diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
---|---|---|
committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-11 08:27:49 +0000 |
commit | ace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch) | |
tree | b2d64bc10158fdd5497876388cd68142ca374ed3 /drivers/hid/bpf/hid_bpf_dispatch.c | |
parent | Initial commit. (diff) | |
download | linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip |
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'drivers/hid/bpf/hid_bpf_dispatch.c')
-rw-r--r-- | drivers/hid/bpf/hid_bpf_dispatch.c | 548 |
1 files changed, 548 insertions, 0 deletions
diff --git a/drivers/hid/bpf/hid_bpf_dispatch.c b/drivers/hid/bpf/hid_bpf_dispatch.c new file mode 100644 index 0000000000..d9ef45fcae --- /dev/null +++ b/drivers/hid/bpf/hid_bpf_dispatch.c @@ -0,0 +1,548 @@ +// SPDX-License-Identifier: GPL-2.0-only + +/* + * HID-BPF support for Linux + * + * Copyright (c) 2022 Benjamin Tissoires + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/bitops.h> +#include <linux/btf.h> +#include <linux/btf_ids.h> +#include <linux/filter.h> +#include <linux/hid.h> +#include <linux/hid_bpf.h> +#include <linux/init.h> +#include <linux/kfifo.h> +#include <linux/minmax.h> +#include <linux/module.h> +#include <linux/workqueue.h> +#include "hid_bpf_dispatch.h" +#include "entrypoints/entrypoints.lskel.h" + +struct hid_bpf_ops *hid_bpf_ops; +EXPORT_SYMBOL(hid_bpf_ops); + +/** + * hid_bpf_device_event - Called whenever an event is coming in from the device + * + * @ctx: The HID-BPF context + * + * @return %0 on success and keep processing; a positive value to change the + * incoming size buffer; a negative error code to interrupt the processing + * of this event + * + * Declare an %fmod_ret tracing bpf program to this function and attach this + * program through hid_bpf_attach_prog() to have this helper called for + * any incoming event from the device itself. + * + * The function is called while on IRQ context, so we can not sleep. + */ +/* never used by the kernel but declared so we can load and attach a tracepoint */ +__weak noinline int hid_bpf_device_event(struct hid_bpf_ctx *ctx) +{ + return 0; +} + +u8 * +dispatch_hid_bpf_device_event(struct hid_device *hdev, enum hid_report_type type, u8 *data, + u32 *size, int interrupt) +{ + struct hid_bpf_ctx_kern ctx_kern = { + .ctx = { + .hid = hdev, + .report_type = type, + .allocated_size = hdev->bpf.allocated_data, + .size = *size, + }, + .data = hdev->bpf.device_data, + }; + int ret; + + if (type >= HID_REPORT_TYPES) + return ERR_PTR(-EINVAL); + + /* no program has been attached yet */ + if (!hdev->bpf.device_data) + return data; + + memset(ctx_kern.data, 0, hdev->bpf.allocated_data); + memcpy(ctx_kern.data, data, *size); + + ret = hid_bpf_prog_run(hdev, HID_BPF_PROG_TYPE_DEVICE_EVENT, &ctx_kern); + if (ret < 0) + return ERR_PTR(ret); + + if (ret) { + if (ret > ctx_kern.ctx.allocated_size) + return ERR_PTR(-EINVAL); + + *size = ret; + } + + return ctx_kern.data; +} +EXPORT_SYMBOL_GPL(dispatch_hid_bpf_device_event); + +/** + * hid_bpf_rdesc_fixup - Called when the probe function parses the report + * descriptor of the HID device + * + * @ctx: The HID-BPF context + * + * @return 0 on success and keep processing; a positive value to change the + * incoming size buffer; a negative error code to interrupt the processing + * of this event + * + * Declare an %fmod_ret tracing bpf program to this function and attach this + * program through hid_bpf_attach_prog() to have this helper called before any + * parsing of the report descriptor by HID. + */ +/* never used by the kernel but declared so we can load and attach a tracepoint */ +__weak noinline int hid_bpf_rdesc_fixup(struct hid_bpf_ctx *ctx) +{ + return 0; +} + +u8 *call_hid_bpf_rdesc_fixup(struct hid_device *hdev, u8 *rdesc, unsigned int *size) +{ + int ret; + struct hid_bpf_ctx_kern ctx_kern = { + .ctx = { + .hid = hdev, + .size = *size, + .allocated_size = HID_MAX_DESCRIPTOR_SIZE, + }, + }; + + ctx_kern.data = kzalloc(ctx_kern.ctx.allocated_size, GFP_KERNEL); + if (!ctx_kern.data) + goto ignore_bpf; + + memcpy(ctx_kern.data, rdesc, min_t(unsigned int, *size, HID_MAX_DESCRIPTOR_SIZE)); + + ret = hid_bpf_prog_run(hdev, HID_BPF_PROG_TYPE_RDESC_FIXUP, &ctx_kern); + if (ret < 0) + goto ignore_bpf; + + if (ret) { + if (ret > ctx_kern.ctx.allocated_size) + goto ignore_bpf; + + *size = ret; + } + + rdesc = krealloc(ctx_kern.data, *size, GFP_KERNEL); + + return rdesc; + + ignore_bpf: + kfree(ctx_kern.data); + return kmemdup(rdesc, *size, GFP_KERNEL); +} +EXPORT_SYMBOL_GPL(call_hid_bpf_rdesc_fixup); + +/** + * hid_bpf_get_data - Get the kernel memory pointer associated with the context @ctx + * + * @ctx: The HID-BPF context + * @offset: The offset within the memory + * @rdwr_buf_size: the const size of the buffer + * + * @returns %NULL on error, an %__u8 memory pointer on success + */ +noinline __u8 * +hid_bpf_get_data(struct hid_bpf_ctx *ctx, unsigned int offset, const size_t rdwr_buf_size) +{ + struct hid_bpf_ctx_kern *ctx_kern; + + if (!ctx) + return NULL; + + ctx_kern = container_of(ctx, struct hid_bpf_ctx_kern, ctx); + + if (rdwr_buf_size + offset > ctx->allocated_size) + return NULL; + + return ctx_kern->data + offset; +} + +/* + * The following set contains all functions we agree BPF programs + * can use. + */ +BTF_SET8_START(hid_bpf_kfunc_ids) +BTF_ID_FLAGS(func, hid_bpf_get_data, KF_RET_NULL) +BTF_SET8_END(hid_bpf_kfunc_ids) + +static const struct btf_kfunc_id_set hid_bpf_kfunc_set = { + .owner = THIS_MODULE, + .set = &hid_bpf_kfunc_ids, +}; + +static int device_match_id(struct device *dev, const void *id) +{ + struct hid_device *hdev = to_hid_device(dev); + + return hdev->id == *(int *)id; +} + +static int __hid_bpf_allocate_data(struct hid_device *hdev, u8 **data, u32 *size) +{ + u8 *alloc_data; + unsigned int i, j, max_report_len = 0; + size_t alloc_size = 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; + + alloc_data = kzalloc(alloc_size, GFP_KERNEL); + if (!alloc_data) + return -ENOMEM; + + *data = alloc_data; + *size = alloc_size; + + return 0; +} + +static int hid_bpf_allocate_event_data(struct hid_device *hdev) +{ + /* hdev->bpf.device_data is already allocated, abort */ + if (hdev->bpf.device_data) + return 0; + + return __hid_bpf_allocate_data(hdev, &hdev->bpf.device_data, &hdev->bpf.allocated_data); +} + +int hid_bpf_reconnect(struct hid_device *hdev) +{ + if (!test_and_set_bit(ffs(HID_STAT_REPROBED), &hdev->status)) + return device_reprobe(&hdev->dev); + + return 0; +} + +/** + * hid_bpf_attach_prog - Attach the given @prog_fd to the given HID device + * + * @hid_id: the system unique identifier of the HID device + * @prog_fd: an fd in the user process representing the program to attach + * @flags: any logical OR combination of &enum hid_bpf_attach_flags + * + * @returns an fd of a bpf_link object on success (> %0), an error code otherwise. + * Closing this fd will detach the program from the HID device (unless the bpf_link + * is pinned to the BPF file system). + */ +/* called from syscall */ +noinline int +hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, __u32 flags) +{ + struct hid_device *hdev; + struct device *dev; + int fd, err, prog_type = hid_bpf_get_prog_attach_type(prog_fd); + + if (!hid_bpf_ops) + return -EINVAL; + + if (prog_type < 0) + return prog_type; + + if (prog_type >= HID_BPF_PROG_TYPE_MAX) + return -EINVAL; + + if ((flags & ~HID_BPF_FLAG_MASK)) + return -EINVAL; + + dev = bus_find_device(hid_bpf_ops->bus_type, NULL, &hid_id, device_match_id); + if (!dev) + return -EINVAL; + + hdev = to_hid_device(dev); + + if (prog_type == HID_BPF_PROG_TYPE_DEVICE_EVENT) { + err = hid_bpf_allocate_event_data(hdev); + if (err) + return err; + } + + fd = __hid_bpf_attach_prog(hdev, prog_type, prog_fd, flags); + if (fd < 0) + return fd; + + if (prog_type == HID_BPF_PROG_TYPE_RDESC_FIXUP) { + err = hid_bpf_reconnect(hdev); + if (err) { + close_fd(fd); + return err; + } + } + + return fd; +} + +/** + * 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; + + 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_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; + + hdev = (struct hid_device *)ctx->hid; /* discard const */ + + 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; +} + +/* our HID-BPF entrypoints */ +BTF_SET8_START(hid_bpf_fmodret_ids) +BTF_ID_FLAGS(func, hid_bpf_device_event) +BTF_ID_FLAGS(func, hid_bpf_rdesc_fixup) +BTF_ID_FLAGS(func, __hid_bpf_tail_call) +BTF_SET8_END(hid_bpf_fmodret_ids) + +static const struct btf_kfunc_id_set hid_bpf_fmodret_set = { + .owner = THIS_MODULE, + .set = &hid_bpf_fmodret_ids, +}; + +/* 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 = { + .owner = THIS_MODULE, + .set = &hid_bpf_syscall_kfunc_ids, +}; + +int hid_bpf_connect_device(struct hid_device *hdev) +{ + struct hid_bpf_prog_list *prog_list; + + rcu_read_lock(); + prog_list = rcu_dereference(hdev->bpf.progs[HID_BPF_PROG_TYPE_DEVICE_EVENT]); + rcu_read_unlock(); + + /* only allocate BPF data if there are programs attached */ + if (!prog_list) + return 0; + + return hid_bpf_allocate_event_data(hdev); +} +EXPORT_SYMBOL_GPL(hid_bpf_connect_device); + +void hid_bpf_disconnect_device(struct hid_device *hdev) +{ + kfree(hdev->bpf.device_data); + hdev->bpf.device_data = NULL; + hdev->bpf.allocated_data = 0; +} +EXPORT_SYMBOL_GPL(hid_bpf_disconnect_device); + +void hid_bpf_destroy_device(struct hid_device *hdev) +{ + if (!hdev) + return; + + /* mark the device as destroyed in bpf so we don't reattach it */ + hdev->bpf.destroyed = true; + + __hid_bpf_destroy_device(hdev); +} +EXPORT_SYMBOL_GPL(hid_bpf_destroy_device); + +void hid_bpf_device_init(struct hid_device *hdev) +{ + spin_lock_init(&hdev->bpf.progs_lock); +} +EXPORT_SYMBOL_GPL(hid_bpf_device_init); + +static int __init hid_bpf_init(void) +{ + int err; + + /* Note: if we exit with an error any time here, we would entirely break HID, which + * is probably not something we want. So we log an error and return success. + * + * This is not a big deal: the syscall allowing to attach a BPF program to a HID device + * will not be available, so nobody will be able to use the functionality. + */ + + err = register_btf_fmodret_id_set(&hid_bpf_fmodret_set); + if (err) { + pr_warn("error while registering fmodret entrypoints: %d", err); + return 0; + } + + err = hid_bpf_preload_skel(); + if (err) { + pr_warn("error while preloading HID BPF dispatcher: %d", err); + return 0; + } + + /* register tracing kfuncs after we are sure we can load our preloaded bpf program */ + err = register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &hid_bpf_kfunc_set); + if (err) { + pr_warn("error while setting HID BPF tracing kfuncs: %d", err); + return 0; + } + + /* register syscalls after we are sure we can load our preloaded bpf program */ + err = register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &hid_bpf_syscall_kfunc_set); + if (err) { + pr_warn("error while setting HID BPF syscall kfuncs: %d", err); + return 0; + } + + return 0; +} + +static void __exit hid_bpf_exit(void) +{ + /* HID depends on us, so if we hit that code, we are guaranteed that hid + * has been removed and thus we do not need to clear the HID devices + */ + hid_bpf_free_links_and_skel(); +} + +late_initcall(hid_bpf_init); +module_exit(hid_bpf_exit); +MODULE_AUTHOR("Benjamin Tissoires"); +MODULE_LICENSE("GPL"); |