| Message ID | 20200427201239.2994896-1-yhs@fb.com |
|---|---|
| State | Changes Requested |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | bpf: implement bpf iterator for kernel data | expand |
On Mon, Apr 27, 2020 at 01:12:39PM -0700, Yonghong Song wrote: > A bpf_iter program is a tracing program with attach type > BPF_TRACE_ITER. The load attribute > attach_btf_id > is used by the verifier against a particular kernel function, > e.g., __bpf_iter__bpf_map in our previous bpf_map iterator. > > The program return value must be 0 for now. In the > future, other return values may be used for filtering or > teminating the iterator. > > Signed-off-by: Yonghong Song <yhs@fb.com> > --- > include/uapi/linux/bpf.h | 1 + > kernel/bpf/verifier.c | 20 ++++++++++++++++++++ > tools/include/uapi/linux/bpf.h | 1 + > 3 files changed, 22 insertions(+) > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index 4a6c47f3febe..f39b9fec37ab 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -215,6 +215,7 @@ enum bpf_attach_type { > BPF_TRACE_FEXIT, > BPF_MODIFY_RETURN, > BPF_LSM_MAC, > + BPF_TRACE_ITER, > __MAX_BPF_ATTACH_TYPE > }; > > diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c > index 91728e0f27eb..fd36c22685d9 100644 > --- a/kernel/bpf/verifier.c > +++ b/kernel/bpf/verifier.c > @@ -7074,6 +7074,11 @@ static int check_return_code(struct bpf_verifier_env *env) > return 0; > range = tnum_const(0); > break; > + case BPF_PROG_TYPE_TRACING: > + if (env->prog->expected_attach_type != BPF_TRACE_ITER) > + return 0; > + range = tnum_const(0); > + break; > default: > return 0; > } > @@ -10454,6 +10459,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) > struct bpf_prog *tgt_prog = prog->aux->linked_prog; > u32 btf_id = prog->aux->attach_btf_id; > const char prefix[] = "btf_trace_"; > + struct btf_func_model fmodel; > int ret = 0, subprog = -1, i; > struct bpf_trampoline *tr; > const struct btf_type *t; > @@ -10595,6 +10601,20 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) > prog->aux->attach_func_proto = t; > prog->aux->attach_btf_trace = true; > return 0; > + case BPF_TRACE_ITER: > + if (!btf_type_is_func(t)) { > + verbose(env, "attach_btf_id %u is not a function\n", > + btf_id); > + return -EINVAL; > + } > + t = btf_type_by_id(btf, t->type); > + if (!btf_type_is_func_proto(t)) Other than the type tests, to ensure the attach_btf_id is a supported bpf_iter target, should the prog be checked against the target list ("struct list_head targets") here also during the prog load time? > + return -EINVAL; > + prog->aux->attach_func_name = tname; > + prog->aux->attach_func_proto = t; > + ret = btf_distill_func_proto(&env->log, btf, t, > + tname, &fmodel); > + return ret; > default: > if (!prog_extension) > return -EINVAL;
On 4/28/20 5:54 PM, Martin KaFai Lau wrote: > On Mon, Apr 27, 2020 at 01:12:39PM -0700, Yonghong Song wrote: >> A bpf_iter program is a tracing program with attach type >> BPF_TRACE_ITER. The load attribute >> attach_btf_id >> is used by the verifier against a particular kernel function, >> e.g., __bpf_iter__bpf_map in our previous bpf_map iterator. >> >> The program return value must be 0 for now. In the >> future, other return values may be used for filtering or >> teminating the iterator. >> >> Signed-off-by: Yonghong Song <yhs@fb.com> >> --- >> include/uapi/linux/bpf.h | 1 + >> kernel/bpf/verifier.c | 20 ++++++++++++++++++++ >> tools/include/uapi/linux/bpf.h | 1 + >> 3 files changed, 22 insertions(+) >> >> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h >> index 4a6c47f3febe..f39b9fec37ab 100644 >> --- a/include/uapi/linux/bpf.h >> +++ b/include/uapi/linux/bpf.h >> @@ -215,6 +215,7 @@ enum bpf_attach_type { >> BPF_TRACE_FEXIT, >> BPF_MODIFY_RETURN, >> BPF_LSM_MAC, >> + BPF_TRACE_ITER, >> __MAX_BPF_ATTACH_TYPE >> }; >> >> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c >> index 91728e0f27eb..fd36c22685d9 100644 >> --- a/kernel/bpf/verifier.c >> +++ b/kernel/bpf/verifier.c >> @@ -7074,6 +7074,11 @@ static int check_return_code(struct bpf_verifier_env *env) >> return 0; >> range = tnum_const(0); >> break; >> + case BPF_PROG_TYPE_TRACING: >> + if (env->prog->expected_attach_type != BPF_TRACE_ITER) >> + return 0; >> + range = tnum_const(0); >> + break; >> default: >> return 0; >> } >> @@ -10454,6 +10459,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) >> struct bpf_prog *tgt_prog = prog->aux->linked_prog; >> u32 btf_id = prog->aux->attach_btf_id; >> const char prefix[] = "btf_trace_"; >> + struct btf_func_model fmodel; >> int ret = 0, subprog = -1, i; >> struct bpf_trampoline *tr; >> const struct btf_type *t; >> @@ -10595,6 +10601,20 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) >> prog->aux->attach_func_proto = t; >> prog->aux->attach_btf_trace = true; >> return 0; >> + case BPF_TRACE_ITER: >> + if (!btf_type_is_func(t)) { >> + verbose(env, "attach_btf_id %u is not a function\n", >> + btf_id); >> + return -EINVAL; >> + } >> + t = btf_type_by_id(btf, t->type); >> + if (!btf_type_is_func_proto(t)) > Other than the type tests, > to ensure the attach_btf_id is a supported bpf_iter target, > should the prog be checked against the target list > ("struct list_head targets") here also during the prog load time? This is a good question. In my RFC v2, I did this, checking against registered targets (essentially, program loading + attaching to the target). In this version, program loading and attaching are separated. - program loading: against btf_id - attaching: linking bpf program to target current linking parameter only bpf_program, but later on there may be additional parameters like map_id, pid, cgroup_id etc. for tailoring the iterator behavior. This seems having a better separation. Agreed that checking at load time may return error earlier instead at link_create time. Let me think about this. > >> + return -EINVAL; >> + prog->aux->attach_func_name = tname; >> + prog->aux->attach_func_proto = t; >> + ret = btf_distill_func_proto(&env->log, btf, t, >> + tname, &fmodel); >> + return ret; >> default: >> if (!prog_extension) >> return -EINVAL;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 4a6c47f3febe..f39b9fec37ab 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -215,6 +215,7 @@ enum bpf_attach_type { BPF_TRACE_FEXIT, BPF_MODIFY_RETURN, BPF_LSM_MAC, + BPF_TRACE_ITER, __MAX_BPF_ATTACH_TYPE }; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 91728e0f27eb..fd36c22685d9 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7074,6 +7074,11 @@ static int check_return_code(struct bpf_verifier_env *env) return 0; range = tnum_const(0); break; + case BPF_PROG_TYPE_TRACING: + if (env->prog->expected_attach_type != BPF_TRACE_ITER) + return 0; + range = tnum_const(0); + break; default: return 0; } @@ -10454,6 +10459,7 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) struct bpf_prog *tgt_prog = prog->aux->linked_prog; u32 btf_id = prog->aux->attach_btf_id; const char prefix[] = "btf_trace_"; + struct btf_func_model fmodel; int ret = 0, subprog = -1, i; struct bpf_trampoline *tr; const struct btf_type *t; @@ -10595,6 +10601,20 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) prog->aux->attach_func_proto = t; prog->aux->attach_btf_trace = true; return 0; + case BPF_TRACE_ITER: + if (!btf_type_is_func(t)) { + verbose(env, "attach_btf_id %u is not a function\n", + btf_id); + return -EINVAL; + } + t = btf_type_by_id(btf, t->type); + if (!btf_type_is_func_proto(t)) + return -EINVAL; + prog->aux->attach_func_name = tname; + prog->aux->attach_func_proto = t; + ret = btf_distill_func_proto(&env->log, btf, t, + tname, &fmodel); + return ret; default: if (!prog_extension) return -EINVAL; diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 4a6c47f3febe..f39b9fec37ab 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -215,6 +215,7 @@ enum bpf_attach_type { BPF_TRACE_FEXIT, BPF_MODIFY_RETURN, BPF_LSM_MAC, + BPF_TRACE_ITER, __MAX_BPF_ATTACH_TYPE };
A bpf_iter program is a tracing program with attach type BPF_TRACE_ITER. The load attribute attach_btf_id is used by the verifier against a particular kernel function, e.g., __bpf_iter__bpf_map in our previous bpf_map iterator. The program return value must be 0 for now. In the future, other return values may be used for filtering or teminating the iterator. Signed-off-by: Yonghong Song <yhs@fb.com> --- include/uapi/linux/bpf.h | 1 + kernel/bpf/verifier.c | 20 ++++++++++++++++++++ tools/include/uapi/linux/bpf.h | 1 + 3 files changed, 22 insertions(+)