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 <jeremy.linton@arm.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Mark Rutland <mark.rutland@arm.com>
[catalin.marinas@arm.com: added vm_struct vmlinux_rodata in map_kernel()]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
(cherry picked from commit 2f39b5f91eb4bccd786d194e70db1dccad784755)
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index e3f6cd740ea346bd887f01e2b46a558d8075d966..4c56e7a0621bcea078fb616487d60f9290f85214 100644 (file)
--- 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 9db46dfb6afb987c8ee59324fdc28d4e62f4ca61..75728047b60b33f29dea212e58b309db8424e119 100644 (file)
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -370,6 +370,7 @@ 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"
@@ -384,7 +385,8 @@ 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(VMEMMAP_START,

diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 41421c724fb9eb27a28ede211b0775af97b1fc32..e5348bbaa5d6bea2cc9158382e6aff5829e4ccad 100644 (file)
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -445,12 +445,18 @@ 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)
@@ -489,9 +495,10 @@ 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);