This allows kfunc to request the prog_aux environment in their implementation, to have access to the originated bpf_prog for example.
Signed-off-by: Benjamin Tissoires bentiss@kernel.org
---
This is an RFC, and is not meant to be fully reviewed/applied as it is. I'm posting this to show what I wanted to explain in https://lore.kernel.org/bpf/mhkzkf4e23uvljtmwizwcxyuyat2tmfxn33xb4t7waafgmsa... --- kernel/bpf/verifier.c | 40 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 39 insertions(+), 1 deletion(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6fba9e2caa83..33b108db0025 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10909,6 +10909,11 @@ static bool is_kfunc_arg_sleepable_async_cb(const struct btf *btf, const struct return btf_param_match_suffix(btf, arg, "__s_async"); }
+static bool is_kfunc_arg_prog_aux(const struct btf *btf, const struct btf_param *arg) +{ + return btf_param_match_suffix(btf, arg, "__aux"); +} + static bool is_kfunc_arg_scalar_with_name(const struct btf *btf, const struct btf_param *arg, const char *name) @@ -11807,7 +11812,8 @@ static int check_kfunc_args(struct bpf_verifier_env *env, struct bpf_kfunc_call_
t = btf_type_skip_modifiers(btf, args[i].type, NULL);
- if (is_kfunc_arg_ignore(btf, &args[i])) + if (is_kfunc_arg_ignore(btf, &args[i]) || + is_kfunc_arg_prog_aux(btf, &args[i])) continue;
if (btf_type_is_scalar(t)) { @@ -19950,6 +19956,38 @@ static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, insn_buf[1] = ld_addrs[1]; insn_buf[2] = *insn; *cnt = 3; + } else { + struct bpf_kfunc_call_arg_meta meta; + struct bpf_insn kfunc_insn = *insn; + const struct btf_param *args; + u32 i, nargs, prog_aux_arg; + const char *func_name; + int ret; + + /* imm might not have func_id, so create a fake insn with the expected args */ + kfunc_insn.imm = desc->func_id; + + ret = fetch_kfunc_meta(env, &kfunc_insn, &meta, &func_name); + if (ret == 0) { + args = (const struct btf_param *)(meta.func_proto + 1); + nargs = btf_type_vlen(meta.func_proto); + prog_aux_arg = nargs; + + for (i = 0; i < nargs; i++) { + if (is_kfunc_arg_prog_aux(meta.btf, &args[i])) + prog_aux_arg = i; + } + + if (prog_aux_arg < nargs) { + struct bpf_insn ld_addrs[2] = { BPF_LD_IMM64(BPF_REG_1 + prog_aux_arg, + (long)env->prog->aux) }; + + insn_buf[0] = ld_addrs[0]; + insn_buf[1] = ld_addrs[1]; + insn_buf[2] = *insn; + *cnt = 3; + } + } } return 0; }