From: Peter Krystad <peter.krys...@linux.intel.com>

Add handling for sending and receiving the ADD_ADDR, ADD_ADDR6,
and RM_ADDR suboptions.

Signed-off-by: Peter Krystad <peter.krys...@linux.intel.com>
---
 include/linux/tcp.h  |   2 +
 include/net/mptcp.h  |   7 +++
 net/mptcp/options.c  | 115 +++++++++++++++++++++++++++++++++++++++----
 net/mptcp/protocol.h |  16 +++++-
 4 files changed, 130 insertions(+), 10 deletions(-)

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 31e546fe9643..b3289e69cac1 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -118,6 +118,7 @@ struct tcp_options_received {
                        ack64:1,
                        __unused:2;
                u8      add_addr : 1,
+                       rm_addr : 1,
                        family : 4;
                u8      addr_id;
                union {
@@ -139,6 +140,7 @@ static inline void tcp_clear_options(struct 
tcp_options_received *rx_opt)
 #endif
 #if IS_ENABLED(CONFIG_MPTCP)
        rx_opt->mptcp.mp_capable = rx_opt->mptcp.mp_join = 0;
+       rx_opt->mptcp.add_addr = rx_opt->mptcp.rm_addr = 0;
        rx_opt->mptcp.dss = 0;
 #endif
 }
diff --git a/include/net/mptcp.h b/include/net/mptcp.h
index 21438bcacb14..f4a9962ea85f 100644
--- a/include/net/mptcp.h
+++ b/include/net/mptcp.h
@@ -29,6 +29,13 @@ struct mptcp_out_options {
        u16 suboptions;
        u64 sndr_key;
        u64 rcvr_key;
+       union {
+               struct in_addr addr;
+#if IS_ENABLED(CONFIG_IPV6)
+               struct in6_addr addr6;
+#endif
+       };
+       u8 addr_id;
        struct mptcp_ext ext_copy;
 #endif
 };
diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 2981c0daa12c..6fd2c8b5001c 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -173,12 +173,51 @@ void mptcp_parse_option(const unsigned char *ptr, int 
opsize,
         * 4 or 16 bytes of address (depending on ip version)
         * 0 or 2 bytes of port (depending on length)
         */
+       case MPTCPOPT_ADD_ADDR:
+               if (opsize != TCPOLEN_MPTCP_ADD_ADDR &&
+                   opsize != TCPOLEN_MPTCP_ADD_ADDR6)
+                       break;
+               mp_opt->family = *ptr++ & MPTCP_ADDR_FAMILY_MASK;
+               if (mp_opt->family != MPTCP_ADDR_IPVERSION_4 &&
+                   mp_opt->family != MPTCP_ADDR_IPVERSION_6)
+                       break;
+
+               if (mp_opt->family == MPTCP_ADDR_IPVERSION_4 &&
+                   opsize != TCPOLEN_MPTCP_ADD_ADDR)
+                       break;
+#if IS_ENABLED(CONFIG_IPV6)
+               if (mp_opt->family == MPTCP_ADDR_IPVERSION_6 &&
+                   opsize != TCPOLEN_MPTCP_ADD_ADDR6)
+                       break;
+#endif
+               mp_opt->addr_id = *ptr++;
+               if (mp_opt->family == MPTCP_ADDR_IPVERSION_4) {
+                       mp_opt->add_addr = 1;
+                       memcpy((u8 *)&mp_opt->addr.s_addr, (u8 *)ptr, 4);
+                       pr_debug("ADD_ADDR: addr=%x, id=%d",
+                                mp_opt->addr.s_addr, mp_opt->addr_id);
+#if IS_ENABLED(CONFIG_IPV6)
+               } else {
+                       mp_opt->add_addr = 1;
+                       memcpy(mp_opt->addr6.s6_addr, (u8 *)ptr, 16);
+                       pr_debug("ADD_ADDR: addr6=, id=%d", mp_opt->addr_id);
+#endif
+               }
+               break;
 
        /* MPTCPOPT_RM_ADDR
         * 0: 4MSB=subtype, 0000
         * 1: Address ID
         * Additional bytes: More address IDs (depending on length)
         */
+       case MPTCPOPT_RM_ADDR:
+               if (opsize != TCPOLEN_MPTCP_RM_ADDR)
+                       break;
+
+               mp_opt->rm_addr = 1;
+               mp_opt->addr_id = *ptr++;
+               pr_debug("RM_ADDR: id=%d", mp_opt->addr_id);
+               break;
 
        /* MPTCPOPT_MP_PRIO
         * 0: 4MSB=subtype, 000, 1LSB=Backup
@@ -352,27 +391,65 @@ static bool mptcp_established_options_dss(struct sock 
*sk, struct sk_buff *skb,
        return true;
 }
 
+static bool mptcp_established_options_addr(struct sock *sk,
+                                          unsigned int *size,
+                                          unsigned int remaining,
+                                          struct mptcp_out_options *opts)
+{
+       struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
+       struct mptcp_sock *msk = mptcp_sk(subflow->conn);
+       struct sockaddr_storage saddr;
+       u8 id;
+
+       if (!msk)
+               return false;
+
+       if (!msk->pm.fully_established || !msk->addr_signal)
+               return false;
+
+       if (pm_addr_signal(msk, &id, &saddr))
+               return false;
+
+       if (saddr.ss_family == AF_INET && remaining < TCPOLEN_MPTCP_ADD_ADDR)
+               return false;
+
+       opts->suboptions |= OPTION_MPTCP_ADD_ADDR;
+       opts->addr_id = id;
+       opts->addr.s_addr = ((struct sockaddr_in *)&saddr)->sin_addr.s_addr;
+       *size = TCPOLEN_MPTCP_ADD_ADDR;
+
+       msk->addr_signal = 0;
+
+       return true;
+}
+
 bool mptcp_established_options(struct sock *sk, struct sk_buff *skb,
                               unsigned int *size, unsigned int remaining,
                               struct mptcp_out_options *opts)
 {
        unsigned int opt_size = 0;
+       bool ret = false;
 
        if (!mptcp_subflow_ctx(sk)->mp_capable)
                return false;
 
+       opts->suboptions = 0;
        if (mptcp_established_options_mp(sk, &opt_size, remaining, opts)) {
                *size += opt_size;
                remaining -= opt_size;
-               return true;
+               ret = true;
        } else if (mptcp_established_options_dss(sk, skb, &opt_size, remaining,
-                                              opts)) {
+                                                opts)) {
                *size += opt_size;
                remaining -= opt_size;
-               return true;
+               ret = true;
        }
-
-       return false;
+       if (mptcp_established_options_addr(sk, &opt_size, remaining, opts)) {
+               *size += opt_size;
+               remaining -= opt_size;
+               ret = true;
+       }
+       return ret;
 }
 
 bool mptcp_synack_options(const struct request_sock *req, unsigned int *size,
@@ -459,10 +536,8 @@ void mptcp_write_options(__be32 *ptr, struct 
mptcp_out_options *opts)
                else
                        len = TCPOLEN_MPTCP_MPC_ACK;
 
-               *ptr++ = htonl((TCPOPT_MPTCP << 24) | (len << 16) |
-                              (MPTCPOPT_MP_CAPABLE << 12) |
-                              ((MPTCP_VERSION_MASK & 0) << 8) |
-                              MPTCP_CAP_HMAC_SHA1);
+               *ptr++ = mptcp_option(MPTCPOPT_MP_CAPABLE, len, 0,
+                                     MPTCP_CAP_HMAC_SHA1);
                put_unaligned_be64(opts->sndr_key, ptr);
                ptr += 2;
                if ((OPTION_MPTCP_MPC_SYNACK |
@@ -472,6 +547,28 @@ void mptcp_write_options(__be32 *ptr, struct 
mptcp_out_options *opts)
                }
        }
 
+       if (OPTION_MPTCP_ADD_ADDR & opts->suboptions) {
+               *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR, TCPOLEN_MPTCP_ADD_ADDR,
+                                     MPTCP_ADDR_IPVERSION_4, opts->addr_id);
+               memcpy((u8 *)ptr, (u8 *)&opts->addr.s_addr, 4);
+               ptr += 1;
+       }
+
+#if IS_ENABLED(CONFIG_IPV6)
+       if (OPTION_MPTCP_ADD_ADDR6 & opts->suboptions) {
+               *ptr++ = mptcp_option(MPTCPOPT_ADD_ADDR,
+                                     TCPOLEN_MPTCP_ADD_ADDR6,
+                                     MPTCP_ADDR_IPVERSION_6, opts->addr_id);
+               memcpy((u8 *)ptr, opts->addr6.s6_addr, 16);
+               ptr += 4;
+       }
+#endif
+
+       if (OPTION_MPTCP_RM_ADDR & opts->suboptions) {
+               *ptr++ = mptcp_option(MPTCPOPT_RM_ADDR, TCPOLEN_MPTCP_RM_ADDR,
+                                     0, opts->addr_id);
+       }
+
        if (opts->ext_copy.use_ack || opts->ext_copy.use_map) {
                struct mptcp_ext *mpext = &opts->ext_copy;
                u8 len = TCPOLEN_MPTCP_DSS_BASE;
diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index 599c380145e3..fd21ed6c03b7 100644
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -8,13 +8,16 @@
 #define __MPTCP_PROTOCOL_H
 
 #include <linux/random.h>
-#include <linux/tcp.h>
+#include <net/tcp.h>
 #include <net/inet_connection_sock.h>
 
 /* MPTCP option bits */
 #define OPTION_MPTCP_MPC_SYN   BIT(0)
 #define OPTION_MPTCP_MPC_SYNACK        BIT(1)
 #define OPTION_MPTCP_MPC_ACK   BIT(2)
+#define OPTION_MPTCP_ADD_ADDR  BIT(6)
+#define OPTION_MPTCP_ADD_ADDR6 BIT(7)
+#define OPTION_MPTCP_RM_ADDR   BIT(8)
 
 /* MPTCP option subtypes */
 #define MPTCPOPT_MP_CAPABLE    0
@@ -36,6 +39,9 @@
 #define TCPOLEN_MPTCP_DSS_MAP32                10
 #define TCPOLEN_MPTCP_DSS_MAP64                14
 #define TCPOLEN_MPTCP_DSS_CHECKSUM     2
+#define TCPOLEN_MPTCP_ADD_ADDR         8
+#define TCPOLEN_MPTCP_ADD_ADDR6                20
+#define TCPOLEN_MPTCP_RM_ADDR          4
 
 /* MPTCP MP_CAPABLE flags */
 #define MPTCP_VERSION_MASK     (0x0F)
@@ -53,9 +59,16 @@
 #define MPTCP_DSS_FLAG_MASK    (0x1F)
 
 /* MPTCP ADD_ADDR flags */
+#define MPTCP_ADDR_FAMILY_MASK (0x0F)
 #define MPTCP_ADDR_IPVERSION_4 4
 #define MPTCP_ADDR_IPVERSION_6 6
 
+static inline __be32 mptcp_option(u8 subopt, u8 len, u8 nib, u8 field)
+{
+       return htonl((TCPOPT_MPTCP << 24) | (len << 16) | (subopt << 12) |
+                    ((nib & 0xF) << 8) | field);
+}
+
 struct mptcp_pm_data {
        u8      local_valid;
        u8      local_id;
@@ -96,6 +109,7 @@ struct mptcp_sock {
        struct list_head conn_list;
        struct socket   *subflow; /* outgoing connect/listener/!mp_capable */
        struct mptcp_pm_data    pm;
+       u8              addr_signal;
 };
 
 #define mptcp_for_each_subflow(__msk, __subflow)                       \
-- 
2.23.0

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