1 files changed, 65 insertions, 18 deletions

diff --git a/security/commoncap.c b/security/commoncap.c
index 64c2ed9c9015..f20e984ccfb4 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -27,6 +27,7 @@
 #include <linux/sched.h>
 #include <linux/prctl.h>
 #include <linux/securebits.h>
+#include <linux/user_namespace.h>
 
 /*
  * If a non-root user executes a setuid-root binary in
@@ -52,13 +53,12 @@ static void warn_setuid_and_fcaps_mixed(const char *fname)
 
 int cap_netlink_send(struct sock *sk, struct sk_buff *skb)
 {
-	NETLINK_CB(skb).eff_cap = current_cap();
 	return 0;
 }
 
 int cap_netlink_recv(struct sk_buff *skb, int cap)
 {
-	if (!cap_raised(NETLINK_CB(skb).eff_cap, cap))
+	if (!cap_raised(current_cap(), cap))
 		return -EPERM;
 	return 0;
 }
@@ -68,6 +68,7 @@ EXPORT_SYMBOL(cap_netlink_recv);
  * cap_capable - Determine whether a task has a particular effective capability
  * @tsk: The task to query
  * @cred: The credentials to use
+ * @ns:  The user namespace in which we need the capability
  * @cap: The capability to check for
  * @audit: Whether to write an audit message or not
  *
@@ -79,10 +80,30 @@ EXPORT_SYMBOL(cap_netlink_recv);
  * cap_has_capability() returns 0 when a task has a capability, but the
  * kernel's capable() and has_capability() returns 1 for this case.
  */
-int cap_capable(struct task_struct *tsk, const struct cred *cred, int cap,
-		int audit)
+int cap_capable(struct task_struct *tsk, const struct cred *cred,
+		struct user_namespace *targ_ns, int cap, int audit)
 {
-	return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
+	for (;;) {
+		/* The creator of the user namespace has all caps. */
+		if (targ_ns != &init_user_ns && targ_ns->creator == cred->user)
+			return 0;
+
+		/* Do we have the necessary capabilities? */
+		if (targ_ns == cred->user->user_ns)
+			return cap_raised(cred->cap_effective, cap) ? 0 : -EPERM;
+
+		/* Have we tried all of the parent namespaces? */
+		if (targ_ns == &init_user_ns)
+			return -EPERM;
+
+		/*
+		 *If you have a capability in a parent user ns, then you have
+		 * it over all children user namespaces as well.
+		 */
+		targ_ns = targ_ns->creator->user_ns;
+	}
+
+	/* We never get here */
 }
 
 /**
@@ -93,7 +114,7 @@ int cap_capable(struct task_struct *tsk, const struct cred *cred, int cap,
  * Determine whether the current process may set the system clock and timezone
  * information, returning 0 if permission granted, -ve if denied.
  */
-int cap_settime(struct timespec *ts, struct timezone *tz)
+int cap_settime(const struct timespec *ts, const struct timezone *tz)
 {
 	if (!capable(CAP_SYS_TIME))
 		return -EPERM;
@@ -106,18 +127,30 @@ int cap_settime(struct timespec *ts, struct timezone *tz)
  * @child: The process to be accessed
  * @mode: The mode of attachment.
  *
+ * If we are in the same or an ancestor user_ns and have all the target
+ * task's capabilities, then ptrace access is allowed.
+ * If we have the ptrace capability to the target user_ns, then ptrace
+ * access is allowed.
+ * Else denied.
+ *
  * Determine whether a process may access another, returning 0 if permission
  * granted, -ve if denied.
  */
 int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
 {
 	int ret = 0;
+	const struct cred *cred, *child_cred;
 
 	rcu_read_lock();
-	if (!cap_issubset(__task_cred(child)->cap_permitted,
-			  current_cred()->cap_permitted) &&
-	    !capable(CAP_SYS_PTRACE))
-		ret = -EPERM;
+	cred = current_cred();
+	child_cred = __task_cred(child);
+	if (cred->user->user_ns == child_cred->user->user_ns &&
+	    cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
+		goto out;
+	if (ns_capable(child_cred->user->user_ns, CAP_SYS_PTRACE))
+		goto out;
+	ret = -EPERM;
+out:
 	rcu_read_unlock();
 	return ret;
 }
@@ -126,18 +159,30 @@ int cap_ptrace_access_check(struct task_struct *child, unsigned int mode)
  * cap_ptrace_traceme - Determine whether another process may trace the current
  * @parent: The task proposed to be the tracer
  *
+ * If parent is in the same or an ancestor user_ns and has all current's
+ * capabilities, then ptrace access is allowed.
+ * If parent has the ptrace capability to current's user_ns, then ptrace
+ * access is allowed.
+ * Else denied.
+ *
  * Determine whether the nominated task is permitted to trace the current
  * process, returning 0 if permission is granted, -ve if denied.
  */
 int cap_ptrace_traceme(struct task_struct *parent)
 {
 	int ret = 0;
+	const struct cred *cred, *child_cred;
 
 	rcu_read_lock();
-	if (!cap_issubset(current_cred()->cap_permitted,
-			  __task_cred(parent)->cap_permitted) &&
-	    !has_capability(parent, CAP_SYS_PTRACE))
-		ret = -EPERM;
+	cred = __task_cred(parent);
+	child_cred = current_cred();
+	if (cred->user->user_ns == child_cred->user->user_ns &&
+	    cap_issubset(child_cred->cap_permitted, cred->cap_permitted))
+		goto out;
+	if (has_ns_capability(parent, child_cred->user->user_ns, CAP_SYS_PTRACE))
+		goto out;
+	ret = -EPERM;
+out:
 	rcu_read_unlock();
 	return ret;
 }
@@ -177,7 +222,8 @@ 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, current_cred(), CAP_SETPCAP,
+	if (cap_capable(current, current_cred(),
+			current_cred()->user->user_ns, CAP_SETPCAP,
 			SECURITY_CAP_AUDIT) == 0)
 		return 0;
 	return 1;
@@ -829,7 +875,8 @@ 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, current_cred(), CAP_SETPCAP,
+		    || (cap_capable(current, current_cred(),
+				    current_cred()->user->user_ns, CAP_SETPCAP,
 				    SECURITY_CAP_AUDIT) != 0)		/*[4]*/
 			/*
 			 * [1] no changing of bits that are locked
@@ -894,7 +941,7 @@ int cap_vm_enough_memory(struct mm_struct *mm, long pages)
 {
 	int cap_sys_admin = 0;
 
-	if (cap_capable(current, current_cred(), CAP_SYS_ADMIN,
+	if (cap_capable(current, current_cred(), &init_user_ns, CAP_SYS_ADMIN,
 			SECURITY_CAP_NOAUDIT) == 0)
 		cap_sys_admin = 1;
 	return __vm_enough_memory(mm, pages, cap_sys_admin);
@@ -921,7 +968,7 @@ int cap_file_mmap(struct file *file, unsigned long reqprot,
 	int ret = 0;
 
 	if (addr < dac_mmap_min_addr) {
-		ret = cap_capable(current, current_cred(), CAP_SYS_RAWIO,
+		ret = cap_capable(current, current_cred(), &init_user_ns, CAP_SYS_RAWIO,
 				  SECURITY_CAP_AUDIT);
 		/* set PF_SUPERPRIV if it turns out we allow the low mmap */
 		if (ret == 0)