6.17-stable review patch. If anyone has any objections, please let me know.
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From: Amery Hung ameryhung@gmail.com
[ Upstream commit efec2e55bdefb889639a6e7fe1f1f2431cdddc6a ]
It is possible for drivers to generate xdp packets with data residing entirely in fragments. To keep parsing headers using direct packet access, call bpf_xdp_pull_data() to pull headers into the linear data area.
Signed-off-by: Amery Hung ameryhung@gmail.com Signed-off-by: Martin KaFai Lau martin.lau@kernel.org Link: https://patch.msgid.link/20250922233356.3356453-9-ameryhung@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- .../selftests/net/lib/xdp_native.bpf.c | 89 +++++++++++++++---- 1 file 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 521ba38f2ddda..df4eea5c192b3 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));