Merge branch 'mm-readonly-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull read-only kernel memory updates from Ingo Molnar:
 "This tree adds two (security related) enhancements to the kernel's
  handling of read-only kernel memory:

   - extend read-only kernel memory to a new class of formerly writable
     kernel data: 'post-init read-only memory' via the __ro_after_init
     attribute, and mark the ARM and x86 vDSO as such read-only memory.

     This kind of attribute can be used for data that requires a once
     per bootup initialization sequence, but is otherwise never modified
     after that point.

     This feature was based on the work by PaX Team and Brad Spengler.

     (by Kees Cook, the ARM vDSO bits by David Brown.)

   - make CONFIG_DEBUG_RODATA always enabled on x86 and remove the
     Kconfig option.  This simplifies the kernel and also signals that
     read-only memory is the default model and a first-class citizen.
     (Kees Cook)"

* 'mm-readonly-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  ARM/vdso: Mark the vDSO code read-only after init
  x86/vdso: Mark the vDSO code read-only after init
  lkdtm: Verify that '__ro_after_init' works correctly
  arch: Introduce post-init read-only memory
  x86/mm: Always enable CONFIG_DEBUG_RODATA and remove the Kconfig option
  mm/init: Add 'rodata=off' boot cmdline parameter to disable read-only kernel mappings
  asm-generic: Consolidate mark_rodata_ro()

19 files changed, 30 insertions, 74 deletions

diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h
index d5525bfc7e3e..9156fc303afd 100644
--- a/arch/arm/include/asm/cacheflush.h
+++ b/arch/arm/include/asm/cacheflush.h
@@ -491,7 +491,6 @@ static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
 #endif
 
 #ifdef CONFIG_DEBUG_RODATA
-void mark_rodata_ro(void);
 void set_kernel_text_rw(void);
 void set_kernel_text_ro(void);
 #else
diff --git a/arch/arm/vdso/vdso.S b/arch/arm/vdso/vdso.S
index b2b97e3e7bab..a62a7b64f49c 100644
--- a/arch/arm/vdso/vdso.S
+++ b/arch/arm/vdso/vdso.S
@@ -23,9 +23,8 @@
 #include <linux/const.h>
 #include <asm/page.h>
 
-	__PAGE_ALIGNED_DATA
-
 	.globl vdso_start, vdso_end
+	.section .data..ro_after_init
 	.balign PAGE_SIZE
 vdso_start:
 	.incbin "arch/arm/vdso/vdso.so"
diff --git a/arch/arm64/include/asm/cacheflush.h b/arch/arm64/include/asm/cacheflush.h
index 7fc294c3bc5b..22dda613f9c9 100644
--- a/arch/arm64/include/asm/cacheflush.h
+++ b/arch/arm64/include/asm/cacheflush.h
@@ -156,8 +156,4 @@ int set_memory_rw(unsigned long addr, int numpages);
 int set_memory_x(unsigned long addr, int numpages);
 int set_memory_nx(unsigned long addr, int numpages);
 
-#ifdef CONFIG_DEBUG_RODATA
-void mark_rodata_ro(void);
-#endif
-
 #endif
diff --git a/arch/parisc/include/asm/cache.h b/arch/parisc/include/asm/cache.h
index 3d0e17bcc8e9..df0f52bd18b4 100644
--- a/arch/parisc/include/asm/cache.h
+++ b/arch/parisc/include/asm/cache.h
@@ -22,6 +22,9 @@
 
 #define __read_mostly __attribute__((__section__(".data..read_mostly")))
 
+/* Read-only memory is marked before mark_rodata_ro() is called. */
+#define __ro_after_init	__read_mostly
+
 void parisc_cache_init(void);	/* initializes cache-flushing */
 void disable_sr_hashing_asm(int); /* low level support for above */
 void disable_sr_hashing(void);   /* turns off space register hashing */
diff --git a/arch/parisc/include/asm/cacheflush.h b/arch/parisc/include/asm/cacheflush.h
index 845272ce9cc5..7bd69bd43a01 100644
--- a/arch/parisc/include/asm/cacheflush.h
+++ b/arch/parisc/include/asm/cacheflush.h
@@ -121,10 +121,6 @@ flush_anon_page(struct vm_area_struct *vma, struct page *page, unsigned long vma
 	}
 }
 
-#ifdef CONFIG_DEBUG_RODATA
-void mark_rodata_ro(void);
-#endif
-
 #include <asm/kmap_types.h>
 
 #define ARCH_HAS_KMAP
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index c46662f64c39..b1051057e5b0 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -303,6 +303,9 @@ config ARCH_SUPPORTS_UPROBES
 config FIX_EARLYCON_MEM
 	def_bool y
 
+config DEBUG_RODATA
+	def_bool y
+
 config PGTABLE_LEVELS
 	int
 	default 4 if X86_64
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 9b18ed97a8a2..7816b7b276f4 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -74,28 +74,16 @@ config EFI_PGT_DUMP
 	  issues with the mapping of the EFI runtime regions into that
 	  table.
 
-config DEBUG_RODATA
-	bool "Write protect kernel read-only data structures"
-	default y
-	depends on DEBUG_KERNEL
-	---help---
-	  Mark the kernel read-only data as write-protected in the pagetables,
-	  in order to catch accidental (and incorrect) writes to such const
-	  data. This is recommended so that we can catch kernel bugs sooner.
-	  If in doubt, say "Y".
-
 config DEBUG_RODATA_TEST
-	bool "Testcase for the DEBUG_RODATA feature"
-	depends on DEBUG_RODATA
+	bool "Testcase for the marking rodata read-only"
 	default y
 	---help---
-	  This option enables a testcase for the DEBUG_RODATA
-	  feature as well as for the change_page_attr() infrastructure.
+	  This option enables a testcase for the setting rodata read-only
+	  as well as for the change_page_attr() infrastructure.
 	  If in doubt, say "N"
 
 config DEBUG_WX
 	bool "Warn on W+X mappings at boot"
-	depends on DEBUG_RODATA
 	select X86_PTDUMP_CORE
 	---help---
 	  Generate a warning if any W+X mappings are found at boot.
diff --git a/arch/x86/entry/vdso/vdso2c.h b/arch/x86/entry/vdso/vdso2c.h
index 0224987556ce..3f69326ed545 100644
--- a/arch/x86/entry/vdso/vdso2c.h
+++ b/arch/x86/entry/vdso/vdso2c.h
@@ -140,7 +140,7 @@ static void BITSFUNC(go)(void *raw_addr, size_t raw_len,
 	fprintf(outfile, "#include <asm/vdso.h>\n");
 	fprintf(outfile, "\n");
 	fprintf(outfile,
-		"static unsigned char raw_data[%lu] __page_aligned_data = {",
+		"static unsigned char raw_data[%lu] __ro_after_init __aligned(PAGE_SIZE) = {",
 		mapping_size);
 	for (j = 0; j < stripped_len; j++) {
 		if (j % 10 == 0)
diff --git a/arch/x86/include/asm/cacheflush.h b/arch/x86/include/asm/cacheflush.h
index e63aa38e85fb..61518cf79437 100644
--- a/arch/x86/include/asm/cacheflush.h
+++ b/arch/x86/include/asm/cacheflush.h
@@ -91,16 +91,10 @@ void clflush_cache_range(void *addr, unsigned int size);
 
 #define mmio_flush_range(addr, size) clflush_cache_range(addr, size)
 
-#ifdef CONFIG_DEBUG_RODATA
-void mark_rodata_ro(void);
 extern const int rodata_test_data;
 extern int kernel_set_to_readonly;
 void set_kernel_text_rw(void);
 void set_kernel_text_ro(void);
-#else
-static inline void set_kernel_text_rw(void) { }
-static inline void set_kernel_text_ro(void) { }
-#endif
 
 #ifdef CONFIG_DEBUG_RODATA_TEST
 int rodata_test(void);
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index c1adf33fdd0d..bc62e7cbf1b1 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -17,15 +17,8 @@ static inline bool kvm_check_and_clear_guest_paused(void)
 }
 #endif /* CONFIG_KVM_GUEST */
 
-#ifdef CONFIG_DEBUG_RODATA
 #define KVM_HYPERCALL \
         ALTERNATIVE(".byte 0x0f,0x01,0xc1", ".byte 0x0f,0x01,0xd9", X86_FEATURE_VMMCALL)
-#else
-/* On AMD processors, vmcall will generate a trap that we will
- * then rewrite to the appropriate instruction.
- */
-#define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1"
-#endif
 
 /* For KVM hypercalls, a three-byte sequence of either the vmcall or the vmmcall
  * instruction.  The hypervisor may replace it with something else but only the
diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h
index 0a5242428659..13b6cdd0af57 100644
--- a/arch/x86/include/asm/sections.h
+++ b/arch/x86/include/asm/sections.h
@@ -7,7 +7,7 @@
 extern char __brk_base[], __brk_limit[];
 extern struct exception_table_entry __stop___ex_table[];
 
-#if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
+#if defined(CONFIG_X86_64)
 extern char __end_rodata_hpage_align[];
 #endif
 
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 29408d6d6626..05c9e3f5b6d7 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -81,9 +81,9 @@ within(unsigned long addr, unsigned long start, unsigned long end)
 static unsigned long text_ip_addr(unsigned long ip)
 {
 	/*
-	 * On x86_64, kernel text mappings are mapped read-only with
-	 * CONFIG_DEBUG_RODATA. So we use the kernel identity mapping instead
-	 * of the kernel text mapping to modify the kernel text.
+	 * On x86_64, kernel text mappings are mapped read-only, so we use
+	 * the kernel identity mapping instead of the kernel text mapping
+	 * to modify the kernel text.
 	 *
 	 * For 32bit kernels, these mappings are same and we can use
 	 * kernel identity mapping to modify code.
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index 44256a62702b..ed15cd486d06 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -750,9 +750,7 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 {
 	int err;
-#ifdef CONFIG_DEBUG_RODATA
 	char opc[BREAK_INSTR_SIZE];
-#endif /* CONFIG_DEBUG_RODATA */
 
 	bpt->type = BP_BREAKPOINT;
 	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
@@ -761,7 +759,6 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 		return err;
 	err = probe_kernel_write((char *)bpt->bpt_addr,
 				 arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE);
-#ifdef CONFIG_DEBUG_RODATA
 	if (!err)
 		return err;
 	/*
@@ -778,13 +775,12 @@ int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 	if (memcmp(opc, arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE))
 		return -EINVAL;
 	bpt->type = BP_POKE_BREAKPOINT;
-#endif /* CONFIG_DEBUG_RODATA */
+
 	return err;
 }
 
 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 {
-#ifdef CONFIG_DEBUG_RODATA
 	int err;
 	char opc[BREAK_INSTR_SIZE];
 
@@ -801,8 +797,8 @@ int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 	if (err || memcmp(opc, bpt->saved_instr, BREAK_INSTR_SIZE))
 		goto knl_write;
 	return err;
+
 knl_write:
-#endif /* CONFIG_DEBUG_RODATA */
 	return probe_kernel_write((char *)bpt->bpt_addr,
 				  (char *)bpt->saved_instr, BREAK_INSTR_SIZE);
 }
diff --git a/arch/x86/kernel/test_nx.c b/arch/x86/kernel/test_nx.c
index 3f92ce07e525..27538f183c3b 100644
--- a/arch/x86/kernel/test_nx.c
+++ b/arch/x86/kernel/test_nx.c
@@ -142,7 +142,6 @@ static int test_NX(void)
 	 * by the error message
 	 */
 
-#ifdef CONFIG_DEBUG_RODATA
 	/* Test 3: Check if the .rodata section is executable */
 	if (rodata_test_data != 0xC3) {
 		printk(KERN_ERR "test_nx: .rodata marker has invalid value\n");
@@ -151,7 +150,6 @@ static int test_NX(void)
 		printk(KERN_ERR "test_nx: .rodata section is executable\n");
 		ret = -ENODEV;
 	}
-#endif
 
 #if 0
 	/* Test 4: Check if the .data section of a module is executable */
diff --git a/arch/x86/kernel/test_rodata.c b/arch/x86/kernel/test_rodata.c
index 5ecbfe5099da..cb4a01b41e27 100644
--- a/arch/x86/kernel/test_rodata.c
+++ b/arch/x86/kernel/test_rodata.c
@@ -76,5 +76,5 @@ int rodata_test(void)
 }
 
 MODULE_LICENSE("GPL");
-MODULE_DESCRIPTION("Testcase for the DEBUG_RODATA infrastructure");
+MODULE_DESCRIPTION("Testcase for marking rodata as read-only");
 MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 74e4bf11f562..fe133b710bef 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -41,29 +41,28 @@ ENTRY(phys_startup_64)
 jiffies_64 = jiffies;
 #endif
 
-#if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
+#if defined(CONFIG_X86_64)
 /*
- * On 64-bit, align RODATA to 2MB so that even with CONFIG_DEBUG_RODATA
- * we retain large page mappings for boundaries spanning kernel text, rodata
- * and data sections.
+ * On 64-bit, align RODATA to 2MB so we retain large page mappings for
+ * boundaries spanning kernel text, rodata and data sections.
  *
  * However, kernel identity mappings will have different RWX permissions
  * to the pages mapping to text and to the pages padding (which are freed) the
  * text section. Hence kernel identity mappings will be broken to smaller
  * pages. For 64-bit, kernel text and kernel identity mappings are different,
- * so we can enable protection checks that come with CONFIG_DEBUG_RODATA,
- * as well as retain 2MB large page mappings for kernel text.
+ * so we can enable protection checks as well as retain 2MB large page
+ * mappings for kernel text.
  */
-#define X64_ALIGN_DEBUG_RODATA_BEGIN	. = ALIGN(HPAGE_SIZE);
+#define X64_ALIGN_RODATA_BEGIN	. = ALIGN(HPAGE_SIZE);
 
-#define X64_ALIGN_DEBUG_RODATA_END				\
+#define X64_ALIGN_RODATA_END					\
 		. = ALIGN(HPAGE_SIZE);				\
 		__end_rodata_hpage_align = .;
 
 #else
 
-#define X64_ALIGN_DEBUG_RODATA_BEGIN
-#define X64_ALIGN_DEBUG_RODATA_END
+#define X64_ALIGN_RODATA_BEGIN
+#define X64_ALIGN_RODATA_END
 
 #endif
 
@@ -112,13 +111,11 @@ SECTIONS
 
 	EXCEPTION_TABLE(16) :text = 0x9090
 
-#if defined(CONFIG_DEBUG_RODATA)
 	/* .text should occupy whole number of pages */
 	. = ALIGN(PAGE_SIZE);
-#endif
-	X64_ALIGN_DEBUG_RODATA_BEGIN
+	X64_ALIGN_RODATA_BEGIN
 	RO_DATA(PAGE_SIZE)
-	X64_ALIGN_DEBUG_RODATA_END
+	X64_ALIGN_RODATA_END
 
 	/* Data */
 	.data : AT(ADDR(.data) - LOAD_OFFSET) {
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index cb4ef3de61f9..2ebfbaf61142 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -871,7 +871,6 @@ static noinline int do_test_wp_bit(void)
 	return flag;
 }
 
-#ifdef CONFIG_DEBUG_RODATA
 const int rodata_test_data = 0xC3;
 EXPORT_SYMBOL_GPL(rodata_test_data);
 
@@ -960,5 +959,3 @@ void mark_rodata_ro(void)
 	if (__supported_pte_mask & _PAGE_NX)
 		debug_checkwx();
 }
-#endif
-
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 5488d21123bd..a40b755c67e3 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -1074,7 +1074,6 @@ void __init mem_init(void)
 	mem_init_print_info(NULL);
 }
 
-#ifdef CONFIG_DEBUG_RODATA
 const int rodata_test_data = 0xC3;
 EXPORT_SYMBOL_GPL(rodata_test_data);
 
@@ -1166,8 +1165,6 @@ void mark_rodata_ro(void)
 	debug_checkwx();
 }
 
-#endif
-
 int kern_addr_valid(unsigned long addr)
 {
 	unsigned long above = ((long)addr) >> __VIRTUAL_MASK_SHIFT;
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 9cf96d82147a..1c37e650acac 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -283,7 +283,7 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
 		   __pa_symbol(__end_rodata) >> PAGE_SHIFT))
 		pgprot_val(forbidden) |= _PAGE_RW;
 
-#if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
+#if defined(CONFIG_X86_64)
 	/*
 	 * Once the kernel maps the text as RO (kernel_set_to_readonly is set),
 	 * kernel text mappings for the large page aligned text, rodata sections