Revert "CRED: Fix regression in cap_capable() as shown up by sys_faccessat() [ver #2]"

This reverts commit 14eaddc967b16017d4a1a24d2be6c28ecbe06ed8.

David has a better version to come.

6 files changed, 23 insertions, 73 deletions

diff --git a/security/capability.c b/security/capability.c
index fd1493d..2dce66f 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -826,7 +826,6 @@ void security_fixup_ops(struct security_operations *ops)
 	set_to_cap_if_null(ops, capset);
 	set_to_cap_if_null(ops, acct);
 	set_to_cap_if_null(ops, capable);
-	set_to_cap_if_null(ops, task_capable);
 	set_to_cap_if_null(ops, quotactl);
 	set_to_cap_if_null(ops, quota_on);
 	set_to_cap_if_null(ops, sysctl);
diff --git a/security/commoncap.c b/security/commoncap.c
index 7f0b2a6..7971354 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -43,44 +43,28 @@ int cap_netlink_recv(struct sk_buff *skb, int cap)
 EXPORT_SYMBOL(cap_netlink_recv);
 
 /**
- * cap_capable - Determine whether current has a particular effective capability
+ * cap_capable - Determine whether a task has a particular effective capability
+ * @tsk: The task to query
  * @cap: The capability to check for
  * @audit: Whether to write an audit message or not
  *
  * Determine whether the nominated task has the specified capability amongst
- * its effective set, returning 0 if it does, -ve if it does not.  Note that
- * this uses current's subjective/effective credentials.
+ * its effective set, returning 0 if it does, -ve if it does not.
  *
  * NOTE WELL: cap_capable() cannot be used like the kernel's capable()
  * function.  That is, it has the reverse semantics: cap_capable() returns 0
  * when a task has a capability, but the kernel's capable() returns 1 for this
  * case.
  */
-int cap_capable(int cap, int audit)
+int cap_capable(struct task_struct *tsk, int cap, int audit)
 {
-	return cap_raised(current_cap(), cap) ? 0 : -EPERM;
-}
+	__u32 cap_raised;
 
-/**
- * cap_has_capability - Determine whether a task has a particular effective capability
- * @tsk: The task to query
- * @cred: The credentials to use
- * @cap: The capability to check for
- * @audit: Whether to write an audit message or not
- *
- * Determine whether the nominated task has the specified capability amongst
- * its effective set, returning 0 if it does, -ve if it does not.  Note that
- * this uses the task's objective/real credentials.
- *
- * NOTE WELL: cap_has_capability() cannot be used like the kernel's
- * has_capability() function.  That is, it has the reverse semantics:
- * cap_has_capability() returns 0 when a task has a capability, but the
- * kernel's has_capability() returns 1 for this case.
- */
-int cap_task_capable(struct task_struct *tsk, const struct cred *cred, int cap,
-		     int audit)
-{
-	return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
+	/* Derived from include/linux/sched.h:capable. */
+	rcu_read_lock();
+	cap_raised = cap_raised(__task_cred(tsk)->cap_effective, cap);
+	rcu_read_unlock();
+	return cap_raised ? 0 : -EPERM;
 }
 
 /**
@@ -176,7 +160,7 @@ static inline int cap_inh_is_capped(void)
 	/* they are so limited unless the current task has the CAP_SETPCAP
 	 * capability
 	 */
-	if (cap_capable(CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0)
+	if (cap_capable(current, CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0)
 		return 0;
 #endif
 	return 1;
@@ -885,7 +869,7 @@ int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
 		     & (new->securebits ^ arg2))			/*[1]*/
 		    || ((new->securebits & SECURE_ALL_LOCKS & ~arg2))	/*[2]*/
 		    || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS))	/*[3]*/
-		    || (cap_capable(CAP_SETPCAP, SECURITY_CAP_AUDIT) != 0) /*[4]*/
+		    || (cap_capable(current, CAP_SETPCAP, SECURITY_CAP_AUDIT) != 0) /*[4]*/
 			/*
 			 * [1] no changing of bits that are locked
 			 * [2] no unlocking of locks
@@ -966,7 +950,7 @@ int cap_vm_enough_memory(struct mm_struct *mm, long pages)
 {
 	int cap_sys_admin = 0;
 
-	if (cap_capable(CAP_SYS_ADMIN, SECURITY_CAP_NOAUDIT) == 0)
+	if (cap_capable(current, CAP_SYS_ADMIN, SECURITY_CAP_NOAUDIT) == 0)
 		cap_sys_admin = 1;
 	return __vm_enough_memory(mm, pages, cap_sys_admin);
 }
diff --git a/security/root_plug.c b/security/root_plug.c
index 559578f..40fb4f1 100644
--- a/security/root_plug.c
+++ b/security/root_plug.c
@@ -77,7 +77,6 @@ static struct security_operations rootplug_security_ops = {
 	.capget =			cap_capget,
 	.capset =			cap_capset,
 	.capable =			cap_capable,
-	.task_capable =			cap_task_capable,
 
 	.bprm_set_creds =		cap_bprm_set_creds,
 
diff --git a/security/security.c b/security/security.c
index 9bbc8e5..d85dbb3 100644
--- a/security/security.c
+++ b/security/security.c
@@ -154,31 +154,14 @@ int security_capset(struct cred *new, const struct cred *old,
 				    effective, inheritable, permitted);
 }
 
-int security_capable(int cap)
+int security_capable(struct task_struct *tsk, int cap)
 {
-	return security_ops->capable(cap, SECURITY_CAP_AUDIT);
+	return security_ops->capable(tsk, cap, SECURITY_CAP_AUDIT);
 }
 
-int security_task_capable(struct task_struct *tsk, int cap)
+int security_capable_noaudit(struct task_struct *tsk, int cap)
 {
-	const struct cred *cred;
-	int ret;
-
-	cred = get_task_cred(tsk);
-	ret = security_ops->task_capable(tsk, cred, cap, SECURITY_CAP_AUDIT);
-	put_cred(cred);
-	return ret;
-}
-
-int security_task_capable_noaudit(struct task_struct *tsk, int cap)
-{
-	const struct cred *cred;
-	int ret;
-
-	cred = get_task_cred(tsk);
-	ret = security_ops->task_capable(tsk, cred, cap, SECURITY_CAP_NOAUDIT);
-	put_cred(cred);
-	return ret;
+	return security_ops->capable(tsk, cap, SECURITY_CAP_NOAUDIT);
 }
 
 int security_acct(struct file *file)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index eb6c451..df30a75 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1433,13 +1433,12 @@ static int current_has_perm(const struct task_struct *tsk,
 
 /* Check whether a task is allowed to use a capability. */
 static int task_has_capability(struct task_struct *tsk,
-			       const struct cred *cred,
 			       int cap, int audit)
 {
 	struct avc_audit_data ad;
 	struct av_decision avd;
 	u16 sclass;
-	u32 sid = cred_sid(cred);
+	u32 sid = task_sid(tsk);
 	u32 av = CAP_TO_MASK(cap);
 	int rc;
 
@@ -1866,27 +1865,15 @@ static int selinux_capset(struct cred *new, const struct cred *old,
 	return cred_has_perm(old, new, PROCESS__SETCAP);
 }
 
-static int selinux_capable(int cap, int audit)
-{
-	int rc;
-
-	rc = secondary_ops->capable(cap, audit);
-	if (rc)
-		return rc;
-
-	return task_has_capability(current, current_cred(), cap, audit);
-}
-
-static int selinux_task_capable(struct task_struct *tsk,
-				const struct cred *cred, int cap, int audit)
+static int selinux_capable(struct task_struct *tsk, int cap, int audit)
 {
 	int rc;
 
-	rc = secondary_ops->task_capable(tsk, cred, cap, audit);
+	rc = secondary_ops->capable(tsk, cap, audit);
 	if (rc)
 		return rc;
 
-	return task_has_capability(tsk, cred, cap, audit);
+	return task_has_capability(tsk, cap, audit);
 }
 
 static int selinux_sysctl_get_sid(ctl_table *table, u16 tclass, u32 *sid)
@@ -2050,7 +2037,7 @@ static int selinux_vm_enough_memory(struct mm_struct *mm, long pages)
 {
 	int rc, cap_sys_admin = 0;
 
-	rc = selinux_capable(CAP_SYS_ADMIN, SECURITY_CAP_NOAUDIT);
+	rc = selinux_capable(current, CAP_SYS_ADMIN, SECURITY_CAP_NOAUDIT);
 	if (rc == 0)
 		cap_sys_admin = 1;
 
@@ -2893,7 +2880,7 @@ static int selinux_inode_getsecurity(const struct inode *inode, const char *name
 	 * and lack of permission just means that we fall back to the
 	 * in-core context value, not a denial.
 	 */
-	error = selinux_capable(CAP_MAC_ADMIN, SECURITY_CAP_NOAUDIT);
+	error = selinux_capable(current, CAP_MAC_ADMIN, SECURITY_CAP_NOAUDIT);
 	if (!error)
 		error = security_sid_to_context_force(isec->sid, &context,
 						      &size);
@@ -5581,7 +5568,6 @@ static struct security_operations selinux_ops = {
 	.capset =			selinux_capset,
 	.sysctl =			selinux_sysctl,
 	.capable =			selinux_capable,
-	.task_capable =			selinux_task_capable,
 	.quotactl =			selinux_quotactl,
 	.quota_on =			selinux_quota_on,
 	.syslog =			selinux_syslog,
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 7f12cc7..6bfaba6 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -2827,7 +2827,6 @@ struct security_operations smack_ops = {
 	.capget = 			cap_capget,
 	.capset = 			cap_capset,
 	.capable = 			cap_capable,
-	.task_capable = 		cap_task_capable,
 	.syslog = 			smack_syslog,
 	.settime = 			cap_settime,
 	.vm_enough_memory = 		cap_vm_enough_memory,