bpf: Add bpf_xdp_output() helper

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 <echaudro@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/158348514556.2239.11050972434793741444.stgit@xdp-tutorial
This commit is contained in:
Eelco Chaudron 2020-03-06 08:59:23 +00:00 committed by Alexei Starovoitov
parent 4823b7210b
commit d831ee84bf
7 changed files with 148 additions and 4 deletions

View File

@ -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

View File

@ -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;

View File

@ -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);

View File

@ -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;

View File

@ -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

View File

@ -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);
}

View File

@ -3,6 +3,8 @@
#include <bpf/bpf_tracing.h>
#include <bpf/bpf_helpers.h>
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;
}