HID: provide a helper for validating hid reports
Many drivers need to validate the characteristics of their HID report during initialization to avoid misusing the reports. This adds a common helper to perform validation of the report exisitng, the field existing, and the expected number of values within the field. Signed-off-by: Kees Cook <keescook@chromium.org> Cc: stable@vger.kernel.org Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
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@@ -801,6 +801,64 @@ int hid_parse_report(struct hid_device *hid, __u8 *start, unsigned size)
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EXPORT_SYMBOL_GPL(hid_parse_report);
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EXPORT_SYMBOL_GPL(hid_parse_report);
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static const char * const hid_report_names[] = {
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"HID_INPUT_REPORT",
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"HID_OUTPUT_REPORT",
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"HID_FEATURE_REPORT",
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};
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/**
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* hid_validate_values - validate existing device report's value indexes
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*
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* @device: hid device
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* @type: which report type to examine
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* @id: which report ID to examine (0 for first)
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* @field_index: which report field to examine
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* @report_counts: expected number of values
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*
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* Validate the number of values in a given field of a given report, after
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* parsing.
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*/
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struct hid_report *hid_validate_values(struct hid_device *hid,
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unsigned int type, unsigned int id,
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unsigned int field_index,
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unsigned int report_counts)
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{
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struct hid_report *report;
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if (type > HID_FEATURE_REPORT) {
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hid_err(hid, "invalid HID report type %u\n", type);
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return NULL;
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}
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if (id >= HID_MAX_IDS) {
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hid_err(hid, "invalid HID report id %u\n", id);
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return NULL;
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}
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/*
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* Explicitly not using hid_get_report() here since it depends on
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* ->numbered being checked, which may not always be the case when
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* drivers go to access report values.
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*/
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report = hid->report_enum[type].report_id_hash[id];
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if (!report) {
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hid_err(hid, "missing %s %u\n", hid_report_names[type], id);
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return NULL;
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}
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if (report->maxfield <= field_index) {
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hid_err(hid, "not enough fields in %s %u\n",
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hid_report_names[type], id);
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return NULL;
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}
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if (report->field[field_index]->report_count < report_counts) {
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hid_err(hid, "not enough values in %s %u field %u\n",
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hid_report_names[type], id, field_index);
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return NULL;
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}
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return report;
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}
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EXPORT_SYMBOL_GPL(hid_validate_values);
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/**
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/**
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* hid_open_report - open a driver-specific device report
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* hid_open_report - open a driver-specific device report
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*
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*
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@@ -756,6 +756,10 @@ u8 *hid_alloc_report_buf(struct hid_report *report, gfp_t flags);
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struct hid_device *hid_allocate_device(void);
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struct hid_device *hid_allocate_device(void);
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struct hid_report *hid_register_report(struct hid_device *device, unsigned type, unsigned id);
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struct hid_report *hid_register_report(struct hid_device *device, unsigned type, unsigned id);
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int hid_parse_report(struct hid_device *hid, __u8 *start, unsigned size);
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int hid_parse_report(struct hid_device *hid, __u8 *start, unsigned size);
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struct hid_report *hid_validate_values(struct hid_device *hid,
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unsigned int type, unsigned int id,
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unsigned int field_index,
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unsigned int report_counts);
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int hid_open_report(struct hid_device *device);
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int hid_open_report(struct hid_device *device);
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int hid_check_keys_pressed(struct hid_device *hid);
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int hid_check_keys_pressed(struct hid_device *hid);
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int hid_connect(struct hid_device *hid, unsigned int connect_mask);
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int hid_connect(struct hid_device *hid, unsigned int connect_mask);
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