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authorSami Tolvanen <samitolvanen@google.com>2022-09-08 14:54:47 -0700
committerKees Cook <keescook@chromium.org>2022-09-26 10:13:13 -0700
commit89245600941e4e0f87d77f60ee269b5e61ef4e49 (patch)
treea0069b5bd625907cb854091e6dbbeed4964815b0 /kernel/module
parent92efda8eb15295a07f450828b2db14485bfc09c2 (diff)
cfi: Switch to -fsanitize=kcfi
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
Diffstat (limited to 'kernel/module')
-rw-r--r--kernel/module/main.c35
1 files changed, 3 insertions, 32 deletions
diff --git a/kernel/module/main.c b/kernel/module/main.c
index 0228f44b58e5..70c0b2c6fef8 100644
--- a/kernel/module/main.c
+++ b/kernel/module/main.c
@@ -53,6 +53,7 @@
#include <linux/bsearch.h>
#include <linux/dynamic_debug.h>
#include <linux/audit.h>
+#include <linux/cfi.h>
#include <uapi/linux/module.h>
#include "internal.h"
@@ -2597,8 +2598,9 @@ static int complete_formation(struct module *mod, struct load_info *info)
if (err < 0)
goto out;
- /* This relies on module_mutex for list integrity. */
+ /* These rely on module_mutex for list integrity. */
module_bug_finalize(info->hdr, info->sechdrs, mod);
+ module_cfi_finalize(info->hdr, info->sechdrs, mod);
if (module_check_misalignment(mod))
goto out_misaligned;
@@ -2660,8 +2662,6 @@ static int unknown_module_param_cb(char *param, char *val, const char *modname,
return 0;
}
-static void cfi_init(struct module *mod);
-
/*
* Allocate and load the module: note that size of section 0 is always
* zero, and we rely on this for optional sections.
@@ -2791,9 +2791,6 @@ static int load_module(struct load_info *info, const char __user *uargs,
flush_module_icache(mod);
- /* Setup CFI for the module. */
- cfi_init(mod);
-
/* Now copy in args */
mod->args = strndup_user(uargs, ~0UL >> 1);
if (IS_ERR(mod->args)) {
@@ -2955,32 +2952,6 @@ static inline int within(unsigned long addr, void *start, unsigned long size)
return ((void *)addr >= start && (void *)addr < start + size);
}
-static void cfi_init(struct module *mod)
-{
-#ifdef CONFIG_CFI_CLANG
- initcall_t *init;
-#ifdef CONFIG_MODULE_UNLOAD
- exitcall_t *exit;
-#endif
-
- rcu_read_lock_sched();
- mod->cfi_check = (cfi_check_fn)
- find_kallsyms_symbol_value(mod, "__cfi_check");
- init = (initcall_t *)
- find_kallsyms_symbol_value(mod, "__cfi_jt_init_module");
- /* Fix init/exit functions to point to the CFI jump table */
- if (init)
- mod->init = *init;
-#ifdef CONFIG_MODULE_UNLOAD
- exit = (exitcall_t *)
- find_kallsyms_symbol_value(mod, "__cfi_jt_cleanup_module");
- if (exit)
- mod->exit = *exit;
-#endif
- rcu_read_unlock_sched();
-#endif
-}
-
/* Keep in sync with MODULE_FLAGS_BUF_SIZE !!! */
char *module_flags(struct module *mod, char *buf, bool show_state)
{