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101 lines
2.2 KiB
101 lines
2.2 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Clang Control Flow Integrity (CFI) error handling. |
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* |
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* Copyright (C) 2022 Google LLC |
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*/ |
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#include <linux/cfi.h> |
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enum bug_trap_type report_cfi_failure(struct pt_regs *regs, unsigned long addr, |
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unsigned long *target, u32 type) |
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{ |
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if (target) |
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pr_err("CFI failure at %pS (target: %pS; expected type: 0x%08x)\n", |
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(void *)addr, (void *)*target, type); |
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else |
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pr_err("CFI failure at %pS (no target information)\n", |
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(void *)addr); |
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if (IS_ENABLED(CONFIG_CFI_PERMISSIVE)) { |
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__warn(NULL, 0, (void *)addr, 0, regs, NULL); |
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return BUG_TRAP_TYPE_WARN; |
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} |
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return BUG_TRAP_TYPE_BUG; |
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} |
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#ifdef CONFIG_ARCH_USES_CFI_TRAPS |
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static inline unsigned long trap_address(s32 *p) |
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{ |
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return (unsigned long)((long)p + (long)*p); |
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} |
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static bool is_trap(unsigned long addr, s32 *start, s32 *end) |
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{ |
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s32 *p; |
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for (p = start; p < end; ++p) { |
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if (trap_address(p) == addr) |
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return true; |
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} |
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return false; |
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} |
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#ifdef CONFIG_MODULES |
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/* Populates `kcfi_trap(_end)?` fields in `struct module`. */ |
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void module_cfi_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, |
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struct module *mod) |
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{ |
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char *secstrings; |
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unsigned int i; |
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mod->kcfi_traps = NULL; |
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mod->kcfi_traps_end = NULL; |
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secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset; |
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for (i = 1; i < hdr->e_shnum; i++) { |
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if (strcmp(secstrings + sechdrs[i].sh_name, "__kcfi_traps")) |
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continue; |
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mod->kcfi_traps = (s32 *)sechdrs[i].sh_addr; |
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mod->kcfi_traps_end = (s32 *)(sechdrs[i].sh_addr + sechdrs[i].sh_size); |
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break; |
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} |
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} |
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static bool is_module_cfi_trap(unsigned long addr) |
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{ |
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struct module *mod; |
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bool found = false; |
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rcu_read_lock_sched_notrace(); |
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mod = __module_address(addr); |
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if (mod) |
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found = is_trap(addr, mod->kcfi_traps, mod->kcfi_traps_end); |
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rcu_read_unlock_sched_notrace(); |
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return found; |
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} |
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#else /* CONFIG_MODULES */ |
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static inline bool is_module_cfi_trap(unsigned long addr) |
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{ |
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return false; |
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} |
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#endif /* CONFIG_MODULES */ |
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extern s32 __start___kcfi_traps[]; |
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extern s32 __stop___kcfi_traps[]; |
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bool is_cfi_trap(unsigned long addr) |
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{ |
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if (is_trap(addr, __start___kcfi_traps, __stop___kcfi_traps)) |
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return true; |
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return is_module_cfi_trap(addr); |
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} |
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#endif /* CONFIG_ARCH_USES_CFI_TRAPS */
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