From patchwork Thu Sep 5 07:56:18 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Philo Lu X-Patchwork-Id: 13791902 Received: from out30-132.freemail.mail.aliyun.com (out30-132.freemail.mail.aliyun.com [115.124.30.132]) (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 5CD1319340D; Thu, 5 Sep 2024 07:56:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.132 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725522997; cv=none; b=UnY+kKHIqDOcoJcD0ggeWGJozfzEgCxGl2CFz1BfsS/YBbyHCljmuxmXVdRLKFQWa74qyi8aTYUAuBP5+8K2DdH0/9XMPBIOMUAHP29C3kpOiC/WVbj6PrWrw0fLoVLbiRj/oiUKiRfvae1Jm8dA5N4B5lH3MHIZ2WbtvXa23Dw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725522997; c=relaxed/simple; bh=67C+ySKUMFOl/Vw/EWHL5BU7fz6lIct5OzmIokYnQIQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Yk3T06kUhWX9e0aLjWc7YM0RZqkzu1ZLQA//De9Ba7IPXBCVFlEc57QLIN7YJuI/J6FuigDM1x7R1xpfZoNRepgIJcSPIEFWYiayV3VbDnCvbgbDQamnlerSMCuvKjbsU9HvJSVTeWT0TF4X7oCyfj66It6bPsuFbR9jAnfSyRA= 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=doEQQoTG; arc=none smtp.client-ip=115.124.30.132 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="doEQQoTG" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1725522986; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=XIpXmKG/dvqtkO380OYf1vfqjzkl8IpnbYNB+J/73MQ=; b=doEQQoTG/kdjL2Y7oLNSv/Y5ZA0ZtaZJs/d8Kl+YgCImoiCicQ+F1ePQi8tZ9J9Y4dSwb+EEY9iZtUu0rZymLtLvf/4pIsZHaGJTuh3vPHEFknPKVQlo4J2BdXQ2mHRBuF7gFsTJ+uC0KJmQhAwSkOzXUjizYAAQAYeeyTwYxss= Received: from localhost(mailfrom:lulie@linux.alibaba.com fp:SMTPD_---0WEKrrCP_1725522983) by smtp.aliyun-inc.com; Thu, 05 Sep 2024 15:56:24 +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 v2 1/5] bpf: Support __nullable argument suffix for tp_btf Date: Thu, 5 Sep 2024 15:56:18 +0800 Message-Id: <20240905075622.66819-2-lulie@linux.alibaba.com> X-Mailer: git-send-email 2.32.0.3.g01195cf9f In-Reply-To: <20240905075622.66819-1-lulie@linux.alibaba.com> References: <20240905075622.66819-1-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 | 13 +++++++++++++ kernel/bpf/verifier.c | 36 +++++++++++++++++++++++++++++++++--- 2 files changed, 46 insertions(+), 3 deletions(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 1e29281653c62..157f5e1247c81 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -6385,6 +6385,16 @@ 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) +{ + if (prog->type != BPF_PROG_TYPE_TRACING || + prog->expected_attach_type != BPF_TRACE_RAW_TP) + return false; + + 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 +6564,9 @@ 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..9ee68ed915dfe 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -28,6 +28,7 @@ #include #include #include +#include #include "disasm.h" @@ -21780,6 +21781,8 @@ static int check_non_sleepable_error_inject(u32 btf_id) return btf_id_set_contains(&btf_non_sleepable_error_inject, btf_id); } +#define BTF_MAX_NAME_SIZE 128 + int bpf_check_attach_target(struct bpf_verifier_log *log, const struct bpf_prog *prog, const struct bpf_prog *tgt_prog, @@ -21788,6 +21791,8 @@ 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[BTF_MAX_NAME_SIZE]; + const struct bpf_raw_event_map *btp; const char prefix[] = "btf_trace_"; int ret = 0, subprog = -1, i; const struct btf_type *t; @@ -21795,6 +21800,7 @@ int bpf_check_attach_target(struct bpf_verifier_log *log, const char *tname; struct btf *btf; long addr = 0; + char *fname; struct module *mod = NULL; if (!btf_id) { @@ -21923,10 +21929,34 @@ 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. For module, the module + * name is printed in "%ps" after the template function name, so use strsep to cut + * it off. + */ + btp = bpf_get_raw_tracepoint(tname); + if (!btp) return -EINVAL; + sprintf(trace_symbol, "%ps", btp->bpf_func); + fname = trace_symbol; + fname = strsep(&fname, " "); + + ret = btf_find_by_name_kind(btf, fname, BTF_KIND_FUNC); + if (ret < 0) { + bpf_log(log, "Cannot find btf of template %s, fall back to %s%s.\n", + fname, 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 */