by Greenman, Gregory

[permalink] [raw]

Subject: [PATCH 16/20] wifi: cfg80211: add element defragmentation helper

From: Benjamin Berg <[email protected]>

This is already needed within mac80211 and support is also needed by
cfg80211 to parse ML elements.

Signed-off-by: Benjamin Berg <[email protected]>
Signed-off-by: Gregory Greenman <[email protected]>
---
include/net/cfg80211.h | 22 ++++++++++++++++
net/wireless/scan.c | 60 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 82 insertions(+)

diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index 94ca5cb340f6..cf14a93e61eb 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -6664,6 +6664,28 @@ cfg80211_find_vendor_ie(unsigned int oui, int oui_type,
return (const void *)cfg80211_find_vendor_elem(oui, oui_type, ies, len);
}

+/**
+ * cfg80211_defragment_element - Defrag the given element data into a buffer
+ *
+ * @elem: the element to defragment
+ * @ies: elements where @elem is contained
+ * @ieslen: length of @ies
+ * @data: buffer to store element data
+ * @data_len: length of @data
+ * @frag_id: the element ID of fragments
+ *
+ * Return: length of @data, or -EINVAL on error
+ *
+ * Copy out all data from an element that may be fragmented into @data, while
+ * skipping all headers.
+ *
+ * The function uses memmove() internally. It is acceptable to defragment an
+ * element in-place.
+ */
+ssize_t cfg80211_defragment_element(const struct element *elem, const u8 *ies,
+ size_t ieslen, u8 *data, size_t data_len,
+ u8 frag_id);
+
/**
* cfg80211_send_layer2_update - send layer 2 update frame
*
diff --git a/net/wireless/scan.c b/net/wireless/scan.c
index 75e6e032bb3a..dc71c6ac5bf5 100644
--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -2288,6 +2288,66 @@ static void cfg80211_parse_mbssid_data(struct wiphy *wiphy,
kfree(profile);
}

+ssize_t cfg80211_defragment_element(const struct element *elem, const u8 *ies,
+ size_t ieslen, u8 *data, size_t data_len,
+ u8 frag_id)
+{
+ const struct element *next;
+ ssize_t copied;
+ u8 elem_datalen;
+
+ if (!elem)
+ return -EINVAL;
+
+ /* elem might be invalid after the memmove */
+ next = (void *)(elem->data + elem->datalen);
+
+ elem_datalen = elem->datalen;
+ if (elem->id == WLAN_EID_EXTENSION) {
+ copied = elem->datalen - 1;
+ if (copied > data_len)
+ return -ENOSPC;
+
+ memmove(data, elem->data + 1, copied);
+ } else {
+ copied = elem->datalen;
+ if (copied > data_len)
+ return -ENOSPC;
+
+ memmove(data, elem->data, copied);
+ }
+
+ /* Fragmented elements must have 255 bytes */
+ if (elem_datalen < 255)
+ return copied;
+
+ for (elem = next;
+ elem->data < ies + ieslen &&
+ elem->data + elem->datalen < ies + ieslen;
+ elem = next) {
+ /* elem might be invalid after the memmove */
+ next = (void *)(elem->data + elem->datalen);
+
+ if (elem->id != frag_id)
+ break;
+
+ elem_datalen = elem->datalen;
+
+ if (copied + elem_datalen > data_len)
+ return -ENOSPC;
+
+ memmove(data + copied, elem->data, elem_datalen);
+ copied += elem_datalen;
+
+ /* Only the last fragment may be short */
+ if (elem_datalen != 255)
+ break;
+ }
+
+ return copied;
+}
+EXPORT_SYMBOL(cfg80211_defragment_element);
+
struct cfg80211_bss *
cfg80211_inform_bss_data(struct wiphy *wiphy,
struct cfg80211_inform_bss *data,
--
2.38.1