git/linux-cryptodev-2.6
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git synced 2026-04-18 03:23:53 -04:00
Code Issues Packages Projects Releases Wiki Activity

HID: bpf: prevent infinite recursions with hid_hw_raw_requests hooks

Browse Source 
When we attach a sleepable hook to hid_hw_raw_requests, we can (and in
many cases should) call ourself hid_bpf_raw_request(), to actually fetch
data from the device itself.

However, this means that we might enter an infinite loop between
hid_hw_raw_requests hooks and hid_bpf_hw_request() call.

To prevent that, if a hid_bpf_hw_request() call is emitted, we prevent
any new call of this kfunc by storing the information in the context.
This way we can always trace/monitor/filter the incoming bpf requests,
while preventing those loops to happen.

I don't think exposing "from_bpf" is very interesting because while
writing such a bpf program, you need to match at least the report number
and/or the source of the call. So a blind "if there is a
hid_hw_raw_request() call, I'm emitting another one" makes no real
sense.

Link: https://patch.msgid.link/20240626-hid_hw_req_bpf-v2-5-cfd60fb6c79f@kernel.org
Acked-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
This commit is contained in:
Benjamin Tissoires
2024-06-26 15:46:26 +02:00
parent 8bd0488b5e
commit 75839101ce
6 changed files with 20 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/hid_bpf.h
View File

@@ -68,7 +68,7 @@ struct hid_ops {
unsigned char reportnum, __u8 *buf,
size_t len, enum hid_report_type rtype,
enum hid_class_request reqtype,
__u64 source);
__u64 source, bool from_bpf);
int (*hid_hw_output_report)(struct hid_device *hdev, __u8 *buf, size_t len,
__u64 source);
int (*hid_input_report)(struct hid_device *hid, enum hid_report_type type,
@@ -181,7 +181,7 @@ int dispatch_hid_bpf_raw_requests(struct hid_device *hdev,
unsigned char reportnum, __u8 *buf,
u32 size, enum hid_report_type rtype,
enum hid_class_request reqtype,
__u64 source);
__u64 source, bool from_bpf);
int hid_bpf_connect_device(struct hid_device *hdev);
void hid_bpf_disconnect_device(struct hid_device *hdev);
void hid_bpf_destroy_device(struct hid_device *hid);
@@ -195,7 +195,7 @@ static inline int dispatch_hid_bpf_raw_requests(struct hid_device *hdev,
unsigned char reportnum, u8 *buf,
u32 size, enum hid_report_type rtype,
enum hid_class_request reqtype,
u64 source) { return 0; }
u64 source, bool from_bpf) { return 0; }
static inline int hid_bpf_connect_device(struct hid_device *hdev) { return 0; }
static inline void hid_bpf_disconnect_device(struct hid_device *hdev) {}
static inline void hid_bpf_destroy_device(struct hid_device *hid) {}