| Message ID | 20220318161528.1531164-6-benjamin.tissoires@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | Introduce eBPF support for HID devices | expand |
On Fri, Mar 18, 2022 at 9:17 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. So we only need this part for DEVICE EVENT? > > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> > > --- > > changes in v3: > - squashed "only call hid_bpf_raw_event() if a ctx is available" > and "bpf: compute only the required buffer size for the device" > into this one > - ensure the ctx.size is properly bounded by allocated size > - s/link_attach/pre_link_attach/ > - s/array_detached/array_detach/ > - fix default switch case when doing nothing > - reworked hid_bpf_pre_link_attach() to avoid the switch > > 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 | 174 +++++++++++++++++++++++++++++++++++++++++ > drivers/hid/hid-core.c | 24 +++++- > include/linux/hid.h | 11 +++ > 4 files changed, 207 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..5060ebcb9979 > --- /dev/null > +++ b/drivers/hid/hid-bpf.c > @@ -0,0 +1,174 @@ > +// 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_pre_link_attach(struct hid_device *hdev, enum bpf_hid_attach_type type) > +{ > + int err = 0; > + unsigned int i, j, max_report_len = 0; > + unsigned int alloc_size = 0; > + > + if (type != BPF_HID_ATTACH_DEVICE_EVENT) > + return 0; > + > + /* hdev->bpf.device_data is already allocated, abort */ > + if (hdev->bpf.device_data) > + return 0; > + > + /* compute the maximum report length for this device */ > + for (i = 0; i < HID_REPORT_TYPES; i++) { > + struct hid_report_enum *report_enum = hdev->report_enum + i; > + > + for (j = 0; j < HID_MAX_IDS; j++) { > + struct hid_report *report = report_enum->report_id_hash[j]; > + > + if (report) > + max_report_len = max(max_report_len, hid_report_len(report)); > + } > + } > + > + /* > + * Give us a little bit of extra space and some predictability in the > + * buffer length we create. This way, we can tell users that they can > + * work on chunks of 64 bytes of memory without having the bpf verifier > + * scream at them. > + */ > + alloc_size = DIV_ROUND_UP(max_report_len, 64) * 64; > + > + hdev->bpf.device_data = kzalloc(alloc_size, GFP_KERNEL); > + if (!hdev->bpf.device_data) > + err = -ENOMEM; > + else > + hdev->bpf.allocated_data = alloc_size; > + > + return err; > +} > + > +static void hid_bpf_array_detach(struct hid_device *hdev, enum bpf_hid_attach_type type) > +{ > + switch (type) { > + case BPF_HID_ATTACH_DEVICE_EVENT: > + kfree(hdev->bpf.device_data); > + hdev->bpf.device_data = NULL; > + break; > + default: > + /* do nothing */ > + break; > + } > +} > + > +static int hid_bpf_run_progs(struct hid_device *hdev, struct hid_bpf_ctx_kern *ctx) > +{ > + enum bpf_hid_attach_type type; > + > + if (!ctx) > + return -EINVAL; > + > + switch (ctx->type) { > + case HID_BPF_DEVICE_EVENT: > + type = BPF_HID_ATTACH_DEVICE_EVENT; > + break; > + default: > + return -EINVAL; > + } > + > + if (!hdev->bpf.run_array[type]) > + return 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; > + struct hid_bpf_ctx_kern ctx = { > + .type = HID_BPF_DEVICE_EVENT, > + .hdev = hdev, > + .size = *size, > + .data = hdev->bpf.device_data, > + .allocated_size = hdev->bpf.allocated_data, > + }; > + > + if (bpf_hid_link_empty(&hdev->bpf, BPF_HID_ATTACH_DEVICE_EVENT)) > + return data; > + > + memset(ctx.data, 0, hdev->bpf.allocated_data); > + memcpy(ctx.data, data, *size); > + > + ret = hid_bpf_run_progs(hdev, &ctx); > + if (ret) > + return ERR_PTR(-EIO); > + > + if (!ctx.size || ctx.size > ctx.allocated_size) > + return ERR_PTR(-EINVAL); > + > + *size = ctx.size; > + > + return ctx.data; > +} > + > +int __init hid_bpf_module_init(void) > +{ > + struct bpf_hid_hooks hooks = { > + .hdev_from_fd = hid_bpf_fd_to_hdev, > + .pre_link_attach = hid_bpf_pre_link_attach, > + .array_detach = hid_bpf_array_detach, > + }; > + > + 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..937fab7eb9c6 100644 > --- a/drivers/hid/hid-core.c > +++ b/drivers/hid/hid-core.c > @@ -1748,13 +1748,24 @@ 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; > > + /* we pre-test if device_data is available here to cut the calls at the earliest */ > + if (hid->bpf.device_data) { > + 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 +2539,12 @@ 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 +2580,7 @@ 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 +2588,7 @@ 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 +2715,8 @@ static int __init hid_init(void) > > hid_debug_init(); > > + hid_bpf_module_init(); > + > return 0; > err_bus: > bus_unregister(&hid_bus_type); > @@ -2709,6 +2726,7 @@ 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 > -- > 2.35.1 >
On Fri, Mar 18, 2022 at 2:02 PM Song Liu <song@kernel.org> wrote: > > On Fri, Mar 18, 2022 at 9:17 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. > > So we only need this part for DEVICE EVENT? NVM, I found other types in the following patches. > > > > > Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> > > > > --- > > > > changes in v3: > > - squashed "only call hid_bpf_raw_event() if a ctx is available" > > and "bpf: compute only the required buffer size for the device" > > into this one > > - ensure the ctx.size is properly bounded by allocated size > > - s/link_attach/pre_link_attach/ > > - s/array_detached/array_detach/ > > - fix default switch case when doing nothing > > - reworked hid_bpf_pre_link_attach() to avoid the switch > > > > 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 | 174 +++++++++++++++++++++++++++++++++++++++++ > > drivers/hid/hid-core.c | 24 +++++- > > include/linux/hid.h | 11 +++ > > 4 files changed, 207 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..5060ebcb9979 > > --- /dev/null > > +++ b/drivers/hid/hid-bpf.c > > @@ -0,0 +1,174 @@ > > +// 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_pre_link_attach(struct hid_device *hdev, enum bpf_hid_attach_type type) > > +{ > > + int err = 0; > > + unsigned int i, j, max_report_len = 0; > > + unsigned int alloc_size = 0; > > + > > + if (type != BPF_HID_ATTACH_DEVICE_EVENT) > > + return 0; > > + > > + /* hdev->bpf.device_data is already allocated, abort */ > > + if (hdev->bpf.device_data) > > + return 0; > > + > > + /* compute the maximum report length for this device */ > > + for (i = 0; i < HID_REPORT_TYPES; i++) { > > + struct hid_report_enum *report_enum = hdev->report_enum + i; > > + > > + for (j = 0; j < HID_MAX_IDS; j++) { > > + struct hid_report *report = report_enum->report_id_hash[j]; > > + > > + if (report) > > + max_report_len = max(max_report_len, hid_report_len(report)); > > + } > > + } > > + > > + /* > > + * Give us a little bit of extra space and some predictability in the > > + * buffer length we create. This way, we can tell users that they can > > + * work on chunks of 64 bytes of memory without having the bpf verifier > > + * scream at them. > > + */ > > + alloc_size = DIV_ROUND_UP(max_report_len, 64) * 64; > > + > > + hdev->bpf.device_data = kzalloc(alloc_size, GFP_KERNEL); > > + if (!hdev->bpf.device_data) > > + err = -ENOMEM; > > + else > > + hdev->bpf.allocated_data = alloc_size; > > + > > + return err; > > +} > > + > > +static void hid_bpf_array_detach(struct hid_device *hdev, enum bpf_hid_attach_type type) > > +{ > > + switch (type) { > > + case BPF_HID_ATTACH_DEVICE_EVENT: > > + kfree(hdev->bpf.device_data); > > + hdev->bpf.device_data = NULL; > > + break; > > + default: > > + /* do nothing */ > > + break; > > + } > > +} > > + > > +static int hid_bpf_run_progs(struct hid_device *hdev, struct hid_bpf_ctx_kern *ctx) > > +{ > > + enum bpf_hid_attach_type type; > > + > > + if (!ctx) > > + return -EINVAL; > > + > > + switch (ctx->type) { > > + case HID_BPF_DEVICE_EVENT: > > + type = BPF_HID_ATTACH_DEVICE_EVENT; > > + break; > > + default: > > + return -EINVAL; > > + } > > + > > + if (!hdev->bpf.run_array[type]) > > + return 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; > > + struct hid_bpf_ctx_kern ctx = { > > + .type = HID_BPF_DEVICE_EVENT, > > + .hdev = hdev, > > + .size = *size, > > + .data = hdev->bpf.device_data, > > + .allocated_size = hdev->bpf.allocated_data, > > + }; > > + > > + if (bpf_hid_link_empty(&hdev->bpf, BPF_HID_ATTACH_DEVICE_EVENT)) > > + return data; > > + > > + memset(ctx.data, 0, hdev->bpf.allocated_data); > > + memcpy(ctx.data, data, *size); > > + > > + ret = hid_bpf_run_progs(hdev, &ctx); > > + if (ret) > > + return ERR_PTR(-EIO); > > + > > + if (!ctx.size || ctx.size > ctx.allocated_size) > > + return ERR_PTR(-EINVAL); > > + > > + *size = ctx.size; > > + > > + return ctx.data; > > +} > > + > > +int __init hid_bpf_module_init(void) > > +{ > > + struct bpf_hid_hooks hooks = { > > + .hdev_from_fd = hid_bpf_fd_to_hdev, > > + .pre_link_attach = hid_bpf_pre_link_attach, > > + .array_detach = hid_bpf_array_detach, > > + }; > > + > > + 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..937fab7eb9c6 100644 > > --- a/drivers/hid/hid-core.c > > +++ b/drivers/hid/hid-core.c > > @@ -1748,13 +1748,24 @@ 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; > > > > + /* we pre-test if device_data is available here to cut the calls at the earliest */ > > + if (hid->bpf.device_data) { > > + 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 +2539,12 @@ 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 +2580,7 @@ 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 +2588,7 @@ 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 +2715,8 @@ static int __init hid_init(void) > > > > hid_debug_init(); > > > > + hid_bpf_module_init(); > > + > > return 0; > > err_bus: > > bus_unregister(&hid_bus_type); > > @@ -2709,6 +2726,7 @@ 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 > > -- > > 2.35.1 > >
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..5060ebcb9979 --- /dev/null +++ b/drivers/hid/hid-bpf.c @@ -0,0 +1,174 @@ +// 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_pre_link_attach(struct hid_device *hdev, enum bpf_hid_attach_type type) +{ + int err = 0; + unsigned int i, j, max_report_len = 0; + unsigned int alloc_size = 0; + + if (type != BPF_HID_ATTACH_DEVICE_EVENT) + return 0; + + /* hdev->bpf.device_data is already allocated, abort */ + if (hdev->bpf.device_data) + return 0; + + /* compute the maximum report length for this device */ + for (i = 0; i < HID_REPORT_TYPES; i++) { + struct hid_report_enum *report_enum = hdev->report_enum + i; + + for (j = 0; j < HID_MAX_IDS; j++) { + struct hid_report *report = report_enum->report_id_hash[j]; + + if (report) + max_report_len = max(max_report_len, hid_report_len(report)); + } + } + + /* + * Give us a little bit of extra space and some predictability in the + * buffer length we create. This way, we can tell users that they can + * work on chunks of 64 bytes of memory without having the bpf verifier + * scream at them. + */ + alloc_size = DIV_ROUND_UP(max_report_len, 64) * 64; + + hdev->bpf.device_data = kzalloc(alloc_size, GFP_KERNEL); + if (!hdev->bpf.device_data) + err = -ENOMEM; + else + hdev->bpf.allocated_data = alloc_size; + + return err; +} + +static void hid_bpf_array_detach(struct hid_device *hdev, enum bpf_hid_attach_type type) +{ + switch (type) { + case BPF_HID_ATTACH_DEVICE_EVENT: + kfree(hdev->bpf.device_data); + hdev->bpf.device_data = NULL; + break; + default: + /* do nothing */ + break; + } +} + +static int hid_bpf_run_progs(struct hid_device *hdev, struct hid_bpf_ctx_kern *ctx) +{ + enum bpf_hid_attach_type type; + + if (!ctx) + return -EINVAL; + + switch (ctx->type) { + case HID_BPF_DEVICE_EVENT: + type = BPF_HID_ATTACH_DEVICE_EVENT; + break; + default: + return -EINVAL; + } + + if (!hdev->bpf.run_array[type]) + return 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; + struct hid_bpf_ctx_kern ctx = { + .type = HID_BPF_DEVICE_EVENT, + .hdev = hdev, + .size = *size, + .data = hdev->bpf.device_data, + .allocated_size = hdev->bpf.allocated_data, + }; + + if (bpf_hid_link_empty(&hdev->bpf, BPF_HID_ATTACH_DEVICE_EVENT)) + return data; + + memset(ctx.data, 0, hdev->bpf.allocated_data); + memcpy(ctx.data, data, *size); + + ret = hid_bpf_run_progs(hdev, &ctx); + if (ret) + return ERR_PTR(-EIO); + + if (!ctx.size || ctx.size > ctx.allocated_size) + return ERR_PTR(-EINVAL); + + *size = ctx.size; + + return ctx.data; +} + +int __init hid_bpf_module_init(void) +{ + struct bpf_hid_hooks hooks = { + .hdev_from_fd = hid_bpf_fd_to_hdev, + .pre_link_attach = hid_bpf_pre_link_attach, + .array_detach = hid_bpf_array_detach, + }; + + 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..937fab7eb9c6 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1748,13 +1748,24 @@ 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; + /* we pre-test if device_data is available here to cut the calls at the earliest */ + if (hid->bpf.device_data) { + 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 +2539,12 @@ 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 +2580,7 @@ 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 +2588,7 @@ 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 +2715,8 @@ static int __init hid_init(void) hid_debug_init(); + hid_bpf_module_init(); + return 0; err_bus: bus_unregister(&hid_bus_type); @@ -2709,6 +2726,7 @@ 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
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 v3: - squashed "only call hid_bpf_raw_event() if a ctx is available" and "bpf: compute only the required buffer size for the device" into this one - ensure the ctx.size is properly bounded by allocated size - s/link_attach/pre_link_attach/ - s/array_detached/array_detach/ - fix default switch case when doing nothing - reworked hid_bpf_pre_link_attach() to avoid the switch 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 | 174 +++++++++++++++++++++++++++++++++++++++++ drivers/hid/hid-core.c | 24 +++++- include/linux/hid.h | 11 +++ 4 files changed, 207 insertions(+), 3 deletions(-) create mode 100644 drivers/hid/hid-bpf.c