From 1091458d09e1a0788268578001f279250d2c0844 Mon Sep 17 00:00:00 2001 From: David Daney Date: Mon, 19 Jul 2010 13:14:56 -0700 Subject: [PATCH] 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 To: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/1480/ Signed-off-by: Ralf Baechle --- arch/mips/include/asm/processor.h | 11 +++++++++++ arch/mips/kernel/syscall.c | 21 ++++++++++++++++++++- 2 files changed, 31 insertions(+), 1 deletion(-) diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h index 5d33b727acf5..24d91f8618f0 100644 --- a/arch/mips/include/asm/processor.h +++ b/arch/mips/include/asm/processor.h @@ -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__ diff --git a/arch/mips/kernel/syscall.c b/arch/mips/kernel/syscall.c index dd81b0f87518..9824a829f61d 100644 --- a/arch/mips/kernel/syscall.c +++ b/arch/mips/kernel/syscall.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #include @@ -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) -- 2.20.1