1 files changed, 94 insertions, 9 deletions

diff --git a/security/commoncap.c b/security/commoncap.c
index 852905789caf..e8c3f5e46705 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -24,11 +24,8 @@
 #include <linux/hugetlb.h>
 #include <linux/mount.h>
 #include <linux/sched.h>
-
-/* Global security state */
-
-unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */
-EXPORT_SYMBOL(securebits);
+#include <linux/prctl.h>
+#include <linux/securebits.h>
 
 int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
 {
@@ -368,7 +365,7 @@ void cap_bprm_apply_creds (struct linux_binprm *bprm, int unsafe)
 
         /* AUD: Audit candidate if current->cap_effective is set */
 
-        current->keep_capabilities = 0;
+        current->securebits &= ~issecure_mask(SECURE_KEEP_CAPS);
 }
 
 int cap_bprm_secureexec (struct linux_binprm *bprm)
@@ -448,7 +445,7 @@ static inline void cap_emulate_setxuid (int old_ruid, int old_euid,
 {
         if ((old_ruid == 0 || old_euid == 0 || old_suid == 0) &&
             (current->uid != 0 && current->euid != 0 && current->suid != 0) &&
-            !current->keep_capabilities) {
+            !issecure(SECURE_KEEP_CAPS)) {
                 cap_clear (current->cap_permitted);
                 cap_clear (current->cap_effective);
         }
@@ -547,7 +544,7 @@ int cap_task_setnice (struct task_struct *p, int nice)
  * 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)
+static long cap_prctl_drop(unsigned long cap)
 {
         if (!capable(CAP_SETPCAP))
                 return -EPERM;
@@ -556,6 +553,7 @@ long cap_prctl_drop(unsigned long cap)
         cap_lower(current->cap_bset, cap);
         return 0;
 }
+
 #else
 int cap_task_setscheduler (struct task_struct *p, int policy,
                            struct sched_param *lp)
@@ -572,12 +570,99 @@ int cap_task_setnice (struct task_struct *p, int nice)
 }
 #endif
 
+int cap_task_prctl(int option, unsigned long arg2, unsigned long arg3,
+                   unsigned long arg4, unsigned long arg5, long *rc_p)
+{
+        long error = 0;
+
+        switch (option) {
+        case PR_CAPBSET_READ:
+                if (!cap_valid(arg2))
+                        error = -EINVAL;
+                else
+                        error = !!cap_raised(current->cap_bset, arg2);
+                break;
+#ifdef CONFIG_SECURITY_FILE_CAPABILITIES
+        case PR_CAPBSET_DROP:
+                error = cap_prctl_drop(arg2);
+                break;
+
+        /*
+         * The next four prctl's remain to assist with transitioning a
+         * system from legacy UID=0 based privilege (when filesystem
+         * capabilities are not in use) to a system using filesystem
+         * capabilities only - as the POSIX.1e draft intended.
+         *
+         * Note:
+         *
+         *  PR_SET_SECUREBITS =
+         *      issecure_mask(SECURE_KEEP_CAPS_LOCKED)
+         *    | issecure_mask(SECURE_NOROOT)
+         *    | issecure_mask(SECURE_NOROOT_LOCKED)
+         *    | issecure_mask(SECURE_NO_SETUID_FIXUP)
+         *    | issecure_mask(SECURE_NO_SETUID_FIXUP_LOCKED)
+         *
+         * will ensure that the current process and all of its
+         * children will be locked into a pure
+         * capability-based-privilege environment.
+         */
+        case PR_SET_SECUREBITS:
+                if ((((current->securebits & SECURE_ALL_LOCKS) >> 1)
+                     & (current->securebits ^ arg2))                  /*[1]*/
+                    || ((current->securebits & SECURE_ALL_LOCKS
+                         & ~arg2))                                    /*[2]*/
+                    || (arg2 & ~(SECURE_ALL_LOCKS | SECURE_ALL_BITS)) /*[3]*/
+                    || (cap_capable(current, CAP_SETPCAP) != 0)) {    /*[4]*/
+                        /*
+                         * [1] no changing of bits that are locked
+                         * [2] no unlocking of locks
+                         * [3] no setting of unsupported bits
+                         * [4] doing anything requires privilege (go read about
+                         *     the "sendmail capabilities bug")
+                         */
+                        error = -EPERM;  /* cannot change a locked bit */
+                } else {
+                        current->securebits = arg2;
+                }
+                break;
+        case PR_GET_SECUREBITS:
+                error = current->securebits;
+                break;
+
+#endif /* def CONFIG_SECURITY_FILE_CAPABILITIES */
+
+        case PR_GET_KEEPCAPS:
+                if (issecure(SECURE_KEEP_CAPS))
+                        error = 1;
+                break;
+        case PR_SET_KEEPCAPS:
+                if (arg2 > 1) /* Note, we rely on arg2 being unsigned here */
+                        error = -EINVAL;
+                else if (issecure(SECURE_KEEP_CAPS_LOCKED))
+                        error = -EPERM;
+                else if (arg2)
+                        current->securebits |= issecure_mask(SECURE_KEEP_CAPS);
+                else
+                        current->securebits &=
+                                ~issecure_mask(SECURE_KEEP_CAPS);
+                break;
+
+        default:
+                /* No functionality available - continue with default */
+                return 0;
+        }
+
+        /* Functionality provided */
+        *rc_p = error;
+        return 1;
+}
+
 void cap_task_reparent_to_init (struct task_struct *p)
 {
         cap_set_init_eff(p->cap_effective);
         cap_clear(p->cap_inheritable);
         cap_set_full(p->cap_permitted);
-        p->keep_capabilities = 0;
+        p->securebits = SECUREBITS_DEFAULT;
         return;
 }