The purpose of this series is to rethink how HID-BPF is invoked.
Currently it implies a jmp table, a prog fd bpf_map, a preloaded tracing
bpf program and a lot of manual work for handling the bpf program
lifetime and addition/removal.
OTOH, bpf_struct_ops take care of most of the bpf handling leaving us
with a simple list of ops pointers, and we can directly call the
struct_ops program from the kernel as a regular function.
The net gain right now is in term of code simplicity and lines of code
removal (though is an API breakage), but udev-hid-bpf is able to handle
such breakages.
In the near future, we will be able to extend the HID-BPF struct_ops
with entrypoints for hid_hw_raw_request() and hid_hw_output_report(),
allowing for covering all of the initial use cases:
- firewalling a HID device
- fixing all of the HID device interactions (not just device events as
it is right now).
The matching user-space loader (udev-hid-bpf) MR is at
https://gitlab.freedesktop.org/libevdev/udev-hid-bpf/-/merge_requests/86
I'll put it out of draft once this is merged.
Cheers,
Benjamin
Signed-off-by: Benjamin Tissoires <[email protected]>
---
Changes in v3:
- took Alexei's review into account
- Link to v2: https://lore.kernel.org/r/[email protected]
Changes in v2:
- drop HID_BPF_FLAGS enum and use BPF_F_BEFORE instead
- fix .init_members to not open code member->offset
- allow struct hid_device to be writeable from HID-BPF for its name,
uniq and phys
- Link to v1: https://lore.kernel.org/r/[email protected]
---
Benjamin Tissoires (16):
HID: rename struct hid_bpf_ops into hid_ops
HID: bpf: add hid_get/put_device() helpers
HID: bpf: implement HID-BPF through bpf_struct_ops
selftests/hid: convert the hid_bpf selftests with struct_ops
HID: samples: convert the 2 HID-BPF samples into struct_ops
HID: bpf: add defines for HID-BPF SEC in in-tree bpf fixes
HID: bpf: convert in-tree fixes into struct_ops
HID: bpf: remove tracing HID-BPF capability
selftests/hid: add subprog call test
Documentation: HID: amend HID-BPF for struct_ops
Documentation: HID: add a small blurb on udev-hid-bpf
HID: bpf: Artist24: remove unused variable
HID: bpf: error on warnings when compiling bpf objects
bpf: allow bpf helpers to be used into HID-BPF struct_ops
HID: bpf: rework hid_bpf_ops_btf_struct_access
HID: bpf: make part of struct hid_device writable
Documentation/hid/hid-bpf.rst | 173 ++++---
drivers/hid/bpf/Makefile | 2 +-
drivers/hid/bpf/entrypoints/Makefile | 93 ----
drivers/hid/bpf/entrypoints/README | 4 -
drivers/hid/bpf/entrypoints/entrypoints.bpf.c | 25 -
drivers/hid/bpf/entrypoints/entrypoints.lskel.h | 248 ---------
drivers/hid/bpf/hid_bpf_dispatch.c | 266 +++-------
drivers/hid/bpf/hid_bpf_dispatch.h | 12 +-
drivers/hid/bpf/hid_bpf_jmp_table.c | 565 ---------------------
drivers/hid/bpf/hid_bpf_struct_ops.c | 298 +++++++++++
drivers/hid/bpf/progs/FR-TEC__Raptor-Mach-2.bpf.c | 9 +-
drivers/hid/bpf/progs/HP__Elite-Presenter.bpf.c | 6 +-
drivers/hid/bpf/progs/Huion__Kamvas-Pro-19.bpf.c | 9 +-
.../hid/bpf/progs/IOGEAR__Kaliber-MMOmentum.bpf.c | 6 +-
drivers/hid/bpf/progs/Makefile | 2 +-
.../hid/bpf/progs/Microsoft__XBox-Elite-2.bpf.c | 6 +-
drivers/hid/bpf/progs/Wacom__ArtPen.bpf.c | 6 +-
drivers/hid/bpf/progs/XPPen__Artist24.bpf.c | 10 +-
drivers/hid/bpf/progs/XPPen__ArtistPro16Gen2.bpf.c | 24 +-
drivers/hid/bpf/progs/hid_bpf.h | 5 +
drivers/hid/hid-core.c | 6 +-
include/linux/hid_bpf.h | 119 +++--
samples/hid/Makefile | 5 +-
samples/hid/hid_bpf_attach.bpf.c | 18 -
samples/hid/hid_bpf_attach.h | 14 -
samples/hid/hid_mouse.bpf.c | 26 +-
samples/hid/hid_mouse.c | 39 +-
samples/hid/hid_surface_dial.bpf.c | 10 +-
samples/hid/hid_surface_dial.c | 53 +-
tools/testing/selftests/hid/hid_bpf.c | 100 +++-
tools/testing/selftests/hid/progs/hid.c | 100 +++-
.../testing/selftests/hid/progs/hid_bpf_helpers.h | 19 +-
32 files changed, 800 insertions(+), 1478 deletions(-)
---
base-commit: 70ec81c2e2b4005465ad0d042e90b36087c36104
change-id: 20240513-hid_bpf_struct_ops-e3212a224555
Best regards,
--
Benjamin Tissoires <[email protected]>
I got a weird verifier error with a subprog once, so let's have a test
for it.
Signed-off-by: Benjamin Tissoires <[email protected]>
---
no changes in v3
no changes in v2
---
tools/testing/selftests/hid/hid_bpf.c | 41 +++++++++++++++++++++++++++++++++
tools/testing/selftests/hid/progs/hid.c | 24 +++++++++++++++++++
2 files changed, 65 insertions(+)
diff --git a/tools/testing/selftests/hid/hid_bpf.c b/tools/testing/selftests/hid/hid_bpf.c
index 967dfe6b58cb..45e173db35bd 100644
--- a/tools/testing/selftests/hid/hid_bpf.c
+++ b/tools/testing/selftests/hid/hid_bpf.c
@@ -638,6 +638,47 @@ TEST_F(hid_bpf, raw_event)
ASSERT_EQ(buf[2], 52);
}
+/*
+ * Attach hid_first_event to the given uhid device,
+ * retrieve and open the matching hidraw node,
+ * inject one event in the uhid device,
+ * check that the program sees it and can change the data
+ */
+TEST_F(hid_bpf, subprog_raw_event)
+{
+ const struct test_program progs[] = {
+ { .name = "hid_subprog_first_event" },
+ };
+ __u8 buf[10] = {0};
+ int err;
+
+ LOAD_PROGRAMS(progs);
+
+ /* inject one event */
+ buf[0] = 1;
+ buf[1] = 42;
+ uhid_send_event(_metadata, self->uhid_fd, buf, 6);
+
+ /* read the data from hidraw */
+ memset(buf, 0, sizeof(buf));
+ err = read(self->hidraw_fd, buf, sizeof(buf));
+ ASSERT_EQ(err, 6) TH_LOG("read_hidraw");
+ ASSERT_EQ(buf[0], 1);
+ ASSERT_EQ(buf[2], 47);
+
+ /* inject another event */
+ memset(buf, 0, sizeof(buf));
+ buf[0] = 1;
+ buf[1] = 47;
+ uhid_send_event(_metadata, self->uhid_fd, buf, 6);
+
+ /* read the data from hidraw */
+ memset(buf, 0, sizeof(buf));
+ err = read(self->hidraw_fd, buf, sizeof(buf));
+ ASSERT_EQ(err, 6) TH_LOG("read_hidraw");
+ ASSERT_EQ(buf[2], 52);
+}
+
/*
* Ensures that we can attach/detach programs
*/
diff --git a/tools/testing/selftests/hid/progs/hid.c b/tools/testing/selftests/hid/progs/hid.c
index 614f1aa32649..2e7e5a736dc6 100644
--- a/tools/testing/selftests/hid/progs/hid.c
+++ b/tools/testing/selftests/hid/progs/hid.c
@@ -35,6 +35,30 @@ struct hid_bpf_ops first_event = {
.hid_id = 2,
};
+int __hid_subprog_first_event(struct hid_bpf_ctx *hid_ctx, enum hid_report_type type)
+{
+ __u8 *rw_data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 3 /* size */);
+
+ if (!rw_data)
+ return 0; /* EPERM check */
+
+ rw_data[2] = rw_data[1] + 5;
+
+ return hid_ctx->size;
+}
+
+SEC("?struct_ops/hid_device_event")
+int BPF_PROG(hid_subprog_first_event, struct hid_bpf_ctx *hid_ctx, enum hid_report_type type)
+{
+ return __hid_subprog_first_event(hid_ctx, type);
+}
+
+SEC(".struct_ops.link")
+struct hid_bpf_ops subprog_first_event = {
+ .hid_device_event = (void *)hid_subprog_first_event,
+ .hid_id = 2,
+};
+
SEC("?struct_ops/hid_device_event")
int BPF_PROG(hid_second_event, struct hid_bpf_ctx *hid_ctx, enum hid_report_type type)
{
--
2.44.0
We can now rely on struct_ops as we cleared the users in-tree.
Signed-off-by: Benjamin Tissoires <[email protected]>
---
no changes in v3
changes in v2:
- remove now unused enum hid_bpf_attach_flags
---
drivers/hid/bpf/Makefile | 2 +-
drivers/hid/bpf/entrypoints/Makefile | 93 ----
drivers/hid/bpf/entrypoints/README | 4 -
drivers/hid/bpf/entrypoints/entrypoints.bpf.c | 25 --
drivers/hid/bpf/entrypoints/entrypoints.lskel.h | 248 -----------
drivers/hid/bpf/hid_bpf_dispatch.c | 193 +-------
drivers/hid/bpf/hid_bpf_dispatch.h | 8 -
drivers/hid/bpf/hid_bpf_jmp_table.c | 568 ------------------------
include/linux/hid_bpf.h | 54 +--
9 files changed, 8 insertions(+), 1187 deletions(-)
diff --git a/drivers/hid/bpf/Makefile b/drivers/hid/bpf/Makefile
index 1cb3f31e9335..d1f2b81788ca 100644
--- a/drivers/hid/bpf/Makefile
+++ b/drivers/hid/bpf/Makefile
@@ -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
diff --git a/drivers/hid/bpf/entrypoints/Makefile b/drivers/hid/bpf/entrypoints/Makefile
deleted file mode 100644
index 43b99b5575cf..000000000000
--- a/drivers/hid/bpf/entrypoints/Makefile
+++ /dev/null
@@ -1,93 +0,0 @@
-# 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
diff --git a/drivers/hid/bpf/entrypoints/README b/drivers/hid/bpf/entrypoints/README
deleted file mode 100644
index 147e0d41509f..000000000000
--- a/drivers/hid/bpf/entrypoints/README
+++ /dev/null
@@ -1,4 +0,0 @@
-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
diff --git a/drivers/hid/bpf/entrypoints/entrypoints.bpf.c b/drivers/hid/bpf/entrypoints/entrypoints.bpf.c
deleted file mode 100644
index c22921125a1a..000000000000
--- a/drivers/hid/bpf/entrypoints/entrypoints.bpf.c
+++ /dev/null
@@ -1,25 +0,0 @@
-// 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";
diff --git a/drivers/hid/bpf/entrypoints/entrypoints.lskel.h b/drivers/hid/bpf/entrypoints/entrypoints.lskel.h
deleted file mode 100644
index 35618051598c..000000000000
--- a/drivers/hid/bpf/entrypoints/entrypoints.lskel.h
+++ /dev/null
@@ -1,248 +0,0 @@
-/* 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 *)"\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
-\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\
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-\0\0";
- opts.insns_sz = 1192;
- opts.insns = (void *)"\
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-\0\0\x63\x7a\x80\xff\0\0\0\0\x61\xa1\x78\xff\0\0\0\0\xd5\x01\x02\0\0\0\0\0\xbf\
-\x19\0\0\0\0\0\0\x85\0\0\0\xa8\0\0\0\x61\xa0\x80\xff\0\0\0\0\x63\x06\x28\0\0\0\
-\0\0\x18\x61\0\0\0\0\0\0\0\0\0\0\0\0\0\0\x61\x10\0\0\0\0\0\0\x63\x06\x18\0\0\0\
-\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__ */
diff --git a/drivers/hid/bpf/hid_bpf_dispatch.c b/drivers/hid/bpf/hid_bpf_dispatch.c
index 7216c3c7713d..06cc628e7bb4 100644
--- a/drivers/hid/bpf/hid_bpf_dispatch.c
+++ b/drivers/hid/bpf/hid_bpf_dispatch.c
@@ -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);
+ ret = hdev->bpf.rdesc_ops->hid_rdesc_fixup(&ctx_kern.ctx);
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");
diff --git a/drivers/hid/bpf/hid_bpf_dispatch.h b/drivers/hid/bpf/hid_bpf_dispatch.h
index e52c43d81650..835e6f69f479 100644
--- a/drivers/hid/bpf/hid_bpf_dispatch.h
+++ b/drivers/hid/bpf/hid_bpf_dispatch.h
@@ -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;
diff --git a/drivers/hid/bpf/hid_bpf_jmp_table.c b/drivers/hid/bpf/hid_bpf_jmp_table.c
deleted file mode 100644
index 8a54ba447718..000000000000
--- a/drivers/hid/bpf/hid_bpf_jmp_table.c
+++ /dev/null
@@ -1,568 +0,0 @@
-// 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;
-}
diff --git a/include/linux/hid_bpf.h b/include/linux/hid_bpf.h
index c4f4ce10b7dd..447b94aa99ab 100644
--- a/include/linux/hid_bpf.h
+++ b/include/linux/hid_bpf.h
@@ -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);
--
2.44.0
This is the current decision we took: we don't provide automatic loading
of HID-BPF by the kernel directly, but rely on an external tool for it.
This tool is currently udev-hid-bpf, so let's make people aware of it.
Signed-off-by: Benjamin Tissoires <[email protected]>
---
no changes in v3
no changes in v2
---
Documentation/hid/hid-bpf.rst | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/Documentation/hid/hid-bpf.rst b/Documentation/hid/hid-bpf.rst
index 456e15097d87..8ae8f49801cb 100644
--- a/Documentation/hid/hid-bpf.rst
+++ b/Documentation/hid/hid-bpf.rst
@@ -129,6 +129,23 @@ When a BPF program needs to emit input events, it needs to talk with the HID
protocol, and rely on the HID kernel processing to translate the HID data into
input events.
+In-tree HID-BPF programs and ``udev-hid-bpf``
+=============================================
+
+Official device fixes are shipped in the kernel tree as source in the
+``drivers/hid/bpf/progs`` directory. This allows to add selftests to them in
+``tools/testing/selftests/hid``.
+
+However, the compilation of these objects is not part of a regular kernel compilation
+given that they need an external tool to be loaded. This tool is currently
+`udev-hid-bpf <https://libevdev.pages.freedesktop.org/udev-hid-bpf/index.html>`_.
+
+For convenience, that external repository duplicates the files from here in
+``drivers/hid/bpf/progs`` into its own ``src/bpf/stable`` directory. This allows
+distributions to not have to pull the entire kernel source tree to ship and package
+those HID-BPF fixes. ``udev-hid-bpf`` also has capabilities of handling multiple
+objects files depending on the kernel the user is running.
+
Available types of programs
===========================
--
2.44.0
There is no real reasons to paper over warnings for such small programs.
Signed-off-by: Benjamin Tissoires <[email protected]>
---
no changes in v3
no changes in v2
---
drivers/hid/bpf/progs/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/hid/bpf/progs/Makefile b/drivers/hid/bpf/progs/Makefile
index 63ed7e02adf1..ec1fc642fd63 100644
--- a/drivers/hid/bpf/progs/Makefile
+++ b/drivers/hid/bpf/progs/Makefile
@@ -56,7 +56,7 @@ clean:
%.bpf.o: %.bpf.c vmlinux.h $(BPFOBJ) | $(OUTPUT)
$(call msg,BPF,$@)
- $(Q)$(CLANG) -g -O2 --target=bpf $(INCLUDES) \
+ $(Q)$(CLANG) -g -O2 --target=bpf -Wall -Werror $(INCLUDES) \
-c $(filter %.c,$^) -o $@ && \
$(LLVM_STRIP) -g $@
--
2.44.0
This is mostly mechanical: attach_prog is dropped, and
the SEC are converted into struct_ops.
Signed-off-by: Benjamin Tissoires <[email protected]>
---
no changes in v3
no changes in v2 but the commit message.
---
samples/hid/Makefile | 5 ++--
samples/hid/hid_bpf_attach.bpf.c | 18 -------------
samples/hid/hid_bpf_attach.h | 14 ----------
samples/hid/hid_mouse.bpf.c | 26 +++++++++++++++----
samples/hid/hid_mouse.c | 39 ++++++++--------------------
samples/hid/hid_surface_dial.bpf.c | 10 +++++--
samples/hid/hid_surface_dial.c | 53 +++++++++++---------------------------
7 files changed, 57 insertions(+), 108 deletions(-)
diff --git a/samples/hid/Makefile b/samples/hid/Makefile
index c128ccd49974..8ea59e9631a3 100644
--- a/samples/hid/Makefile
+++ b/samples/hid/Makefile
@@ -16,7 +16,6 @@ LIBBPF_DESTDIR = $(LIBBPF_OUTPUT)
LIBBPF_INCLUDE = $(LIBBPF_DESTDIR)/include
LIBBPF = $(LIBBPF_OUTPUT)/libbpf.a
-EXTRA_HEADERS := hid_bpf_attach.h
EXTRA_BPF_HEADERS := hid_bpf_helpers.h
hid_mouse-objs := hid_mouse.o
@@ -207,8 +206,8 @@ $(obj)/%.bpf.o: $(src)/%.bpf.c $(EXTRA_BPF_HEADERS_SRC) $(obj)/vmlinux.h
LINKED_SKELS := hid_mouse.skel.h hid_surface_dial.skel.h
clean-files += $(LINKED_SKELS)
-hid_mouse.skel.h-deps := hid_mouse.bpf.o hid_bpf_attach.bpf.o
-hid_surface_dial.skel.h-deps := hid_surface_dial.bpf.o hid_bpf_attach.bpf.o
+hid_mouse.skel.h-deps := hid_mouse.bpf.o
+hid_surface_dial.skel.h-deps := hid_surface_dial.bpf.o
LINKED_BPF_SRCS := $(patsubst %.bpf.o,%.bpf.c,$(foreach skel,$(LINKED_SKELS),$($(skel)-deps)))
diff --git a/samples/hid/hid_bpf_attach.bpf.c b/samples/hid/hid_bpf_attach.bpf.c
deleted file mode 100644
index d4dce4ea7c6e..000000000000
--- a/samples/hid/hid_bpf_attach.bpf.c
+++ /dev/null
@@ -1,18 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/* Copyright (c) 2022 Benjamin Tissoires
- */
-
-#include "vmlinux.h"
-#include <bpf/bpf_helpers.h>
-#include <bpf/bpf_tracing.h>
-#include "hid_bpf_attach.h"
-#include "hid_bpf_helpers.h"
-
-SEC("syscall")
-int attach_prog(struct attach_prog_args *ctx)
-{
- ctx->retval = hid_bpf_attach_prog(ctx->hid,
- ctx->prog_fd,
- 0);
- return 0;
-}
diff --git a/samples/hid/hid_bpf_attach.h b/samples/hid/hid_bpf_attach.h
deleted file mode 100644
index 35bb28b49264..000000000000
--- a/samples/hid/hid_bpf_attach.h
+++ /dev/null
@@ -1,14 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/* Copyright (c) 2022 Benjamin Tissoires
- */
-
-#ifndef __HID_BPF_ATTACH_H
-#define __HID_BPF_ATTACH_H
-
-struct attach_prog_args {
- int prog_fd;
- unsigned int hid;
- int retval;
-};
-
-#endif /* __HID_BPF_ATTACH_H */
diff --git a/samples/hid/hid_mouse.bpf.c b/samples/hid/hid_mouse.bpf.c
index 7c8b453ccb16..bd901fa855c9 100644
--- a/samples/hid/hid_mouse.bpf.c
+++ b/samples/hid/hid_mouse.bpf.c
@@ -5,8 +5,7 @@
#include <bpf/bpf_tracing.h>
#include "hid_bpf_helpers.h"
-SEC("fmod_ret/hid_bpf_device_event")
-int BPF_PROG(hid_y_event, struct hid_bpf_ctx *hctx)
+static int hid_y_event(struct hid_bpf_ctx *hctx)
{
s16 y;
__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 9 /* size */);
@@ -51,8 +50,7 @@ int BPF_PROG(hid_y_event, struct hid_bpf_ctx *hctx)
return 0;
}
-SEC("fmod_ret/hid_bpf_device_event")
-int BPF_PROG(hid_x_event, struct hid_bpf_ctx *hctx)
+static int hid_x_event(struct hid_bpf_ctx *hctx)
{
s16 x;
__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 9 /* size */);
@@ -69,7 +67,19 @@ int BPF_PROG(hid_x_event, struct hid_bpf_ctx *hctx)
return 0;
}
-SEC("fmod_ret/hid_bpf_rdesc_fixup")
+SEC("struct_ops/device_event")
+int BPF_PROG(hid_event, struct hid_bpf_ctx *hctx, enum hid_report_type type)
+{
+ int ret = hid_y_event(hctx);
+
+ if (ret)
+ return ret;
+
+ return hid_x_event(hctx);
+}
+
+
+SEC("struct_ops/rdesc_fixup")
int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hctx)
{
__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 4096 /* size */);
@@ -109,4 +119,10 @@ int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hctx)
return 0;
}
+SEC(".struct_ops.link")
+struct hid_bpf_ops mouse_invert = {
+ .rdesc_fixup = (void *)hid_rdesc_fixup,
+ .device_event = (void *)hid_event,
+};
+
char _license[] SEC("license") = "GPL";
diff --git a/samples/hid/hid_mouse.c b/samples/hid/hid_mouse.c
index 018f1185f203..4b80d4e4c154 100644
--- a/samples/hid/hid_mouse.c
+++ b/samples/hid/hid_mouse.c
@@ -29,7 +29,6 @@
#include <bpf/libbpf.h>
#include "hid_mouse.skel.h"
-#include "hid_bpf_attach.h"
static bool running = true;
@@ -76,18 +75,11 @@ static int get_hid_id(const char *path)
int main(int argc, char **argv)
{
struct hid_mouse *skel;
- struct bpf_program *prog;
+ struct bpf_link *link;
int err;
const char *optstr = "";
const char *sysfs_path;
- int opt, hid_id, attach_fd;
- struct attach_prog_args args = {
- .retval = -1,
- };
- DECLARE_LIBBPF_OPTS(bpf_test_run_opts, tattr,
- .ctx_in = &args,
- .ctx_size_in = sizeof(args),
- );
+ int opt, hid_id;
while ((opt = getopt(argc, argv, optstr)) != -1) {
switch (opt) {
@@ -108,7 +100,7 @@ int main(int argc, char **argv)
return 1;
}
- skel = hid_mouse__open_and_load();
+ skel = hid_mouse__open();
if (!skel) {
fprintf(stderr, "%s %s:%d", __func__, __FILE__, __LINE__);
return -1;
@@ -120,27 +112,18 @@ int main(int argc, char **argv)
fprintf(stderr, "can not open HID device: %m\n");
return 1;
}
- args.hid = hid_id;
+ skel->struct_ops.mouse_invert->hid_id = hid_id;
- attach_fd = bpf_program__fd(skel->progs.attach_prog);
- if (attach_fd < 0) {
- fprintf(stderr, "can't locate attach prog: %m\n");
+ err = hid_mouse__load(skel);
+ if (err < 0) {
+ fprintf(stderr, "can not load HID-BPF program: %m\n");
return 1;
}
- bpf_object__for_each_program(prog, *skel->skeleton->obj) {
- /* ignore syscalls */
- if (bpf_program__get_type(prog) != BPF_PROG_TYPE_TRACING)
- continue;
-
- args.retval = -1;
- args.prog_fd = bpf_program__fd(prog);
- err = bpf_prog_test_run_opts(attach_fd, &tattr);
- if (err) {
- fprintf(stderr, "can't attach prog to hid device %d: %m (err: %d)\n",
- hid_id, err);
- return 1;
- }
+ link = bpf_map__attach_struct_ops(skel->maps.mouse_invert);
+ if (!link) {
+ fprintf(stderr, "can not attach HID-BPF program: %m\n");
+ return 1;
}
signal(SIGINT, int_exit);
diff --git a/samples/hid/hid_surface_dial.bpf.c b/samples/hid/hid_surface_dial.bpf.c
index 1f80478c0918..d8d0fb07391f 100644
--- a/samples/hid/hid_surface_dial.bpf.c
+++ b/samples/hid/hid_surface_dial.bpf.c
@@ -10,7 +10,7 @@
#define HID_UP_BUTTON 0x0009
#define HID_GD_WHEEL 0x0038
-SEC("fmod_ret/hid_bpf_device_event")
+SEC("struct_ops/device_event")
int BPF_PROG(hid_event, struct hid_bpf_ctx *hctx)
{
__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 9 /* size */);
@@ -101,7 +101,7 @@ int set_haptic(struct haptic_syscall_args *args)
}
/* Convert REL_DIAL into REL_WHEEL */
-SEC("fmod_ret/hid_bpf_rdesc_fixup")
+SEC("struct_ops/rdesc_fixup")
int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hctx)
{
__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 4096 /* size */);
@@ -130,5 +130,11 @@ int BPF_PROG(hid_rdesc_fixup, struct hid_bpf_ctx *hctx)
return 0;
}
+SEC(".struct_ops.link")
+struct hid_bpf_ops surface_dial = {
+ .rdesc_fixup = (void *)hid_rdesc_fixup,
+ .device_event = (void *)hid_event,
+};
+
char _license[] SEC("license") = "GPL";
u32 _version SEC("version") = 1;
diff --git a/samples/hid/hid_surface_dial.c b/samples/hid/hid_surface_dial.c
index 4bc97373a708..9dd363845a85 100644
--- a/samples/hid/hid_surface_dial.c
+++ b/samples/hid/hid_surface_dial.c
@@ -31,7 +31,6 @@
#include <bpf/libbpf.h>
#include "hid_surface_dial.skel.h"
-#include "hid_bpf_attach.h"
static bool running = true;
@@ -86,34 +85,6 @@ static int get_hid_id(const char *path)
return (int)strtol(str_id, NULL, 16);
}
-static int attach_prog(struct hid_surface_dial *skel, struct bpf_program *prog, int hid_id)
-{
- struct attach_prog_args args = {
- .hid = hid_id,
- .retval = -1,
- };
- int attach_fd, err;
- DECLARE_LIBBPF_OPTS(bpf_test_run_opts, tattr,
- .ctx_in = &args,
- .ctx_size_in = sizeof(args),
- );
-
- attach_fd = bpf_program__fd(skel->progs.attach_prog);
- if (attach_fd < 0) {
- fprintf(stderr, "can't locate attach prog: %m\n");
- return 1;
- }
-
- args.prog_fd = bpf_program__fd(prog);
- err = bpf_prog_test_run_opts(attach_fd, &tattr);
- if (err) {
- fprintf(stderr, "can't attach prog to hid device %d: %m (err: %d)\n",
- hid_id, err);
- return 1;
- }
- return 0;
-}
-
static int set_haptic(struct hid_surface_dial *skel, int hid_id)
{
struct haptic_syscall_args args = {
@@ -144,10 +115,10 @@ static int set_haptic(struct hid_surface_dial *skel, int hid_id)
int main(int argc, char **argv)
{
struct hid_surface_dial *skel;
- struct bpf_program *prog;
const char *optstr = "r:";
+ struct bpf_link *link;
const char *sysfs_path;
- int opt, hid_id, resolution = 72;
+ int err, opt, hid_id, resolution = 72;
while ((opt = getopt(argc, argv, optstr)) != -1) {
switch (opt) {
@@ -189,7 +160,7 @@ int main(int argc, char **argv)
return 1;
}
- skel = hid_surface_dial__open_and_load();
+ skel = hid_surface_dial__open();
if (!skel) {
fprintf(stderr, "%s %s:%d", __func__, __FILE__, __LINE__);
return -1;
@@ -201,15 +172,21 @@ int main(int argc, char **argv)
return 1;
}
+ skel->struct_ops.surface_dial->hid_id = hid_id;
+
+ err = hid_surface_dial__load(skel);
+ if (err < 0) {
+ fprintf(stderr, "can not load HID-BPF program: %m\n");
+ return 1;
+ }
+
skel->data->resolution = resolution;
skel->data->physical = (int)(resolution / 72);
- bpf_object__for_each_program(prog, *skel->skeleton->obj) {
- /* ignore syscalls */
- if (bpf_program__get_type(prog) != BPF_PROG_TYPE_TRACING)
- continue;
-
- attach_prog(skel, prog, hid_id);
+ link = bpf_map__attach_struct_ops(skel->maps.surface_dial);
+ if (!link) {
+ fprintf(stderr, "can not attach HID-BPF program: %m\n");
+ return 1;
}
signal(SIGINT, int_exit);
--
2.44.0
Without this helpers like bpf_printk() or bpf_map_update() are not
available, making anything but change of bytes impossible to do.
Signed-off-by: Benjamin Tissoires <[email protected]>
---
no changes in v3
new in v2
---
drivers/hid/bpf/hid_bpf_struct_ops.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/hid/bpf/hid_bpf_struct_ops.c b/drivers/hid/bpf/hid_bpf_struct_ops.c
index 9192c66cde20..056d05d96962 100644
--- a/drivers/hid/bpf/hid_bpf_struct_ops.c
+++ b/drivers/hid/bpf/hid_bpf_struct_ops.c
@@ -89,6 +89,7 @@ static int hid_bpf_ops_btf_struct_access(struct bpf_verifier_log *log,
}
static const struct bpf_verifier_ops hid_bpf_verifier_ops = {
+ .get_func_proto = bpf_base_func_proto,
.is_valid_access = hid_bpf_ops_is_valid_access,
.btf_struct_access = hid_bpf_ops_btf_struct_access,
};
--
2.44.0
The idea is to provide a list of stucts and their editable fields.
Currently no functional changes are introduced here, we will add some
more writeable fields in the next patch.
Signed-off-by: Benjamin Tissoires <[email protected]>
---
changes in v3:
- rewrote WRITE_RANGE macro to not deal with offset from the caller side
new in v2
---
drivers/hid/bpf/hid_bpf_struct_ops.c | 91 +++++++++++++++++++++++++++---------
1 file changed, 69 insertions(+), 22 deletions(-)
diff --git a/drivers/hid/bpf/hid_bpf_struct_ops.c b/drivers/hid/bpf/hid_bpf_struct_ops.c
index 056d05d96962..b14eccb121e0 100644
--- a/drivers/hid/bpf/hid_bpf_struct_ops.c
+++ b/drivers/hid/bpf/hid_bpf_struct_ops.c
@@ -16,6 +16,7 @@
#include <linux/hid_bpf.h>
#include <linux/init.h>
#include <linux/module.h>
+#include <linux/stddef.h>
#include <linux/workqueue.h>
#include "hid_bpf_dispatch.h"
@@ -52,40 +53,86 @@ static int hid_bpf_ops_check_member(const struct btf_type *t,
return 0;
}
+struct hid_bpf_offset_write_range {
+ const char *struct_name;
+ u32 struct_length;
+ u32 start;
+ u32 end;
+};
+
static int hid_bpf_ops_btf_struct_access(struct bpf_verifier_log *log,
const struct bpf_reg_state *reg,
int off, int size)
{
- const struct btf_type *state;
- const struct btf_type *t;
- s32 type_id;
+#define WRITE_RANGE(_name, _field, _is_string) \
+ { \
+ .struct_name = #_name, \
+ .struct_length = sizeof(struct _name), \
+ .start = offsetof(struct _name, _field), \
+ .end = offsetofend(struct _name, _field) - !!(_is_string), \
+ }
- type_id = btf_find_by_name_kind(reg->btf, "hid_bpf_ctx",
- BTF_KIND_STRUCT);
- if (type_id < 0)
- return -EINVAL;
+ const struct hid_bpf_offset_write_range write_ranges[] = {
+ WRITE_RANGE(hid_bpf_ctx, retval, false),
+ };
+#undef WRITE_RANGE
+ const struct btf_type *state = NULL;
+ const struct btf_type *t;
+ const char *cur = NULL;
+ int i;
t = btf_type_by_id(reg->btf, reg->btf_id);
- state = btf_type_by_id(reg->btf, type_id);
- if (t != state) {
- bpf_log(log, "only access to hid_bpf_ctx is supported\n");
- return -EACCES;
- }
- /* out-of-bound access in hid_bpf_ctx */
- if (off + size > sizeof(struct hid_bpf_ctx)) {
- bpf_log(log, "write access at off %d with size %d\n", off, size);
- return -EACCES;
+ for (i = 0; i < ARRAY_SIZE(write_ranges); i++) {
+ const struct hid_bpf_offset_write_range *write_range = &write_ranges[i];
+ s32 type_id;
+
+ /* we already found a writeable struct, but there is a
+ * new one, let's break the loop.
+ */
+ if (t == state && write_range->struct_name != cur)
+ break;
+
+ /* new struct to look for */
+ if (write_range->struct_name != cur) {
+ type_id = btf_find_by_name_kind(reg->btf, write_range->struct_name,
+ BTF_KIND_STRUCT);
+ if (type_id < 0)
+ return -EINVAL;
+
+ state = btf_type_by_id(reg->btf, type_id);
+ }
+
+ /* this is not the struct we are looking for */
+ if (t != state) {
+ cur = write_range->struct_name;
+ continue;
+ }
+
+ /* first time we see this struct, check for out of bounds */
+ if (cur != write_range->struct_name &&
+ off + size > write_range->struct_length) {
+ bpf_log(log, "write access for struct %s at off %d with size %d\n",
+ write_range->struct_name, off, size);
+ return -EACCES;
+ }
+
+ /* now check if we are in our boundaries */
+ if (off >= write_range->start && off + size <= write_range->end)
+ return NOT_INIT;
+
+ cur = write_range->struct_name;
}
- if (off < offsetof(struct hid_bpf_ctx, retval)) {
+
+ if (t != state)
+ bpf_log(log, "write access to this struct is not supported\n");
+ else
bpf_log(log,
- "write access at off %d with size %d on read-only part of hid_bpf_ctx\n",
- off, size);
- return -EACCES;
- }
+ "write access at off %d with size %d on read-only part of %s\n",
+ off, size, cur);
- return NOT_INIT;
+ return -EACCES;
}
static const struct bpf_verifier_ops hid_bpf_verifier_ops = {
--
2.44.0
It is useful to change the name, the phys and/or the uniq of a
struct hid_device during .rdesc_fixup().
For example, hid-uclogic.ko changes the uniq to store the firmware version
to differentiate between 2 devices sharing the same PID. In the same
way, changing the device name is useful when the device export 3 nodes,
all with the same name.
Signed-off-by: Benjamin Tissoires <[email protected]>
---
changes in v3:
- amend for new WRITE_RANGE API
new in v2
---
drivers/hid/bpf/hid_bpf_struct_ops.c | 3 +++
include/linux/hid_bpf.h | 2 +-
2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/hid/bpf/hid_bpf_struct_ops.c b/drivers/hid/bpf/hid_bpf_struct_ops.c
index b14eccb121e0..e28cca78e1f5 100644
--- a/drivers/hid/bpf/hid_bpf_struct_ops.c
+++ b/drivers/hid/bpf/hid_bpf_struct_ops.c
@@ -74,6 +74,9 @@ static int hid_bpf_ops_btf_struct_access(struct bpf_verifier_log *log,
const struct hid_bpf_offset_write_range write_ranges[] = {
WRITE_RANGE(hid_bpf_ctx, retval, false),
+ WRITE_RANGE(hid_device, name, true),
+ WRITE_RANGE(hid_device, uniq, true),
+ WRITE_RANGE(hid_device, phys, true),
};
#undef WRITE_RANGE
const struct btf_type *state = NULL;
diff --git a/include/linux/hid_bpf.h b/include/linux/hid_bpf.h
index 1b4cc1b2c31d..65d7e0acc8c2 100644
--- a/include/linux/hid_bpf.h
+++ b/include/linux/hid_bpf.h
@@ -43,7 +43,7 @@ struct hid_device;
* ``hid`` and ``allocated_size`` are read-only, ``size`` and ``retval`` are read-write.
*/
struct hid_bpf_ctx {
- const struct hid_device *hid;
+ struct hid_device *hid;
__u32 allocated_size;
union {
__s32 retval;
--
2.44.0
Very mechanical:
- Change HID_BPF_DEVICE_EVENT and HID_BPF_RDESC_FIXUP #defines
- add a matching SEC(".struct_ops.link")
- in ArtistPro16Gen2 make the 2 functions static and have a new one
calling them
Signed-off-by: Benjamin Tissoires <[email protected]>
---
no changes in v3
no changes in v2
---
drivers/hid/bpf/progs/FR-TEC__Raptor-Mach-2.bpf.c | 5 +++++
drivers/hid/bpf/progs/HP__Elite-Presenter.bpf.c | 4 ++++
drivers/hid/bpf/progs/Huion__Kamvas-Pro-19.bpf.c | 5 +++++
.../hid/bpf/progs/IOGEAR__Kaliber-MMOmentum.bpf.c | 4 ++++
.../hid/bpf/progs/Microsoft__XBox-Elite-2.bpf.c | 4 ++++
drivers/hid/bpf/progs/Wacom__ArtPen.bpf.c | 4 ++++
drivers/hid/bpf/progs/XPPen__Artist24.bpf.c | 5 +++++
drivers/hid/bpf/progs/XPPen__ArtistPro16Gen2.bpf.c | 22 ++++++++++++++++++----
drivers/hid/bpf/progs/hid_bpf.h | 6 ++++--
9 files changed, 53 insertions(+), 6 deletions(-)
diff --git a/drivers/hid/bpf/progs/FR-TEC__Raptor-Mach-2.bpf.c b/drivers/hid/bpf/progs/FR-TEC__Raptor-Mach-2.bpf.c
index 2c2c1637ade8..caec91391d32 100644
--- a/drivers/hid/bpf/progs/FR-TEC__Raptor-Mach-2.bpf.c
+++ b/drivers/hid/bpf/progs/FR-TEC__Raptor-Mach-2.bpf.c
@@ -168,6 +168,11 @@ int BPF_PROG(raptor_mach_2_fix_hat_switch, struct hid_bpf_ctx *hctx)
return 0;
}
+HID_BPF_OPS(raptor_mach_2) = {
+ .hid_rdesc_fixup = (void *)hid_fix_rdesc_raptor_mach_2,
+ .hid_device_event = (void *)raptor_mach_2_fix_hat_switch,
+};
+
SEC("syscall")
int probe(struct hid_bpf_probe_args *ctx)
{
diff --git a/drivers/hid/bpf/progs/HP__Elite-Presenter.bpf.c b/drivers/hid/bpf/progs/HP__Elite-Presenter.bpf.c
index 17fc55f6f02c..c2413fa80543 100644
--- a/drivers/hid/bpf/progs/HP__Elite-Presenter.bpf.c
+++ b/drivers/hid/bpf/progs/HP__Elite-Presenter.bpf.c
@@ -45,6 +45,10 @@ int BPF_PROG(hid_fix_rdesc, struct hid_bpf_ctx *hctx)
return 0;
}
+HID_BPF_OPS(hp_elite_presenter) = {
+ .hid_rdesc_fixup = (void *)hid_fix_rdesc,
+};
+
SEC("syscall")
int probe(struct hid_bpf_probe_args *ctx)
{
diff --git a/drivers/hid/bpf/progs/Huion__Kamvas-Pro-19.bpf.c b/drivers/hid/bpf/progs/Huion__Kamvas-Pro-19.bpf.c
index 24b8a5aa05f3..a4a4f324aedd 100644
--- a/drivers/hid/bpf/progs/Huion__Kamvas-Pro-19.bpf.c
+++ b/drivers/hid/bpf/progs/Huion__Kamvas-Pro-19.bpf.c
@@ -255,6 +255,11 @@ int BPF_PROG(kamvas_pro_19_fix_3rd_button, struct hid_bpf_ctx *hctx)
return 0;
}
+HID_BPF_OPS(huion_Kamvas_pro_19) = {
+ .hid_rdesc_fixup = (void *)hid_fix_rdesc_huion_kamvas_pro_19,
+ .hid_device_event = (void *)kamvas_pro_19_fix_3rd_button,
+};
+
SEC("syscall")
int probe(struct hid_bpf_probe_args *ctx)
{
diff --git a/drivers/hid/bpf/progs/IOGEAR__Kaliber-MMOmentum.bpf.c b/drivers/hid/bpf/progs/IOGEAR__Kaliber-MMOmentum.bpf.c
index bee37872ee8c..82f1950445dd 100644
--- a/drivers/hid/bpf/progs/IOGEAR__Kaliber-MMOmentum.bpf.c
+++ b/drivers/hid/bpf/progs/IOGEAR__Kaliber-MMOmentum.bpf.c
@@ -45,6 +45,10 @@ int BPF_PROG(hid_fix_rdesc, struct hid_bpf_ctx *hctx)
return 0;
}
+HID_BPF_OPS(iogear_kaliber_momentum) = {
+ .hid_rdesc_fixup = (void *)hid_fix_rdesc,
+};
+
SEC("syscall")
int probe(struct hid_bpf_probe_args *ctx)
{
diff --git a/drivers/hid/bpf/progs/Microsoft__XBox-Elite-2.bpf.c b/drivers/hid/bpf/progs/Microsoft__XBox-Elite-2.bpf.c
index f9ad33f4a373..70b16edfb59a 100644
--- a/drivers/hid/bpf/progs/Microsoft__XBox-Elite-2.bpf.c
+++ b/drivers/hid/bpf/progs/Microsoft__XBox-Elite-2.bpf.c
@@ -114,6 +114,10 @@ int BPF_PROG(hid_fix_rdesc, struct hid_bpf_ctx *hctx)
return 0;
}
+HID_BPF_OPS(xbox_elite_2) = {
+ .hid_rdesc_fixup = (void *)hid_fix_rdesc,
+};
+
SEC("syscall")
int probe(struct hid_bpf_probe_args *ctx)
{
diff --git a/drivers/hid/bpf/progs/Wacom__ArtPen.bpf.c b/drivers/hid/bpf/progs/Wacom__ArtPen.bpf.c
index 39d77c5e9172..2da680bc4e11 100644
--- a/drivers/hid/bpf/progs/Wacom__ArtPen.bpf.c
+++ b/drivers/hid/bpf/progs/Wacom__ArtPen.bpf.c
@@ -139,6 +139,10 @@ int BPF_PROG(artpen_pressure_interpolate, struct hid_bpf_ctx *hctx)
return 0;
}
+HID_BPF_OPS(wacom_artpen) = {
+ .hid_device_event = (void *)artpen_pressure_interpolate,
+};
+
SEC("syscall")
int probe(struct hid_bpf_probe_args *ctx)
{
diff --git a/drivers/hid/bpf/progs/XPPen__Artist24.bpf.c b/drivers/hid/bpf/progs/XPPen__Artist24.bpf.c
index c938808bd589..bc0b85c38445 100644
--- a/drivers/hid/bpf/progs/XPPen__Artist24.bpf.c
+++ b/drivers/hid/bpf/progs/XPPen__Artist24.bpf.c
@@ -209,6 +209,11 @@ int BPF_PROG(xppen_24_fix_eraser, struct hid_bpf_ctx *hctx)
return 0;
}
+HID_BPF_OPS(xppen_artist_24) = {
+ .hid_rdesc_fixup = (void *)hid_fix_rdesc_xppen_artist24,
+ .hid_device_event = (void *)xppen_24_fix_eraser,
+};
+
SEC("syscall")
int probe(struct hid_bpf_probe_args *ctx)
{
diff --git a/drivers/hid/bpf/progs/XPPen__ArtistPro16Gen2.bpf.c b/drivers/hid/bpf/progs/XPPen__ArtistPro16Gen2.bpf.c
index 77ef8b95d52e..a669525691aa 100644
--- a/drivers/hid/bpf/progs/XPPen__ArtistPro16Gen2.bpf.c
+++ b/drivers/hid/bpf/progs/XPPen__ArtistPro16Gen2.bpf.c
@@ -105,8 +105,7 @@ int BPF_PROG(hid_fix_rdesc_xppen_artistpro16gen2, struct hid_bpf_ctx *hctx)
return sizeof(fixed_rdesc);
}
-SEC(HID_BPF_DEVICE_EVENT)
-int BPF_PROG(xppen_16_fix_eraser, struct hid_bpf_ctx *hctx)
+static int xppen_16_fix_eraser(struct hid_bpf_ctx *hctx)
{
__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 10 /* size */);
@@ -207,8 +206,7 @@ static void compensate_coordinates_by_tilt(__u8 *data, const __u8 idx,
data[idx+1] = coords >> 8;
}
-SEC(HID_BPF_DEVICE_EVENT)
-int BPF_PROG(xppen_16_fix_angle_offset, struct hid_bpf_ctx *hctx)
+static int xppen_16_fix_angle_offset(struct hid_bpf_ctx *hctx)
{
__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 10 /* size */);
@@ -254,6 +252,22 @@ int BPF_PROG(xppen_16_fix_angle_offset, struct hid_bpf_ctx *hctx)
return 0;
}
+SEC(HID_BPF_DEVICE_EVENT)
+int BPF_PROG(xppen_artist_pro_16_device_event, struct hid_bpf_ctx *hctx)
+{
+ int ret = xppen_16_fix_angle_offset(hctx);
+
+ if (ret)
+ return ret;
+
+ return xppen_16_fix_eraser(hctx);
+}
+
+HID_BPF_OPS(xppen_artist_pro_16) = {
+ .hid_rdesc_fixup = (void *)hid_fix_rdesc_xppen_artistpro16gen2,
+ .hid_device_event = (void *)xppen_artist_pro_16_device_event,
+};
+
SEC("syscall")
int probe(struct hid_bpf_probe_args *ctx)
{
diff --git a/drivers/hid/bpf/progs/hid_bpf.h b/drivers/hid/bpf/progs/hid_bpf.h
index 1970faf84310..8c1cd9e25bc3 100644
--- a/drivers/hid/bpf/progs/hid_bpf.h
+++ b/drivers/hid/bpf/progs/hid_bpf.h
@@ -5,8 +5,10 @@
#ifndef ____HID_BPF__H
#define ____HID_BPF__H
-#define HID_BPF_DEVICE_EVENT "fmod_ret/hid_bpf_device_event"
-#define HID_BPF_RDESC_FIXUP "fmod_ret/hid_bpf_rdesc_fixup"
+#define HID_BPF_DEVICE_EVENT "struct_ops/hid_device_event"
+#define HID_BPF_RDESC_FIXUP "struct_ops/hid_rdesc_fixup"
+#define HID_BPF_OPS(name) SEC(".struct_ops.link") \
+ struct hid_bpf_ops name
struct hid_bpf_probe_args {
unsigned int hid;
--
2.44.0
Now that we are using struct_ops, the docs need to be changed.
Signed-off-by: Benjamin Tissoires <[email protected]>
---
no changes in v3
changes in v2
- use BPF_F_BEFORE
---
Documentation/hid/hid-bpf.rst | 156 +++++++++++++++++++-----------------------
include/linux/hid_bpf.h | 8 +--
2 files changed, 76 insertions(+), 88 deletions(-)
diff --git a/Documentation/hid/hid-bpf.rst b/Documentation/hid/hid-bpf.rst
index 0765b3298ecf..456e15097d87 100644
--- a/Documentation/hid/hid-bpf.rst
+++ b/Documentation/hid/hid-bpf.rst
@@ -132,16 +132,17 @@ input events.
Available types of programs
===========================
-HID-BPF is built "on top" of BPF, meaning that we use tracing method to
+HID-BPF is built "on top" of BPF, meaning that we use bpf struct_ops method to
declare our programs.
HID-BPF has the following attachment types available:
-1. event processing/filtering with ``SEC("fmod_ret/hid_bpf_device_event")`` in libbpf
+1. event processing/filtering with ``SEC("struct_ops/hid_device_event")`` in libbpf
2. actions coming from userspace with ``SEC("syscall")`` in libbpf
-3. change of the report descriptor with ``SEC("fmod_ret/hid_bpf_rdesc_fixup")`` in libbpf
+3. change of the report descriptor with ``SEC("struct_ops/hid_rdesc_fixup")`` or
+ ``SEC("struct_ops.s/hid_rdesc_fixup")`` in libbpf
-A ``hid_bpf_device_event`` is calling a BPF program when an event is received from
+A ``hid_device_event`` is calling a BPF program when an event is received from
the device. Thus we are in IRQ context and can act on the data or notify userspace.
And given that we are in IRQ context, we can not talk back to the device.
@@ -149,37 +150,42 @@ A ``syscall`` means that userspace called the syscall ``BPF_PROG_RUN`` facility.
This time, we can do any operations allowed by HID-BPF, and talking to the device is
allowed.
-Last, ``hid_bpf_rdesc_fixup`` is different from the others as there can be only one
+Last, ``hid_rdesc_fixup`` is different from the others as there can be only one
BPF program of this type. This is called on ``probe`` from the driver and allows to
-change the report descriptor from the BPF program. Once a ``hid_bpf_rdesc_fixup``
+change the report descriptor from the BPF program. Once a ``hid_rdesc_fixup``
program has been loaded, it is not possible to overwrite it unless the program which
inserted it allows us by pinning the program and closing all of its fds pointing to it.
+Note that ``hid_rdesc_fixup`` can be declared as sleepable (``SEC("struct_ops.s/hid_rdesc_fixup")``).
+
+
Developer API:
==============
-User API data structures available in programs:
------------------------------------------------
+Available ``struct_ops`` for HID-BPF:
+-------------------------------------
.. kernel-doc:: include/linux/hid_bpf.h
+ :identifiers: hid_bpf_ops
-Available tracing functions to attach a HID-BPF program:
---------------------------------------------------------
-.. kernel-doc:: drivers/hid/bpf/hid_bpf_dispatch.c
- :functions: hid_bpf_device_event hid_bpf_rdesc_fixup
+User API data structures available in programs:
+-----------------------------------------------
+
+.. kernel-doc:: include/linux/hid_bpf.h
+ :identifiers: hid_bpf_ctx
-Available API that can be used in all HID-BPF programs:
--------------------------------------------------------
+Available API that can be used in all HID-BPF struct_ops programs:
+------------------------------------------------------------------
.. kernel-doc:: drivers/hid/bpf/hid_bpf_dispatch.c
- :functions: hid_bpf_get_data
+ :identifiers: hid_bpf_get_data
-Available API that can be used in syscall HID-BPF programs:
------------------------------------------------------------
+Available API that can be used in syscall HID-BPF programs or in sleepable HID-BPF struct_ops programs:
+-------------------------------------------------------------------------------------------------------
.. kernel-doc:: drivers/hid/bpf/hid_bpf_dispatch.c
- :functions: hid_bpf_attach_prog hid_bpf_hw_request hid_bpf_hw_output_report hid_bpf_input_report hid_bpf_allocate_context hid_bpf_release_context
+ :identifiers: hid_bpf_hw_request hid_bpf_hw_output_report hid_bpf_input_report hid_bpf_allocate_context hid_bpf_release_context
General overview of a HID-BPF program
=====================================
@@ -222,20 +228,21 @@ This allows the following:
Effect of a HID-BPF program
---------------------------
-For all HID-BPF attachment types except for :c:func:`hid_bpf_rdesc_fixup`, several eBPF
-programs can be attached to the same device.
+For all HID-BPF attachment types except for :c:func:`hid_rdesc_fixup`, several eBPF
+programs can be attached to the same device. If a HID-BPF struct_ops has a
+:c:func:`hid_rdesc_fixup` while another is already attached to the device, the
+kernel will return `-EINVAL` when attaching the struct_ops.
-Unless ``HID_BPF_FLAG_INSERT_HEAD`` is added to the flags while attaching the
-program, the new program is appended at the end of the list.
-``HID_BPF_FLAG_INSERT_HEAD`` will insert the new program at the beginning of the
-list which is useful for e.g. tracing where we need to get the unprocessed events
-from the device.
+Unless ``BPF_F_BEFORE`` is added to the flags while attaching the program, the new
+program is appended at the end of the list.
+``BPF_F_BEFORE`` will insert the new program at the beginning of the list which is
+useful for e.g. tracing where we need to get the unprocessed events from the device.
-Note that if there are multiple programs using the ``HID_BPF_FLAG_INSERT_HEAD`` flag,
+Note that if there are multiple programs using the ``BPF_F_BEFORE`` flag,
only the most recently loaded one is actually the first in the list.
-``SEC("fmod_ret/hid_bpf_device_event")``
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+``SEC("struct_ops/hid_device_event")``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Whenever a matching event is raised, the eBPF programs are called one after the other
and are working on the same data buffer.
@@ -258,17 +265,17 @@ with, userspace needs to refer to the device by its unique system id (the last 4
in the sysfs path: ``/sys/bus/hid/devices/xxxx:yyyy:zzzz:0000``).
To retrieve a context associated with the device, the program must call
-:c:func:`hid_bpf_allocate_context` and must release it with :c:func:`hid_bpf_release_context`
+hid_bpf_allocate_context() and must release it with hid_bpf_release_context()
before returning.
Once the context is retrieved, one can also request a pointer to kernel memory with
-:c:func:`hid_bpf_get_data`. This memory is big enough to support all input/output/feature
+hid_bpf_get_data(). This memory is big enough to support all input/output/feature
reports of the given device.
-``SEC("fmod_ret/hid_bpf_rdesc_fixup")``
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+``SEC("struct_ops/hid_rdesc_fixup")``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-The ``hid_bpf_rdesc_fixup`` program works in a similar manner to
-``.report_fixup`` of ``struct hid_driver``.
+The ``hid_rdesc_fixup`` program works in a similar manner to ``.report_fixup``
+of ``struct hid_driver``.
When the device is probed, the kernel sets the data buffer of the context with the
content of the report descriptor. The memory associated with that buffer is
@@ -277,33 +284,31 @@ content of the report descriptor. The memory associated with that buffer is
The eBPF program can modify the data buffer at-will and the kernel uses the
modified content and size as the report descriptor.
-Whenever a ``SEC("fmod_ret/hid_bpf_rdesc_fixup")`` program is attached (if no
-program was attached before), the kernel immediately disconnects the HID device
-and does a reprobe.
+Whenever a struct_ops containing a ``SEC("struct_ops/hid_rdesc_fixup")`` program
+is attached (if no program was attached before), the kernel immediately disconnects
+the HID device and does a reprobe.
-In the same way, when the ``SEC("fmod_ret/hid_bpf_rdesc_fixup")`` program is
-detached, the kernel issues a disconnect on the device.
+In the same way, when this struct_ops is detached, the kernel issues a disconnect
+on the device.
There is no ``detach`` facility in HID-BPF. Detaching a program happens when
-all the user space file descriptors pointing at a program are closed.
+all the user space file descriptors pointing at a HID-BPF struct_ops link are closed.
Thus, if we need to replace a report descriptor fixup, some cooperation is
required from the owner of the original report descriptor fixup.
-The previous owner will likely pin the program in the bpffs, and we can then
+The previous owner will likely pin the struct_ops link in the bpffs, and we can then
replace it through normal bpf operations.
Attaching a bpf program to a device
===================================
-``libbpf`` does not export any helper to attach a HID-BPF program.
-Users need to use a dedicated ``syscall`` program which will call
-``hid_bpf_attach_prog(hid_id, program_fd, flags)``.
+We now use standard struct_ops attachment through ``bpf_map__attach_struct_ops()``.
+But given that we need to attach a struct_ops to a dedicated HID device, the caller
+must set ``hid_id`` in the struct_ops map before loading the program in the kernel.
``hid_id`` is the unique system ID of the HID device (the last 4 numbers in the
sysfs path: ``/sys/bus/hid/devices/xxxx:yyyy:zzzz:0000``)
-``progam_fd`` is the opened file descriptor of the program to attach.
-
-``flags`` is of type ``enum hid_bpf_attach_flags``.
+One can also set ``flags``, which is of type ``enum hid_bpf_attach_flags``.
We can not rely on hidraw to bind a BPF program to a HID device. hidraw is an
artefact of the processing of the HID device, and is not stable. Some drivers
@@ -358,32 +363,15 @@ For that, we can create a basic skeleton for our BPF program::
extern __u8 *hid_bpf_get_data(struct hid_bpf_ctx *ctx,
unsigned int offset,
const size_t __sz) __ksym;
- extern int hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, u32 flags) __ksym;
struct {
__uint(type, BPF_MAP_TYPE_RINGBUF);
__uint(max_entries, 4096 * 64);
} ringbuf SEC(".maps");
- struct attach_prog_args {
- int prog_fd;
- unsigned int hid;
- unsigned int flags;
- int retval;
- };
-
- SEC("syscall")
- int attach_prog(struct attach_prog_args *ctx)
- {
- ctx->retval = hid_bpf_attach_prog(ctx->hid,
- ctx->prog_fd,
- ctx->flags);
- return 0;
- }
-
__u8 current_value = 0;
- SEC("?fmod_ret/hid_bpf_device_event")
+ SEC("struct_ops/hid_device_event")
int BPF_PROG(filter_switch, struct hid_bpf_ctx *hid_ctx)
{
__u8 *data = hid_bpf_get_data(hid_ctx, 0 /* offset */, 192 /* size */);
@@ -407,37 +395,37 @@ For that, we can create a basic skeleton for our BPF program::
return 0;
}
-To attach ``filter_switch``, userspace needs to call the ``attach_prog`` syscall
-program first::
+ SEC(".struct_ops.link")
+ struct hid_bpf_ops haptic_tablet = {
+ .hid_device_event = (void *)filter_switch,
+ };
+
+
+To attach ``haptic_tablet``, userspace needs to set ``hid_id`` first::
static int attach_filter(struct hid *hid_skel, int hid_id)
{
- int err, prog_fd;
- int ret = -1;
- struct attach_prog_args args = {
- .hid = hid_id,
- };
- DECLARE_LIBBPF_OPTS(bpf_test_run_opts, tattrs,
- .ctx_in = &args,
- .ctx_size_in = sizeof(args),
- );
+ int err, link_fd;
- args.prog_fd = bpf_program__fd(hid_skel->progs.filter_switch);
+ hid_skel->struct_ops.haptic_tablet->hid_id = hid_id;
+ err = hid__load(skel);
+ if (err)
+ return err;
- prog_fd = bpf_program__fd(hid_skel->progs.attach_prog);
-
- err = bpf_prog_test_run_opts(prog_fd, &tattrs);
- if (err)
- return err;
+ link_fd = bpf_map__attach_struct_ops(hid_skel->maps.haptic_tablet);
+ if (!link_fd) {
+ fprintf(stderr, "can not attach HID-BPF program: %m\n");
+ return -1;
+ }
- return args.retval; /* the fd of the created bpf_link */
+ return link_fd; /* the fd of the created bpf_link */
}
Our userspace program can now listen to notifications on the ring buffer, and
is awaken only when the value changes.
When the userspace program doesn't need to listen to events anymore, it can just
-close the returned fd from :c:func:`attach_filter`, which will tell the kernel to
+close the returned bpf link from :c:func:`attach_filter`, which will tell the kernel to
detach the program from the HID device.
Of course, in other use cases, the userspace program can also pin the fd to the
diff --git a/include/linux/hid_bpf.h b/include/linux/hid_bpf.h
index 447b94aa99ab..1b4cc1b2c31d 100644
--- a/include/linux/hid_bpf.h
+++ b/include/linux/hid_bpf.h
@@ -20,11 +20,9 @@ struct hid_device;
* struct hid_bpf_ctx - User accessible data for all HID programs
*
* ``data`` is not directly accessible from the context. We need to issue
- * a call to ``hid_bpf_get_data()`` in order to get a pointer to that field.
+ * a call to hid_bpf_get_data() in order to get a pointer to that field.
*
- * All of these fields are currently read-only.
- *
- * @hid: the ``struct hid_device`` representing the device itself
+ * @hid: the &struct hid_device representing the device itself
* @allocated_size: Allocated size of data.
*
* This is how much memory is available and can be requested
@@ -41,6 +39,8 @@ struct hid_device;
* ``size`` must always be less or equal than ``allocated_size`` (it is enforced
* once all BPF programs have been run).
* @retval: Return value of the previous program.
+ *
+ * ``hid`` and ``allocated_size`` are read-only, ``size`` and ``retval`` are read-write.
*/
struct hid_bpf_ctx {
const struct hid_device *hid;
--
2.44.0
warning: unused variable ‘tilt’ [-Wunused-variable]
Signed-off-by: Peter Hutterer <[email protected]>
Signed-off-by: Benjamin Tissoires <[email protected]>
---
no changes in v3
no changes in v2
---
drivers/hid/bpf/progs/XPPen__Artist24.bpf.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/drivers/hid/bpf/progs/XPPen__Artist24.bpf.c b/drivers/hid/bpf/progs/XPPen__Artist24.bpf.c
index bc0b85c38445..d4d062c3a653 100644
--- a/drivers/hid/bpf/progs/XPPen__Artist24.bpf.c
+++ b/drivers/hid/bpf/progs/XPPen__Artist24.bpf.c
@@ -158,7 +158,6 @@ int BPF_PROG(xppen_24_fix_eraser, struct hid_bpf_ctx *hctx)
__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 10 /* size */);
__u8 current_state, changed_state;
bool prev_tip;
- __u16 tilt;
if (!data)
return 0; /* EPERM check */
--
2.44.0
On Sat, Jun 8, 2024 at 2:01 AM Benjamin Tissoires <[email protected]> wrote:
>
> The idea is to provide a list of stucts and their editable fields.
>
> Currently no functional changes are introduced here, we will add some
> more writeable fields in the next patch.
>
> Signed-off-by: Benjamin Tissoires <[email protected]>
>
> ---
>
> changes in v3:
> - rewrote WRITE_RANGE macro to not deal with offset from the caller side
>
> new in v2
> ---
> drivers/hid/bpf/hid_bpf_struct_ops.c | 91 +++++++++++++++++++++++++++---------
> 1 file changed, 69 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/hid/bpf/hid_bpf_struct_ops.c b/drivers/hid/bpf/hid_bpf_struct_ops.c
> index 056d05d96962..b14eccb121e0 100644
> --- a/drivers/hid/bpf/hid_bpf_struct_ops.c
> +++ b/drivers/hid/bpf/hid_bpf_struct_ops.c
> @@ -16,6 +16,7 @@
> #include <linux/hid_bpf.h>
> #include <linux/init.h>
> #include <linux/module.h>
> +#include <linux/stddef.h>
> #include <linux/workqueue.h>
> #include "hid_bpf_dispatch.h"
>
> @@ -52,40 +53,86 @@ static int hid_bpf_ops_check_member(const struct btf_type *t,
> return 0;
> }
>
> +struct hid_bpf_offset_write_range {
> + const char *struct_name;
> + u32 struct_length;
> + u32 start;
> + u32 end;
> +};
> +
> static int hid_bpf_ops_btf_struct_access(struct bpf_verifier_log *log,
> const struct bpf_reg_state *reg,
> int off, int size)
> {
> - const struct btf_type *state;
> - const struct btf_type *t;
> - s32 type_id;
> +#define WRITE_RANGE(_name, _field, _is_string) \
> + { \
> + .struct_name = #_name, \
> + .struct_length = sizeof(struct _name), \
> + .start = offsetof(struct _name, _field), \
> + .end = offsetofend(struct _name, _field) - !!(_is_string),
so it works because char name[128]; had last byte as zero
before prog writes into it (in addition to potentially having
earlier 0 bytes), so the string is guaranteed
to be null-terminated regardless of what prog writes into it.
Right?
Overall:
Acked-by: Alexei Starovoitov <[email protected]>
On Jun 10 2024, Alexei Starovoitov wrote:
> On Sat, Jun 8, 2024 at 2:01 AM Benjamin Tissoires <[email protected]> wrote:
> >
> > The idea is to provide a list of stucts and their editable fields.
> >
> > Currently no functional changes are introduced here, we will add some
> > more writeable fields in the next patch.
> >
> > Signed-off-by: Benjamin Tissoires <[email protected]>
> >
> > ---
> >
> > changes in v3:
> > - rewrote WRITE_RANGE macro to not deal with offset from the caller side
> >
> > new in v2
> > ---
> > drivers/hid/bpf/hid_bpf_struct_ops.c | 91 +++++++++++++++++++++++++++---------
> > 1 file changed, 69 insertions(+), 22 deletions(-)
> >
> > diff --git a/drivers/hid/bpf/hid_bpf_struct_ops.c b/drivers/hid/bpf/hid_bpf_struct_ops.c
> > index 056d05d96962..b14eccb121e0 100644
> > --- a/drivers/hid/bpf/hid_bpf_struct_ops.c
> > +++ b/drivers/hid/bpf/hid_bpf_struct_ops.c
> > @@ -16,6 +16,7 @@
> > #include <linux/hid_bpf.h>
> > #include <linux/init.h>
> > #include <linux/module.h>
> > +#include <linux/stddef.h>
> > #include <linux/workqueue.h>
> > #include "hid_bpf_dispatch.h"
> >
> > @@ -52,40 +53,86 @@ static int hid_bpf_ops_check_member(const struct btf_type *t,
> > return 0;
> > }
> >
> > +struct hid_bpf_offset_write_range {
> > + const char *struct_name;
> > + u32 struct_length;
> > + u32 start;
> > + u32 end;
> > +};
> > +
> > static int hid_bpf_ops_btf_struct_access(struct bpf_verifier_log *log,
> > const struct bpf_reg_state *reg,
> > int off, int size)
> > {
> > - const struct btf_type *state;
> > - const struct btf_type *t;
> > - s32 type_id;
> > +#define WRITE_RANGE(_name, _field, _is_string) \
> > + { \
> > + .struct_name = #_name, \
> > + .struct_length = sizeof(struct _name), \
> > + .start = offsetof(struct _name, _field), \
> > + .end = offsetofend(struct _name, _field) - !!(_is_string),
>
> so it works because char name[128]; had last byte as zero
> before prog writes into it (in addition to potentially having
> earlier 0 bytes), so the string is guaranteed
> to be null-terminated regardless of what prog writes into it.
> Right?
Yeah, struct hid_device is created through hid_allocate_device(), which
does a kzalloc. Then all operations are supposedly safe in the current
transport layers, so the last byte should always be \0.
>
> Overall:
> Acked-by: Alexei Starovoitov <[email protected]>
Thanks a lot.
I might send a v4 or not depending if I get other reviews, but I'll make
sure to take your nitpick in 3/16 into account (cast kdata/udate in the
beginning of the function to make the lines shorter and less verbose).
Cheers,
Benjamin
On Sat, 08 Jun 2024 11:01:12 +0200, Benjamin Tissoires wrote:
> The purpose of this series is to rethink how HID-BPF is invoked.
> Currently it implies a jmp table, a prog fd bpf_map, a preloaded tracing
> bpf program and a lot of manual work for handling the bpf program
> lifetime and addition/removal.
>
> OTOH, bpf_struct_ops take care of most of the bpf handling leaving us
> with a simple list of ops pointers, and we can directly call the
> struct_ops program from the kernel as a regular function.
>
> [...]
Applied to hid/hid.git (for-6.11/bpf), thanks!
[01/16] HID: rename struct hid_bpf_ops into hid_ops
https://git.kernel.org/hid/hid/c/146a06a0d225
[02/16] HID: bpf: add hid_get/put_device() helpers
https://git.kernel.org/hid/hid/c/99b40bf8053f
[03/16] HID: bpf: implement HID-BPF through bpf_struct_ops
https://git.kernel.org/hid/hid/c/ebc0d8093e8c
[04/16] selftests/hid: convert the hid_bpf selftests with struct_ops
https://git.kernel.org/hid/hid/c/d7696738d66b
[05/16] HID: samples: convert the 2 HID-BPF samples into struct_ops
https://git.kernel.org/hid/hid/c/e342d6f6f7d8
[06/16] HID: bpf: add defines for HID-BPF SEC in in-tree bpf fixes
https://git.kernel.org/hid/hid/c/df67602fb8d5
[07/16] HID: bpf: convert in-tree fixes into struct_ops
https://git.kernel.org/hid/hid/c/50fe0fc6e206
[08/16] HID: bpf: remove tracing HID-BPF capability
https://git.kernel.org/hid/hid/c/4a86220e046d
[09/16] selftests/hid: add subprog call test
https://git.kernel.org/hid/hid/c/05b3b8f19441
[10/16] Documentation: HID: amend HID-BPF for struct_ops
https://git.kernel.org/hid/hid/c/c5958697a5fa
[11/16] Documentation: HID: add a small blurb on udev-hid-bpf
https://git.kernel.org/hid/hid/c/5f42e19de53f
[12/16] HID: bpf: Artist24: remove unused variable
https://git.kernel.org/hid/hid/c/26ba1e0a982b
[13/16] HID: bpf: error on warnings when compiling bpf objects
https://git.kernel.org/hid/hid/c/c94ae2189aca
[14/16] bpf: allow bpf helpers to be used into HID-BPF struct_ops
https://git.kernel.org/hid/hid/c/bd0747543b3d
[15/16] HID: bpf: rework hid_bpf_ops_btf_struct_access
https://git.kernel.org/hid/hid/c/f1a5fb6c7cf6
[16/16] HID: bpf: make part of struct hid_device writable
https://git.kernel.org/hid/hid/c/33c0fb85b571
Cheers,
--
Benjamin Tissoires <[email protected]>