[PATCH bpf-next v2 02/28] bpf: introduce hid program type

Benjamin Tissoires
2022-03-04T17:31:05Z

HID is a protocol that could benefit from using BPF too.

This patch implements a net-like use of BPF capability for HID.
Any incoming report coming from the device can be injected into a series
of BPF programs that can modify it or even discard it by setting the
size in the context to 0.

The kernel/bpf implementation is based on net-namespace.c, with only
the bpf_link part kept, there is no real points in keeping the
bpf_prog_{attach|detach} API.

The implementation here is only focusing on the bpf changes. The HID
changes that hooks onto this are coming in a separate patch.

Given that HID can be compiled in as a module, and the functions that
kernel/bpf/hid.c needs to call in hid.ko are exported in struct hid_hooks.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

---

changes in v2:
- split the series by bpf/libbpf/hid/selftests and samples
- unsigned long -> __u16 in uapi/linux/bpf_hid.h
- change the bpf_ctx to be of variable size, with a min of 1024 bytes
- make this 1 kB available directly from bpf program, the rest will
need a helper
- add some more doc comments in uapi
---
include/linux/bpf-hid.h | 108 ++++++++
include/linux/bpf_types.h | 4 +
include/linux/hid.h | 5 +
include/uapi/linux/bpf.h | 7 +
include/uapi/linux/bpf_hid.h | 39 +++
kernel/bpf/Makefile | 3 +
kernel/bpf/hid.c | 437 +++++++++++++++++++++++++++++++++
kernel/bpf/syscall.c | 8 +
tools/include/uapi/linux/bpf.h | 7 +
9 files changed, 618 insertions(+)
create mode 100644 include/linux/bpf-hid.h
create mode 100644 include/uapi/linux/bpf_hid.h
create mode 100644 kernel/bpf/hid.c

diff --git a/include/linux/bpf-hid.h b/include/linux/bpf-hid.h
new file mode 100644
index 000000000000..3cda78051b5f
--- /dev/null
+++ b/include/linux/bpf-hid.h
@@ -0,0 +1,108 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BPF_HID_H
+#define _BPF_HID_H
+
+#include <linux/mutex.h>
+#include <uapi/linux/bpf.h>
+#include <uapi/linux/bpf_hid.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+
+struct bpf_prog;
+struct bpf_prog_array;
+struct hid_device;
+
+enum bpf_hid_attach_type {
+ BPF_HID_ATTACH_INVALID = -1,
+ BPF_HID_ATTACH_DEVICE_EVENT = 0,
+ MAX_BPF_HID_ATTACH_TYPE
+};
+
+struct bpf_hid {
+ struct hid_bpf_ctx *ctx;
+
+ /* Array of programs to run compiled from links */
+ struct bpf_prog_array __rcu *run_array[MAX_BPF_HID_ATTACH_TYPE];
+ struct list_head links[MAX_BPF_HID_ATTACH_TYPE];
+};
+
+static inline enum bpf_hid_attach_type
+to_bpf_hid_attach_type(enum bpf_attach_type attach_type)
+{
+ switch (attach_type) {
+ case BPF_HID_DEVICE_EVENT:
+ return BPF_HID_ATTACH_DEVICE_EVENT;
+ default:
+ return BPF_HID_ATTACH_INVALID;
+ }
+}
+
+static inline struct hid_bpf_ctx *bpf_hid_allocate_ctx(struct hid_device *hdev,
+ size_t data_size)
+{
+ struct hid_bpf_ctx *ctx;
+
+ /* ensure data_size is between min and max */
+ data_size = clamp_val(data_size,
+ HID_BPF_MIN_BUFFER_SIZE,
+ HID_BPF_MAX_BUFFER_SIZE);
+
+ ctx = kzalloc(sizeof(*ctx) + data_size, GFP_KERNEL);
+ if (!ctx)
+ return ERR_PTR(-ENOMEM);
+
+ ctx->hdev = hdev;
+ ctx->allocated_size = data_size;
+
+ return ctx;
+}
+
+union bpf_attr;
+struct bpf_prog;
+
+#if IS_ENABLED(CONFIG_HID)
+int bpf_hid_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr);
+int bpf_hid_link_create(const union bpf_attr *attr,
+ struct bpf_prog *prog);
+#else
+static inline int bpf_hid_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline int bpf_hid_link_create(const union bpf_attr *attr,
+ struct bpf_prog *prog)
+{
+ return -EOPNOTSUPP;
+}
+#endif
+
+static inline bool bpf_hid_link_empty(struct bpf_hid *bpf,
+ enum bpf_hid_attach_type type)
+{
+ return list_empty(&bpf->links[type]);
+}
+
+struct bpf_hid_hooks {
+ struct hid_device *(*hdev_from_fd)(int fd);
+ int (*link_attach)(struct hid_device *hdev, enum bpf_hid_attach_type type);
+ void (*array_detached)(struct hid_device *hdev, enum bpf_hid_attach_type type);
+};
+
+#ifdef CONFIG_BPF
+int bpf_hid_init(struct hid_device *hdev);
+void bpf_hid_exit(struct hid_device *hdev);
+void bpf_hid_set_hooks(struct bpf_hid_hooks *hooks);
+#else
+static inline int bpf_hid_init(struct hid_device *hdev)
+{
+ return 0;
+}
+
+static inline void bpf_hid_exit(struct hid_device *hdev) {}
+static inline void bpf_hid_set_hooks(struct bpf_hid_hooks *hooks) {}
+#endif
+
+#endif /* _BPF_HID_H */
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index 48a91c51c015..1509862aacc4 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -76,6 +76,10 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_EXT, bpf_extension,
BPF_PROG_TYPE(BPF_PROG_TYPE_LSM, lsm,
void *, void *)
#endif /* CONFIG_BPF_LSM */
+#if IS_ENABLED(CONFIG_HID)
+BPF_PROG_TYPE(BPF_PROG_TYPE_HID, hid,
+ __u32, u32)
+#endif
#endif
BPF_PROG_TYPE(BPF_PROG_TYPE_SYSCALL, bpf_syscall,
void *, void *)
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 7487b0586fe6..56f6f4ad45a7 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -15,6 +15,7 @@

#include <linux/bitops.h>
+#include <linux/bpf-hid.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/list.h>
@@ -639,6 +640,10 @@ struct hid_device { /* device report descriptor */
struct list_head debug_list;
spinlock_t debug_list_lock;
wait_queue_head_t debug_wait;
+
+#ifdef CONFIG_BPF
+ struct bpf_hid bpf;
+#endif
};

#define to_hid_device(pdev) \
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index afe3d0d7f5f2..5978b92cacd3 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -952,6 +952,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_LSM,
BPF_PROG_TYPE_SK_LOOKUP,
BPF_PROG_TYPE_SYSCALL, /* a program that can execute syscalls */
+ BPF_PROG_TYPE_HID,
};

enum bpf_attach_type {
@@ -997,6 +998,7 @@ enum bpf_attach_type {
BPF_SK_REUSEPORT_SELECT,
BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
BPF_PERF_EVENT,
+ BPF_HID_DEVICE_EVENT,
__MAX_BPF_ATTACH_TYPE
};

@@ -1011,6 +1013,7 @@ enum bpf_link_type {
BPF_LINK_TYPE_NETNS = 5,
BPF_LINK_TYPE_XDP = 6,
BPF_LINK_TYPE_PERF_EVENT = 7,
+ BPF_LINK_TYPE_HID = 8,

MAX_BPF_LINK_TYPE,
};
@@ -5870,6 +5873,10 @@ struct bpf_link_info {
struct {
__u32 ifindex;
} xdp;
+ struct {
+ __s32 hidraw_ino;
+ __u32 attach_type;
+ } hid;
};
} __attribute__((aligned(8)));

diff --git a/include/uapi/linux/bpf_hid.h b/include/uapi/linux/bpf_hid.h
new file mode 100644
index 000000000000..975ca5bd526f
--- /dev/null
+++ b/include/uapi/linux/bpf_hid.h
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later WITH Linux-syscall-note */
+
+/*
+ * HID BPF public headers
+ *
+ * Copyright (c) 2021 Benjamin Tissoires
+ */
+
+#ifndef _UAPI__LINUX_BPF_HID_H__
+#define _UAPI__LINUX_BPF_HID_H__
+
+#include <linux/types.h>
+
+/*
+ * The first 1024 bytes are available directly in the bpf programs.
+ * To access the rest of the data (if allocated_size is bigger
+ * than 1024, you need to use bpf_hid_ helpers.
+ */
+#define HID_BPF_MIN_BUFFER_SIZE 1024
+#define HID_BPF_MAX_BUFFER_SIZE 16384 /* in sync with HID_MAX_BUFFER_SIZE */
+
+struct hid_device;
+
+enum hid_bpf_event {
+ HID_BPF_UNDEF = 0,
+ HID_BPF_DEVICE_EVENT, /* when attach type is BPF_HID_DEVICE_EVENT */
+};
+
+struct hid_bpf_ctx {
+ enum hid_bpf_event type; /* read-only */
+ __u16 allocated_size; /* the allocated size of data below (RO) */
+ struct hid_device *hdev; /* read-only */
+
+ __u16 size; /* used size in data (RW) */
+ __u8 data[]; /* data buffer (RW) */
+};
+
+#endif /* _UAPI__LINUX_BPF_HID_H__ */
+
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index c1a9be6a4b9f..8d5619d3d7e5 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -35,6 +35,9 @@ ifeq ($(CONFIG_BPF_JIT),y)
obj-$(CONFIG_BPF_SYSCALL) += bpf_struct_ops.o
obj-${CONFIG_BPF_LSM} += bpf_lsm.o
endif
+ifneq ($(CONFIG_HID),)
+obj-$(CONFIG_BPF_SYSCALL) += hid.o
+endif
obj-$(CONFIG_BPF_PRELOAD) += preload/

obj-$(CONFIG_BPF_SYSCALL) += relo_core.o
diff --git a/kernel/bpf/hid.c b/kernel/bpf/hid.c
new file mode 100644
index 000000000000..db7f75a0a812
--- /dev/null
+++ b/kernel/bpf/hid.c
@@ -0,0 +1,437 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * based on kernel/bpf/net-namespace.c
+ */
+
+#include <linux/bpf.h>
+#include <linux/bpf-hid.h>
+#include <linux/filter.h>
+#include <linux/hid.h>
+#include <linux/hidraw.h>
+
+/*
+ * Functions to manage BPF programs attached to hid
+ */
+
+struct bpf_hid_link {
+ struct bpf_link link;
+ enum bpf_attach_type type;
+ enum bpf_hid_attach_type hid_type;
+
+ /* Must be accessed with bpf_hid_mutex held. */
+ struct hid_device *hdev;
+ struct list_head node; /* node in list of links attached to hid */
+};
+
+/* Protects updates to bpf_hid */
+DEFINE_MUTEX(bpf_hid_mutex);
+
+static struct bpf_hid_hooks hid_hooks = {0};
+
+void bpf_hid_set_hooks(struct bpf_hid_hooks *hooks)
+{
+ if (hooks)
+ hid_hooks = *hooks;
+ else
+ memset(&hid_hooks, 0, sizeof(hid_hooks));
+}
+EXPORT_SYMBOL_GPL(bpf_hid_set_hooks);
+
+static const struct bpf_func_proto *
+hid_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
+{
+ switch (func_id) {
+ default:
+ return bpf_base_func_proto(func_id);
+ }
+}
+
+static bool hid_is_valid_access(int off, int size,
+ enum bpf_access_type access_type,
+ const struct bpf_prog *prog,
+ struct bpf_insn_access_aux *info)
+{
+ /* everything not in ctx is prohibited */
+ if (off < 0 || off + size > sizeof(struct hid_bpf_ctx) + HID_BPF_MIN_BUFFER_SIZE)
+ return false;
+
+ switch (off) {
+ /* type, allocated_size, hdev are read-only */
+ case bpf_ctx_range_till(struct hid_bpf_ctx, type, hdev):
+ return access_type == BPF_READ;
+ }
+
+ /* everything else is read/write */
+ return true;
+}
+
+const struct bpf_verifier_ops hid_verifier_ops = {
+ .get_func_proto = hid_func_proto,
+ .is_valid_access = hid_is_valid_access
+};
+
+/* Must be called with bpf_hid_mutex held. */
+static void bpf_hid_run_array_detach(struct hid_device *hdev,
+ enum bpf_hid_attach_type type)
+{
+ struct bpf_prog_array *run_array;
+
+ run_array = rcu_replace_pointer(hdev->bpf.run_array[type], NULL,
+ lockdep_is_held(&bpf_hid_mutex));
+ bpf_prog_array_free(run_array);
+
+ if (hid_hooks.array_detached)
+ hid_hooks.array_detached(hdev, type);
+}
+
+static int link_index(struct hid_device *hdev, enum bpf_hid_attach_type type,
+ struct bpf_hid_link *link)
+{
+ struct bpf_hid_link *pos;
+ int i = 0;
+
+ list_for_each_entry(pos, &hdev->bpf.links[type], node) {
+ if (pos == link)
+ return i;
+ i++;
+ }
+ return -ENOENT;
+}
+
+static int link_count(struct hid_device *hdev, enum bpf_hid_attach_type type)
+{
+ struct list_head *pos;
+ int i = 0;
+
+ list_for_each(pos, &hdev->bpf.links[type])
+ i++;
+ return i;
+}
+
+static void fill_prog_array(struct hid_device *hdev, enum bpf_hid_attach_type type,
+ struct bpf_prog_array *prog_array)
+{
+ struct bpf_hid_link *pos;
+ unsigned int i = 0;
+
+ list_for_each_entry(pos, &hdev->bpf.links[type], node) {
+ prog_array->items[i].prog = pos->link.prog;
+ i++;
+ }
+}
+
+static void bpf_hid_link_release(struct bpf_link *link)
+{
+ struct bpf_hid_link *hid_link =
+ container_of(link, struct bpf_hid_link, link);
+ enum bpf_hid_attach_type type = hid_link->hid_type;
+ struct bpf_prog_array *old_array, *new_array;
+ struct hid_device *hdev;
+ int cnt, idx;
+
+ mutex_lock(&bpf_hid_mutex);
+
+ hdev = hid_link->hdev;
+ if (!hdev)
+ goto out_unlock;
+
+ /* Remember link position in case of safe delete */
+ idx = link_index(hdev, type, hid_link);
+ list_del(&hid_link->node);
+
+ cnt = link_count(hdev, type);
+ if (!cnt) {
+ bpf_hid_run_array_detach(hdev, type);
+ goto out_unlock;
+ }
+
+ old_array = rcu_dereference_protected(hdev->bpf.run_array[type],
+ lockdep_is_held(&bpf_hid_mutex));
+ new_array = bpf_prog_array_alloc(cnt, GFP_KERNEL);
+ if (!new_array) {
+ WARN_ON(bpf_prog_array_delete_safe_at(old_array, idx));
+ goto out_unlock;
+ }
+ fill_prog_array(hdev, type, new_array);
+ rcu_assign_pointer(hdev->bpf.run_array[type], new_array);
+ bpf_prog_array_free(old_array);
+
+out_unlock:
+ hid_link->hdev = NULL;
+ mutex_unlock(&bpf_hid_mutex);
+}
+
+static int bpf_hid_link_detach(struct bpf_link *link)
+{
+ bpf_hid_link_release(link);
+ return 0;
+}
+
+static void bpf_hid_link_dealloc(struct bpf_link *link)
+{
+ struct bpf_hid_link *hid_link =
+ container_of(link, struct bpf_hid_link, link);
+
+ kfree(hid_link);
+}
+
+static int bpf_hid_link_update_prog(struct bpf_link *link,
+ struct bpf_prog *new_prog,
+ struct bpf_prog *old_prog)
+{
+ struct bpf_hid_link *hid_link =
+ container_of(link, struct bpf_hid_link, link);
+ enum bpf_hid_attach_type type = hid_link->hid_type;
+ struct bpf_prog_array *run_array;
+ struct hid_device *hdev;
+ int idx, ret;
+
+ if (old_prog && old_prog != link->prog)
+ return -EPERM;
+ if (new_prog->type != link->prog->type)
+ return -EINVAL;
+
+ mutex_lock(&bpf_hid_mutex);
+
+ hdev = hid_link->hdev;
+ if (!hdev) {
+ /* hid dying */
+ ret = -ENOLINK;
+ goto out_unlock;
+ }
+
+ run_array = rcu_dereference_protected(hdev->bpf.run_array[type],
+ lockdep_is_held(&bpf_hid_mutex));
+ idx = link_index(hdev, type, hid_link);
+ ret = bpf_prog_array_update_at(run_array, idx, new_prog);
+ if (ret)
+ goto out_unlock;
+
+ old_prog = xchg(&link->prog, new_prog);
+ bpf_prog_put(old_prog);
+
+out_unlock:
+ mutex_unlock(&bpf_hid_mutex);
+ return ret;
+}
+
+static int bpf_hid_link_fill_info(const struct bpf_link *link,
+ struct bpf_link_info *info)
+{
+ const struct bpf_hid_link *hid_link =
+ container_of(link, struct bpf_hid_link, link);
+ int hidraw_ino = -1;
+ struct hid_device *hdev;
+ struct hidraw *hidraw;
+
+ mutex_lock(&bpf_hid_mutex);
+ hdev = hid_link->hdev;
+ if (hdev && hdev->hidraw) {
+ hidraw = hdev->hidraw;
+ hidraw_ino = hidraw->minor;
+ }
+ mutex_unlock(&bpf_hid_mutex);
+
+ info->hid.hidraw_ino = hidraw_ino;
+ info->hid.attach_type = hid_link->type;
+ return 0;
+}
+
+static void bpf_hid_link_show_fdinfo(const struct bpf_link *link,
+ struct seq_file *seq)
+{
+ struct bpf_link_info info = {};
+
+ bpf_hid_link_fill_info(link, &info);
+ seq_printf(seq,
+ "hidraw_ino:\t%u\n"
+ "attach_type:\t%u\n",
+ info.hid.hidraw_ino,
+ info.hid.attach_type);
+}
+
+static const struct bpf_link_ops bpf_hid_link_ops = {
+ .release = bpf_hid_link_release,
+ .dealloc = bpf_hid_link_dealloc,
+ .detach = bpf_hid_link_detach,
+ .update_prog = bpf_hid_link_update_prog,
+ .fill_link_info = bpf_hid_link_fill_info,
+ .show_fdinfo = bpf_hid_link_show_fdinfo,
+};
+
+/* Must be called with bpf_hid_mutex held. */
+static int __bpf_hid_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr,
+ struct hid_device *hdev,
+ enum bpf_hid_attach_type type)
+{
+ __u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
+ struct bpf_prog_array *run_array;
+ u32 prog_cnt = 0, flags = 0;
+
+ run_array = rcu_dereference_protected(hdev->bpf.run_array[type],
+ lockdep_is_held(&bpf_hid_mutex));
+ if (run_array)
+ prog_cnt = bpf_prog_array_length(run_array);
+
+ if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
+ return -EFAULT;
+ if (copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt)))
+ return -EFAULT;
+ if (!attr->query.prog_cnt || !prog_ids || !prog_cnt)
+ return 0;
+
+ return bpf_prog_array_copy_to_user(run_array, prog_ids,
+ attr->query.prog_cnt);
+}
+
+int bpf_hid_prog_query(const union bpf_attr *attr,
+ union bpf_attr __user *uattr)
+{
+ enum bpf_hid_attach_type type;
+ struct hid_device *hdev;
+ int ret;
+
+ if (attr->query.query_flags || !hid_hooks.hdev_from_fd)
+ return -EINVAL;
+
+ type = to_bpf_hid_attach_type(attr->query.attach_type);
+ if (type < 0)
+ return -EINVAL;
+
+ hdev = hid_hooks.hdev_from_fd(attr->query.target_fd);
+ if (IS_ERR(hdev))
+ return PTR_ERR(hdev);
+
+ mutex_lock(&bpf_hid_mutex);
+ ret = __bpf_hid_prog_query(attr, uattr, hdev, type);
+ mutex_unlock(&bpf_hid_mutex);
+
+ return ret;
+}
+
+static int bpf_hid_max_progs(enum bpf_hid_attach_type type)
+{
+ switch (type) {
+ case BPF_HID_ATTACH_DEVICE_EVENT:
+ return 64;
+ default:
+ return 0;
+ }
+}
+
+static int bpf_hid_link_attach(struct hid_device *hdev, struct bpf_link *link,
+ enum bpf_hid_attach_type type)
+{
+ struct bpf_hid_link *hid_link =
+ container_of(link, struct bpf_hid_link, link);
+ struct bpf_prog_array *run_array;
+ int cnt, err = 0;
+
+ mutex_lock(&bpf_hid_mutex);
+
+ cnt = link_count(hdev, type);
+ if (cnt >= bpf_hid_max_progs(type)) {
+ err = -E2BIG;
+ goto out_unlock;
+ }
+
+ if (hid_hooks.link_attach) {
+ err = hid_hooks.link_attach(hdev, type);
+ if (err)
+ goto out_unlock;
+ }
+
+ run_array = bpf_prog_array_alloc(cnt + 1, GFP_KERNEL);
+ if (!run_array) {
+ err = -ENOMEM;
+ goto out_unlock;
+ }
+
+ list_add_tail(&hid_link->node, &hdev->bpf.links[type]);
+
+ fill_prog_array(hdev, type, run_array);
+ run_array = rcu_replace_pointer(hdev->bpf.run_array[type], run_array,
+ lockdep_is_held(&bpf_hid_mutex));
+ bpf_prog_array_free(run_array);
+
+out_unlock:
+ mutex_unlock(&bpf_hid_mutex);
+ return err;
+}
+
+int bpf_hid_link_create(const union bpf_attr *attr, struct bpf_prog *prog)
+{
+ enum bpf_hid_attach_type hid_type;
+ struct bpf_link_primer link_primer;
+ struct bpf_hid_link *hid_link;
+ enum bpf_attach_type type;
+ struct hid_device *hdev;
+ int err;
+
+ if (attr->link_create.flags || !hid_hooks.hdev_from_fd)
+ return -EINVAL;
+
+ type = attr->link_create.attach_type;
+ hid_type = to_bpf_hid_attach_type(type);
+ if (hid_type < 0)
+ return -EINVAL;
+
+ hdev = hid_hooks.hdev_from_fd(attr->link_create.target_fd);
+ if (IS_ERR(hdev))
+ return PTR_ERR(hdev);
+
+ hid_link = kzalloc(sizeof(*hid_link), GFP_USER);
+ if (!hid_link)
+ return -ENOMEM;
+
+ bpf_link_init(&hid_link->link, BPF_LINK_TYPE_HID,
+ &bpf_hid_link_ops, prog);
+ hid_link->hdev = hdev;
+ hid_link->type = type;
+ hid_link->hid_type = hid_type;
+
+ err = bpf_link_prime(&hid_link->link, &link_primer);
+ if (err) {
+ kfree(hid_link);
+ return err;
+ }
+
+ err = bpf_hid_link_attach(hdev, &hid_link->link, hid_type);
+ if (err) {
+ bpf_link_cleanup(&link_primer);
+ return err;
+ }
+
+ return bpf_link_settle(&link_primer);
+}
+
+const struct bpf_prog_ops hid_prog_ops = {
+};
+
+int bpf_hid_init(struct hid_device *hdev)
+{
+ int type;
+
+ for (type = 0; type < MAX_BPF_HID_ATTACH_TYPE; type++)
+ INIT_LIST_HEAD(&hdev->bpf.links[type]);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(bpf_hid_init);
+
+void bpf_hid_exit(struct hid_device *hdev)
+{
+ enum bpf_hid_attach_type type;
+ struct bpf_hid_link *hid_link;
+
+ mutex_lock(&bpf_hid_mutex);
+ for (type = 0; type < MAX_BPF_HID_ATTACH_TYPE; type++) {
+ bpf_hid_run_array_detach(hdev, type);
+ list_for_each_entry(hid_link, &hdev->bpf.links[type], node) {
+ hid_link->hdev = NULL; /* auto-detach link */
+ }
+ }
+ mutex_unlock(&bpf_hid_mutex);
+}
+EXPORT_SYMBOL_GPL(bpf_hid_exit);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index cc570891322b..a94e78ec3211 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3,6 +3,7 @@
*/
#include <linux/bpf.h>
#include <linux/bpf-cgroup.h>
+#include <linux/bpf-hid.h>
#include <linux/bpf_trace.h>
#include <linux/bpf_lirc.h>
#include <linux/bpf_verifier.h>
@@ -2205,6 +2206,7 @@ static bool is_sys_admin_prog_type(enum bpf_prog_type prog_type)
{
switch (prog_type) {
case BPF_PROG_TYPE_LIRC_MODE2:
+ case BPF_PROG_TYPE_HID:
case BPF_PROG_TYPE_EXT: /* extends any prog */
return true;
default:
@@ -3200,6 +3202,8 @@ attach_type_to_prog_type(enum bpf_attach_type attach_type)
return BPF_PROG_TYPE_SK_LOOKUP;
case BPF_XDP:
return BPF_PROG_TYPE_XDP;
+ case BPF_HID_DEVICE_EVENT:
+ return BPF_PROG_TYPE_HID;
default:
return BPF_PROG_TYPE_UNSPEC;
}
@@ -3343,6 +3347,8 @@ static int bpf_prog_query(const union bpf_attr *attr,
case BPF_SK_MSG_VERDICT:
case BPF_SK_SKB_VERDICT:
return sock_map_bpf_prog_query(attr, uattr);
+ case BPF_HID_DEVICE_EVENT:
+ return bpf_hid_prog_query(attr, uattr);
default:
return -EINVAL;
}
@@ -4337,6 +4343,8 @@ static int link_create(union bpf_attr *attr, bpfptr_t uattr)
ret = bpf_perf_link_attach(attr, prog);
break;
#endif
+ case BPF_PROG_TYPE_HID:
+ return bpf_hid_link_create(attr, prog);
default:
ret = -EINVAL;
}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index afe3d0d7f5f2..5978b92cacd3 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -952,6 +952,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_LSM,
BPF_PROG_TYPE_SK_LOOKUP,
BPF_PROG_TYPE_SYSCALL, /* a program that can execute syscalls */
+ BPF_PROG_TYPE_HID,
};

enum bpf_attach_type {
@@ -997,6 +998,7 @@ enum bpf_attach_type {
BPF_SK_REUSEPORT_SELECT,
BPF_SK_REUSEPORT_SELECT_OR_MIGRATE,
BPF_PERF_EVENT,
+ BPF_HID_DEVICE_EVENT,
__MAX_BPF_ATTACH_TYPE
};

@@ -1011,6 +1013,7 @@ enum bpf_link_type {
BPF_LINK_TYPE_NETNS = 5,
BPF_LINK_TYPE_XDP = 6,
BPF_LINK_TYPE_PERF_EVENT = 7,
+ BPF_LINK_TYPE_HID = 8,

MAX_BPF_LINK_TYPE,
};
@@ -5870,6 +5873,10 @@ struct bpf_link_info {
struct {
__u32 ifindex;
} xdp;
+ struct {
+ __s32 hidraw_ino;
+ __u32 attach_type;
+ } hid;
};
} __attribute__((aligned(8)));

--
2.35.1