| Message ID | 20190526134746.9315-14-alex@ghiti.fr (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Provide generic top-down mmap layout functions | expand |
On Sun, May 26, 2019 at 09:47:45AM -0400, Alexandre Ghiti wrote: > mips uses a top-down layout by default that exactly fits the generic > functions, so get rid of arch specific code and use the generic version > by selecting ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT. > As ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT selects ARCH_HAS_ELF_RANDOMIZE, > use the generic version of arch_randomize_brk since it also fits. > Note that this commit also removes the possibility for mips to have elf > randomization and no MMU: without MMU, the security added by randomization > is worth nothing. > > Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> Reviewed-by: Kees Cook <keescook@chromium.org> -Kees > --- > arch/mips/Kconfig | 2 +- > arch/mips/include/asm/processor.h | 5 -- > arch/mips/mm/mmap.c | 96 ------------------------------- > 3 files changed, 1 insertion(+), 102 deletions(-) > > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig > index 70d3200476bf..da15b02bbe23 100644 > --- a/arch/mips/Kconfig > +++ b/arch/mips/Kconfig > @@ -5,7 +5,6 @@ config MIPS > select ARCH_32BIT_OFF_T if !64BIT > select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT > select ARCH_CLOCKSOURCE_DATA > - select ARCH_HAS_ELF_RANDOMIZE > select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST > select ARCH_HAS_UBSAN_SANITIZE_ALL > select ARCH_SUPPORTS_UPROBES > @@ -13,6 +12,7 @@ config MIPS > select ARCH_USE_CMPXCHG_LOCKREF if 64BIT > select ARCH_USE_QUEUED_RWLOCKS > select ARCH_USE_QUEUED_SPINLOCKS > + select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU > select ARCH_WANT_IPC_PARSE_VERSION > select BUILDTIME_EXTABLE_SORT > select CLONE_BACKWARDS > diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h > index aca909bd7841..fba18d4a9190 100644 > --- a/arch/mips/include/asm/processor.h > +++ b/arch/mips/include/asm/processor.h > @@ -29,11 +29,6 @@ > > extern unsigned int vced_count, vcei_count; > > -/* > - * MIPS does have an arch_pick_mmap_layout() > - */ > -#define HAVE_ARCH_PICK_MMAP_LAYOUT 1 > - > #ifdef CONFIG_32BIT > #ifdef CONFIG_KVM_GUEST > /* User space process size is limited to 1GB in KVM Guest Mode */ > diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c > index 900670ea8531..c2effe535484 100644 > --- a/arch/mips/mm/mmap.c > +++ b/arch/mips/mm/mmap.c > @@ -16,49 +16,10 @@ > #include <linux/random.h> > #include <linux/sched/signal.h> > #include <linux/sched/mm.h> > -#include <linux/sizes.h> > -#include <linux/compat.h> > > unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */ > EXPORT_SYMBOL(shm_align_mask); > > -/* gap between mmap and stack */ > -#define MIN_GAP (128*1024*1024UL) > -#define MAX_GAP ((STACK_TOP)/6*5) > -#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) > - > -static int mmap_is_legacy(struct rlimit *rlim_stack) > -{ > - if (current->personality & ADDR_COMPAT_LAYOUT) > - return 1; > - > - if (rlim_stack->rlim_cur == RLIM_INFINITY) > - return 1; > - > - return sysctl_legacy_va_layout; > -} > - > -static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) > -{ > - unsigned long gap = rlim_stack->rlim_cur; > - unsigned long pad = stack_guard_gap; > - > - /* Account for stack randomization if necessary */ > - if (current->flags & PF_RANDOMIZE) > - pad += (STACK_RND_MASK << PAGE_SHIFT); > - > - /* Values close to RLIM_INFINITY can overflow. */ > - if (gap + pad > gap) > - gap += pad; > - > - if (gap < MIN_GAP) > - gap = MIN_GAP; > - else if (gap > MAX_GAP) > - gap = MAX_GAP; > - > - return PAGE_ALIGN(STACK_TOP - gap - rnd); > -} > - > #define COLOUR_ALIGN(addr, pgoff) \ > ((((addr) + shm_align_mask) & ~shm_align_mask) + \ > (((pgoff) << PAGE_SHIFT) & shm_align_mask)) > @@ -156,63 +117,6 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp, > addr0, len, pgoff, flags, DOWN); > } > > -unsigned long arch_mmap_rnd(void) > -{ > - unsigned long rnd; > - > -#ifdef CONFIG_COMPAT > - if (TASK_IS_32BIT_ADDR) > - rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); > - else > -#endif /* CONFIG_COMPAT */ > - rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); > - > - return rnd << PAGE_SHIFT; > -} > - > -void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) > -{ > - unsigned long random_factor = 0UL; > - > - if (current->flags & PF_RANDOMIZE) > - random_factor = arch_mmap_rnd(); > - > - if (mmap_is_legacy(rlim_stack)) { > - mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; > - mm->get_unmapped_area = arch_get_unmapped_area; > - } else { > - mm->mmap_base = mmap_base(random_factor, rlim_stack); > - mm->get_unmapped_area = arch_get_unmapped_area_topdown; > - } > -} > - > -static inline unsigned long brk_rnd(void) > -{ > - unsigned long rnd = get_random_long(); > - > - rnd = rnd << PAGE_SHIFT; > - /* 32MB for 32bit, 1GB for 64bit */ > - if (!IS_ENABLED(CONFIG_64BIT) || is_compat_task()) > - rnd = rnd & SZ_32M; > - else > - rnd = rnd & SZ_1G; > - > - return rnd; > -} > - > -unsigned long arch_randomize_brk(struct mm_struct *mm) > -{ > - unsigned long base = mm->brk; > - unsigned long ret; > - > - ret = PAGE_ALIGN(base + brk_rnd()); > - > - if (ret < mm->brk) > - return mm->brk; > - > - return ret; > -} > - > int __virt_addr_valid(const volatile void *kaddr) > { > return pfn_valid(PFN_DOWN(virt_to_phys(kaddr))); > -- > 2.20.1 >
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 70d3200476bf..da15b02bbe23 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -5,7 +5,6 @@ config MIPS select ARCH_32BIT_OFF_T if !64BIT select ARCH_BINFMT_ELF_STATE if MIPS_FP_SUPPORT select ARCH_CLOCKSOURCE_DATA - select ARCH_HAS_ELF_RANDOMIZE select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST select ARCH_HAS_UBSAN_SANITIZE_ALL select ARCH_SUPPORTS_UPROBES @@ -13,6 +12,7 @@ config MIPS select ARCH_USE_CMPXCHG_LOCKREF if 64BIT select ARCH_USE_QUEUED_RWLOCKS select ARCH_USE_QUEUED_SPINLOCKS + select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU select ARCH_WANT_IPC_PARSE_VERSION select BUILDTIME_EXTABLE_SORT select CLONE_BACKWARDS diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h index aca909bd7841..fba18d4a9190 100644 --- a/arch/mips/include/asm/processor.h +++ b/arch/mips/include/asm/processor.h @@ -29,11 +29,6 @@ extern unsigned int vced_count, vcei_count; -/* - * MIPS does have an arch_pick_mmap_layout() - */ -#define HAVE_ARCH_PICK_MMAP_LAYOUT 1 - #ifdef CONFIG_32BIT #ifdef CONFIG_KVM_GUEST /* User space process size is limited to 1GB in KVM Guest Mode */ diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c index 900670ea8531..c2effe535484 100644 --- a/arch/mips/mm/mmap.c +++ b/arch/mips/mm/mmap.c @@ -16,49 +16,10 @@ #include <linux/random.h> #include <linux/sched/signal.h> #include <linux/sched/mm.h> -#include <linux/sizes.h> -#include <linux/compat.h> unsigned long shm_align_mask = PAGE_SIZE - 1; /* Sane caches */ EXPORT_SYMBOL(shm_align_mask); -/* gap between mmap and stack */ -#define MIN_GAP (128*1024*1024UL) -#define MAX_GAP ((STACK_TOP)/6*5) -#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) - -static int mmap_is_legacy(struct rlimit *rlim_stack) -{ - if (current->personality & ADDR_COMPAT_LAYOUT) - return 1; - - if (rlim_stack->rlim_cur == RLIM_INFINITY) - return 1; - - return sysctl_legacy_va_layout; -} - -static unsigned long mmap_base(unsigned long rnd, struct rlimit *rlim_stack) -{ - unsigned long gap = rlim_stack->rlim_cur; - unsigned long pad = stack_guard_gap; - - /* Account for stack randomization if necessary */ - if (current->flags & PF_RANDOMIZE) - pad += (STACK_RND_MASK << PAGE_SHIFT); - - /* Values close to RLIM_INFINITY can overflow. */ - if (gap + pad > gap) - gap += pad; - - if (gap < MIN_GAP) - gap = MIN_GAP; - else if (gap > MAX_GAP) - gap = MAX_GAP; - - return PAGE_ALIGN(STACK_TOP - gap - rnd); -} - #define COLOUR_ALIGN(addr, pgoff) \ ((((addr) + shm_align_mask) & ~shm_align_mask) + \ (((pgoff) << PAGE_SHIFT) & shm_align_mask)) @@ -156,63 +117,6 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp, addr0, len, pgoff, flags, DOWN); } -unsigned long arch_mmap_rnd(void) -{ - unsigned long rnd; - -#ifdef CONFIG_COMPAT - if (TASK_IS_32BIT_ADDR) - rnd = get_random_long() & ((1UL << mmap_rnd_compat_bits) - 1); - else -#endif /* CONFIG_COMPAT */ - rnd = get_random_long() & ((1UL << mmap_rnd_bits) - 1); - - return rnd << PAGE_SHIFT; -} - -void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) -{ - unsigned long random_factor = 0UL; - - if (current->flags & PF_RANDOMIZE) - random_factor = arch_mmap_rnd(); - - if (mmap_is_legacy(rlim_stack)) { - mm->mmap_base = TASK_UNMAPPED_BASE + random_factor; - mm->get_unmapped_area = arch_get_unmapped_area; - } else { - mm->mmap_base = mmap_base(random_factor, rlim_stack); - mm->get_unmapped_area = arch_get_unmapped_area_topdown; - } -} - -static inline unsigned long brk_rnd(void) -{ - unsigned long rnd = get_random_long(); - - rnd = rnd << PAGE_SHIFT; - /* 32MB for 32bit, 1GB for 64bit */ - if (!IS_ENABLED(CONFIG_64BIT) || is_compat_task()) - rnd = rnd & SZ_32M; - else - rnd = rnd & SZ_1G; - - return rnd; -} - -unsigned long arch_randomize_brk(struct mm_struct *mm) -{ - unsigned long base = mm->brk; - unsigned long ret; - - ret = PAGE_ALIGN(base + brk_rnd()); - - if (ret < mm->brk) - return mm->brk; - - return ret; -} - int __virt_addr_valid(const volatile void *kaddr) { return pfn_valid(PFN_DOWN(virt_to_phys(kaddr)));
mips uses a top-down layout by default that exactly fits the generic functions, so get rid of arch specific code and use the generic version by selecting ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT. As ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT selects ARCH_HAS_ELF_RANDOMIZE, use the generic version of arch_randomize_brk since it also fits. Note that this commit also removes the possibility for mips to have elf randomization and no MMU: without MMU, the security added by randomization is worth nothing. Signed-off-by: Alexandre Ghiti <alex@ghiti.fr> --- arch/mips/Kconfig | 2 +- arch/mips/include/asm/processor.h | 5 -- arch/mips/mm/mmap.c | 96 ------------------------------- 3 files changed, 1 insertion(+), 102 deletions(-)