| Message ID | 1484789346-21012-2-git-send-email-labbott@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed 2017-01-18 17:29:05, Laura Abbott wrote: > > Despite the word 'debug' in CONFIG_DEBUG_RODATA, this kernel option > provides key security features that are to be expected on a modern > system. Change the name to CONFIG_HARDENED_PAGE_MAPPINGS which more > accurately describes what this option is intended to do. I think this is bad change. CONFIG_DEBUG_RODATA is describing what it does, CONFIG_HARDENED_PAGE_MAPPINGS is advertising. We don't do advertising, and we don't force people to re-answer the config questions without good reason. CONFIG_HARDENED_RODATA might fix the first problem, but not the second one. Pavel > Signed-off-by: Laura Abbott <labbott@redhat.com> > --- > Documentation/DocBook/kgdb.tmpl | 8 ++++---- > Documentation/security/self-protection.txt | 2 +- > arch/arm/Kconfig | 1 + > arch/arm/configs/aspeed_g4_defconfig | 2 +- > arch/arm/configs/aspeed_g5_defconfig | 2 +- > arch/arm/include/asm/cacheflush.h | 2 +- > arch/arm/kernel/patch.c | 2 +- > arch/arm/kernel/vmlinux.lds.S | 8 ++++---- > arch/arm/mm/Kconfig | 14 +------------- > arch/arm/mm/init.c | 4 ++-- > arch/arm64/Kconfig | 4 +--- > arch/arm64/Kconfig.debug | 2 +- > arch/parisc/Kconfig | 1 + > arch/parisc/Kconfig.debug | 11 ----------- > arch/parisc/configs/712_defconfig | 2 +- > arch/parisc/configs/c3000_defconfig | 2 +- > arch/parisc/mm/init.c | 2 +- > arch/s390/Kconfig | 4 +--- > arch/x86/Kconfig | 4 +--- > include/linux/init.h | 4 ++-- > init/main.c | 4 ++-- > kernel/configs/android-recommended.config | 2 +- > kernel/power/hibernate.c | 2 +- > kernel/power/power.h | 4 ++-- > kernel/power/snapshot.c | 4 ++-- > security/Kconfig | 16 ++++++++++++++++ > 26 files changed, 51 insertions(+), 62 deletions(-) > > diff --git a/Documentation/DocBook/kgdb.tmpl b/Documentation/DocBook/kgdb.tmpl > index f3abca7..a79b638 100644 > --- a/Documentation/DocBook/kgdb.tmpl > +++ b/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_HARDENED_PAGE_MAPPINGS, 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_HARDENED_PAGE_MAPPINGS 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_HARDENED_PAGE_MAPPINGS 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_HARDENED_PAGE_MAPPINGS 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> > diff --git a/Documentation/security/self-protection.txt b/Documentation/security/self-protection.txt > index 3010576..da8cb36 100644 > --- a/Documentation/security/self-protection.txt > +++ b/Documentation/security/self-protection.txt > @@ -51,7 +51,7 @@ 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 > +In support of this are CONFIG_HARDENED_PAGE_MAPPINGS and > CONFIG_DEBUG_SET_MODULE_RONX, which seek to make sure that code is not > writable, data is not executable, and read-only data is neither writable > nor executable. > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index 186c4c2..09aff28 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -7,6 +7,7 @@ config ARM > select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST > select ARCH_HAVE_CUSTOM_GPIO_H > select ARCH_HAS_GCOV_PROFILE_ALL > + select ARCH_HAS_HARDENED_MAPPINGS if MMU && !XIP_KERNEL > select ARCH_MIGHT_HAVE_PC_PARPORT > select ARCH_SUPPORTS_ATOMIC_RMW > select ARCH_USE_BUILTIN_BSWAP > diff --git a/arch/arm/configs/aspeed_g4_defconfig b/arch/arm/configs/aspeed_g4_defconfig > index ca39c04..8ccc216 100644 > --- a/arch/arm/configs/aspeed_g4_defconfig > +++ b/arch/arm/configs/aspeed_g4_defconfig > @@ -25,7 +25,7 @@ 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_HARDENED_PAGE_MAPPINGS=y > CONFIG_AEABI=y > CONFIG_UACCESS_WITH_MEMCPY=y > CONFIG_SECCOMP=y > diff --git a/arch/arm/configs/aspeed_g5_defconfig b/arch/arm/configs/aspeed_g5_defconfig > index 4f366b0..90c5ce4 100644 > --- a/arch/arm/configs/aspeed_g5_defconfig > +++ b/arch/arm/configs/aspeed_g5_defconfig > @@ -26,7 +26,7 @@ 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_HARDENED_PAGE_MAPPINGS=y > CONFIG_AEABI=y > CONFIG_UACCESS_WITH_MEMCPY=y > CONFIG_SECCOMP=y > diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h > index bdd283b..c3a7a72 100644 > --- a/arch/arm/include/asm/cacheflush.h > +++ b/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_HARDENED_PAGE_MAPPINGS > void set_kernel_text_rw(void); > void set_kernel_text_ro(void); > #else > diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c > index 69bda1a..9da1bf5 100644 > --- a/arch/arm/kernel/patch.c > +++ b/arch/arm/kernel/patch.c > @@ -26,7 +26,7 @@ static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags) > > if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX)) > page = vmalloc_to_page(addr); > - else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA)) > + else if (!module && IS_ENABLED(CONFIG_HARDENED_PAGE_MAPPINGS)) > page = virt_to_page(addr); > else > return addr; > diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S > index f7f55df..5c6a2e8 100644 > --- a/arch/arm/kernel/vmlinux.lds.S > +++ b/arch/arm/kernel/vmlinux.lds.S > @@ -97,7 +97,7 @@ SECTIONS > HEAD_TEXT > } > > -#ifdef CONFIG_DEBUG_RODATA > +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS > . = ALIGN(1<<SECTION_SHIFT); > #endif > > @@ -158,7 +158,7 @@ SECTIONS > > NOTES > > -#ifdef CONFIG_DEBUG_RODATA > +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS > . = 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_HARDENED_PAGE_MAPPINGS > . = ALIGN(1<<SECTION_SHIFT); > #else > . = ALIGN(THREAD_SIZE); > @@ -325,7 +325,7 @@ SECTIONS > STABS_DEBUG > } > > -#ifdef CONFIG_DEBUG_RODATA > +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS > /* > * Without CONFIG_DEBUG_ALIGN_RODATA, __start_rodata_section_aligned will > * be the first section-aligned location after __start_rodata. Otherwise, > diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig > index f68e8ec..e770dc9 100644 > --- a/arch/arm/mm/Kconfig > +++ b/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 HARDENED_PAGE_MAPPINGS > default y > help > If this is set, rodata will be made explicitly non-executable. This > diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c > index 370581a..303bee4 100644 > --- a/arch/arm/mm/init.c > +++ b/arch/arm/mm/init.c > @@ -572,7 +572,7 @@ void __init mem_init(void) > } > } > > -#ifdef CONFIG_DEBUG_RODATA > +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS > 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_HARDENED_PAGE_MAPPINGS */ > > void free_tcmmem(void) > { > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 1117421..06fed56 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -11,6 +11,7 @@ config ARM64 > select ARCH_HAS_ELF_RANDOMIZE > select ARCH_HAS_GCOV_PROFILE_ALL > select ARCH_HAS_GIGANTIC_PAGE > + select ARCH_HAS_HARDENED_MAPPINGS > select ARCH_HAS_KCOV > select ARCH_HAS_SG_CHAIN > select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST > @@ -123,9 +124,6 @@ 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 > diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug > index d1ebd46..a26d27f 100644 > --- a/arch/arm64/Kconfig.debug > +++ b/arch/arm64/Kconfig.debug > @@ -83,7 +83,7 @@ config DEBUG_SET_MODULE_RONX > If in doubt, say Y. > > config DEBUG_ALIGN_RODATA > - depends on DEBUG_RODATA > + depends on ARCH_HAS_HARDENED_MAPPINGS > bool "Align linker sections up to SECTION_SIZE" > help > If this option is enabled, sections that may potentially be marked as > diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig > index 3a71f38..7c73eaa 100644 > --- a/arch/parisc/Kconfig > +++ b/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_HARDENED_MAPPINGS > select RTC_CLASS > select RTC_DRV_GENERIC > select INIT_ALL_POSSIBLE > diff --git a/arch/parisc/Kconfig.debug b/arch/parisc/Kconfig.debug > index 68b7cbd..0d856b9 100644 > --- a/arch/parisc/Kconfig.debug > +++ b/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 > diff --git a/arch/parisc/configs/712_defconfig b/arch/parisc/configs/712_defconfig > index db8f56b..f1a4732 100644 > --- a/arch/parisc/configs/712_defconfig > +++ b/arch/parisc/configs/712_defconfig > @@ -182,7 +182,7 @@ 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_HARDENED_PAGE_MAPPINGS=y > CONFIG_CRYPTO_NULL=m > CONFIG_CRYPTO_TEST=m > CONFIG_CRYPTO_HMAC=y > diff --git a/arch/parisc/configs/c3000_defconfig b/arch/parisc/configs/c3000_defconfig > index fb92b89..03e88e2 100644 > --- a/arch/parisc/configs/c3000_defconfig > +++ b/arch/parisc/configs/c3000_defconfig > @@ -166,7 +166,7 @@ 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_HARDENED_PAGE_MAPPINGS=y > CONFIG_CRYPTO_NULL=m > CONFIG_CRYPTO_TEST=m > CONFIG_CRYPTO_MD5=m > diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c > index e02ada3..f76f8ad 100644 > --- a/arch/parisc/mm/init.c > +++ b/arch/parisc/mm/init.c > @@ -545,7 +545,7 @@ void free_initmem(void) > } > > > -#ifdef CONFIG_DEBUG_RODATA > +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS > void mark_rodata_ro(void) > { > /* rodata memory was already mapped with KERNEL_RO access rights by > diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig > index c6722112..8e70ae5 100644 > --- a/arch/s390/Kconfig > +++ b/arch/s390/Kconfig > @@ -62,15 +62,13 @@ 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 > select ARCH_HAS_ELF_RANDOMIZE > select ARCH_HAS_GCOV_PROFILE_ALL > select ARCH_HAS_GIGANTIC_PAGE > + select ARCH_HAS_HARDENED_MAPPINGS > select ARCH_HAS_KCOV > select ARCH_HAS_SG_CHAIN > select ARCH_HAS_UBSAN_SANITIZE_ALL > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index e487493..9d80cd8 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -50,6 +50,7 @@ config X86 > select ARCH_HAS_ELF_RANDOMIZE > select ARCH_HAS_FAST_MULTIPLIER > select ARCH_HAS_GCOV_PROFILE_ALL > + select ARCH_HAS_HARDENED_MAPPINGS > select ARCH_HAS_KCOV if X86_64 > select ARCH_HAS_MMIO_FLUSH > select ARCH_HAS_PMEM_API if X86_64 > @@ -309,9 +310,6 @@ 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/include/linux/init.h b/include/linux/init.h > index 885c3e6..9967bc9 100644 > --- a/include/linux/init.h > +++ b/include/linux/init.h > @@ -126,10 +126,10 @@ void prepare_namespace(void); > void __init load_default_modules(void); > int __init init_rootfs(void); > > -#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX) > +#if defined(CONFIG_HARDENED_PAGE_MAPPINGS) || defined(CONFIG_DEBUG_SET_MODULE_RONX) > extern bool rodata_enabled; > #endif > -#ifdef CONFIG_DEBUG_RODATA > +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS > void mark_rodata_ro(void); > #endif > > diff --git a/init/main.c b/init/main.c > index b0c9d6f..4b3bcc4 100644 > --- a/init/main.c > +++ b/init/main.c > @@ -925,7 +925,7 @@ static int try_to_run_init_process(const char *init_filename) > > static noinline void __init kernel_init_freeable(void); > > -#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX) > +#if defined(CONFIG_HARDENED_PAGE_MAPPINGS) || defined(CONFIG_DEBUG_SET_MODULE_RONX) > bool rodata_enabled __ro_after_init = true; > static int __init set_debug_rodata(char *str) > { > @@ -934,7 +934,7 @@ static int __init set_debug_rodata(char *str) > __setup("rodata=", set_debug_rodata); > #endif > > -#ifdef CONFIG_DEBUG_RODATA > +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS > static void mark_readonly(void) > { > if (rodata_enabled) > diff --git a/kernel/configs/android-recommended.config b/kernel/configs/android-recommended.config > index 297756b..b796bc8 100644 > --- a/kernel/configs/android-recommended.config > +++ b/kernel/configs/android-recommended.config > @@ -11,7 +11,7 @@ CONFIG_BLK_DEV_LOOP=y > CONFIG_BLK_DEV_RAM=y > CONFIG_BLK_DEV_RAM_SIZE=8192 > CONFIG_COMPACTION=y > -CONFIG_DEBUG_RODATA=y > +CONFIG_HARDENED_PAGE_MAPPINGS=y > CONFIG_DM_CRYPT=y > CONFIG_DM_UEVENT=y > CONFIG_DM_VERITY=y > diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c > index b26dbc4..f7a3ea3 100644 > --- a/kernel/power/hibernate.c > +++ b/kernel/power/hibernate.c > @@ -1156,7 +1156,7 @@ static int __init hibernate_setup(char *str) > } else if (!strncmp(str, "no", 2)) { > noresume = 1; > nohibernate = 1; > - } else if (IS_ENABLED(CONFIG_DEBUG_RODATA) > + } else if (IS_ENABLED(CONFIG_HARDENED_PAGE_MAPPINGS) > && !strncmp(str, "protect_image", 13)) { > enable_restore_image_protection(); > } > diff --git a/kernel/power/power.h b/kernel/power/power.h > index 1dfa0da..dc2c7b8 100644 > --- a/kernel/power/power.h > +++ b/kernel/power/power.h > @@ -61,12 +61,12 @@ extern int hibernation_snapshot(int platform_mode); > extern int hibernation_restore(int platform_mode); > extern int hibernation_platform_enter(void); > > -#ifdef CONFIG_DEBUG_RODATA > +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS > /* kernel/power/snapshot.c */ > extern void enable_restore_image_protection(void); > #else > static inline void enable_restore_image_protection(void) {} > -#endif /* CONFIG_DEBUG_RODATA */ > +#endif /* CONFIG_HARDENED_PAGE_MAPPINGS */ > > #else /* !CONFIG_HIBERNATION */ > > diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c > index 2d8e2b2..a7c793e 100644 > --- a/kernel/power/snapshot.c > +++ b/kernel/power/snapshot.c > @@ -38,7 +38,7 @@ > > #include "power.h" > > -#ifdef CONFIG_DEBUG_RODATA > +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS > static bool hibernate_restore_protection; > static bool hibernate_restore_protection_active; > > @@ -73,7 +73,7 @@ static inline void hibernate_restore_protection_begin(void) {} > static inline void hibernate_restore_protection_end(void) {} > static inline void hibernate_restore_protect_page(void *page_address) {} > static inline void hibernate_restore_unprotect_page(void *page_address) {} > -#endif /* CONFIG_DEBUG_RODATA */ > +#endif /* CONFIG_HARDENED_PAGE_MAPPINGS */ > > static int swsusp_page_is_free(struct page *); > static void swsusp_set_page_forbidden(struct page *); > diff --git a/security/Kconfig b/security/Kconfig > index 118f454..ad6ce82 100644 > --- a/security/Kconfig > +++ b/security/Kconfig > @@ -158,6 +158,22 @@ config HARDENED_USERCOPY_PAGESPAN > been removed. This config is intended to be used only while > trying to find such users. > > +config ARCH_HAS_HARDENED_MAPPINGS > + def_bool n > + > +config HARDENED_PAGE_MAPPINGS > + bool "Mark kernel mappings with stricter permissions (RO/W^X)" > + default y > + depends on ARCH_HAS_HARDENED_MAPPINGS > + 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 attacks (e.g. executing the heap > + or modifying text). > + > + Unless your system has known restrictions or performance issues, it > + is recommended to say Y here. > + > source security/selinux/Kconfig > source security/smack/Kconfig > source security/tomoyo/Kconfig
Hi Laura, On Wed, Jan 18, 2017 at 05:29:05PM -0800, Laura Abbott wrote: > > Despite the word 'debug' in CONFIG_DEBUG_RODATA, this kernel option > provides key security features that are to be expected on a modern > system. Change the name to CONFIG_HARDENED_PAGE_MAPPINGS which more > accurately describes what this option is intended to do. This generally sounds good. Thanks for attacking this! On the bikeshedding front, *maybe* it would be nice to mention permissions in the name, something like STRICT_KERNEL_RWX. That might also prevent the reading of 'hardened' as 'optional overhead'. That said, the proposed name is fine by me -- I'm happy so long as 'DEBUG' goes. > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 1117421..06fed56 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -11,6 +11,7 @@ config ARM64 > select ARCH_HAS_ELF_RANDOMIZE > select ARCH_HAS_GCOV_PROFILE_ALL > select ARCH_HAS_GIGANTIC_PAGE > + select ARCH_HAS_HARDENED_MAPPINGS > select ARCH_HAS_KCOV > select ARCH_HAS_SG_CHAIN > select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST > @@ -123,9 +124,6 @@ config ARCH_PHYS_ADDR_T_64BIT > config MMU > def_bool y > > -config DEBUG_RODATA > - def_bool y > - > diff --git a/security/Kconfig b/security/Kconfig > index 118f454..ad6ce82 100644 > --- a/security/Kconfig > +++ b/security/Kconfig > @@ -158,6 +158,22 @@ config HARDENED_USERCOPY_PAGESPAN > been removed. This config is intended to be used only while > trying to find such users. > > +config ARCH_HAS_HARDENED_MAPPINGS > + def_bool n > + > +config HARDENED_PAGE_MAPPINGS > + bool "Mark kernel mappings with stricter permissions (RO/W^X)" > + default y > + depends on ARCH_HAS_HARDENED_MAPPINGS > + 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 attacks (e.g. executing the heap > + or modifying text). > + > + Unless your system has known restrictions or performance issues, it > + is recommended to say Y here. It's somewhat unfortunate that this means the feature is no longer mandatory on arm64 (and s390+x86). We have a boot-time switch to turn the protections off, so I was hoping we could make this mandatory on all architectures with support. It would be good to see if we could make this mandatory for arm and parisc, or if it really needs to be optional for either of those. Thanks, Mark.
On Thu, Jan 19, 2017 at 10:56:46AM +0000, Mark Rutland wrote: > > +config HARDENED_PAGE_MAPPINGS > > + bool "Mark kernel mappings with stricter permissions (RO/W^X)" > > + default y > > + depends on ARCH_HAS_HARDENED_MAPPINGS > > + 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 attacks (e.g. executing the heap > > + or modifying text). > > + > > + Unless your system has known restrictions or performance issues, it > > + is recommended to say Y here. > > It's somewhat unfortunate that this means the feature is no longer > mandatory on arm64 (and s390+x86). We have a boot-time switch to turn > the protections off, so I was hoping we could make this mandatory on all > architectures with support. > > It would be good to see if we could make this mandatory for arm and > parisc, or if it really needs to be optional for either of those. Looks like the config option is a no-op on parisc just like it is on s390. Irrelavant of the config option at least on s390 the page tables for kernel text and rodata will be read-only anyway. This works since ages and I don't see a reason why this should be changed. Also trying to disable this with the "rodata=" command line option does not work at least on s390, and I guess this is true for parisc as well. The only thing implemented with CONFIG_DEBUG_RODATA on both architectures is to emit a message that states memory has been protected (mark_rodata_ro). This just avoids a wrong "Kernel memory protection disabled." message. So yes, I'd really like to keep this option mandatory.
On 19.01.2017 12:33, Heiko Carstens wrote: > On Thu, Jan 19, 2017 at 10:56:46AM +0000, Mark Rutland wrote: >>> +config HARDENED_PAGE_MAPPINGS >>> + bool "Mark kernel mappings with stricter permissions (RO/W^X)" >>> + default y >>> + depends on ARCH_HAS_HARDENED_MAPPINGS >>> + 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 attacks (e.g. executing the heap >>> + or modifying text). >>> + >>> + Unless your system has known restrictions or performance issues, it >>> + is recommended to say Y here. >> >> It's somewhat unfortunate that this means the feature is no longer >> mandatory on arm64 (and s390+x86). We have a boot-time switch to turn >> the protections off, so I was hoping we could make this mandatory on all >> architectures with support. >> >> It would be good to see if we could make this mandatory for arm and >> parisc, or if it really needs to be optional for either of those. > > Looks like the config option is a no-op on parisc just like it is on > s390. Irrelavant of the config option at least on s390 the page tables for > kernel text and rodata will be read-only anyway. Right, that's true at the moment for parisc as well. I do have unfinished patches which will add runtime kernel patching for ftrace to parisc, and those patches will need to add code to enable/disable ro text/data like x86. > This works since ages and I don't see a reason why this should be > changed. Also trying to disable this with the "rodata=" command line option > does not work at least on s390, and I guess this is true for parisc as > well. I never tried the option itself, but it should work on parisc to disable the ro protection by this option. > The only thing implemented with CONFIG_DEBUG_RODATA on both architectures > is to emit a message that states memory has been protected > (mark_rodata_ro). > This just avoids a wrong "Kernel memory protection disabled." message. > > So yes, I'd really like to keep this option mandatory. I'd be fine with a rename of the config option to ARCH_HAS_HARDENED_MAPPINGS and keeping the "rodata=" command line. Helge
On Wed, Jan 18, 2017 at 5:29 PM, Laura Abbott <labbott@redhat.com> wrote: > > Despite the word 'debug' in CONFIG_DEBUG_RODATA, this kernel option > provides key security features that are to be expected on a modern > system. Change the name to CONFIG_HARDENED_PAGE_MAPPINGS which more > accurately describes what this option is intended to do. Oh thank you. Yes, this is badly needed. I might prefer to see this as two patches, though: Move DEBUG_RODATA to top-level arch/Kconfig, (and add ARCH_HAS_[bikeshed]). Rename DEBUG_RODATA to [bikeshed] (We should do a similar renaming for DEBUG_SET_MODULE_RONX too.) Another thing that might be even cleaner would be to entirely invert the logic. Something like CONFIG_ARCH_MISSING_[bikeshed]? > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index 186c4c2..09aff28 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -7,6 +7,7 @@ config ARM > select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST > select ARCH_HAVE_CUSTOM_GPIO_H > select ARCH_HAS_GCOV_PROFILE_ALL > + select ARCH_HAS_HARDENED_MAPPINGS if MMU && !XIP_KERNEL > select ARCH_MIGHT_HAVE_PC_PARPORT > select ARCH_SUPPORTS_ATOMIC_RMW > select ARCH_USE_BUILTIN_BSWAP > diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig > index f68e8ec..e770dc9 100644 > --- a/arch/arm/mm/Kconfig > +++ b/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 These changes aren't correctly representing the ARM state. I think the ARCH_HAS is correct, but I'm not sure the best way to include the "default y if CPU_V7". > --- a/security/Kconfig > +++ b/security/Kconfig > @@ -158,6 +158,22 @@ config HARDENED_USERCOPY_PAGESPAN > been removed. This config is intended to be used only while > trying to find such users. > > +config ARCH_HAS_HARDENED_MAPPINGS > + def_bool n > + > +config HARDENED_PAGE_MAPPINGS > + bool "Mark kernel mappings with stricter permissions (RO/W^X)" > + default y > + depends on ARCH_HAS_HARDENED_MAPPINGS > + 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 attacks (e.g. executing the heap > + or modifying text). > + > + Unless your system has known restrictions or performance issues, it > + is recommended to say Y here. > + > source security/selinux/Kconfig > source security/smack/Kconfig > source security/tomoyo/Kconfig Should this go in arch/Kconfig or security/Kconfig? I'm starting to think we need a top-level kernel security Kconfig (the gcc plugins are starting to pile up in arch/Kconfig, for example). I think since this is arch specific, maybe arch/Kconfig? (Arguably, HARDENED_USERCOPY shouldn't be in security/Kconfig either, since security/Kconfig is mostly LSM or userspace-facing stuff? I dunno.) As for the bikeshed on the naming, I like "KERNEL_RWX", and it likely doesn't need "STRICT", IMO. CONFIG_KERNEL_RWX ? I don't have a strong opinion beyond removing "DEBUG" from the name. :) -Kees
On Thu, Jan 19, 2017 at 2:56 AM, Mark Rutland <mark.rutland@arm.com> wrote: > Hi Laura, > > On Wed, Jan 18, 2017 at 05:29:05PM -0800, Laura Abbott wrote: >> diff --git a/security/Kconfig b/security/Kconfig >> index 118f454..ad6ce82 100644 >> --- a/security/Kconfig >> +++ b/security/Kconfig >> @@ -158,6 +158,22 @@ config HARDENED_USERCOPY_PAGESPAN >> been removed. This config is intended to be used only while >> trying to find such users. >> >> +config ARCH_HAS_HARDENED_MAPPINGS >> + def_bool n >> + >> +config HARDENED_PAGE_MAPPINGS >> + bool "Mark kernel mappings with stricter permissions (RO/W^X)" >> + default y >> + depends on ARCH_HAS_HARDENED_MAPPINGS >> + 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 attacks (e.g. executing the heap >> + or modifying text). >> + >> + Unless your system has known restrictions or performance issues, it >> + is recommended to say Y here. > > It's somewhat unfortunate that this means the feature is no longer > mandatory on arm64 (and s390+x86). We have a boot-time switch to turn > the protections off, so I was hoping we could make this mandatory on all > architectures with support. Oh, I totally missed this. Yes, we need it to stay mandatory. It should be possible by just adding "select HARDENED_PAGE_MAPPINGS" to the arch Kconfig, yes? > It would be good to see if we could make this mandatory for arm and > parisc, or if it really needs to be optional for either of those. (Adding mpe to CC...) Michael, what's needed to get this working on powerpc too? -Kees
On 01/19/2017 08:53 AM, Pavel Machek wrote: > On Wed 2017-01-18 17:29:05, Laura Abbott wrote: >> >> Despite the word 'debug' in CONFIG_DEBUG_RODATA, this kernel option >> provides key security features that are to be expected on a modern >> system. Change the name to CONFIG_HARDENED_PAGE_MAPPINGS which more >> accurately describes what this option is intended to do. > > I think this is bad change. CONFIG_DEBUG_RODATA is describing what it > does, CONFIG_HARDENED_PAGE_MAPPINGS is advertising. > > We don't do advertising, and we don't force people to re-answer the > config questions without good reason. > > CONFIG_HARDENED_RODATA might fix the first problem, but not the second > one. > > Pavel > (Apologies, my SMTP was set up incorrectly so my response didn't actually get sent out) CONFIG_DEBUG_RODATA isn't describing what it does though. It misses that this config may handle much more than just rodata. I think Mark Rutland's suggestion of STRICT_KERNEL_RWX might be more descriptive. Thanks, Laura
On 01/19/2017 11:56 AM, Mark Rutland wrote: > Hi Laura, > > On Wed, Jan 18, 2017 at 05:29:05PM -0800, Laura Abbott wrote: >> >> Despite the word 'debug' in CONFIG_DEBUG_RODATA, this kernel option >> provides key security features that are to be expected on a modern >> system. Change the name to CONFIG_HARDENED_PAGE_MAPPINGS which more >> accurately describes what this option is intended to do. > > This generally sounds good. Thanks for attacking this! > > On the bikeshedding front, *maybe* it would be nice to mention > permissions in the name, something like STRICT_KERNEL_RWX. That might > also prevent the reading of 'hardened' as 'optional overhead'. > > That said, the proposed name is fine by me -- I'm happy so long as > 'DEBUG' goes. > (Apologies for the delay, my SMTP was set up incorrectly so my messages didn't actually get sent out) I like that better since it's describing specifically what the config should be setting as opposed to something more vague. That might fit better with what Pavel was suggesting as well. Thanks, Laura
On 01/19/2017 12:33 PM, Heiko Carstens wrote: > On Thu, Jan 19, 2017 at 10:56:46AM +0000, Mark Rutland wrote: >>> +config HARDENED_PAGE_MAPPINGS >>> + bool "Mark kernel mappings with stricter permissions (RO/W^X)" >>> + default y >>> + depends on ARCH_HAS_HARDENED_MAPPINGS >>> + 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 attacks (e.g. executing the heap >>> + or modifying text). >>> + >>> + Unless your system has known restrictions or performance issues, it >>> + is recommended to say Y here. >> >> It's somewhat unfortunate that this means the feature is no longer >> mandatory on arm64 (and s390+x86). We have a boot-time switch to turn >> the protections off, so I was hoping we could make this mandatory on all >> architectures with support. >> >> It would be good to see if we could make this mandatory for arm and >> parisc, or if it really needs to be optional for either of those. > > Looks like the config option is a no-op on parisc just like it is on > s390. Irrelavant of the config option at least on s390 the page tables for > kernel text and rodata will be read-only anyway. > > This works since ages and I don't see a reason why this should be > changed. Also trying to disable this with the "rodata=" command line option > does not work at least on s390, and I guess this is true for parisc as > well. > > The only thing implemented with CONFIG_DEBUG_RODATA on both architectures > is to emit a message that states memory has been protected > (mark_rodata_ro). > This just avoids a wrong "Kernel memory protection disabled." message. > > So yes, I'd really like to keep this option mandatory. > (Apologies, my SMTP server was set up incorrectly so this didn't get sent out when I thought it did) Okay, that's useful to know. I think I'm going to add a 'select HARDENED_MAPPINGS' (or whatever it gets changed to) to arches that were previously def_bool. This is a slight Kconfig semantic change but as has been pointed out we now have the command line option. Thanks, Laura
On Wed 2017-01-25 12:21:05, Laura Abbott wrote: > On 01/19/2017 08:53 AM, Pavel Machek wrote: > >On Wed 2017-01-18 17:29:05, Laura Abbott wrote: > >> > >>Despite the word 'debug' in CONFIG_DEBUG_RODATA, this kernel option > >>provides key security features that are to be expected on a modern > >>system. Change the name to CONFIG_HARDENED_PAGE_MAPPINGS which more > >>accurately describes what this option is intended to do. > > > >I think this is bad change. CONFIG_DEBUG_RODATA is describing what it > >does, CONFIG_HARDENED_PAGE_MAPPINGS is advertising. > > > >We don't do advertising, and we don't force people to re-answer the > >config questions without good reason. > > > >CONFIG_HARDENED_RODATA might fix the first problem, but not the second > >one. > > > > Pavel > > > > (Apologies, my SMTP was set up incorrectly so my response didn't > actually get sent out) > > CONFIG_DEBUG_RODATA isn't describing what it does though. It misses > that this config may handle much more than just rodata. I think > Mark Rutland's suggestion of STRICT_KERNEL_RWX might be more > descriptive. CONFIG_BUG=y CONFIG_LBDAF=y CONFIG_PM_OPP=y ..it is config option. It is not description of the feature. People are living with that config option for a while. I'd keep it. Maybe you can go from CONFIG_DEBUG_RODATA to CONFIG_RODATA... (but you'll still have people re-answer config option.) Pavel
diff --git a/Documentation/DocBook/kgdb.tmpl b/Documentation/DocBook/kgdb.tmpl index f3abca7..a79b638 100644 --- a/Documentation/DocBook/kgdb.tmpl +++ b/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_HARDENED_PAGE_MAPPINGS, 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_HARDENED_PAGE_MAPPINGS 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_HARDENED_PAGE_MAPPINGS 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_HARDENED_PAGE_MAPPINGS 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> diff --git a/Documentation/security/self-protection.txt b/Documentation/security/self-protection.txt index 3010576..da8cb36 100644 --- a/Documentation/security/self-protection.txt +++ b/Documentation/security/self-protection.txt @@ -51,7 +51,7 @@ 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 +In support of this are CONFIG_HARDENED_PAGE_MAPPINGS and CONFIG_DEBUG_SET_MODULE_RONX, which seek to make sure that code is not writable, data is not executable, and read-only data is neither writable nor executable. diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 186c4c2..09aff28 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -7,6 +7,7 @@ config ARM select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST select ARCH_HAVE_CUSTOM_GPIO_H select ARCH_HAS_GCOV_PROFILE_ALL + select ARCH_HAS_HARDENED_MAPPINGS if MMU && !XIP_KERNEL select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_USE_BUILTIN_BSWAP diff --git a/arch/arm/configs/aspeed_g4_defconfig b/arch/arm/configs/aspeed_g4_defconfig index ca39c04..8ccc216 100644 --- a/arch/arm/configs/aspeed_g4_defconfig +++ b/arch/arm/configs/aspeed_g4_defconfig @@ -25,7 +25,7 @@ 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_HARDENED_PAGE_MAPPINGS=y CONFIG_AEABI=y CONFIG_UACCESS_WITH_MEMCPY=y CONFIG_SECCOMP=y diff --git a/arch/arm/configs/aspeed_g5_defconfig b/arch/arm/configs/aspeed_g5_defconfig index 4f366b0..90c5ce4 100644 --- a/arch/arm/configs/aspeed_g5_defconfig +++ b/arch/arm/configs/aspeed_g5_defconfig @@ -26,7 +26,7 @@ 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_HARDENED_PAGE_MAPPINGS=y CONFIG_AEABI=y CONFIG_UACCESS_WITH_MEMCPY=y CONFIG_SECCOMP=y diff --git a/arch/arm/include/asm/cacheflush.h b/arch/arm/include/asm/cacheflush.h index bdd283b..c3a7a72 100644 --- a/arch/arm/include/asm/cacheflush.h +++ b/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_HARDENED_PAGE_MAPPINGS void set_kernel_text_rw(void); void set_kernel_text_ro(void); #else diff --git a/arch/arm/kernel/patch.c b/arch/arm/kernel/patch.c index 69bda1a..9da1bf5 100644 --- a/arch/arm/kernel/patch.c +++ b/arch/arm/kernel/patch.c @@ -26,7 +26,7 @@ static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags) if (module && IS_ENABLED(CONFIG_DEBUG_SET_MODULE_RONX)) page = vmalloc_to_page(addr); - else if (!module && IS_ENABLED(CONFIG_DEBUG_RODATA)) + else if (!module && IS_ENABLED(CONFIG_HARDENED_PAGE_MAPPINGS)) page = virt_to_page(addr); else return addr; diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S index f7f55df..5c6a2e8 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -97,7 +97,7 @@ SECTIONS HEAD_TEXT } -#ifdef CONFIG_DEBUG_RODATA +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS . = ALIGN(1<<SECTION_SHIFT); #endif @@ -158,7 +158,7 @@ SECTIONS NOTES -#ifdef CONFIG_DEBUG_RODATA +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS . = 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_HARDENED_PAGE_MAPPINGS . = ALIGN(1<<SECTION_SHIFT); #else . = ALIGN(THREAD_SIZE); @@ -325,7 +325,7 @@ SECTIONS STABS_DEBUG } -#ifdef CONFIG_DEBUG_RODATA +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS /* * Without CONFIG_DEBUG_ALIGN_RODATA, __start_rodata_section_aligned will * be the first section-aligned location after __start_rodata. Otherwise, diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index f68e8ec..e770dc9 100644 --- a/arch/arm/mm/Kconfig +++ b/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 HARDENED_PAGE_MAPPINGS default y help If this is set, rodata will be made explicitly non-executable. This diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c index 370581a..303bee4 100644 --- a/arch/arm/mm/init.c +++ b/arch/arm/mm/init.c @@ -572,7 +572,7 @@ void __init mem_init(void) } } -#ifdef CONFIG_DEBUG_RODATA +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS 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_HARDENED_PAGE_MAPPINGS */ void free_tcmmem(void) { diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 1117421..06fed56 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -11,6 +11,7 @@ config ARM64 select ARCH_HAS_ELF_RANDOMIZE select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_HAS_GIGANTIC_PAGE + select ARCH_HAS_HARDENED_MAPPINGS select ARCH_HAS_KCOV select ARCH_HAS_SG_CHAIN select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST @@ -123,9 +124,6 @@ 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 diff --git a/arch/arm64/Kconfig.debug b/arch/arm64/Kconfig.debug index d1ebd46..a26d27f 100644 --- a/arch/arm64/Kconfig.debug +++ b/arch/arm64/Kconfig.debug @@ -83,7 +83,7 @@ config DEBUG_SET_MODULE_RONX If in doubt, say Y. config DEBUG_ALIGN_RODATA - depends on DEBUG_RODATA + depends on ARCH_HAS_HARDENED_MAPPINGS bool "Align linker sections up to SECTION_SIZE" help If this option is enabled, sections that may potentially be marked as diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig index 3a71f38..7c73eaa 100644 --- a/arch/parisc/Kconfig +++ b/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_HARDENED_MAPPINGS select RTC_CLASS select RTC_DRV_GENERIC select INIT_ALL_POSSIBLE diff --git a/arch/parisc/Kconfig.debug b/arch/parisc/Kconfig.debug index 68b7cbd..0d856b9 100644 --- a/arch/parisc/Kconfig.debug +++ b/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 diff --git a/arch/parisc/configs/712_defconfig b/arch/parisc/configs/712_defconfig index db8f56b..f1a4732 100644 --- a/arch/parisc/configs/712_defconfig +++ b/arch/parisc/configs/712_defconfig @@ -182,7 +182,7 @@ 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_HARDENED_PAGE_MAPPINGS=y CONFIG_CRYPTO_NULL=m CONFIG_CRYPTO_TEST=m CONFIG_CRYPTO_HMAC=y diff --git a/arch/parisc/configs/c3000_defconfig b/arch/parisc/configs/c3000_defconfig index fb92b89..03e88e2 100644 --- a/arch/parisc/configs/c3000_defconfig +++ b/arch/parisc/configs/c3000_defconfig @@ -166,7 +166,7 @@ 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_HARDENED_PAGE_MAPPINGS=y CONFIG_CRYPTO_NULL=m CONFIG_CRYPTO_TEST=m CONFIG_CRYPTO_MD5=m diff --git a/arch/parisc/mm/init.c b/arch/parisc/mm/init.c index e02ada3..f76f8ad 100644 --- a/arch/parisc/mm/init.c +++ b/arch/parisc/mm/init.c @@ -545,7 +545,7 @@ void free_initmem(void) } -#ifdef CONFIG_DEBUG_RODATA +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS void mark_rodata_ro(void) { /* rodata memory was already mapped with KERNEL_RO access rights by diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index c6722112..8e70ae5 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -62,15 +62,13 @@ 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 select ARCH_HAS_ELF_RANDOMIZE select ARCH_HAS_GCOV_PROFILE_ALL select ARCH_HAS_GIGANTIC_PAGE + select ARCH_HAS_HARDENED_MAPPINGS select ARCH_HAS_KCOV select ARCH_HAS_SG_CHAIN select ARCH_HAS_UBSAN_SANITIZE_ALL diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index e487493..9d80cd8 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -50,6 +50,7 @@ config X86 select ARCH_HAS_ELF_RANDOMIZE select ARCH_HAS_FAST_MULTIPLIER select ARCH_HAS_GCOV_PROFILE_ALL + select ARCH_HAS_HARDENED_MAPPINGS select ARCH_HAS_KCOV if X86_64 select ARCH_HAS_MMIO_FLUSH select ARCH_HAS_PMEM_API if X86_64 @@ -309,9 +310,6 @@ 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/include/linux/init.h b/include/linux/init.h index 885c3e6..9967bc9 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -126,10 +126,10 @@ void prepare_namespace(void); void __init load_default_modules(void); int __init init_rootfs(void); -#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX) +#if defined(CONFIG_HARDENED_PAGE_MAPPINGS) || defined(CONFIG_DEBUG_SET_MODULE_RONX) extern bool rodata_enabled; #endif -#ifdef CONFIG_DEBUG_RODATA +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS void mark_rodata_ro(void); #endif diff --git a/init/main.c b/init/main.c index b0c9d6f..4b3bcc4 100644 --- a/init/main.c +++ b/init/main.c @@ -925,7 +925,7 @@ static int try_to_run_init_process(const char *init_filename) static noinline void __init kernel_init_freeable(void); -#if defined(CONFIG_DEBUG_RODATA) || defined(CONFIG_DEBUG_SET_MODULE_RONX) +#if defined(CONFIG_HARDENED_PAGE_MAPPINGS) || defined(CONFIG_DEBUG_SET_MODULE_RONX) bool rodata_enabled __ro_after_init = true; static int __init set_debug_rodata(char *str) { @@ -934,7 +934,7 @@ static int __init set_debug_rodata(char *str) __setup("rodata=", set_debug_rodata); #endif -#ifdef CONFIG_DEBUG_RODATA +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS static void mark_readonly(void) { if (rodata_enabled) diff --git a/kernel/configs/android-recommended.config b/kernel/configs/android-recommended.config index 297756b..b796bc8 100644 --- a/kernel/configs/android-recommended.config +++ b/kernel/configs/android-recommended.config @@ -11,7 +11,7 @@ CONFIG_BLK_DEV_LOOP=y CONFIG_BLK_DEV_RAM=y CONFIG_BLK_DEV_RAM_SIZE=8192 CONFIG_COMPACTION=y -CONFIG_DEBUG_RODATA=y +CONFIG_HARDENED_PAGE_MAPPINGS=y CONFIG_DM_CRYPT=y CONFIG_DM_UEVENT=y CONFIG_DM_VERITY=y diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c index b26dbc4..f7a3ea3 100644 --- a/kernel/power/hibernate.c +++ b/kernel/power/hibernate.c @@ -1156,7 +1156,7 @@ static int __init hibernate_setup(char *str) } else if (!strncmp(str, "no", 2)) { noresume = 1; nohibernate = 1; - } else if (IS_ENABLED(CONFIG_DEBUG_RODATA) + } else if (IS_ENABLED(CONFIG_HARDENED_PAGE_MAPPINGS) && !strncmp(str, "protect_image", 13)) { enable_restore_image_protection(); } diff --git a/kernel/power/power.h b/kernel/power/power.h index 1dfa0da..dc2c7b8 100644 --- a/kernel/power/power.h +++ b/kernel/power/power.h @@ -61,12 +61,12 @@ extern int hibernation_snapshot(int platform_mode); extern int hibernation_restore(int platform_mode); extern int hibernation_platform_enter(void); -#ifdef CONFIG_DEBUG_RODATA +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS /* kernel/power/snapshot.c */ extern void enable_restore_image_protection(void); #else static inline void enable_restore_image_protection(void) {} -#endif /* CONFIG_DEBUG_RODATA */ +#endif /* CONFIG_HARDENED_PAGE_MAPPINGS */ #else /* !CONFIG_HIBERNATION */ diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index 2d8e2b2..a7c793e 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -38,7 +38,7 @@ #include "power.h" -#ifdef CONFIG_DEBUG_RODATA +#ifdef CONFIG_HARDENED_PAGE_MAPPINGS static bool hibernate_restore_protection; static bool hibernate_restore_protection_active; @@ -73,7 +73,7 @@ static inline void hibernate_restore_protection_begin(void) {} static inline void hibernate_restore_protection_end(void) {} static inline void hibernate_restore_protect_page(void *page_address) {} static inline void hibernate_restore_unprotect_page(void *page_address) {} -#endif /* CONFIG_DEBUG_RODATA */ +#endif /* CONFIG_HARDENED_PAGE_MAPPINGS */ static int swsusp_page_is_free(struct page *); static void swsusp_set_page_forbidden(struct page *); diff --git a/security/Kconfig b/security/Kconfig index 118f454..ad6ce82 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -158,6 +158,22 @@ config HARDENED_USERCOPY_PAGESPAN been removed. This config is intended to be used only while trying to find such users. +config ARCH_HAS_HARDENED_MAPPINGS + def_bool n + +config HARDENED_PAGE_MAPPINGS + bool "Mark kernel mappings with stricter permissions (RO/W^X)" + default y + depends on ARCH_HAS_HARDENED_MAPPINGS + 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 attacks (e.g. executing the heap + or modifying text). + + Unless your system has known restrictions or performance issues, it + is recommended to say Y here. + source security/selinux/Kconfig source security/smack/Kconfig source security/tomoyo/Kconfig
Despite the word 'debug' in CONFIG_DEBUG_RODATA, this kernel option provides key security features that are to be expected on a modern system. Change the name to CONFIG_HARDENED_PAGE_MAPPINGS which more accurately describes what this option is intended to do. Signed-off-by: Laura Abbott <labbott@redhat.com> --- Documentation/DocBook/kgdb.tmpl | 8 ++++---- Documentation/security/self-protection.txt | 2 +- arch/arm/Kconfig | 1 + arch/arm/configs/aspeed_g4_defconfig | 2 +- arch/arm/configs/aspeed_g5_defconfig | 2 +- arch/arm/include/asm/cacheflush.h | 2 +- arch/arm/kernel/patch.c | 2 +- arch/arm/kernel/vmlinux.lds.S | 8 ++++---- arch/arm/mm/Kconfig | 14 +------------- arch/arm/mm/init.c | 4 ++-- arch/arm64/Kconfig | 4 +--- arch/arm64/Kconfig.debug | 2 +- arch/parisc/Kconfig | 1 + arch/parisc/Kconfig.debug | 11 ----------- arch/parisc/configs/712_defconfig | 2 +- arch/parisc/configs/c3000_defconfig | 2 +- arch/parisc/mm/init.c | 2 +- arch/s390/Kconfig | 4 +--- arch/x86/Kconfig | 4 +--- include/linux/init.h | 4 ++-- init/main.c | 4 ++-- kernel/configs/android-recommended.config | 2 +- kernel/power/hibernate.c | 2 +- kernel/power/power.h | 4 ++-- kernel/power/snapshot.c | 4 ++-- security/Kconfig | 16 ++++++++++++++++ 26 files changed, 51 insertions(+), 62 deletions(-)