2006-08-23 19:06:43

by Kylene Jo Hall

Subject: [PATCH 1/7] mprotect patch for use by SLIM

This small patch makes mprotect available for use by SLIM for
write revocation.

Updated to allow the usage locking to work properly.

Signed-off-by: Mimi Zohar <[email protected]>
Signed-off-by: Kylene Hall <[email protected]>
---
include/linux/mm.h | 2 ++
mm/mprotect.c | 22 ++++++++++++++++------
2 files changed, 18 insertions(+), 6 deletions(-)

--- linux-2.6.18-rc3/mm/mprotect.c 2006-07-30 01:15:36.000000000 -0500
+++ linux-2.6.18-rc3-working/mm/mprotect.c 2006-08-07 13:11:07.000000000 -0500
@@ -19,6 +19,7 @@
#include <linux/mempolicy.h>
#include <linux/personality.h>
#include <linux/syscalls.h>
+#include <linux/module.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <asm/uaccess.h>
@@ -202,9 +203,10 @@ fail:
vm_unacct_memory(charged);
return error;
}
-
-asmlinkage long
-sys_mprotect(unsigned long start, size_t len, unsigned long prot)
+/*
+ * Call holding the current->mm->mmap_sem for writing
+ */
+int do_mprotect(unsigned long start, size_t len, unsigned long prot)
{
unsigned long vm_flags, nstart, end, tmp, reqprot;
struct vm_area_struct *vma, *prev;
@@ -234,8 +236,6 @@ sys_mprotect(unsigned long start, size_t

vm_flags = calc_vm_prot_bits(prot);

- down_write(&current->mm->mmap_sem);
-
vma = find_vma_prev(current->mm, start, &prev);
error = -ENOMEM;
if (!vma)
@@ -298,6 +298,16 @@ sys_mprotect(unsigned long start, size_t
}
}
out:
- up_write(&current->mm->mmap_sem);
return error;
}
+
+asmlinkage long
+sys_mprotect(unsigned long start, size_t len, unsigned long prot)
+{
+ int ret;
+
+ down_write(&current->mm->mmap_sem);
+ ret = do_mprotect(start, len, prot);
+ up_write(&current->mm->mmap_sem);
+ return ret;
+}
--- linux-2.6.18-rc3/include/linux/mm.h 2006-07-30 01:15:36.000000000 -0500
+++ linux-2.6.18-rc3-working/include/linux/mm.h 2006-08-01 12:18:13.000000000 -0500
@@ -137,6 +137,8 @@ extern unsigned int kobjsize(const void
#define VM_EXEC 0x00000004
#define VM_SHARED 0x00000008

+extern int do_mprotect(unsigned long start, size_t len, unsigned long prot);
+
/* mprotect() hardcodes VM_MAYREAD >> 4 == VM_READ, and so for r/w/x bits. */
#define VM_MAYREAD 0x00000010 /* limits for mprotect() etc */
#define VM_MAYWRITE 0x00000020