From d831ee84bfc9173eecf30dbbc2553ae81b996c60 Mon Sep 17 00:00:00 2001 From: Eelco Chaudron Date: Fri, 6 Mar 2020 08:59:23 +0000 Subject: [PATCH] bpf: Add bpf_xdp_output() helper MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Introduce new helper that reuses existing xdp perf_event output implementation, but can be called from raw_tracepoint programs that receive 'struct xdp_buff *' as a tracepoint argument. Signed-off-by: Eelco Chaudron Signed-off-by: Alexei Starovoitov Acked-by: John Fastabend Acked-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/bpf/158348514556.2239.11050972434793741444.stgit@xdp-tutorial --- include/uapi/linux/bpf.h | 26 ++++++++- kernel/bpf/verifier.c | 4 +- kernel/trace/bpf_trace.c | 3 ++ net/core/filter.c | 16 +++++- tools/include/uapi/linux/bpf.h | 26 ++++++++- .../selftests/bpf/prog_tests/xdp_bpf2bpf.c | 53 +++++++++++++++++++ .../selftests/bpf/progs/test_xdp_bpf2bpf.c | 24 +++++++++ 7 files changed, 148 insertions(+), 4 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 15b239da775b..5d01c5c7e598 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2927,6 +2927,29 @@ union bpf_attr { * * **-ENOENT** if pidns does not exists for the current task. * + * int bpf_xdp_output(void *ctx, struct bpf_map *map, u64 flags, void *data, u64 size) + * Description + * Write raw *data* blob into a special BPF perf event held by + * *map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf + * event must have the following attributes: **PERF_SAMPLE_RAW** + * as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and + * **PERF_COUNT_SW_BPF_OUTPUT** as **config**. + * + * The *flags* are used to indicate the index in *map* for which + * the value must be put, masked with **BPF_F_INDEX_MASK**. + * Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU** + * to indicate that the index of the current CPU core should be + * used. + * + * The value to write, of *size*, is passed through eBPF stack and + * pointed by *data*. + * + * *ctx* is a pointer to in-kernel struct xdp_buff. + * + * This helper is similar to **bpf_perf_eventoutput**\ () but + * restricted to raw_tracepoint bpf programs. + * Return + * 0 on success, or a negative error in case of failure. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3049,7 +3072,8 @@ union bpf_attr { FN(send_signal_thread), \ FN(jiffies64), \ FN(read_branch_records), \ - FN(get_ns_current_pid_tgid), + FN(get_ns_current_pid_tgid), \ + FN(xdp_output), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 55d376c53f7d..745f3cfdf3b2 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3650,7 +3650,8 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, if (func_id != BPF_FUNC_perf_event_read && func_id != BPF_FUNC_perf_event_output && func_id != BPF_FUNC_skb_output && - func_id != BPF_FUNC_perf_event_read_value) + func_id != BPF_FUNC_perf_event_read_value && + func_id != BPF_FUNC_xdp_output) goto error; break; case BPF_MAP_TYPE_STACK_TRACE: @@ -3740,6 +3741,7 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env, case BPF_FUNC_perf_event_output: case BPF_FUNC_perf_event_read_value: case BPF_FUNC_skb_output: + case BPF_FUNC_xdp_output: if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) goto error; break; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index b5071c7e93ca..e619eedb5919 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1145,6 +1145,7 @@ static const struct bpf_func_proto bpf_perf_event_output_proto_raw_tp = { }; extern const struct bpf_func_proto bpf_skb_output_proto; +extern const struct bpf_func_proto bpf_xdp_output_proto; BPF_CALL_3(bpf_get_stackid_raw_tp, struct bpf_raw_tracepoint_args *, args, struct bpf_map *, map, u64, flags) @@ -1220,6 +1221,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) #ifdef CONFIG_NET case BPF_FUNC_skb_output: return &bpf_skb_output_proto; + case BPF_FUNC_xdp_output: + return &bpf_xdp_output_proto; #endif default: return raw_tp_prog_func_proto(func_id, prog); diff --git a/net/core/filter.c b/net/core/filter.c index cd0a532db4e7..22219544410f 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -4061,7 +4061,8 @@ BPF_CALL_5(bpf_xdp_event_output, struct xdp_buff *, xdp, struct bpf_map *, map, if (unlikely(flags & ~(BPF_F_CTXLEN_MASK | BPF_F_INDEX_MASK))) return -EINVAL; - if (unlikely(xdp_size > (unsigned long)(xdp->data_end - xdp->data))) + if (unlikely(!xdp || + xdp_size > (unsigned long)(xdp->data_end - xdp->data))) return -EFAULT; return bpf_event_output(map, flags, meta, meta_size, xdp->data, @@ -4079,6 +4080,19 @@ static const struct bpf_func_proto bpf_xdp_event_output_proto = { .arg5_type = ARG_CONST_SIZE_OR_ZERO, }; +static int bpf_xdp_output_btf_ids[5]; +const struct bpf_func_proto bpf_xdp_output_proto = { + .func = bpf_xdp_event_output, + .gpl_only = true, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_BTF_ID, + .arg2_type = ARG_CONST_MAP_PTR, + .arg3_type = ARG_ANYTHING, + .arg4_type = ARG_PTR_TO_MEM, + .arg5_type = ARG_CONST_SIZE_OR_ZERO, + .btf_id = bpf_xdp_output_btf_ids, +}; + BPF_CALL_1(bpf_get_socket_cookie, struct sk_buff *, skb) { return skb->sk ? sock_gen_cookie(skb->sk) : 0; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 15b239da775b..5d01c5c7e598 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -2927,6 +2927,29 @@ union bpf_attr { * * **-ENOENT** if pidns does not exists for the current task. * + * int bpf_xdp_output(void *ctx, struct bpf_map *map, u64 flags, void *data, u64 size) + * Description + * Write raw *data* blob into a special BPF perf event held by + * *map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf + * event must have the following attributes: **PERF_SAMPLE_RAW** + * as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and + * **PERF_COUNT_SW_BPF_OUTPUT** as **config**. + * + * The *flags* are used to indicate the index in *map* for which + * the value must be put, masked with **BPF_F_INDEX_MASK**. + * Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU** + * to indicate that the index of the current CPU core should be + * used. + * + * The value to write, of *size*, is passed through eBPF stack and + * pointed by *data*. + * + * *ctx* is a pointer to in-kernel struct xdp_buff. + * + * This helper is similar to **bpf_perf_eventoutput**\ () but + * restricted to raw_tracepoint bpf programs. + * Return + * 0 on success, or a negative error in case of failure. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3049,7 +3072,8 @@ union bpf_attr { FN(send_signal_thread), \ FN(jiffies64), \ FN(read_branch_records), \ - FN(get_ns_current_pid_tgid), + FN(get_ns_current_pid_tgid), \ + FN(xdp_output), /* 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/prog_tests/xdp_bpf2bpf.c b/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c index 4ba011031d4c..a0f688c37023 100644 --- a/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c +++ b/tools/testing/selftests/bpf/prog_tests/xdp_bpf2bpf.c @@ -4,17 +4,51 @@ #include "test_xdp.skel.h" #include "test_xdp_bpf2bpf.skel.h" +struct meta { + int ifindex; + int pkt_len; +}; + +static void on_sample(void *ctx, int cpu, void *data, __u32 size) +{ + int duration = 0; + struct meta *meta = (struct meta *)data; + struct ipv4_packet *trace_pkt_v4 = data + sizeof(*meta); + + if (CHECK(size < sizeof(pkt_v4) + sizeof(*meta), + "check_size", "size %u < %zu\n", + size, sizeof(pkt_v4) + sizeof(*meta))) + return; + + if (CHECK(meta->ifindex != if_nametoindex("lo"), "check_meta_ifindex", + "meta->ifindex = %d\n", meta->ifindex)) + return; + + if (CHECK(meta->pkt_len != sizeof(pkt_v4), "check_meta_pkt_len", + "meta->pkt_len = %zd\n", sizeof(pkt_v4))) + return; + + if (CHECK(memcmp(trace_pkt_v4, &pkt_v4, sizeof(pkt_v4)), + "check_packet_content", "content not the same\n")) + return; + + *(bool *)ctx = true; +} + void test_xdp_bpf2bpf(void) { __u32 duration = 0, retval, size; char buf[128]; int err, pkt_fd, map_fd; + bool passed = false; struct iphdr *iph = (void *)buf + sizeof(struct ethhdr); struct iptnl_info value4 = {.family = AF_INET}; struct test_xdp *pkt_skel = NULL; struct test_xdp_bpf2bpf *ftrace_skel = NULL; struct vip key4 = {.protocol = 6, .family = AF_INET}; struct bpf_program *prog; + struct perf_buffer *pb = NULL; + struct perf_buffer_opts pb_opts = {}; /* Load XDP program to introspect */ pkt_skel = test_xdp__open_and_load(); @@ -50,6 +84,14 @@ void test_xdp_bpf2bpf(void) if (CHECK(err, "ftrace_attach", "ftrace attach failed: %d\n", err)) goto out; + /* Set up perf buffer */ + pb_opts.sample_cb = on_sample; + pb_opts.ctx = &passed; + pb = perf_buffer__new(bpf_map__fd(ftrace_skel->maps.perf_buf_map), + 1, &pb_opts); + if (CHECK(IS_ERR(pb), "perf_buf__new", "err %ld\n", PTR_ERR(pb))) + goto out; + /* Run test program */ err = bpf_prog_test_run(pkt_fd, 1, &pkt_v4, sizeof(pkt_v4), buf, &size, &retval, &duration); @@ -60,6 +102,15 @@ void test_xdp_bpf2bpf(void) err, errno, retval, size)) goto out; + /* Make sure bpf_xdp_output() was triggered and it sent the expected + * data to the perf ring buffer. + */ + err = perf_buffer__poll(pb, 100); + if (CHECK(err < 0, "perf_buffer__poll", "err %d\n", err)) + goto out; + + CHECK_FAIL(!passed); + /* Verify test results */ if (CHECK(ftrace_skel->bss->test_result_fentry != if_nametoindex("lo"), "result", "fentry failed err %llu\n", @@ -70,6 +121,8 @@ void test_xdp_bpf2bpf(void) "fexit failed err %llu\n", ftrace_skel->bss->test_result_fexit); out: + if (pb) + perf_buffer__free(pb); test_xdp__destroy(pkt_skel); test_xdp_bpf2bpf__destroy(ftrace_skel); } diff --git a/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c b/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c index 42dd2fedd588..a038e827f850 100644 --- a/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c +++ b/tools/testing/selftests/bpf/progs/test_xdp_bpf2bpf.c @@ -3,6 +3,8 @@ #include #include +char _license[] SEC("license") = "GPL"; + struct net_device { /* Structure does not need to contain all entries, * as "preserve_access_index" will use BTF to fix this... @@ -27,10 +29,32 @@ struct xdp_buff { struct xdp_rxq_info *rxq; } __attribute__((preserve_access_index)); +struct meta { + int ifindex; + int pkt_len; +}; + +struct { + __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY); + __uint(key_size, sizeof(int)); + __uint(value_size, sizeof(int)); +} perf_buf_map SEC(".maps"); + __u64 test_result_fentry = 0; SEC("fentry/FUNC") int BPF_PROG(trace_on_entry, struct xdp_buff *xdp) { + struct meta meta; + void *data_end = (void *)(long)xdp->data_end; + void *data = (void *)(long)xdp->data; + + meta.ifindex = xdp->rxq->dev->ifindex; + meta.pkt_len = data_end - data; + bpf_xdp_output(xdp, &perf_buf_map, + ((__u64) meta.pkt_len << 32) | + BPF_F_CURRENT_CPU, + &meta, sizeof(meta)); + test_result_fentry = xdp->rxq->dev->ifindex; return 0; } -- 2.39.5