Merge branch 'exec-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Pull execve fix from Eric Biederman:
 "While working on my exec cleanups I found a bug in exec that winds up
  miscomputing the ambient credentials during exec. Andy appears to have
  to been confused as to why credentials are computed for both the
  script and the interpreter

  From the original patch description:

   [3] Linux very confusingly processes both the script and the
       interpreter if applicable, for reasons that elude me. The results
       from thinking about a script's file capabilities and/or setuid
       bits are mostly discarded.

  The only value in struct cred that gets changed in cap_bprm_set_creds
  that I could find that might persist between the script and the
  interpreter was cap_ambient. Which is fixed with this trivial change"

* 'exec-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
  exec: Always set cap_ambient in cap_bprm_set_creds

Author: torvalds

security/commoncap.c

@@ -812,6 +812,7 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
 	int ret;
 	kuid_t root_uid;
 
+	new->cap_ambient = old->cap_ambient;
 	if (WARN_ON(!cap_ambient_invariant_ok(old)))
 		return -EPERM;