xfrm: Notify changes in UDP encapsulation via netlink

Add new_mapping() implementation to the netlink xfrm_mgr to notify
address/port changes detected in UDP encapsulated ESP packets.

Signed-off-by: Martin Willi <martin@strongswan.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 66 insertions, 0 deletions

diff --git a/include/linux/xfrm.h b/include/linux/xfrm.h
index 4bc1e6b86cb2..52f3abd453a1 100644
--- a/include/linux/xfrm.h
+++ b/include/linux/xfrm.h
@@ -199,6 +199,9 @@ enum {
 #define XFRM_MSG_NEWSPDINFO XFRM_MSG_NEWSPDINFO
         XFRM_MSG_GETSPDINFO,
 #define XFRM_MSG_GETSPDINFO XFRM_MSG_GETSPDINFO
+
+        XFRM_MSG_MAPPING,
+#define XFRM_MSG_MAPPING XFRM_MSG_MAPPING
         __XFRM_MSG_MAX
 };
 #define XFRM_MSG_MAX (__XFRM_MSG_MAX - 1)
@@ -438,6 +441,15 @@ struct xfrm_user_migrate {
         __u16                           new_family;
 };
 
+struct xfrm_user_mapping {
+        struct xfrm_usersa_id           id;
+        __u32                           reqid;
+        xfrm_address_t                  old_saddr;
+        xfrm_address_t                  new_saddr;
+        __be16                          old_sport;
+        __be16                          new_sport;
+};
+
 #ifndef __KERNEL__
 /* backwards compatibility for userspace */
 #define XFRMGRP_ACQUIRE         1
@@ -464,6 +476,8 @@ enum xfrm_nlgroups {
 #define XFRMNLGRP_REPORT        XFRMNLGRP_REPORT
         XFRMNLGRP_MIGRATE,
 #define XFRMNLGRP_MIGRATE       XFRMNLGRP_MIGRATE
+        XFRMNLGRP_MAPPING,
+#define XFRMNLGRP_MAPPING       XFRMNLGRP_MAPPING
         __XFRMNLGRP_MAX
 };
 #define XFRMNLGRP_MAX   (__XFRMNLGRP_MAX - 1)
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 4a8a1abb59ee..76cf56d5d834 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -2503,6 +2503,57 @@ static int xfrm_send_report(u8 proto, struct xfrm_selector *sel,
         return nlmsg_multicast(xfrm_nl, skb, 0, XFRMNLGRP_REPORT, GFP_ATOMIC);
 }
 
+static inline size_t xfrm_mapping_msgsize(void)
+{
+        return NLMSG_ALIGN(sizeof(struct xfrm_user_mapping));
+}
+
+static int build_mapping(struct sk_buff *skb, struct xfrm_state *x,
+                         xfrm_address_t *new_saddr, __be16 new_sport)
+{
+        struct xfrm_user_mapping *um;
+        struct nlmsghdr *nlh;
+
+        nlh = nlmsg_put(skb, 0, 0, XFRM_MSG_MAPPING, sizeof(*um), 0);
+        if (nlh == NULL)
+                return -EMSGSIZE;
+
+        um = nlmsg_data(nlh);
+
+        memcpy(&um->id.daddr, &x->id.daddr, sizeof(um->id.daddr));
+        um->id.spi = x->id.spi;
+        um->id.family = x->props.family;
+        um->id.proto = x->id.proto;
+        memcpy(&um->new_saddr, new_saddr, sizeof(um->new_saddr));
+        memcpy(&um->old_saddr, &x->props.saddr, sizeof(um->old_saddr));
+        um->new_sport = new_sport;
+        um->old_sport = x->encap->encap_sport;
+        um->reqid = x->props.reqid;
+
+        return nlmsg_end(skb, nlh);
+}
+
+static int xfrm_send_mapping(struct xfrm_state *x, xfrm_address_t *ipaddr,
+                             __be16 sport)
+{
+        struct sk_buff *skb;
+
+        if (x->id.proto != IPPROTO_ESP)
+                return -EINVAL;
+
+        if (!x->encap)
+                return -EINVAL;
+
+        skb = nlmsg_new(xfrm_mapping_msgsize(), GFP_ATOMIC);
+        if (skb == NULL)
+                return -ENOMEM;
+
+        if (build_mapping(skb, x, ipaddr, sport) < 0)
+                BUG();
+
+        return nlmsg_multicast(xfrm_nl, skb, 0, XFRMNLGRP_MAPPING, GFP_ATOMIC);
+}
+
 static struct xfrm_mgr netlink_mgr = {
         .id             = "netlink",
         .notify         = xfrm_send_state_notify,
@@ -2511,6 +2562,7 @@ static struct xfrm_mgr netlink_mgr = {
         .notify_policy  = xfrm_send_policy_notify,
         .report         = xfrm_send_report,
         .migrate        = xfrm_send_migrate,
+        .new_mapping    = xfrm_send_mapping,
 };
 
 static int __init xfrm_user_init(void)