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MIPS: Randomize mmap if randomize_va_space is set 

Fairly straight forward: For 32-bit address spaces randomize within a
16MB space, for 64-bit within a 256MB space.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1480/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
David Daney 2010-07-19 13:14:56 -07:00 committed by Ralf Baechle
parent b3b3c176d9
commit 1091458d09
2 changed files with 31 additions and 1 deletions
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11
arch/mips/include/asm/processor.h
View File

@ -33,6 +33,11 @@ extern void (*cpu_wait)(void);
extern unsigned int vced_count, vcei_count;
/*
* MIPS does have an arch_pick_mmap_layout()
*/
#define HAVE_ARCH_PICK_MMAP_LAYOUT 1
/*
* A special page (the vdso) is mapped into all processes at the very
* top of the virtual memory space.
@ -52,6 +57,9 @@ extern unsigned int vced_count, vcei_count;
* space during mmap's.
*/
#define TASK_UNMAPPED_BASE ((TASK_SIZE / 3) & ~(PAGE_SIZE))
#define TASK_IS_32BIT_ADDR 1
#endif
#ifdef CONFIG_64BIT
@ -77,6 +85,9 @@ extern unsigned int vced_count, vcei_count;
PAGE_ALIGN(TASK_SIZE32 / 3) : PAGE_ALIGN(TASK_SIZE / 3))
#define TASK_SIZE_OF(tsk) \
(test_tsk_thread_flag(tsk, TIF_32BIT_ADDR) ? TASK_SIZE32 : TASK_SIZE)
#define TASK_IS_32BIT_ADDR test_thread_flag(TIF_32BIT_ADDR)
#endif
#ifdef __KERNEL__

21
arch/mips/kernel/syscall.c
View File

@ -29,6 +29,7 @@
#include <linux/ipc.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <asm/asm.h>
#include <asm/branch.h>
@ -116,7 +117,7 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
(!vmm || addr + len <= vmm->vm_start))
return addr;
}
addr = TASK_UNMAPPED_BASE;
addr = current->mm->mmap_base;
if (do_color_align)
addr = COLOUR_ALIGN(addr, pgoff);
else
@ -134,6 +135,24 @@ unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
}
}
void arch_pick_mmap_layout(struct mm_struct *mm)
{
unsigned long random_factor = 0UL;
if (current->flags & PF_RANDOMIZE) {
random_factor = get_random_int();
random_factor = random_factor << PAGE_SHIFT;
if (TASK_IS_32BIT_ADDR)
random_factor &= 0xfffffful;
else
random_factor &= 0xffffffful;
}
mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
mm->get_unmapped_area = arch_get_unmapped_area;
mm->unmap_area = arch_unmap_area;
}
SYSCALL_DEFINE6(mips_mmap, unsigned long, addr, unsigned long, len,
unsigned long, prot, unsigned long, flags, unsigned long,
fd, off_t, offset)