On 2016-10-13 07:41, Michael Braun wrote:
> According to IEEE 802.11-2012 section 8.3.2 table 8-19, the outer SA/DA
> of A-MSDU frames need to be changed depending on FromDS/ToDS values.
> 
> Signed-off-by: Michael Braun <michael-...@fami-braun.de>
> 
> --
> v4:
>  - h_80211_src/dst has been memmove'd and thus needs to be fixed
> v3:
>  - write to outer 802.11 header instead of inner amsdu subframe header
> v2:
>  - avoid the extra write to amsdu_hdr
>  - avoid copy of asmdu_hdr into skb, use ptr instead
> ---
>  net/mac80211/tx.c | 46 ++++++++++++++++++++++++++++++++++++----------
>  1 file changed, 36 insertions(+), 10 deletions(-)
> 
> diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
> index 5023966..5f80b94 100644
> --- a/net/mac80211/tx.c
> +++ b/net/mac80211/tx.c
> @@ -3058,19 +3059,44 @@ static bool ieee80211_amsdu_prepare_head(struct 
> ieee80211_sub_if_data *sdata,
>       if (info->control.flags & IEEE80211_TX_CTRL_AMSDU)
>               return true;
>  
> -     if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(amsdu_hdr),
> +     if (!ieee80211_amsdu_realloc_pad(local, skb, sizeof(*amsdu_hdr),
>                                        &subframe_len))
>               return false;
>  
> -     amsdu_hdr.h_proto = cpu_to_be16(subframe_len);
> -     memcpy(amsdu_hdr.h_source, skb->data + fast_tx->sa_offs, ETH_ALEN);
> -     memcpy(amsdu_hdr.h_dest, skb->data + fast_tx->da_offs, ETH_ALEN);
> +     data = skb_push(skb, sizeof(*amsdu_hdr));
> +     memmove(data, data + sizeof(*amsdu_hdr), hdr_len);
> +     hdr = data;
> +     amsdu_hdr = data + hdr_len;
> +     /* h_80211_src/dst is addr* field within hdr */
> +     h_80211_src = data + fast_tx->sa_offs;
> +     h_80211_dst = data + fast_tx->da_offs;
> +
> +     amsdu_hdr->h_proto = cpu_to_be16(subframe_len);
> +     memcpy(amsdu_hdr->h_source, h_80211_src, ETH_ALEN);
> +     memcpy(amsdu_hdr->h_dest, h_80211_dst, ETH_ALEN);
> +
> +     /* according to IEEE 802.11-2012 8.3.2 table 8-19, the outer SA/DA
> +      * fields needs to be changed to BSSID for A-MSDU frames depending
> +      * on FromDS/ToDS values.
> +      */
> +     switch (sdata->vif.type) {
> +     case NL80211_IFTYPE_STATION:
> +             bssid = sdata->u.mgd.bssid;
> +             break;
> +     case NL80211_IFTYPE_AP:
> +     case NL80211_IFTYPE_AP_VLAN:
> +             bssid = sdata->vif.addr;
> +             break;
> +     default:
> +             bssid = NULL;
> +     }
>  
> -     data = skb_push(skb, sizeof(amsdu_hdr));
> -     memmove(data, data + sizeof(amsdu_hdr), hdr_len);
> -     memcpy(data + hdr_len, &amsdu_hdr, sizeof(amsdu_hdr));
> +     if (bssid && ieee80211_has_fromds(hdr->frame_control))
> +             memcpy(h_80211_src, bssid, ETH_ALEN);
> +
> +     if (bssid && ieee80211_has_tods(hdr->frame_control))
> +             memcpy(h_80211_dst, bssid, ETH_ALEN);
I think this is probably wrong for 4-addr, since there both FromDS and
ToDS are set. Maybe you should use !ieee80211_has_tods instead of
ieee80211_has_fromds and vice versa.

- Felix

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