| Message ID | 20220730000809.312891-2-sdf@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf-next,1/2] bpf: use proper target btf when exporting attach_btf_obj_id | expand |
On Fri, Jul 29, 2022 at 5:08 PM Stanislav Fomichev <sdf@google.com> wrote: > > Apparently, no existing selftest covers it. Add a new one where > we load cgroup/bind4 program and attach fentry to it. > Calling bpf_obj_get_info_by_fd on the fentry program > should return non-zero btf_id/btf_obj_id instead of crashing the kernel. > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > --- Looks good to me overall, with a few nits. > .../selftests/bpf/prog_tests/attach_to_bpf.c | 109 ++++++++++++++++++ > .../selftests/bpf/progs/attach_to_bpf.c | 12 ++ > 2 files changed, 121 insertions(+) > create mode 100644 tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > create mode 100644 tools/testing/selftests/bpf/progs/attach_to_bpf.c > > diff --git a/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > new file mode 100644 > index 000000000000..fcf726c5ff0f > --- /dev/null > +++ b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > @@ -0,0 +1,109 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#define _GNU_SOURCE > +#include <stdlib.h> > +#include <bpf/btf.h> > +#include <test_progs.h> > +#include <network_helpers.h> > +#include "attach_to_bpf.skel.h" > + > +char bpf_log_buf[BPF_LOG_BUF_SIZE]; > + > +static int find_prog_btf_id(const char *name, __u32 attach_prog_fd) > +{ > + struct bpf_prog_info info = {}; > + __u32 info_len = sizeof(info); > + struct btf *btf; > + int err; > + > + err = bpf_obj_get_info_by_fd(attach_prog_fd, &info, &info_len); > + if (err) > + return err; > + > + if (!info.btf_id) > + return -EINVAL; > + > + btf = btf__load_from_kernel_by_id(info.btf_id); > + err = libbpf_get_error(btf); > + if (err) > + return err; > + > + err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); nit: Prefer use a separate variable like 'btf_id' instead of using 'err'. > + btf__free(btf); > + if (err <= 0) > + return err; > + > + return err; > +} > + > +int load_fentry(int attach_prog_fd, int attach_btf_id) > +{ > + LIBBPF_OPTS(bpf_prog_load_opts, opts, > + .expected_attach_type = BPF_TRACE_FENTRY, > + .attach_prog_fd = attach_prog_fd, > + .attach_btf_id = attach_btf_id, > + .log_buf = bpf_log_buf, > + .log_size = sizeof(bpf_log_buf), > + ); > + struct bpf_insn insns[] = { > + BPF_MOV64_IMM(BPF_REG_0, 0), > + BPF_EXIT_INSN(), > + }; > + int ret; > + > + ret = bpf_prog_load(BPF_PROG_TYPE_TRACING, > + "bind4_fentry", > + "GPL", > + insns, > + ARRAY_SIZE(insns), > + &opts); > + if (ret) > + printf("verifier log: %s\n", bpf_log_buf); Do we need to print log? If print logging isn't necessary, we could directly return bpf_prog_load(). Seems simpler. > + return ret; > +} > + > +void test_attach_to_bpf(void) > +{ > + struct attach_to_bpf *skel = NULL; > + struct bpf_prog_info info = {}; > + __u32 info_len = sizeof(info); > + int cgroup_fd = -1; > + int fentry_fd = -1; > + int btf_id; > + > + cgroup_fd = test__join_cgroup("/attach_to_bpf"); > + if (!ASSERT_GE(cgroup_fd, 0, "cgroup_fd")) > + return; > + > + skel = attach_to_bpf__open_and_load(); > + if (!ASSERT_OK_PTR(skel, "skel")) > + goto cleanup; > + > + skel->links.bind4 = bpf_program__attach_cgroup(skel->progs.bind4, cgroup_fd); > + if (!ASSERT_OK_PTR(skel, "bpf_program__attach_cgroup")) > + goto cleanup; > + > + btf_id = find_prog_btf_id("bind4", bpf_program__fd(skel->progs.bind4)); > + if (!ASSERT_GE(btf_id, 0, "find_prog_btf_id")) > + goto cleanup; > + > + fentry_fd = load_fentry(bpf_program__fd(skel->progs.bind4), btf_id); > + if (!ASSERT_GE(fentry_fd, 0, "load_fentry")) > + goto cleanup; > + > + /* Make sure bpf_obj_get_info_by_fd works correctly when attaching > + * to another BPF program. > + */ > + > + if (!ASSERT_OK(bpf_obj_get_info_by_fd(fentry_fd, &info, &info_len), > + "bpf_obj_get_info_by_fd")) > + goto cleanup; > + Conditional checking may not be necessary. Just ASSERT_OK(bpf_obj_get_info_by_fd(...)). Looks more compact. > + ASSERT_EQ(info.btf_id, 0, "info.btf_id"); > + ASSERT_GT(info.attach_btf_id, 0, "info.attach_btf_id"); > + ASSERT_GT(info.attach_btf_obj_id, 0, "info.attach_btf_obj_id"); > + > +cleanup: > + close(cgroup_fd); > + close(fentry_fd); > + attach_to_bpf__destroy(skel); > +} > diff --git a/tools/testing/selftests/bpf/progs/attach_to_bpf.c b/tools/testing/selftests/bpf/progs/attach_to_bpf.c > new file mode 100644 > index 000000000000..3f111fe96f8f > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/attach_to_bpf.c > @@ -0,0 +1,12 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include <linux/bpf.h> > +#include <bpf/bpf_helpers.h> > + > +SEC("cgroup/bind4") > +int bind4(struct bpf_sock_addr *ctx) > +{ > + return 1; > +} > + > +char _license[] SEC("license") = "GPL"; > -- > 2.37.1.455.g008518b4e5-goog >
On Fri, Jul 29, 2022 at 5:56 PM Hao Luo <haoluo@google.com> wrote: > > On Fri, Jul 29, 2022 at 5:08 PM Stanislav Fomichev <sdf@google.com> wrote: > > > > Apparently, no existing selftest covers it. Add a new one where > > we load cgroup/bind4 program and attach fentry to it. > > Calling bpf_obj_get_info_by_fd on the fentry program > > should return non-zero btf_id/btf_obj_id instead of crashing the kernel. > > > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > > --- > > Looks good to me overall, with a few nits. Thank you for the review! Will respin on Mon. > > .../selftests/bpf/prog_tests/attach_to_bpf.c | 109 ++++++++++++++++++ > > .../selftests/bpf/progs/attach_to_bpf.c | 12 ++ > > 2 files changed, 121 insertions(+) > > create mode 100644 tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > > create mode 100644 tools/testing/selftests/bpf/progs/attach_to_bpf.c > > > > diff --git a/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > > new file mode 100644 > > index 000000000000..fcf726c5ff0f > > --- /dev/null > > +++ b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > > @@ -0,0 +1,109 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +#define _GNU_SOURCE > > +#include <stdlib.h> > > +#include <bpf/btf.h> > > +#include <test_progs.h> > > +#include <network_helpers.h> > > +#include "attach_to_bpf.skel.h" > > + > > +char bpf_log_buf[BPF_LOG_BUF_SIZE]; > > + > > +static int find_prog_btf_id(const char *name, __u32 attach_prog_fd) > > +{ > > + struct bpf_prog_info info = {}; > > + __u32 info_len = sizeof(info); > > + struct btf *btf; > > + int err; > > + > > + err = bpf_obj_get_info_by_fd(attach_prog_fd, &info, &info_len); > > + if (err) > > + return err; > > + > > + if (!info.btf_id) > > + return -EINVAL; > > + > > + btf = btf__load_from_kernel_by_id(info.btf_id); > > + err = libbpf_get_error(btf); > > + if (err) > > + return err; > > + > > + err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); > > nit: Prefer use a separate variable like 'btf_id' instead of using 'err'. SG! > > + btf__free(btf); > > + if (err <= 0) > > + return err; > > + > > + return err; > > +} > > + > > +int load_fentry(int attach_prog_fd, int attach_btf_id) > > +{ > > + LIBBPF_OPTS(bpf_prog_load_opts, opts, > > + .expected_attach_type = BPF_TRACE_FENTRY, > > + .attach_prog_fd = attach_prog_fd, > > + .attach_btf_id = attach_btf_id, > > + .log_buf = bpf_log_buf, > > + .log_size = sizeof(bpf_log_buf), > > + ); > > + struct bpf_insn insns[] = { > > + BPF_MOV64_IMM(BPF_REG_0, 0), > > + BPF_EXIT_INSN(), > > + }; > > + int ret; > > + > > + ret = bpf_prog_load(BPF_PROG_TYPE_TRACING, > > + "bind4_fentry", > > + "GPL", > > + insns, > > + ARRAY_SIZE(insns), > > + &opts); > > + if (ret) > > + printf("verifier log: %s\n", bpf_log_buf); > > Do we need to print log? If print logging isn't necessary, we could > directly return bpf_prog_load(). Seems simpler. We don't really need it. I've been using it during development, but I guess it should be fine to drop since the test is passing now :-) > > + return ret; > > +} > > + > > +void test_attach_to_bpf(void) > > +{ > > + struct attach_to_bpf *skel = NULL; > > + struct bpf_prog_info info = {}; > > + __u32 info_len = sizeof(info); > > + int cgroup_fd = -1; > > + int fentry_fd = -1; > > + int btf_id; > > + > > + cgroup_fd = test__join_cgroup("/attach_to_bpf"); > > + if (!ASSERT_GE(cgroup_fd, 0, "cgroup_fd")) > > + return; > > + > > + skel = attach_to_bpf__open_and_load(); > > + if (!ASSERT_OK_PTR(skel, "skel")) > > + goto cleanup; > > + > > + skel->links.bind4 = bpf_program__attach_cgroup(skel->progs.bind4, cgroup_fd); > > + if (!ASSERT_OK_PTR(skel, "bpf_program__attach_cgroup")) > > + goto cleanup; > > + > > + btf_id = find_prog_btf_id("bind4", bpf_program__fd(skel->progs.bind4)); > > + if (!ASSERT_GE(btf_id, 0, "find_prog_btf_id")) > > + goto cleanup; > > + > > + fentry_fd = load_fentry(bpf_program__fd(skel->progs.bind4), btf_id); > > + if (!ASSERT_GE(fentry_fd, 0, "load_fentry")) > > + goto cleanup; > > + > > + /* Make sure bpf_obj_get_info_by_fd works correctly when attaching > > + * to another BPF program. > > + */ > > + > > + if (!ASSERT_OK(bpf_obj_get_info_by_fd(fentry_fd, &info, &info_len), > > + "bpf_obj_get_info_by_fd")) > > + goto cleanup; > > + > > Conditional checking may not be necessary. Just > ASSERT_OK(bpf_obj_get_info_by_fd(...)). Looks more compact. Ack, makes sense. > > + ASSERT_EQ(info.btf_id, 0, "info.btf_id"); > > + ASSERT_GT(info.attach_btf_id, 0, "info.attach_btf_id"); > > + ASSERT_GT(info.attach_btf_obj_id, 0, "info.attach_btf_obj_id"); > > + > > +cleanup: > > + close(cgroup_fd); > > + close(fentry_fd); > > + attach_to_bpf__destroy(skel); > > +} > > diff --git a/tools/testing/selftests/bpf/progs/attach_to_bpf.c b/tools/testing/selftests/bpf/progs/attach_to_bpf.c > > new file mode 100644 > > index 000000000000..3f111fe96f8f > > --- /dev/null > > +++ b/tools/testing/selftests/bpf/progs/attach_to_bpf.c > > @@ -0,0 +1,12 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > + > > +#include <linux/bpf.h> > > +#include <bpf/bpf_helpers.h> > > + > > +SEC("cgroup/bind4") > > +int bind4(struct bpf_sock_addr *ctx) > > +{ > > + return 1; > > +} > > + > > +char _license[] SEC("license") = "GPL"; > > -- > > 2.37.1.455.g008518b4e5-goog > >
On Fri, Jul 29, 2022 at 05:08:09PM -0700, Stanislav Fomichev wrote: > Apparently, no existing selftest covers it. Add a new one where > we load cgroup/bind4 program and attach fentry to it. > Calling bpf_obj_get_info_by_fd on the fentry program > should return non-zero btf_id/btf_obj_id instead of crashing the kernel. > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > --- > .../selftests/bpf/prog_tests/attach_to_bpf.c | 109 ++++++++++++++++++ > .../selftests/bpf/progs/attach_to_bpf.c | 12 ++ > 2 files changed, 121 insertions(+) > create mode 100644 tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > create mode 100644 tools/testing/selftests/bpf/progs/attach_to_bpf.c > > diff --git a/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > new file mode 100644 > index 000000000000..fcf726c5ff0f > --- /dev/null > +++ b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > @@ -0,0 +1,109 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#define _GNU_SOURCE > +#include <stdlib.h> > +#include <bpf/btf.h> > +#include <test_progs.h> > +#include <network_helpers.h> > +#include "attach_to_bpf.skel.h" > + > +char bpf_log_buf[BPF_LOG_BUF_SIZE]; static > + > +static int find_prog_btf_id(const char *name, __u32 attach_prog_fd) > +{ > + struct bpf_prog_info info = {}; > + __u32 info_len = sizeof(info); > + struct btf *btf; > + int err; > + > + err = bpf_obj_get_info_by_fd(attach_prog_fd, &info, &info_len); > + if (err) > + return err; > + > + if (!info.btf_id) > + return -EINVAL; > + > + btf = btf__load_from_kernel_by_id(info.btf_id); > + err = libbpf_get_error(btf); > + if (err) > + return err; > + > + err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); > + btf__free(btf); > + if (err <= 0) > + return err; > + > + return err; > +} > + > +int load_fentry(int attach_prog_fd, int attach_btf_id) static > +{ > + LIBBPF_OPTS(bpf_prog_load_opts, opts, > + .expected_attach_type = BPF_TRACE_FENTRY, > + .attach_prog_fd = attach_prog_fd, > + .attach_btf_id = attach_btf_id, > + .log_buf = bpf_log_buf, > + .log_size = sizeof(bpf_log_buf), > + ); > + struct bpf_insn insns[] = { > + BPF_MOV64_IMM(BPF_REG_0, 0), > + BPF_EXIT_INSN(), > + }; > + int ret; > + > + ret = bpf_prog_load(BPF_PROG_TYPE_TRACING, > + "bind4_fentry", > + "GPL", > + insns, > + ARRAY_SIZE(insns), > + &opts); > + if (ret) > + printf("verifier log: %s\n", bpf_log_buf); If this fentry prog is in the attach_to_bpf.c and load by skel, this printf and the bpf_log_buf can go away. I wonder if it can use the '?' like SEC("?cgroup/bind4") and SEC("?fentry"). Then opens attach_to_bpf.skel.h twice and use bpf_program__set_autoload() to load individual program. Another option could be to reuse the progs/bind4_prog.c and directly put the fentry program in the attach_to_bpf.c. btw, this test feels like something that could be a few line addition to the test_fexit_bpf2bpf_common() in fexit_bpf2bpf.c. Adding one to test fentry into a cgroup bpf prog is also good. No strong opinion here also. > + return ret; > +} > + > +void test_attach_to_bpf(void) > +{ > + struct attach_to_bpf *skel = NULL; > + struct bpf_prog_info info = {}; > + __u32 info_len = sizeof(info); > + int cgroup_fd = -1; > + int fentry_fd = -1; > + int btf_id; > + > + cgroup_fd = test__join_cgroup("/attach_to_bpf"); > + if (!ASSERT_GE(cgroup_fd, 0, "cgroup_fd")) > + return; > + > + skel = attach_to_bpf__open_and_load(); > + if (!ASSERT_OK_PTR(skel, "skel")) > + goto cleanup; > + > + skel->links.bind4 = bpf_program__attach_cgroup(skel->progs.bind4, cgroup_fd); > + if (!ASSERT_OK_PTR(skel, "bpf_program__attach_cgroup")) > + goto cleanup; > + > + btf_id = find_prog_btf_id("bind4", bpf_program__fd(skel->progs.bind4)); > + if (!ASSERT_GE(btf_id, 0, "find_prog_btf_id")) > + goto cleanup; > + > + fentry_fd = load_fentry(bpf_program__fd(skel->progs.bind4), btf_id); > + if (!ASSERT_GE(fentry_fd, 0, "load_fentry")) > + goto cleanup; > + > + /* Make sure bpf_obj_get_info_by_fd works correctly when attaching > + * to another BPF program. > + */ > + > + if (!ASSERT_OK(bpf_obj_get_info_by_fd(fentry_fd, &info, &info_len), > + "bpf_obj_get_info_by_fd")) > + goto cleanup; > + > + ASSERT_EQ(info.btf_id, 0, "info.btf_id"); > + ASSERT_GT(info.attach_btf_id, 0, "info.attach_btf_id"); > + ASSERT_GT(info.attach_btf_obj_id, 0, "info.attach_btf_obj_id"); > + > +cleanup: > + close(cgroup_fd); > + close(fentry_fd); > + attach_to_bpf__destroy(skel); > +} > diff --git a/tools/testing/selftests/bpf/progs/attach_to_bpf.c b/tools/testing/selftests/bpf/progs/attach_to_bpf.c > new file mode 100644 > index 000000000000..3f111fe96f8f > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/attach_to_bpf.c nit. attach_to_bpf.c sounds too broad. May be fentry_to_cgroup_bpf.c ? > @@ -0,0 +1,12 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include <linux/bpf.h> > +#include <bpf/bpf_helpers.h> > + > +SEC("cgroup/bind4") > +int bind4(struct bpf_sock_addr *ctx) > +{ > + return 1; > +} > + > +char _license[] SEC("license") = "GPL"; > -- > 2.37.1.455.g008518b4e5-goog >
On Mon, Aug 1, 2022 at 10:45 AM Martin KaFai Lau <kafai@fb.com> wrote: > > On Fri, Jul 29, 2022 at 05:08:09PM -0700, Stanislav Fomichev wrote: > > Apparently, no existing selftest covers it. Add a new one where > > we load cgroup/bind4 program and attach fentry to it. > > Calling bpf_obj_get_info_by_fd on the fentry program > > should return non-zero btf_id/btf_obj_id instead of crashing the kernel. > > > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > > --- > > .../selftests/bpf/prog_tests/attach_to_bpf.c | 109 ++++++++++++++++++ > > .../selftests/bpf/progs/attach_to_bpf.c | 12 ++ > > 2 files changed, 121 insertions(+) > > create mode 100644 tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > > create mode 100644 tools/testing/selftests/bpf/progs/attach_to_bpf.c > > > > diff --git a/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > > new file mode 100644 > > index 000000000000..fcf726c5ff0f > > --- /dev/null > > +++ b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > > @@ -0,0 +1,109 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +#define _GNU_SOURCE > > +#include <stdlib.h> > > +#include <bpf/btf.h> > > +#include <test_progs.h> > > +#include <network_helpers.h> > > +#include "attach_to_bpf.skel.h" > > + > > +char bpf_log_buf[BPF_LOG_BUF_SIZE]; > static Will remove bpf_log_buf. Sent v2 too soon :-( > > + > > +static int find_prog_btf_id(const char *name, __u32 attach_prog_fd) > > +{ > > + struct bpf_prog_info info = {}; > > + __u32 info_len = sizeof(info); > > + struct btf *btf; > > + int err; > > + > > + err = bpf_obj_get_info_by_fd(attach_prog_fd, &info, &info_len); > > + if (err) > > + return err; > > + > > + if (!info.btf_id) > > + return -EINVAL; > > + > > + btf = btf__load_from_kernel_by_id(info.btf_id); > > + err = libbpf_get_error(btf); > > + if (err) > > + return err; > > + > > + err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); > > + btf__free(btf); > > + if (err <= 0) > > + return err; > > + > > + return err; > > +} > > + > > +int load_fentry(int attach_prog_fd, int attach_btf_id) > static Thx! > > +{ > > + LIBBPF_OPTS(bpf_prog_load_opts, opts, > > + .expected_attach_type = BPF_TRACE_FENTRY, > > + .attach_prog_fd = attach_prog_fd, > > + .attach_btf_id = attach_btf_id, > > + .log_buf = bpf_log_buf, > > + .log_size = sizeof(bpf_log_buf), > > + ); > > + struct bpf_insn insns[] = { > > + BPF_MOV64_IMM(BPF_REG_0, 0), > > + BPF_EXIT_INSN(), > > + }; > > + int ret; > > + > > + ret = bpf_prog_load(BPF_PROG_TYPE_TRACING, > > + "bind4_fentry", > > + "GPL", > > + insns, > > + ARRAY_SIZE(insns), > > + &opts); > > + if (ret) > > + printf("verifier log: %s\n", bpf_log_buf); > If this fentry prog is in the attach_to_bpf.c and load by skel, this printf > and the bpf_log_buf can go away. I wonder if it can use the '?' like > SEC("?cgroup/bind4") and SEC("?fentry"). Then opens attach_to_bpf.skel.h > twice and use bpf_program__set_autoload() to load individual program . Good ideal, let me try to see if doing "?fentry" is easier.. (unless we agree to keep load_fentry, see below) > Another option could be to reuse the progs/bind4_prog.c and directly > put the fentry program in the attach_to_bpf.c. > > btw, this test feels like something that could be a few line > addition to the test_fexit_bpf2bpf_common() in fexit_bpf2bpf.c. > Adding one to test fentry into a cgroup bpf prog is also good. > No strong opinion here also. I was trying to reuse fexit_bpf2bpf initially but I sank too much time into it and decided that it might be easier to write a simpler/separate reproducer instead :-( How about we reuse progs/bind4_prog.c and keep load_fentry() ? And put this new test in fexit_bpf2bpf.c ?
On Mon, Aug 01, 2022 at 11:23:56AM -0700, Stanislav Fomichev wrote: > On Mon, Aug 1, 2022 at 10:45 AM Martin KaFai Lau <kafai@fb.com> wrote: > > > > On Fri, Jul 29, 2022 at 05:08:09PM -0700, Stanislav Fomichev wrote: > > > Apparently, no existing selftest covers it. Add a new one where > > > we load cgroup/bind4 program and attach fentry to it. > > > Calling bpf_obj_get_info_by_fd on the fentry program > > > should return non-zero btf_id/btf_obj_id instead of crashing the kernel. > > > > > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > > > --- > > > .../selftests/bpf/prog_tests/attach_to_bpf.c | 109 ++++++++++++++++++ > > > .../selftests/bpf/progs/attach_to_bpf.c | 12 ++ > > > 2 files changed, 121 insertions(+) > > > create mode 100644 tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > > > create mode 100644 tools/testing/selftests/bpf/progs/attach_to_bpf.c > > > > > > diff --git a/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > > > new file mode 100644 > > > index 000000000000..fcf726c5ff0f > > > --- /dev/null > > > +++ b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > > > @@ -0,0 +1,109 @@ > > > +// SPDX-License-Identifier: GPL-2.0 > > > +#define _GNU_SOURCE > > > +#include <stdlib.h> > > > +#include <bpf/btf.h> > > > +#include <test_progs.h> > > > +#include <network_helpers.h> > > > +#include "attach_to_bpf.skel.h" > > > + > > > +char bpf_log_buf[BPF_LOG_BUF_SIZE]; > > static > > Will remove bpf_log_buf. Sent v2 too soon :-( > > > > + > > > +static int find_prog_btf_id(const char *name, __u32 attach_prog_fd) > > > +{ > > > + struct bpf_prog_info info = {}; > > > + __u32 info_len = sizeof(info); > > > + struct btf *btf; > > > + int err; > > > + > > > + err = bpf_obj_get_info_by_fd(attach_prog_fd, &info, &info_len); > > > + if (err) > > > + return err; > > > + > > > + if (!info.btf_id) > > > + return -EINVAL; > > > + > > > + btf = btf__load_from_kernel_by_id(info.btf_id); > > > + err = libbpf_get_error(btf); > > > + if (err) > > > + return err; > > > + > > > + err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); > > > + btf__free(btf); > > > + if (err <= 0) > > > + return err; > > > + > > > + return err; > > > +} > > > + > > > +int load_fentry(int attach_prog_fd, int attach_btf_id) > > static > > Thx! > > > > +{ > > > + LIBBPF_OPTS(bpf_prog_load_opts, opts, > > > + .expected_attach_type = BPF_TRACE_FENTRY, > > > + .attach_prog_fd = attach_prog_fd, > > > + .attach_btf_id = attach_btf_id, > > > + .log_buf = bpf_log_buf, > > > + .log_size = sizeof(bpf_log_buf), > > > + ); > > > + struct bpf_insn insns[] = { > > > + BPF_MOV64_IMM(BPF_REG_0, 0), > > > + BPF_EXIT_INSN(), > > > + }; > > > + int ret; > > > + > > > + ret = bpf_prog_load(BPF_PROG_TYPE_TRACING, > > > + "bind4_fentry", > > > + "GPL", > > > + insns, > > > + ARRAY_SIZE(insns), > > > + &opts); > > > + if (ret) > > > + printf("verifier log: %s\n", bpf_log_buf); > > If this fentry prog is in the attach_to_bpf.c and load by skel, this printf > > and the bpf_log_buf can go away. I wonder if it can use the '?' like > > SEC("?cgroup/bind4") and SEC("?fentry"). Then opens attach_to_bpf.skel.h > > twice and use bpf_program__set_autoload() to load individual program . > > Good ideal, let me try to see if doing "?fentry" is easier.. > (unless we agree to keep load_fentry, see below) > > > Another option could be to reuse the progs/bind4_prog.c and directly > > put the fentry program in the attach_to_bpf.c. > > > > btw, this test feels like something that could be a few line > > addition to the test_fexit_bpf2bpf_common() in fexit_bpf2bpf.c. > > Adding one to test fentry into a cgroup bpf prog is also good. > > No strong opinion here also. > > I was trying to reuse fexit_bpf2bpf initially but I sank too much time > into it and decided that it might be easier to write a > simpler/separate reproducer instead :-( > How about we reuse progs/bind4_prog.c and keep load_fentry() ? And put > this new test in fexit_bpf2bpf.c ? Reusing bind4_prog.c sounds good. Either use bind4_prog.c in the new prog_tests/attach_to_bpf.c (likely need a better name) or the fexit_bpf2bpf.c is fine. Whatever makes more sense. I was mostly thinking to avoid the special verifier log buf handling and the printf here. If an empty fentry prog may look weird, may be just skip the bpf_log_buf and printf since it will never fail and keep the load_fentry ?
diff --git a/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c new file mode 100644 index 000000000000..fcf726c5ff0f --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c @@ -0,0 +1,109 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include <stdlib.h> +#include <bpf/btf.h> +#include <test_progs.h> +#include <network_helpers.h> +#include "attach_to_bpf.skel.h" + +char bpf_log_buf[BPF_LOG_BUF_SIZE]; + +static int find_prog_btf_id(const char *name, __u32 attach_prog_fd) +{ + struct bpf_prog_info info = {}; + __u32 info_len = sizeof(info); + struct btf *btf; + int err; + + err = bpf_obj_get_info_by_fd(attach_prog_fd, &info, &info_len); + if (err) + return err; + + if (!info.btf_id) + return -EINVAL; + + btf = btf__load_from_kernel_by_id(info.btf_id); + err = libbpf_get_error(btf); + if (err) + return err; + + err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); + btf__free(btf); + if (err <= 0) + return err; + + return err; +} + +int load_fentry(int attach_prog_fd, int attach_btf_id) +{ + LIBBPF_OPTS(bpf_prog_load_opts, opts, + .expected_attach_type = BPF_TRACE_FENTRY, + .attach_prog_fd = attach_prog_fd, + .attach_btf_id = attach_btf_id, + .log_buf = bpf_log_buf, + .log_size = sizeof(bpf_log_buf), + ); + struct bpf_insn insns[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + int ret; + + ret = bpf_prog_load(BPF_PROG_TYPE_TRACING, + "bind4_fentry", + "GPL", + insns, + ARRAY_SIZE(insns), + &opts); + if (ret) + printf("verifier log: %s\n", bpf_log_buf); + return ret; +} + +void test_attach_to_bpf(void) +{ + struct attach_to_bpf *skel = NULL; + struct bpf_prog_info info = {}; + __u32 info_len = sizeof(info); + int cgroup_fd = -1; + int fentry_fd = -1; + int btf_id; + + cgroup_fd = test__join_cgroup("/attach_to_bpf"); + if (!ASSERT_GE(cgroup_fd, 0, "cgroup_fd")) + return; + + skel = attach_to_bpf__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel")) + goto cleanup; + + skel->links.bind4 = bpf_program__attach_cgroup(skel->progs.bind4, cgroup_fd); + if (!ASSERT_OK_PTR(skel, "bpf_program__attach_cgroup")) + goto cleanup; + + btf_id = find_prog_btf_id("bind4", bpf_program__fd(skel->progs.bind4)); + if (!ASSERT_GE(btf_id, 0, "find_prog_btf_id")) + goto cleanup; + + fentry_fd = load_fentry(bpf_program__fd(skel->progs.bind4), btf_id); + if (!ASSERT_GE(fentry_fd, 0, "load_fentry")) + goto cleanup; + + /* Make sure bpf_obj_get_info_by_fd works correctly when attaching + * to another BPF program. + */ + + if (!ASSERT_OK(bpf_obj_get_info_by_fd(fentry_fd, &info, &info_len), + "bpf_obj_get_info_by_fd")) + goto cleanup; + + ASSERT_EQ(info.btf_id, 0, "info.btf_id"); + ASSERT_GT(info.attach_btf_id, 0, "info.attach_btf_id"); + ASSERT_GT(info.attach_btf_obj_id, 0, "info.attach_btf_obj_id"); + +cleanup: + close(cgroup_fd); + close(fentry_fd); + attach_to_bpf__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/attach_to_bpf.c b/tools/testing/selftests/bpf/progs/attach_to_bpf.c new file mode 100644 index 000000000000..3f111fe96f8f --- /dev/null +++ b/tools/testing/selftests/bpf/progs/attach_to_bpf.c @@ -0,0 +1,12 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/bpf.h> +#include <bpf/bpf_helpers.h> + +SEC("cgroup/bind4") +int bind4(struct bpf_sock_addr *ctx) +{ + return 1; +} + +char _license[] SEC("license") = "GPL";
Apparently, no existing selftest covers it. Add a new one where we load cgroup/bind4 program and attach fentry to it. Calling bpf_obj_get_info_by_fd on the fentry program should return non-zero btf_id/btf_obj_id instead of crashing the kernel. Signed-off-by: Stanislav Fomichev <sdf@google.com> --- .../selftests/bpf/prog_tests/attach_to_bpf.c | 109 ++++++++++++++++++ .../selftests/bpf/progs/attach_to_bpf.c | 12 ++ 2 files changed, 121 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c create mode 100644 tools/testing/selftests/bpf/progs/attach_to_bpf.c