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Both of these options are poorly named. The features they provide are necessary for system security and should not be considered debug only. Change the names to CONFIG_STRICT_KERNEL_RWX and CONFIG_STRICT_MODULE_RWX to better describe what these options do. Signed-off-by: Laura Abbott <labbott@redhat.com> Acked-by: Jessica Yu <jeyu@redhat.com> Signed-off-by: Kees Cook <keescook@chromium.org>
129 lines
2.8 KiB
C
129 lines
2.8 KiB
C
#include <linux/kernel.h>
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#include <linux/spinlock.h>
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#include <linux/kprobes.h>
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#include <linux/mm.h>
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#include <linux/stop_machine.h>
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#include <asm/cacheflush.h>
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#include <asm/fixmap.h>
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#include <asm/smp_plat.h>
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#include <asm/opcodes.h>
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#include <asm/patch.h>
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struct patch {
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void *addr;
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unsigned int insn;
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};
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static DEFINE_SPINLOCK(patch_lock);
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static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags)
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__acquires(&patch_lock)
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{
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unsigned int uintaddr = (uintptr_t) addr;
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bool module = !core_kernel_text(uintaddr);
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struct page *page;
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if (module && IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
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page = vmalloc_to_page(addr);
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else if (!module && IS_ENABLED(CONFIG_STRICT_KERNEL_RWX))
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page = virt_to_page(addr);
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else
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return addr;
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if (flags)
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spin_lock_irqsave(&patch_lock, *flags);
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else
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__acquire(&patch_lock);
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set_fixmap(fixmap, page_to_phys(page));
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return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
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}
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static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
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__releases(&patch_lock)
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{
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clear_fixmap(fixmap);
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if (flags)
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spin_unlock_irqrestore(&patch_lock, *flags);
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else
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__release(&patch_lock);
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}
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void __kprobes __patch_text_real(void *addr, unsigned int insn, bool remap)
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{
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bool thumb2 = IS_ENABLED(CONFIG_THUMB2_KERNEL);
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unsigned int uintaddr = (uintptr_t) addr;
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bool twopage = false;
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unsigned long flags;
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void *waddr = addr;
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int size;
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if (remap)
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waddr = patch_map(addr, FIX_TEXT_POKE0, &flags);
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else
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__acquire(&patch_lock);
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if (thumb2 && __opcode_is_thumb16(insn)) {
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*(u16 *)waddr = __opcode_to_mem_thumb16(insn);
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size = sizeof(u16);
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} else if (thumb2 && (uintaddr & 2)) {
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u16 first = __opcode_thumb32_first(insn);
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u16 second = __opcode_thumb32_second(insn);
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u16 *addrh0 = waddr;
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u16 *addrh1 = waddr + 2;
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twopage = (uintaddr & ~PAGE_MASK) == PAGE_SIZE - 2;
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if (twopage && remap)
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addrh1 = patch_map(addr + 2, FIX_TEXT_POKE1, NULL);
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*addrh0 = __opcode_to_mem_thumb16(first);
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*addrh1 = __opcode_to_mem_thumb16(second);
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if (twopage && addrh1 != addr + 2) {
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flush_kernel_vmap_range(addrh1, 2);
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patch_unmap(FIX_TEXT_POKE1, NULL);
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}
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size = sizeof(u32);
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} else {
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if (thumb2)
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insn = __opcode_to_mem_thumb32(insn);
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else
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insn = __opcode_to_mem_arm(insn);
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*(u32 *)waddr = insn;
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size = sizeof(u32);
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}
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if (waddr != addr) {
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flush_kernel_vmap_range(waddr, twopage ? size / 2 : size);
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patch_unmap(FIX_TEXT_POKE0, &flags);
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} else
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__release(&patch_lock);
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flush_icache_range((uintptr_t)(addr),
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(uintptr_t)(addr) + size);
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}
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static int __kprobes patch_text_stop_machine(void *data)
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{
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struct patch *patch = data;
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__patch_text(patch->addr, patch->insn);
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return 0;
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}
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void __kprobes patch_text(void *addr, unsigned int insn)
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{
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struct patch patch = {
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.addr = addr,
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.insn = insn,
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};
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stop_machine(patch_text_stop_machine, &patch, NULL);
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}
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