From: Justin Iurman <justin.iurman@6wind.com>
To: netdev@vger.kernel.org
Cc: andrea.mayer@uniroma2.it, davem@davemloft.net,
edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
horms@kernel.org, justin.iurman@gmail.com,
nicolas.dichtel@6wind.com, stefano.salsano@uniroma2.it,
Justin Iurman <justin.iurman@6wind.com>,
David Ahern <dsahern@kernel.org>
Subject: [PATCH net-next v4 1/2] seg6: add per-route tunnel source address
Date: Fri, 20 Mar 2026 14:59:08 +0100 [thread overview]
Message-ID: <20260320135909.1729313-2-justin.iurman@6wind.com> (raw)
In-Reply-To: <20260320135909.1729313-1-justin.iurman@6wind.com>
Add SEG6_IPTUNNEL_SRC in the uapi for users to configure a specific
tunnel source address. Make seg6_iptunnel handle the new attribute
correctly. It has priority over the configured per-netns tunnel
source address, if any.
Cc: David Ahern <dsahern@kernel.org>
Signed-off-by: Justin Iurman <justin.iurman@6wind.com>
---
include/uapi/linux/seg6_iptunnel.h | 1 +
net/ipv6/seg6_iptunnel.c | 114 +++++++++++++++++++++--------
2 files changed, 84 insertions(+), 31 deletions(-)
diff --git a/include/uapi/linux/seg6_iptunnel.h b/include/uapi/linux/seg6_iptunnel.h
index ae78791372b8..485889b19900 100644
--- a/include/uapi/linux/seg6_iptunnel.h
+++ b/include/uapi/linux/seg6_iptunnel.h
@@ -20,6 +20,7 @@
enum {
SEG6_IPTUNNEL_UNSPEC,
SEG6_IPTUNNEL_SRH,
+ SEG6_IPTUNNEL_SRC, /* struct in6_addr */
__SEG6_IPTUNNEL_MAX,
};
#define SEG6_IPTUNNEL_MAX (__SEG6_IPTUNNEL_MAX - 1)
diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c
index 3e1b9991131a..e76cc0cc481e 100644
--- a/net/ipv6/seg6_iptunnel.c
+++ b/net/ipv6/seg6_iptunnel.c
@@ -49,6 +49,7 @@ static size_t seg6_lwt_headroom(struct seg6_iptunnel_encap *tuninfo)
struct seg6_lwt {
struct dst_cache cache;
+ struct in6_addr tunsrc;
struct seg6_iptunnel_encap tuninfo[];
};
@@ -65,6 +66,7 @@ seg6_encap_lwtunnel(struct lwtunnel_state *lwt)
static const struct nla_policy seg6_iptunnel_policy[SEG6_IPTUNNEL_MAX + 1] = {
[SEG6_IPTUNNEL_SRH] = { .type = NLA_BINARY },
+ [SEG6_IPTUNNEL_SRC] = NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
};
static int nla_put_srh(struct sk_buff *skb, int attrtype,
@@ -87,23 +89,32 @@ static int nla_put_srh(struct sk_buff *skb, int attrtype,
}
static void set_tun_src(struct net *net, struct net_device *dev,
- struct in6_addr *daddr, struct in6_addr *saddr)
+ struct in6_addr *daddr, struct in6_addr *saddr,
+ struct in6_addr *route_tunsrc)
{
struct seg6_pernet_data *sdata = seg6_pernet(net);
struct in6_addr *tun_src;
- rcu_read_lock();
-
- tun_src = rcu_dereference(sdata->tun_src);
-
- if (!ipv6_addr_any(tun_src)) {
- memcpy(saddr, tun_src, sizeof(struct in6_addr));
+ /* Priority order to select tunnel source address:
+ * 1. per route source address (if configured)
+ * 2. per network namespace source address (if configured)
+ * 3. dynamic resolution
+ */
+ if (route_tunsrc && !ipv6_addr_any(route_tunsrc)) {
+ memcpy(saddr, route_tunsrc, sizeof(struct in6_addr));
} else {
- ipv6_dev_get_saddr(net, dev, daddr, IPV6_PREFER_SRC_PUBLIC,
- saddr);
- }
+ rcu_read_lock();
+ tun_src = rcu_dereference(sdata->tun_src);
+
+ if (!ipv6_addr_any(tun_src)) {
+ memcpy(saddr, tun_src, sizeof(struct in6_addr));
+ } else {
+ ipv6_dev_get_saddr(net, dev, daddr,
+ IPV6_PREFER_SRC_PUBLIC, saddr);
+ }
- rcu_read_unlock();
+ rcu_read_unlock();
+ }
}
/* Compute flowlabel for outer IPv6 header */
@@ -125,7 +136,8 @@ static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb,
}
static int __seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh,
- int proto, struct dst_entry *cache_dst)
+ int proto, struct dst_entry *cache_dst,
+ struct in6_addr *route_tunsrc)
{
struct dst_entry *dst = skb_dst(skb);
struct net_device *dev = dst_dev(dst);
@@ -182,7 +194,7 @@ static int __seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh,
isrh->nexthdr = proto;
hdr->daddr = isrh->segments[isrh->first_segment];
- set_tun_src(net, dev, &hdr->daddr, &hdr->saddr);
+ set_tun_src(net, dev, &hdr->daddr, &hdr->saddr, route_tunsrc);
#ifdef CONFIG_IPV6_SEG6_HMAC
if (sr_has_hmac(isrh)) {
@@ -202,14 +214,15 @@ static int __seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh,
/* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */
int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
{
- return __seg6_do_srh_encap(skb, osrh, proto, NULL);
+ return __seg6_do_srh_encap(skb, osrh, proto, NULL, NULL);
}
EXPORT_SYMBOL_GPL(seg6_do_srh_encap);
/* encapsulate an IPv6 packet within an outer IPv6 header with reduced SRH */
static int seg6_do_srh_encap_red(struct sk_buff *skb,
struct ipv6_sr_hdr *osrh, int proto,
- struct dst_entry *cache_dst)
+ struct dst_entry *cache_dst,
+ struct in6_addr *route_tunsrc)
{
__u8 first_seg = osrh->first_segment;
struct dst_entry *dst = skb_dst(skb);
@@ -272,7 +285,7 @@ static int seg6_do_srh_encap_red(struct sk_buff *skb,
if (skip_srh) {
hdr->nexthdr = proto;
- set_tun_src(net, dev, &hdr->daddr, &hdr->saddr);
+ set_tun_src(net, dev, &hdr->daddr, &hdr->saddr, route_tunsrc);
goto out;
}
@@ -308,7 +321,7 @@ static int seg6_do_srh_encap_red(struct sk_buff *skb,
srcaddr:
isrh->nexthdr = proto;
- set_tun_src(net, dev, &hdr->daddr, &hdr->saddr);
+ set_tun_src(net, dev, &hdr->daddr, &hdr->saddr, route_tunsrc);
#ifdef CONFIG_IPV6_SEG6_HMAC
if (unlikely(!skip_srh && sr_has_hmac(isrh))) {
@@ -383,9 +396,11 @@ static int seg6_do_srh(struct sk_buff *skb, struct dst_entry *cache_dst)
{
struct dst_entry *dst = skb_dst(skb);
struct seg6_iptunnel_encap *tinfo;
+ struct seg6_lwt *slwt;
int proto, err = 0;
- tinfo = seg6_encap_lwtunnel(dst->lwtstate);
+ slwt = seg6_lwt_lwtunnel(dst->lwtstate);
+ tinfo = slwt->tuninfo;
switch (tinfo->mode) {
case SEG6_IPTUN_MODE_INLINE:
@@ -410,11 +425,11 @@ static int seg6_do_srh(struct sk_buff *skb, struct dst_entry *cache_dst)
return -EINVAL;
if (tinfo->mode == SEG6_IPTUN_MODE_ENCAP)
- err = __seg6_do_srh_encap(skb, tinfo->srh,
- proto, cache_dst);
+ err = __seg6_do_srh_encap(skb, tinfo->srh, proto,
+ cache_dst, &slwt->tunsrc);
else
- err = seg6_do_srh_encap_red(skb, tinfo->srh,
- proto, cache_dst);
+ err = seg6_do_srh_encap_red(skb, tinfo->srh, proto,
+ cache_dst, &slwt->tunsrc);
if (err)
return err;
@@ -436,12 +451,12 @@ static int seg6_do_srh(struct sk_buff *skb, struct dst_entry *cache_dst)
if (tinfo->mode == SEG6_IPTUN_MODE_L2ENCAP)
err = __seg6_do_srh_encap(skb, tinfo->srh,
- IPPROTO_ETHERNET,
- cache_dst);
+ IPPROTO_ETHERNET, cache_dst,
+ &slwt->tunsrc);
else
err = seg6_do_srh_encap_red(skb, tinfo->srh,
- IPPROTO_ETHERNET,
- cache_dst);
+ IPPROTO_ETHERNET, cache_dst,
+ &slwt->tunsrc);
if (err)
return err;
@@ -678,6 +693,10 @@ static int seg6_build_state(struct net *net, struct nlattr *nla,
if (family != AF_INET6)
return -EINVAL;
+ if (tb[SEG6_IPTUNNEL_SRC]) {
+ NL_SET_ERR_MSG(extack, "incompatible mode for tunsrc");
+ return -EINVAL;
+ }
break;
case SEG6_IPTUN_MODE_ENCAP:
break;
@@ -702,13 +721,23 @@ static int seg6_build_state(struct net *net, struct nlattr *nla,
slwt = seg6_lwt_lwtunnel(newts);
err = dst_cache_init(&slwt->cache, GFP_ATOMIC);
- if (err) {
- kfree(newts);
- return err;
- }
+ if (err)
+ goto free_lwt_state;
memcpy(&slwt->tuninfo, tuninfo, tuninfo_len);
+ if (tb[SEG6_IPTUNNEL_SRC]) {
+ slwt->tunsrc = nla_get_in6_addr(tb[SEG6_IPTUNNEL_SRC]);
+
+ if (ipv6_addr_any(&slwt->tunsrc) ||
+ ipv6_addr_is_multicast(&slwt->tunsrc) ||
+ ipv6_addr_loopback(&slwt->tunsrc)) {
+ NL_SET_ERR_MSG(extack, "invalid tunsrc address");
+ err = -EINVAL;
+ goto free_dst_cache;
+ }
+ }
+
newts->type = LWTUNNEL_ENCAP_SEG6;
newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
@@ -720,6 +749,12 @@ static int seg6_build_state(struct net *net, struct nlattr *nla,
*ts = newts;
return 0;
+
+free_dst_cache:
+ dst_cache_destroy(&slwt->cache);
+free_lwt_state:
+ kfree(newts);
+ return err;
}
static void seg6_destroy_state(struct lwtunnel_state *lwt)
@@ -731,29 +766,46 @@ static int seg6_fill_encap_info(struct sk_buff *skb,
struct lwtunnel_state *lwtstate)
{
struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
+ struct seg6_lwt *slwt = seg6_lwt_lwtunnel(lwtstate);
if (nla_put_srh(skb, SEG6_IPTUNNEL_SRH, tuninfo))
return -EMSGSIZE;
+ if (!ipv6_addr_any(&slwt->tunsrc) &&
+ nla_put_in6_addr(skb, SEG6_IPTUNNEL_SRC, &slwt->tunsrc))
+ return -EMSGSIZE;
+
return 0;
}
static int seg6_encap_nlsize(struct lwtunnel_state *lwtstate)
{
struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
+ struct seg6_lwt *slwt = seg6_lwt_lwtunnel(lwtstate);
+ int nlsize;
+
+ nlsize = nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo));
- return nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo));
+ if (!ipv6_addr_any(&slwt->tunsrc))
+ nlsize += nla_total_size(sizeof(slwt->tunsrc));
+
+ return nlsize;
}
static int seg6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
{
struct seg6_iptunnel_encap *a_hdr = seg6_encap_lwtunnel(a);
struct seg6_iptunnel_encap *b_hdr = seg6_encap_lwtunnel(b);
+ struct seg6_lwt *a_slwt = seg6_lwt_lwtunnel(a);
+ struct seg6_lwt *b_slwt = seg6_lwt_lwtunnel(b);
int len = SEG6_IPTUN_ENCAP_SIZE(a_hdr);
if (len != SEG6_IPTUN_ENCAP_SIZE(b_hdr))
return 1;
+ if (!ipv6_addr_equal(&a_slwt->tunsrc, &b_slwt->tunsrc))
+ return 1;
+
return memcmp(a_hdr, b_hdr, len);
}
--
2.39.2
next prev parent reply other threads:[~2026-03-20 13:59 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-20 13:59 [PATCH net-next v4 0/2] Add support for per-route seg6 tunsrc Justin Iurman
2026-03-20 13:59 ` Justin Iurman [this message]
2026-03-22 16:47 ` [PATCH net-next v4 1/2] seg6: add per-route tunnel source address Andrea Mayer
2026-03-20 13:59 ` [PATCH net-next v4 2/2] selftests: add check for seg6 tunsrc Justin Iurman
2026-03-23 3:27 ` Andrea Mayer
2026-03-24 8:09 ` Justin Iurman
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