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Merge branch 'introduce dummy BPF STRUCT_OPS'
Hou Tao says:
====================
Hi,
Currently the test of BPF STRUCT_OPS depends on the specific bpf
implementation (e.g, 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.
Instead of loading a userspace-implemeted bpf_dummy_ops map into
kernel and calling the specific function by writing to sysfs provided
by bpf_testmode.ko, only loading bpf_dummy_ops related prog into
kernel and calling these prog by bpf_prog_test_run(). The latter
is more flexible and has no dependency on extra kernel module.
Now the return value handling is supported by test_1(...) ops,
and passing multiple arguments is supported by test_2(...) ops.
If more is needed, test_x(...) ops can be added afterwards.
Comments are always welcome.
Regards,
Hou
Change Log:
v4:
* add Acked-by tags in patch 1~4
* patch 2: remove unncessary comments and update commit message
accordingly
* patch 4: remove unnecessary nr checking in dummy_ops_init_args()
v3: https://www.spinics.net/lists/bpf/msg48303.html
* rebase on bpf-next
* address comments for Martin, mainly include: merge patch 3 &
patch 4 in v2, fix names of btf ctx access check helpers,
handle CONFIG_NET, fix leak in dummy_ops_init_args(), and
simplify bpf_dummy_init()
* patch 4: use a loop to check args in test_dummy_multiple_args()
v2: https://www.spinics.net/lists/bpf/msg47948.html
* rebase on bpf-next
* add test_2(...) ops to test the passing of multiple arguments
* a new patch (patch #2) is added to factor out ctx access helpers
* address comments from Martin & Andrii
v1: https://www.spinics.net/lists/bpf/msg46787.html
RFC: https://www.spinics.net/lists/bpf/msg46117.html
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -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 |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,200 @@ | ||
| // 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; | ||
|
|
||
| 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", | ||
| }; |
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