From 54c11ec4935a61af32bb03fc52e7172c97bd7203 Mon Sep 17 00:00:00 2001 From: Andrii Nakryiko Date: Thu, 4 Jan 2024 16:09:04 -0800 Subject: bpf: prepare btf_prepare_func_args() for multiple tags per argument Add btf_arg_tag flags enum to be able to record multiple tags per argument. Also streamline pointer argument processing some more. Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20240105000909.2818934-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov --- kernel/bpf/btf.c | 53 +++++++++++++++++++++++++++++++++++---------------- kernel/bpf/verifier.c | 1 - 2 files changed, 37 insertions(+), 17 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index dbe7a590f565..1636b574a63d 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6946,6 +6946,11 @@ static bool btf_is_dynptr_ptr(const struct btf *btf, const struct btf_type *t) return false; } +enum btf_arg_tag { + ARG_TAG_CTX = 0x1, + ARG_TAG_NONNULL = 0x2, +}; + /* Process BTF of a function to produce high-level expectation of function * arguments (like ARG_PTR_TO_CTX, or ARG_PTR_TO_MEM, etc). This information * is cached in subprog info for reuse. @@ -7027,10 +7032,8 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) * Only PTR_TO_CTX and SCALAR are supported atm. */ for (i = 0; i < nargs; i++) { - bool is_nonnull = false; const char *tag; - - t = btf_type_by_id(btf, args[i].type); + u32 tags = 0; tag = btf_find_decl_tag_value(btf, fn_t, i, "arg:"); if (IS_ERR(tag) && PTR_ERR(tag) == -ENOENT) { @@ -7048,43 +7051,61 @@ int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog) bpf_log(log, "arg#%d type tag is not supported in static functions\n", i); return -EOPNOTSUPP; } + if (strcmp(tag, "ctx") == 0) { - sub->args[i].arg_type = ARG_PTR_TO_CTX; - continue; + tags |= ARG_TAG_CTX; + } else if (strcmp(tag, "nonnull") == 0) { + tags |= ARG_TAG_NONNULL; + } else { + bpf_log(log, "arg#%d has unsupported set of tags\n", i); + return -EOPNOTSUPP; } - if (strcmp(tag, "nonnull") == 0) - is_nonnull = true; } + t = btf_type_by_id(btf, args[i].type); while (btf_type_is_modifier(t)) t = btf_type_by_id(btf, t->type); - if (btf_type_is_ptr(t) && btf_get_prog_ctx_type(log, btf, t, prog_type, i)) { + if (!btf_type_is_ptr(t)) + goto skip_pointer; + + if ((tags & ARG_TAG_CTX) || btf_get_prog_ctx_type(log, btf, t, prog_type, i)) { + if (tags & ~ARG_TAG_CTX) { + bpf_log(log, "arg#%d has invalid combination of tags\n", i); + return -EINVAL; + } sub->args[i].arg_type = ARG_PTR_TO_CTX; continue; } - if (btf_type_is_ptr(t) && btf_is_dynptr_ptr(btf, t)) { + if (btf_is_dynptr_ptr(btf, t)) { + if (tags) { + bpf_log(log, "arg#%d has invalid combination of tags\n", i); + return -EINVAL; + } sub->args[i].arg_type = ARG_PTR_TO_DYNPTR | MEM_RDONLY; continue; } - if (is_global && btf_type_is_ptr(t)) { + if (is_global) { /* generic user data pointer */ u32 mem_size; t = btf_type_skip_modifiers(btf, t->type, NULL); ref_t = btf_resolve_size(btf, t, &mem_size); if (IS_ERR(ref_t)) { - bpf_log(log, - "arg#%d reference type('%s %s') size cannot be determined: %ld\n", - i, btf_type_str(t), btf_name_by_offset(btf, t->name_off), + bpf_log(log, "arg#%d reference type('%s %s') size cannot be determined: %ld\n", + i, btf_type_str(t), btf_name_by_offset(btf, t->name_off), PTR_ERR(ref_t)); return -EINVAL; } - sub->args[i].arg_type = is_nonnull ? ARG_PTR_TO_MEM : ARG_PTR_TO_MEM_OR_NULL; + sub->args[i].arg_type = ARG_PTR_TO_MEM | PTR_MAYBE_NULL; + if (tags & ARG_TAG_NONNULL) + sub->args[i].arg_type &= ~PTR_MAYBE_NULL; sub->args[i].mem_size = mem_size; continue; } - if (is_nonnull) { - bpf_log(log, "arg#%d marked as non-null, but is not a pointer type\n", i); + +skip_pointer: + if (tags) { + bpf_log(log, "arg#%d has pointer tag, but is not a pointer type\n", i); return -EINVAL; } if (btf_type_is_int(t) || btf_is_any_enum(t)) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 5b33d65eef7b..27ad463b3bdd 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -20058,7 +20058,6 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog) state->first_insn_idx = env->subprog_info[subprog].start; state->last_insn_idx = -1; - regs = state->frame[state->curframe]->regs; if (subprog || env->prog->type == BPF_PROG_TYPE_EXT) { const char *sub_name = subprog_name(env, subprog); -- cgit