[PATCH net-next 2/3] net/smc: add ipv6 support to CLC layer

[Ursula Braun <ubraun@linux.vnet.ibm.com>]

From: Karsten Graul <kgraul@linux.vnet.ibm.com>

The CLC layer is updated to support ipv6 proposal messages from peers and
to match incoming proposal messages against the ipv6 addresses of the net
device. struct smc_clc_ipv6_prefix is updated to provide the space for an
ipv6 address (struct was not used before). SMC_CLC_MAX_LEN is updated to
include the size of the proposal prefix. Existing code in net is not
affected, the previous SMC_CLC_MAX_LEN value is large enough to hold ipv4
proposal messages.

Signed-off-by: Karsten Graul <kgraul@linux.vnet.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
---
 net/smc/smc_clc.c | 109 +++++++++++++++++++++++++++++++++++++++++++++++-------
 net/smc/smc_clc.h |  13 +++++--
 2 files changed, 105 insertions(+), 17 deletions(-)

diff --git a/net/smc/smc_clc.c b/net/smc/smc_clc.c
index dc3a2235978d..64fbc3230e6c 100644
--- a/net/smc/smc_clc.c
+++ b/net/smc/smc_clc.c
@@ -5,7 +5,7 @@
  *  CLC (connection layer control) handshake over initial TCP socket to
  *  prepare for RDMA traffic
  *
- *  Copyright IBM Corp. 2016
+ *  Copyright IBM Corp. 2016, 2018
  *
  *  Author(s):  Ursula Braun <ubraun@linux.vnet.ibm.com>
  */
@@ -15,6 +15,7 @@
 #include <linux/if_ether.h>
 #include <linux/sched/signal.h>
 
+#include <net/addrconf.h>
 #include <net/sock.h>
 #include <net/tcp.h>
 
@@ -93,12 +94,44 @@ static int smc_clc_prfx_set4_rcu(struct dst_entry *dst, __be32 ipv4,
 	return -ENOENT;
 }
 
+/* fill CLC proposal msg with ipv6 prefixes from device */
+static int smc_clc_prfx_set6_rcu(struct dst_entry *dst,
+				 struct smc_clc_msg_proposal_prefix *prop,
+				 struct smc_clc_ipv6_prefix *ipv6_prfx)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	struct inet6_dev *in6_dev = __in6_dev_get(dst->dev);
+	struct inet6_ifaddr *ifa;
+	int cnt = 0;
+
+	if (!in6_dev)
+		return -ENODEV;
+	/* use a maximum of 8 IPv6 prefixes from device */
+	list_for_each_entry(ifa, &in6_dev->addr_list, if_list) {
+		if (ipv6_addr_type(&ifa->addr) & IPV6_ADDR_LINKLOCAL)
+			continue;
+		ipv6_addr_prefix(&ipv6_prfx[cnt].prefix,
+				 &ifa->addr, ifa->prefix_len);
+		ipv6_prfx[cnt].prefix_len = ifa->prefix_len;
+		cnt++;
+		if (cnt == SMC_CLC_MAX_V6_PREFIX)
+			break;
+	}
+	prop->ipv6_prefixes_cnt = cnt;
+	if (cnt)
+		return 0;
+#endif
+	return -ENOENT;
+}
+
 /* retrieve and set prefixes in CLC proposal msg */
 static int smc_clc_prfx_set(struct socket *clcsock,
-			    struct smc_clc_msg_proposal_prefix *prop)
+			    struct smc_clc_msg_proposal_prefix *prop,
+			    struct smc_clc_ipv6_prefix *ipv6_prfx)
 {
 	struct dst_entry *dst = sk_dst_get(clcsock->sk);
 	struct sockaddr_storage addrs;
+	struct sockaddr_in6 *addr6;
 	struct sockaddr_in *addr;
 	int rc = -ENOENT;
 
@@ -114,11 +147,19 @@ static int smc_clc_prfx_set(struct socket *clcsock,
 	/* get address to which the internal TCP socket is bound */
 	kernel_getsockname(clcsock, (struct sockaddr *)&addrs);
 	/* analyze IP specific data of net_device belonging to TCP socket */
+	addr6 = (struct sockaddr_in6 *)&addrs;
 	rcu_read_lock();
 	if (addrs.ss_family == PF_INET) {
 		/* IPv4 */
 		addr = (struct sockaddr_in *)&addrs;
 		rc = smc_clc_prfx_set4_rcu(dst, addr->sin_addr.s_addr, prop);
+	} else if (ipv6_addr_v4mapped(&addr6->sin6_addr)) {
+		/* mapped IPv4 address - peer is IPv4 only */
+		rc = smc_clc_prfx_set4_rcu(dst, addr6->sin6_addr.s6_addr32[3],
+					   prop);
+	} else {
+		/* IPv6 */
+		rc = smc_clc_prfx_set6_rcu(dst, prop, ipv6_prfx);
 	}
 	rcu_read_unlock();
 out_rel:
@@ -144,12 +185,41 @@ static int smc_clc_prfx_match4_rcu(struct net_device *dev,
 	return -ENOENT;
 }
 
+/* match ipv6 addrs of dev against addrs in CLC proposal */
+static int smc_clc_prfx_match6_rcu(struct net_device *dev,
+				   struct smc_clc_msg_proposal_prefix *prop)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+	struct inet6_dev *in6_dev = __in6_dev_get(dev);
+	struct smc_clc_ipv6_prefix *ipv6_prfx;
+	struct inet6_ifaddr *ifa;
+	int i, max;
+
+	if (!in6_dev)
+		return -ENODEV;
+	/* ipv6 prefix list starts behind smc_clc_msg_proposal_prefix */
+	ipv6_prfx = (struct smc_clc_ipv6_prefix *)((u8 *)prop + sizeof(*prop));
+	max = min_t(u8, prop->ipv6_prefixes_cnt, SMC_CLC_MAX_V6_PREFIX);
+	list_for_each_entry(ifa, &in6_dev->addr_list, if_list) {
+		if (ipv6_addr_type(&ifa->addr) & IPV6_ADDR_LINKLOCAL)
+			continue;
+		for (i = 0; i < max; i++) {
+			if (ifa->prefix_len == ipv6_prfx[i].prefix_len &&
+			    ipv6_prefix_equal(&ifa->addr, &ipv6_prfx[i].prefix,
+					      ifa->prefix_len))
+				return 0;
+		}
+	}
+#endif
+	return -ENOENT;
+}
+
 /* check if proposed prefixes match one of our device prefixes */
 int smc_clc_prfx_match(struct socket *clcsock,
 		       struct smc_clc_msg_proposal_prefix *prop)
 {
 	struct dst_entry *dst = sk_dst_get(clcsock->sk);
-	int rc = -ENOENT;
+	int rc;
 
 	if (!dst) {
 		rc = -ENOTCONN;
@@ -162,6 +232,8 @@ int smc_clc_prfx_match(struct socket *clcsock,
 	rcu_read_lock();
 	if (!prop->ipv6_prefixes_cnt)
 		rc = smc_clc_prfx_match4_rcu(dst->dev, prop);
+	else
+		rc = smc_clc_prfx_match6_rcu(dst->dev, prop);
 	rcu_read_unlock();
 out_rel:
 	dst_release(dst);
@@ -288,21 +360,24 @@ int smc_clc_send_proposal(struct smc_sock *smc,
 			  struct smc_ib_device *smcibdev,
 			  u8 ibport)
 {
+	struct smc_clc_ipv6_prefix ipv6_prfx[SMC_CLC_MAX_V6_PREFIX];
 	struct smc_clc_msg_proposal_prefix pclc_prfx;
 	struct smc_clc_msg_proposal pclc;
 	struct smc_clc_msg_trail trl;
+	int len, i, plen, rc;
 	int reason_code = 0;
-	struct kvec vec[3];
+	struct kvec vec[4];
 	struct msghdr msg;
-	int len, plen, rc;
 
 	/* retrieve ip prefixes for CLC proposal msg */
-	rc = smc_clc_prfx_set(smc->clcsock, &pclc_prfx);
+	rc = smc_clc_prfx_set(smc->clcsock, &pclc_prfx, ipv6_prfx);
 	if (rc)
 		return SMC_CLC_DECL_CNFERR; /* configuration error */
 
 	/* send SMC Proposal CLC message */
-	plen = sizeof(pclc) + sizeof(pclc_prfx) + sizeof(trl);
+	plen = sizeof(pclc) + sizeof(pclc_prfx) +
+	       (pclc_prfx.ipv6_prefixes_cnt * sizeof(ipv6_prfx[0])) +
+	       sizeof(trl);
 	memset(&pclc, 0, sizeof(pclc));
 	memcpy(pclc.hdr.eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER));
 	pclc.hdr.type = SMC_CLC_PROPOSAL;
@@ -315,14 +390,20 @@ int smc_clc_send_proposal(struct smc_sock *smc,
 
 	memcpy(trl.eyecatcher, SMC_EYECATCHER, sizeof(SMC_EYECATCHER));
 	memset(&msg, 0, sizeof(msg));
-	vec[0].iov_base = &pclc;
-	vec[0].iov_len = sizeof(pclc);
-	vec[1].iov_base = &pclc_prfx;
-	vec[1].iov_len = sizeof(pclc_prfx);
-	vec[2].iov_base = &trl;
-	vec[2].iov_len = sizeof(trl);
+	i = 0;
+	vec[i].iov_base = &pclc;
+	vec[i++].iov_len = sizeof(pclc);
+	vec[i].iov_base = &pclc_prfx;
+	vec[i++].iov_len = sizeof(pclc_prfx);
+	if (pclc_prfx.ipv6_prefixes_cnt > 0) {
+		vec[i].iov_base = &ipv6_prfx[0];
+		vec[i++].iov_len = pclc_prfx.ipv6_prefixes_cnt *
+				   sizeof(ipv6_prfx[0]);
+	}
+	vec[i].iov_base = &trl;
+	vec[i++].iov_len = sizeof(trl);
 	/* due to the few bytes needed for clc-handshake this cannot block */
-	len = kernel_sendmsg(smc->clcsock, &msg, vec, 3, plen);
+	len = kernel_sendmsg(smc->clcsock, &msg, vec, i, plen);
 	if (len < sizeof(pclc)) {
 		if (len >= 0) {
 			reason_code = -ENETUNREACH;
diff --git a/net/smc/smc_clc.h b/net/smc/smc_clc.h
index 5ddb0d22eb8a..63bf1dc2c1f9 100644
--- a/net/smc/smc_clc.h
+++ b/net/smc/smc_clc.h
@@ -60,10 +60,15 @@ struct smc_clc_msg_local {	/* header2 of clc messages */
 	u8 mac[6];		/* mac of ib_device port */
 };
 
+#define SMC_CLC_MAX_V6_PREFIX	8
+
+/* Struct would be 4 byte aligned, but it is used in an array that is sent
+ * to peers and must conform to RFC7609, hence we need to use packed here.
+ */
 struct smc_clc_ipv6_prefix {
-	u8 prefix[4];
+	struct in6_addr prefix;
 	u8 prefix_len;
-} __packed;
+} __packed;			/* format defined in RFC7609 */
 
 struct smc_clc_msg_proposal_prefix {	/* prefix part of clc proposal message*/
 	__be32 outgoing_subnet;	/* subnet mask */
@@ -79,9 +84,11 @@ struct smc_clc_msg_proposal {	/* clc proposal message sent by Linux */
 } __aligned(4);
 
 #define SMC_CLC_PROPOSAL_MAX_OFFSET	0x28
-#define SMC_CLC_PROPOSAL_MAX_PREFIX	(8 * sizeof(struct smc_clc_ipv6_prefix))
+#define SMC_CLC_PROPOSAL_MAX_PREFIX	(SMC_CLC_MAX_V6_PREFIX * \
+					 sizeof(struct smc_clc_ipv6_prefix))
 #define SMC_CLC_MAX_LEN		(sizeof(struct smc_clc_msg_proposal) + \
 				 SMC_CLC_PROPOSAL_MAX_OFFSET + \
+				 sizeof(struct smc_clc_msg_proposal_prefix) + \
 				 SMC_CLC_PROPOSAL_MAX_PREFIX + \
 				 sizeof(struct smc_clc_msg_trail))
 
-- 
2.13.5