Return-Path: MIME-Version: 1.0 In-Reply-To: <7f9a9a39-fbe4-c577-3b8b-e8350634ddcb@pengutronix.de> References: <20170209145551.12747-1-luiz.dentz@gmail.com> <20170209145551.12747-6-luiz.dentz@gmail.com> <7f9a9a39-fbe4-c577-3b8b-e8350634ddcb@pengutronix.de> From: Luiz Augusto von Dentz Date: Wed, 15 Feb 2017 10:24:02 +0200 Message-ID: Subject: Re: [PATCH 5/5] 6lowpan: Use netdev addr_len to determine lladdr len To: Alexander Aring Cc: "linux-bluetooth@vger.kernel.org" , Patrik Flykt Content-Type: text/plain; charset=UTF-8 Sender: linux-bluetooth-owner@vger.kernel.org List-ID: Hi Alex, On Wed, Feb 15, 2017 at 9:44 AM, Alexander Aring wrote: > > Hi, > > On 02/09/2017 03:55 PM, Luiz Augusto von Dentz wrote: >> From: Luiz Augusto von Dentz >> >> This allow technologies such as Bluetooth to use its native lladdr which >> is eui48 instead of eui64 which was expected by functions like >> lowpan_header_decompress and lowpan_header_compress. >> >> Signed-off-by: Luiz Augusto von Dentz >> --- >> net/6lowpan/iphc.c | 17 +++++++++++++++-- >> net/bluetooth/6lowpan.c | 43 ++++++++++--------------------------------- >> 2 files changed, 25 insertions(+), 35 deletions(-) >> >> diff --git a/net/6lowpan/iphc.c b/net/6lowpan/iphc.c >> index fb5f6fa..ee88feb 100644 >> --- a/net/6lowpan/iphc.c >> +++ b/net/6lowpan/iphc.c >> @@ -827,8 +827,21 @@ static u8 lowpan_compress_ctx_addr(u8 **hc_ptr, const struct net_device *dev, >> } >> break; >> default: >> - /* check for SAM/DAM = 11 */ >> - memcpy(&tmp.s6_addr[8], lladdr, EUI64_ADDR_LEN); >> + switch (dev->addr_len) { >> + case ETH_ALEN: >> + memcpy(&tmp.s6_addr[8], lladdr, 3); >> + tmp.s6_addr[11] = 0xFF; >> + tmp.s6_addr[12] = 0xFE; >> + memcpy(&tmp.s6_addr[13], lladdr + 3, 3); >> + break; >> + case EUI64_ADDR_LEN: >> + memcpy(&tmp.s6_addr[8], lladdr, EUI64_ADDR_LEN); >> + break; >> + default: >> + dam = LOWPAN_IPHC_DAM_11; >> + goto out; >> + } >> + >> /* second bit-flip (Universe/Local) is done according RFC2464 */ >> tmp.s6_addr[8] ^= 0x02; > > move this handling in per link-layer layer decision, see below. > >> /* context information are always used */ > > PLEASE... and this is one of my rant! > > PLEASE LOOK WHAT I HAVE DONE IN THIS FILE IN MY RFC PATCH SERIES YOU > NEED TO FIX MORE THAN JUST CONTEXT BASED COMPRESSION. > > e.g. stateless un/compression I haven't changed that and probably it needs a separate patch in that case since Im only, and I really mean only, fixing the address length and because your patches end up changing a lot more things it is pretty hard to extract the exact parts that fixes this. > Now I for this, I want to see a link-layer evaluation not address length based. > Please do so also for the other patch which fixing some behaviour in ipv6. > The reason is here that uncompress/compress addresses are defined by RFC > 6LoWPAN adapation. > > There is already a link-layer case, so please add BTLE LLTYPE there! Not > move your handling in default, add some WARN_ONCE there... Here I have to pretty blunt, it is a mistake to put link layer logic inside the 6lowpan module, first it creates a dependencies of these technologies and second it slow down the development because we end up with multiple trees having to synchronize which each other. Also I have not seen a single mention of link local IP that is not using 6 or 8 bytes link layer format, and in fact if there exist one then we should probably have the caller handle the link local ip format, but then again I haven't seen any indication that these needs changing in fact for 15.4 16 bit address you can generate a valid 8 bytes address before calling 6lowpan API, which is probably what we should do to avoid depending on 15.4 code inside 6lowpan. > btw: > > here exists also a cleanup to not always implement the same stuff. We > need for stateful/stateless compression one function, because and > remember my words if you want to make this cleanup: > > Stateless compression is stateful compression with prefix fe80::/64 as > context. > > --- > > Sorry for my rant, but I am somehow pissed off because intel people > doesn't look what I did there in my RFC. > > ... I think now I know why linux kernel people do sometimes a rant. :-) > > Thanks. > >> diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c >> index 1456b01..d2a1aa5 100644 >> --- a/net/bluetooth/6lowpan.c >> +++ b/net/bluetooth/6lowpan.c >> @@ -64,7 +64,7 @@ struct lowpan_peer { >> struct l2cap_chan *chan; >> >> /* peer addresses in various formats */ >> - unsigned char eui64_addr[EUI64_ADDR_LEN]; >> + unsigned char lladdr[ETH_ALEN]; >> struct in6_addr peer_addr; >> }; >> >> @@ -80,8 +80,6 @@ struct lowpan_btle_dev { >> struct delayed_work notify_peers; >> }; >> >> -static void set_addr(u8 *eui, u8 *addr, u8 addr_type); >> - >> static inline struct lowpan_btle_dev * >> lowpan_btle_dev(const struct net_device *netdev) >> { >> @@ -277,7 +275,6 @@ static int iphc_decompress(struct sk_buff *skb, struct net_device *netdev, >> const u8 *saddr; >> struct lowpan_btle_dev *dev; >> struct lowpan_peer *peer; >> - unsigned char eui64_daddr[EUI64_ADDR_LEN]; >> >> dev = lowpan_btle_dev(netdev); >> >> @@ -287,10 +284,9 @@ static int iphc_decompress(struct sk_buff *skb, struct net_device *netdev, >> if (!peer) >> return -EINVAL; >> >> - saddr = peer->eui64_addr; >> - set_addr(&eui64_daddr[0], chan->src.b, chan->src_type); >> + saddr = peer->lladdr; >> >> - return lowpan_header_decompress(skb, netdev, &eui64_daddr, saddr); >> + return lowpan_header_decompress(skb, netdev, netdev->dev_addr, saddr); > > This looks not right, you are sure that netdev->dev_addr is the > _destination_ address? It looks very confusing, because dev_addr is > normally the source address of the netdevice interface. > >> } >> >> static int recv_pkt(struct sk_buff *skb, struct net_device *dev, >> @@ -477,7 +473,7 @@ static int setup_header(struct sk_buff *skb, struct net_device *netdev, >> } >> } >> >> - daddr = peer->eui64_addr; >> + daddr = peer->lladdr; >> *peer_addr = addr; >> *peer_addr_type = addr_type; >> lowpan_cb(skb)->chan = peer->chan; >> @@ -663,27 +659,6 @@ static struct device_type bt_type = { >> .name = "bluetooth", >> }; >> >> -static void set_addr(u8 *eui, u8 *addr, u8 addr_type) >> -{ >> - /* addr is the BT address in little-endian format */ >> - eui[0] = addr[5]; >> - eui[1] = addr[4]; >> - eui[2] = addr[3]; >> - eui[3] = 0xFF; >> - eui[4] = 0xFE; >> - eui[5] = addr[2]; >> - eui[6] = addr[1]; >> - eui[7] = addr[0]; >> - >> - /* Universal/local bit set, BT 6lowpan draft ch. 3.2.1 */ >> - if (addr_type == BDADDR_LE_PUBLIC) >> - eui[0] &= ~0x02; >> - else >> - eui[0] |= 0x02; >> - >> - BT_DBG("type %d addr %*phC", addr_type, 8, eui); >> -} >> - > > YAY, this function is totally wrong! :-) > >> static void ifup(struct net_device *netdev) >> { >> int err; >> @@ -762,14 +737,16 @@ static struct l2cap_chan *add_peer_chan(struct l2cap_chan *chan, >> peer->chan = chan; >> memset(&peer->peer_addr, 0, sizeof(struct in6_addr)); >> >> + baswap((void *)peer->lladdr, &chan->dst); >> + >> /* RFC 2464 ch. 5 */ >> peer->peer_addr.s6_addr[0] = 0xFE; >> peer->peer_addr.s6_addr[1] = 0x80; >> - set_addr((u8 *)&peer->peer_addr.s6_addr + 8, chan->dst.b, >> - chan->dst_type); >> >> - memcpy(&peer->eui64_addr, (u8 *)&peer->peer_addr.s6_addr + 8, >> - EUI64_ADDR_LEN); >> + memcpy(&peer->peer_addr.s6_addr[8], peer->lladdr, 3); >> + peer->peer_addr.s6_addr[11] = 0xFF; >> + peer->peer_addr.s6_addr[12] = 0xFE; >> + memcpy(&peer->peer_addr.s6_addr[13], peer->lladdr + 3, 3); >> > > What the hell is that? I suppose this is to handling something correct > to a behaviour which is another big thing which is totally broken in the > BTLE 6LoWPAN code. > >> /* IPv6 address needs to have the U/L bit set properly so toggle >> * it back here. >> > > - Alex -- Luiz Augusto von Dentz