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Date: Wed, 9 Oct 2019 13:44:04 -0300
From: Carlos Antonio Neira Bustos <cneirabustos@...il.com>
To: Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc: Networking <netdev@...r.kernel.org>, Yonghong Song <yhs@...com>,
ebiederm@...ssion.com, Jesper Dangaard Brouer <brouer@...hat.com>,
bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH v13 4/4] tools/testing/selftests/bpf: Add self-tests for
new helper.
On Wed, Oct 09, 2019 at 09:26:32AM -0700, Andrii Nakryiko wrote:
> On Wed, Oct 9, 2019 at 8:29 AM Carlos Neira <cneirabustos@...il.com> wrote:
> >
> > Self tests added for new helper
> >
> > Signed-off-by: Carlos Neira <cneirabustos@...il.com>
> > ---
> > tools/testing/selftests/bpf/bpf_helpers.h | 4 +
> > .../bpf/prog_tests/get_ns_current_pid_tgid.c | 85 +++++++++++++++++++
> > .../bpf/progs/get_ns_current_pid_tgid_kern.c | 53 ++++++++++++
> > 3 files changed, 142 insertions(+)
> > create mode 100644 tools/testing/selftests/bpf/prog_tests/get_ns_current_pid_tgid.c
> > create mode 100644 tools/testing/selftests/bpf/progs/get_ns_current_pid_tgid_kern.c
> >
> > diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
> > index 54a50699bbfd..16261b23e011 100644
> > --- a/tools/testing/selftests/bpf/bpf_helpers.h
> > +++ b/tools/testing/selftests/bpf/bpf_helpers.h
> > @@ -233,6 +233,10 @@ static int (*bpf_send_signal)(unsigned sig) = (void *)BPF_FUNC_send_signal;
> > static long long (*bpf_tcp_gen_syncookie)(struct bpf_sock *sk, void *ip,
> > int ip_len, void *tcp, int tcp_len) =
> > (void *) BPF_FUNC_tcp_gen_syncookie;
> > +static unsigned long long (*bpf_get_ns_current_pid_tgid)(struct bpf_pidns_info *nsinfo,
> > + unsigned int buf_size) =
> > + (void *) BPF_FUNC_get_ns_current_pid_tgid;
> > +
>
> This is obsolete as of two days ago :) We now generate this
> automatically from the bpf.h's documentation (which is currently
> broken for your helper, I replied on respective patch). So please pull
> latest bpf-next and rebase.
>
> >
> > /* llvm builtin functions that eBPF C program may use to
> > * emit BPF_LD_ABS and BPF_LD_IND instructions
> > diff --git a/tools/testing/selftests/bpf/prog_tests/get_ns_current_pid_tgid.c b/tools/testing/selftests/bpf/prog_tests/get_ns_current_pid_tgid.c
> > new file mode 100644
> > index 000000000000..a7bff0ef6677
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/prog_tests/get_ns_current_pid_tgid.c
> > @@ -0,0 +1,85 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2019 Carlos Neira cneirabustos@...il.com */
> > +#include <test_progs.h>
> > +#include <sys/stat.h>
> > +#include <sys/types.h>
> > +#include <sys/stat.h>
> > +#include <unistd.h>
> > +#include <sys/syscall.h>
> > +
> > +void test_get_ns_current_pid_tgid(void)
> > +{
> > + const char *probe_name = "syscalls/sys_enter_nanosleep";
> > + const char *file = "get_ns_current_pid_tgid_kern.o";
> > + int ns_data_map_fd, duration = 0;
> > + struct perf_event_attr attr = {};
> > + int err, efd, prog_fd, pmu_fd;
> > + __u64 ino, dev, id, nspid;
> > + struct bpf_object *obj;
> > + struct stat st;
> > + __u32 key = 0;
> > + char buf[256];
> > +
> > + err = bpf_prog_load(file, BPF_PROG_TYPE_TRACEPOINT, &obj, &prog_fd);
> > + if (CHECK(err, "prog_load", "err %d errno %d\n", err, errno))
> > + return;
> > +
> > + ns_data_map_fd = bpf_find_map(__func__, obj, "ns_data_map");
> > + if (CHECK_FAIL(ns_data_map_fd < 0))
> > + goto close_prog;
> > +
> > + pid_t tid = syscall(SYS_gettid);
> > + pid_t pid = getpid();
> > +
> > + id = (__u64) tid << 32 | pid;
> > + bpf_map_update_elem(ns_data_map_fd, &key, &id, 0);
> > +
> > + if (stat("/proc/self/ns/pid", &st))
>
> CHECK() or CHECK_FAIL() ?
>
> > + goto close_prog;
> > +
> > + dev = st.st_dev;
> > + ino = st.st_ino;
> > + key = 1;
> > + bpf_map_update_elem(ns_data_map_fd, &key, &dev, 0);
> > + key = 2;
> > + bpf_map_update_elem(ns_data_map_fd, &key, &ino, 0);
> > +
> > + snprintf(buf, sizeof(buf),
> > + "/sys/kernel/debug/tracing/events/%s/id", probe_name);
> > + efd = open(buf, O_RDONLY, 0);
> > + read(efd, buf, sizeof(buf));
> > + close(efd);
> > + attr.config = strtol(buf, NULL, 0);
> > + attr.type = PERF_TYPE_TRACEPOINT;
> > + attr.sample_type = PERF_SAMPLE_RAW;
> > + attr.sample_period = 1;
> > + attr.wakeup_events = 1;
> > +
> > + pmu_fd = syscall(__NR_perf_event_open, &attr, getpid(), -1, -1, 0);
> > + if (CHECK_FAIL(pmu_fd < 0))
> > + goto cleanup;
> > +
> > + err = ioctl(pmu_fd, PERF_EVENT_IOC_ENABLE, 0);
> > + if (CHECK_FAIL(err))
> > + goto cleanup;
> > +
> > + err = ioctl(pmu_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
> > + if (CHECK_FAIL(err))
> > + goto cleanup;
>
>
> All this attaching boilerplate is now obsolete as well, stick to
> bpf_program__attach_tracepoint(). But even better, use RAW_TRACEPOINT.
>
> > +
> > + /* trigger some syscalls */
> > + sleep(1);
> > + key = 3;
> > + err = bpf_map_lookup_elem(ns_data_map_fd, &key, &nspid);
> > + if (CHECK_FAIL(err))
> > + goto cleanup;
> > +
> > + if (CHECK(id != nspid, "Compare user pid/tgid vs. bpf pid/tgid",
> > + "Userspace pid/tgid %llu EBPF pid/tgid %llu\n", id, nspid))
> > + goto cleanup;
> > +
> > +cleanup:
> > + close(pmu_fd);
> > +close_prog:
> > + bpf_object__close(obj);
> > +}
> > diff --git a/tools/testing/selftests/bpf/progs/get_ns_current_pid_tgid_kern.c b/tools/testing/selftests/bpf/progs/get_ns_current_pid_tgid_kern.c
> > new file mode 100644
> > index 000000000000..3659aaa7c71f
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/get_ns_current_pid_tgid_kern.c
> > @@ -0,0 +1,53 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2019 Carlos Neira cneirabustos@...il.com */
> > +
> > +#include <linux/bpf.h>
> > +#include "bpf_helpers.h"
> > +
> > +struct {
> > + __uint(type, BPF_MAP_TYPE_ARRAY);
> > + __uint(max_entries, 4);
> > + __type(key, __u32);
> > + __type(value, __u64);
> > +} ns_data_map SEC(".maps");
> > +
> > +
> > +SEC("tracepoint/syscalls/sys_enter_nanosleep")
> > +int trace(void *ctx)
> > +{
> > + __u64 *val, *inum, *dev, nspidtgid, *expected_pid;
> > + struct bpf_pidns_info nsdata;
> > + __u32 key = 1;
> > +
> > + dev = bpf_map_lookup_elem(&ns_data_map, &key);
> > + if (!dev)
> > + return 0;
> > + key = 2;
> > + inum = bpf_map_lookup_elem(&ns_data_map, &key);
> > + if (!inum)
> > + return 0;
> > +
> > + nsdata.dev = *dev;
> > + nsdata.inum = *inum;
> > +
> > + if (bpf_get_ns_current_pid_tgid(&nsdata, sizeof(struct bpf_pidns_info)))
> > + return 0;
> > +
> > + nspidtgid = (__u64)nsdata.tgid << 32 | nsdata.pid;
> > + key = 0;
> > + expected_pid = bpf_map_lookup_elem(&ns_data_map, &key);
> > +
> > + if (!expected_pid || *expected_pid != nspidtgid)
> > + return 0;
> > +
> > + key = 3;
> > + val = bpf_map_lookup_elem(&ns_data_map, &key);
>
> Please, use global data for this, will make this BPF program much
> shorter, cleaner, and up to the point. See recent patch by Daniel T.
> Lee, or some of the tests I added (e.g.,
> progs/test_core_reloc_kernel.c)
>
> > +
> > + if (val)
> > + *val = nspidtgid;
> > +
> > + return 0;
> > +}
> > +
> > +char _license[] SEC("license") = "GPL";
> > +__u32 _version SEC("version") = 1;
>
> You can drop version now (recent stuff), it's not required by libbpf anymore.
>
> > --
> > 2.20.1
> >
Thanks for checking this out!, I'll rebase to current bpf-next and
checkout progs/test_core_reloc_kernel.c.
Bests
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