Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Martin KaFai Lau says:

====================
pull-request: bpf-next 2025-09-23

We've added 9 non-merge commits during the last 33 day(s) which contain
a total of 10 files changed, 480 insertions(+), 53 deletions(-).

The main changes are:

1) A new bpf_xdp_pull_data kfunc that supports pulling data from
   a frag into the linear area of a xdp_buff, from Amery Hung.

   This includes changes in the xdp_native.bpf.c selftest, which
   Nimrod's future work depends on.

   It is a merge from a stable branch 'xdp_pull_data' which has
   also been merged to bpf-next.

   There is a conflict with recent changes in 'include/net/xdp.h'
   in the net-next tree that will need to be resolved.

2) A compiler warning fix when CONFIG_NET=n in the recent dynptr
   skb_meta support, from Jakub Sitnicki.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next:
  selftests: drv-net: Pull data before parsing headers
  selftests/bpf: Test bpf_xdp_pull_data
  bpf: Support specifying linear xdp packet data size for BPF_PROG_TEST_RUN
  bpf: Make variables in bpf_prog_test_run_xdp less confusing
  bpf: Clear packet pointers after changing packet data in kfuncs
  bpf: Support pulling non-linear xdp data
  bpf: Allow bpf_xdp_shrink_data to shrink a frag from head and tail
  bpf: Clear pfmemalloc flag when freeing all fragments
  bpf: Return an error pointer for skb metadata when CONFIG_NET=n
====================

Link: https://patch.msgid.link/20250924050303.2466356-1-martin.lau@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 74 insertions, 15 deletions

diff --git a/tools/testing/selftests/net/lib/xdp_native.bpf.c b/tools/testing/selftests/net/lib/xdp_native.bpf.c
index 521ba38f2ddd..df4eea5c192b 100644
--- a/tools/testing/selftests/net/lib/xdp_native.bpf.c
+++ b/tools/testing/selftests/net/lib/xdp_native.bpf.c
@@ -14,6 +14,8 @@
 #define MAX_PAYLOAD_LEN 5000
 #define MAX_HDR_LEN 64
 
+extern int bpf_xdp_pull_data(struct xdp_md *xdp, __u32 len) __ksym __weak;
+
 enum {
 	XDP_MODE = 0,
 	XDP_PORT = 1,
@@ -68,30 +70,57 @@ static void record_stats(struct xdp_md *ctx, __u32 stat_type)
 
 static struct udphdr *filter_udphdr(struct xdp_md *ctx, __u16 port)
 {
-	void *data_end = (void *)(long)ctx->data_end;
-	void *data = (void *)(long)ctx->data;
 	struct udphdr *udph = NULL;
-	struct ethhdr *eth = data;
+	void *data, *data_end;
+	struct ethhdr *eth;
+	int err;
+
+	err = bpf_xdp_pull_data(ctx, sizeof(*eth));
+	if (err)
+		return NULL;
+
+	data_end = (void *)(long)ctx->data_end;
+	data = eth = (void *)(long)ctx->data;
 
 	if (data + sizeof(*eth) > data_end)
 		return NULL;
 
 	if (eth->h_proto == bpf_htons(ETH_P_IP)) {
-		struct iphdr *iph = data + sizeof(*eth);
+		struct iphdr *iph;
+
+		err = bpf_xdp_pull_data(ctx, sizeof(*eth) + sizeof(*iph) +
+					     sizeof(*udph));
+		if (err)
+			return NULL;
+
+		data_end = (void *)(long)ctx->data_end;
+		data = (void *)(long)ctx->data;
+
+		iph = data + sizeof(*eth);
 
 		if (iph + 1 > (struct iphdr *)data_end ||
 		    iph->protocol != IPPROTO_UDP)
 			return NULL;
 
-		udph = (void *)eth + sizeof(*iph) + sizeof(*eth);
-	} else if (eth->h_proto  == bpf_htons(ETH_P_IPV6)) {
-		struct ipv6hdr *ipv6h = data + sizeof(*eth);
+		udph = data + sizeof(*iph) + sizeof(*eth);
+	} else if (eth->h_proto == bpf_htons(ETH_P_IPV6)) {
+		struct ipv6hdr *ipv6h;
+
+		err = bpf_xdp_pull_data(ctx, sizeof(*eth) + sizeof(*ipv6h) +
+					     sizeof(*udph));
+		if (err)
+			return NULL;
+
+		data_end = (void *)(long)ctx->data_end;
+		data = (void *)(long)ctx->data;
+
+		ipv6h = data + sizeof(*eth);
 
 		if (ipv6h + 1 > (struct ipv6hdr *)data_end ||
 		    ipv6h->nexthdr != IPPROTO_UDP)
 			return NULL;
 
-		udph = (void *)eth + sizeof(*ipv6h) + sizeof(*eth);
+		udph = data + sizeof(*ipv6h) + sizeof(*eth);
 	} else {
 		return NULL;
 	}
@@ -145,17 +174,34 @@ static void swap_machdr(void *data)
 
 static int xdp_mode_tx_handler(struct xdp_md *ctx, __u16 port)
 {
-	void *data_end = (void *)(long)ctx->data_end;
-	void *data = (void *)(long)ctx->data;
 	struct udphdr *udph = NULL;
-	struct ethhdr *eth = data;
+	void *data, *data_end;
+	struct ethhdr *eth;
+	int err;
+
+	err = bpf_xdp_pull_data(ctx, sizeof(*eth));
+	if (err)
+		return XDP_PASS;
+
+	data_end = (void *)(long)ctx->data_end;
+	data = eth = (void *)(long)ctx->data;
 
 	if (data + sizeof(*eth) > data_end)
 		return XDP_PASS;
 
 	if (eth->h_proto == bpf_htons(ETH_P_IP)) {
-		struct iphdr *iph = data + sizeof(*eth);
-		__be32 tmp_ip = iph->saddr;
+		struct iphdr *iph;
+		__be32 tmp_ip;
+
+		err = bpf_xdp_pull_data(ctx, sizeof(*eth) + sizeof(*iph) +
+					     sizeof(*udph));
+		if (err)
+			return XDP_PASS;
+
+		data_end = (void *)(long)ctx->data_end;
+		data = (void *)(long)ctx->data;
+
+		iph = data + sizeof(*eth);
 
 		if (iph + 1 > (struct iphdr *)data_end ||
 		    iph->protocol != IPPROTO_UDP)
@@ -169,8 +215,10 @@ static int xdp_mode_tx_handler(struct xdp_md *ctx, __u16 port)
 			return XDP_PASS;
 
 		record_stats(ctx, STATS_RX);
+		eth = data;
 		swap_machdr((void *)eth);
 
+		tmp_ip = iph->saddr;
 		iph->saddr = iph->daddr;
 		iph->daddr = tmp_ip;
 
@@ -178,9 +226,19 @@ static int xdp_mode_tx_handler(struct xdp_md *ctx, __u16 port)
 
 		return XDP_TX;
 
-	} else if (eth->h_proto  == bpf_htons(ETH_P_IPV6)) {
-		struct ipv6hdr *ipv6h = data + sizeof(*eth);
+	} else if (eth->h_proto == bpf_htons(ETH_P_IPV6)) {
 		struct in6_addr tmp_ipv6;
+		struct ipv6hdr *ipv6h;
+
+		err = bpf_xdp_pull_data(ctx, sizeof(*eth) + sizeof(*ipv6h) +
+					     sizeof(*udph));
+		if (err)
+			return XDP_PASS;
+
+		data_end = (void *)(long)ctx->data_end;
+		data = (void *)(long)ctx->data;
+
+		ipv6h = data + sizeof(*eth);
 
 		if (ipv6h + 1 > (struct ipv6hdr *)data_end ||
 		    ipv6h->nexthdr != IPPROTO_UDP)
@@ -194,6 +252,7 @@ static int xdp_mode_tx_handler(struct xdp_md *ctx, __u16 port)
 			return XDP_PASS;
 
 		record_stats(ctx, STATS_RX);
+		eth = data;
 		swap_machdr((void *)eth);
 
 		__builtin_memcpy(&tmp_ipv6, &ipv6h->saddr, sizeof(tmp_ipv6));