Commit db4c9641 authored by Stephen Smalley's avatar Stephen Smalley Committed by Linus Torvalds

[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: default avatarStephen Smalley <sds@tycho.nsa.gov>
Acked-by: default avatarJames Morris <jmorris@namei.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent ee13d785
......@@ -2454,35 +2454,27 @@ static int selinux_file_mprotect(struct vm_area_struct *vma,
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;
}
......
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