From: Stephen Smalley <sds@tycho.nsa.gov>
Date: Fri, 8 Apr 2016 17:55:03 +0000 (-0400)
Subject: selinux: apply execstack check on thread stacks
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=c2316dbf124257ae19fd2e29cb5ec51060649d38;p=linux-beck.git

selinux: apply execstack check on thread stacks

The execstack check was only being applied on the main
process stack.  Thread stacks allocated via mmap were
only subject to the execmem permission check.  Augment
the check to apply to the current thread stack as well.
Note that this does NOT prevent making a different thread's
stack executable.

Suggested-by: Nick Kralevich <nnk@google.com>
Acked-by: Nick Kralevich <nnk@google.com>
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
---

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index bbff80c6d3f2..a00ab81ab719 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3479,8 +3479,9 @@ static int selinux_file_mprotect(struct vm_area_struct *vma,
 		    vma->vm_end <= vma->vm_mm->brk) {
 			rc = cred_has_perm(cred, cred, PROCESS__EXECHEAP);
 		} else if (!vma->vm_file &&
-			   vma->vm_start <= vma->vm_mm->start_stack &&
-			   vma->vm_end >= vma->vm_mm->start_stack) {
+			   ((vma->vm_start <= vma->vm_mm->start_stack &&
+			     vma->vm_end >= vma->vm_mm->start_stack) ||
+			    vma_is_stack_for_task(vma, current))) {
 			rc = current_has_perm(current, PROCESS__EXECSTACK);
 		} else if (vma->vm_file && vma->anon_vma) {
 			/*