diff options
| author | KP Singh <kpsingh@google.com> | 2020-11-06 10:37:43 +0000 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-11-06 08:08:37 -0800 |
| commit | 3ca1032ab7ab010eccb107aa515598788f7d93bb (patch) | |
| tree | e09a5bff5dfa40b270ce5fe937ec1e0a9af7ff45 /kernel | |
| parent | 864ab0616dccf14e51618a24acc7cf23ddd2b98a (diff) | |
bpf: Implement get_current_task_btf and RET_PTR_TO_BTF_ID
The currently available bpf_get_current_task returns an unsigned integer
which can be used along with BPF_CORE_READ to read data from
the task_struct but still cannot be used as an input argument to a
helper that accepts an ARG_PTR_TO_BTF_ID of type task_struct.
In order to implement this helper a new return type, RET_PTR_TO_BTF_ID,
is added. This is similar to RET_PTR_TO_BTF_ID_OR_NULL but does not
require checking the nullness of returned pointer.
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20201106103747.2780972-6-kpsingh@chromium.org
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 7 | ||||
| -rw-r--r-- | kernel/trace/bpf_trace.c | 16 |
2 files changed, 21 insertions, 2 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 00960f6a83ec..10da26e55130 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5186,11 +5186,14 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn PTR_TO_BTF_ID : PTR_TO_BTF_ID_OR_NULL; regs[BPF_REG_0].btf_id = meta.ret_btf_id; } - } else if (fn->ret_type == RET_PTR_TO_BTF_ID_OR_NULL) { + } else if (fn->ret_type == RET_PTR_TO_BTF_ID_OR_NULL || + fn->ret_type == RET_PTR_TO_BTF_ID) { int ret_btf_id; mark_reg_known_zero(env, regs, BPF_REG_0); - regs[BPF_REG_0].type = PTR_TO_BTF_ID_OR_NULL; + regs[BPF_REG_0].type = fn->ret_type == RET_PTR_TO_BTF_ID ? + PTR_TO_BTF_ID : + PTR_TO_BTF_ID_OR_NULL; ret_btf_id = *fn->ret_btf_id; if (ret_btf_id == 0) { verbose(env, "invalid return type %d of func %s#%d\n", diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 4517c8b66518..e4515b0f62a8 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1022,6 +1022,20 @@ const struct bpf_func_proto bpf_get_current_task_proto = { .ret_type = RET_INTEGER, }; +BPF_CALL_0(bpf_get_current_task_btf) +{ + return (unsigned long) current; +} + +BTF_ID_LIST_SINGLE(bpf_get_current_btf_ids, struct, task_struct) + +static const struct bpf_func_proto bpf_get_current_task_btf_proto = { + .func = bpf_get_current_task_btf, + .gpl_only = true, + .ret_type = RET_PTR_TO_BTF_ID, + .ret_btf_id = &bpf_get_current_btf_ids[0], +}; + BPF_CALL_2(bpf_current_task_under_cgroup, struct bpf_map *, map, u32, idx) { struct bpf_array *array = container_of(map, struct bpf_array, map); @@ -1265,6 +1279,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return &bpf_get_current_pid_tgid_proto; case BPF_FUNC_get_current_task: return &bpf_get_current_task_proto; + case BPF_FUNC_get_current_task_btf: + return &bpf_get_current_task_btf_proto; case BPF_FUNC_get_current_uid_gid: return &bpf_get_current_uid_gid_proto; case BPF_FUNC_get_current_comm: |