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bpf: Add dummy BPF STRUCT_OPS for test purpose
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@huawei.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20211025064025.2567443-4-houtao1@huawei.com
This commit is contained in:
parent
35346ab641
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c196906d50
@ -1018,6 +1018,22 @@ static inline void bpf_module_put(const void *data, struct module *owner)
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else
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module_put(owner);
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}
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#ifdef CONFIG_NET
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/* Define it here to avoid the use of forward declaration */
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struct bpf_dummy_ops_state {
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int val;
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};
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struct bpf_dummy_ops {
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int (*test_1)(struct bpf_dummy_ops_state *cb);
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int (*test_2)(struct bpf_dummy_ops_state *cb, int a1, unsigned short a2,
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char a3, unsigned long a4);
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};
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int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
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union bpf_attr __user *uattr);
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#endif
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#else
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static inline const struct bpf_struct_ops *bpf_struct_ops_find(u32 type_id)
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{
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@ -93,6 +93,9 @@ const struct bpf_verifier_ops bpf_struct_ops_verifier_ops = {
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};
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const struct bpf_prog_ops bpf_struct_ops_prog_ops = {
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#ifdef CONFIG_NET
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.test_run = bpf_struct_ops_test_run,
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#endif
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};
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static const struct btf_type *module_type;
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@ -2,6 +2,9 @@
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/* internal file - do not include directly */
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#ifdef CONFIG_BPF_JIT
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#ifdef CONFIG_NET
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BPF_STRUCT_OPS_TYPE(bpf_dummy_ops)
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#endif
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#ifdef CONFIG_INET
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#include <net/tcp.h>
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BPF_STRUCT_OPS_TYPE(tcp_congestion_ops)
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@ -1,2 +1,5 @@
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# SPDX-License-Identifier: GPL-2.0-only
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obj-$(CONFIG_BPF_SYSCALL) := test_run.o
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ifeq ($(CONFIG_BPF_JIT),y)
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obj-$(CONFIG_BPF_SYSCALL) += bpf_dummy_struct_ops.o
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endif
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200
net/bpf/bpf_dummy_struct_ops.c
Normal file
200
net/bpf/bpf_dummy_struct_ops.c
Normal file
@ -0,0 +1,200 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 2021. Huawei Technologies Co., Ltd
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*/
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#include <linux/kernel.h>
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#include <linux/bpf_verifier.h>
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#include <linux/bpf.h>
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#include <linux/btf.h>
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extern struct bpf_struct_ops bpf_bpf_dummy_ops;
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/* A common type for test_N with return value in bpf_dummy_ops */
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typedef int (*dummy_ops_test_ret_fn)(struct bpf_dummy_ops_state *state, ...);
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struct bpf_dummy_ops_test_args {
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u64 args[MAX_BPF_FUNC_ARGS];
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struct bpf_dummy_ops_state state;
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};
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static struct bpf_dummy_ops_test_args *
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dummy_ops_init_args(const union bpf_attr *kattr, unsigned int nr)
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{
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__u32 size_in;
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struct bpf_dummy_ops_test_args *args;
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void __user *ctx_in;
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void __user *u_state;
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size_in = kattr->test.ctx_size_in;
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if (size_in != sizeof(u64) * nr)
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return ERR_PTR(-EINVAL);
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args = kzalloc(sizeof(*args), GFP_KERNEL);
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if (!args)
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return ERR_PTR(-ENOMEM);
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ctx_in = u64_to_user_ptr(kattr->test.ctx_in);
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if (copy_from_user(args->args, ctx_in, size_in))
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goto out;
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/* args[0] is 0 means state argument of test_N will be NULL */
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u_state = u64_to_user_ptr(args->args[0]);
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if (u_state && copy_from_user(&args->state, u_state,
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sizeof(args->state)))
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goto out;
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return args;
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out:
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kfree(args);
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return ERR_PTR(-EFAULT);
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}
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static int dummy_ops_copy_args(struct bpf_dummy_ops_test_args *args)
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{
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void __user *u_state;
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u_state = u64_to_user_ptr(args->args[0]);
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if (u_state && copy_to_user(u_state, &args->state, sizeof(args->state)))
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return -EFAULT;
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return 0;
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}
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static int dummy_ops_call_op(void *image, struct bpf_dummy_ops_test_args *args)
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{
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dummy_ops_test_ret_fn test = (void *)image;
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struct bpf_dummy_ops_state *state = NULL;
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/* state needs to be NULL if args[0] is 0 */
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if (args->args[0])
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state = &args->state;
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return test(state, args->args[1], args->args[2],
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args->args[3], args->args[4]);
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}
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int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr,
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union bpf_attr __user *uattr)
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{
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const struct bpf_struct_ops *st_ops = &bpf_bpf_dummy_ops;
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const struct btf_type *func_proto;
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struct bpf_dummy_ops_test_args *args;
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struct bpf_tramp_progs *tprogs;
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void *image = NULL;
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unsigned int op_idx;
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int prog_ret;
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int err;
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if (prog->aux->attach_btf_id != st_ops->type_id)
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return -EOPNOTSUPP;
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func_proto = prog->aux->attach_func_proto;
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args = dummy_ops_init_args(kattr, btf_type_vlen(func_proto));
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if (IS_ERR(args))
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return PTR_ERR(args);
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tprogs = kcalloc(BPF_TRAMP_MAX, sizeof(*tprogs), GFP_KERNEL);
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if (!tprogs) {
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err = -ENOMEM;
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goto out;
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}
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image = bpf_jit_alloc_exec(PAGE_SIZE);
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if (!image) {
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err = -ENOMEM;
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goto out;
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}
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set_vm_flush_reset_perms(image);
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op_idx = prog->expected_attach_type;
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err = bpf_struct_ops_prepare_trampoline(tprogs, prog,
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&st_ops->func_models[op_idx],
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image, image + PAGE_SIZE);
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if (err < 0)
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goto out;
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set_memory_ro((long)image, 1);
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set_memory_x((long)image, 1);
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prog_ret = dummy_ops_call_op(image, args);
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err = dummy_ops_copy_args(args);
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if (err)
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goto out;
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if (put_user(prog_ret, &uattr->test.retval))
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err = -EFAULT;
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out:
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kfree(args);
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bpf_jit_free_exec(image);
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kfree(tprogs);
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return err;
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}
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static int bpf_dummy_init(struct btf *btf)
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{
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return 0;
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}
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static bool bpf_dummy_ops_is_valid_access(int off, int size,
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enum bpf_access_type type,
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const struct bpf_prog *prog,
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struct bpf_insn_access_aux *info)
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{
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return bpf_tracing_btf_ctx_access(off, size, type, prog, info);
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}
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static int bpf_dummy_ops_btf_struct_access(struct bpf_verifier_log *log,
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const struct btf *btf,
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const struct btf_type *t, int off,
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int size, enum bpf_access_type atype,
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u32 *next_btf_id)
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{
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const struct btf_type *state;
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s32 type_id;
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int err;
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type_id = btf_find_by_name_kind(btf, "bpf_dummy_ops_state",
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BTF_KIND_STRUCT);
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if (type_id < 0)
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return -EINVAL;
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state = btf_type_by_id(btf, type_id);
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if (t != state) {
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bpf_log(log, "only access to bpf_dummy_ops_state is supported\n");
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return -EACCES;
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}
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err = btf_struct_access(log, btf, t, off, size, atype, next_btf_id);
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if (err < 0)
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return err;
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return atype == BPF_READ ? err : NOT_INIT;
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}
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static const struct bpf_verifier_ops bpf_dummy_verifier_ops = {
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.is_valid_access = bpf_dummy_ops_is_valid_access,
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.btf_struct_access = bpf_dummy_ops_btf_struct_access,
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};
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static int bpf_dummy_init_member(const struct btf_type *t,
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const struct btf_member *member,
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void *kdata, const void *udata)
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{
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return -EOPNOTSUPP;
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}
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static int bpf_dummy_reg(void *kdata)
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{
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return -EOPNOTSUPP;
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}
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static void bpf_dummy_unreg(void *kdata)
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{
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}
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struct bpf_struct_ops bpf_bpf_dummy_ops = {
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.verifier_ops = &bpf_dummy_verifier_ops,
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.init = bpf_dummy_init,
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.init_member = bpf_dummy_init_member,
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.reg = bpf_dummy_reg,
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.unreg = bpf_dummy_unreg,
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.name = "bpf_dummy_ops",
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};
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