diff options
author | Benjamin Tissoires <benjamin.tissoires@redhat.com> | 2022-11-03 16:57:51 +0100 |
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committer | Jiri Kosina <jkosina@suse.cz> | 2022-11-15 16:28:39 +0100 |
commit | ad190df11a024c1214fbc8dcaab72c592c79d9b5 (patch) | |
tree | 3ff7fc64a04187c78f64a37408001b93186de03a /drivers/hid | |
parent | 4f7153cf461ed0f78d8da8c9fd02d38728a76b90 (diff) | |
download | linux-stable-ad190df11a024c1214fbc8dcaab72c592c79d9b5.tar.gz linux-stable-ad190df11a024c1214fbc8dcaab72c592c79d9b5.tar.bz2 linux-stable-ad190df11a024c1214fbc8dcaab72c592c79d9b5.zip |
HID: bpf: allow to change the report descriptor
Add a new tracepoint hid_bpf_rdesc_fixup() so we can trigger a
report descriptor fixup in the bpf world.
Whenever the program gets attached/detached, the device is reconnected
meaning that userspace will see it disappearing and reappearing with
the new report descriptor.
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Diffstat (limited to 'drivers/hid')
-rw-r--r-- | drivers/hid/bpf/hid_bpf_dispatch.c | 80 | ||||
-rw-r--r-- | drivers/hid/bpf/hid_bpf_dispatch.h | 1 | ||||
-rw-r--r-- | drivers/hid/bpf/hid_bpf_jmp_table.c | 7 | ||||
-rw-r--r-- | drivers/hid/hid-core.c | 3 |
4 files changed, 89 insertions, 2 deletions
diff --git a/drivers/hid/bpf/hid_bpf_dispatch.c b/drivers/hid/bpf/hid_bpf_dispatch.c index 0fe856d67f12..c3920c7964dc 100644 --- a/drivers/hid/bpf/hid_bpf_dispatch.c +++ b/drivers/hid/bpf/hid_bpf_dispatch.c @@ -15,6 +15,7 @@ #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" @@ -86,6 +87,65 @@ dispatch_hid_bpf_device_event(struct hid_device *hdev, enum hid_report_type type 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; +} +ALLOW_ERROR_INJECTION(hid_bpf_rdesc_fixup, ERRNO); + +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 @@ -176,6 +236,14 @@ static int hid_bpf_allocate_event_data(struct hid_device *hdev) 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 * @@ -217,7 +285,17 @@ hid_bpf_attach_prog(unsigned int hid_id, int prog_fd, __u32 flags) return err; } - return __hid_bpf_attach_prog(hdev, prog_type, prog_fd, flags); + err = __hid_bpf_attach_prog(hdev, prog_type, prog_fd, flags); + if (err) + return err; + + if (prog_type == HID_BPF_PROG_TYPE_RDESC_FIXUP) { + err = hid_bpf_reconnect(hdev); + if (err) + return err; + } + + return 0; } /** diff --git a/drivers/hid/bpf/hid_bpf_dispatch.h b/drivers/hid/bpf/hid_bpf_dispatch.h index e2d64faa3932..2eeab1f746dd 100644 --- a/drivers/hid/bpf/hid_bpf_dispatch.h +++ b/drivers/hid/bpf/hid_bpf_dispatch.h @@ -18,6 +18,7 @@ int __hid_bpf_attach_prog(struct hid_device *hdev, enum hid_bpf_prog_type prog_t void __hid_bpf_destroy_device(struct hid_device *hdev); int hid_bpf_prog_run(struct hid_device *hdev, enum hid_bpf_prog_type type, struct hid_bpf_ctx_kern *ctx_kern); +int hid_bpf_reconnect(struct hid_device *hdev); struct bpf_prog; diff --git a/drivers/hid/bpf/hid_bpf_jmp_table.c b/drivers/hid/bpf/hid_bpf_jmp_table.c index bfcdd7b805a9..579a6c06906e 100644 --- a/drivers/hid/bpf/hid_bpf_jmp_table.c +++ b/drivers/hid/bpf/hid_bpf_jmp_table.c @@ -58,12 +58,15 @@ static DECLARE_WORK(release_work, hid_bpf_release_progs); BTF_ID_LIST(hid_bpf_btf_ids) BTF_ID(func, hid_bpf_device_event) /* HID_BPF_PROG_TYPE_DEVICE_EVENT */ +BTF_ID(func, hid_bpf_rdesc_fixup) /* HID_BPF_PROG_TYPE_RDESC_FIXUP */ static int hid_bpf_max_programs(enum hid_bpf_prog_type type) { switch (type) { case HID_BPF_PROG_TYPE_DEVICE_EVENT: return HID_BPF_MAX_PROGS_PER_DEV; + case HID_BPF_PROG_TYPE_RDESC_FIXUP: + return 1; default: return -EINVAL; } @@ -233,6 +236,10 @@ static void hid_bpf_release_progs(struct work_struct *work) if (next->hdev == hdev && next->type == type) next->hdev = NULL; } + + /* if type was rdesc fixup, reconnect device */ + if (type == HID_BPF_PROG_TYPE_RDESC_FIXUP) + hid_bpf_reconnect(hdev); } } diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index 6bf47e352f23..fa4436b8101e 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1218,7 +1218,8 @@ int hid_open_report(struct hid_device *device) return -ENODEV; size = device->dev_rsize; - buf = kmemdup(start, size, GFP_KERNEL); + /* call_hid_bpf_rdesc_fixup() ensures we work on a copy of rdesc */ + buf = call_hid_bpf_rdesc_fixup(device, start, &size); if (buf == NULL) return -ENOMEM; |