[PATCH bpf-next 02/10] [bpf]: adding tests for bpf_xdp_adjust_tail

Nikita V. Shirokov
2018-04-17T06:51:51Z

adding selftests for bpf_xdp_adjust_tail helper. in this syntetic 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.

aside from adding new tests i'm changing behaviour of bpf_prog_test_run
so it would recalculate packet's length if only data_end pointer was
changed

Signed-off-by: Nikita V. Shirokov <tehnerd@tehnerd.com>
---
net/bpf/test_run.c | 3 ++-
tools/include/uapi/linux/bpf.h | 11 ++++++++-
tools/testing/selftests/bpf/Makefile | 2 +-
tools/testing/selftests/bpf/bpf_helpers.h | 3 +++
tools/testing/selftests/bpf/test_adjust_tail.c | 29 +++++++++++++++++++++++
tools/testing/selftests/bpf/test_progs.c | 32 ++++++++++++++++++++++++++
6 files changed, 77 insertions(+), 3 deletions(-)
create mode 100644 tools/testing/selftests/bpf/test_adjust_tail.c

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 2ced48662c1f..68c3578343b4 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -170,7 +170,8 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
xdp.rxq = &rxqueue->xdp_rxq;

retval = bpf_test_run(prog, &xdp, repeat, &duration);
- if (xdp.data != data + XDP_PACKET_HEADROOM + NET_IP_ALIGN)
+ if (xdp.data != data + XDP_PACKET_HEADROOM + NET_IP_ALIGN ||
+ xdp.data_end != xdp.data + size)
size = xdp.data_end - xdp.data;
ret = bpf_test_finish(kattr, uattr, xdp.data, size, retval, duration);
kfree(data);
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 9d07465023a2..9a2d1a04eb24 100644
--- 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
@@ -864,6 +872,7 @@ enum bpf_func_id {
/* BPF_FUNC_skb_set_tunnel_key flags. */
#define BPF_F_ZERO_CSUM_TX (1ULL << 1)
#define BPF_F_DONT_FRAGMENT (1ULL << 2)
+#define BPF_F_SEQ_NUMBER (1ULL << 3)

/* BPF_FUNC_perf_event_output, BPF_FUNC_perf_event_read and
* BPF_FUNC_perf_event_read_value flags.
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 0a315ddabbf4..3e819dc70bee 100644
--- 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 d8223d99f96d..50c607014b22 100644
--- 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
index 000000000000..86239e792d6d
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_adjust_tail.c
@@ -0,0 +1,29 @@
+/* Copyright (c) 2016,2017 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 faadbe233966..eedda98d7bb1 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -166,6 +166,37 @@ static void test_xdp(void)
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();
--
2.15.1