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gtp: identify tunnel via GTP device + GTP version + TEID + family
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This allows to define a GTP tunnel for dual stack MS/UE with both IPv4
and IPv6 addresses while using the same TEID via two PDP context
objects.

Signed-off-by: Pablo Neira Ayuso <[email protected]>
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@ummakynes
ummakynes committed May 6, 2024
1 parent e30ea48 commit c75fc0b
Showing 1 changed file with 63 additions and 22 deletions.
85 changes: 63 additions & 22 deletions drivers/net/gtp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -141,31 +141,33 @@ static u32 ipv6_hashfn(const struct in6_addr *ip6)
}

/* Resolve a PDP context structure based on the 64bit TID. */
static struct pdp_ctx *gtp0_pdp_find(struct gtp_dev *gtp, u64 tid)
static struct pdp_ctx *gtp0_pdp_find(struct gtp_dev *gtp, u64 tid, u16 family)
{
struct hlist_head *head;
struct pdp_ctx *pdp;

head = &gtp->tid_hash[gtp0_hashfn(tid) % gtp->hash_size];

hlist_for_each_entry_rcu(pdp, head, hlist_tid) {
if (pdp->gtp_version == GTP_V0 &&
if (pdp->af == family &&
pdp->gtp_version == GTP_V0 &&
pdp->u.v0.tid == tid)
return pdp;
}
return NULL;
}

/* Resolve a PDP context structure based on the 32bit TEI. */
static struct pdp_ctx *gtp1_pdp_find(struct gtp_dev *gtp, u32 tid)
static struct pdp_ctx *gtp1_pdp_find(struct gtp_dev *gtp, u32 tid, u16 family)
{
struct hlist_head *head;
struct pdp_ctx *pdp;

head = &gtp->tid_hash[gtp1u_hashfn(tid) % gtp->hash_size];

hlist_for_each_entry_rcu(pdp, head, hlist_tid) {
if (pdp->gtp_version == GTP_V1 &&
if (pdp->af == family &&
pdp->gtp_version == GTP_V1 &&
pdp->u.v1.i_tei == tid)
return pdp;
}
Expand Down Expand Up @@ -305,15 +307,8 @@ static int gtp_inner_proto(struct sk_buff *skb, unsigned int hdrlen,
}

static int gtp_rx(struct pdp_ctx *pctx, struct sk_buff *skb,
unsigned int hdrlen, unsigned int role)
unsigned int hdrlen, unsigned int role, __u16 inner_proto)
{
__u16 inner_proto;

if (gtp_inner_proto(skb, hdrlen, &inner_proto) < 0) {
netdev_dbg(pctx->dev, "GTP packet does not encapsulate an IP packet\n");
return -1;
}

if (!gtp_check_ms(skb, pctx, hdrlen, role, inner_proto)) {
netdev_dbg(pctx->dev, "No PDP ctx for this MS\n");
return 1;
Expand Down Expand Up @@ -562,13 +557,29 @@ static int gtp0_handle_echo_resp(struct gtp_dev *gtp, struct sk_buff *skb)
msg, 0, GTP_GENL_MCGRP, GFP_ATOMIC);
}

static int gtp_proto_to_family(__u16 proto)
{
switch (proto) {
case ETH_P_IP:
return AF_INET;
case ETH_P_IPV6:
return AF_INET6;
default:
WARN_ON_ONCE(1);
break;
}

return AF_UNSPEC;
}

/* 1 means pass up to the stack, -1 means drop and 0 means decapsulated. */
static int gtp0_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb)
{
unsigned int hdrlen = sizeof(struct udphdr) +
sizeof(struct gtp0_header);
struct gtp0_header *gtp0;
struct pdp_ctx *pctx;
__u16 inner_proto;

if (!pskb_may_pull(skb, hdrlen))
return -1;
Expand All @@ -591,13 +602,19 @@ static int gtp0_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb)
if (gtp0->type != GTP_TPDU)
return 1;

pctx = gtp0_pdp_find(gtp, be64_to_cpu(gtp0->tid));
if (gtp_inner_proto(skb, hdrlen, &inner_proto) < 0) {
netdev_dbg(gtp->dev, "GTP packet does not encapsulate an IP packet\n");
return -1;
}

pctx = gtp0_pdp_find(gtp, be64_to_cpu(gtp0->tid),
gtp_proto_to_family(inner_proto));
if (!pctx) {
netdev_dbg(gtp->dev, "No PDP ctx to decap skb=%p\n", skb);
return 1;
}

return gtp_rx(pctx, skb, hdrlen, gtp->role);
return gtp_rx(pctx, skb, hdrlen, gtp->role, inner_proto);
}

/* msg_type has to be GTP_ECHO_REQ or GTP_ECHO_RSP */
Expand Down Expand Up @@ -768,6 +785,7 @@ static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb)
sizeof(struct gtp1_header);
struct gtp1_header *gtp1;
struct pdp_ctx *pctx;
__u16 inner_proto;

if (!pskb_may_pull(skb, hdrlen))
return -1;
Expand Down Expand Up @@ -803,9 +821,15 @@ static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb)
if (!pskb_may_pull(skb, hdrlen))
return -1;

if (gtp_inner_proto(skb, hdrlen, &inner_proto) < 0) {
netdev_dbg(gtp->dev, "GTP packet does not encapsulate an IP packet\n");
return -1;
}

gtp1 = (struct gtp1_header *)(skb->data + sizeof(struct udphdr));

pctx = gtp1_pdp_find(gtp, ntohl(gtp1->tid));
pctx = gtp1_pdp_find(gtp, ntohl(gtp1->tid),
gtp_proto_to_family(inner_proto));
if (!pctx) {
netdev_dbg(gtp->dev, "No PDP ctx to decap skb=%p\n", skb);
return 1;
Expand All @@ -815,7 +839,7 @@ static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb)
gtp_parse_exthdrs(skb, &hdrlen) < 0)
return -1;

return gtp_rx(pctx, skb, hdrlen, gtp->role);
return gtp_rx(pctx, skb, hdrlen, gtp->role, inner_proto);
}

static void __gtp_encap_destroy(struct sock *sk)
Expand Down Expand Up @@ -1843,10 +1867,12 @@ static struct pdp_ctx *gtp_pdp_add(struct gtp_dev *gtp, struct sock *sk,
found = true;
if (version == GTP_V0)
pctx_tid = gtp0_pdp_find(gtp,
nla_get_u64(info->attrs[GTPA_TID]));
nla_get_u64(info->attrs[GTPA_TID]),
family);
else if (version == GTP_V1)
pctx_tid = gtp1_pdp_find(gtp,
nla_get_u32(info->attrs[GTPA_I_TEI]));
nla_get_u32(info->attrs[GTPA_I_TEI]),
family);
if (pctx_tid)
found = true;

Expand Down Expand Up @@ -2034,6 +2060,12 @@ static struct pdp_ctx *gtp_find_pdp_by_link(struct net *net,
struct nlattr *nla[])
{
struct gtp_dev *gtp;
int family;

if (nla[GTPA_FAMILY])
family = nla_get_u8(nla[GTPA_FAMILY]);
else
family = AF_INET;

gtp = gtp_find_dev(net, nla);
if (!gtp)
Expand All @@ -2042,10 +2074,16 @@ static struct pdp_ctx *gtp_find_pdp_by_link(struct net *net,
if (nla[GTPA_MS_ADDRESS]) {
__be32 ip = nla_get_be32(nla[GTPA_MS_ADDRESS]);

if (family != AF_INET)
return ERR_PTR(-EINVAL);

return ipv4_pdp_find(gtp, ip);
} else if (nla[GTPA_MS_ADDR6]) {
struct in6_addr addr = nla_get_in6_addr(nla[GTPA_MS_ADDR6]);

if (family != AF_INET6)
return ERR_PTR(-EINVAL);

if (addr.s6_addr32[2] ||
addr.s6_addr32[3])
return ERR_PTR(-EADDRNOTAVAIL);
Expand All @@ -2054,10 +2092,13 @@ static struct pdp_ctx *gtp_find_pdp_by_link(struct net *net,
} else if (nla[GTPA_VERSION]) {
u32 gtp_version = nla_get_u32(nla[GTPA_VERSION]);

if (gtp_version == GTP_V0 && nla[GTPA_TID])
return gtp0_pdp_find(gtp, nla_get_u64(nla[GTPA_TID]));
else if (gtp_version == GTP_V1 && nla[GTPA_I_TEI])
return gtp1_pdp_find(gtp, nla_get_u32(nla[GTPA_I_TEI]));
if (gtp_version == GTP_V0 && nla[GTPA_TID]) {
return gtp0_pdp_find(gtp, nla_get_u64(nla[GTPA_TID]),
family);
} else if (gtp_version == GTP_V1 && nla[GTPA_I_TEI]) {
return gtp1_pdp_find(gtp, nla_get_u32(nla[GTPA_I_TEI]),
family);
}
}

return ERR_PTR(-EINVAL);
Expand Down

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