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;
 }