From patchwork Wed Sep 11 03:37:15 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Philo Lu X-Patchwork-Id: 13799641 Received: from out30-119.freemail.mail.aliyun.com (out30-119.freemail.mail.aliyun.com [115.124.30.119]) (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 9FFFD37708; Wed, 11 Sep 2024 03:37:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.119 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726025849; cv=none; b=ESElGoC2ieuTsZdiIkWKEP++urwkyqUrKWQ3OfnwioUu4eY6CbhcvL4hCxo8nWTkI25IE7AzvOKjIHs/jT4RXkNnqvte4sLTkjcYNtm/nFQR+qKYo6XQ6sYm7tbB95MDMrYVUNVc+p0KblvS04TKB1XH6IQYQ8w+By2PXx3kpSg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726025849; c=relaxed/simple; bh=yjzfZ0RmwQaNWmpgdz4REgB2axh5G/3VoM2mR8RwPpg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=d/0SylqVUXwGTVWqfr8RB5kHRHNYM6/HNZdXbs0I49YPcz9ZTTCrpANbnqckYndhjGuXXSSYjyvk9T3xOEWOiCKmIiPCFQ6qUlz7ocTGrEA4DHw96JqGOOF4fU3Ckb8qkMRLEDdIwlxSnpX3KnOOJnh6cAjBF93VC4GJpJglhWs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=ydhKiXGd; arc=none smtp.client-ip=115.124.30.119 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="ydhKiXGd" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1726025844; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=WwcZsrFs/zwinoTKm43cGq8al6XWxgQc/c+7MSHqMic=; b=ydhKiXGdEFhHlWs0dk07tNL4kRkXwdi+K3Os6tLpeFXf5M5FP1FJoSCUGhJg9Ciu2zX1lMpjKcSybglBbRlpUx+f0bEiZwnjWec83kh2tgQ/iEw16xtuONVunGwhjhC68jCiXyPOoE/rZ2gYFZuM/yJS2UAwtjFFUzO7UEUuYhA= Received: from localhost(mailfrom:lulie@linux.alibaba.com fp:SMTPD_---0WEmEW00_1726025841) by smtp.aliyun-inc.com; Wed, 11 Sep 2024 11:37:22 +0800 From: Philo Lu To: bpf@vger.kernel.org Cc: edumazet@google.com, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, martin.lau@linux.dev, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com, mykolal@fb.com, shuah@kernel.org, mcoquelin.stm32@gmail.com, alexandre.torgue@foss.st.com, thinker.li@gmail.com, juntong.deng@outlook.com, jrife@google.com, alan.maguire@oracle.com, davemarchevsky@fb.com, dxu@dxuuu.xyz, vmalik@redhat.com, cupertino.miranda@oracle.com, mattbobrowski@google.com, xuanzhuo@linux.alibaba.com, netdev@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH bpf-next v3 1/5] bpf: Support __nullable argument suffix for tp_btf Date: Wed, 11 Sep 2024 11:37:15 +0800 Message-Id: <20240911033719.91468-2-lulie@linux.alibaba.com> X-Mailer: git-send-email 2.32.0.3.g01195cf9f In-Reply-To: <20240911033719.91468-1-lulie@linux.alibaba.com> References: <20240911033719.91468-1-lulie@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Pointers passed to tp_btf were trusted to be valid, but some tracepoints do take NULL pointer as input, such as trace_tcp_send_reset(). Then the invalid memory access cannot be detected by verifier. This patch fix it by add a suffix "__nullable" to the unreliable argument. The suffix is shown in btf, and PTR_MAYBE_NULL will be added to nullable arguments. Then users must check the pointer before use it. A problem here is that we use "btf_trace_##call" to search func_proto. As it is a typedef, argument names as well as the suffix are not recorded. To solve this, I use bpf_raw_event_map to find "__bpf_trace##template" from "btf_trace_##call", and then we can see the suffix. Suggested-by: Alexei Starovoitov Signed-off-by: Philo Lu --- kernel/bpf/btf.c | 9 +++++++++ kernel/bpf/verifier.c | 36 ++++++++++++++++++++++++++++++++---- 2 files changed, 41 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 1e29281653c62..d1ea38d08f301 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6385,6 +6385,12 @@ static bool prog_args_trusted(const struct bpf_prog *prog) } } +static bool prog_arg_maybe_null(const struct bpf_prog *prog, const struct btf *btf, + const struct btf_param *arg) +{ + return btf_param_match_suffix(btf, arg, "__nullable"); +} + int btf_ctx_arg_offset(const struct btf *btf, const struct btf_type *func_proto, u32 arg_no) { @@ -6554,6 +6560,9 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, if (prog_args_trusted(prog)) info->reg_type |= PTR_TRUSTED; + if (prog_arg_maybe_null(prog, btf, &args[arg])) + info->reg_type |= PTR_MAYBE_NULL; + if (tgt_prog) { enum bpf_prog_type tgt_type; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 217eb0eafa2a6..72c232fc451be 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -28,6 +28,8 @@ #include #include #include +#include +#include #include "disasm.h" @@ -21788,11 +21790,13 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, { bool prog_extension = prog->type == BPF_PROG_TYPE_EXT; bool prog_tracing = prog->type == BPF_PROG_TYPE_TRACING; + char trace_symbol[KSYM_SYMBOL_LEN]; const char prefix[] = "btf_trace_"; + struct bpf_raw_event_map *btp; int ret = 0, subprog = -1, i; const struct btf_type *t; bool conservative = true; - const char *tname; + const char *tname, *fname; struct btf *btf; long addr = 0; struct module *mod = NULL; @@ -21923,10 +21927,34 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, return -EINVAL; } tname += sizeof(prefix) - 1; - t = btf_type_by_id(btf, t->type); - if (!btf_type_is_ptr(t)) - /* should never happen in valid vmlinux build */ + + /* The func_proto of "btf_trace_##tname" is generated from typedef without argument + * names. Thus using bpf_raw_event_map to get argument names. + */ + btp = bpf_get_raw_tracepoint(tname); + if (!btp) return -EINVAL; + fname = kallsyms_lookup((unsigned long)btp->bpf_func, NULL, NULL, NULL, + trace_symbol); + bpf_put_raw_tracepoint(btp); + + if (fname) + ret = btf_find_by_name_kind(btf, fname, BTF_KIND_FUNC); + + if (!fname || ret < 0) { + bpf_log(log, "Cannot find btf of tracepoint template, fall back to %s%s.\n", + prefix, tname); + t = btf_type_by_id(btf, t->type); + if (!btf_type_is_ptr(t)) + /* should never happen in valid vmlinux build */ + return -EINVAL; + } else { + t = btf_type_by_id(btf, ret); + if (!btf_type_is_func(t)) + /* should never happen in valid vmlinux build */ + return -EINVAL; + } + t = btf_type_by_id(btf, t->type); if (!btf_type_is_func_proto(t)) /* should never happen in valid vmlinux build */