Currently the test of BPF STRUCT_OPS depends on the specific bpf
implementation of tcp_congestion_ops, but it can not cover all
basic functionalities (e.g, return value handling), so introduce
a dummy BPF STRUCT_OPS for test purpose.
Loading a bpf_dummy_ops implementation from userspace is prohibited,
and its only purpose is to run BPF_PROG_TYPE_STRUCT_OPS program
through bpf(BPF_PROG_TEST_RUN). Now programs for test_1() & test_2()
are supported. The following three cases are exercised in
bpf_dummy_struct_ops_test_run():
(1) test and check the value returned from state arg in test_1(state)
The content of state is copied from userspace pointer and copied back
after calling test_1(state). The user pointer is saved in an u64 array
and the array address is passed through ctx_in.
(2) test and check the return value of test_1(NULL)
Just simulate the case in which an invalid input argument is passed in.
(3) test multiple arguments passing in test_2(state, ...)
5 arguments are passed through ctx_in in form of u64 array. The first
element of array is userspace pointer of state and others 4 arguments
follow.
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
---
include/linux/bpf.h | 16 +++
kernel/bpf/bpf_struct_ops.c | 3 +
kernel/bpf/bpf_struct_ops_types.h | 3 +
net/bpf/Makefile | 3 +
net/bpf/bpf_dummy_struct_ops.c | 203 ++++++++++++++++++++++++++++++
5 files changed, 228 insertions(+)
create mode 100644 net/bpf/bpf_dummy_struct_ops.c
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 0dd2de9eeed3..1297af15ec1c 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1017,6 +1017,22 @@ static inline void bpf_module_put(const void *data, struct module *owner)
else
module_put(owner);
}
+
+#ifdef CONFIG_NET
+/* Define it here to avoid the use of forward declaration */
+struct bpf_dummy_ops_state {
+ int val;
+};
+
+struct bpf_dummy_ops {
+ int (*test_1)(struct bpf_dummy_ops_state *cb);
+ int (*test_2)(struct bpf_dummy_ops_state *cb, int a1, unsigned short a2,
+ char a3, unsigned long a4);
+};
+
+int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
+ union bpf_attr __user *uattr);
+#endif
#else
static inline const struct bpf_struct_ops *bpf_struct_ops_find(u32 type_id)
{
diff --git a/kernel/bpf/bpf_struct_ops.c b/kernel/bpf/bpf_struct_ops.c
index 44be101f2562..8ecfe4752769 100644
--- a/kernel/bpf/bpf_struct_ops.c
+++ b/kernel/bpf/bpf_struct_ops.c
@@ -93,6 +93,9 @@ const struct bpf_verifier_ops bpf_struct_ops_verifier_ops = {
};
const struct bpf_prog_ops bpf_struct_ops_prog_ops = {
+#ifdef CONFIG_NET
+ .test_run = bpf_struct_ops_test_run,
+#endif
};
static const struct btf_type *module_type;
diff --git a/kernel/bpf/bpf_struct_ops_types.h b/kernel/bpf/bpf_struct_ops_types.h
index 066d83ea1c99..5678a9ddf817 100644
--- a/kernel/bpf/bpf_struct_ops_types.h
+++ b/kernel/bpf/bpf_struct_ops_types.h
@@ -2,6 +2,9 @@
/* internal file - do not include directly */
#ifdef CONFIG_BPF_JIT
+#ifdef CONFIG_NET
+BPF_STRUCT_OPS_TYPE(bpf_dummy_ops)
+#endif
#ifdef CONFIG_INET
#include <net/tcp.h>
BPF_STRUCT_OPS_TYPE(tcp_congestion_ops)
diff --git a/net/bpf/Makefile b/net/bpf/Makefile
index 1c0a98d8c28f..1ebe270bde23 100644
--- a/net/bpf/Makefile
+++ b/net/bpf/Makefile
@@ -1,2 +1,5 @@
# SPDX-License-Identifier: GPL-2.0-only
obj-$(CONFIG_BPF_SYSCALL) := test_run.o
+ifeq ($(CONFIG_BPF_JIT),y)
+obj-$(CONFIG_BPF_SYSCALL) += bpf_dummy_struct_ops.o
+endif
diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c
new file mode 100644
index 000000000000..ac27836e55df
--- /dev/null
+++ b/net/bpf/bpf_dummy_struct_ops.c
@@ -0,0 +1,203 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021. Huawei Technologies Co., Ltd
+ */
+#include <linux/kernel.h>
+#include <linux/bpf_verifier.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+
+extern struct bpf_struct_ops bpf_bpf_dummy_ops;
+
+/* A common type for test_N with return value in bpf_dummy_ops */
+typedef int (*dummy_ops_test_ret_fn)(struct bpf_dummy_ops_state *state, ...);
+
+struct bpf_dummy_ops_test_args {
+ u64 args[MAX_BPF_FUNC_ARGS];
+ struct bpf_dummy_ops_state state;
+};
+
+static struct bpf_dummy_ops_test_args *
+dummy_ops_init_args(const union bpf_attr *kattr, unsigned int nr)
+{
+ __u32 size_in;
+ struct bpf_dummy_ops_test_args *args;
+ void __user *ctx_in;
+ void __user *u_state;
+
+ if (!nr || nr > MAX_BPF_FUNC_ARGS)
+ return ERR_PTR(-EINVAL);
+
+ size_in = kattr->test.ctx_size_in;
+ if (size_in != sizeof(u64) * nr)
+ return ERR_PTR(-EINVAL);
+
+ args = kzalloc(sizeof(*args), GFP_KERNEL);
+ if (!args)
+ return ERR_PTR(-ENOMEM);
+
+ ctx_in = u64_to_user_ptr(kattr->test.ctx_in);
+ if (copy_from_user(args->args, ctx_in, size_in))
+ goto out;
+
+ /* args[0] is 0 means state argument of test_N will be NULL */
+ u_state = u64_to_user_ptr(args->args[0]);
+ if (u_state && copy_from_user(&args->state, u_state,
+ sizeof(args->state)))
+ goto out;
+
+ return args;
+out:
+ kfree(args);
+ return ERR_PTR(-EFAULT);
+}
+
+static int dummy_ops_copy_args(struct bpf_dummy_ops_test_args *args)
+{
+ void __user *u_state;
+
+ u_state = u64_to_user_ptr(args->args[0]);
+ if (u_state && copy_to_user(u_state, &args->state, sizeof(args->state)))
+ return -EFAULT;
+
+ return 0;
+}
+
+static int dummy_ops_call_op(void *image, struct bpf_dummy_ops_test_args *args)
+{
+ dummy_ops_test_ret_fn test = (void *)image;
+ struct bpf_dummy_ops_state *state = NULL;
+
+ /* state needs to be NULL if args[0] is 0 */
+ if (args->args[0])
+ state = &args->state;
+ return test(state, args->args[1], args->args[2],
+ args->args[3], args->args[4]);
+}
+
+int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
+ union bpf_attr __user *uattr)
+{
+ const struct bpf_struct_ops *st_ops = &bpf_bpf_dummy_ops;
+ const struct btf_type *func_proto;
+ struct bpf_dummy_ops_test_args *args;
+ struct bpf_tramp_progs *tprogs;
+ void *image = NULL;
+ unsigned int op_idx;
+ int prog_ret;
+ int err;
+
+ if (prog->aux->attach_btf_id != st_ops->type_id)
+ return -EOPNOTSUPP;
+
+ func_proto = prog->aux->attach_func_proto;
+ args = dummy_ops_init_args(kattr, btf_type_vlen(func_proto));
+ if (IS_ERR(args))
+ return PTR_ERR(args);
+
+ tprogs = kcalloc(BPF_TRAMP_MAX, sizeof(*tprogs), GFP_KERNEL);
+ if (!tprogs) {
+ err = -ENOMEM;
+ goto out;
+ }
+
+ image = bpf_jit_alloc_exec(PAGE_SIZE);
+ if (!image) {
+ err = -ENOMEM;
+ goto out;
+ }
+ set_vm_flush_reset_perms(image);
+
+ op_idx = prog->expected_attach_type;
+ err = bpf_struct_ops_prepare_trampoline(tprogs, prog,
+ &st_ops->func_models[op_idx],
+ image, image + PAGE_SIZE);
+ if (err < 0)
+ goto out;
+
+ set_memory_ro((long)image, 1);
+ set_memory_x((long)image, 1);
+ prog_ret = dummy_ops_call_op(image, args);
+
+ err = dummy_ops_copy_args(args);
+ if (err)
+ goto out;
+ if (put_user(prog_ret, &uattr->test.retval))
+ err = -EFAULT;
+out:
+ kfree(args);
+ bpf_jit_free_exec(image);
+ kfree(tprogs);
+ return err;
+}
+
+static int bpf_dummy_init(struct btf *btf)
+{
+ return 0;
+}
+
+static bool bpf_dummy_ops_is_valid_access(int off, int size,
+ enum bpf_access_type type,
+ const struct bpf_prog *prog,
+ struct bpf_insn_access_aux *info)
+{
+ return bpf_tracing_btf_ctx_access(off, size, type, prog, info);
+}
+
+static int bpf_dummy_ops_btf_struct_access(struct bpf_verifier_log *log,
+ const struct btf *btf,
+ const struct btf_type *t, int off,
+ int size, enum bpf_access_type atype,
+ u32 *next_btf_id)
+{
+ const struct btf_type *state;
+ s32 type_id;
+ int err;
+
+ type_id = btf_find_by_name_kind(btf, "bpf_dummy_ops_state",
+ BTF_KIND_STRUCT);
+ if (type_id < 0)
+ return -EINVAL;
+
+ state = btf_type_by_id(btf, type_id);
+ if (t != state) {
+ bpf_log(log, "only access to bpf_dummy_ops_state is supported\n");
+ return -EACCES;
+ }
+
+ err = btf_struct_access(log, btf, t, off, size, atype, next_btf_id);
+ if (err < 0)
+ return err;
+
+ return atype == BPF_READ ? err : NOT_INIT;
+}
+
+static const struct bpf_verifier_ops bpf_dummy_verifier_ops = {
+ .is_valid_access = bpf_dummy_ops_is_valid_access,
+ .btf_struct_access = bpf_dummy_ops_btf_struct_access,
+};
+
+static int bpf_dummy_init_member(const struct btf_type *t,
+ const struct btf_member *member,
+ void *kdata, const void *udata)
+{
+ return -EOPNOTSUPP;
+}
+
+static int bpf_dummy_reg(void *kdata)
+{
+ return -EOPNOTSUPP;
+}
+
+static void bpf_dummy_unreg(void *kdata)
+{
+}
+
+struct bpf_struct_ops bpf_bpf_dummy_ops = {
+ .verifier_ops = &bpf_dummy_verifier_ops,
+ .init = bpf_dummy_init,
+ .init_member = bpf_dummy_init_member,
+ .reg = bpf_dummy_reg,
+ .unreg = bpf_dummy_unreg,
+ .name = "bpf_dummy_ops",
+};
--
2.29.2
