bpf: adding tests for bpf_xdp_adjust_tail

adding selftests for bpf_xdp_adjust_tail helper. in this synthetic test
we are testing that 1) if data_end < data helper will return EINVAL
2) for normal use case packet's length would be reduced.

Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 9d07465..56bf493 100644 (file)
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -755,6 +755,13 @@ union bpf_attr {
  *     @addr: pointer to struct sockaddr to bind socket to
  *     @addr_len: length of sockaddr structure
  *     Return: 0 on success or negative error code
+ *
+ * int bpf_xdp_adjust_tail(xdp_md, delta)
+ *     Adjust the xdp_md.data_end by delta. Only shrinking of packet's
+ *     size is supported.
+ *     @xdp_md: pointer to xdp_md
+ *     @delta: A negative integer to be added to xdp_md.data_end
+ *     Return: 0 on success or negative on error
  */
 #define __BPF_FUNC_MAPPER(FN)          \
        FN(unspec),                     \
@@ -821,7 +828,8 @@ union bpf_attr {
        FN(msg_apply_bytes),            \
        FN(msg_cork_bytes),             \
        FN(msg_pull_data),              \
-       FN(bind),
+       FN(bind),                       \
+       FN(xdp_adjust_tail),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 0a315dd..3e819dc 100644 (file)
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -31,7 +31,7 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test
        sockmap_verdict_prog.o dev_cgroup.o sample_ret0.o test_tracepoint.o \
        test_l4lb_noinline.o test_xdp_noinline.o test_stacktrace_map.o \
        sample_map_ret0.o test_tcpbpf_kern.o test_stacktrace_build_id.o \
-       sockmap_tcp_msg_prog.o connect4_prog.o connect6_prog.o
+       sockmap_tcp_msg_prog.o connect4_prog.o connect6_prog.o test_adjust_tail.o
 
 # Order correspond to 'make run_tests' order
 TEST_PROGS := test_kmod.sh \

diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index d8223d9..50c6070 100644 (file)
--- a/tools/testing/selftests/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h
@@ -96,6 +96,9 @@ static int (*bpf_msg_pull_data)(void *ctx, int start, int end, int flags) =
        (void *) BPF_FUNC_msg_pull_data;
 static int (*bpf_bind)(void *ctx, void *addr, int addr_len) =
        (void *) BPF_FUNC_bind;
+static int (*bpf_xdp_adjust_tail)(void *ctx, int offset) =
+       (void *) BPF_FUNC_xdp_adjust_tail;
+
 
 /* llvm builtin functions that eBPF C program may use to
  * emit BPF_LD_ABS and BPF_LD_IND instructions

diff --git a/tools/testing/selftests/bpf/test_adjust_tail.c b/tools/testing/selftests/bpf/test_adjust_tail.c
new file mode 100644 (file)
index 0000000..4cd5e86
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_adjust_tail.c
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0
+ * Copyright (c) 2018 Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#include <linux/bpf.h>
+#include <linux/if_ether.h>
+#include "bpf_helpers.h"
+
+int _version SEC("version") = 1;
+
+SEC("xdp_adjust_tail")
+int _xdp_adjust_tail(struct xdp_md *xdp)
+{
+       void *data_end = (void *)(long)xdp->data_end;
+       void *data = (void *)(long)xdp->data;
+       int offset = 0;
+
+       if (data_end - data == 54)
+               offset = 256;
+       else
+               offset = 20;
+       if (bpf_xdp_adjust_tail(xdp, 0 - offset))
+               return XDP_DROP;
+       return XDP_TX;
+}
+
+char _license[] SEC("license") = "GPL";

diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index faadbe2..eedda98 100644 (file)
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -166,6 +166,37 @@ out:
        bpf_object__close(obj);
 }
 
+static void test_xdp_adjust_tail(void)
+{
+       const char *file = "./test_adjust_tail.o";
+       struct bpf_object *obj;
+       char buf[128];
+       __u32 duration, retval, size;
+       int err, prog_fd;
+
+       err = bpf_prog_load(file, BPF_PROG_TYPE_XDP, &obj, &prog_fd);
+       if (err) {
+               error_cnt++;
+               return;
+       }
+
+       err = bpf_prog_test_run(prog_fd, 1, &pkt_v4, sizeof(pkt_v4),
+                               buf, &size, &retval, &duration);
+
+       CHECK(err || errno || retval != XDP_DROP,
+             "ipv4", "err %d errno %d retval %d size %d\n",
+             err, errno, retval, size);
+
+       err = bpf_prog_test_run(prog_fd, 1, &pkt_v6, sizeof(pkt_v6),
+                               buf, &size, &retval, &duration);
+       CHECK(err || errno || retval != XDP_TX || size != 54,
+             "ipv6", "err %d errno %d retval %d size %d\n",
+             err, errno, retval, size);
+       bpf_object__close(obj);
+}
+
+
+
 #define MAGIC_VAL 0x1234
 #define NUM_ITER 100000
 #define VIP_NUM 5
@@ -1177,6 +1208,7 @@ int main(void)
 {
        test_pkt_access();
        test_xdp();
+       test_xdp_adjust_tail();
        test_l4lb_all();
        test_xdp_noinline();
        test_tcp_estats();