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Message-ID: <20110617153424.GA22220@albatros>
Date: Fri, 17 Jun 2011 19:34:24 +0400
From: Vasiliy Kulikov <segoon@...nwall.com>
To: linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org,
apparmor@...ts.ubuntu.com,
"selinux@...ho.nsa.gov Stephen Smalley" <sds@...ho.nsa.gov>,
James Morris <jmorris@...ei.org>,
Eric Paris <eparis@...isplace.org>,
John Johansen <john.johansen@...onical.com>,
kernel-hardening@...ts.openwall.com
Subject: Re: [RFC v1] security: introduce ptrace_task_access_check()
On Fri, Jun 17, 2011 at 19:29 +0400, Vasiliy Kulikov wrote:
> diff --git a/security/commoncap.c b/security/commoncap.c
> index a93b3b7..aa76791 100644
> --- a/security/commoncap.c
> +++ b/security/commoncap.c
> @@ -155,6 +155,26 @@ out:
> return ret;
> }
>
> +int cap_ptrace_task_access_check(struct task_struct *task, struct task_struct *child,
> + unsigned int mode)
> +{
> + int ret = 0;
> + const struct cred *cred, *child_cred;
> +
> + rcu_read_lock();
> + cred = __task_cred(task);
> + child_cred = __task_cred(child);
> + if (cred->user->user_ns == child_cred->user->user_ns &&
> + cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
> + goto out;
> + if (ns_task_capable(task, child_cred->user->user_ns, CAP_SYS_PTRACE))
> + goto out;
> + ret = -EPERM;
> +out:
> + rcu_read_unlock();
> + return ret;
> +}
> +
Actually cap_ptrace_access_check() may just call
cap_ptrace_task_access_check().
> /**
> * cap_ptrace_traceme - Determine whether another process may trace the current
> * @parent: The task proposed to be the tracer
> diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
> index 9637e10..f6582a7 100644
> --- a/security/smack/smack_access.c
> +++ b/security/smack/smack_access.c
> @@ -200,6 +200,49 @@ out_audit:
> return rc;
> }
>
> +int smk_taskacc(struct task_struct *task, char *obj_label, u32 mode, struct smk_audit_info *a)
> +{
> + struct task_smack *tsp = task_cred_xxx(task, security);
> + char *subject_label = smk_of_task(tsp);
> + int may;
> + int rc;
> +
> + /*
> + * Check the global rule list
> + */
> + rc = smk_access(subject_label, obj_label, mode, NULL);
> + if (rc == 0) {
> + /*
> + * If there is an entry in the task's rule list
> + * it can further restrict access.
> + */
> + may = smk_access_entry(subject_label, obj_label, &tsp->smk_rules);
> + if (may < 0)
> + goto out_audit;
> + if ((mode & may) == mode)
> + goto out_audit;
> + rc = -EACCES;
> + }
> +
> + /*
> + * Return if a specific label has been designated as the
> + * only one that gets privilege and current does not
> + * have that label.
> + */
> + if (smack_onlycap != NULL && smack_onlycap != subject_label)
> + goto out_audit;
> +
> + if (task_capable(task, CAP_MAC_OVERRIDE))
> + rc = 0;
> +
> +out_audit:
> +#ifdef CONFIG_AUDIT
> + if (a)
> + smack_log(subject_label, obj_label, mode, rc, a);
> +#endif
> + return rc;
> +}
> +
And smk_curacc() is a variant of smk_taskacc().
> /**
> * smk_curacc - determine if current has a specific access to an object
> * @obj_label: a pointer to the object's Smack label
--
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
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