From 2f39b5f91eb4bccd786d194e70db1dccad784755 Mon Sep 17 00:00:00 2001 From: Jeremy Linton Date: Fri, 19 Feb 2016 11:50:32 -0600 Subject: [PATCH] arm64: mm: Mark .rodata as RO Currently the .rodata section is actually still executable when DEBUG_RODATA is enabled. This changes that so the .rodata is actually read only, no execute. It also adds the .rodata section to the mem_init banner. Signed-off-by: Jeremy Linton Reviewed-by: Kees Cook Acked-by: Mark Rutland [catalin.marinas@arm.com: added vm_struct vmlinux_rodata in map_kernel()] Signed-off-by: Catalin Marinas --- arch/arm64/kernel/vmlinux.lds.S | 5 +++-- arch/arm64/mm/init.c | 4 +++- arch/arm64/mm/mmu.c | 19 +++++++++++++------ 3 files changed, 19 insertions(+), 9 deletions(-) diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index e3f6cd740ea3..4c56e7a0621b 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -114,8 +114,9 @@ SECTIONS *(.got) /* Global offset table */ } - RO_DATA(PAGE_SIZE) - EXCEPTION_TABLE(8) + ALIGN_DEBUG_RO_MIN(PAGE_SIZE) + RO_DATA(PAGE_SIZE) /* everything from this point to */ + EXCEPTION_TABLE(8) /* _etext will be marked RO NX */ NOTES ALIGN_DEBUG_RO_MIN(PAGE_SIZE) diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 80c8bdeeb41a..b938de23dc77 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -363,6 +363,7 @@ void __init mem_init(void) " vmalloc : 0x%16lx - 0x%16lx (%6ld GB)\n" " .init : 0x%p" " - 0x%p" " (%6ld KB)\n" " .text : 0x%p" " - 0x%p" " (%6ld KB)\n" + " .rodata : 0x%p" " - 0x%p" " (%6ld KB)\n" " .data : 0x%p" " - 0x%p" " (%6ld KB)\n" #ifdef CONFIG_SPARSEMEM_VMEMMAP " vmemmap : 0x%16lx - 0x%16lx (%6ld GB maximum)\n" @@ -377,7 +378,8 @@ void __init mem_init(void) MLM(MODULES_VADDR, MODULES_END), MLG(VMALLOC_START, VMALLOC_END), MLK_ROUNDUP(__init_begin, __init_end), - MLK_ROUNDUP(_text, _etext), + MLK_ROUNDUP(_text, __start_rodata), + MLK_ROUNDUP(__start_rodata, _etext), MLK_ROUNDUP(_sdata, _edata), #ifdef CONFIG_SPARSEMEM_VMEMMAP MLG((unsigned long)vmemmap, diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 00d166465ff4..d2d8b8c2e17f 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -449,12 +449,18 @@ static void __init map_mem(pgd_t *pgd) void mark_rodata_ro(void) { - if (!IS_ENABLED(CONFIG_DEBUG_RODATA)) - return; + unsigned long section_size; + section_size = (unsigned long)__start_rodata - (unsigned long)_stext; create_mapping_late(__pa(_stext), (unsigned long)_stext, - (unsigned long)_etext - (unsigned long)_stext, - PAGE_KERNEL_ROX); + section_size, PAGE_KERNEL_ROX); + /* + * mark .rodata as read only. Use _etext rather than __end_rodata to + * cover NOTES and EXCEPTION_TABLE. + */ + section_size = (unsigned long)_etext - (unsigned long)__start_rodata; + create_mapping_late(__pa(__start_rodata), (unsigned long)__start_rodata, + section_size, PAGE_KERNEL_RO); } void fixup_init(void) @@ -493,9 +499,10 @@ static void __init map_kernel_chunk(pgd_t *pgd, void *va_start, void *va_end, */ static void __init map_kernel(pgd_t *pgd) { - static struct vm_struct vmlinux_text, vmlinux_init, vmlinux_data; + static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_init, vmlinux_data; - map_kernel_chunk(pgd, _stext, _etext, PAGE_KERNEL_EXEC, &vmlinux_text); + map_kernel_chunk(pgd, _stext, __start_rodata, PAGE_KERNEL_EXEC, &vmlinux_text); + map_kernel_chunk(pgd, __start_rodata, _etext, PAGE_KERNEL, &vmlinux_rodata); map_kernel_chunk(pgd, __init_begin, __init_end, PAGE_KERNEL_EXEC, &vmlinux_init); map_kernel_chunk(pgd, _data, _end, PAGE_KERNEL, &vmlinux_data); -- 2.20.1