mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
synced 2024-12-28 00:32:00 +00:00
8924560094
Switch from Clang's original forward-edge control-flow integrity implementation to -fsanitize=kcfi, which is better suited for the kernel, as it doesn't require LTO, doesn't use a jump table that requires altering function references, and won't break cross-module function address equality. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Kees Cook <keescook@chromium.org> Tested-by: Kees Cook <keescook@chromium.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20220908215504.3686827-6-samitolvanen@google.com
102 lines
2.2 KiB
C
102 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Clang Control Flow Integrity (CFI) error handling.
|
|
*
|
|
* Copyright (C) 2022 Google LLC
|
|
*/
|
|
|
|
#include <linux/cfi.h>
|
|
|
|
enum bug_trap_type report_cfi_failure(struct pt_regs *regs, unsigned long addr,
|
|
unsigned long *target, u32 type)
|
|
{
|
|
if (target)
|
|
pr_err("CFI failure at %pS (target: %pS; expected type: 0x%08x)\n",
|
|
(void *)addr, (void *)*target, type);
|
|
else
|
|
pr_err("CFI failure at %pS (no target information)\n",
|
|
(void *)addr);
|
|
|
|
if (IS_ENABLED(CONFIG_CFI_PERMISSIVE)) {
|
|
__warn(NULL, 0, (void *)addr, 0, regs, NULL);
|
|
return BUG_TRAP_TYPE_WARN;
|
|
}
|
|
|
|
return BUG_TRAP_TYPE_BUG;
|
|
}
|
|
|
|
#ifdef CONFIG_ARCH_USES_CFI_TRAPS
|
|
static inline unsigned long trap_address(s32 *p)
|
|
{
|
|
return (unsigned long)((long)p + (long)*p);
|
|
}
|
|
|
|
static bool is_trap(unsigned long addr, s32 *start, s32 *end)
|
|
{
|
|
s32 *p;
|
|
|
|
for (p = start; p < end; ++p) {
|
|
if (trap_address(p) == addr)
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
#ifdef CONFIG_MODULES
|
|
/* Populates `kcfi_trap(_end)?` fields in `struct module`. */
|
|
void module_cfi_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
|
|
struct module *mod)
|
|
{
|
|
char *secstrings;
|
|
unsigned int i;
|
|
|
|
mod->kcfi_traps = NULL;
|
|
mod->kcfi_traps_end = NULL;
|
|
|
|
secstrings = (char *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
|
|
|
|
for (i = 1; i < hdr->e_shnum; i++) {
|
|
if (strcmp(secstrings + sechdrs[i].sh_name, "__kcfi_traps"))
|
|
continue;
|
|
|
|
mod->kcfi_traps = (s32 *)sechdrs[i].sh_addr;
|
|
mod->kcfi_traps_end = (s32 *)(sechdrs[i].sh_addr + sechdrs[i].sh_size);
|
|
break;
|
|
}
|
|
}
|
|
|
|
static bool is_module_cfi_trap(unsigned long addr)
|
|
{
|
|
struct module *mod;
|
|
bool found = false;
|
|
|
|
rcu_read_lock_sched_notrace();
|
|
|
|
mod = __module_address(addr);
|
|
if (mod)
|
|
found = is_trap(addr, mod->kcfi_traps, mod->kcfi_traps_end);
|
|
|
|
rcu_read_unlock_sched_notrace();
|
|
|
|
return found;
|
|
}
|
|
#else /* CONFIG_MODULES */
|
|
static inline bool is_module_cfi_trap(unsigned long addr)
|
|
{
|
|
return false;
|
|
}
|
|
#endif /* CONFIG_MODULES */
|
|
|
|
extern s32 __start___kcfi_traps[];
|
|
extern s32 __stop___kcfi_traps[];
|
|
|
|
bool is_cfi_trap(unsigned long addr)
|
|
{
|
|
if (is_trap(addr, __start___kcfi_traps, __stop___kcfi_traps))
|
|
return true;
|
|
|
|
return is_module_cfi_trap(addr);
|
|
}
|
|
#endif /* CONFIG_ARCH_USES_CFI_TRAPS */
|