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Date: Thu, 16 Jul 2020 13:14:41 +0300
From: Dan Carpenter <dan.carpenter@...cle.com>
To: kbuild@...ts.01.org,
Toke Høiland-Jørgensen <toke@...hat.com>,
Alexei Starovoitov <ast@...nel.org>
Cc: lkp@...el.com, kbuild-all@...ts.01.org,
Daniel Borkmann <daniel@...earbox.net>,
Martin KaFai Lau <kafai@...com>,
Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
Andrii Nakryiko <andriin@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...omium.org>, netdev@...r.kernel.org,
bpf@...r.kernel.org
Subject: Re: [PATCH bpf-next v2 3/6] bpf: support attaching freplace programs
to multiple attach points
Hi Toke,
url: https://github.com/0day-ci/linux/commits/Toke-H-iland-J-rgensen/bpf-Support-multi-attach-for-freplace-programs/20200715-211145
base: https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: x86_64-randconfig-m001-20200715 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-14) 9.3.0
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
New smatch warnings:
kernel/bpf/verifier.c:10900 bpf_check_attach_target() error: we previously assumed 'tgt_prog' could be null (see line 10772)
Old smatch warnings:
include/linux/bpf_verifier.h:351 bpf_verifier_log_needed() error: we previously assumed 'log' could be null (see line 350)
# https://github.com/0day-ci/linux/commit/cc8571ec751a3a6065838e0b15105f8be0ced6fe
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout cc8571ec751a3a6065838e0b15105f8be0ced6fe
vim +/tgt_prog +10900 kernel/bpf/verifier.c
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10734 int bpf_check_attach_target(struct bpf_verifier_log *log,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10735 const struct bpf_prog *prog,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10736 const struct bpf_prog *tgt_prog,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10737 u32 btf_id,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10738 struct btf_func_model *fmodel,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10739 long *tgt_addr,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10740 const char **tgt_name,
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10741 const struct btf_type **tgt_type)
38207291604401 Martin KaFai Lau 2019-10-24 10742 {
be8704ff07d237 Alexei Starovoitov 2020-01-20 10743 bool prog_extension = prog->type == BPF_PROG_TYPE_EXT;
f1b9509c2fb0ef Alexei Starovoitov 2019-10-30 10744 const char prefix[] = "btf_trace_";
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10745 int ret = 0, subprog = -1, i;
38207291604401 Martin KaFai Lau 2019-10-24 10746 const struct btf_type *t;
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10747 bool conservative = true;
38207291604401 Martin KaFai Lau 2019-10-24 10748 const char *tname;
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10749 struct btf *btf;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10750 long addr = 0;
38207291604401 Martin KaFai Lau 2019-10-24 10751
f1b9509c2fb0ef Alexei Starovoitov 2019-10-30 10752 if (!btf_id) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10753 bpf_log(log, "Tracing programs must provide btf_id\n");
f1b9509c2fb0ef Alexei Starovoitov 2019-10-30 10754 return -EINVAL;
f1b9509c2fb0ef Alexei Starovoitov 2019-10-30 10755 }
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10756 btf = bpf_prog_get_target_btf(prog);
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10757 if (!btf) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10758 bpf_log(log,
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10759 "FENTRY/FEXIT program can only be attached to another program annotated with BTF\n");
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10760 return -EINVAL;
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10761 }
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10762 t = btf_type_by_id(btf, btf_id);
38207291604401 Martin KaFai Lau 2019-10-24 10763 if (!t) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10764 bpf_log(log, "attach_btf_id %u is invalid\n", btf_id);
38207291604401 Martin KaFai Lau 2019-10-24 10765 return -EINVAL;
38207291604401 Martin KaFai Lau 2019-10-24 10766 }
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10767 tname = btf_name_by_offset(btf, t->name_off);
f1b9509c2fb0ef Alexei Starovoitov 2019-10-30 10768 if (!tname) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10769 bpf_log(log, "attach_btf_id %u doesn't have a name\n", btf_id);
f1b9509c2fb0ef Alexei Starovoitov 2019-10-30 10770 return -EINVAL;
f1b9509c2fb0ef Alexei Starovoitov 2019-10-30 10771 }
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 @10772 if (tgt_prog) {
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10773 struct bpf_prog_aux *aux = tgt_prog->aux;
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10774
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10775 for (i = 0; i < aux->func_info_cnt; i++)
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10776 if (aux->func_info[i].type_id == btf_id) {
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10777 subprog = i;
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10778 break;
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10779 }
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10780 if (subprog == -1) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10781 bpf_log(log, "Subprog %s doesn't exist\n", tname);
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10782 return -EINVAL;
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10783 }
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10784 conservative = aux->func_info_aux[subprog].unreliable;
be8704ff07d237 Alexei Starovoitov 2020-01-20 10785 if (prog_extension) {
be8704ff07d237 Alexei Starovoitov 2020-01-20 10786 if (conservative) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10787 bpf_log(log,
be8704ff07d237 Alexei Starovoitov 2020-01-20 10788 "Cannot replace static functions\n");
be8704ff07d237 Alexei Starovoitov 2020-01-20 10789 return -EINVAL;
be8704ff07d237 Alexei Starovoitov 2020-01-20 10790 }
be8704ff07d237 Alexei Starovoitov 2020-01-20 10791 if (!prog->jit_requested) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10792 bpf_log(log,
be8704ff07d237 Alexei Starovoitov 2020-01-20 10793 "Extension programs should be JITed\n");
be8704ff07d237 Alexei Starovoitov 2020-01-20 10794 return -EINVAL;
be8704ff07d237 Alexei Starovoitov 2020-01-20 10795 }
be8704ff07d237 Alexei Starovoitov 2020-01-20 10796 }
be8704ff07d237 Alexei Starovoitov 2020-01-20 10797 if (!tgt_prog->jited) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10798 bpf_log(log, "Can attach to only JITed progs\n");
be8704ff07d237 Alexei Starovoitov 2020-01-20 10799 return -EINVAL;
be8704ff07d237 Alexei Starovoitov 2020-01-20 10800 }
be8704ff07d237 Alexei Starovoitov 2020-01-20 10801 if (tgt_prog->type == prog->type) {
be8704ff07d237 Alexei Starovoitov 2020-01-20 10802 /* Cannot fentry/fexit another fentry/fexit program.
be8704ff07d237 Alexei Starovoitov 2020-01-20 10803 * Cannot attach program extension to another extension.
be8704ff07d237 Alexei Starovoitov 2020-01-20 10804 * It's ok to attach fentry/fexit to extension program.
be8704ff07d237 Alexei Starovoitov 2020-01-20 10805 */
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10806 bpf_log(log, "Cannot recursively attach\n");
be8704ff07d237 Alexei Starovoitov 2020-01-20 10807 return -EINVAL;
be8704ff07d237 Alexei Starovoitov 2020-01-20 10808 }
be8704ff07d237 Alexei Starovoitov 2020-01-20 10809 if (tgt_prog->type == BPF_PROG_TYPE_TRACING &&
be8704ff07d237 Alexei Starovoitov 2020-01-20 10810 prog_extension &&
be8704ff07d237 Alexei Starovoitov 2020-01-20 10811 (tgt_prog->expected_attach_type == BPF_TRACE_FENTRY ||
be8704ff07d237 Alexei Starovoitov 2020-01-20 10812 tgt_prog->expected_attach_type == BPF_TRACE_FEXIT)) {
be8704ff07d237 Alexei Starovoitov 2020-01-20 10813 /* Program extensions can extend all program types
be8704ff07d237 Alexei Starovoitov 2020-01-20 10814 * except fentry/fexit. The reason is the following.
be8704ff07d237 Alexei Starovoitov 2020-01-20 10815 * The fentry/fexit programs are used for performance
be8704ff07d237 Alexei Starovoitov 2020-01-20 10816 * analysis, stats and can be attached to any program
be8704ff07d237 Alexei Starovoitov 2020-01-20 10817 * type except themselves. When extension program is
be8704ff07d237 Alexei Starovoitov 2020-01-20 10818 * replacing XDP function it is necessary to allow
be8704ff07d237 Alexei Starovoitov 2020-01-20 10819 * performance analysis of all functions. Both original
be8704ff07d237 Alexei Starovoitov 2020-01-20 10820 * XDP program and its program extension. Hence
be8704ff07d237 Alexei Starovoitov 2020-01-20 10821 * attaching fentry/fexit to BPF_PROG_TYPE_EXT is
be8704ff07d237 Alexei Starovoitov 2020-01-20 10822 * allowed. If extending of fentry/fexit was allowed it
be8704ff07d237 Alexei Starovoitov 2020-01-20 10823 * would be possible to create long call chain
be8704ff07d237 Alexei Starovoitov 2020-01-20 10824 * fentry->extension->fentry->extension beyond
be8704ff07d237 Alexei Starovoitov 2020-01-20 10825 * reasonable stack size. Hence extending fentry is not
be8704ff07d237 Alexei Starovoitov 2020-01-20 10826 * allowed.
be8704ff07d237 Alexei Starovoitov 2020-01-20 10827 */
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10828 bpf_log(log, "Cannot extend fentry/fexit\n");
be8704ff07d237 Alexei Starovoitov 2020-01-20 10829 return -EINVAL;
be8704ff07d237 Alexei Starovoitov 2020-01-20 10830 }
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10831 } else {
be8704ff07d237 Alexei Starovoitov 2020-01-20 10832 if (prog_extension) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10833 bpf_log(log, "Cannot replace kernel functions\n");
be8704ff07d237 Alexei Starovoitov 2020-01-20 10834 return -EINVAL;
be8704ff07d237 Alexei Starovoitov 2020-01-20 10835 }
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10836 }
f1b9509c2fb0ef Alexei Starovoitov 2019-10-30 10837
f1b9509c2fb0ef Alexei Starovoitov 2019-10-30 10838 switch (prog->expected_attach_type) {
f1b9509c2fb0ef Alexei Starovoitov 2019-10-30 10839 case BPF_TRACE_RAW_TP:
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10840 if (tgt_prog) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10841 bpf_log(log,
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10842 "Only FENTRY/FEXIT progs are attachable to another BPF prog\n");
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10843 return -EINVAL;
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10844 }
38207291604401 Martin KaFai Lau 2019-10-24 10845 if (!btf_type_is_typedef(t)) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10846 bpf_log(log, "attach_btf_id %u is not a typedef\n",
38207291604401 Martin KaFai Lau 2019-10-24 10847 btf_id);
38207291604401 Martin KaFai Lau 2019-10-24 10848 return -EINVAL;
38207291604401 Martin KaFai Lau 2019-10-24 10849 }
f1b9509c2fb0ef Alexei Starovoitov 2019-10-30 10850 if (strncmp(prefix, tname, sizeof(prefix) - 1)) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10851 bpf_log(log, "attach_btf_id %u points to wrong type name %s\n",
38207291604401 Martin KaFai Lau 2019-10-24 10852 btf_id, tname);
38207291604401 Martin KaFai Lau 2019-10-24 10853 return -EINVAL;
38207291604401 Martin KaFai Lau 2019-10-24 10854 }
38207291604401 Martin KaFai Lau 2019-10-24 10855 tname += sizeof(prefix) - 1;
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10856 t = btf_type_by_id(btf, t->type);
38207291604401 Martin KaFai Lau 2019-10-24 10857 if (!btf_type_is_ptr(t))
38207291604401 Martin KaFai Lau 2019-10-24 10858 /* should never happen in valid vmlinux build */
38207291604401 Martin KaFai Lau 2019-10-24 10859 return -EINVAL;
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10860 t = btf_type_by_id(btf, t->type);
38207291604401 Martin KaFai Lau 2019-10-24 10861 if (!btf_type_is_func_proto(t))
38207291604401 Martin KaFai Lau 2019-10-24 10862 /* should never happen in valid vmlinux build */
38207291604401 Martin KaFai Lau 2019-10-24 10863 return -EINVAL;
38207291604401 Martin KaFai Lau 2019-10-24 10864
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10865 break;
15d83c4d7cef5c Yonghong Song 2020-05-09 10866 case BPF_TRACE_ITER:
15d83c4d7cef5c Yonghong Song 2020-05-09 10867 if (!btf_type_is_func(t)) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10868 bpf_log(log, "attach_btf_id %u is not a function\n",
15d83c4d7cef5c Yonghong Song 2020-05-09 10869 btf_id);
15d83c4d7cef5c Yonghong Song 2020-05-09 10870 return -EINVAL;
15d83c4d7cef5c Yonghong Song 2020-05-09 10871 }
15d83c4d7cef5c Yonghong Song 2020-05-09 10872 t = btf_type_by_id(btf, t->type);
15d83c4d7cef5c Yonghong Song 2020-05-09 10873 if (!btf_type_is_func_proto(t))
15d83c4d7cef5c Yonghong Song 2020-05-09 10874 return -EINVAL;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10875 ret = btf_distill_func_proto(log, btf, t, tname, fmodel);
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10876 if (ret)
15d83c4d7cef5c Yonghong Song 2020-05-09 10877 return ret;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10878 break;
be8704ff07d237 Alexei Starovoitov 2020-01-20 10879 default:
be8704ff07d237 Alexei Starovoitov 2020-01-20 10880 if (!prog_extension)
be8704ff07d237 Alexei Starovoitov 2020-01-20 10881 return -EINVAL;
be8704ff07d237 Alexei Starovoitov 2020-01-20 10882 /* fallthrough */
ae24082331d9bb KP Singh 2020-03-04 10883 case BPF_MODIFY_RETURN:
9e4e01dfd3254c KP Singh 2020-03-29 10884 case BPF_LSM_MAC:
fec56f5890d93f Alexei Starovoitov 2019-11-14 10885 case BPF_TRACE_FENTRY:
fec56f5890d93f Alexei Starovoitov 2019-11-14 10886 case BPF_TRACE_FEXIT:
fec56f5890d93f Alexei Starovoitov 2019-11-14 10887 if (!btf_type_is_func(t)) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10888 bpf_log(log, "attach_btf_id %u is not a function\n",
fec56f5890d93f Alexei Starovoitov 2019-11-14 10889 btf_id);
fec56f5890d93f Alexei Starovoitov 2019-11-14 10890 return -EINVAL;
fec56f5890d93f Alexei Starovoitov 2019-11-14 10891 }
be8704ff07d237 Alexei Starovoitov 2020-01-20 10892 if (prog_extension &&
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10893 btf_check_type_match(log, prog, btf, t))
be8704ff07d237 Alexei Starovoitov 2020-01-20 10894 return -EINVAL;
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10895 t = btf_type_by_id(btf, t->type);
fec56f5890d93f Alexei Starovoitov 2019-11-14 10896 if (!btf_type_is_func_proto(t))
fec56f5890d93f Alexei Starovoitov 2019-11-14 10897 return -EINVAL;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10898
cc8571ec751a3a Toke Høiland-Jørgensen 2020-07-15 10899 if ((prog->aux->tgt_prog_type &&
cc8571ec751a3a Toke Høiland-Jørgensen 2020-07-15 @10900 prog->aux->tgt_prog_type != tgt_prog->type) ||
^^^^^^^^^^^^^^
cc8571ec751a3a Toke Høiland-Jørgensen 2020-07-15 10901 (prog->aux->tgt_attach_type &&
cc8571ec751a3a Toke Høiland-Jørgensen 2020-07-15 10902 prog->aux->tgt_attach_type != tgt_prog->expected_attach_type))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Not checked.
cc8571ec751a3a Toke Høiland-Jørgensen 2020-07-15 10903 return -EINVAL;
cc8571ec751a3a Toke Høiland-Jørgensen 2020-07-15 10904
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10905 if (tgt_prog && conservative)
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10906 t = NULL;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10907
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10908 ret = btf_distill_func_proto(log, btf, t, tname, fmodel);
fec56f5890d93f Alexei Starovoitov 2019-11-14 10909 if (ret < 0)
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10910 return ret;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10911
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10912 if (tgt_prog) {
e9eeec58c992c4 Yonghong Song 2019-12-04 10913 if (subprog == 0)
e9eeec58c992c4 Yonghong Song 2019-12-04 10914 addr = (long) tgt_prog->bpf_func;
e9eeec58c992c4 Yonghong Song 2019-12-04 10915 else
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10916 addr = (long) tgt_prog->aux->func[subprog]->bpf_func;
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10917 } else {
fec56f5890d93f Alexei Starovoitov 2019-11-14 10918 addr = kallsyms_lookup_name(tname);
fec56f5890d93f Alexei Starovoitov 2019-11-14 10919 if (!addr) {
e33243ff1dd2cb Toke Høiland-Jørgensen 2020-07-15 10920 bpf_log(log,
fec56f5890d93f Alexei Starovoitov 2019-11-14 10921 "The address of function %s cannot be found\n",
fec56f5890d93f Alexei Starovoitov 2019-11-14 10922 tname);
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10923 return -ENOENT;
fec56f5890d93f Alexei Starovoitov 2019-11-14 10924 }
5b92a28aae4dd0 Alexei Starovoitov 2019-11-14 10925 }
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10926 break;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10927 }
18644cec714aab Alexei Starovoitov 2020-05-28 10928
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10929 *tgt_addr = addr;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10930 if (tgt_name)
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10931 *tgt_name = tname;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10932 if (tgt_type)
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10933 *tgt_type = t;
c2d0f6ffe7709e Toke Høiland-Jørgensen 2020-07-15 10934 return 0;
18644cec714aab Alexei Starovoitov 2020-05-28 10935 }
---
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