From: Paolo 'Blaisorblade' Giarrusso <[email protected]>
Simplify the generic arch permission checking: the previous one was clumsy, as
it didn't account arch-specific implications (read implies exec, write implies
read, and so on).
Still to undo fixes for the archs (i386 and UML) which were modified for the
previous scheme.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <[email protected]>
---
linux-2.6.git-paolo/mm/memory.c | 49 ++++++++++++++++++++++++++--------------
1 files changed, 33 insertions(+), 16 deletions(-)
diff -puN mm/memory.c~rfp-sigsegv-4 mm/memory.c
--- linux-2.6.git/mm/memory.c~rfp-sigsegv-4 2005-08-12 17:18:55.000000000 +0200
+++ linux-2.6.git-paolo/mm/memory.c 2005-08-12 17:18:55.000000000 +0200
@@ -1923,6 +1923,35 @@ oom:
goto out;
}
+static inline int check_perms(struct vm_area_struct * vma, int access_mask) {
+ if (unlikely(vm_flags & VM_NONUNIFORM)) {
+ /* we used to check protections in arch handler, but with
+ * VM_NONUNIFORM the check is skipped. */
+#if 0
+ if ((access_mask & VM_WRITE) > (vm_flags & VM_WRITE))
+ goto err;
+ if ((access_mask & VM_READ) > (vm_flags & VM_READ))
+ goto err;
+ if ((access_mask & VM_EXEC) > (vm_flags & VM_EXEC))
+ goto err;
+#else
+ /* access_mask contains the type of the access, vm_flags are the
+ * declared protections, pte has the protection which will be
+ * given to the PTE's in that area. */
+ //pte_t pte = pfn_pte(0UL, protection_map[vm_flags & 0x0f|VM_SHARED]);
+ pte_t pte = pfn_pte(0UL, vma->vm_page_prot);
+ if ((access_mask & VM_WRITE) && ! pte_write(pte))
+ goto err;
+ if ((access_mask & VM_READ) && ! pte_read(pte))
+ goto err;
+ if ((access_mask & VM_EXEC) && ! pte_exec(pte))
+ goto err;
+#endif
+ }
+ return 0;
+err:
+ return -EPERM;
+}
/*
* Fault of a previously existing named mapping. Repopulate the pte
* from the encoded file_pte if possible. This enables swappable
@@ -1944,14 +1973,8 @@ static int do_file_page(struct mm_struct
((access_mask & VM_WRITE) && !(vma->vm_flags & VM_SHARED))) {
/* We're behaving as if pte_file was cleared, so check
* protections like in handle_pte_fault. */
- if (unlikely(vma->vm_flags & VM_NONUNIFORM)) {
- if ((access_mask & VM_WRITE) > (vma->vm_flags & VM_WRITE))
- goto out_segv;
- if ((access_mask & VM_READ) > (vma->vm_flags & VM_READ))
- goto out_segv;
- if ((access_mask & VM_EXEC) > (vma->vm_flags & VM_EXEC))
- goto out_segv;
- }
+ if (check_perms(vma, access_mask))
+ goto out_segv;
pte_clear(mm, address, pte);
return do_no_page(mm, vma, address, access_mask & VM_WRITE, pte, pmd);
@@ -2007,14 +2030,8 @@ static inline int handle_pte_fault(struc
/* when pte_file(), the VMA protections are useless. Otherwise,
* we used to check protections in arch handler, but with
* VM_NONUNIFORM the check is skipped. */
- if (unlikely(vma->vm_flags & VM_NONUNIFORM) && !pte_file(entry)) {
- if ((access_mask & VM_WRITE) > (vma->vm_flags & VM_WRITE))
- goto out_segv;
- if ((access_mask & VM_READ) > (vma->vm_flags & VM_READ))
- goto out_segv;
- if ((access_mask & VM_EXEC) > (vma->vm_flags & VM_EXEC))
- goto out_segv;
- }
+ if (!pte_file(entry) && check_perms(vma, access_mask))
+ goto out_segv;
/*
* If it truly wasn't present, we know that kswapd
_
-
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