Merge "do not rely on ALLOW_ERROR_INJECTION for fmod_ret" into bpf-next

Merge commit 5b481aca ("bpf: do not rely on ALLOW_ERROR_INJECTION for fmod_ret")
from hid tree into bpf-next.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

include/linux/btf.h

@@ -478,8 +478,10 @@ struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog);
 u32 *btf_kfunc_id_set_contains(const struct btf *btf,
 			       enum bpf_prog_type prog_type,
 			       u32 kfunc_btf_id);
+u32 *btf_kfunc_is_modify_return(const struct btf *btf, u32 kfunc_btf_id);
 int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
 			      const struct btf_kfunc_id_set *s);
+int register_btf_fmodret_id_set(const struct btf_kfunc_id_set *kset);
 s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id);
 int register_btf_id_dtor_kfuncs(const struct btf_id_dtor_kfunc *dtors, u32 add_cnt,
 				struct module *owner);

kernel/bpf/btf.c

@@ -206,6 +206,7 @@ enum btf_kfunc_hook {
 	BTF_KFUNC_HOOK_STRUCT_OPS,
 	BTF_KFUNC_HOOK_TRACING,
 	BTF_KFUNC_HOOK_SYSCALL,
+	BTF_KFUNC_HOOK_FMODRET,
 	BTF_KFUNC_HOOK_MAX,
 };
 
@@ -7608,11 +7609,14 @@ u32 *btf_kfunc_id_set_contains(const struct btf *btf,
 	return __btf_kfunc_id_set_contains(btf, hook, kfunc_btf_id);
 }
 
-/* This function must be invoked only from initcalls/module init functions */
-int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
+u32 *btf_kfunc_is_modify_return(const struct btf *btf, u32 kfunc_btf_id)
+{
+	return __btf_kfunc_id_set_contains(btf, BTF_KFUNC_HOOK_FMODRET, kfunc_btf_id);
+}
+
+static int __register_btf_kfunc_id_set(enum btf_kfunc_hook hook,
 				       const struct btf_kfunc_id_set *kset)
 {
-	enum btf_kfunc_hook hook;
 	struct btf *btf;
 	int ret;
 
@@ -7631,13 +7635,29 @@ int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
 	if (IS_ERR(btf))
 		return PTR_ERR(btf);
 
-	hook = bpf_prog_type_to_kfunc_hook(prog_type);
 	ret = btf_populate_kfunc_set(btf, hook, kset->set);
 	btf_put(btf);
 	return ret;
 }
+
+/* This function must be invoked only from initcalls/module init functions */
+int register_btf_kfunc_id_set(enum bpf_prog_type prog_type,
+			      const struct btf_kfunc_id_set *kset)
+{
+	enum btf_kfunc_hook hook;
+
+	hook = bpf_prog_type_to_kfunc_hook(prog_type);
+	return __register_btf_kfunc_id_set(hook, kset);
+}
 EXPORT_SYMBOL_GPL(register_btf_kfunc_id_set);
 
+/* This function must be invoked only from initcalls/module init functions */
+int register_btf_fmodret_id_set(const struct btf_kfunc_id_set *kset)
+{
+	return __register_btf_kfunc_id_set(BTF_KFUNC_HOOK_FMODRET, kset);
+}
+EXPORT_SYMBOL_GPL(register_btf_fmodret_id_set);
+
 s32 btf_find_dtor_kfunc(struct btf *btf, u32 btf_id)
 {
 	struct btf_id_dtor_kfunc_tab *tab = btf->dtor_kfunc_tab;

kernel/bpf/verifier.c

@@ -16519,12 +16519,22 @@ int bpf_check_attach_target(struct bpf_verifier_log *log,
 			ret = -EINVAL;
 			switch (prog->type) {
 			case BPF_PROG_TYPE_TRACING:
-				/* fentry/fexit/fmod_ret progs can be sleepable only if they are
+
+				/* fentry/fexit/fmod_ret progs can be sleepable if they are
 				 * attached to ALLOW_ERROR_INJECTION and are not in denylist.
 				 */
 				if (!check_non_sleepable_error_inject(btf_id) &&
 				    within_error_injection_list(addr))
 					ret = 0;
+				/* fentry/fexit/fmod_ret progs can also be sleepable if they are
+				 * in the fmodret id set with the KF_SLEEPABLE flag.
+				 */
+				else {
+					u32 *flags = btf_kfunc_is_modify_return(btf, btf_id);
+
+					if (flags && (*flags & KF_SLEEPABLE))
+						ret = 0;
+				}
 				break;
 			case BPF_PROG_TYPE_LSM:
 				/* LSM progs check that they are attached to bpf_lsm_*() funcs.
@@ -16545,7 +16555,10 @@ int bpf_check_attach_target(struct bpf_verifier_log *log,
 				bpf_log(log, "can't modify return codes of BPF programs\n");
 				return -EINVAL;
 			}
-			ret = check_attach_modify_return(addr, tname);
+			ret = -EINVAL;
+			if (btf_kfunc_is_modify_return(btf, btf_id) ||
+			    !check_attach_modify_return(addr, tname))
+				ret = 0;
 			if (ret) {
 				bpf_log(log, "%s() is not modifiable\n", tname);
 				return ret;

net/bpf/test_run.c

@@ -489,7 +489,6 @@ int noinline bpf_fentry_test1(int a)
 	return a + 1;
 }
 EXPORT_SYMBOL_GPL(bpf_fentry_test1);
-ALLOW_ERROR_INJECTION(bpf_fentry_test1, ERRNO);
 
 int noinline bpf_fentry_test2(int a, u64 b)
 {
@@ -733,7 +732,15 @@ noinline void bpf_kfunc_call_test_destructive(void)
 
 __diag_pop();
 
-ALLOW_ERROR_INJECTION(bpf_modify_return_test, ERRNO);
+BTF_SET8_START(bpf_test_modify_return_ids)
+BTF_ID_FLAGS(func, bpf_modify_return_test)
+BTF_ID_FLAGS(func, bpf_fentry_test1, KF_SLEEPABLE)
+BTF_SET8_END(bpf_test_modify_return_ids)
+
+static const struct btf_kfunc_id_set bpf_test_modify_return_set = {
+	.owner = THIS_MODULE,
+	.set   = &bpf_test_modify_return_ids,
+};
 
 BTF_SET8_START(test_sk_check_kfunc_ids)
 BTF_ID_FLAGS(func, bpf_kfunc_call_test1)
@@ -1666,7 +1673,8 @@ static int __init bpf_prog_test_run_init(void)
 	};
 	int ret;
 
-	ret = register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_prog_test_kfunc_set);
+	ret = register_btf_fmodret_id_set(&bpf_test_modify_return_set);
+	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_prog_test_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_prog_test_kfunc_set);
 	ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &bpf_prog_test_kfunc_set);
 	return ret ?: register_btf_id_dtor_kfuncs(bpf_prog_test_dtor_kfunc,