diff mbox series

[bpf-next,v2,03/28] HID: hook up with bpf

Message ID 20220304172852.274126-4-benjamin.tissoires@redhat.com (mailing list archive)
State Superseded
Headers show
Series Introduce eBPF support for HID devices | expand

Commit Message

Benjamin Tissoires March 4, 2022, 5:28 p.m. UTC 
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@redhat.com>

---

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

Comments

Greg KH March 4, 2022, 6:24 p.m. UTC | #1 
On Fri, Mar 04, 2022 at 06:28:27PM +0100, 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@redhat.com>
> 

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Song Liu March 5, 2022, 12:23 a.m. UTC | #2 
On Fri, Mar 4, 2022 at 9:31 AM Benjamin Tissoires
<benjamin.tissoires@redhat.com> 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@redhat.com>
>
[...]

> +
> +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 */

Do we need to show warning and/or return EINVAL here?

> +       }
> +
> +       return err;
> +}
> +
> +static void hid_bpf_array_detached(struct hid_device *hdev, enum bpf_hid_attach_type type)
> +{
> +       switch (type) {
> +       case BPF_HID_ATTACH_DEVICE_EVENT:
> +               kfree(hdev->bpf.ctx);
> +               hdev->bpf.ctx = NULL;
> +               break;
> +       default:
> +               /* do nothing */

ditto

[...]
Tero Kristo March 15, 2022, 4:29 p.m. UTC | #3 
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@redhat.com>
>
> ---
>
> 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
diff mbox series

Patch

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 */
+	}
+
+	return err;
+}
+
+static void hid_bpf_array_detached(struct hid_device *hdev, enum bpf_hid_attach_type type)
+{
+	switch (type) {
+	case BPF_HID_ATTACH_DEVICE_EVENT:
+		kfree(hdev->bpf.ctx);
+		hdev->bpf.ctx = NULL;
+		break;
+	default:
+		/* do nothing */
+	}
+}
+
+static int hid_bpf_run_progs(struct hid_device *hdev, enum bpf_hid_attach_type type,
+			     struct hid_bpf_ctx *ctx, u8 *data, int size)
+{
+	enum hid_bpf_event event = HID_BPF_UNDEF;
+
+	if (type < 0 || !ctx)
+		return -EINVAL;
+
+	if (size > ctx->allocated_size)
+		return -E2BIG;
+
+	switch (type) {
+	case BPF_HID_ATTACH_DEVICE_EVENT:
+		event = HID_BPF_DEVICE_EVENT;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (!hdev->bpf.run_array[type])
+		return 0;
+
+	memset(ctx->data, 0, ctx->allocated_size);
+	ctx->type = event;
+
+	if (size && data) {
+		memcpy(ctx->data, data, size);
+		ctx->size = size;
+	} else {
+		ctx->size = 0;
+	}
+
+	return BPF_PROG_RUN_ARRAY(hdev->bpf.run_array[type], ctx, bpf_prog_run);
+}
+
+u8 *hid_bpf_raw_event(struct hid_device *hdev, u8 *data, int *size)
+{
+	int ret;
+
+	if (bpf_hid_link_empty(&hdev->bpf, BPF_HID_ATTACH_DEVICE_EVENT))
+		return data;
+
+	ret = hid_bpf_run_progs(hdev, BPF_HID_ATTACH_DEVICE_EVENT,
+				hdev->bpf.ctx, data, *size);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (!hdev->bpf.ctx->size)
+		return ERR_PTR(-EINVAL);
+
+	*size = hdev->bpf.ctx->size;
+
+	return hdev->bpf.ctx->data;
+}
+
+int __init hid_bpf_module_init(void)
+{
+	struct bpf_hid_hooks hooks = {
+		.hdev_from_fd = hid_bpf_fd_to_hdev,
+		.link_attach = hid_bpf_link_attach,
+		.array_detached = hid_bpf_array_detached,
+	};
+
+	bpf_hid_set_hooks(&hooks);
+
+	return 0;
+}
+
+void __exit hid_bpf_module_exit(void)
+{
+	bpf_hid_set_hooks(NULL);
+}
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index f1aed5bbd000..a80bffe6ce4a 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1748,13 +1748,21 @@  int hid_report_raw_event(struct hid_device *hid, int type, u8 *data, u32 size,
 	struct hid_driver *hdrv;
 	unsigned int a;
 	u32 rsize, csize = size;
-	u8 *cdata = data;
+	u8 *cdata;
 	int ret = 0;
 
+	data = hid_bpf_raw_event(hid, data, &size);
+	if (IS_ERR(data)) {
+		ret = PTR_ERR(data);
+		goto out;
+	}
+
 	report = hid_get_report(report_enum, data);
 	if (!report)
 		goto out;
 
+	cdata = data;
+
 	if (report_enum->numbered) {
 		cdata++;
 		csize--;
@@ -2528,10 +2536,12 @@  int hid_add_device(struct hid_device *hdev)
 
 	hid_debug_register(hdev, dev_name(&hdev->dev));
 	ret = device_add(&hdev->dev);
-	if (!ret)
+	if (!ret) {
 		hdev->status |= HID_STAT_ADDED;
-	else
+	} else {
 		hid_debug_unregister(hdev);
+		bpf_hid_exit(hdev);
+	}
 
 	return ret;
 }
@@ -2567,6 +2577,7 @@  struct hid_device *hid_allocate_device(void)
 	spin_lock_init(&hdev->debug_list_lock);
 	sema_init(&hdev->driver_input_lock, 1);
 	mutex_init(&hdev->ll_open_lock);
+	bpf_hid_init(hdev);
 
 	return hdev;
 }
@@ -2574,6 +2585,7 @@  EXPORT_SYMBOL_GPL(hid_allocate_device);
 
 static void hid_remove_device(struct hid_device *hdev)
 {
+	bpf_hid_exit(hdev);
 	if (hdev->status & HID_STAT_ADDED) {
 		device_del(&hdev->dev);
 		hid_debug_unregister(hdev);
@@ -2700,6 +2712,8 @@  static int __init hid_init(void)
 
 	hid_debug_init();
 
+	hid_bpf_module_init();
+
 	return 0;
 err_bus:
 	bus_unregister(&hid_bus_type);
@@ -2709,6 +2723,7 @@  static int __init hid_init(void)
 
 static void __exit hid_exit(void)
 {
+	hid_bpf_module_exit();
 	hid_debug_exit();
 	hidraw_exit();
 	bus_unregister(&hid_bus_type);
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 56f6f4ad45a7..8fd79011f461 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -27,6 +27,7 @@ 
 #include <linux/mutex.h>
 #include <linux/power_supply.h>
 #include <uapi/linux/hid.h>
+#include <uapi/linux/bpf_hid.h>
 
 /*
  * We parse each description item into this structure. Short items data
@@ -1210,4 +1211,14 @@  do {									\
 #define hid_dbg_once(hid, fmt, ...)			\
 	dev_dbg_once(&(hid)->dev, fmt, ##__VA_ARGS__)
 
+#ifdef CONFIG_BPF
+u8 *hid_bpf_raw_event(struct hid_device *hdev, u8 *rd, int *size);
+int hid_bpf_module_init(void);
+void hid_bpf_module_exit(void);
+#else
+static inline u8 *hid_bpf_raw_event(struct hid_device *hdev, u8 *rd, int *size) { return rd; }
+static inline int hid_bpf_module_init(void) { return 0; }
+static inline void hid_bpf_module_exit(void) {}
+#endif
+
 #endif