Merge branch '6lowpan-ndisc'

Alexander Aring says:

====================
6lowpan: introduce 6lowpan-nd

David can you please pick-up this patch-serie for your net-next tree?
Thanks in advance.

This patch series introduces the ndisc ops callback structure to add different
handling for IPv6 neighbour discovery cache functionality. It implements at first
the two following use-cases:

 - 6CO handling as userspace option (For all 6LoWPAN layers, BTLE/802.15.4) [0]
 - short address handling for 802.15.4 6LoWPAN only [1]

Since my last patch series, I completely changed the whole ndisc_ops callback
structure to not replace the whole ndisc functionality at recv/send level of
NS/NA/RS/RA which I send in my previous patch-series "6lowpan: introduce basic
6lowpan-nd". I changed it now to add different handling in a very low-level way
of ndisc functionality.

The ndisc_ops don't must be registered to dev->ndisc_ops anymore, if they are not
set, then no additional ipv6 ndisc handling will be done.

This patch series now introduce a complete handling of short address for
802.15.4 6LoWPAN in case of send/recv of NA/NS/RS and RA. In case of RA
(receive only) and PIO we also need a second prefix + short-address based
address.

This callback structure can be used later (I hope) for RFC 6775 [0]. This RFC
defines some new option fields and messages for 6LoWPAN-ND. This patch series
does not implement RFC 6775 (except we decide now to handle 6CO in userspace).

Additional we can use the current ops for parse/fill ndisc options for kernel
handled ndisc messages to add 6CIO, see [2].

I tested RA/NS/NA/RS messages with short address which seems to work, what I
didn't test is the redirect messages since I don't know how to generate them.
The short address for redirect messages are also some special case here, because
the short address by a L3 target address lookuped by neighbour cache need to be
added.

btw:
According to [3] sending redirect messages should be also disabled by default
on 6lowpan interfaces, but can be activated afterwards. This is maybe
something for the ipv6_devconf structure. There is a "accept_redirects" but
no "disable_redirects".

- Alex

[0] https://tools.ietf.org/html/rfc6775
[1] https://tools.ietf.org/html/rfc4944#section-8
[2] https://tools.ietf.org/html/rfc7400

changes since v3:
 - add acked-by and reviewed-by tags
 - fix url references in cover-letter
 - add cover-letter that this patch series is okay to go through net-next tree

changes since RFC:
 - add lowlevel functions __ndisc_opt_addr_space,
   __ndisc_opt_addr_data and __ndisc_fill_addr_option for corresponding
   functions which doesn't requires net_device argument.
 - move ndisc_ops e.g. ndisc_ops_fill_addr_option function call into the
   corresponding device argument function ndisc_fill_addr_option.
   (Introduced a special static inline function for redirect handling).
 - fix error handling in addrconf_prefix_rcv_add_addr.
   (Please see, introduce new API handling that second address registration
    (in case of 802.15.4 6LoWPAN) will still be notified if failed, because
    dev->addr was successful.
 - add ieee802154 sub-directory in short address entry for 6lowpan UAPI.
 - add lowpan_802154_is_valid_src_short_addr, because 802.15.4 6lowpan
   defines the first bit as multicast (don't know how this can be working
   at the end, because some hardware addresses will handle such addresses
   in L2 as unicast. See:
   https://www.iana.org/assignments/_6lowpan-parameters/_6lowpan-parameters.xhtml#_6lowpan-parameters-2

changes since v2:
 - Introduce ndisc_ops to have our own implementation for dealing with NS/NA
   which allows also to support RFC6775 (e.g. ARO).
 - add handling for handling 6CO as userspace option for RA messages in
   case of 6LoWPAN interfaces.
 - change lowpan_is_ll to check on linklayer type only.
 - added some reviewed-by's.
 - move short addr slaac to net/6lowpan instead ipv6 handling.
 - add handling for context based address compression in case for
   short address as link-layer address.
 - change strategy to use short address, a short address will always be used
   when it's available.
 - Handle override flag in NA messages to update short address information or
   not.
====================

Acked-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 266 insertions, 16 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index d101e4d904ba..890158e99159 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1456,6 +1456,8 @@ enum netdev_priv_flags {
  *	@netdev_ops:	Includes several pointers to callbacks,
  *			if one wants to override the ndo_*() functions
  *	@ethtool_ops:	Management operations
+ *	@ndisc_ops:	Includes callbacks for different IPv6 neighbour
+ *			discovery handling. Necessary for e.g. 6LoWPAN.
  *	@header_ops:	Includes callbacks for creating,parsing,caching,etc
  *			of Layer 2 headers.
  *
@@ -1483,8 +1485,7 @@ enum netdev_priv_flags {
  * 	@perm_addr:		Permanent hw address
  * 	@addr_assign_type:	Hw address assignment type
  * 	@addr_len:		Hardware address length
- * 	@neigh_priv_len;	Used in neigh_alloc(),
- * 				initialized only in atm/clip.c
+ *	@neigh_priv_len:	Used in neigh_alloc()
  * 	@dev_id:		Used to differentiate devices that share
  * 				the same link layer address
  * 	@dev_port:		Used to differentiate devices that share
@@ -1673,6 +1674,9 @@ struct net_device {
 #ifdef CONFIG_NET_L3_MASTER_DEV
 	const struct l3mdev_ops	*l3mdev_ops;
 #endif
+#if IS_ENABLED(CONFIG_IPV6)
+	const struct ndisc_ops *ndisc_ops;
+#endif
 
 	const struct header_ops *header_ops;
 
diff --git a/include/net/6lowpan.h b/include/net/6lowpan.h
index da84cf920b78..5ab4c9901ccc 100644
--- a/include/net/6lowpan.h
+++ b/include/net/6lowpan.h
@@ -141,6 +141,16 @@ struct lowpan_dev {
 	u8 priv[0] __aligned(sizeof(void *));
 };
 
+struct lowpan_802154_neigh {
+	__le16 short_addr;
+};
+
+static inline
+struct lowpan_802154_neigh *lowpan_802154_neigh(void *neigh_priv)
+{
+	return neigh_priv;
+}
+
 static inline
 struct lowpan_dev *lowpan_dev(const struct net_device *dev)
 {
@@ -244,6 +254,12 @@ static inline bool lowpan_fetch_skb(struct sk_buff *skb, void *data,
 	return false;
 }
 
+static inline bool lowpan_802154_is_valid_src_short_addr(__le16 addr)
+{
+	/* First bit of addr is multicast, reserved or 802.15.4 specific */
+	return !(addr & cpu_to_le16(0x8000));
+}
+
 static inline void lowpan_push_hc_data(u8 **hc_ptr, const void *data,
 				       const size_t len)
 {
diff --git a/include/net/addrconf.h b/include/net/addrconf.h
index 730d856683e5..9826d3a9464c 100644
--- a/include/net/addrconf.h
+++ b/include/net/addrconf.h
@@ -94,6 +94,16 @@ int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
 void addrconf_join_solict(struct net_device *dev, const struct in6_addr *addr);
 void addrconf_leave_solict(struct inet6_dev *idev, const struct in6_addr *addr);
 
+void addrconf_add_linklocal(struct inet6_dev *idev,
+			    const struct in6_addr *addr, u32 flags);
+
+int addrconf_prefix_rcv_add_addr(struct net *net, struct net_device *dev,
+				 const struct prefix_info *pinfo,
+				 struct inet6_dev *in6_dev,
+				 const struct in6_addr *addr, int addr_type,
+				 u32 addr_flags, bool sllao, bool tokenized,
+				 __u32 valid_lft, u32 prefered_lft);
+
 static inline int addrconf_ifid_eui48(u8 *eui, struct net_device *dev)
 {
 	if (dev->addr_len != ETH_ALEN)
diff --git a/include/net/ndisc.h b/include/net/ndisc.h
index 2d8edaad29cb..be1fe2283254 100644
--- a/include/net/ndisc.h
+++ b/include/net/ndisc.h
@@ -35,6 +35,7 @@ enum {
 	ND_OPT_ROUTE_INFO = 24,		/* RFC4191 */
 	ND_OPT_RDNSS = 25,		/* RFC5006 */
 	ND_OPT_DNSSL = 31,		/* RFC6106 */
+	ND_OPT_6CO = 34,		/* RFC6775 */
 	__ND_OPT_MAX
 };
 
@@ -53,11 +54,21 @@ enum {
 
 #include <net/neighbour.h>
 
+/* Set to 3 to get tracing... */
+#define ND_DEBUG 1
+
+#define ND_PRINTK(val, level, fmt, ...)				\
+do {								\
+	if (val <= ND_DEBUG)					\
+		net_##level##_ratelimited(fmt, ##__VA_ARGS__);	\
+} while (0)
+
 struct ctl_table;
 struct inet6_dev;
 struct net_device;
 struct net_proto_family;
 struct sk_buff;
+struct prefix_info;
 
 extern struct neigh_table nd_tbl;
 
@@ -99,20 +110,201 @@ struct ndisc_options {
 #endif
 	struct nd_opt_hdr *nd_useropts;
 	struct nd_opt_hdr *nd_useropts_end;
+#if IS_ENABLED(CONFIG_IEEE802154_6LOWPAN)
+	struct nd_opt_hdr *nd_802154_opt_array[ND_OPT_TARGET_LL_ADDR + 1];
+#endif
 };
 
-#define nd_opts_src_lladdr	nd_opt_array[ND_OPT_SOURCE_LL_ADDR]
-#define nd_opts_tgt_lladdr	nd_opt_array[ND_OPT_TARGET_LL_ADDR]
-#define nd_opts_pi		nd_opt_array[ND_OPT_PREFIX_INFO]
-#define nd_opts_pi_end		nd_opt_array[__ND_OPT_PREFIX_INFO_END]
-#define nd_opts_rh		nd_opt_array[ND_OPT_REDIRECT_HDR]
-#define nd_opts_mtu		nd_opt_array[ND_OPT_MTU]
+#define nd_opts_src_lladdr		nd_opt_array[ND_OPT_SOURCE_LL_ADDR]
+#define nd_opts_tgt_lladdr		nd_opt_array[ND_OPT_TARGET_LL_ADDR]
+#define nd_opts_pi			nd_opt_array[ND_OPT_PREFIX_INFO]
+#define nd_opts_pi_end			nd_opt_array[__ND_OPT_PREFIX_INFO_END]
+#define nd_opts_rh			nd_opt_array[ND_OPT_REDIRECT_HDR]
+#define nd_opts_mtu			nd_opt_array[ND_OPT_MTU]
+#define nd_802154_opts_src_lladdr	nd_802154_opt_array[ND_OPT_SOURCE_LL_ADDR]
+#define nd_802154_opts_tgt_lladdr	nd_802154_opt_array[ND_OPT_TARGET_LL_ADDR]
 
 #define NDISC_OPT_SPACE(len) (((len)+2+7)&~7)
 
-struct ndisc_options *ndisc_parse_options(u8 *opt, int opt_len,
+struct ndisc_options *ndisc_parse_options(const struct net_device *dev,
+					  u8 *opt, int opt_len,
 					  struct ndisc_options *ndopts);
 
+void __ndisc_fill_addr_option(struct sk_buff *skb, int type, void *data,
+			      int data_len, int pad);
+
+#define NDISC_OPS_REDIRECT_DATA_SPACE	2
+
+/*
+ * This structure defines the hooks for IPv6 neighbour discovery.
+ * The following hooks can be defined; unless noted otherwise, they are
+ * optional and can be filled with a null pointer.
+ *
+ * int (*is_useropt)(u8 nd_opt_type):
+ *     This function is called when IPv6 decide RA userspace options. if
+ *     this function returns 1 then the option given by nd_opt_type will
+ *     be handled as userspace option additional to the IPv6 options.
+ *
+ * int (*parse_options)(const struct net_device *dev,
+ *			struct nd_opt_hdr *nd_opt,
+ *			struct ndisc_options *ndopts):
+ *     This function is called while parsing ndisc ops and put each position
+ *     as pointer into ndopts. If this function return unequal 0, then this
+ *     function took care about the ndisc option, if 0 then the IPv6 ndisc
+ *     option parser will take care about that option.
+ *
+ * void (*update)(const struct net_device *dev, struct neighbour *n,
+ *		  u32 flags, u8 icmp6_type,
+ *		  const struct ndisc_options *ndopts):
+ *     This function is called when IPv6 ndisc updates the neighbour cache
+ *     entry. Additional options which can be updated may be previously
+ *     parsed by parse_opts callback and accessible over ndopts parameter.
+ *
+ * int (*opt_addr_space)(const struct net_device *dev, u8 icmp6_type,
+ *			 struct neighbour *neigh, u8 *ha_buf,
+ *			 u8 **ha):
+ *     This function is called when the necessary option space will be
+ *     calculated before allocating a skb. The parameters neigh, ha_buf
+ *     abd ha are available on NDISC_REDIRECT messages only.
+ *
+ * void (*fill_addr_option)(const struct net_device *dev,
+ *			    struct sk_buff *skb, u8 icmp6_type,
+ *			    const u8 *ha):
+ *     This function is called when the skb will finally fill the option
+ *     fields inside skb. NOTE: this callback should fill the option
+ *     fields to the skb which are previously indicated by opt_space
+ *     parameter. That means the decision to add such option should
+ *     not lost between these two callbacks, e.g. protected by interface
+ *     up state.
+ *
+ * void (*prefix_rcv_add_addr)(struct net *net, struct net_device *dev,
+ *			       const struct prefix_info *pinfo,
+ *			       struct inet6_dev *in6_dev,
+ *			       struct in6_addr *addr,
+ *			       int addr_type, u32 addr_flags,
+ *			       bool sllao, bool tokenized,
+ *			       __u32 valid_lft, u32 prefered_lft,
+ *			       bool dev_addr_generated):
+ *     This function is called when a RA messages is received with valid
+ *     PIO option fields and an IPv6 address will be added to the interface
+ *     for autoconfiguration. The parameter dev_addr_generated reports about
+ *     if the address was based on dev->dev_addr or not. This can be used
+ *     to add a second address if link-layer operates with two link layer
+ *     addresses. E.g. 802.15.4 6LoWPAN.
+ */
+struct ndisc_ops {
+	int	(*is_useropt)(u8 nd_opt_type);
+	int	(*parse_options)(const struct net_device *dev,
+				 struct nd_opt_hdr *nd_opt,
+				 struct ndisc_options *ndopts);
+	void	(*update)(const struct net_device *dev, struct neighbour *n,
+			  u32 flags, u8 icmp6_type,
+			  const struct ndisc_options *ndopts);
+	int	(*opt_addr_space)(const struct net_device *dev, u8 icmp6_type,
+				  struct neighbour *neigh, u8 *ha_buf,
+				  u8 **ha);
+	void	(*fill_addr_option)(const struct net_device *dev,
+				    struct sk_buff *skb, u8 icmp6_type,
+				    const u8 *ha);
+	void	(*prefix_rcv_add_addr)(struct net *net, struct net_device *dev,
+				       const struct prefix_info *pinfo,
+				       struct inet6_dev *in6_dev,
+				       struct in6_addr *addr,
+				       int addr_type, u32 addr_flags,
+				       bool sllao, bool tokenized,
+				       __u32 valid_lft, u32 prefered_lft,
+				       bool dev_addr_generated);
+};
+
+#if IS_ENABLED(CONFIG_IPV6)
+static inline int ndisc_ops_is_useropt(const struct net_device *dev,
+				       u8 nd_opt_type)
+{
+	if (dev->ndisc_ops && dev->ndisc_ops->is_useropt)
+		return dev->ndisc_ops->is_useropt(nd_opt_type);
+	else
+		return 0;
+}
+
+static inline int ndisc_ops_parse_options(const struct net_device *dev,
+					  struct nd_opt_hdr *nd_opt,
+					  struct ndisc_options *ndopts)
+{
+	if (dev->ndisc_ops && dev->ndisc_ops->parse_options)
+		return dev->ndisc_ops->parse_options(dev, nd_opt, ndopts);
+	else
+		return 0;
+}
+
+static inline void ndisc_ops_update(const struct net_device *dev,
+					  struct neighbour *n, u32 flags,
+					  u8 icmp6_type,
+					  const struct ndisc_options *ndopts)
+{
+	if (dev->ndisc_ops && dev->ndisc_ops->update)
+		dev->ndisc_ops->update(dev, n, flags, icmp6_type, ndopts);
+}
+
+static inline int ndisc_ops_opt_addr_space(const struct net_device *dev,
+					   u8 icmp6_type)
+{
+	if (dev->ndisc_ops && dev->ndisc_ops->opt_addr_space &&
+	    icmp6_type != NDISC_REDIRECT)
+		return dev->ndisc_ops->opt_addr_space(dev, icmp6_type, NULL,
+						      NULL, NULL);
+	else
+		return 0;
+}
+
+static inline int ndisc_ops_redirect_opt_addr_space(const struct net_device *dev,
+						    struct neighbour *neigh,
+						    u8 *ha_buf, u8 **ha)
+{
+	if (dev->ndisc_ops && dev->ndisc_ops->opt_addr_space)
+		return dev->ndisc_ops->opt_addr_space(dev, NDISC_REDIRECT,
+						      neigh, ha_buf, ha);
+	else
+		return 0;
+}
+
+static inline void ndisc_ops_fill_addr_option(const struct net_device *dev,
+					      struct sk_buff *skb,
+					      u8 icmp6_type)
+{
+	if (dev->ndisc_ops && dev->ndisc_ops->fill_addr_option &&
+	    icmp6_type != NDISC_REDIRECT)
+		dev->ndisc_ops->fill_addr_option(dev, skb, icmp6_type, NULL);
+}
+
+static inline void ndisc_ops_fill_redirect_addr_option(const struct net_device *dev,
+						       struct sk_buff *skb,
+						       const u8 *ha)
+{
+	if (dev->ndisc_ops && dev->ndisc_ops->fill_addr_option)
+		dev->ndisc_ops->fill_addr_option(dev, skb, NDISC_REDIRECT, ha);
+}
+
+static inline void ndisc_ops_prefix_rcv_add_addr(struct net *net,
+						 struct net_device *dev,
+						 const struct prefix_info *pinfo,
+						 struct inet6_dev *in6_dev,
+						 struct in6_addr *addr,
+						 int addr_type, u32 addr_flags,
+						 bool sllao, bool tokenized,
+						 __u32 valid_lft,
+						 u32 prefered_lft,
+						 bool dev_addr_generated)
+{
+	if (dev->ndisc_ops && dev->ndisc_ops->prefix_rcv_add_addr)
+		dev->ndisc_ops->prefix_rcv_add_addr(net, dev, pinfo, in6_dev,
+						    addr, addr_type,
+						    addr_flags, sllao,
+						    tokenized, valid_lft,
+						    prefered_lft,
+						    dev_addr_generated);
+}
+#endif
+
 /*
  * Return the padding between the option length and the start of the
  * link addr.  Currently only IP-over-InfiniBand needs this, although
@@ -127,23 +319,48 @@ static inline int ndisc_addr_option_pad(unsigned short type)
 	}
 }
 
-static inline int ndisc_opt_addr_space(struct net_device *dev)
+static inline int __ndisc_opt_addr_space(unsigned char addr_len, int pad)
 {
-	return NDISC_OPT_SPACE(dev->addr_len +
-			       ndisc_addr_option_pad(dev->type));
+	return NDISC_OPT_SPACE(addr_len + pad);
 }
 
-static inline u8 *ndisc_opt_addr_data(struct nd_opt_hdr *p,
-				      struct net_device *dev)
+#if IS_ENABLED(CONFIG_IPV6)
+static inline int ndisc_opt_addr_space(struct net_device *dev, u8 icmp6_type)
+{
+	return __ndisc_opt_addr_space(dev->addr_len,
+				      ndisc_addr_option_pad(dev->type)) +
+		ndisc_ops_opt_addr_space(dev, icmp6_type);
+}
+
+static inline int ndisc_redirect_opt_addr_space(struct net_device *dev,
+						struct neighbour *neigh,
+						u8 *ops_data_buf,
+						u8 **ops_data)
+{
+	return __ndisc_opt_addr_space(dev->addr_len,
+				      ndisc_addr_option_pad(dev->type)) +
+		ndisc_ops_redirect_opt_addr_space(dev, neigh, ops_data_buf,
+						  ops_data);
+}
+#endif
+
+static inline u8 *__ndisc_opt_addr_data(struct nd_opt_hdr *p,
+					unsigned char addr_len, int prepad)
 {
 	u8 *lladdr = (u8 *)(p + 1);
 	int lladdrlen = p->nd_opt_len << 3;
-	int prepad = ndisc_addr_option_pad(dev->type);
-	if (lladdrlen != ndisc_opt_addr_space(dev))
+	if (lladdrlen != __ndisc_opt_addr_space(addr_len, prepad))
 		return NULL;
 	return lladdr + prepad;
 }
 
+static inline u8 *ndisc_opt_addr_data(struct nd_opt_hdr *p,
+				      struct net_device *dev)
+{
+	return __ndisc_opt_addr_data(p, dev->addr_len,
+				     ndisc_addr_option_pad(dev->type));
+}
+
 static inline u32 ndisc_hashfn(const void *pkey, const struct net_device *dev, __u32 *hash_rnd)
 {
 	const u32 *p32 = pkey;
@@ -194,6 +411,9 @@ void ndisc_send_redirect(struct sk_buff *skb, const struct in6_addr *target);
 int ndisc_mc_map(const struct in6_addr *addr, char *buf, struct net_device *dev,
 		 int dir);
 
+void ndisc_update(const struct net_device *dev, struct neighbour *neigh,
+		  const u8 *lladdr, u8 new, u32 flags, u8 icmp6_type,
+		  struct ndisc_options *ndopts);
 
 /*
  *	IGMP