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Merge branch 'bpf-xdp-add-tracepoint-to-xdp-attaching-failure'
Leon Hwang says: ==================== bpf, xdp: Add tracepoint to xdp attaching failure This series introduces a new tracepoint in bpf_xdp_link_attach(). By this tracepoint, error message will be captured when error happens in dev_xdp_attach(), e.g. invalid attaching flags. v4 -> v5: * Initialise the extack variable. * Fix code style issue of variable declaration lines. v3 -> v4: * Fix selftest-crashed issue. ==================== Link: https://lore.kernel.org/r/20230801142621.7925-1-hffilwlqm@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
commit
87dc2bb329
4 changed files with 140 additions and 1 deletions
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@ -404,6 +404,23 @@ TRACE_EVENT(mem_return_failed,
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)
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);
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TRACE_EVENT(bpf_xdp_link_attach_failed,
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TP_PROTO(const char *msg),
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TP_ARGS(msg),
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TP_STRUCT__entry(
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__string(msg, msg)
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),
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TP_fast_assign(
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__assign_str(msg, msg);
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),
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TP_printk("errmsg=%s", __get_str(msg))
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);
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#endif /* _TRACE_XDP_H */
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#include <trace/define_trace.h>
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@ -133,6 +133,7 @@
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#include <trace/events/net.h>
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#include <trace/events/skb.h>
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#include <trace/events/qdisc.h>
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#include <trace/events/xdp.h>
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#include <linux/inetdevice.h>
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#include <linux/cpu_rmap.h>
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#include <linux/static_key.h>
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@ -9470,6 +9471,7 @@ int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
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{
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struct net *net = current->nsproxy->net_ns;
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struct bpf_link_primer link_primer;
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struct netlink_ext_ack extack = {};
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struct bpf_xdp_link *link;
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struct net_device *dev;
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int err, fd;
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@ -9497,12 +9499,13 @@ int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
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goto unlock;
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}
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err = dev_xdp_attach_link(dev, NULL, link);
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err = dev_xdp_attach_link(dev, &extack, link);
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rtnl_unlock();
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if (err) {
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link->dev = NULL;
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bpf_link_cleanup(&link_primer);
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trace_bpf_xdp_link_attach_failed(extack._msg);
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goto out_put_dev;
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}
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@ -1,5 +1,6 @@
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// SPDX-License-Identifier: GPL-2.0
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#include <test_progs.h>
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#include "test_xdp_attach_fail.skel.h"
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#define IFINDEX_LO 1
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#define XDP_FLAGS_REPLACE (1U << 4)
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@ -85,10 +86,74 @@ out_1:
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bpf_object__close(obj1);
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}
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#define ERRMSG_LEN 64
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struct xdp_errmsg {
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char msg[ERRMSG_LEN];
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};
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static void on_xdp_errmsg(void *ctx, int cpu, void *data, __u32 size)
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{
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struct xdp_errmsg *ctx_errmg = ctx, *tp_errmsg = data;
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memcpy(&ctx_errmg->msg, &tp_errmsg->msg, ERRMSG_LEN);
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}
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static const char tgt_errmsg[] = "Invalid XDP flags for BPF link attachment";
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static void test_xdp_attach_fail(const char *file)
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{
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struct test_xdp_attach_fail *skel = NULL;
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struct xdp_errmsg errmsg = {};
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struct perf_buffer *pb = NULL;
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struct bpf_object *obj = NULL;
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int err, fd_xdp;
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LIBBPF_OPTS(bpf_link_create_opts, opts);
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skel = test_xdp_attach_fail__open_and_load();
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if (!ASSERT_OK_PTR(skel, "test_xdp_attach_fail__open_and_load"))
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goto out_close;
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err = test_xdp_attach_fail__attach(skel);
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if (!ASSERT_EQ(err, 0, "test_xdp_attach_fail__attach"))
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goto out_close;
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/* set up perf buffer */
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pb = perf_buffer__new(bpf_map__fd(skel->maps.xdp_errmsg_pb), 1,
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on_xdp_errmsg, NULL, &errmsg, NULL);
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if (!ASSERT_OK_PTR(pb, "perf_buffer__new"))
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goto out_close;
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err = bpf_prog_test_load(file, BPF_PROG_TYPE_XDP, &obj, &fd_xdp);
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if (!ASSERT_EQ(err, 0, "bpf_prog_test_load"))
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goto out_close;
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opts.flags = 0xFF; // invalid flags to fail to attach XDP prog
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err = bpf_link_create(fd_xdp, IFINDEX_LO, BPF_XDP, &opts);
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if (!ASSERT_EQ(err, -EINVAL, "bpf_link_create"))
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goto out_close;
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/* read perf buffer */
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err = perf_buffer__poll(pb, 100);
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if (!ASSERT_GT(err, -1, "perf_buffer__poll"))
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goto out_close;
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ASSERT_STRNEQ((const char *) errmsg.msg, tgt_errmsg,
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42 /* strlen(tgt_errmsg) */, "check error message");
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out_close:
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perf_buffer__free(pb);
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bpf_object__close(obj);
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test_xdp_attach_fail__destroy(skel);
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}
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void serial_test_xdp_attach(void)
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{
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if (test__start_subtest("xdp_attach"))
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test_xdp_attach("./test_xdp.bpf.o");
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if (test__start_subtest("xdp_attach_dynptr"))
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test_xdp_attach("./test_xdp_dynptr.bpf.o");
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if (test__start_subtest("xdp_attach_failed"))
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test_xdp_attach_fail("./xdp_dummy.bpf.o");
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}
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54
tools/testing/selftests/bpf/progs/test_xdp_attach_fail.c
Normal file
54
tools/testing/selftests/bpf/progs/test_xdp_attach_fail.c
Normal file
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@ -0,0 +1,54 @@
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright Leon Hwang */
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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#define ERRMSG_LEN 64
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struct xdp_errmsg {
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char msg[ERRMSG_LEN];
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};
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struct {
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__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
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__type(key, int);
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__type(value, int);
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} xdp_errmsg_pb SEC(".maps");
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struct xdp_attach_error_ctx {
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unsigned long unused;
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/*
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* bpf does not support tracepoint __data_loc directly.
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*
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* Actually, this field is a 32 bit integer whose value encodes
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* information on where to find the actual data. The first 2 bytes is
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* the size of the data. The last 2 bytes is the offset from the start
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* of the tracepoint struct where the data begins.
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* -- https://github.com/iovisor/bpftrace/pull/1542
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*/
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__u32 msg; // __data_loc char[] msg;
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};
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/*
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* Catch the error message at the tracepoint.
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*/
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SEC("tp/xdp/bpf_xdp_link_attach_failed")
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int tp__xdp__bpf_xdp_link_attach_failed(struct xdp_attach_error_ctx *ctx)
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{
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char *msg = (void *)(__u64) ((void *) ctx + (__u16) ctx->msg);
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struct xdp_errmsg errmsg = {};
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bpf_probe_read_kernel_str(&errmsg.msg, ERRMSG_LEN, msg);
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bpf_perf_event_output(ctx, &xdp_errmsg_pb, BPF_F_CURRENT_CPU, &errmsg,
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ERRMSG_LEN);
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return 0;
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}
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/*
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* Reuse the XDP program in xdp_dummy.c.
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*/
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char LICENSE[] SEC("license") = "GPL";
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