diff options
Diffstat (limited to 'arch/x86/mm/mmap.c')
-rw-r--r-- | arch/x86/mm/mmap.c | 41 |
1 files changed, 33 insertions, 8 deletions
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c index 155ecbac9e28..db3165714521 100644 --- a/arch/x86/mm/mmap.c +++ b/arch/x86/mm/mmap.c @@ -90,9 +90,10 @@ unsigned long arch_mmap_rnd(void) return arch_rnd(mmap_is_ia32() ? mmap32_rnd_bits : mmap64_rnd_bits); } -static unsigned long mmap_base(unsigned long rnd, unsigned long task_size) +static unsigned long mmap_base(unsigned long rnd, unsigned long task_size, + struct rlimit *rlim_stack) { - unsigned long gap = rlimit(RLIMIT_STACK); + unsigned long gap = rlim_stack->rlim_cur; unsigned long pad = stack_maxrandom_size(task_size) + stack_guard_gap; unsigned long gap_min, gap_max; @@ -126,16 +127,17 @@ static unsigned long mmap_legacy_base(unsigned long rnd, * process VM image, sets up which VM layout function to use: */ static void arch_pick_mmap_base(unsigned long *base, unsigned long *legacy_base, - unsigned long random_factor, unsigned long task_size) + unsigned long random_factor, unsigned long task_size, + struct rlimit *rlim_stack) { *legacy_base = mmap_legacy_base(random_factor, task_size); if (mmap_is_legacy()) *base = *legacy_base; else - *base = mmap_base(random_factor, task_size); + *base = mmap_base(random_factor, task_size, rlim_stack); } -void arch_pick_mmap_layout(struct mm_struct *mm) +void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack) { if (mmap_is_legacy()) mm->get_unmapped_area = arch_get_unmapped_area; @@ -143,7 +145,8 @@ void arch_pick_mmap_layout(struct mm_struct *mm) mm->get_unmapped_area = arch_get_unmapped_area_topdown; arch_pick_mmap_base(&mm->mmap_base, &mm->mmap_legacy_base, - arch_rnd(mmap64_rnd_bits), task_size_64bit(0)); + arch_rnd(mmap64_rnd_bits), task_size_64bit(0), + rlim_stack); #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES /* @@ -153,7 +156,8 @@ void arch_pick_mmap_layout(struct mm_struct *mm) * mmap_base, the compat syscall uses mmap_compat_base. */ arch_pick_mmap_base(&mm->mmap_compat_base, &mm->mmap_compat_legacy_base, - arch_rnd(mmap32_rnd_bits), task_size_32bit()); + arch_rnd(mmap32_rnd_bits), task_size_32bit(), + rlim_stack); #endif } @@ -162,7 +166,7 @@ unsigned long get_mmap_base(int is_legacy) struct mm_struct *mm = current->mm; #ifdef CONFIG_HAVE_ARCH_COMPAT_MMAP_BASES - if (in_compat_syscall()) { + if (in_32bit_syscall()) { return is_legacy ? mm->mmap_compat_legacy_base : mm->mmap_compat_base; } @@ -236,3 +240,24 @@ int valid_mmap_phys_addr_range(unsigned long pfn, size_t count) return phys_addr_valid(addr + count - 1); } + +/* + * Only allow root to set high MMIO mappings to PROT_NONE. + * This prevents an unpriv. user to set them to PROT_NONE and invert + * them, then pointing to valid memory for L1TF speculation. + * + * Note: for locked down kernels may want to disable the root override. + */ +bool pfn_modify_allowed(unsigned long pfn, pgprot_t prot) +{ + if (!boot_cpu_has_bug(X86_BUG_L1TF)) + return true; + if (!__pte_needs_invert(pgprot_val(prot))) + return true; + /* If it's real memory always allow */ + if (pfn_valid(pfn)) + return true; + if (pfn >= l1tf_pfn_limit() && !capable(CAP_SYS_ADMIN)) + return false; + return true; +} |