[PATCH] selinux: fix and cleanup mprotect checks
Fix the SELinux mprotect checks on executable mappings so that they are not
re-applied when the mapping is already executable as well as cleaning up
the code. This avoids a situation where e.g. an application is prevented
from removing PROT_WRITE on an already executable mapping previously
authorized via execmem permission due to an execmod denial.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index b9f8d97..1bb5eea 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2454,35 +2454,27 @@
prot = reqprot;
#ifndef CONFIG_PPC32
- if ((prot & PROT_EXEC) && !(vma->vm_flags & VM_EXECUTABLE) &&
- (vma->vm_start >= vma->vm_mm->start_brk &&
- vma->vm_end <= vma->vm_mm->brk)) {
- /*
- * We are making an executable mapping in the brk region.
- * This has an additional execheap check.
- */
- rc = task_has_perm(current, current, PROCESS__EXECHEAP);
- if (rc)
- return rc;
- }
- if (vma->vm_file != NULL && vma->anon_vma != NULL && (prot & PROT_EXEC)) {
- /*
- * We are making executable a file mapping that has
- * had some COW done. Since pages might have been written,
- * check ability to execute the possibly modified content.
- * This typically should only occur for text relocations.
- */
- int rc = file_has_perm(current, vma->vm_file, FILE__EXECMOD);
- if (rc)
- return rc;
- }
- if (!vma->vm_file && (prot & PROT_EXEC) &&
- vma->vm_start <= vma->vm_mm->start_stack &&
- vma->vm_end >= vma->vm_mm->start_stack) {
- /* Attempt to make the process stack executable.
- * This has an additional execstack check.
- */
- rc = task_has_perm(current, current, PROCESS__EXECSTACK);
+ if ((prot & PROT_EXEC) && !(vma->vm_flags & VM_EXEC)) {
+ rc = 0;
+ if (vma->vm_start >= vma->vm_mm->start_brk &&
+ vma->vm_end <= vma->vm_mm->brk) {
+ rc = task_has_perm(current, current,
+ PROCESS__EXECHEAP);
+ } else if (!vma->vm_file &&
+ vma->vm_start <= vma->vm_mm->start_stack &&
+ vma->vm_end >= vma->vm_mm->start_stack) {
+ rc = task_has_perm(current, current, PROCESS__EXECSTACK);
+ } else if (vma->vm_file && vma->anon_vma) {
+ /*
+ * We are making executable a file mapping that has
+ * had some COW done. Since pages might have been
+ * written, check ability to execute the possibly
+ * modified content. This typically should only
+ * occur for text relocations.
+ */
+ rc = file_has_perm(current, vma->vm_file,
+ FILE__EXECMOD);
+ }
if (rc)
return rc;
}