diff mbox series

[net-next,09/12] gtp: add helper function to build GTP packets from an IPv4 packet

Message ID 20240425105138.1361098-10-pablo@netfilter.org (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series [net-next,01/12] gtp: remove useless initialization | expand

Checks

Context Check Description
netdev/series_format success Pull request is its own cover letter
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 926 this patch: 926
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 2 maintainers not CCed: osmocom-net-gprs@lists.osmocom.org laforge@gnumonks.org
netdev/build_clang success Errors and warnings before: 937 this patch: 937
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 937 this patch: 937
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 107 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Pablo Neira Ayuso April 25, 2024, 10:51 a.m. UTC 
Add routine to attach an IPv4 route for the encapsulated packet, deal
with Path MTU and push GTP header.

This helper function will be used to deal with IPv6-in-IPv4-GTP.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 drivers/net/gtp.c | 69 ++++++++++++++++++++++++++++-------------------
 1 file changed, 42 insertions(+), 27 deletions(-)
diff mbox series

Patch

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 5e4f3102fffe..3293528bd365 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -983,33 +983,16 @@  static inline void gtp_set_pktinfo_ipv6(struct gtp_pktinfo *pktinfo,
 	pktinfo->dev	= dev;
 }
 
-static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
-			     struct gtp_pktinfo *pktinfo)
+static int gtp_build_skb_outer_ip4(struct sk_buff *skb, struct net_device *dev,
+				   struct gtp_pktinfo *pktinfo,
+				   struct pdp_ctx *pctx, __u8 tos,
+				   __be16 frag_off)
 {
-	struct gtp_dev *gtp = netdev_priv(dev);
-	struct pdp_ctx *pctx;
 	struct rtable *rt;
 	struct flowi4 fl4;
-	struct iphdr *iph;
 	__be16 df;
 	int mtu;
 
-	/* Read the IP destination address and resolve the PDP context.
-	 * Prepend PDP header with TEI/TID from PDP ctx.
-	 */
-	iph = ip_hdr(skb);
-	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);
-		return -ENOENT;
-	}
-	netdev_dbg(dev, "found PDP context %p\n", pctx);
-
 	rt = ip4_route_output_gtp(&fl4, pctx->sk, pctx->peer.addr.s_addr,
 				  inet_sk(pctx->sk)->inet_saddr);
 	if (IS_ERR(rt)) {
@@ -1027,7 +1010,7 @@  static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
 	}
 
 	/* This is similar to tnl_update_pmtu(). */
-	df = iph->frag_off;
+	df = frag_off;
 	if (df) {
 		mtu = dst_mtu(&rt->dst) - dev->hard_header_len -
 			sizeof(struct iphdr) - sizeof(struct udphdr);
@@ -1045,7 +1028,7 @@  static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
 
 	skb_dst_update_pmtu_no_confirm(skb, mtu);
 
-	if (iph->frag_off & htons(IP_DF) &&
+	if (frag_off & htons(IP_DF) &&
 	    ((!skb_is_gso(skb) && skb->len > mtu) ||
 	     (skb_is_gso(skb) && !skb_gso_validate_network_len(skb, mtu)))) {
 		netdev_dbg(dev, "packet too big, fragmentation needed\n");
@@ -1054,12 +1037,9 @@  static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
 		goto err_rt;
 	}
 
-	gtp_set_pktinfo_ipv4(pktinfo, pctx->sk, iph->tos, pctx, rt, &fl4, dev);
+	gtp_set_pktinfo_ipv4(pktinfo, pctx->sk, tos, pctx, rt, &fl4, dev);
 	gtp_push_header(skb, pktinfo);
 
-	netdev_dbg(dev, "gtp -> IP src: %pI4 dst: %pI4\n",
-		   &iph->saddr, &iph->daddr);
-
 	return 0;
 err_rt:
 	ip_rt_put(rt);
@@ -1067,6 +1047,41 @@  static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
 	return -EBADMSG;
 }
 
+static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
+			     struct gtp_pktinfo *pktinfo)
+{
+	struct gtp_dev *gtp = netdev_priv(dev);
+	struct pdp_ctx *pctx;
+	struct iphdr *iph;
+	int ret;
+
+	/* Read the IP destination address and resolve the PDP context.
+	 * Prepend PDP header with TEI/TID from PDP ctx.
+	 */
+	iph = ip_hdr(skb);
+	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);
+		return -ENOENT;
+	}
+	netdev_dbg(dev, "found PDP context %p\n", pctx);
+
+	ret = gtp_build_skb_outer_ip4(skb, dev, pktinfo, pctx,
+				      iph->tos, iph->frag_off);
+	if (ret < 0)
+		return ret;
+
+	netdev_dbg(dev, "gtp -> IP src: %pI4 dst: %pI4\n",
+		   &iph->saddr, &iph->daddr);
+
+	return 0;
+}
+
 static int gtp_build_skb_ip6(struct sk_buff *skb, struct net_device *dev,
 			     struct gtp_pktinfo *pktinfo)
 {