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Message-Id: <20170324093358.31374-3-jonas@southpole.se>
Date: Fri, 24 Mar 2017 10:33:58 +0100
From: Jonas Bonn <jonas@...thpole.se>
To: pablo@...filter.org, netdev@...r.kernel.org, laforge@...monks.org
Cc: Jonas Bonn <jonas@...thpole.se>
Subject: [PATCH net-next v3 2/2] gtp: support SGSN-side tunnels
The GTP-tunnel driver is explicitly GGSN-side as it searches for PDP
contexts based on the incoming packets _destination_ address. If we
want to place ourselves on the SGSN side of the tunnel, then we want
to be identifying PDP contexts based on _source_ address.
Let it be noted that in a "real" configuration this module would never
be used: the SGSN normally does not see IP packets as input. The
justification for this functionality is for PGW load-testing applications
where the input to the SGSN is locally generally IP traffic.
This patch adds a "role" argument at GTP-link creation time to specify
whether we are on the GGSN or SGSN side of the tunnel; this flag is then
used to determine which part of the IP packet to use in determining
the PDP context.
Signed-off-by: Jonas Bonn <jonas@...thpole.se>
Acked-by: Pablo Neira Ayuso <pablo@...filter.org>
---
drivers/net/gtp.c | 41 +++++++++++++++++++++++++++++++----------
include/uapi/linux/if_link.h | 7 +++++++
2 files changed, 38 insertions(+), 10 deletions(-)
diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 3806be6..b54d1a3 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -72,6 +72,7 @@ struct gtp_dev {
struct net *net;
struct net_device *dev;
+ unsigned int role;
unsigned int hash_size;
struct hlist_head *tid_hash;
struct hlist_head *addr_hash;
@@ -150,8 +151,8 @@ static struct pdp_ctx *ipv4_pdp_find(struct gtp_dev *gtp, __be32 ms_addr)
return NULL;
}
-static bool gtp_check_src_ms_ipv4(struct sk_buff *skb, struct pdp_ctx *pctx,
- unsigned int hdrlen)
+static bool gtp_check_ms_ipv4(struct sk_buff *skb, struct pdp_ctx *pctx,
+ unsigned int hdrlen, unsigned int role)
{
struct iphdr *iph;
@@ -160,18 +161,22 @@ static bool gtp_check_src_ms_ipv4(struct sk_buff *skb, struct pdp_ctx *pctx,
iph = (struct iphdr *)(skb->data + hdrlen);
- return iph->saddr == pctx->ms_addr_ip4.s_addr;
+ if (role == GTP_ROLE_SGSN) {
+ return iph->daddr == pctx->ms_addr_ip4.s_addr;
+ } else {
+ return iph->saddr == pctx->ms_addr_ip4.s_addr;
+ }
}
-/* Check if the inner IP source address in this packet is assigned to any
+/* Check if the inner IP address in this packet is assigned to any
* existing mobile subscriber.
*/
-static bool gtp_check_src_ms(struct sk_buff *skb, struct pdp_ctx *pctx,
- unsigned int hdrlen)
+static bool gtp_check_ms(struct sk_buff *skb, struct pdp_ctx *pctx,
+ unsigned int hdrlen, unsigned int role)
{
switch (ntohs(skb->protocol)) {
case ETH_P_IP:
- return gtp_check_src_ms_ipv4(skb, pctx, hdrlen);
+ return gtp_check_ms_ipv4(skb, pctx, hdrlen, role);
}
return false;
}
@@ -205,7 +210,7 @@ static int gtp0_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb,
goto out_rcu;
}
- if (!gtp_check_src_ms(skb, pctx, hdrlen)) {
+ if (!gtp_check_ms(skb, pctx, hdrlen, gtp->role)) {
netdev_dbg(gtp->dev, "No PDP ctx for this MS\n");
ret = -1;
goto out_rcu;
@@ -262,7 +267,7 @@ static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb,
goto out_rcu;
}
- if (!gtp_check_src_ms(skb, pctx, hdrlen)) {
+ if (!gtp_check_ms(skb, pctx, hdrlen, gtp->role)) {
netdev_dbg(gtp->dev, "No PDP ctx for this MS\n");
ret = -1;
goto out_rcu;
@@ -491,7 +496,11 @@ static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
* Prepend PDP header with TEI/TID from PDP ctx.
*/
iph = ip_hdr(skb);
- pctx = ipv4_pdp_find(gtp, iph->daddr);
+ if (gtp->role == GTP_ROLE_SGSN) {
+ pctx = ipv4_pdp_find(gtp, iph->saddr);
+ } else {
+ pctx = ipv4_pdp_find(gtp, iph->daddr);
+ }
if (!pctx) {
netdev_dbg(dev, "no PDP ctx found for %pI4, skip\n",
&iph->daddr);
@@ -666,12 +675,23 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev,
int hashsize, err, fd0, fd1;
struct gtp_dev *gtp;
struct gtp_net *gn;
+ unsigned int role;
+
+ if (data[IFLA_GTP_ROLE]) {
+ role = nla_get_u32(data[IFLA_GTP_ROLE]);
+ if (role > GTP_ROLE_SGSN)
+ return -EINVAL;
+ } else {
+ role = GTP_ROLE_GGSN;
+ }
if (!data[IFLA_GTP_FD0] || !data[IFLA_GTP_FD1])
return -EINVAL;
gtp = netdev_priv(dev);
+ gtp->role = role;
+
fd0 = nla_get_u32(data[IFLA_GTP_FD0]);
fd1 = nla_get_u32(data[IFLA_GTP_FD1]);
@@ -723,6 +743,7 @@ static const struct nla_policy gtp_policy[IFLA_GTP_MAX + 1] = {
[IFLA_GTP_FD0] = { .type = NLA_U32 },
[IFLA_GTP_FD1] = { .type = NLA_U32 },
[IFLA_GTP_PDP_HASHSIZE] = { .type = NLA_U32 },
+ [IFLA_GTP_ROLE] = { .type = NLA_U32 },
};
static int gtp_validate(struct nlattr *tb[], struct nlattr *data[])
diff --git a/include/uapi/linux/if_link.h b/include/uapi/linux/if_link.h
index ccde456..da62d8c 100644
--- a/include/uapi/linux/if_link.h
+++ b/include/uapi/linux/if_link.h
@@ -533,11 +533,18 @@ enum {
#define IFLA_PPP_MAX (__IFLA_PPP_MAX - 1)
/* GTP section */
+
+enum ifla_gtp_role {
+ GTP_ROLE_GGSN = 0,
+ GTP_ROLE_SGSN,
+};
+
enum {
IFLA_GTP_UNSPEC,
IFLA_GTP_FD0,
IFLA_GTP_FD1,
IFLA_GTP_PDP_HASHSIZE,
+ IFLA_GTP_ROLE,
__IFLA_GTP_MAX,
};
#define IFLA_GTP_MAX (__IFLA_GTP_MAX - 1)
--
2.9.3
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