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ameryhungMartin KaFai Lau
ameryhung
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Martin KaFai Lau
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selftests/bpf: Test bpf_xdp_pull_data
Test bpf_xdp_pull_data() with xdp packets with different layouts. The xdp bpf program first checks if the layout is as expected. Then, it calls bpf_xdp_pull_data(). Finally, it checks the 0xbb marker at offset 1024 using directly packet access. Signed-off-by: Amery Hung <[email protected]> Signed-off-by: Martin KaFai Lau <[email protected]> Link: https://patch.msgid.link/[email protected]
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‎tools/testing/selftests/bpf/prog_tests/xdp_pull_data.c‎

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// SPDX-License-Identifier: GPL-2.0
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#include <test_progs.h>
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#include <network_helpers.h>
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#include "test_xdp_pull_data.skel.h"
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#define PULL_MAX (1 << 31)
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#define PULL_PLUS_ONE (1 << 30)
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#define XDP_PACKET_HEADROOM 256
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/* Find headroom and tailroom occupied by struct xdp_frame and struct
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* skb_shared_info so that we can calculate the maximum pull lengths for
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* test cases. They might not be the real size of the structures due to
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* cache alignment.
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*/
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static int find_xdp_sizes(struct test_xdp_pull_data *skel, int frame_sz)
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{
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LIBBPF_OPTS(bpf_test_run_opts, topts);
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struct xdp_md ctx = {};
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int prog_fd, err;
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__u8 *buf;
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buf = calloc(frame_sz, sizeof(__u8));
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if (!ASSERT_OK_PTR(buf, "calloc buf"))
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return -ENOMEM;
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topts.data_in = buf;
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topts.data_out = buf;
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topts.data_size_in = frame_sz;
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topts.data_size_out = frame_sz;
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/* Pass a data_end larger than the linear space available to make sure
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* bpf_prog_test_run_xdp() will fill the linear data area so that
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* xdp_find_sizes can infer the size of struct skb_shared_info
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*/
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ctx.data_end = frame_sz;
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topts.ctx_in = &ctx;
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topts.ctx_out = &ctx;
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topts.ctx_size_in = sizeof(ctx);
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topts.ctx_size_out = sizeof(ctx);
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prog_fd = bpf_program__fd(skel->progs.xdp_find_sizes);
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err = bpf_prog_test_run_opts(prog_fd, &topts);
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ASSERT_OK(err, "bpf_prog_test_run_opts");
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free(buf);
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return err;
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}
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/* xdp_pull_data_prog will directly read a marker 0xbb stored at buf[1024]
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* so caller expecting XDP_PASS should always pass pull_len no less than 1024
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*/
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static void run_test(struct test_xdp_pull_data *skel, int retval,
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int frame_sz, int buff_len, int meta_len, int data_len,
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int pull_len)
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{
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LIBBPF_OPTS(bpf_test_run_opts, topts);
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struct xdp_md ctx = {};
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int prog_fd, err;
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__u8 *buf;
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buf = calloc(buff_len, sizeof(__u8));
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if (!ASSERT_OK_PTR(buf, "calloc buf"))
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return;
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buf[meta_len + 1023] = 0xaa;
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buf[meta_len + 1024] = 0xbb;
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buf[meta_len + 1025] = 0xcc;
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topts.data_in = buf;
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topts.data_out = buf;
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topts.data_size_in = buff_len;
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topts.data_size_out = buff_len;
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ctx.data = meta_len;
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ctx.data_end = meta_len + data_len;
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topts.ctx_in = &ctx;
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topts.ctx_out = &ctx;
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topts.ctx_size_in = sizeof(ctx);
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topts.ctx_size_out = sizeof(ctx);
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skel->bss->data_len = data_len;
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if (pull_len & PULL_MAX) {
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int headroom = XDP_PACKET_HEADROOM - meta_len - skel->bss->xdpf_sz;
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int tailroom = frame_sz - XDP_PACKET_HEADROOM -
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data_len - skel->bss->sinfo_sz;
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pull_len = pull_len & PULL_PLUS_ONE ? 1 : 0;
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pull_len += headroom + tailroom + data_len;
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}
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skel->bss->pull_len = pull_len;
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prog_fd = bpf_program__fd(skel->progs.xdp_pull_data_prog);
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err = bpf_prog_test_run_opts(prog_fd, &topts);
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ASSERT_OK(err, "bpf_prog_test_run_opts");
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ASSERT_EQ(topts.retval, retval, "xdp_pull_data_prog retval");
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if (retval == XDP_DROP)
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goto out;
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ASSERT_EQ(ctx.data_end, meta_len + pull_len, "linear data size");
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ASSERT_EQ(topts.data_size_out, buff_len, "linear + non-linear data size");
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/* Make sure data around xdp->data_end was not messed up by
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* bpf_xdp_pull_data()
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*/
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ASSERT_EQ(buf[meta_len + 1023], 0xaa, "data[1023]");
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ASSERT_EQ(buf[meta_len + 1024], 0xbb, "data[1024]");
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ASSERT_EQ(buf[meta_len + 1025], 0xcc, "data[1025]");
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out:
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free(buf);
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}
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static void test_xdp_pull_data_basic(void)
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{
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u32 pg_sz, max_meta_len, max_data_len;
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struct test_xdp_pull_data *skel;
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skel = test_xdp_pull_data__open_and_load();
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if (!ASSERT_OK_PTR(skel, "test_xdp_pull_data__open_and_load"))
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return;
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pg_sz = sysconf(_SC_PAGE_SIZE);
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if (find_xdp_sizes(skel, pg_sz))
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goto out;
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max_meta_len = XDP_PACKET_HEADROOM - skel->bss->xdpf_sz;
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max_data_len = pg_sz - XDP_PACKET_HEADROOM - skel->bss->sinfo_sz;
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/* linear xdp pkt, pull 0 byte */
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run_test(skel, XDP_PASS, pg_sz, 2048, 0, 2048, 2048);
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/* multi-buf pkt, pull results in linear xdp pkt */
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run_test(skel, XDP_PASS, pg_sz, 2048, 0, 1024, 2048);
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/* multi-buf pkt, pull 1 byte to linear data area */
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run_test(skel, XDP_PASS, pg_sz, 9000, 0, 1024, 1025);
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/* multi-buf pkt, pull 0 byte to linear data area */
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run_test(skel, XDP_PASS, pg_sz, 9000, 0, 1025, 1025);
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/* multi-buf pkt, empty linear data area, pull requires memmove */
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run_test(skel, XDP_PASS, pg_sz, 9000, 0, 0, PULL_MAX);
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/* multi-buf pkt, no headroom */
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run_test(skel, XDP_PASS, pg_sz, 9000, max_meta_len, 1024, PULL_MAX);
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/* multi-buf pkt, no tailroom, pull requires memmove */
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run_test(skel, XDP_PASS, pg_sz, 9000, 0, max_data_len, PULL_MAX);
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/* Test cases with invalid pull length */
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/* linear xdp pkt, pull more than total data len */
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run_test(skel, XDP_DROP, pg_sz, 2048, 0, 2048, 2049);
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/* multi-buf pkt with no space left in linear data area */
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run_test(skel, XDP_DROP, pg_sz, 9000, max_meta_len, max_data_len,
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PULL_MAX | PULL_PLUS_ONE);
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/* multi-buf pkt, empty linear data area */
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run_test(skel, XDP_DROP, pg_sz, 9000, 0, 0, PULL_MAX | PULL_PLUS_ONE);
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/* multi-buf pkt, no headroom */
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run_test(skel, XDP_DROP, pg_sz, 9000, max_meta_len, 1024,
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PULL_MAX | PULL_PLUS_ONE);
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/* multi-buf pkt, no tailroom */
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run_test(skel, XDP_DROP, pg_sz, 9000, 0, max_data_len,
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PULL_MAX | PULL_PLUS_ONE);
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out:
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test_xdp_pull_data__destroy(skel);
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}
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void test_xdp_pull_data(void)
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{
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if (test__start_subtest("xdp_pull_data"))
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test_xdp_pull_data_basic();
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}

‎tools/testing/selftests/bpf/progs/test_xdp_pull_data.c‎

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// SPDX-License-Identifier: GPL-2.0
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#include "vmlinux.h"
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#include <bpf/bpf_helpers.h>
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int xdpf_sz;
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int sinfo_sz;
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int data_len;
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int pull_len;
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#define XDP_PACKET_HEADROOM 256
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SEC("xdp.frags")
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int xdp_find_sizes(struct xdp_md *ctx)
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{
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xdpf_sz = sizeof(struct xdp_frame);
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sinfo_sz = __PAGE_SIZE - XDP_PACKET_HEADROOM -
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(ctx->data_end - ctx->data);
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return XDP_PASS;
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}
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SEC("xdp.frags")
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int xdp_pull_data_prog(struct xdp_md *ctx)
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{
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__u8 *data_end = (void *)(long)ctx->data_end;
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__u8 *data = (void *)(long)ctx->data;
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__u8 *val_p;
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int err;
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if (data_len != data_end - data)
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return XDP_DROP;
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err = bpf_xdp_pull_data(ctx, pull_len);
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if (err)
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return XDP_DROP;
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val_p = (void *)(long)ctx->data + 1024;
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if (val_p + 1 > (void *)(long)ctx->data_end)
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return XDP_DROP;
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if (*val_p != 0xbb)
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return XDP_DROP;
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return XDP_PASS;
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}
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char _license[] SEC("license") = "GPL";

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