diff options
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/kfree_skb.c | 89 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/kfree_skb.c | 103 |
2 files changed, 192 insertions, 0 deletions
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..430b50de1583 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/kfree_skb.c @@ -0,0 +1,89 @@ +// 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 %u != 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", + }; + + 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, "tp_btf/kfree_skb"); + if (CHECK(!prog, "find_prog", "prog kfree_skb not found\n")) + goto close_prog; + link = bpf_program__attach_raw_tracepoint(prog, NULL); + 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..89af8a921ee4 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/kfree_skb.c @@ -0,0 +1,103 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (c) 2019 Facebook +#include <linux/bpf.h> +#include "bpf_helpers.h" +#include "bpf_endian.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; + struct dev_ifalias *ifalias; +}; + +typedef struct { + int counter; +} atomic_t; +typedef struct refcount_struct { + atomic_t refs; +} refcount_t; + +struct sk_buff { + /* field names and sizes should match to those in the kernel */ + unsigned int len, data_len; + __u16 mac_len, hdr_len, queue_mapping; + struct net_device *dev; + /* order of the fields doesn't matter */ + refcount_t users; + unsigned char *data; + char __pkt_type_offset[0]; +}; + +/* 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("tp_btf/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; + int users; + unsigned char *data; + unsigned short pkt_data; + char pkt_type; + + __builtin_preserve_access_index(({ + users = skb->users.refs.counter; + data = skb->data; + dev = skb->dev; + ifindex = dev->ifindex; + ptr = dev->ifalias->rcuhead.next; + func = ptr->func; + })); + + bpf_probe_read(&pkt_type, sizeof(pkt_type), _(&skb->__pkt_type_offset)); + pkt_type &= 7; + + /* read eth proto */ + bpf_probe_read(&pkt_data, sizeof(pkt_data), data + 12); + + bpf_printk("rcuhead.next %llx func %llx\n", ptr, func); + bpf_printk("skb->len %d users %d pkt_type %x\n", + _(skb->len), users, pkt_type); + bpf_printk("skb->queue_mapping %d\n", _(skb->queue_mapping)); + bpf_printk("dev->ifindex %d data %llx pkt_data %x\n", + ifindex, data, pkt_data); + + if (users != 1 || pkt_data != bpf_htons(0x86dd) || ifindex != 1) + /* raw tp ignores return value */ + return 0; + + /* 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; +} |