This function can not be called under IRQ, thus it is only available while in SEC("syscall"). For consistency, this function requires a HID-BPF context to work with, and so we also provide a helper to create one based on the HID unique ID.
Reviewed-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Benjamin Tissoires benjamin.tissoires@redhat.com
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changes in v9: - fixed kfunc declaration aaccording to latest upstream changes
no changes in v8
changes in v7: - hid_bpf_allocate_context: remove unused variable - ensures buf is not NULL
changes in v6: - rename parameter size into buf__sz to teach the verifier about the actual buffer size used by the call - remove the allocated data in the user created context, it's not used
new-ish in v5 --- drivers/hid/bpf/hid_bpf_dispatch.c | 132 +++++++++++++++++++++++++++++ drivers/hid/hid-core.c | 2 + include/linux/hid_bpf.h | 13 ++- 3 files changed, 146 insertions(+), 1 deletion(-)
diff --git a/drivers/hid/bpf/hid_bpf_dispatch.c b/drivers/hid/bpf/hid_bpf_dispatch.c index 33c6b3df6472..85186640e5af 100644 --- a/drivers/hid/bpf/hid_bpf_dispatch.c +++ b/drivers/hid/bpf/hid_bpf_dispatch.c @@ -220,9 +220,141 @@ hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, __u32 flags) return __hid_bpf_attach_prog(hdev, prog_type, prog_fd, flags); }
+/** + * hid_bpf_allocate_context - Allocate a context to the given HID device + * + * @hid_id: the system unique identifier of the HID device + * + * @returns A pointer to &struct hid_bpf_ctx on success, %NULL on error. + */ +noinline struct hid_bpf_ctx * +hid_bpf_allocate_context(unsigned int hid_id) +{ + struct hid_device *hdev; + struct hid_bpf_ctx_kern *ctx_kern = NULL; + struct device *dev; + + if (!hid_bpf_ops) + return NULL; + + dev = bus_find_device(hid_bpf_ops->bus_type, NULL, &hid_id, device_match_id); + if (!dev) + return NULL; + + hdev = to_hid_device(dev); + + ctx_kern = kzalloc(sizeof(*ctx_kern), GFP_KERNEL); + if (!ctx_kern) + return NULL; + + ctx_kern->ctx.hid = hdev; + + return &ctx_kern->ctx; +} + +/** + * hid_bpf_release_context - Release the previously allocated context @ctx + * + * @ctx: the HID-BPF context to release + * + */ +noinline void +hid_bpf_release_context(struct hid_bpf_ctx *ctx) +{ + struct hid_bpf_ctx_kern *ctx_kern; + + if (!ctx) + return; + + ctx_kern = container_of(ctx, struct hid_bpf_ctx_kern, ctx); + + kfree(ctx_kern); +} + +/** + * hid_bpf_hw_request - Communicate with a HID device + * + * @ctx: the HID-BPF context previously allocated in hid_bpf_allocate_context() + * @buf: a %PTR_TO_MEM buffer + * @buf__sz: the size of the data to transfer + * @rtype: the type of the report (%HID_INPUT_REPORT, %HID_FEATURE_REPORT, %HID_OUTPUT_REPORT) + * @reqtype: the type of the request (%HID_REQ_GET_REPORT, %HID_REQ_SET_REPORT, ...) + * + * @returns %0 on success, a negative error code otherwise. + */ +noinline int +hid_bpf_hw_request(struct hid_bpf_ctx *ctx, __u8 *buf, size_t buf__sz, + enum hid_report_type rtype, enum hid_class_request reqtype) +{ + struct hid_device *hdev = (struct hid_device *)ctx->hid; /* discard const */ + struct hid_report *report; + struct hid_report_enum *report_enum; + u8 *dma_data; + u32 report_len; + int ret; + + /* check arguments */ + if (!ctx || !hid_bpf_ops || !buf) + return -EINVAL; + + switch (rtype) { + case HID_INPUT_REPORT: + case HID_OUTPUT_REPORT: + case HID_FEATURE_REPORT: + break; + default: + return -EINVAL; + } + + switch (reqtype) { + case HID_REQ_GET_REPORT: + case HID_REQ_GET_IDLE: + case HID_REQ_GET_PROTOCOL: + case HID_REQ_SET_REPORT: + case HID_REQ_SET_IDLE: + case HID_REQ_SET_PROTOCOL: + break; + default: + return -EINVAL; + } + + if (buf__sz < 1) + return -EINVAL; + + report_enum = hdev->report_enum + rtype; + report = hid_bpf_ops->hid_get_report(report_enum, buf); + if (!report) + return -EINVAL; + + report_len = hid_report_len(report); + + if (buf__sz > report_len) + buf__sz = report_len; + + dma_data = kmemdup(buf, buf__sz, GFP_KERNEL); + if (!dma_data) + return -ENOMEM; + + ret = hid_bpf_ops->hid_hw_raw_request(hdev, + dma_data[0], + dma_data, + buf__sz, + rtype, + reqtype); + + if (ret > 0) + memcpy(buf, dma_data, ret); + + kfree(dma_data); + return ret; +} + /* for syscall HID-BPF */ BTF_SET8_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) BTF_SET8_END(hid_bpf_syscall_kfunc_ids)
static const struct btf_kfunc_id_set hid_bpf_syscall_kfunc_set = { diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index cadd21a6f995..9d86f6fb5a45 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -2917,6 +2917,8 @@ int hid_check_keys_pressed(struct hid_device *hid) EXPORT_SYMBOL_GPL(hid_check_keys_pressed);
static struct hid_bpf_ops hid_ops = { + .hid_get_report = hid_get_report, + .hid_hw_raw_request = hid_hw_raw_request, .owner = THIS_MODULE, .bus_type = &hid_bus_type, }; diff --git a/include/linux/hid_bpf.h b/include/linux/hid_bpf.h index 1707e4492d7a..ef76894f7705 100644 --- a/include/linux/hid_bpf.h +++ b/include/linux/hid_bpf.h @@ -61,11 +61,15 @@ struct hid_bpf_ctx { int hid_bpf_device_event(struct hid_bpf_ctx *ctx);
/* Following functions are kfunc that we export to BPF programs */ -/* only available in tracing */ +/* available everywhere in HID-BPF */ __u8 *hid_bpf_get_data(struct hid_bpf_ctx *ctx, unsigned int offset, const size_t __sz);
/* only available in syscall */ int hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, __u32 flags); +int hid_bpf_hw_request(struct hid_bpf_ctx *ctx, __u8 *buf, size_t buf__sz, + enum hid_report_type rtype, enum hid_class_request reqtype); +struct hid_bpf_ctx *hid_bpf_allocate_context(unsigned int hid_id); +void hid_bpf_release_context(struct hid_bpf_ctx *ctx);
/* * Below is HID internal @@ -84,7 +88,14 @@ enum hid_bpf_prog_type { HID_BPF_PROG_TYPE_MAX, };
+struct hid_report_enum; + struct hid_bpf_ops { + struct hid_report *(*hid_get_report)(struct hid_report_enum *report_enum, const u8 *data); + int (*hid_hw_raw_request)(struct hid_device *hdev, + unsigned char reportnum, __u8 *buf, + size_t len, enum hid_report_type rtype, + enum hid_class_request reqtype); struct module *owner; struct bus_type *bus_type; };