Merge tag 'rodata-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/ke…

…rnel/git/kees/linux

Pull rodata updates from Kees Cook:
 "This renames the (now inaccurate) DEBUG_RODATA and related
  SET_MODULE_RONX configs to the more sensible STRICT_KERNEL_RWX and
  STRICT_MODULE_RWX"

* tag 'rodata-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  arch: Rename CONFIG_DEBUG_RODATA and CONFIG_DEBUG_MODULE_RONX
  arch: Move CONFIG_DEBUG_RODATA and CONFIG_SET_MODULE_RONX to be common

Documentation/DocBook/kgdb.tmpl

@@ -115,12 +115,12 @@
     </para>
     <para>
     If the architecture that you are using supports the kernel option
-    CONFIG_DEBUG_RODATA, you should consider turning it off.  This
+    CONFIG_STRICT_KERNEL_RWX, you should consider turning it off.  This
     option will prevent the use of software breakpoints because it
     marks certain regions of the kernel's memory space as read-only.
     If kgdb supports it for the architecture you are using, you can
     use hardware breakpoints if you desire to run with the
-    CONFIG_DEBUG_RODATA option turned on, else you need to turn off
+    CONFIG_STRICT_KERNEL_RWX option turned on, else you need to turn off
     this option.
     </para>
     <para>
@@ -135,7 +135,7 @@
     <para>Here is an example set of .config symbols to enable or
     disable for kgdb:
     <itemizedlist>
-    <listitem><para># CONFIG_DEBUG_RODATA is not set</para></listitem>
+    <listitem><para># CONFIG_STRICT_KERNEL_RWX is not set</para></listitem>
     <listitem><para>CONFIG_FRAME_POINTER=y</para></listitem>
     <listitem><para>CONFIG_KGDB=y</para></listitem>
     <listitem><para>CONFIG_KGDB_SERIAL_CONSOLE=y</para></listitem>
@@ -166,7 +166,7 @@
     </para>
     <para>Here is an example set of .config symbols to enable/disable kdb:
     <itemizedlist>
-    <listitem><para># CONFIG_DEBUG_RODATA is not set</para></listitem>
+    <listitem><para># CONFIG_STRICT_KERNEL_RWX is not set</para></listitem>
     <listitem><para>CONFIG_FRAME_POINTER=y</para></listitem>
     <listitem><para>CONFIG_KGDB=y</para></listitem>
     <listitem><para>CONFIG_KGDB_SERIAL_CONSOLE=y</para></listitem>

Documentation/security/self-protection.txt

@@ -51,11 +51,17 @@ kernel, they are implemented in a way where the memory is temporarily
 made writable during the update, and then returned to the original
 permissions.)
 
-In support of this are (the poorly named) CONFIG_DEBUG_RODATA and
-CONFIG_DEBUG_SET_MODULE_RONX, which seek to make sure that code is not
+In support of this are CONFIG_STRICT_KERNEL_RWX and
+CONFIG_STRICT_MODULE_RWX, which seek to make sure that code is not
 writable, data is not executable, and read-only data is neither writable
 nor executable.
 
+Most architectures have these options on by default and not user selectable.
+For some architectures like arm that wish to have these be selectable,
+the architecture Kconfig can select ARCH_OPTIONAL_KERNEL_RWX to enable
+a Kconfig prompt. CONFIG_ARCH_OPTIONAL_KERNEL_RWX_DEFAULT determines
+the default setting when ARCH_OPTIONAL_KERNEL_RWX is enabled.
+
 #### Function pointers and sensitive variables must not be writable
 
 Vast areas of kernel memory contain function pointers that are looked

arch/Kconfig

@@ -781,4 +781,38 @@ config VMAP_STACK
 	  the stack to map directly to the KASAN shadow map using a formula
 	  that is incorrect if the stack is in vmalloc space.
 
+config ARCH_OPTIONAL_KERNEL_RWX
+	def_bool n
+
+config ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
+	def_bool n
+
+config ARCH_HAS_STRICT_KERNEL_RWX
+	def_bool n
+
+config STRICT_KERNEL_RWX
+	bool "Make kernel text and rodata read-only" if ARCH_OPTIONAL_KERNEL_RWX
+	depends on ARCH_HAS_STRICT_KERNEL_RWX
+	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
+	help
+	  If this is set, kernel text and rodata memory will be made read-only,
+	  and non-text memory will be made non-executable. This provides
+	  protection against certain security exploits (e.g. executing the heap
+	  or modifying text)
+
+	  These features are considered standard security practice these days.
+	  You should say Y here in almost all cases.
+
+config ARCH_HAS_STRICT_MODULE_RWX
+	def_bool n
+
+config STRICT_MODULE_RWX
+	bool "Set loadable kernel module data as NX and text as RO" if ARCH_OPTIONAL_KERNEL_RWX
+	depends on ARCH_HAS_STRICT_MODULE_RWX && MODULES
+	default !ARCH_OPTIONAL_KERNEL_RWX || ARCH_OPTIONAL_KERNEL_RWX_DEFAULT
+	help
+	  If this is set, module text and rodata memory will be made read-only,
+	  and non-text memory will be made non-executable. This provides
+	  protection against certain security exploits (e.g. writing to text)
+
 source "kernel/gcov/Kconfig"

arch/arm/Kconfig

@@ -4,10 +4,14 @@ config ARM
 	select ARCH_CLOCKSOURCE_DATA
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_ELF_RANDOMIZE
+	select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
+	select ARCH_HAS_STRICT_MODULE_RWX if MMU
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_HAVE_CUSTOM_GPIO_H
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_MIGHT_HAVE_PC_PARPORT
+	select ARCH_OPTIONAL_KERNEL_RWX if ARCH_HAS_STRICT_KERNEL_RWX
+	select ARCH_OPTIONAL_KERNEL_RWX_DEFAULT if CPU_V7
 	select ARCH_SUPPORTS_ATOMIC_RMW
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_CMPXCHG_LOCKREF

arch/arm/Kconfig.debug

@@ -1738,17 +1738,6 @@ config PID_IN_CONTEXTIDR
 	  additional instructions during context switch. Say Y here only if you
 	  are planning to use hardware trace tools with this kernel.
 
-config DEBUG_SET_MODULE_RONX
-	bool "Set loadable kernel module data as NX and text as RO"
-	depends on MODULES && MMU
-	---help---
-	  This option helps catch unintended modifications to loadable
-	  kernel module's text and read-only data. It also prevents execution
-	  of module data. Such protection may interfere with run-time code
-	  patching and dynamic kernel tracing - and they might also protect
-	  against certain classes of kernel exploits.
-	  If in doubt, say "N".
-
 source "drivers/hwtracing/coresight/Kconfig"
 
 endmenu

arch/arm/configs/aspeed_g4_defconfig

@@ -25,7 +25,6 @@ CONFIG_MODULE_UNLOAD=y
 # CONFIG_ARCH_MULTI_V7 is not set
 CONFIG_ARCH_ASPEED=y
 CONFIG_MACH_ASPEED_G4=y
-CONFIG_DEBUG_RODATA=y
 CONFIG_AEABI=y
 CONFIG_UACCESS_WITH_MEMCPY=y
 CONFIG_SECCOMP=y
@@ -79,7 +78,8 @@ CONFIG_DEBUG_LL_UART_8250=y
 CONFIG_DEBUG_UART_PHYS=0x1e784000
 CONFIG_DEBUG_UART_VIRT=0xe8784000
 CONFIG_EARLY_PRINTK=y
-CONFIG_DEBUG_SET_MODULE_RONX=y
+CONFIG_STRICT_MODULE_RWX=y
+CONFIG_STRICT_KERNEL_RWX=y
 # CONFIG_XZ_DEC_X86 is not set
 # CONFIG_XZ_DEC_POWERPC is not set
 # CONFIG_XZ_DEC_IA64 is not set

arch/arm/configs/aspeed_g5_defconfig

@@ -26,7 +26,6 @@ CONFIG_ARCH_MULTI_V6=y
 # CONFIG_ARCH_MULTI_V7 is not set
 CONFIG_ARCH_ASPEED=y
 CONFIG_MACH_ASPEED_G5=y
-CONFIG_DEBUG_RODATA=y
 CONFIG_AEABI=y
 CONFIG_UACCESS_WITH_MEMCPY=y
 CONFIG_SECCOMP=y
@@ -81,7 +80,8 @@ CONFIG_DEBUG_LL_UART_8250=y
 CONFIG_DEBUG_UART_PHYS=0x1e784000
 CONFIG_DEBUG_UART_VIRT=0xe8784000
 CONFIG_EARLY_PRINTK=y
-CONFIG_DEBUG_SET_MODULE_RONX=y
+CONFIG_STRICT_MODULE_RWX=y
+CONFIG_STRICT_KERNEL_RWX=y
 # CONFIG_XZ_DEC_X86 is not set
 # CONFIG_XZ_DEC_POWERPC is not set
 # CONFIG_XZ_DEC_IA64 is not set

arch/arm/include/asm/cacheflush.h

@@ -490,7 +490,7 @@ static inline int set_memory_x(unsigned long addr, int numpages) { return 0; }
 static inline int set_memory_nx(unsigned long addr, int numpages) { return 0; }
 #endif
 
-#ifdef CONFIG_DEBUG_RODATA
+#ifdef CONFIG_STRICT_KERNEL_RWX
 void set_kernel_text_rw(void);
 void set_kernel_text_ro(void);
 #else

arch/arm/kernel/patch.c

@@ -24,9 +24,9 @@ static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
 	bool module = !core_kernel_text(uintaddr);
 	struct page *page;
 
-	if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
+	if (module && IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
 		page = vmalloc_to_page(addr);
-	else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA))
+	else if (!module && IS_ENABLED(CONFIG_STRICT_KERNEL_RWX))
 		page = virt_to_page(addr);
 	else
 		return addr;

arch/arm/kernel/vmlinux.lds.S

@@ -97,7 +97,7 @@ SECTIONS
 		HEAD_TEXT
 	}
 
-#ifdef CONFIG_DEBUG_RODATA
+#ifdef CONFIG_STRICT_KERNEL_RWX
 	. = ALIGN(1<<SECTION_SHIFT);
 #endif
 
@@ -158,7 +158,7 @@ SECTIONS
 
 	NOTES
 
-#ifdef CONFIG_DEBUG_RODATA
+#ifdef CONFIG_STRICT_KERNEL_RWX
 	. = ALIGN(1<<SECTION_SHIFT);
 #else
 	. = ALIGN(PAGE_SIZE);
@@ -230,7 +230,7 @@ SECTIONS
 	PERCPU_SECTION(L1_CACHE_BYTES)
 #endif
 
-#ifdef CONFIG_DEBUG_RODATA
+#ifdef CONFIG_STRICT_KERNEL_RWX
 	. = ALIGN(1<<SECTION_SHIFT);
 #else
 	. = ALIGN(THREAD_SIZE);
@@ -325,7 +325,7 @@ SECTIONS
 	STABS_DEBUG
 }
 
-#ifdef CONFIG_DEBUG_RODATA
+#ifdef CONFIG_STRICT_KERNEL_RWX
 /*
  * Without CONFIG_DEBUG_ALIGN_RODATA, __start_rodata_section_aligned will
  * be the first section-aligned location after __start_rodata. Otherwise,

arch/arm/mm/Kconfig

@@ -1051,21 +1051,9 @@ config ARCH_SUPPORTS_BIG_ENDIAN
 	  This option specifies the architecture can support big endian
 	  operation.
 
-config DEBUG_RODATA
-	bool "Make kernel text and rodata read-only"
-	depends on MMU && !XIP_KERNEL
-	default y if CPU_V7
-	help
-	  If this is set, kernel text and rodata memory will be made
-	  read-only, and non-text kernel memory will be made non-executable.
-	  The tradeoff is that each region is padded to section-size (1MiB)
-	  boundaries (because their permissions are different and splitting
-	  the 1M pages into 4K ones causes TLB performance problems), which
-	  can waste memory.
-
 config DEBUG_ALIGN_RODATA
 	bool "Make rodata strictly non-executable"
-	depends on DEBUG_RODATA
+	depends on STRICT_KERNEL_RWX
 	default y
 	help
 	  If this is set, rodata will be made explicitly non-executable. This

arch/arm/mm/init.c

@@ -572,7 +572,7 @@ void __init mem_init(void)
 	}
 }
 
-#ifdef CONFIG_DEBUG_RODATA
+#ifdef CONFIG_STRICT_KERNEL_RWX
 struct section_perm {
 	const char *name;
 	unsigned long start;
@@ -741,7 +741,7 @@ void set_kernel_text_ro(void)
 
 #else
 static inline void fix_kernmem_perms(void) { }
-#endif /* CONFIG_DEBUG_RODATA */
+#endif /* CONFIG_STRICT_KERNEL_RWX */
 
 void free_tcmmem(void)
 {

arch/arm64/Kconfig

@@ -13,6 +13,8 @@ config ARM64
 	select ARCH_HAS_GIGANTIC_PAGE
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_SG_CHAIN
+	select ARCH_HAS_STRICT_KERNEL_RWX
+	select ARCH_HAS_STRICT_MODULE_RWX
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
 	select ARCH_USE_CMPXCHG_LOCKREF
 	select ARCH_SUPPORTS_ATOMIC_RMW
@@ -123,9 +125,6 @@ config ARCH_PHYS_ADDR_T_64BIT
 config MMU
 	def_bool y
 
-config DEBUG_RODATA
-	def_bool y
-
 config ARM64_PAGE_SHIFT
 	int
 	default 16 if ARM64_64K_PAGES

arch/arm64/Kconfig.debug

@@ -71,19 +71,8 @@ config DEBUG_WX
 
 	  If in doubt, say "Y".
 
-config DEBUG_SET_MODULE_RONX
-	bool "Set loadable kernel module data as NX and text as RO"
-	depends on MODULES
-	default y
-	help
-	  Is this is set, kernel module text and rodata will be made read-only.
-	  This is to help catch accidental or malicious attempts to change the
-	  kernel's executable code.
-
-	  If in doubt, say Y.
-
 config DEBUG_ALIGN_RODATA
-	depends on DEBUG_RODATA
+	depends on STRICT_KERNEL_RWX
 	bool "Align linker sections up to SECTION_SIZE"
 	help
 	  If this option is enabled, sections that may potentially be marked as

arch/arm64/kernel/insn.c

@@ -93,7 +93,7 @@ static void __kprobes *patch_map(void *addr, int fixmap)
 	bool module = !core_kernel_text(uintaddr);
 	struct page *page;
 
-	if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX))
+	if (module && IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
 		page = vmalloc_to_page(addr);
 	else if (!module)
 		page = pfn_to_page(PHYS_PFN(__pa(addr)));

arch/parisc/Kconfig

@@ -8,6 +8,7 @@ config PARISC
 	select HAVE_SYSCALL_TRACEPOINTS
 	select ARCH_WANT_FRAME_POINTERS
 	select ARCH_HAS_ELF_RANDOMIZE
+	select ARCH_HAS_STRICT_KERNEL_RWX
 	select RTC_CLASS
 	select RTC_DRV_GENERIC
 	select INIT_ALL_POSSIBLE

arch/parisc/Kconfig.debug

@@ -5,15 +5,4 @@ source "lib/Kconfig.debug"
 config TRACE_IRQFLAGS_SUPPORT
 	def_bool y
 
-config DEBUG_RODATA
-       bool "Write protect kernel read-only data structures"
-       depends on DEBUG_KERNEL
-       default y
-       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 option may have a slight performance impact because a
-         portion of the kernel code won't be covered by a TLB anymore.
-         If in doubt, say "N".
-
 endmenu

arch/parisc/configs/712_defconfig

@@ -182,7 +182,6 @@ CONFIG_DEBUG_FS=y
 CONFIG_DEBUG_KERNEL=y
 CONFIG_DEBUG_MUTEXES=y
 # CONFIG_RCU_CPU_STALL_DETECTOR is not set
-CONFIG_DEBUG_RODATA=y
 CONFIG_CRYPTO_NULL=m
 CONFIG_CRYPTO_TEST=m
 CONFIG_CRYPTO_HMAC=y

arch/parisc/configs/c3000_defconfig

@@ -166,7 +166,6 @@ CONFIG_DEBUG_KERNEL=y
 CONFIG_DEBUG_MUTEXES=y
 # CONFIG_DEBUG_BUGVERBOSE is not set
 # CONFIG_RCU_CPU_STALL_DETECTOR is not set
-CONFIG_DEBUG_RODATA=y
 CONFIG_CRYPTO_NULL=m
 CONFIG_CRYPTO_TEST=m
 CONFIG_CRYPTO_MD5=m

arch/parisc/mm/init.c

@@ -545,7 +545,7 @@ void free_initmem(void)
 }
 
 
-#ifdef CONFIG_DEBUG_RODATA
+#ifdef CONFIG_STRICT_KERNEL_RWX
 void mark_rodata_ro(void)
 {
 	/* rodata memory was already mapped with KERNEL_RO access rights by

arch/s390/Kconfig

@@ -62,9 +62,6 @@ config PCI_QUIRKS
 config ARCH_SUPPORTS_UPROBES
 	def_bool y
 
-config DEBUG_RODATA
-	def_bool y
-
 config S390
 	def_bool y
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
@@ -73,6 +70,8 @@ config S390
 	select ARCH_HAS_GIGANTIC_PAGE
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_SG_CHAIN
+	select ARCH_HAS_STRICT_KERNEL_RWX
+	select ARCH_HAS_STRICT_MODULE_RWX
 	select ARCH_HAS_UBSAN_SANITIZE_ALL
 	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select ARCH_INLINE_READ_LOCK

arch/s390/Kconfig.debug

@@ -17,7 +17,4 @@ config S390_PTDUMP
 	  kernel.
 	  If in doubt, say "N"
 
-config DEBUG_SET_MODULE_RONX
-	def_bool y
-	depends on MODULES
 endmenu