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[PATCH] selinux: fix and cleanup mprotect checks

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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>
This commit is contained in:
Stephen Smalley 2006-02-01 03:05:54 -08:00 committed by Linus Torvalds
parent ee13d785ea
commit db4c9641de
1 changed files with 21 additions and 29 deletions
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50
security/selinux/hooks.c
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@ -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;
}