diff options
| author | David Daney <ddaney@caviumnetworks.com> | 2010-07-19 13:14:56 -0700 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2010-08-05 13:26:05 +0100 |
| commit | 1091458d09e1a0788268578001f279250d2c0844 (patch) | |
| tree | 9a02e6153d6658cab4b653ba845e68b161cac908 | |
| parent | b3b3c176d9150af542d9ba5e5b292d233883ff85 (diff) | |
| download | lwn-1091458d09e1a0788268578001f279250d2c0844.tar.gz lwn-1091458d09e1a0788268578001f279250d2c0844.zip | |
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>
| -rw-r--r-- | arch/mips/include/asm/processor.h | 11 | ||||
| -rw-r--r-- | arch/mips/kernel/syscall.c | 21 |
2 files changed, 31 insertions, 1 deletions
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 @@ -34,6 +34,11 @@ 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 <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) |