mips: extract logic for mmap_rnd()
In preparation for splitting out ET_DYN ASLR, extract the mmap ASLR selection into a separate function. Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Ingo Molnar <mingo@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -142,18 +142,26 @@ unsigned long arch_get_unmapped_area_topdown(struct file *filp,
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addr0, len, pgoff, flags, DOWN);
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}
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static unsigned long mmap_rnd(void)
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{
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unsigned long rnd;
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rnd = (unsigned long)get_random_int();
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rnd <<= PAGE_SHIFT;
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if (TASK_IS_32BIT_ADDR)
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rnd &= 0xfffffful;
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else
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rnd &= 0xffffffful;
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return rnd;
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}
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void arch_pick_mmap_layout(struct mm_struct *mm)
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{
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unsigned long random_factor = 0UL;
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if (current->flags & PF_RANDOMIZE) {
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random_factor = get_random_int();
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random_factor = random_factor << PAGE_SHIFT;
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if (TASK_IS_32BIT_ADDR)
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random_factor &= 0xfffffful;
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else
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random_factor &= 0xffffffful;
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}
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if (current->flags & PF_RANDOMIZE)
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random_factor = mmap_rnd();
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if (mmap_is_legacy()) {
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mm->mmap_base = TASK_UNMAPPED_BASE + random_factor;
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