[RFC bpf-next v1 7/7] selftests: drv-net: Pull data before parsing headers
From: Amery Hung <hidden>
Date: 2025-08-25 19:39:29
Also in:
bpf
Subsystem:
kernel selftest framework, networking [general], the rest · Maintainers:
Shuah Khan, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
It is possible for drivers to generate xdp packets with data residing entirely in fragments. To keep parsing headers using direcy packet access, call bpf_xdp_pull_data() to pull headers into the linear data area. Signed-off-by: Amery Hung <redacted> --- .../selftests/net/lib/xdp_native.bpf.c | 90 +++++++++++++++---- 1 file changed, 75 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..68b2a08055ce 100644
--- a/tools/testing/selftests/net/lib/xdp_native.bpf.c
+++ b/tools/testing/selftests/net/lib/xdp_native.bpf.c@@ -14,6 +14,9 @@ #define MAX_PAYLOAD_LEN 5000 #define MAX_HDR_LEN 64 +extern int bpf_xdp_pull_data(struct xdp_md *xdp, __u32 len, + __u64 flags) __ksym __weak; + enum { XDP_MODE = 0, XDP_PORT = 1,
@@ -68,30 +71,57 @@ 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), 0); + 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), 0); + 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), 0); + 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 +175,34 @@ 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), 0); + 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), 0); + 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 +216,10 @@ 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 +227,19 @@ 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), 0); + 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 +253,7 @@ 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));
--
2.47.3