From patchwork Thu Aug 8 23:22:29 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 13758248 X-Patchwork-Delegate: bpf@iogearbox.net Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A59321474A5 for ; Thu, 8 Aug 2024 23:22:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723159363; cv=none; b=LESXEXoloZAnGS/LoE+jGa9sXBbCXbNCQ+pYYK61yoRlYccme/EXpMKgMkvWzHBuM0+52XqazffRV7uZ8ucsC5/JRnZ9jFSLCuadCMACMHFiqr9PpZAPc244y450dQUgtKLOm7p4I/c9le+2U6hswyFWcHL2LhiF97RwYu+03/4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723159363; c=relaxed/simple; bh=I0yNWr6fIJl96Sh2OqzuVYEikJ8GnLgK2heAeag7+hM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GvXvwwTxT3AdUXjAmGsLpr4MWAkoNQ6QKFpK/ANMn6L+mpoboV9K86yGgC3ryt9riAZgdm0RkTGhSDQqJOBLxAs/dr9UPfiMk81D80mRNNbSGXplQlTytjeegcD6Acf4jRDeHwvmMeXxlYRxTbjwFK/4MvLBFx65sAPUNbTBnsc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=ZswSJP03; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZswSJP03" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0A1D1C32782; Thu, 8 Aug 2024 23:22:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1723159363; bh=I0yNWr6fIJl96Sh2OqzuVYEikJ8GnLgK2heAeag7+hM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZswSJP03N5+c9llw8FA2vn+ZE0kb1WLRMh2fByHuBpATujfcS17b875t5AUmaESo+ /TTc2SuZWQvSYnp/1FCpfnK4mYHI6D+e87qv/c4TVQh0cn8GKs+jSF4ZDbmlZP8ux5 ZjOwiEBFcz0mvukhImmSbIK7lFYQfjqzQNiobYp88HkO473JlQMPh8MjAdpLQxUAPq 3BrZXGJ4x8ItxSyBK2eM3xFMus1WLdEMM021qPFtNGH8k9qoFNcq8WTYr7lCipfySk 0lhUmlG5V0MzfWjumU1CZNmlqJMeMt7PUM/YyrHUNUUF2U/izIqZ3Ouk/QDAF3IoQa j3JzOy44getKg== From: Andrii Nakryiko To: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, martin.lau@kernel.org Cc: tj@kernel.org, void@manifault.com, Andrii Nakryiko Subject: [PATCH bpf-next 2/3] bpf: allow passing struct bpf_iter_ as kfunc arguments Date: Thu, 8 Aug 2024 16:22:29 -0700 Message-ID: <20240808232230.2848712-3-andrii@kernel.org> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20240808232230.2848712-1-andrii@kernel.org> References: <20240808232230.2848712-1-andrii@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net There are potentially useful cases where a specific iterator type might need to be passed into some kfunc. So, in addition to existing bpf_iter__{new,next,destroy}() kfuncs, allow to pass iterator pointer to any kfunc. We employ "__iter" naming suffix for arguments that are meant to accept iterators. We also enforce that they accept PTR -> STRUCT btf_iter_ type chain and point to a valid initialized on-the-stack iterator state. Signed-off-by: Andrii Nakryiko --- kernel/bpf/verifier.c | 35 ++++++++++++++++++++++++----------- 1 file changed, 24 insertions(+), 11 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index df3be12096cf..920d7c5fe944 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7970,12 +7970,17 @@ static bool is_iter_destroy_kfunc(struct bpf_kfunc_call_arg_meta *meta) return meta->kfunc_flags & KF_ITER_DESTROY; } -static bool is_kfunc_arg_iter(struct bpf_kfunc_call_arg_meta *meta, int arg) +static bool is_kfunc_arg_iter(struct bpf_kfunc_call_arg_meta *meta, int arg_idx, + const struct btf_param *arg) { /* btf_check_iter_kfuncs() guarantees that first argument of any iter * kfunc is iter state pointer */ - return arg == 0 && is_iter_kfunc(meta); + if (is_iter_kfunc(meta)) + return arg_idx == 0; + + /* iter passed as an argument to a generic kfunc */ + return btf_param_match_suffix(meta->btf, arg, "__iter"); } static int process_iter_arg(struct bpf_verifier_env *env, int regno, int insn_idx, @@ -7983,14 +7988,20 @@ static int process_iter_arg(struct bpf_verifier_env *env, int regno, int insn_id { struct bpf_reg_state *regs = cur_regs(env), *reg = ®s[regno]; const struct btf_type *t; - const struct btf_param *arg; - int spi, err, i, nr_slots; - u32 btf_id; + int spi, err, i, nr_slots, btf_id; - /* btf_check_iter_kfuncs() ensures we don't need to validate anything here */ - arg = &btf_params(meta->func_proto)[0]; - t = btf_type_skip_modifiers(meta->btf, arg->type, NULL); /* PTR */ - t = btf_type_skip_modifiers(meta->btf, t->type, &btf_id); /* STRUCT */ + /* For iter_{new,next,destroy} functions, btf_check_iter_kfuncs() + * ensures struct convention, so we wouldn't need to do any BTF + * validation here. But given iter state can be passed as a parameter + * to any kfunc, if arg has "__iter" suffix, we need to be a bit more + * conservative here. + */ + btf_id = btf_check_iter_arg(meta->btf, meta->func_proto, regno - 1); + if (btf_id < 0) { + verbose(env, "expected valid iter pointer as arg #%d\n", regno); + return -EINVAL; + } + t = btf_type_by_id(meta->btf, btf_id); nr_slots = t->size / BPF_REG_SIZE; if (is_iter_new_kfunc(meta)) { @@ -8012,7 +8023,9 @@ static int process_iter_arg(struct bpf_verifier_env *env, int regno, int insn_id if (err) return err; } else { - /* iter_next() or iter_destroy() expect initialized iter state*/ + /* iter_next() or iter_destroy(), as well as any kfunc + * accepting iter argument, expect initialized iter state + */ err = is_iter_reg_valid_init(env, reg, meta->btf, btf_id, nr_slots); switch (err) { case 0: @@ -11382,7 +11395,7 @@ get_kfunc_ptr_arg_type(struct bpf_verifier_env *env, if (is_kfunc_arg_dynptr(meta->btf, &args[argno])) return KF_ARG_PTR_TO_DYNPTR; - if (is_kfunc_arg_iter(meta, argno)) + if (is_kfunc_arg_iter(meta, argno, &args[argno])) return KF_ARG_PTR_TO_ITER; if (is_kfunc_arg_list_head(meta->btf, &args[argno]))