Load basic cls_bpf program.
Load raw_tracepoint program and attach to kfree_skb raw tracepoint.
Trigger cls_bpf via prog_test_run.
At the end of test_run kernel will call kfree_skb
which will trigger trace_kfree_skb tracepoint.
Which will call our raw_tracepoint program.
Which will take that skb and will dump it into perf ring buffer.
Check that user space received correct packet.
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
---
.../selftests/bpf/prog_tests/kfree_skb.c | 90 +++++++++++++++++++
tools/testing/selftests/bpf/progs/kfree_skb.c | 76 ++++++++++++++++
2 files changed, 166 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/kfree_skb.c
create mode 100644 tools/testing/selftests/bpf/progs/kfree_skb.c
diff --git a/tools/testing/selftests/bpf/prog_tests/kfree_skb.c b/tools/testing/selftests/bpf/prog_tests/kfree_skb.c
new file mode 100644
index 000000000000..238bc7024b36
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/kfree_skb.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+
+static void on_sample(void *ctx, int cpu, void *data, __u32 size)
+{
+ int ifindex = *(int *)data, duration = 0;
+ struct ipv6_packet * pkt_v6 = data + 4;
+
+ if (ifindex != 1)
+ /* spurious kfree_skb not on loopback device */
+ return;
+ if (CHECK(size != 76, "check_size", "size %d != 76\n", size))
+ return;
+ if (CHECK(pkt_v6->eth.h_proto != 0xdd86, "check_eth",
+ "h_proto %x\n", pkt_v6->eth.h_proto))
+ return;
+ if (CHECK(pkt_v6->iph.nexthdr != 6, "check_ip",
+ "iph.nexthdr %x\n", pkt_v6->iph.nexthdr))
+ return;
+ if (CHECK(pkt_v6->tcp.doff != 5, "check_tcp",
+ "tcp.doff %x\n", pkt_v6->tcp.doff))
+ return;
+
+ *(bool *)ctx = true;
+}
+
+void test_kfree_skb(void)
+{
+ struct bpf_prog_load_attr attr = {
+ .file = "./kfree_skb.o",
+ .log_level = 2,
+ };
+
+ struct bpf_object *obj, *obj2 = NULL;
+ struct perf_buffer_opts pb_opts = {};
+ struct perf_buffer *pb = NULL;
+ struct bpf_link *link = NULL;
+ struct bpf_map *perf_buf_map;
+ struct bpf_program *prog;
+ __u32 duration, retval;
+ int err, pkt_fd, kfree_skb_fd;
+ bool passed = false;
+
+ err = bpf_prog_load("./test_pkt_access.o", BPF_PROG_TYPE_SCHED_CLS, &obj, &pkt_fd);
+ if (CHECK(err, "prog_load sched cls", "err %d errno %d\n", err, errno))
+ return;
+
+ err = bpf_prog_load_xattr(&attr, &obj2, &kfree_skb_fd);
+ if (CHECK(err, "prog_load raw tp", "err %d errno %d\n", err, errno))
+ goto close_prog;
+
+ prog = bpf_object__find_program_by_title(obj2, "raw_tracepoint/kfree_skb");
+ if (CHECK(!prog, "find_prog", "prog kfree_skb not found\n"))
+ goto close_prog;
+ link = bpf_program__attach_raw_tracepoint(prog, "kfree_skb");
+ if (CHECK(IS_ERR(link), "attach_raw_tp", "err %ld\n", PTR_ERR(link)))
+ goto close_prog;
+
+ perf_buf_map = bpf_object__find_map_by_name(obj2, "perf_buf_map");
+ if (CHECK(!perf_buf_map, "find_perf_buf_map", "not found\n"))
+ goto close_prog;
+
+ /* set up perf buffer */
+ pb_opts.sample_cb = on_sample;
+ pb_opts.ctx = &passed;
+ pb = perf_buffer__new(bpf_map__fd(perf_buf_map), 1, &pb_opts);
+ if (CHECK(IS_ERR(pb), "perf_buf__new", "err %ld\n", PTR_ERR(pb)))
+ goto close_prog;
+
+ err = bpf_prog_test_run(pkt_fd, 1, &pkt_v6, sizeof(pkt_v6),
+ NULL, NULL, &retval, &duration);
+ CHECK(err || retval, "ipv6",
+ "err %d errno %d retval %d duration %d\n",
+ err, errno, retval, duration);
+
+ /* read perf buffer */
+ err = perf_buffer__poll(pb, 100);
+ if (CHECK(err < 0, "perf_buffer__poll", "err %d\n", err))
+ goto close_prog;
+ /* make sure kfree_skb program was triggered
+ * and it sent expected skb into ring buffer
+ */
+ CHECK_FAIL(!passed);
+close_prog:
+ perf_buffer__free(pb);
+ if (!IS_ERR_OR_NULL(link))
+ bpf_link__destroy(link);
+ bpf_object__close(obj);
+ bpf_object__close(obj2);
+}
diff --git a/tools/testing/selftests/bpf/progs/kfree_skb.c b/tools/testing/selftests/bpf/progs/kfree_skb.c
new file mode 100644
index 000000000000..61f1abfc4f48
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/kfree_skb.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2019 Facebook
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+char _license[] SEC("license") = "GPL";
+struct {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __uint(key_size, sizeof(int));
+ __uint(value_size, sizeof(int));
+} perf_buf_map SEC(".maps");
+
+#define _(P) (__builtin_preserve_access_index(P))
+
+/* define few struct-s that bpf program needs to access */
+struct callback_head {
+ struct callback_head *next;
+ void (*func)(struct callback_head *head);
+};
+struct dev_ifalias {
+ struct callback_head rcuhead;
+};
+
+struct net_device /* same as kernel's struct net_device */ {
+ int ifindex;
+ volatile struct dev_ifalias *ifalias;
+};
+
+struct sk_buff {
+ /* field names and sizes should match to those in the kernel */
+ unsigned int len,
+ data_len;
+ __u16 mac_len,
+ hdr_len;
+ __u16 queue_mapping;
+ struct net_device *dev;
+ /* order of the fields doesn't matter */
+};
+
+/* copy arguments from
+ * include/trace/events/skb.h:
+ * TRACE_EVENT(kfree_skb,
+ * TP_PROTO(struct sk_buff *skb, void *location),
+ *
+ * into struct below:
+ */
+struct trace_kfree_skb {
+ struct sk_buff *skb;
+ void *location;
+};
+
+SEC("raw_tracepoint/kfree_skb")
+int trace_kfree_skb(struct trace_kfree_skb* ctx)
+{
+ struct sk_buff *skb = ctx->skb;
+ struct net_device *dev;
+ int ifindex;
+ struct callback_head *ptr;
+ void *func;
+ __builtin_preserve_access_index(({
+ dev = skb->dev;
+ ifindex = dev->ifindex;
+ ptr = dev->ifalias->rcuhead.next;
+ func = ptr->func;
+ }));
+
+ bpf_printk("rcuhead.next %llx func %llx\n", ptr, func);
+ bpf_printk("skb->len %d\n", _(skb->len));
+ bpf_printk("skb->queue_mapping %d\n", _(skb->queue_mapping));
+ bpf_printk("dev->ifindex %d\n", ifindex);
+
+ /* send first 72 byte of the packet to user space */
+ bpf_skb_output(skb, &perf_buf_map, (72ull << 32) | BPF_F_CURRENT_CPU,
+ &ifindex, sizeof(ifindex));
+ return 0;
+}
--
2.20.0
