Hi Benjamin,
On 04/03/2022 19:28, Benjamin Tissoires wrote:
Now that BPF can be compatible with HID, add the capability into HID.
drivers/hid/hid-bpf.c takes care of the glue between bpf and HID, and
hid-core can then inject any incoming event from the device into a BPF
program to filter/analyze it.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
---
changes in v2:
- split the series by bpf/libbpf/hid/selftests and samples
- addressed review comments from v1
---
drivers/hid/Makefile | 1 +
drivers/hid/hid-bpf.c | 157 +++++++++++++++++++++++++++++++++++++++++
drivers/hid/hid-core.c | 21 +++++-
include/linux/hid.h | 11 +++
4 files changed, 187 insertions(+), 3 deletions(-)
create mode 100644 drivers/hid/hid-bpf.c
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index 6d3e630e81af..08d2d7619937 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -4,6 +4,7 @@
#
hid-y := hid-core.o hid-input.o hid-quirks.o
hid-$(CONFIG_DEBUG_FS) += hid-debug.o
+hid-$(CONFIG_BPF) += hid-bpf.o
obj-$(CONFIG_HID) += hid.o
obj-$(CONFIG_UHID) += uhid.o
diff --git a/drivers/hid/hid-bpf.c b/drivers/hid/hid-bpf.c
new file mode 100644
index 000000000000..8120e598de9f
--- /dev/null
+++ b/drivers/hid/hid-bpf.c
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * BPF in HID support for Linux
+ *
+ * Copyright (c) 2022 Benjamin Tissoires
+ */
+
+#include <linux/filter.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+
+#include <uapi/linux/bpf_hid.h>
+#include <linux/hid.h>
+
+static int __hid_bpf_match_sysfs(struct device *dev, const void *data)
+{
+ struct kernfs_node *kn = dev->kobj.sd;
+ struct kernfs_node *uevent_kn;
+
+ uevent_kn = kernfs_find_and_get_ns(kn, "uevent", NULL);
+
+ return uevent_kn == data;
+}
+
+static struct hid_device *hid_bpf_fd_to_hdev(int fd)
+{
+ struct device *dev;
+ struct hid_device *hdev;
+ struct fd f = fdget(fd);
+ struct inode *inode;
+ struct kernfs_node *node;
+
+ if (!f.file) {
+ hdev = ERR_PTR(-EBADF);
+ goto out;
+ }
+
+ inode = file_inode(f.file);
+ node = inode->i_private;
+
+ dev = bus_find_device(&hid_bus_type, NULL, node, __hid_bpf_match_sysfs);
+
+ if (dev)
+ hdev = to_hid_device(dev);
+ else
+ hdev = ERR_PTR(-EINVAL);
+
+ out:
+ fdput(f);
+ return hdev;
+}
+
+static int hid_bpf_link_attach(struct hid_device *hdev, enum bpf_hid_attach_type type)
+{
+ int err = 0;
+
+ switch (type) {
+ case BPF_HID_ATTACH_DEVICE_EVENT:
+ if (!hdev->bpf.ctx) {
+ hdev->bpf.ctx = bpf_hid_allocate_ctx(hdev, HID_BPF_MAX_BUFFER_SIZE);
+ if (IS_ERR(hdev->bpf.ctx)) {
+ err = PTR_ERR(hdev->bpf.ctx);
+ hdev->bpf.ctx = NULL;
+ }
+ }
+ break;
+ default:
+ /* do nothing */
These cause following error:
CC drivers/hid/hid-bpf.o
drivers/hid/hid-bpf.c: In function ‘hid_bpf_link_attach’:
drivers/hid/hid-bpf.c:88:2: error: label at end of compound statement
88 | default:
| ^~~~~~~
drivers/hid/hid-bpf.c: In function ‘hid_bpf_link_attached’:
drivers/hid/hid-bpf.c:101:2: error: label at end of compound statement
101 | default:
| ^~~~~~~
drivers/hid/hid-bpf.c: In function ‘hid_bpf_array_detached’:
drivers/hid/hid-bpf.c:116:2: error: label at end of compound statement
116 | default:
| ^~~~~~~
make[2]: *** [scripts/Makefile.build:288: drivers/hid/hid-bpf.o] Error 1
make[1]: *** [scripts/Makefile.build:550: drivers/hid] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:1831: drivers] Error 2
To fix that, you need to add a break statement at end:
default:
/* do nothing */
break;
Same for couple of other occurrences in the file.
-Tero
