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Commit 4a86220e authored by Benjamin Tissoires's avatar Benjamin Tissoires
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HID: bpf: remove tracing HID-BPF capability 

We can now rely on struct_ops as we cleared the users in-tree.

Link: https://lore.kernel.org/r/20240608-hid_bpf_struct_ops-v3-8-6ac6ade58329@kernel.orgSigned-off-by: default avatarBenjamin Tissoires <bentiss@kernel.org>
parent 50fe0fc6
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Showing with 8 additions and 1187 deletions
drivers/hid/bpf/Makefile
View file @ 4a86220e
......@@ -8,4 +8,4 @@ LIBBPF_INCLUDE = $(srctree)/tools/lib
obj-$(CONFIG_HID_BPF) += hid_bpf.o
CFLAGS_hid_bpf_dispatch.o += -I$(LIBBPF_INCLUDE)
CFLAGS_hid_bpf_jmp_table.o += -I$(LIBBPF_INCLUDE)
hid_bpf-objs += hid_bpf_dispatch.o hid_bpf_jmp_table.o hid_bpf_struct_ops.o
hid_bpf-objs += hid_bpf_dispatch.o hid_bpf_struct_ops.o
drivers/hid/bpf/entrypoints/Makefile deleted 100644 → 0
View file @ 50fe0fc6
# SPDX-License-Identifier: GPL-2.0
OUTPUT := .output
abs_out := $(abspath $(OUTPUT))
CLANG ?= clang
LLC ?= llc
LLVM_STRIP ?= llvm-strip
TOOLS_PATH := $(abspath ../../../../tools)
BPFTOOL_SRC := $(TOOLS_PATH)/bpf/bpftool
BPFTOOL_OUTPUT := $(abs_out)/bpftool
DEFAULT_BPFTOOL := $(BPFTOOL_OUTPUT)/bootstrap/bpftool
BPFTOOL ?= $(DEFAULT_BPFTOOL)
LIBBPF_SRC := $(TOOLS_PATH)/lib/bpf
LIBBPF_OUTPUT := $(abs_out)/libbpf
LIBBPF_DESTDIR := $(LIBBPF_OUTPUT)
LIBBPF_INCLUDE := $(LIBBPF_DESTDIR)/include
BPFOBJ := $(LIBBPF_OUTPUT)/libbpf.a
INCLUDES := -I$(OUTPUT) -I$(LIBBPF_INCLUDE) -I$(TOOLS_PATH)/include/uapi
CFLAGS := -g -Wall
VMLINUX_BTF_PATHS ?= $(if $(O),$(O)/vmlinux) \
$(if $(KBUILD_OUTPUT),$(KBUILD_OUTPUT)/vmlinux) \
../../../../vmlinux \
/sys/kernel/btf/vmlinux \
/boot/vmlinux-$(shell uname -r)
VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))
ifeq ($(VMLINUX_BTF),)
$(error Cannot find a vmlinux for VMLINUX_BTF at any of "$(VMLINUX_BTF_PATHS)")
endif
ifeq ($(V),1)
Q =
msg =
else
Q = @
msg = @printf ' %-8s %s%s\n' "$(1)" "$(notdir $(2))" "$(if $(3), $(3))";
MAKEFLAGS += --no-print-directory
submake_extras := feature_display=0
endif
.DELETE_ON_ERROR:
.PHONY: all clean
all: entrypoints.lskel.h
clean:
$(call msg,CLEAN)
$(Q)rm -rf $(OUTPUT) entrypoints
entrypoints.lskel.h: $(OUTPUT)/entrypoints.bpf.o | $(BPFTOOL)
$(call msg,GEN-SKEL,$@)
$(Q)$(BPFTOOL) gen skeleton -L $< > $@
$(OUTPUT)/entrypoints.bpf.o: entrypoints.bpf.c $(OUTPUT)/vmlinux.h $(BPFOBJ) | $(OUTPUT)
$(call msg,BPF,$@)
$(Q)$(CLANG) -g -O2 --target=bpf $(INCLUDES) \
-c $(filter %.c,$^) -o $@ && \
$(LLVM_STRIP) -g $@
$(OUTPUT)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL) | $(INCLUDE_DIR)
ifeq ($(VMLINUX_H),)
$(call msg,GEN,,$@)
$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
else
$(call msg,CP,,$@)
$(Q)cp "$(VMLINUX_H)" $@
endif
$(OUTPUT) $(LIBBPF_OUTPUT) $(BPFTOOL_OUTPUT):
$(call msg,MKDIR,$@)
$(Q)mkdir -p $@
$(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OUTPUT)
$(Q)$(MAKE) $(submake_extras) -C $(LIBBPF_SRC) \
OUTPUT=$(abspath $(dir $@))/ prefix= \
DESTDIR=$(LIBBPF_DESTDIR) $(abspath $@) install_headers
ifeq ($(CROSS_COMPILE),)
$(DEFAULT_BPFTOOL): $(BPFOBJ) | $(BPFTOOL_OUTPUT)
$(Q)$(MAKE) $(submake_extras) -C $(BPFTOOL_SRC) \
OUTPUT=$(BPFTOOL_OUTPUT)/ \
LIBBPF_BOOTSTRAP_OUTPUT=$(LIBBPF_OUTPUT)/ \
LIBBPF_BOOTSTRAP_DESTDIR=$(LIBBPF_DESTDIR)/ bootstrap
else
$(DEFAULT_BPFTOOL): | $(BPFTOOL_OUTPUT)
$(Q)$(MAKE) $(submake_extras) -C $(BPFTOOL_SRC) \
OUTPUT=$(BPFTOOL_OUTPUT)/ bootstrap
endif
drivers/hid/bpf/entrypoints/README deleted 100644 → 0
View file @ 50fe0fc6
WARNING:
If you change "entrypoints.bpf.c" do "make -j" in this directory to rebuild "entrypoints.skel.h".
Make sure to have clang 10 installed.
See Documentation/bpf/bpf_devel_QA.rst
drivers/hid/bpf/entrypoints/entrypoints.bpf.c deleted 100644 → 0
View file @ 50fe0fc6
// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2022 Benjamin Tissoires */
#include ".output/vmlinux.h"
#include <bpf/bpf_helpers.h>
#include <bpf/bpf_tracing.h>
#define HID_BPF_MAX_PROGS 1024
struct {
__uint(type, BPF_MAP_TYPE_PROG_ARRAY);
__uint(max_entries, HID_BPF_MAX_PROGS);
__uint(key_size, sizeof(__u32));
__uint(value_size, sizeof(__u32));
} hid_jmp_table SEC(".maps");
SEC("fmod_ret/__hid_bpf_tail_call")
int BPF_PROG(hid_tail_call, struct hid_bpf_ctx *hctx)
{
bpf_tail_call(ctx, &hid_jmp_table, hctx->index);
return 0;
}
char LICENSE[] SEC("license") = "GPL";
drivers/hid/bpf/entrypoints/entrypoints.lskel.h deleted 100644 → 0
View file @ 50fe0fc6
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
/* THIS FILE IS AUTOGENERATED BY BPFTOOL! */
#ifndef __ENTRYPOINTS_BPF_SKEL_H__
#define __ENTRYPOINTS_BPF_SKEL_H__
#include <bpf/skel_internal.h>
struct entrypoints_bpf {
struct bpf_loader_ctx ctx;
struct {
struct bpf_map_desc hid_jmp_table;
} maps;
struct {
struct bpf_prog_desc hid_tail_call;
} progs;
struct {
int hid_tail_call_fd;
} links;
};
static inline int
entrypoints_bpf__hid_tail_call__attach(struct entrypoints_bpf *skel)
{
int prog_fd = skel->progs.hid_tail_call.prog_fd;
int fd = skel_raw_tracepoint_open(NULL, prog_fd);
if (fd > 0)
skel->links.hid_tail_call_fd = fd;
return fd;
}
static inline int
entrypoints_bpf__attach(struct entrypoints_bpf *skel)
{
int ret = 0;
ret = ret < 0 ? ret : entrypoints_bpf__hid_tail_call__attach(skel);
return ret < 0 ? ret : 0;
}
static inline void
entrypoints_bpf__detach(struct entrypoints_bpf *skel)
{
skel_closenz(skel->links.hid_tail_call_fd);
}
static void
entrypoints_bpf__destroy(struct entrypoints_bpf *skel)
{
if (!skel)
return;
entrypoints_bpf__detach(skel);
skel_closenz(skel->progs.hid_tail_call.prog_fd);
skel_closenz(skel->maps.hid_jmp_table.map_fd);
skel_free(skel);
}
static inline struct entrypoints_bpf *
entrypoints_bpf__open(void)
{
struct entrypoints_bpf *skel;
skel = skel_alloc(sizeof(*skel));
if (!skel)
goto cleanup;
skel->ctx.sz = (void *)&skel->links - (void *)skel;
return skel;
cleanup:
entrypoints_bpf__destroy(skel);
return NULL;
}
static inline int
entrypoints_bpf__load(struct entrypoints_bpf *skel)
{
struct bpf_load_and_run_opts opts = {};
int err;
opts.ctx = (struct bpf_loader_ctx *)skel;
opts.data_sz = 2856;
opts.data = (void *)"\
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\0\0";
opts.insns_sz = 1192;
opts.insns = (void *)"\
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\0\0\xb7\0\0\0\0\0\0\0\x95\0\0\0\0\0\0\0";
err = bpf_load_and_run(&opts);
if (err < 0)
return err;
return 0;
}
static inline struct entrypoints_bpf *
entrypoints_bpf__open_and_load(void)
{
struct entrypoints_bpf *skel;
skel = entrypoints_bpf__open();
if (!skel)
return NULL;
if (entrypoints_bpf__load(skel)) {
entrypoints_bpf__destroy(skel);
return NULL;
}
return skel;
}
__attribute__((unused)) static void
entrypoints_bpf__assert(struct entrypoints_bpf *s __attribute__((unused)))
{
#ifdef __cplusplus
#define _Static_assert static_assert
#endif
#ifdef __cplusplus
#undef _Static_assert
#endif
}
#endif /* __ENTRYPOINTS_BPF_SKEL_H__ */
drivers/hid/bpf/hid_bpf_dispatch.c
View file @ 4a86220e
......@@ -3,7 +3,7 @@
/*
* HID-BPF support for Linux
*
* Copyright (c) 2022 Benjamin Tissoires
* Copyright (c) 2022-2024 Benjamin Tissoires
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
......@@ -17,34 +17,11 @@
#include <linux/kfifo.h>
#include <linux/minmax.h>
#include <linux/module.h>
#include <linux/workqueue.h>
#include "hid_bpf_dispatch.h"
#include "entrypoints/entrypoints.lskel.h"
struct hid_ops *hid_ops;
EXPORT_SYMBOL(hid_ops);
/**
* hid_bpf_device_event - Called whenever an event is coming in from the device
*
* @ctx: The HID-BPF context
*
* @return %0 on success and keep processing; a positive value to change the
* incoming size buffer; a negative error code to interrupt the processing
* of this event
*
* Declare an %fmod_ret tracing bpf program to this function and attach this
* program through hid_bpf_attach_prog() to have this helper called for
* any incoming event from the device itself.
*
* The function is called while on IRQ context, so we can not sleep.
*/
/* never used by the kernel but declared so we can load and attach a tracepoint */
__weak noinline int hid_bpf_device_event(struct hid_bpf_ctx *ctx)
{
return 0;
}
u8 *
dispatch_hid_bpf_device_event(struct hid_device *hdev, enum hid_report_type type, u8 *data,
u32 *size, int interrupt)
......@@ -52,7 +29,6 @@ dispatch_hid_bpf_device_event(struct hid_device *hdev, enum hid_report_type type
struct hid_bpf_ctx_kern ctx_kern = {
.ctx = {
.hid = hdev,
.report_type = type,
.allocated_size = hdev->bpf.allocated_data,
.size = *size,
},
......@@ -86,11 +62,6 @@ dispatch_hid_bpf_device_event(struct hid_device *hdev, enum hid_report_type type
}
rcu_read_unlock();
ret = hid_bpf_prog_run(hdev, HID_BPF_PROG_TYPE_DEVICE_EVENT, &ctx_kern);
if (ret < 0)
return ERR_PTR(ret);
ret = ctx_kern.ctx.retval;
if (ret) {
if (ret > ctx_kern.ctx.allocated_size)
return ERR_PTR(-EINVAL);
......@@ -102,26 +73,6 @@ dispatch_hid_bpf_device_event(struct hid_device *hdev, enum hid_report_type type
}
EXPORT_SYMBOL_GPL(dispatch_hid_bpf_device_event);
/**
* hid_bpf_rdesc_fixup - Called when the probe function parses the report
* descriptor of the HID device
*
* @ctx: The HID-BPF context
*
* @return 0 on success and keep processing; a positive value to change the
* incoming size buffer; a negative error code to interrupt the processing
* of this event
*
* Declare an %fmod_ret tracing bpf program to this function and attach this
* program through hid_bpf_attach_prog() to have this helper called before any
* parsing of the report descriptor by HID.
*/
/* never used by the kernel but declared so we can load and attach a tracepoint */
__weak noinline int hid_bpf_rdesc_fixup(struct hid_bpf_ctx *ctx)
{
return 0;
}
u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size)
{
int ret;
......@@ -133,16 +84,16 @@ u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *s
},
};
if (!hdev->bpf.rdesc_ops)
goto ignore_bpf;
ctx_kern.data = kzalloc(ctx_kern.ctx.allocated_size, GFP_KERNEL);
if (!ctx_kern.data)
goto ignore_bpf;
memcpy(ctx_kern.data, rdesc, min_t(unsigned int, *size, HID_MAX_DESCRIPTOR_SIZE));
if (hdev->bpf.rdesc_ops)
ret = hdev->bpf.rdesc_ops->hid_rdesc_fixup(&ctx_kern.ctx);
else
ret = hid_bpf_prog_run(hdev, HID_BPF_PROG_TYPE_RDESC_FIXUP, &ctx_kern);
if (ret < 0)
goto ignore_bpf;
......@@ -242,39 +193,6 @@ int hid_bpf_reconnect(struct hid_device *hdev)
return 0;
}
static int do_hid_bpf_attach_prog(struct hid_device *hdev, int prog_fd, struct bpf_prog *prog,
__u32 flags)
{
int fd, err, prog_type;
prog_type = hid_bpf_get_prog_attach_type(prog);
if (prog_type < 0)
return prog_type;
if (prog_type >= HID_BPF_PROG_TYPE_MAX)
return -EINVAL;
if (prog_type == HID_BPF_PROG_TYPE_DEVICE_EVENT) {
err = hid_bpf_allocate_event_data(hdev);
if (err)
return err;
}
fd = __hid_bpf_attach_prog(hdev, prog_type, prog_fd, prog, flags);
if (fd < 0)
return fd;
if (prog_type == HID_BPF_PROG_TYPE_RDESC_FIXUP) {
err = hid_bpf_reconnect(hdev);
if (err) {
close_fd(fd);
return err;
}
}
return fd;
}
/* Disables missing prototype warnings */
__bpf_kfunc_start_defs();
......@@ -303,57 +221,6 @@ hid_bpf_get_data(struct hid_bpf_ctx *ctx, unsigned int offset, const size_t rdwr
return ctx_kern->data + offset;
}
/**
* hid_bpf_attach_prog - Attach the given @prog_fd to the given HID device
*
* @hid_id: the system unique identifier of the HID device
* @prog_fd: an fd in the user process representing the program to attach
* @flags: any logical OR combination of &enum hid_bpf_attach_flags
*
* @returns an fd of a bpf_link object on success (> %0), an error code otherwise.
* Closing this fd will detach the program from the HID device (unless the bpf_link
* is pinned to the BPF file system).
*/
/* called from syscall */
__bpf_kfunc int
hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, __u32 flags)
{
struct hid_device *hdev;
struct bpf_prog *prog;
int err, fd;
if ((flags & ~HID_BPF_FLAG_MASK))
return -EINVAL;
hdev = hid_get_device(hid_id);
if (IS_ERR(hdev))
return PTR_ERR(hdev);
/*
* take a ref on the prog itself, it will be released
* on errors or when it'll be detached
*/
prog = bpf_prog_get(prog_fd);
if (IS_ERR(prog)) {
err = PTR_ERR(prog);
goto out_dev_put;
}
fd = do_hid_bpf_attach_prog(hdev, prog_fd, prog, flags);
if (fd < 0) {
err = fd;
goto out_prog_put;
}
return fd;
out_prog_put:
bpf_prog_put(prog);
out_dev_put:
hid_put_device(hdev);
return err;
}
/**
* hid_bpf_allocate_context - Allocate a context to the given HID device
*
......@@ -583,21 +450,8 @@ static const struct btf_kfunc_id_set hid_bpf_kfunc_set = {
.set = &hid_bpf_kfunc_ids,
};
/* our HID-BPF entrypoints */
BTF_SET8_START(hid_bpf_fmodret_ids)
BTF_ID_FLAGS(func, hid_bpf_device_event)
BTF_ID_FLAGS(func, hid_bpf_rdesc_fixup)
BTF_ID_FLAGS(func, __hid_bpf_tail_call)
BTF_SET8_END(hid_bpf_fmodret_ids)
static const struct btf_kfunc_id_set hid_bpf_fmodret_set = {
.owner = THIS_MODULE,
.set = &hid_bpf_fmodret_ids,
};
/* for syscall HID-BPF */
BTF_KFUNCS_START(hid_bpf_syscall_kfunc_ids)
BTF_ID_FLAGS(func, hid_bpf_attach_prog)
BTF_ID_FLAGS(func, hid_bpf_allocate_context, KF_ACQUIRE | KF_RET_NULL)
BTF_ID_FLAGS(func, hid_bpf_release_context, KF_RELEASE)
BTF_ID_FLAGS(func, hid_bpf_hw_request)
......@@ -622,8 +476,6 @@ int hid_bpf_connect_device(struct hid_device *hdev)
break;
}
}
if (rcu_dereference(hdev->bpf.progs[HID_BPF_PROG_TYPE_DEVICE_EVENT]))
need_to_allocate = true;
rcu_read_unlock();
/* only allocate BPF data if there are programs attached */
......@@ -650,14 +502,12 @@ void hid_bpf_destroy_device(struct hid_device *hdev)
/* mark the device as destroyed in bpf so we don't reattach it */
hdev->bpf.destroyed = true;
__hid_bpf_destroy_device(hdev);
__hid_bpf_ops_destroy_device(hdev);
}
EXPORT_SYMBOL_GPL(hid_bpf_destroy_device);
void hid_bpf_device_init(struct hid_device *hdev)
{
spin_lock_init(&hdev->bpf.progs_lock);
INIT_LIST_HEAD(&hdev->bpf.prog_list);
mutex_init(&hdev->bpf.prog_list_lock);
}
......@@ -670,37 +520,15 @@ static int __init hid_bpf_init(void)
/* Note: if we exit with an error any time here, we would entirely break HID, which
* is probably not something we want. So we log an error and return success.
*
* This is not a big deal: the syscall allowing to attach a BPF program to a HID device
* will not be available, so nobody will be able to use the functionality.
* This is not a big deal: nobody will be able to use the functionality.
*/
err = register_btf_fmodret_id_set(&hid_bpf_fmodret_set);
if (err) {
pr_warn("error while registering fmodret entrypoints: %d", err);
return 0;
}
err = hid_bpf_preload_skel();
if (err) {
pr_warn("error while preloading HID BPF dispatcher: %d", err);
return 0;
}
/* register tracing kfuncs after we are sure we can load our preloaded bpf program */
err = register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &hid_bpf_kfunc_set);
if (err) {
pr_warn("error while setting HID BPF tracing kfuncs: %d", err);
return 0;
}
/* register struct_ops kfuncs after we are sure we can load our preloaded bpf program */
err = register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &hid_bpf_kfunc_set);
if (err) {
pr_warn("error while setting HID BPF tracing kfuncs: %d", err);
return 0;
}
/* register syscalls after we are sure we can load our preloaded bpf program */
err = register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &hid_bpf_syscall_kfunc_set);
if (err) {
pr_warn("error while setting HID BPF syscall kfuncs: %d", err);
......@@ -710,15 +538,6 @@ static int __init hid_bpf_init(void)
return 0;
}
static void __exit hid_bpf_exit(void)
{
/* HID depends on us, so if we hit that code, we are guaranteed that hid
* has been removed and thus we do not need to clear the HID devices
*/
hid_bpf_free_links_and_skel();
}
late_initcall(hid_bpf_init);
module_exit(hid_bpf_exit);
MODULE_AUTHOR("Benjamin Tissoires");
MODULE_LICENSE("GPL");
drivers/hid/bpf/hid_bpf_dispatch.h
View file @ 4a86220e
......@@ -13,15 +13,7 @@ struct hid_bpf_ctx_kern {
struct hid_device *hid_get_device(unsigned int hid_id);
void hid_put_device(struct hid_device *hid);
int hid_bpf_allocate_event_data(struct hid_device *hdev);
int hid_bpf_preload_skel(void);
void hid_bpf_free_links_and_skel(void);
int hid_bpf_get_prog_attach_type(struct bpf_prog *prog);
int __hid_bpf_attach_prog(struct hid_device *hdev, enum hid_bpf_prog_type prog_type, int prog_fd,
struct bpf_prog *prog, __u32 flags);
void __hid_bpf_destroy_device(struct hid_device *hdev);
void __hid_bpf_ops_destroy_device(struct hid_device *hdev);
int hid_bpf_prog_run(struct hid_device *hdev, enum hid_bpf_prog_type type,
struct hid_bpf_ctx_kern *ctx_kern);
int hid_bpf_reconnect(struct hid_device *hdev);
struct bpf_prog;
......
drivers/hid/bpf/hid_bpf_jmp_table.c deleted 100644 → 0
View file @ 50fe0fc6
// SPDX-License-Identifier: GPL-2.0-only
/*
* HID-BPF support for Linux
*
* Copyright (c) 2022 Benjamin Tissoires
*/
#include <linux/bitops.h>
#include <linux/btf.h>
#include <linux/btf_ids.h>
#include <linux/circ_buf.h>
#include <linux/filter.h>
#include <linux/hid.h>
#include <linux/hid_bpf.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/workqueue.h>
#include "hid_bpf_dispatch.h"
#include "entrypoints/entrypoints.lskel.h"
#define HID_BPF_MAX_PROGS 1024 /* keep this in sync with preloaded bpf,
* needs to be a power of 2 as we use it as
* a circular buffer
*/
#define NEXT(idx) (((idx) + 1) & (HID_BPF_MAX_PROGS - 1))
#define PREV(idx) (((idx) - 1) & (HID_BPF_MAX_PROGS - 1))
/*
* represents one attached program stored in the hid jump table
*/
struct hid_bpf_prog_entry {
struct bpf_prog *prog;
struct hid_device *hdev;
enum hid_bpf_prog_type type;
u16 idx;
};
struct hid_bpf_jmp_table {
struct bpf_map *map;
struct hid_bpf_prog_entry entries[HID_BPF_MAX_PROGS]; /* compacted list, circular buffer */
int tail, head;
struct bpf_prog *progs[HID_BPF_MAX_PROGS]; /* idx -> progs mapping */
unsigned long enabled[BITS_TO_LONGS(HID_BPF_MAX_PROGS)];
};
#define FOR_ENTRIES(__i, __start, __end) \
for (__i = __start; CIRC_CNT(__end, __i, HID_BPF_MAX_PROGS); __i = NEXT(__i))
static struct hid_bpf_jmp_table jmp_table;
static DEFINE_MUTEX(hid_bpf_attach_lock); /* held when attaching/detaching programs */
static void hid_bpf_release_progs(struct work_struct *work);
static DECLARE_WORK(release_work, hid_bpf_release_progs);
BTF_ID_LIST(hid_bpf_btf_ids)
BTF_ID(func, hid_bpf_device_event) /* HID_BPF_PROG_TYPE_DEVICE_EVENT */
BTF_ID(func, hid_bpf_rdesc_fixup) /* HID_BPF_PROG_TYPE_RDESC_FIXUP */
static int hid_bpf_max_programs(enum hid_bpf_prog_type type)
{
switch (type) {
case HID_BPF_PROG_TYPE_DEVICE_EVENT:
return HID_BPF_MAX_PROGS_PER_DEV;
case HID_BPF_PROG_TYPE_RDESC_FIXUP:
return 1;
default:
return -EINVAL;
}
}
static int hid_bpf_program_count(struct hid_device *hdev,
struct bpf_prog *prog,
enum hid_bpf_prog_type type)
{
int i, n = 0;
if (type >= HID_BPF_PROG_TYPE_MAX)
return -EINVAL;
if (type == HID_BPF_PROG_TYPE_RDESC_FIXUP && hdev->bpf.rdesc_ops)
n += 1;
FOR_ENTRIES(i, jmp_table.tail, jmp_table.head) {
struct hid_bpf_prog_entry *entry = &jmp_table.entries[i];
if (type != HID_BPF_PROG_TYPE_UNDEF && entry->type != type)
continue;
if (hdev && entry->hdev != hdev)
continue;
if (prog && entry->prog != prog)
continue;
n++;
}
return n;
}
__weak noinline int __hid_bpf_tail_call(struct hid_bpf_ctx *ctx)
{
return 0;
}
int hid_bpf_prog_run(struct hid_device *hdev, enum hid_bpf_prog_type type,
struct hid_bpf_ctx_kern *ctx_kern)
{
struct hid_bpf_prog_list *prog_list;
int i, idx, err = 0;
rcu_read_lock();
prog_list = rcu_dereference(hdev->bpf.progs[type]);
if (!prog_list)
goto out_unlock;
for (i = 0; i < prog_list->prog_cnt; i++) {
idx = prog_list->prog_idx[i];
if (!test_bit(idx, jmp_table.enabled))
continue;
ctx_kern->ctx.index = idx;
err = __hid_bpf_tail_call(&ctx_kern->ctx);
if (err < 0)
break;
if (err)
ctx_kern->ctx.retval = err;
}
out_unlock:
rcu_read_unlock();
return err;
}
/*
* assign the list of programs attached to a given hid device.
*/
static void __hid_bpf_set_hdev_progs(struct hid_device *hdev, struct hid_bpf_prog_list *new_list,
enum hid_bpf_prog_type type)
{
struct hid_bpf_prog_list *old_list;
spin_lock(&hdev->bpf.progs_lock);
old_list = rcu_dereference_protected(hdev->bpf.progs[type],
lockdep_is_held(&hdev->bpf.progs_lock));
rcu_assign_pointer(hdev->bpf.progs[type], new_list);
spin_unlock(&hdev->bpf.progs_lock);
synchronize_rcu();
kfree(old_list);
}
/*
* allocate and populate the list of programs attached to a given hid device.
*
* Must be called under lock.
*/
static int hid_bpf_populate_hdev(struct hid_device *hdev, enum hid_bpf_prog_type type)
{
struct hid_bpf_prog_list *new_list;
int i;
if (type >= HID_BPF_PROG_TYPE_MAX || !hdev)
return -EINVAL;
if (hdev->bpf.destroyed)
return 0;
new_list = kzalloc(sizeof(*new_list), GFP_KERNEL);
if (!new_list)
return -ENOMEM;
FOR_ENTRIES(i, jmp_table.tail, jmp_table.head) {
struct hid_bpf_prog_entry *entry = &jmp_table.entries[i];
if (entry->type == type && entry->hdev == hdev &&
test_bit(entry->idx, jmp_table.enabled))
new_list->prog_idx[new_list->prog_cnt++] = entry->idx;
}
__hid_bpf_set_hdev_progs(hdev, new_list, type);
return 0;
}
static void __hid_bpf_do_release_prog(int map_fd, unsigned int idx)
{
skel_map_delete_elem(map_fd, &idx);
jmp_table.progs[idx] = NULL;
}
static void hid_bpf_release_progs(struct work_struct *work)
{
int i, j, n, map_fd = -1;
bool hdev_destroyed;
if (!jmp_table.map)
return;
/* retrieve a fd of our prog_array map in BPF */
map_fd = skel_map_get_fd_by_id(jmp_table.map->id);
if (map_fd < 0)
return;
mutex_lock(&hid_bpf_attach_lock); /* protects against attaching new programs */
/* detach unused progs from HID devices */
FOR_ENTRIES(i, jmp_table.tail, jmp_table.head) {
struct hid_bpf_prog_entry *entry = &jmp_table.entries[i];
enum hid_bpf_prog_type type;
struct hid_device *hdev;
if (test_bit(entry->idx, jmp_table.enabled))
continue;
/* we have an attached prog */
if (entry->hdev) {
hdev = entry->hdev;
type = entry->type;
/*
* hdev is still valid, even if we are called after hid_destroy_device():
* when hid_bpf_attach() gets called, it takes a ref on the dev through
* bus_find_device()
*/
hdev_destroyed = hdev->bpf.destroyed;
hid_bpf_populate_hdev(hdev, type);
/* mark all other disabled progs from hdev of the given type as detached */
FOR_ENTRIES(j, i, jmp_table.head) {
struct hid_bpf_prog_entry *next;
next = &jmp_table.entries[j];
if (test_bit(next->idx, jmp_table.enabled))
continue;
if (next->hdev == hdev && next->type == type) {
/*
* clear the hdev reference and decrement the device ref
* that was taken during bus_find_device() while calling
* hid_bpf_attach()
*/
next->hdev = NULL;
put_device(&hdev->dev);
}
}
/* if type was rdesc fixup and the device is not gone, reconnect device */
if (type == HID_BPF_PROG_TYPE_RDESC_FIXUP && !hdev_destroyed)
hid_bpf_reconnect(hdev);
}
}
/* remove all unused progs from the jump table */
FOR_ENTRIES(i, jmp_table.tail, jmp_table.head) {
struct hid_bpf_prog_entry *entry = &jmp_table.entries[i];
if (test_bit(entry->idx, jmp_table.enabled))
continue;
if (entry->prog)
__hid_bpf_do_release_prog(map_fd, entry->idx);
}
/* compact the entry list */
n = jmp_table.tail;
FOR_ENTRIES(i, jmp_table.tail, jmp_table.head) {
struct hid_bpf_prog_entry *entry = &jmp_table.entries[i];
if (!test_bit(entry->idx, jmp_table.enabled))
continue;
jmp_table.entries[n] = jmp_table.entries[i];
n = NEXT(n);
}
jmp_table.head = n;
mutex_unlock(&hid_bpf_attach_lock);
if (map_fd >= 0)
close_fd(map_fd);
}
static void hid_bpf_release_prog_at(int idx)
{
int map_fd = -1;
/* retrieve a fd of our prog_array map in BPF */
map_fd = skel_map_get_fd_by_id(jmp_table.map->id);
if (map_fd < 0)
return;
__hid_bpf_do_release_prog(map_fd, idx);
close(map_fd);
}
/*
* Insert the given BPF program represented by its fd in the jmp table.
* Returns the index in the jump table or a negative error.
*/
static int hid_bpf_insert_prog(int prog_fd, struct bpf_prog *prog)
{
int i, index = -1, map_fd = -1, err = -EINVAL;
/* retrieve a fd of our prog_array map in BPF */
map_fd = skel_map_get_fd_by_id(jmp_table.map->id);
if (map_fd < 0) {
err = -EINVAL;
goto out;
}
/* find the first available index in the jmp_table */
for (i = 0; i < HID_BPF_MAX_PROGS; i++) {
if (!jmp_table.progs[i] && index < 0) {
/* mark the index as used */
jmp_table.progs[i] = prog;
index = i;
__set_bit(i, jmp_table.enabled);
}
}
if (index < 0) {
err = -ENOMEM;
goto out;
}
/* insert the program in the jump table */
err = skel_map_update_elem(map_fd, &index, &prog_fd, 0);
if (err)
goto out;
/* return the index */
err = index;
out:
if (err < 0)
__hid_bpf_do_release_prog(map_fd, index);
if (map_fd >= 0)
close_fd(map_fd);
return err;
}
int hid_bpf_get_prog_attach_type(struct bpf_prog *prog)
{
int prog_type = HID_BPF_PROG_TYPE_UNDEF;
int i;
for (i = 0; i < HID_BPF_PROG_TYPE_MAX; i++) {
if (hid_bpf_btf_ids[i] == prog->aux->attach_btf_id) {
prog_type = i;
break;
}
}
return prog_type;
}
static void hid_bpf_link_release(struct bpf_link *link)
{
struct hid_bpf_link *hid_link =
container_of(link, struct hid_bpf_link, link);
__clear_bit(hid_link->hid_table_index, jmp_table.enabled);
schedule_work(&release_work);
}
static void hid_bpf_link_dealloc(struct bpf_link *link)
{
struct hid_bpf_link *hid_link =
container_of(link, struct hid_bpf_link, link);
kfree(hid_link);
}
static void hid_bpf_link_show_fdinfo(const struct bpf_link *link,
struct seq_file *seq)
{
seq_printf(seq,
"attach_type:\tHID-BPF\n");
}
static const struct bpf_link_ops hid_bpf_link_lops = {
.release = hid_bpf_link_release,
.dealloc = hid_bpf_link_dealloc,
.show_fdinfo = hid_bpf_link_show_fdinfo,
};
/* called from syscall */
noinline int
__hid_bpf_attach_prog(struct hid_device *hdev, enum hid_bpf_prog_type prog_type,
int prog_fd, struct bpf_prog *prog, __u32 flags)
{
struct bpf_link_primer link_primer;
struct hid_bpf_link *link;
struct hid_bpf_prog_entry *prog_entry;
int cnt, err = -EINVAL, prog_table_idx = -1;
mutex_lock(&hid_bpf_attach_lock);
link = kzalloc(sizeof(*link), GFP_USER);
if (!link) {
err = -ENOMEM;
goto err_unlock;
}
bpf_link_init(&link->link, BPF_LINK_TYPE_UNSPEC,
&hid_bpf_link_lops, prog);
/* do not attach too many programs to a given HID device */
cnt = hid_bpf_program_count(hdev, NULL, prog_type);
if (cnt < 0) {
err = cnt;
goto err_unlock;
}
if (cnt >= hid_bpf_max_programs(prog_type)) {
err = -E2BIG;
goto err_unlock;
}
prog_table_idx = hid_bpf_insert_prog(prog_fd, prog);
/* if the jmp table is full, abort */
if (prog_table_idx < 0) {
err = prog_table_idx;
goto err_unlock;
}
if (flags & HID_BPF_FLAG_INSERT_HEAD) {
/* take the previous prog_entry slot */
jmp_table.tail = PREV(jmp_table.tail);
prog_entry = &jmp_table.entries[jmp_table.tail];
} else {
/* take the next prog_entry slot */
prog_entry = &jmp_table.entries[jmp_table.head];
jmp_table.head = NEXT(jmp_table.head);
}
/* we steal the ref here */
prog_entry->prog = prog;
prog_entry->idx = prog_table_idx;
prog_entry->hdev = hdev;
prog_entry->type = prog_type;
/* finally store the index in the device list */
err = hid_bpf_populate_hdev(hdev, prog_type);
if (err) {
hid_bpf_release_prog_at(prog_table_idx);
goto err_unlock;
}
link->hid_table_index = prog_table_idx;
err = bpf_link_prime(&link->link, &link_primer);
if (err)
goto err_unlock;
mutex_unlock(&hid_bpf_attach_lock);
return bpf_link_settle(&link_primer);
err_unlock:
mutex_unlock(&hid_bpf_attach_lock);
kfree(link);
return err;
}
void __hid_bpf_destroy_device(struct hid_device *hdev)
{
int type, i;
struct hid_bpf_prog_list *prog_list;
rcu_read_lock();
for (type = 0; type < HID_BPF_PROG_TYPE_MAX; type++) {
prog_list = rcu_dereference(hdev->bpf.progs[type]);
if (!prog_list)
continue;
for (i = 0; i < prog_list->prog_cnt; i++)
__clear_bit(prog_list->prog_idx[i], jmp_table.enabled);
}
rcu_read_unlock();
for (type = 0; type < HID_BPF_PROG_TYPE_MAX; type++)
__hid_bpf_set_hdev_progs(hdev, NULL, type);
/* schedule release of all detached progs */
schedule_work(&release_work);
}
#define HID_BPF_PROGS_COUNT 1
static struct bpf_link *links[HID_BPF_PROGS_COUNT];
static struct entrypoints_bpf *skel;
void hid_bpf_free_links_and_skel(void)
{
int i;
/* the following is enough to release all programs attached to hid */
if (jmp_table.map)
bpf_map_put_with_uref(jmp_table.map);
for (i = 0; i < ARRAY_SIZE(links); i++) {
if (!IS_ERR_OR_NULL(links[i]))
bpf_link_put(links[i]);
}
entrypoints_bpf__destroy(skel);
}
#define ATTACH_AND_STORE_LINK(__name) do { \
err = entrypoints_bpf__##__name##__attach(skel); \
if (err) \
goto out; \
\
links[idx] = bpf_link_get_from_fd(skel->links.__name##_fd); \
if (IS_ERR(links[idx])) { \
err = PTR_ERR(links[idx]); \
goto out; \
} \
\
/* Avoid taking over stdin/stdout/stderr of init process. Zeroing out \
* makes skel_closenz() a no-op later in iterators_bpf__destroy(). \
*/ \
close_fd(skel->links.__name##_fd); \
skel->links.__name##_fd = 0; \
idx++; \
} while (0)
int hid_bpf_preload_skel(void)
{
int err, idx = 0;
skel = entrypoints_bpf__open();
if (!skel)
return -ENOMEM;
err = entrypoints_bpf__load(skel);
if (err)
goto out;
jmp_table.map = bpf_map_get_with_uref(skel->maps.hid_jmp_table.map_fd);
if (IS_ERR(jmp_table.map)) {
err = PTR_ERR(jmp_table.map);
goto out;
}
ATTACH_AND_STORE_LINK(hid_tail_call);
return 0;
out:
hid_bpf_free_links_and_skel();
return err;
}
include/linux/hid_bpf.h
View file @ 4a86220e
......@@ -4,7 +4,7 @@
#define __HID_BPF_H
#include <linux/bpf.h>
#include <linux/spinlock.h>
#include <linux/mutex.h>
#include <uapi/linux/hid.h>
struct hid_device;
......@@ -24,11 +24,7 @@ struct hid_device;
*
* All of these fields are currently read-only.
*
* @index: program index in the jump table. No special meaning (a smaller index
* doesn't mean the program will be executed before another program with
* a bigger index).
* @hid: the ``struct hid_device`` representing the device itself
* @report_type: used for ``hid_bpf_device_event()``
* @allocated_size: Allocated size of data.
*
* This is how much memory is available and can be requested
......@@ -47,54 +43,21 @@ struct hid_device;
* @retval: Return value of the previous program.
*/
struct hid_bpf_ctx {
__u32 index;
const struct hid_device *hid;
__u32 allocated_size;
enum hid_report_type report_type;
union {
__s32 retval;
__s32 size;
};
};
/**
* enum hid_bpf_attach_flags - flags used when attaching a HIF-BPF program
*
* @HID_BPF_FLAG_NONE: no specific flag is used, the kernel choses where to
* insert the program
* @HID_BPF_FLAG_INSERT_HEAD: insert the given program before any other program
* currently attached to the device. This doesn't
* guarantee that this program will always be first
*/
enum hid_bpf_attach_flags {
HID_BPF_FLAG_NONE = 0,
HID_BPF_FLAG_INSERT_HEAD = _BITUL(0),
/* private: internal use only */
HID_BPF_FLAG_MAX,
};
/* Following functions are tracepoints that BPF programs can attach to */
int hid_bpf_device_event(struct hid_bpf_ctx *ctx);
int hid_bpf_rdesc_fixup(struct hid_bpf_ctx *ctx);
/*
* Below is HID internal
*/
/* internal function to call eBPF programs, not to be used by anybody */
int __hid_bpf_tail_call(struct hid_bpf_ctx *ctx);
#define HID_BPF_MAX_PROGS_PER_DEV 64
#define HID_BPF_FLAG_MASK (((HID_BPF_FLAG_MAX - 1) << 1) - 1)
/* types of HID programs to attach to */
enum hid_bpf_prog_type {
HID_BPF_PROG_TYPE_UNDEF = -1,
HID_BPF_PROG_TYPE_DEVICE_EVENT, /* an event is emitted from the device */
HID_BPF_PROG_TYPE_RDESC_FIXUP,
HID_BPF_PROG_TYPE_MAX,
};
struct hid_report_enum;
......@@ -167,11 +130,6 @@ struct hid_bpf_ops {
struct hid_device *hdev;
};
struct hid_bpf_prog_list {
u16 prog_idx[HID_BPF_MAX_PROGS_PER_DEV];
u8 prog_cnt;
};
/* stored in each device */
struct hid_bpf {
u8 *device_data; /* allocated when a bpf program of type
......@@ -179,23 +137,13 @@ struct hid_bpf {
* to this HID device
*/
u32 allocated_data;
struct hid_bpf_prog_list __rcu *progs[HID_BPF_PROG_TYPE_MAX]; /* attached BPF progs */
bool destroyed; /* prevents the assignment of any progs */
spinlock_t progs_lock; /* protects RCU update of progs */
struct hid_bpf_ops *rdesc_ops;
struct list_head prog_list;
struct mutex prog_list_lock; /* protects prog_list update */
};
/* specific HID-BPF link when a program is attached to a device */
struct hid_bpf_link {
struct bpf_link link;
int hid_table_index;
};
#ifdef CONFIG_HID_BPF
u8 *dispatch_hid_bpf_device_event(struct hid_device *hid, enum hid_report_type type, u8 *data,
u32 *size, int interrupt);
......
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