A kfunc may already return an arena pointer on its own, which the program casts back into the arena address space to use. Let the members of a by-value struct it returns be arena pointers as well, rather than scalars only. Signed-off-by: Yonghong Song --- kernel/bpf/verifier.c | 23 ++++++++++--------- .../selftests/bpf/progs/aggregate_ret_kfunc.c | 2 +- 2 files changed, 13 insertions(+), 12 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index edbc48a1fdc8..0c2181d58748 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -14090,12 +14090,12 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, const char *member_note = ""; /* - * The returned struct comes back as raw register bits modeled - * as an unknown scalar, so it must contain only scalars: - * otherwise a pointer field would be laundered into a scalar - * and escape provenance and reference tracking. + * The returned struct may only contain scalars and arena pointers + * as its members. Otherwise, any other pointer would be laundered + * into a scalar and escape provenance and reference tracking. */ - if (!btf_struct_member_walk(env, desc_btf, t, BTF_MEMBER_SCALAR, 0, &path)) { + if (!btf_struct_member_walk(env, desc_btf, t, + BTF_MEMBER_SCALAR | BTF_MEMBER_ARENA_PTR, 0, &path)) { if (path.too_deep) { member_note = bpf_diag_fmt( env, " It nests structs more than %d levels deep.", @@ -14106,7 +14106,7 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, const struct btf_type *bad_type; verbose(env, - "kernel function %s returns %s %s that is not composed of scalars\n", + "kernel function %s returns %s %s that is not composed of scalars or arena pointers\n", func_name, btf_type_str(t), btf_name_by_offset(desc_btf, t->name_off)); btf_member_path_str(desc_btf, &path, bad_name, sizeof(bad_name)); @@ -14114,15 +14114,16 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, verbose(env, "member '%s' has type %s\n", bad_name, btf_type_str(bad_type)); member_note = bpf_diag_fmt( - env, " Its member '%s' is %s, not a scalar.", bad_name, - btf_type_str(bad_type)); + env, + " Its member '%s' is %s, not a scalar or an arena pointer.", + bad_name, btf_type_str(bad_type)); } bpf_diag_program_structure( env, insn_idx, "unsupported kernel function return type", - "Call a kernel function that returns only scalars by value.", + "Call a kernel function that returns only scalars or arena pointers by value.", "%s() returns %s %s by value.%s " - "Only kfuncs returning scalar values, or " - "structures composed of scalar values are " + "Only kfuncs returning scalar values or arena pointers, or " + "structures composed of scalar values and arena pointers are " "supported.", func_name, btf_type_str(t), btf_name_by_offset(desc_btf, t->name_off), member_note); diff --git a/tools/testing/selftests/bpf/progs/aggregate_ret_kfunc.c b/tools/testing/selftests/bpf/progs/aggregate_ret_kfunc.c index d6b422ae9784..f10e5cf6fd89 100644 --- a/tools/testing/selftests/bpf/progs/aggregate_ret_kfunc.c +++ b/tools/testing/selftests/bpf/progs/aggregate_ret_kfunc.c @@ -71,7 +71,7 @@ __naked int aggregate_ret_kfunc_fastcall_fail(void) SEC("tc") __arch_x86_64 __arch_arm64 -__failure __msg("is not composed of scalars") +__failure __msg("is not composed of scalars or arena pointers") __naked int aggregate_ret_kfunc_ptr_fail(void) { asm volatile ( -- 2.53.0-Meta