Subject: Re: [PATCH bpf-next v2 3/3] selftests/bpf: add simple BPF_PROG_TEST_RUN examples for flow dissector

From: Stanislav Fomichev <[email-masked]>
Date: Fri, 25 Jan 2019 16:58:42 -0800

On 01/25, Song Liu wrote:
> On Thu, Jan 24, 2019 at 8:52 AM Stanislav Fomichev <[email-masked]> wrote:
> >
> > Use existing pkt_v4 and pkt_v6 to make sure flow_keys are what we want.
> >
> > Also, add new bpf_flow_load routine (and flow_dissector_load.h header)
> > that loads bpf_flow.o program and does all required setup.
> >
> > Signed-off-by: Stanislav Fomichev <[email-masked]>
> > ---
> >  tools/testing/selftests/bpf/Makefile          |  3 +
> >  .../selftests/bpf/flow_dissector_load.c       | 43 ++--------
> >  .../selftests/bpf/flow_dissector_load.h       | 55 +++++++++++++
> >  tools/testing/selftests/bpf/test_progs.c      | 78 ++++++++++++++++++-
> >  4 files changed, 139 insertions(+), 40 deletions(-)
> >  create mode 100644 tools/testing/selftests/bpf/flow_dissector_load.h
> >
> > diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> > index 70229de510f5..ade67470a152 100644
> > --- a/tools/testing/selftests/bpf/Makefile
> > +++ b/tools/testing/selftests/bpf/Makefile
> > @@ -19,6 +19,9 @@ all: $(TEST_CUSTOM_PROGS)
> >  $(TEST_CUSTOM_PROGS): $(OUTPUT)/%: %.c
> >         $(CC) -o $(TEST_CUSTOM_PROGS) -static $< -Wl,--build-id
> >
> > +flow_dissector_load.c: flow_dissector_load.h
> > +test_run.c: flow_dissector_load.h
> > +
> >  # Order correspond to 'make run_tests' order
> >  TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \
> >         test_align test_verifier_log test_dev_cgroup test_tcpbpf_user \
> > diff --git a/tools/testing/selftests/bpf/flow_dissector_load.c b/tools/testing/selftests/bpf/flow_dissector_load.c
> > index ae8180b11d5f..77cafa66d048 100644
> > --- a/tools/testing/selftests/bpf/flow_dissector_load.c
> > +++ b/tools/testing/selftests/bpf/flow_dissector_load.c
> > @@ -12,6 +12,7 @@
> >  #include <bpf/libbpf.h>
> >
> >  #include "bpf_rlimit.h"
> > +#include "flow_dissector_load.h"
> >
> >  const char *cfg_pin_path = "/sys/fs/bpf/flow_dissector";
> >  const char *cfg_map_name = "jmp_table";
> > @@ -21,46 +22,13 @@ char *cfg_path_name;
> >
> >  static void load_and_attach_program(void)
> >  {
> > -       struct bpf_program *prog, *main_prog;
> > -       struct bpf_map *prog_array;
> > -       int i, fd, prog_fd, ret;
> > +       int prog_fd, ret;
> >         struct bpf_object *obj;
> > -       int prog_array_fd;
> >
> > -       ret = bpf_prog_load(cfg_path_name, BPF_PROG_TYPE_FLOW_DISSECTOR, &obj,
> > -                           &prog_fd);
> > +       ret = bpf_flow_load(&obj, cfg_path_name, cfg_section_name,
> > +                           cfg_map_name, &prog_fd);
> >         if (ret)
> > -               error(1, 0, "bpf_prog_load %s", cfg_path_name);
> > -
> > -       main_prog = bpf_object__find_program_by_title(obj, cfg_section_name);
> > -       if (!main_prog)
> > -               error(1, 0, "bpf_object__find_program_by_title %s",
> > -                     cfg_section_name);
> > -
> > -       prog_fd = bpf_program__fd(main_prog);
> > -       if (prog_fd < 0)
> > -               error(1, 0, "bpf_program__fd");
> > -
> > -       prog_array = bpf_object__find_map_by_name(obj, cfg_map_name);
> > -       if (!prog_array)
> > -               error(1, 0, "bpf_object__find_map_by_name %s", cfg_map_name);
> > -
> > -       prog_array_fd = bpf_map__fd(prog_array);
> > -       if (prog_array_fd < 0)
> > -               error(1, 0, "bpf_map__fd %s", cfg_map_name);
> > -
> > -       i = 0;
> > -       bpf_object__for_each_program(prog, obj) {
> > -               fd = bpf_program__fd(prog);
> > -               if (fd < 0)
> > -                       error(1, 0, "bpf_program__fd");
> > -
> > -               if (fd != prog_fd) {
> > -                       printf("%d: %s\n", i, bpf_program__title(prog, false));
> > -                       bpf_map_update_elem(prog_array_fd, &i, &fd, BPF_ANY);
> > -                       ++i;
> > -               }
> > -       }
> > +               error(1, 0, "bpf_flow_load %s", cfg_path_name);
> >
> >         ret = bpf_prog_attach(prog_fd, 0 /* Ignore */, BPF_FLOW_DISSECTOR, 0);
> >         if (ret)
> > @@ -69,7 +37,6 @@ static void load_and_attach_program(void)
> >         ret = bpf_object__pin(obj, cfg_pin_path);
> >         if (ret)
> >                 error(1, 0, "bpf_object__pin %s", cfg_pin_path);
> > -
> >  }
> >
> >  static void detach_program(void)
> > diff --git a/tools/testing/selftests/bpf/flow_dissector_load.h b/tools/testing/selftests/bpf/flow_dissector_load.h
> > new file mode 100644
> > index 000000000000..41dd6959feb0
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/flow_dissector_load.h
> > @@ -0,0 +1,55 @@
> > +/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
> > +#ifndef FLOW_DISSECTOR_LOAD
> > +#define FLOW_DISSECTOR_LOAD
> > +
> > +#include <bpf/bpf.h>
> > +#include <bpf/libbpf.h>
> > +
> > +static inline int bpf_flow_load(struct bpf_object **obj,
> > +                               const char *path,
> > +                               const char *section_name,
> > +                               const char *map_name,
> > +                               int *prog_fd)
> > +{
> > +       struct bpf_program *prog, *main_prog;
> > +       struct bpf_map *prog_array;
> > +       int prog_array_fd;
> > +       int ret, fd, i;
> > +
> > +       ret = bpf_prog_load(path, BPF_PROG_TYPE_FLOW_DISSECTOR, obj,
> > +                           prog_fd);
> > +       if (ret)
> > +               return ret;
> > +
> > +       main_prog = bpf_object__find_program_by_title(*obj, section_name);
> > +       if (!main_prog)
> > +               return ret;
> > +
> > +       *prog_fd = bpf_program__fd(main_prog);
> > +       if (*prog_fd < 0)
> > +               return ret;
> > +
> > +       prog_array = bpf_object__find_map_by_name(*obj, map_name);
> > +       if (!prog_array)
> > +               return ret;
> > +
> > +       prog_array_fd = bpf_map__fd(prog_array);
> > +       if (prog_array_fd < 0)
> > +               return ret;
> > +
> > +       i = 0;
> > +       bpf_object__for_each_program(prog, *obj) {
> > +               fd = bpf_program__fd(prog);
> > +               if (fd < 0)
> > +                       return fd;
> > +
> > +               if (fd != *prog_fd) {
> > +                       bpf_map_update_elem(prog_array_fd, &i, &fd, BPF_ANY);
> > +                       ++i;
> > +               }
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +#endif /* FLOW_DISSECTOR_LOAD */
> > diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
> > index 126fc624290d..5f46680d4ad4 100644
> > --- a/tools/testing/selftests/bpf/test_progs.c
> > +++ b/tools/testing/selftests/bpf/test_progs.c
> > @@ -39,6 +39,7 @@ typedef __u16 __sum16;
> >  #include "bpf_endian.h"
> >  #include "bpf_rlimit.h"
> >  #include "trace_helpers.h"
> > +#include "flow_dissector_load.h"
> >
> >  static int error_cnt, pass_cnt;
> >  static bool jit_enabled;
> > @@ -53,9 +54,10 @@ static struct {
> >  } __packed pkt_v4 = {
> >         .eth.h_proto = __bpf_constant_htons(ETH_P_IP),
> >         .iph.ihl = 5,
> > -       .iph.protocol = 6,
> > +       .iph.protocol = IPPROTO_TCP,
> >         .iph.tot_len = __bpf_constant_htons(MAGIC_BYTES),
> >         .tcp.urg_ptr = 123,
> > +       .tcp.doff = 5,
> >  };
> >
> >  /* ipv6 test vector */
> > @@ -65,9 +67,10 @@ static struct {
> >         struct tcphdr tcp;
> >  } __packed pkt_v6 = {
> >         .eth.h_proto = __bpf_constant_htons(ETH_P_IPV6),
> > -       .iph.nexthdr = 6,
> > +       .iph.nexthdr = IPPROTO_TCP,
> >         .iph.payload_len = __bpf_constant_htons(MAGIC_BYTES),
> >         .tcp.urg_ptr = 123,
> > +       .tcp.doff = 5,
> >  };
> 
> Why do we need these changes? They seem unrelated to me.
doff = 5 is required for the current flow dissector program
implementation (bpf_flow.c), without it it doesn't return success:
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git/tree/tools/testing/selftests/bpf/bpf_flow.c#n188

6 to IPPROTO_TCP just to look nice, since I'm already touching it.

> 
> Thanks,
> Song
> 
> 
> >
> >  #define _CHECK(condition, tag, duration, format...) ({                 \
> > @@ -1882,6 +1885,76 @@ static void test_queue_stack_map(int type)
> >         bpf_object__close(obj);
> >  }
> >
> > +#define CHECK_FLOW_KEYS(desc, got, expected)                           \
> > +       CHECK(memcmp(&got, &expected, sizeof(got)) != 0,                \
> > +             desc,                                                     \
> > +             "nhoff=%u/%u "                                            \
> > +             "thoff=%u/%u "                                            \
> > +             "addr_proto=0x%x/0x%x "                                   \
> > +             "is_frag=%u/%u "                                          \
> > +             "is_first_frag=%u/%u "                                    \
> > +             "is_encap=%u/%u "                                         \
> > +             "n_proto=0x%x/0x%x "                                      \
> > +             "sport=%u/%u "                                            \
> > +             "dport=%u/%u\n",                                          \
> > +             got.nhoff, expected.nhoff,                                \
> > +             got.thoff, expected.thoff,                                \
> > +             got.addr_proto, expected.addr_proto,                      \
> > +             got.is_frag, expected.is_frag,                            \
> > +             got.is_first_frag, expected.is_first_frag,                \
> > +             got.is_encap, expected.is_encap,                          \
> > +             got.n_proto, expected.n_proto,                            \
> > +             got.sport, expected.sport,                                \
> > +             got.dport, expected.dport)
> > +
> > +static struct bpf_flow_keys pkt_v4_flow_keys = {
> > +       .nhoff = 0,
> > +       .thoff = sizeof(struct iphdr),
> > +       .addr_proto = ETH_P_IP,
> > +       .ip_proto = IPPROTO_TCP,
> > +       .n_proto = bpf_htons(ETH_P_IP),
> > +};
> > +
> > +static struct bpf_flow_keys pkt_v6_flow_keys = {
> > +       .nhoff = 0,
> > +       .thoff = sizeof(struct ipv6hdr),
> > +       .addr_proto = ETH_P_IPV6,
> > +       .ip_proto = IPPROTO_TCP,
> > +       .n_proto = bpf_htons(ETH_P_IPV6),
> > +};
> > +
> > +static void test_flow_dissector(void)
> > +{
> > +       struct bpf_flow_keys flow_keys;
> > +       struct bpf_object *obj;
> > +       __u32 duration, retval;
> > +       int err, prog_fd;
> > +       __u32 size;
> > +
> > +       err = bpf_flow_load(&obj, "./bpf_flow.o", "flow_dissector",
> > +                           "jmp_table", &prog_fd);
> > +       if (err) {
> > +               error_cnt++;
> > +               return;
> > +       }
> > +
> > +       err = bpf_prog_test_run(prog_fd, 10, &pkt_v4, sizeof(pkt_v4),
> > +                               &flow_keys, &size, &retval, &duration);
> > +       CHECK(size != sizeof(flow_keys) || err || retval != 1, "ipv4",
> > +             "err %d errno %d retval %d duration %d size %u/%lu\n",
> > +             err, errno, retval, duration, size, sizeof(flow_keys));
> > +       CHECK_FLOW_KEYS("ipv4_flow_keys", flow_keys, pkt_v4_flow_keys);
> > +
> > +       err = bpf_prog_test_run(prog_fd, 10, &pkt_v6, sizeof(pkt_v6),
> > +                               &flow_keys, &size, &retval, &duration);
> > +       CHECK(size != sizeof(flow_keys) || err || retval != 1, "ipv6",
> > +             "err %d errno %d retval %d duration %d size %u/%lu\n",
> > +             err, errno, retval, duration, size, sizeof(flow_keys));
> > +       CHECK_FLOW_KEYS("ipv6_flow_keys", flow_keys, pkt_v6_flow_keys);
> > +
> > +       bpf_object__close(obj);
> > +}
> > +
> >  int main(void)
> >  {
> >         srand(time(NULL));
> > @@ -1909,6 +1982,7 @@ int main(void)
> >         test_reference_tracking();
> >         test_queue_stack_map(QUEUE);
> >         test_queue_stack_map(STACK);
> > +       test_flow_dissector();
> >
> >         printf("Summary: %d PASSED, %d FAILED\n", pass_cnt, error_cnt);
> >         return error_cnt ? EXIT_FAILURE : EXIT_SUCCESS;
> > --
> > 2.20.1.321.g9e740568ce-goog
> >