From ccd3988086364837d0c0fb4563d715c691636313 Mon Sep 17 00:00:00 2001 From: Prem Karat Date: Mon, 21 Apr 2014 09:33:16 +0530 Subject: [PATCH] MIPS: Enable VDSO randomization Based on commit 1091458d09e1a (mmap randomization) For 32-bit address spaces randomize within a 16MB space, for 64-bit within a 256MB space. Test Results: ------------ Without Patch (VDSO is not randomized) --------------------------------------- root@Maleo:~# ./aslr vdso FAIL: ASLR not functional (vdso always at 0x7fff7000) root@Maleo:~# ./aslr rekey vdso pre_val==cur_val value=0x7fff7000 With patch:(VDSO is randmoized and doesn't interfere with stack) ---------------------------------------------------------------- root@cavium-octeon2:~# ./aslr rekey vdso pre_val!=cur_val previous_value=0x7f830ea2 current_value=0x776e2000 root@cavium-octeon2:~# ./aslr rekey vdso pre_val!=cur_val previous_value=0x7fb0cea2 current_value=0x77209000 root@cavium-octeon2:~# ./aslr rekey vdso pre_val!=cur_val previous_value=0x7f985ea2 current_value=0x7770c000 root@cavium-octeon2:~# ./aslr rekey vdso pre_val!=cur_val previous_value=0x7fbc6ea2 current_value=0x7fe25000 Maps file output: ------------------------- root@cavium-octeon2:~# ./aslr rekey maps 78584000-785a5000 rwxp 00000000 00:00 0 [heap] 7f9d0000-7f9f1000 rw-p 00000000 00:00 0 [stack] 7ffa5000-7ffa6000 r-xp 00000000 00:00 0 [vdso] root@cavium-octeon2:~# ./aslr rekey maps 77de0000-77e01000 rwxp 00000000 00:00 0 [heap] 7f91b000-7f93c000 rw-p 00000000 00:00 0 [stack] 7ff99000-7ff9a000 r-xp 00000000 00:00 0 [vdso] root@cavium-octeon2:~# ./aslr rekey maps 77d7f000-77da0000 rwxp 00000000 00:00 0 [heap] 7fc2a000-7fc4b000 rw-p 00000000 00:00 0 [stack] 7fe09000-7fe0a000 r-xp 00000000 00:00 0 [vdso] root@cavium-octeon2:~# ./aslr rekey maps 7794c000-7794d000 r-xp 00000000 00:00 0 [vdso] 77e4b000-77e6c000 rwxp 00000000 00:00 0 [heap] 7f6e7000-7f708000 rw-p 00000000 00:00 0 [stack] root@cavium-octeon2:~# Signed-off-by: Prem Karat Cc: linux-mips@linux-mips.org Cc: sergei.shtylyov@cogentembedded.com Cc: ddaney.cavm@gmail.com Patchwork: https://patchwork.linux-mips.org/patch/6812 Signed-off-by: Ralf Baechle --- arch/mips/kernel/vdso.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/arch/mips/kernel/vdso.c b/arch/mips/kernel/vdso.c index 0f1af58b036a..ed2a278722a9 100644 --- a/arch/mips/kernel/vdso.c +++ b/arch/mips/kernel/vdso.c @@ -16,9 +16,11 @@ #include #include #include +#include #include #include +#include /* * Including would give use the 64-bit syscall numbers ... @@ -67,7 +69,18 @@ subsys_initcall(init_vdso); static unsigned long vdso_addr(unsigned long start) { - return STACK_TOP; + unsigned long offset = 0UL; + + if (current->flags & PF_RANDOMIZE) { + offset = get_random_int(); + offset <<= PAGE_SHIFT; + if (TASK_IS_32BIT_ADDR) + offset &= 0xfffffful; + else + offset &= 0xffffffful; + } + + return STACK_TOP + offset; } int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)