget(target, effective, inheritable, permitted);
> + return current_has_perm(target, PROCESS__GETCAP);
> }
>
> static int selinux_capset(struct cred *new, const struct cred *old,
> @@ -2016,13 +2016,6 @@ static int selinux_capset(struct cred *new, const struct cred *old,
> const kernel_cap_t *inheritable,
> const kernel_cap_t *permitted)
> {
> - int error;
> -
> - error = cap_capset(new, old,
> - effective, inheritable, permitted);
> - if (error)
> - return error;
> -
> return cred_has_perm(old, new, PROCESS__SETCAP);
> }
>
> @@ -2039,12 +2032,6 @@ static int selinux_capset(struct cred *new, const struct cred *old,
> static int selinux_capable(const struct cred *cred, struct user_namespace *ns,
> int cap, int audit)
> {
> - int rc;
> -
> - rc = cap_capable(cred, ns, cap, audit);
> - if (rc)
> - return rc;
> -
> return cred_has_capability(cred, cap, audit);
> }
>
>