Add a new netlink method to migrate a single xfrm_state.
Unlike the existing migration mechanism (SA + policy), this
supports migrating only the SA and allows changing the reqid.

The SA is looked up via xfrm_usersa_id, which uniquely
identifies it, so old_saddr is not needed. old_daddr is carried in
xfrm_usersa_id.daddr.

The reqid is invariant in the old migration.

Signed-off-by: Antony Antony <antony.antony@secunet.com>
---
v6->v7: - add flags field to xfrm_user_migrate_state (based on Sabrina's feedback)
  - add XFRM_MIGRATE_STATE_NO_OFFLOAD (bit 0): suppresses offload
  - omit-to-inherit; mutually exclusive with XFRMA_OFFLOAD_DEV
  - zero-initialize struct xfrm_migrate m[XFRM_MAX_DEPTH]
  - add struct xfrm_selector new_sel to xfrm_user_migrate_state
  - add XFRM_MIGRATE_STATE_UPDATE_SEL: derive new selector
    from SA addresses when old selector is a single-host match
v5->v6: - (Feedback from Sabrina's review)
  - reqid change: use xfrm_state_add, not xfrm_state_insert
  - encap and xuo: use nla_data() directly, no kmemdup needed
  - notification failure is non-fatal: set extack warning, return 0
  - drop state direction, x->dir, check, not required
  - reverse xmas tree local variable ordering
  - use NL_SET_ERR_MSG_WEAK for clone failure message
  - fix implicit padding in xfrm_user_migrate_state uapi struct
  - support XFRMA_SET_MARK/XFRMA_SET_MARK_MASK in XFRM_MSG_MIGRATE_STATE
v4->v5: - set portid, seq in XFRM_MSG_MIGRATE_STATE netlink notification
  - rename error label to out for clarity
  - add locking and synchronize after cloning
  - change some if(x) to if(!x) for clarity
  - call __xfrm_state_delete() inside the lock
  - return error from xfrm_send_migrate_state() instead of always returning 0
v3->v4: preserve reqid invariant for each state migrated
v2->v3: free the skb on the error path
v1->v2: merged next patch here to fix use uninitialized value
  - removed unnecessary inline
  - added const when possible
---
 include/net/xfrm.h          |  16 ++-
 include/uapi/linux/xfrm.h   |  21 ++++
 net/xfrm/xfrm_device.c      |   2 +-
 net/xfrm/xfrm_policy.c      |  19 +++
 net/xfrm/xfrm_state.c       |  29 +++--
 net/xfrm/xfrm_user.c        | 287 +++++++++++++++++++++++++++++++++++++++++++-
 security/selinux/nlmsgtab.c |   3 +-
 7 files changed, 363 insertions(+), 14 deletions(-)

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 4b29ab92c2a7..e33e524cd909 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -684,12 +684,20 @@ struct xfrm_migrate {
 	xfrm_address_t		new_saddr;
 	struct xfrm_encap_tmpl *encap;
 	struct xfrm_user_offload *xuo;
+	struct xfrm_mark        old_mark;
+	struct xfrm_mark       *new_mark;
+	struct xfrm_mark        smark;
 	u8			proto;
 	u8			mode;
-	u16			reserved;
+	u16			msg_type; /* XFRM_MSG_MIGRATE or XFRM_MSG_MIGRATE_STATE */
+	u32			flags;
 	u32			old_reqid;
+	u32			new_reqid;
+	u32			nat_keepalive_interval;
+	u32			mapping_maxage;
 	u16			old_family;
 	u16			new_family;
+	const struct xfrm_selector *new_sel;
 };
 
 #define XFRM_KM_TIMEOUT                30
@@ -2104,7 +2112,7 @@ void xfrm_dev_resume(struct sk_buff *skb);
 void xfrm_dev_backlog(struct softnet_data *sd);
 struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t features, bool *again);
 int xfrm_dev_state_add(struct net *net, struct xfrm_state *x,
-		       struct xfrm_user_offload *xuo,
+		       const struct xfrm_user_offload *xuo,
 		       struct netlink_ext_ack *extack);
 int xfrm_dev_policy_add(struct net *net, struct xfrm_policy *xp,
 			struct xfrm_user_offload *xuo, u8 dir,
@@ -2175,7 +2183,9 @@ static inline struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_fea
 	return skb;
 }
 
-static inline int xfrm_dev_state_add(struct net *net, struct xfrm_state *x, struct xfrm_user_offload *xuo, struct netlink_ext_ack *extack)
+static inline int xfrm_dev_state_add(struct net *net, struct xfrm_state *x,
+				     const struct xfrm_user_offload *xuo,
+				     struct netlink_ext_ack *extack)
 {
 	return 0;
 }
diff --git a/include/uapi/linux/xfrm.h b/include/uapi/linux/xfrm.h
index a23495c0e0a1..34d8ad5c4818 100644
--- a/include/uapi/linux/xfrm.h
+++ b/include/uapi/linux/xfrm.h
@@ -227,6 +227,9 @@ enum {
 #define XFRM_MSG_SETDEFAULT XFRM_MSG_SETDEFAULT
 	XFRM_MSG_GETDEFAULT,
 #define XFRM_MSG_GETDEFAULT XFRM_MSG_GETDEFAULT
+
+	XFRM_MSG_MIGRATE_STATE,
+#define XFRM_MSG_MIGRATE_STATE XFRM_MSG_MIGRATE_STATE
 	__XFRM_MSG_MAX
 };
 #define XFRM_MSG_MAX (__XFRM_MSG_MAX - 1)
@@ -507,6 +510,24 @@ struct xfrm_user_migrate {
 	__u16				new_family;
 };
 
+struct xfrm_user_migrate_state {
+	struct xfrm_usersa_id id;
+	xfrm_address_t new_daddr;
+	xfrm_address_t new_saddr;
+	struct xfrm_mark old_mark;
+	struct xfrm_selector new_sel;
+	__u32 new_reqid;
+	__u32 flags;
+	__u16 new_family;
+	__u16 reserved;
+};
+
+/* Flags for xfrm_user_migrate_state.flags */
+enum xfrm_migrate_state_flags {
+	XFRM_MIGRATE_STATE_NO_OFFLOAD = 1, /* do not inherit offload from existing SA */
+	XFRM_MIGRATE_STATE_UPDATE_SEL = 2, /* update host-to-host selector from saddr and daddr */
+};
+
 struct xfrm_user_mapping {
 	struct xfrm_usersa_id		id;
 	__u32				reqid;
diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c
index 52ae0e034d29..9d4c1addb98f 100644
--- a/net/xfrm/xfrm_device.c
+++ b/net/xfrm/xfrm_device.c
@@ -229,7 +229,7 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur
 EXPORT_SYMBOL_GPL(validate_xmit_xfrm);
 
 int xfrm_dev_state_add(struct net *net, struct xfrm_state *x,
-		       struct xfrm_user_offload *xuo,
+		       const struct xfrm_user_offload *xuo,
 		       struct netlink_ext_ack *extack)
 {
 	int err;
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 0b5c7b51183a..3d6c778d8645 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -4635,6 +4635,22 @@ static int xfrm_migrate_check(const struct xfrm_migrate *m, int num_migrate,
 	return 0;
 }
 
+/*
+ * Fill migrate fields that are invariant in XFRM_MSG_MIGRATE: inherited
+ * from the existing SA unchanged. XFRM_MSG_MIGRATE_STATE can update these.
+ */
+static void xfrm_migrate_copy_old(struct xfrm_migrate *mp,
+				  const struct xfrm_state *x,
+				  struct xfrm_mark *new_mark_buf)
+{
+	mp->smark                  = x->props.smark;
+	mp->new_reqid              = x->props.reqid;
+	mp->nat_keepalive_interval = x->nat_keepalive_interval;
+	mp->mapping_maxage         = x->mapping_maxage;
+	*new_mark_buf              = x->mark;
+	mp->new_mark               = new_mark_buf;
+}
+
 int xfrm_migrate(const struct xfrm_selector *sel, u8 dir, u8 type,
 		 struct xfrm_migrate *m, int num_migrate,
 		 struct xfrm_kmaddress *k, struct net *net,
@@ -4642,6 +4658,7 @@ int xfrm_migrate(const struct xfrm_selector *sel, u8 dir, u8 type,
 		 struct netlink_ext_ack *extack, struct xfrm_user_offload *xuo)
 {
 	int i, err, nx_cur = 0, nx_new = 0;
+	struct xfrm_mark new_marks[XFRM_MAX_DEPTH] = {};
 	struct xfrm_policy *pol = NULL;
 	struct xfrm_state *x, *xc;
 	struct xfrm_state *x_cur[XFRM_MAX_DEPTH];
@@ -4674,6 +4691,8 @@ int xfrm_migrate(const struct xfrm_selector *sel, u8 dir, u8 type,
 			nx_cur++;
 			mp->encap = encap;
 			mp->xuo = xuo;
+			xfrm_migrate_copy_old(mp, x, &new_marks[i]);
+
 			xc = xfrm_state_migrate(x, mp, net, extack);
 			if (xc) {
 				x_new[nx_new] = xc;
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 1ee114f8515d..25d54c44fd94 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -1974,11 +1974,25 @@ static struct xfrm_state *xfrm_state_clone_and_setup(struct xfrm_state *orig,
 		goto out;
 
 	memcpy(&x->id, &orig->id, sizeof(x->id));
-	memcpy(&x->sel, &orig->sel, sizeof(x->sel));
+	if (m->msg_type == XFRM_MSG_MIGRATE_STATE) {
+		if (m->flags & XFRM_MIGRATE_STATE_UPDATE_SEL) {
+			u8 prefixlen = (m->new_family == AF_INET6) ? 128 : 32;
+
+			memcpy(&x->sel, &orig->sel, sizeof(x->sel));
+			x->sel.family      = m->new_family;
+			x->sel.prefixlen_d = prefixlen;
+			x->sel.prefixlen_s = prefixlen;
+			memcpy(&x->sel.daddr, &m->new_daddr, sizeof(x->sel.daddr));
+			memcpy(&x->sel.saddr, &m->new_saddr, sizeof(x->sel.saddr));
+		} else {
+			x->sel = *m->new_sel;
+		}
+	} else {
+		memcpy(&x->sel, &orig->sel, sizeof(x->sel));
+	}
 	memcpy(&x->lft, &orig->lft, sizeof(x->lft));
 	x->props.mode = orig->props.mode;
 	x->props.replay_window = orig->props.replay_window;
-	x->props.reqid = orig->props.reqid;
 
 	if (orig->aalg) {
 		x->aalg = xfrm_algo_auth_clone(orig->aalg);
@@ -2011,8 +2025,8 @@ static struct xfrm_state *xfrm_state_clone_and_setup(struct xfrm_state *orig,
 		x->encap = kmemdup(m->encap, sizeof(*x->encap), GFP_KERNEL);
 		if (!x->encap)
 			goto error;
-		x->mapping_maxage = orig->mapping_maxage;
-		x->nat_keepalive_interval = orig->nat_keepalive_interval;
+		x->mapping_maxage = m->mapping_maxage;
+		x->nat_keepalive_interval = m->nat_keepalive_interval;
 	}
 
 	if (orig->security)
@@ -2029,8 +2043,9 @@ static struct xfrm_state *xfrm_state_clone_and_setup(struct xfrm_state *orig,
 	if (xfrm_replay_clone(x, orig))
 		goto error;
 
-	memcpy(&x->mark, &orig->mark, sizeof(x->mark));
-	memcpy(&x->props.smark, &orig->props.smark, sizeof(x->props.smark));
+	x->mark = m->new_mark ? *m->new_mark : m->old_mark;
+
+	x->props.smark = m->smark;
 
 	x->props.flags = orig->props.flags;
 	x->props.extra_flags = orig->props.extra_flags;
@@ -2053,7 +2068,7 @@ static struct xfrm_state *xfrm_state_clone_and_setup(struct xfrm_state *orig,
 			goto error;
 	}
 
-
+	x->props.reqid = m->new_reqid;
 	x->props.family = m->new_family;
 	memcpy(&x->id.daddr, &m->new_daddr, sizeof(x->id.daddr));
 	memcpy(&x->props.saddr, &m->new_saddr, sizeof(x->props.saddr));
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index fe0cf824f072..46e506548122 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1318,7 +1318,7 @@ static int copy_to_user_encap(struct xfrm_encap_tmpl *ep, struct sk_buff *skb)
 	return 0;
 }
 
-static int xfrm_smark_put(struct sk_buff *skb, struct xfrm_mark *m)
+static int xfrm_smark_put(struct sk_buff *skb, const struct xfrm_mark *m)
 {
 	int ret = 0;
 
@@ -3059,6 +3059,25 @@ static int xfrm_add_acquire(struct sk_buff *skb, struct nlmsghdr *nlh,
 }
 
 #ifdef CONFIG_XFRM_MIGRATE
+static void copy_from_user_migrate_state(struct xfrm_migrate *ma,
+					 const struct xfrm_user_migrate_state *um)
+{
+	memcpy(&ma->old_daddr, &um->id.daddr, sizeof(ma->old_daddr));
+	memcpy(&ma->new_daddr, &um->new_daddr, sizeof(ma->new_daddr));
+	memcpy(&ma->new_saddr, &um->new_saddr, sizeof(ma->new_saddr));
+
+	ma->proto = um->id.proto;
+	ma->new_reqid = um->new_reqid;
+
+	ma->old_family = um->id.family;
+	ma->new_family = um->new_family;
+
+	ma->old_mark = um->old_mark;
+	ma->flags    = um->flags;
+	ma->new_sel  = &um->new_sel;
+	ma->msg_type = XFRM_MSG_MIGRATE_STATE;
+}
+
 static int copy_from_user_migrate(struct xfrm_migrate *ma,
 				  struct xfrm_kmaddress *k,
 				  struct nlattr **attrs, int *num,
@@ -3098,6 +3117,7 @@ static int copy_from_user_migrate(struct xfrm_migrate *ma,
 
 		ma->old_family = um->old_family;
 		ma->new_family = um->new_family;
+		ma->msg_type   = XFRM_MSG_MIGRATE;
 	}
 
 	*num = i;
@@ -3108,7 +3128,7 @@ static int xfrm_do_migrate(struct sk_buff *skb, struct nlmsghdr *nlh,
 			   struct nlattr **attrs, struct netlink_ext_ack *extack)
 {
 	struct xfrm_userpolicy_id *pi = nlmsg_data(nlh);
-	struct xfrm_migrate m[XFRM_MAX_DEPTH];
+	struct xfrm_migrate m[XFRM_MAX_DEPTH] = {};
 	struct xfrm_kmaddress km, *kmp;
 	u8 type;
 	int err;
@@ -3161,7 +3181,268 @@ static int xfrm_do_migrate(struct sk_buff *skb, struct nlmsghdr *nlh,
 	kfree(xuo);
 	return err;
 }
+
+static int build_migrate_state(struct sk_buff *skb,
+			       const struct xfrm_user_migrate_state *um,
+			       const struct xfrm_migrate *m,
+			       u8 dir, u32 portid, u32 seq)
+{
+	int err;
+	struct nlmsghdr *nlh;
+	struct xfrm_user_migrate_state *hdr;
+
+	nlh = nlmsg_put(skb, portid, seq, XFRM_MSG_MIGRATE_STATE,
+			sizeof(struct xfrm_user_migrate_state), 0);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	hdr = nlmsg_data(nlh);
+	*hdr = *um;
+	hdr->new_sel = *m->new_sel;
+
+	if (m->encap) {
+		err = nla_put(skb, XFRMA_ENCAP, sizeof(*m->encap), m->encap);
+		if (err)
+			goto out_cancel;
+	}
+
+	if (m->xuo) {
+		err = nla_put(skb, XFRMA_OFFLOAD_DEV, sizeof(*m->xuo), m->xuo);
+		if (err)
+			goto out_cancel;
+	}
+
+	if (m->new_mark) {
+		err = nla_put(skb, XFRMA_MARK, sizeof(*m->new_mark),
+			      m->new_mark);
+		if (err)
+			goto out_cancel;
+	}
+
+	err = xfrm_smark_put(skb, &m->smark);
+	if (err)
+		goto out_cancel;
+
+	if (m->mapping_maxage) {
+		err = nla_put_u32(skb, XFRMA_MTIMER_THRESH, m->mapping_maxage);
+		if (err)
+			goto out_cancel;
+	}
+
+	if (m->nat_keepalive_interval) {
+		err = nla_put_u32(skb, XFRMA_NAT_KEEPALIVE_INTERVAL,
+				  m->nat_keepalive_interval);
+		if (err)
+			goto out_cancel;
+	}
+
+	if (dir) {
+		err = nla_put_u8(skb, XFRMA_SA_DIR, dir);
+		if (err)
+			goto out_cancel;
+	}
+
+	nlmsg_end(skb, nlh);
+	return 0;
+
+out_cancel:
+	nlmsg_cancel(skb, nlh);
+	return err;
+}
+
+static unsigned int xfrm_migrate_state_msgsize(const struct xfrm_migrate *m,
+					       u8 dir)
+{
+	return NLMSG_ALIGN(sizeof(struct xfrm_user_migrate_state)) +
+		(m->encap ? nla_total_size(sizeof(struct xfrm_encap_tmpl)) : 0) +
+		(m->xuo ? nla_total_size(sizeof(struct xfrm_user_offload)) : 0) +
+		(m->new_mark ? nla_total_size(sizeof(struct xfrm_mark)) : 0) +
+		(m->smark.v ? nla_total_size(sizeof(u32)) * 2 : 0) + /* SET_MARK + SET_MARK_MASK */
+		(m->mapping_maxage ? nla_total_size(sizeof(u32)) : 0) +
+		(m->nat_keepalive_interval ? nla_total_size(sizeof(u32)) : 0) +
+		(dir ? nla_total_size(sizeof(u8)) : 0); /* XFRMA_SA_DIR */
+}
+
+static int xfrm_send_migrate_state(const struct xfrm_user_migrate_state *um,
+				   const struct xfrm_migrate *m,
+				   u8 dir, u32 portid, u32 seq)
+{
+	int err;
+	struct sk_buff *skb;
+	struct net *net = &init_net;
+
+	skb = nlmsg_new(xfrm_migrate_state_msgsize(m, dir), GFP_ATOMIC);
+	if (!skb)
+		return -ENOMEM;
+
+	err = build_migrate_state(skb, um, m, dir, portid, seq);
+	if (err < 0) {
+		kfree_skb(skb);
+		return err;
+	}
+
+	return xfrm_nlmsg_multicast(net, skb, 0, XFRMNLGRP_MIGRATE);
+}
+
+static int xfrm_do_migrate_state(struct sk_buff *skb, struct nlmsghdr *nlh,
+				 struct nlattr **attrs, struct netlink_ext_ack *extack)
+{
+	struct xfrm_user_migrate_state *um = nlmsg_data(nlh);
+	struct net *net = sock_net(skb->sk);
+	struct xfrm_user_offload xuo = {};
+	struct xfrm_migrate m = {};
+	struct xfrm_state *xc;
+	struct xfrm_state *x;
+	int err;
+
+	if (!um->id.spi) {
+		NL_SET_ERR_MSG(extack, "Invalid SPI 0x0");
+		return -EINVAL;
+	}
+
+	if (um->reserved) {
+		NL_SET_ERR_MSG(extack, "Reserved field must be zero");
+		return -EINVAL;
+	}
+
+	if (um->flags & ~(XFRM_MIGRATE_STATE_NO_OFFLOAD |
+			  XFRM_MIGRATE_STATE_UPDATE_SEL)) {
+		NL_SET_ERR_MSG(extack, "Unknown flags in XFRM_MSG_MIGRATE_STATE");
+		return -EINVAL;
+	}
+
+	if ((um->flags & XFRM_MIGRATE_STATE_NO_OFFLOAD) &&
+	    attrs[XFRMA_OFFLOAD_DEV]) {
+		NL_SET_ERR_MSG(extack,
+			       "XFRM_MIGRATE_STATE_NO_OFFLOAD and XFRMA_OFFLOAD_DEV are mutually exclusive");
+		return -EINVAL;
+	}
+
+	copy_from_user_migrate_state(&m, um);
+
+	x = xfrm_state_lookup(net, m.old_mark.v & m.old_mark.m,
+			      &um->id.daddr, um->id.spi,
+			      um->id.proto, um->id.family);
+	if (!x) {
+		NL_SET_ERR_MSG(extack, "Can not find state");
+		return -ESRCH;
+	}
+
+	if (um->flags & XFRM_MIGRATE_STATE_UPDATE_SEL) {
+		u8 prefixlen = (x->sel.family == AF_INET6) ? 128 : 32;
+
+		if (x->sel.prefixlen_s != x->sel.prefixlen_d ||
+		    x->sel.prefixlen_d != prefixlen ||
+		    !xfrm_addr_equal(&x->sel.daddr, &x->id.daddr, x->sel.family) ||
+		    !xfrm_addr_equal(&x->sel.saddr, &x->props.saddr, x->sel.family)) {
+			NL_SET_ERR_MSG(extack,
+				       "SA selector is not a single-host match for SA addresses");
+			err = -EINVAL;
+			goto out;
+		}
+	}
+
+	if (attrs[XFRMA_ENCAP]) {
+		m.encap = nla_data(attrs[XFRMA_ENCAP]);
+		if (m.encap->encap_type == 0) {
+			m.encap = NULL; /* sentinel: remove encap */
+		} else if (m.encap->encap_type != UDP_ENCAP_ESPINUDP) {
+			NL_SET_ERR_MSG(extack, "Unsupported encapsulation type");
+			err = -EINVAL;
+			goto out;
+		}
+	} else {
+		m.encap = x->encap; /* omit-to-inherit */
+	}
+
+	if (attrs[XFRMA_MTIMER_THRESH]) {
+		err = verify_mtimer_thresh(!!m.encap, x->dir, extack);
+		if (err)
+			goto out;
+	}
+
+	if (attrs[XFRMA_NAT_KEEPALIVE_INTERVAL] &&
+	    nla_get_u32(attrs[XFRMA_NAT_KEEPALIVE_INTERVAL]) && !m.encap) {
+		NL_SET_ERR_MSG(extack,
+			       "NAT_KEEPALIVE_INTERVAL requires encapsulation");
+		err = -EINVAL;
+		goto out;
+	}
+
+	if (attrs[XFRMA_OFFLOAD_DEV]) {
+		m.xuo = nla_data(attrs[XFRMA_OFFLOAD_DEV]);
+	} else if (!(um->flags & XFRM_MIGRATE_STATE_NO_OFFLOAD) && x->xso.dev) {
+		xuo.ifindex = x->xso.dev->ifindex;
+		if (x->xso.dir == XFRM_DEV_OFFLOAD_IN)
+			xuo.flags = XFRM_OFFLOAD_INBOUND;
+		if (x->xso.type == XFRM_DEV_OFFLOAD_PACKET)
+			xuo.flags |= XFRM_OFFLOAD_PACKET;
+		m.xuo = &xuo;
+	}
+
+	if (attrs[XFRMA_MARK])
+		m.new_mark = nla_data(attrs[XFRMA_MARK]);
+
+	if (attrs[XFRMA_SET_MARK])
+		xfrm_smark_init(attrs, &m.smark);
+	else
+		m.smark = x->props.smark;
+
+	m.mapping_maxage = attrs[XFRMA_MTIMER_THRESH] ?
+		nla_get_u32(attrs[XFRMA_MTIMER_THRESH]) : x->mapping_maxage;
+	m.nat_keepalive_interval = attrs[XFRMA_NAT_KEEPALIVE_INTERVAL] ?
+		nla_get_u32(attrs[XFRMA_NAT_KEEPALIVE_INTERVAL]) :
+		x->nat_keepalive_interval;
+
+	xc = xfrm_state_migrate_create(x, &m, net, extack);
+	if (!xc) {
+		NL_SET_ERR_MSG_WEAK(extack, "State migration clone failed");
+		err = -EINVAL;
+		goto out;
+	}
+
+	spin_lock_bh(&x->lock);
+	xfrm_migrate_sync(xc, x); /* to prevent SN/IV reuse */
+	__xfrm_state_delete(x);
+	spin_unlock_bh(&x->lock);
+
+	err = xfrm_state_migrate_install(x, xc, &m, extack);
+	if (err < 0) {
+		/*
+		 * In this rare case both the old SA and the new SA
+		 * will disappear.
+		 * Alternatives risk duplicate SN/IV usage which must not occur.
+		 * Userspace must handle this error, -EEXIST.
+		 */
+		goto out;
+	}
+
+	/* Restore encap cleared by sentinel (type=0) during migration. */
+	if (attrs[XFRMA_ENCAP])
+		m.encap = nla_data(attrs[XFRMA_ENCAP]);
+
+	m.new_sel = &xc->sel;
+
+	err = xfrm_send_migrate_state(um, &m, xc->dir,
+				      nlh->nlmsg_pid, nlh->nlmsg_seq);
+	if (err < 0) {
+		NL_SET_ERR_MSG(extack, "Failed to send migration notification");
+		err = 0;
+	}
+
+out:
+	xfrm_state_put(x);
+	return err;
+}
+
 #else
+static int xfrm_do_migrate_state(struct sk_buff *skb, struct nlmsghdr *nlh,
+				 struct nlattr **attrs, struct netlink_ext_ack *extack)
+{
+	NL_SET_ERR_MSG(extack, "XFRM_MSG_MIGRATE_STATE is not supported");
+	return -ENOPROTOOPT;
+}
+
 static int xfrm_do_migrate(struct sk_buff *skb, struct nlmsghdr *nlh,
 			   struct nlattr **attrs, struct netlink_ext_ack *extack)
 {
@@ -3314,6 +3595,7 @@ const int xfrm_msg_min[XFRM_NR_MSGTYPES] = {
 	[XFRM_MSG_GETSPDINFO  - XFRM_MSG_BASE] = sizeof(u32),
 	[XFRM_MSG_SETDEFAULT  - XFRM_MSG_BASE] = XMSGSIZE(xfrm_userpolicy_default),
 	[XFRM_MSG_GETDEFAULT  - XFRM_MSG_BASE] = XMSGSIZE(xfrm_userpolicy_default),
+	[XFRM_MSG_MIGRATE_STATE - XFRM_MSG_BASE] = XMSGSIZE(xfrm_user_migrate_state),
 };
 EXPORT_SYMBOL_GPL(xfrm_msg_min);
 
@@ -3407,6 +3689,7 @@ static const struct xfrm_link {
 	[XFRM_MSG_GETSPDINFO  - XFRM_MSG_BASE] = { .doit = xfrm_get_spdinfo   },
 	[XFRM_MSG_SETDEFAULT  - XFRM_MSG_BASE] = { .doit = xfrm_set_default   },
 	[XFRM_MSG_GETDEFAULT  - XFRM_MSG_BASE] = { .doit = xfrm_get_default   },
+	[XFRM_MSG_MIGRATE_STATE - XFRM_MSG_BASE] = { .doit = xfrm_do_migrate_state },
 };
 
 static int xfrm_reject_unused_attr(int type, struct nlattr **attrs,
diff --git a/security/selinux/nlmsgtab.c b/security/selinux/nlmsgtab.c
index 2c0b07f9fbbd..655d2616c9d2 100644
--- a/security/selinux/nlmsgtab.c
+++ b/security/selinux/nlmsgtab.c
@@ -128,6 +128,7 @@ static const struct nlmsg_perm nlmsg_xfrm_perms[] = {
 	{ XFRM_MSG_MAPPING, NETLINK_XFRM_SOCKET__NLMSG_READ },
 	{ XFRM_MSG_SETDEFAULT, NETLINK_XFRM_SOCKET__NLMSG_WRITE },
 	{ XFRM_MSG_GETDEFAULT, NETLINK_XFRM_SOCKET__NLMSG_READ },
+	{ XFRM_MSG_MIGRATE_STATE, NETLINK_XFRM_SOCKET__NLMSG_WRITE },
 };
 
 static const struct nlmsg_perm nlmsg_audit_perms[] = {
@@ -203,7 +204,7 @@ int selinux_nlmsg_lookup(u16 sclass, u16 nlmsg_type, u32 *perm)
 		 * structures at the top of this file with the new mappings
 		 * before updating the BUILD_BUG_ON() macro!
 		 */
-		BUILD_BUG_ON(XFRM_MSG_MAX != XFRM_MSG_GETDEFAULT);
+		BUILD_BUG_ON(XFRM_MSG_MAX != XFRM_MSG_MIGRATE_STATE);
 
 		if (selinux_policycap_netlink_xperm()) {
 			*perm = NETLINK_XFRM_SOCKET__NLMSG;

-- 
2.47.3