cfg80211: remove unused function ieee80211_data_from_8023()

This function hasn't been used since the removal of iwmc3200wifi
in 2012. It also appears to have a bug when qos=True, since then
it'll copy uninitialized stack memory to the SKB.

Just remove the function entirely.
Reported-by: Jouni Malinen <j@w1.fi>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

Documentation/driver-api/80211/cfg80211.rst

@@ -299,9 +299,6 @@ Data path helpers
 .. kernel-doc:: include/net/cfg80211.h
    :functions: ieee80211_data_to_8023
 
-.. kernel-doc:: include/net/cfg80211.h
-   :functions: ieee80211_data_from_8023
-
 .. kernel-doc:: include/net/cfg80211.h
    :functions: ieee80211_amsdu_to_8023s
 

include/net/cfg80211.h

@@ -4346,19 +4346,6 @@ static inline int ieee80211_data_to_8023(struct sk_buff *skb, const u8 *addr,
 	return ieee80211_data_to_8023_exthdr(skb, NULL, addr, iftype);
 }
 
-/**
- * ieee80211_data_from_8023 - convert an 802.3 frame to 802.11
- * @skb: the 802.3 frame
- * @addr: the device MAC address
- * @iftype: the virtual interface type
- * @bssid: the network bssid (used only for iftype STATION and ADHOC)
- * @qos: build 802.11 QoS data frame
- * Return: 0 on success, or a negative error code.
- */
-int ieee80211_data_from_8023(struct sk_buff *skb, const u8 *addr,
-			     enum nl80211_iftype iftype, const u8 *bssid,
-			     bool qos);
-
 /**
  * ieee80211_amsdu_to_8023s - decode an IEEE 802.11n A-MSDU frame
  *

net/wireless/util.c

@@ -529,121 +529,6 @@ int ieee80211_data_to_8023_exthdr(struct sk_buff *skb, struct ethhdr *ehdr,
 }
 EXPORT_SYMBOL(ieee80211_data_to_8023_exthdr);
 
-int ieee80211_data_from_8023(struct sk_buff *skb, const u8 *addr,
-			     enum nl80211_iftype iftype,
-			     const u8 *bssid, bool qos)
-{
-	struct ieee80211_hdr hdr;
-	u16 hdrlen, ethertype;
-	__le16 fc;
-	const u8 *encaps_data;
-	int encaps_len, skip_header_bytes;
-	int nh_pos, h_pos;
-	int head_need;
-
-	if (unlikely(skb->len < ETH_HLEN))
-		return -EINVAL;
-
-	nh_pos = skb_network_header(skb) - skb->data;
-	h_pos = skb_transport_header(skb) - skb->data;
-
-	/* convert Ethernet header to proper 802.11 header (based on
-	 * operation mode) */
-	ethertype = (skb->data[12] << 8) | skb->data[13];
-	fc = cpu_to_le16(IEEE80211_FTYPE_DATA | IEEE80211_STYPE_DATA);
-
-	switch (iftype) {
-	case NL80211_IFTYPE_AP:
-	case NL80211_IFTYPE_AP_VLAN:
-	case NL80211_IFTYPE_P2P_GO:
-		fc |= cpu_to_le16(IEEE80211_FCTL_FROMDS);
-		/* DA BSSID SA */
-		memcpy(hdr.addr1, skb->data, ETH_ALEN);
-		memcpy(hdr.addr2, addr, ETH_ALEN);
-		memcpy(hdr.addr3, skb->data + ETH_ALEN, ETH_ALEN);
-		hdrlen = 24;
-		break;
-	case NL80211_IFTYPE_STATION:
-	case NL80211_IFTYPE_P2P_CLIENT:
-		fc |= cpu_to_le16(IEEE80211_FCTL_TODS);
-		/* BSSID SA DA */
-		memcpy(hdr.addr1, bssid, ETH_ALEN);
-		memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
-		memcpy(hdr.addr3, skb->data, ETH_ALEN);
-		hdrlen = 24;
-		break;
-	case NL80211_IFTYPE_OCB:
-	case NL80211_IFTYPE_ADHOC:
-		/* DA SA BSSID */
-		memcpy(hdr.addr1, skb->data, ETH_ALEN);
-		memcpy(hdr.addr2, skb->data + ETH_ALEN, ETH_ALEN);
-		memcpy(hdr.addr3, bssid, ETH_ALEN);
-		hdrlen = 24;
-		break;
-	default:
-		return -EOPNOTSUPP;
-	}
-
-	if (qos) {
-		fc |= cpu_to_le16(IEEE80211_STYPE_QOS_DATA);
-		hdrlen += 2;
-	}
-
-	hdr.frame_control = fc;
-	hdr.duration_id = 0;
-	hdr.seq_ctrl = 0;
-
-	skip_header_bytes = ETH_HLEN;
-	if (ethertype == ETH_P_AARP || ethertype == ETH_P_IPX) {
-		encaps_data = bridge_tunnel_header;
-		encaps_len = sizeof(bridge_tunnel_header);
-		skip_header_bytes -= 2;
-	} else if (ethertype >= ETH_P_802_3_MIN) {
-		encaps_data = rfc1042_header;
-		encaps_len = sizeof(rfc1042_header);
-		skip_header_bytes -= 2;
-	} else {
-		encaps_data = NULL;
-		encaps_len = 0;
-	}
-
-	skb_pull(skb, skip_header_bytes);
-	nh_pos -= skip_header_bytes;
-	h_pos -= skip_header_bytes;
-
-	head_need = hdrlen + encaps_len - skb_headroom(skb);
-
-	if (head_need > 0 || skb_cloned(skb)) {
-		head_need = max(head_need, 0);
-		if (head_need)
-			skb_orphan(skb);
-
-		if (pskb_expand_head(skb, head_need, 0, GFP_ATOMIC))
-			return -ENOMEM;
-	}
-
-	if (encaps_data) {
-		memcpy(skb_push(skb, encaps_len), encaps_data, encaps_len);
-		nh_pos += encaps_len;
-		h_pos += encaps_len;
-	}
-
-	memcpy(skb_push(skb, hdrlen), &hdr, hdrlen);
-
-	nh_pos += hdrlen;
-	h_pos += hdrlen;
-
-	/* Update skb pointers to various headers since this modified frame
-	 * is going to go through Linux networking code that may potentially
-	 * need things like pointer to IP header. */
-	skb_reset_mac_header(skb);
-	skb_set_network_header(skb, nh_pos);
-	skb_set_transport_header(skb, h_pos);
-
-	return 0;
-}
-EXPORT_SYMBOL(ieee80211_data_from_8023);
-
 static void
 __frame_add_frag(struct sk_buff *skb, struct page *page,
 		 void *ptr, int len, int size)