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Diffstat (limited to 'kernel/static_call.c')
-rw-r--r--kernel/static_call.c60
1 files changed, 58 insertions, 2 deletions
diff --git a/kernel/static_call.c b/kernel/static_call.c
index 84565c2a41b8..6906c6ec4c97 100644
--- a/kernel/static_call.c
+++ b/kernel/static_call.c
@@ -12,6 +12,8 @@
extern struct static_call_site __start_static_call_sites[],
__stop_static_call_sites[];
+extern struct static_call_tramp_key __start_static_call_tramp_key[],
+ __stop_static_call_tramp_key[];
static bool static_call_initialized;
@@ -323,10 +325,59 @@ static int __static_call_mod_text_reserved(void *start, void *end)
return ret;
}
+static unsigned long tramp_key_lookup(unsigned long addr)
+{
+ struct static_call_tramp_key *start = __start_static_call_tramp_key;
+ struct static_call_tramp_key *stop = __stop_static_call_tramp_key;
+ struct static_call_tramp_key *tramp_key;
+
+ for (tramp_key = start; tramp_key != stop; tramp_key++) {
+ unsigned long tramp;
+
+ tramp = (long)tramp_key->tramp + (long)&tramp_key->tramp;
+ if (tramp == addr)
+ return (long)tramp_key->key + (long)&tramp_key->key;
+ }
+
+ return 0;
+}
+
static int static_call_add_module(struct module *mod)
{
- return __static_call_init(mod, mod->static_call_sites,
- mod->static_call_sites + mod->num_static_call_sites);
+ struct static_call_site *start = mod->static_call_sites;
+ struct static_call_site *stop = start + mod->num_static_call_sites;
+ struct static_call_site *site;
+
+ for (site = start; site != stop; site++) {
+ unsigned long addr = (unsigned long)static_call_key(site);
+ unsigned long key;
+
+ /*
+ * Is the key is exported, 'addr' points to the key, which
+ * means modules are allowed to call static_call_update() on
+ * it.
+ *
+ * Otherwise, the key isn't exported, and 'addr' points to the
+ * trampoline so we need to lookup the key.
+ *
+ * We go through this dance to prevent crazy modules from
+ * abusing sensitive static calls.
+ */
+ if (!kernel_text_address(addr))
+ continue;
+
+ key = tramp_key_lookup(addr);
+ if (!key) {
+ pr_warn("Failed to fixup __raw_static_call() usage at: %ps\n",
+ static_call_addr(site));
+ return -EINVAL;
+ }
+
+ site->key = (key - (long)&site->key) |
+ (site->key & STATIC_CALL_SITE_FLAGS);
+ }
+
+ return __static_call_init(mod, start, stop);
}
static void static_call_del_module(struct module *mod)
@@ -438,6 +489,11 @@ int __init static_call_init(void)
}
early_initcall(static_call_init);
+long __static_call_return0(void)
+{
+ return 0;
+}
+
#ifdef CONFIG_STATIC_CALL_SELFTEST
static int func_a(int x)