1 files changed, 27 insertions, 17 deletions

diff --git a/security/commoncap.c b/security/commoncap.c
index 01ab47845dcf..5aba82679a0b 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -25,20 +25,6 @@
 #include <linux/mount.h>
 #include <linux/sched.h>
 
-#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
-/*
- * Because of the reduced scope of CAP_SETPCAP when filesystem
- * capabilities are in effect, it is safe to allow this capability to
- * be available in the default configuration.
- */
-# define CAP_INIT_BSET  CAP_FULL_SET
-#else /* ie. ndef CONFIG_SECURITY_FILE_CAPABILITIES */
-# define CAP_INIT_BSET  CAP_INIT_EFF_SET
-#endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
-
-kernel_cap_t cap_bset = CAP_INIT_BSET;    /* systemwide capability bound */
-EXPORT_SYMBOL(cap_bset);
-
 /* Global security state */
 
 unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
@@ -140,6 +126,12 @@ int cap_capset_check (struct task_struct *target, kernel_cap_t *effective,
                 /* incapable of using this inheritable set */
                 return -EPERM;
         }
+        if (!cap_issubset(*inheritable,
+                           cap_combine(target->cap_inheritable,
+                                       current->cap_bset))) {
+                /* no new pI capabilities outside bounding set */
+                return -EPERM;
+        }
 
         /* verify restrictions on target's new Permitted set */
         if (!cap_issubset (*permitted,
@@ -337,10 +329,11 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
         /* Derived from fs/exec.c:compute_creds. */
         kernel_cap_t new_permitted, working;
 
-        new_permitted = cap_intersect (bprm->cap_permitted, cap_bset);
-        working = cap_intersect (bprm->cap_inheritable,
+        new_permitted = cap_intersect(bprm->cap_permitted,
+                                 current->cap_bset);
+        working = cap_intersect(bprm->cap_inheritable,
                                  current->cap_inheritable);
-        new_permitted = cap_combine (new_permitted, working);
+        new_permitted = cap_combine(new_permitted, working);
 
         if (bprm->e_uid != current->uid || bprm->e_gid != current->gid ||
             !cap_issubset (new_permitted, current->cap_permitted)) {
@@ -581,6 +574,23 @@ int cap_task_kill(struct task_struct *p, struct siginfo *info,
 
         return -EPERM;
 }
+
+/*
+ * called from kernel/sys.c for prctl(PR_CABSET_DROP)
+ * done without task_capability_lock() because it introduces
+ * no new races - i.e. only another task doing capget() on
+ * this task could get inconsistent info.  There can be no
+ * racing writer bc a task can only change its own caps.
+ */
+long cap_prctl_drop(unsigned long cap)
+{
+        if (!capable(CAP_SETPCAP))
+                return -EPERM;
+        if (!cap_valid(cap))
+                return -EINVAL;
+        cap_lower(current->cap_bset, cap);
+        return 0;
+}
 #else
 int cap_task_setscheduler (struct task_struct *p, int policy,
                            struct sched_param *lp)