| Message ID | 20220801173926.2441748-2-sdf@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | BPF |
| Headers | show |
| Series | [bpf-next,v2,1/2] bpf: use proper target btf when exporting attach_btf_obj_id | expand |
On Mon, Aug 1, 2022 at 10:39 AM 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. > > v2: > - use ret instead of err in find_prog_btf_id (Hao) > - remove verifier log (Hao) > - drop if conditional from ASSERT_OK(bpf_obj_get_info_by_fd(...)) (Hao) > > Signed-off-by: Stanislav Fomichev <sdf@google.com> I see Martin has comments based on v1, but v2 looks good to me. Acked-by: Hao Luo <haoluo@google.com> > --- > .../selftests/bpf/prog_tests/attach_to_bpf.c | 97 +++++++++++++++++++ > .../selftests/bpf/progs/attach_to_bpf.c | 12 +++ > 2 files changed, 109 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..eb06f522c0b3 > --- /dev/null > +++ b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c > @@ -0,0 +1,97 @@ > +// 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" > + > +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 ret; > + > + ret = bpf_obj_get_info_by_fd(attach_prog_fd, &info, &info_len); > + if (ret) > + return ret; > + > + if (!info.btf_id) > + return -EINVAL; > + > + btf = btf__load_from_kernel_by_id(info.btf_id); > + ret = libbpf_get_error(btf); > + if (ret) > + return ret; > + > + ret = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); > + btf__free(btf); > + return ret; > +} > + > +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, > + ); > + struct bpf_insn insns[] = { > + BPF_MOV64_IMM(BPF_REG_0, 0), > + BPF_EXIT_INSN(), > + }; > + > + return bpf_prog_load(BPF_PROG_TYPE_TRACING, > + "bind4_fentry", > + "GPL", > + insns, > + ARRAY_SIZE(insns), > + &opts); > +} > + > +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. > + */ > + > + ASSERT_OK(bpf_obj_get_info_by_fd(fentry_fd, &info, &info_len), > + "bpf_obj_get_info_by_fd"); > + > + 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 Mon, Aug 1, 2022 at 10:39 AM 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. > > v2: > - use ret instead of err in find_prog_btf_id (Hao) > - remove verifier log (Hao) > - drop if conditional from ASSERT_OK(bpf_obj_get_info_by_fd(...)) (Hao) > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > --- > .../selftests/bpf/prog_tests/attach_to_bpf.c | 97 +++++++++++++++++++ > .../selftests/bpf/progs/attach_to_bpf.c | 12 +++ > 2 files changed, 109 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 > [...] > + > + ret = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); > + btf__free(btf); > + return ret; > +} > + > +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, > + ); > + struct bpf_insn insns[] = { > + BPF_MOV64_IMM(BPF_REG_0, 0), > + BPF_EXIT_INSN(), > + }; > + > + return bpf_prog_load(BPF_PROG_TYPE_TRACING, > + "bind4_fentry", > + "GPL", > + insns, > + ARRAY_SIZE(insns), > + &opts); > +} > + > +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")) you probably meant to check skel->links.bind4 instead of just skel (which you already checked) > + 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. > + */ > + > + ASSERT_OK(bpf_obj_get_info_by_fd(fentry_fd, &info, &info_len), > + "bpf_obj_get_info_by_fd"); > + > + 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: if (cgroup_fd >= 0) > + close(cgroup_fd); if (fentry_fd >= 0) > + 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 Mon, Aug 1, 2022 at 2:44 PM Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: > > On Mon, Aug 1, 2022 at 10:39 AM 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. > > > > v2: > > - use ret instead of err in find_prog_btf_id (Hao) > > - remove verifier log (Hao) > > - drop if conditional from ASSERT_OK(bpf_obj_get_info_by_fd(...)) (Hao) > > > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > > --- > > .../selftests/bpf/prog_tests/attach_to_bpf.c | 97 +++++++++++++++++++ > > .../selftests/bpf/progs/attach_to_bpf.c | 12 +++ > > 2 files changed, 109 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 > > > > [...] > > > + > > + ret = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); > > + btf__free(btf); > > + return ret; > > +} > > + > > +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, > > + ); > > + struct bpf_insn insns[] = { > > + BPF_MOV64_IMM(BPF_REG_0, 0), > > + BPF_EXIT_INSN(), > > + }; > > + > > + return bpf_prog_load(BPF_PROG_TYPE_TRACING, > > + "bind4_fentry", > > + "GPL", > > + insns, > > + ARRAY_SIZE(insns), > > + &opts); > > +} > > + > > +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")) > > you probably meant to check skel->links.bind4 instead of just skel > (which you already checked) Oh, good catch, thanks! > > + 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. > > + */ > > + > > + ASSERT_OK(bpf_obj_get_info_by_fd(fentry_fd, &info, &info_len), > > + "bpf_obj_get_info_by_fd"); > > + > > + 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: > > if (cgroup_fd >= 0) > > > + close(cgroup_fd); > > if (fentry_fd >= 0) Should be safe to do unconditional close(-1), right? Why bother with the checks here? Seems like a common pattern we do elsewhere? > > + 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 Mon, Aug 1, 2022 at 12:34 PM Hao Luo <haoluo@google.com> wrote: > > On Mon, Aug 1, 2022 at 10:39 AM 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. > > > > v2: > > - use ret instead of err in find_prog_btf_id (Hao) > > - remove verifier log (Hao) > > - drop if conditional from ASSERT_OK(bpf_obj_get_info_by_fd(...)) (Hao) > > > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > > I see Martin has comments based on v1, but v2 looks good to me. > > Acked-by: Hao Luo <haoluo@google.com> Thank you for the review! I'll move some stuff around for v3, so I'll have to ask you to have one more :-(
On Tue, Aug 2, 2022 at 9:21 AM Stanislav Fomichev <sdf@google.com> wrote: > > On Mon, Aug 1, 2022 at 2:44 PM Andrii Nakryiko > <andrii.nakryiko@gmail.com> wrote: > > > > On Mon, Aug 1, 2022 at 10:39 AM 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. > > > > > > v2: > > > - use ret instead of err in find_prog_btf_id (Hao) > > > - remove verifier log (Hao) > > > - drop if conditional from ASSERT_OK(bpf_obj_get_info_by_fd(...)) (Hao) > > > > > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > > > --- > > > .../selftests/bpf/prog_tests/attach_to_bpf.c | 97 +++++++++++++++++++ > > > .../selftests/bpf/progs/attach_to_bpf.c | 12 +++ > > > 2 files changed, 109 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 > > > > > > > [...] > > > > > + > > > + ret = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); > > > + btf__free(btf); > > > + return ret; > > > +} > > > + > > > +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, > > > + ); > > > + struct bpf_insn insns[] = { > > > + BPF_MOV64_IMM(BPF_REG_0, 0), > > > + BPF_EXIT_INSN(), > > > + }; > > > + > > > + return bpf_prog_load(BPF_PROG_TYPE_TRACING, > > > + "bind4_fentry", > > > + "GPL", > > > + insns, > > > + ARRAY_SIZE(insns), > > > + &opts); > > > +} > > > + > > > +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")) > > > > you probably meant to check skel->links.bind4 instead of just skel > > (which you already checked) > > Oh, good catch, thanks! > > > > + 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. > > > + */ > > > + > > > + ASSERT_OK(bpf_obj_get_info_by_fd(fentry_fd, &info, &info_len), > > > + "bpf_obj_get_info_by_fd"); > > > + > > > + 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: > > > > if (cgroup_fd >= 0) > > > > > + close(cgroup_fd); > > > > if (fentry_fd >= 0) > > Should be safe to do unconditional close(-1), right? Why bother with > the checks here? Seems like a common pattern we do elsewhere? > I don't think we consciously do close(-1), libbpf definitely tries hard to not attempt to close invalid fd, and so do (most?) of selftests. Where do you see use doing close(-1)? > > > + 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 Tue, Aug 2, 2022 at 11:42 AM Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: > > On Tue, Aug 2, 2022 at 9:21 AM Stanislav Fomichev <sdf@google.com> wrote: > > > > On Mon, Aug 1, 2022 at 2:44 PM Andrii Nakryiko > > <andrii.nakryiko@gmail.com> wrote: > > > > > > On Mon, Aug 1, 2022 at 10:39 AM 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. > > > > > > > > v2: > > > > - use ret instead of err in find_prog_btf_id (Hao) > > > > - remove verifier log (Hao) > > > > - drop if conditional from ASSERT_OK(bpf_obj_get_info_by_fd(...)) (Hao) > > > > > > > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > > > > --- > > > > .../selftests/bpf/prog_tests/attach_to_bpf.c | 97 +++++++++++++++++++ > > > > .../selftests/bpf/progs/attach_to_bpf.c | 12 +++ > > > > 2 files changed, 109 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 > > > > > > > > > > [...] > > > > > > > + > > > > + ret = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); > > > > + btf__free(btf); > > > > + return ret; > > > > +} > > > > + > > > > +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, > > > > + ); > > > > + struct bpf_insn insns[] = { > > > > + BPF_MOV64_IMM(BPF_REG_0, 0), > > > > + BPF_EXIT_INSN(), > > > > + }; > > > > + > > > > + return bpf_prog_load(BPF_PROG_TYPE_TRACING, > > > > + "bind4_fentry", > > > > + "GPL", > > > > + insns, > > > > + ARRAY_SIZE(insns), > > > > + &opts); > > > > +} > > > > + > > > > +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")) > > > > > > you probably meant to check skel->links.bind4 instead of just skel > > > (which you already checked) > > > > Oh, good catch, thanks! > > > > > > + 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. > > > > + */ > > > > + > > > > + ASSERT_OK(bpf_obj_get_info_by_fd(fentry_fd, &info, &info_len), > > > > + "bpf_obj_get_info_by_fd"); > > > > + > > > > + 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: > > > > > > if (cgroup_fd >= 0) > > > > > > > + close(cgroup_fd); > > > > > > if (fentry_fd >= 0) > > > > Should be safe to do unconditional close(-1), right? Why bother with > > the checks here? Seems like a common pattern we do elsewhere? > > > > I don't think we consciously do close(-1), libbpf definitely tries > hard to not attempt to close invalid fd, and so do (most?) of > selftests. Where do you see use doing close(-1)? I might have contributed to this :-/ Everything is from prog_tests: sockopt_multi.c (test_sockopt_multi) lsm_cgroup.c (test_lsm_cgroup_functional) But there is more that haven't been added by me: d_path.c (trigger_fstat_events) cgroup_attach_override.c (serial_test_cgroup_attach_override) cg_storage_multi.c (connect_send) test_local_storage.c (test_test_local_storage) bpf_cookie.c (kprobe_multi_link_api_subtest) fexit_bpf2bpf.c (test_fentry_to_cgroup_bpf) (I stopped here, maybe there is more?) I'm not sure how much we should care about these 'if (fd >= 0)' checks. It might be it's easier to always do close(-1), otherwise we get bugs like the one in test_unpriv_bpf_disabled_positive from unpriv_bpf_disabled.c: if (link_fd) close(link_fd); (but I'm also happy to add those 'ifs' if you prefer, lmk) ? > > > > + 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 Tue, Aug 2, 2022 at 1:53 PM Stanislav Fomichev <sdf@google.com> wrote: > > On Tue, Aug 2, 2022 at 11:42 AM Andrii Nakryiko > <andrii.nakryiko@gmail.com> wrote: > > > > On Tue, Aug 2, 2022 at 9:21 AM Stanislav Fomichev <sdf@google.com> wrote: > > > > > > On Mon, Aug 1, 2022 at 2:44 PM Andrii Nakryiko > > > <andrii.nakryiko@gmail.com> wrote: > > > > > > > > On Mon, Aug 1, 2022 at 10:39 AM 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. > > > > > > > > > > v2: > > > > > - use ret instead of err in find_prog_btf_id (Hao) > > > > > - remove verifier log (Hao) > > > > > - drop if conditional from ASSERT_OK(bpf_obj_get_info_by_fd(...)) (Hao) > > > > > > > > > > Signed-off-by: Stanislav Fomichev <sdf@google.com> > > > > > --- > > > > > .../selftests/bpf/prog_tests/attach_to_bpf.c | 97 +++++++++++++++++++ > > > > > .../selftests/bpf/progs/attach_to_bpf.c | 12 +++ > > > > > 2 files changed, 109 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 > > > > > > > > > > > > > [...] > > > > > > > > > + > > > > > + ret = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); > > > > > + btf__free(btf); > > > > > + return ret; > > > > > +} > > > > > + > > > > > +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, > > > > > + ); > > > > > + struct bpf_insn insns[] = { > > > > > + BPF_MOV64_IMM(BPF_REG_0, 0), > > > > > + BPF_EXIT_INSN(), > > > > > + }; > > > > > + > > > > > + return bpf_prog_load(BPF_PROG_TYPE_TRACING, > > > > > + "bind4_fentry", > > > > > + "GPL", > > > > > + insns, > > > > > + ARRAY_SIZE(insns), > > > > > + &opts); > > > > > +} > > > > > + > > > > > +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")) > > > > > > > > you probably meant to check skel->links.bind4 instead of just skel > > > > (which you already checked) > > > > > > Oh, good catch, thanks! > > > > > > > > + 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. > > > > > + */ > > > > > + > > > > > + ASSERT_OK(bpf_obj_get_info_by_fd(fentry_fd, &info, &info_len), > > > > > + "bpf_obj_get_info_by_fd"); > > > > > + > > > > > + 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: > > > > > > > > if (cgroup_fd >= 0) > > > > > > > > > + close(cgroup_fd); > > > > > > > > if (fentry_fd >= 0) > > > > > > Should be safe to do unconditional close(-1), right? Why bother with > > > the checks here? Seems like a common pattern we do elsewhere? > > > > > > > I don't think we consciously do close(-1), libbpf definitely tries > > hard to not attempt to close invalid fd, and so do (most?) of > > selftests. Where do you see use doing close(-1)? > > I might have contributed to this :-/ Everything is from prog_tests: > sockopt_multi.c (test_sockopt_multi) > lsm_cgroup.c (test_lsm_cgroup_functional) > > But there is more that haven't been added by me: > d_path.c (trigger_fstat_events) > cgroup_attach_override.c (serial_test_cgroup_attach_override) > cg_storage_multi.c (connect_send) > test_local_storage.c (test_test_local_storage) > bpf_cookie.c (kprobe_multi_link_api_subtest) > fexit_bpf2bpf.c (test_fentry_to_cgroup_bpf) > (I stopped here, maybe there is more?) > > I'm not sure how much we should care about these 'if (fd >= 0)' checks. > It might be it's easier to always do close(-1), otherwise we get bugs > like the one in test_unpriv_bpf_disabled_positive from > unpriv_bpf_disabled.c: > if (link_fd) > close(link_fd); > > (but I'm also happy to add those 'ifs' if you prefer, lmk) > > > ? I'd rather have non-sloppy clean up sections. > > > > > > > > + 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 > > > > >
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..eb06f522c0b3 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/attach_to_bpf.c @@ -0,0 +1,97 @@ +// 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" + +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 ret; + + ret = bpf_obj_get_info_by_fd(attach_prog_fd, &info, &info_len); + if (ret) + return ret; + + if (!info.btf_id) + return -EINVAL; + + btf = btf__load_from_kernel_by_id(info.btf_id); + ret = libbpf_get_error(btf); + if (ret) + return ret; + + ret = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC); + btf__free(btf); + return ret; +} + +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, + ); + struct bpf_insn insns[] = { + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + + return bpf_prog_load(BPF_PROG_TYPE_TRACING, + "bind4_fentry", + "GPL", + insns, + ARRAY_SIZE(insns), + &opts); +} + +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. + */ + + ASSERT_OK(bpf_obj_get_info_by_fd(fentry_fd, &info, &info_len), + "bpf_obj_get_info_by_fd"); + + 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. v2: - use ret instead of err in find_prog_btf_id (Hao) - remove verifier log (Hao) - drop if conditional from ASSERT_OK(bpf_obj_get_info_by_fd(...)) (Hao) Signed-off-by: Stanislav Fomichev <sdf@google.com> --- .../selftests/bpf/prog_tests/attach_to_bpf.c | 97 +++++++++++++++++++ .../selftests/bpf/progs/attach_to_bpf.c | 12 +++ 2 files changed, 109 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