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

[linux-2.6-block.git] / security / commoncap.c

diff --git a/security/commoncap.c b/security/commoncap.c
index 79713545cd631158fc4acd69dbfdcdd3c098e384..7f0b2a68717d6fd8d57837308dfe219848c8e30d 100644 (file)
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -43,28 +43,44 @@ int cap_netlink_recv(struct sk_buff *skb, int cap)
 EXPORT_SYMBOL(cap_netlink_recv);
 
 /**
- * cap_capable - Determine whether a task has a particular effective capability
- * @tsk: The task to query
+ * cap_capable - Determine whether current has a particular effective capability
  * @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.
+ * its effective set, returning 0 if it does, -ve if it does not.  Note that
+ * this uses current's subjective/effective credentials.
  *
  * 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(struct task_struct *tsk, int cap, int audit)
+int cap_capable(int cap, int audit)
 {
-       __u32 cap_raised;
+       return cap_raised(current_cap(), 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;
+/**
+ * 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;
 }
 
 /**
@@ -160,7 +176,7 @@ static inline int cap_inh_is_capped(void)
        /* they are so limited unless the current task has the CAP_SETPCAP
         * capability
         */
-       if (cap_capable(current, CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0)
+       if (cap_capable(CAP_SETPCAP, SECURITY_CAP_AUDIT) == 0)
                return 0;
 #endif
        return 1;
@@ -869,7 +885,7 @@ 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(current, CAP_SETPCAP, SECURITY_CAP_AUDIT) != 0) /*[4]*/
+                   || (cap_capable(CAP_SETPCAP, SECURITY_CAP_AUDIT) != 0) /*[4]*/
                        /*
                         * [1] no changing of bits that are locked
                         * [2] no unlocking of locks
@@ -950,7 +966,7 @@ int cap_vm_enough_memory(struct mm_struct *mm, long pages)
 {
        int cap_sys_admin = 0;
 
-       if (cap_capable(current, CAP_SYS_ADMIN, SECURITY_CAP_NOAUDIT) == 0)
+       if (cap_capable(CAP_SYS_ADMIN, SECURITY_CAP_NOAUDIT) == 0)
                cap_sys_admin = 1;
        return __vm_enough_memory(mm, pages, cap_sys_admin);
 }