From patchwork Mon Aug 9 06:03:15 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yonghong Song X-Patchwork-Id: 12425453 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE183C4338F for ; Mon, 9 Aug 2021 06:03:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8CACF61051 for ; Mon, 9 Aug 2021 06:03:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233185AbhHIGDj (ORCPT ); Mon, 9 Aug 2021 02:03:39 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:61454 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233181AbhHIGDj (ORCPT ); Mon, 9 Aug 2021 02:03:39 -0400 Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 1795xxhL022731 for ; Sun, 8 Aug 2021 23:03:19 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : content-type : content-transfer-encoding : mime-version; s=facebook; bh=hNALOOnN2rHnn+zBk60FyiuRDqG2WyK40m9nIkenaXc=; b=qKYFdmGUHgxS/eVYsf/D5sy8nxU1M/nabiSGSkCkfkkRB04VdfZkkZIC0I9/GYPzIgnZ tw5gdAx61GCog8mBNKylz9i4eMGDTVYbS8M0AJz+RN9k9dkjwbhLkCxIh/19w5yD0YvB cC58fIn37hiTarfDzFsBZOgjU3atMa/dRgk= Received: from maileast.thefacebook.com ([163.114.130.16]) by mx0a-00082601.pphosted.com with ESMTP id 3a9ngpy3h4-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Sun, 08 Aug 2021 23:03:19 -0700 Received: from intmgw001.37.frc1.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::f) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Sun, 8 Aug 2021 23:03:17 -0700 Received: by devbig003.ftw2.facebook.com (Postfix, from userid 128203) id 4A1545CD4D1D; Sun, 8 Aug 2021 23:03:15 -0700 (PDT) From: Yonghong Song To: CC: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , , Subject: [PATCH bpf v2 1/2] bpf: don't call bpf_get_current_[ancestor_]cgroup_id() in sleepable progs Date: Sun, 8 Aug 2021 23:03:15 -0700 Message-ID: <20210809060315.1175802-1-yhs@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210809060310.1174777-1-yhs@fb.com> References: <20210809060310.1174777-1-yhs@fb.com> X-FB-Internal: Safe X-FB-Source: Intern X-Proofpoint-GUID: LYkN7rMjX2p8g1VCXO-y_mDrhQIgFvAx X-Proofpoint-ORIG-GUID: LYkN7rMjX2p8g1VCXO-y_mDrhQIgFvAx X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-09_01:2021-08-06,2021-08-09 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 spamscore=0 clxscore=1015 suspectscore=0 mlxlogscore=999 priorityscore=1501 malwarescore=0 impostorscore=0 adultscore=0 lowpriorityscore=0 mlxscore=0 phishscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108090048 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Currently, if bpf_get_current_cgroup_id() or bpf_get_current_ancestor_cgroup_id() helper is called with sleepable programs e.g., sleepable fentry/fmod_ret/fexit/lsm programs, a rcu warning may appear. For example, if I added the following hack to test_progs/test_lsm sleepable fentry program test_sys_setdomainname: --- a/tools/testing/selftests/bpf/progs/lsm.c +++ b/tools/testing/selftests/bpf/progs/lsm.c @@ -168,6 +168,10 @@ int BPF_PROG(test_sys_setdomainname, struct pt_regs *regs) int buf = 0; long ret; + __u64 cg_id = bpf_get_current_cgroup_id(); + if (cg_id == 1000) + copy_test++; + ret = bpf_copy_from_user(&buf, sizeof(buf), ptr); if (len == -2 && ret == 0 && buf == 1234) copy_test++; I will hit the following rcu warning: include/linux/cgroup.h:481 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by test_progs/260: #0: ffffffffa5173360 (rcu_read_lock_trace){....}-{0:0}, at: __bpf_prog_enter_sleepable+0x0/0xa0 stack backtrace: CPU: 1 PID: 260 Comm: test_progs Tainted: G O 5.14.0-rc2+ #176 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack_lvl+0x56/0x7b bpf_get_current_cgroup_id+0x9c/0xb1 bpf_prog_a29888d1c6706e09_test_sys_setdomainname+0x3e/0x89c bpf_trampoline_6442469132_0+0x2d/0x1000 __x64_sys_setdomainname+0x5/0x110 do_syscall_64+0x3a/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae I can get similar warning using bpf_get_current_ancestor_cgroup_id() helper. syzbot reported a similar issue in [1] for syscall program. Helper bpf_get_current_cgroup_id() or bpf_get_current_ancestor_cgroup_id() has the following callchain: task_dfl_cgroup task_css_set task_css_set_check and we have #define task_css_set_check(task, __c) \ rcu_dereference_check((task)->cgroups, \ lockdep_is_held(&cgroup_mutex) || \ lockdep_is_held(&css_set_lock) || \ ((task)->flags & PF_EXITING) || (__c)) Since cgroup_mutex/css_set_lock is not held and the task is not existing and rcu read_lock is not held, a warning will be issued. Note that bpf sleepable program is protected by rcu_read_lock_trace(). To fix the issue, let us make these two helpers not available to sleepable program. I marked the patch fixing 95b861a7935b ("bpf: Allow bpf_get_current_ancestor_cgroup_id for tracing") which added bpf_get_current_ancestor_cgroup_id() to 5.14. I think backporting 5.14 is probably good enough as sleepable progrems are not widely used. This patch should fix [1] as well since syscall program is a sleepable program and bpf_get_current_cgroup_id() is not available to syscall program any more. [1] https://lore.kernel.org/bpf/0000000000006d5cab05c7d9bb87@google.com/ Reported-by: syzbot+7ee5c2c09c284495371f@syzkaller.appspotmail.com Fixes: 95b861a7935b ("bpf: Allow bpf_get_current_ancestor_cgroup_id for tracing") Signed-off-by: Yonghong Song --- kernel/trace/bpf_trace.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index b4916ef388ad..eaa8a8ffbe46 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1016,9 +1016,11 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) #endif #ifdef CONFIG_CGROUPS case BPF_FUNC_get_current_cgroup_id: - return &bpf_get_current_cgroup_id_proto; + return prog->aux->sleepable ? + NULL : &bpf_get_current_cgroup_id_proto; case BPF_FUNC_get_current_ancestor_cgroup_id: - return &bpf_get_current_ancestor_cgroup_id_proto; + return prog->aux->sleepable ? + NULL : &bpf_get_current_ancestor_cgroup_id_proto; #endif case BPF_FUNC_send_signal: return &bpf_send_signal_proto; From patchwork Mon Aug 9 06:03:20 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yonghong Song X-Patchwork-Id: 12425455 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A4C39C4338F for ; Mon, 9 Aug 2021 06:03:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 874AA61051 for ; Mon, 9 Aug 2021 06:03:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233174AbhHIGDo (ORCPT ); Mon, 9 Aug 2021 02:03:44 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:24612 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S233045AbhHIGDn (ORCPT ); Mon, 9 Aug 2021 02:03:43 -0400 Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.16.0.43/8.16.0.43) with SMTP id 17960ikl012022 for ; Sun, 8 Aug 2021 23:03:23 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=8O7EPMKwcEVKq8CKQP/N2pk1SHhV6DidSADlVJXFVfY=; b=e0BArxBXNpatndZlmUEtAlW9Lc7BUZPMh4marOfecoTcIbVxE1UctG2M62kT/E0Z2Mkj adPdoOOFlWsmD0hHuWty3CpPtFkBnsvPnvY0e4mTFGmhhhBKt06fuMGCMs06Sm/D+hr6 Z2DGn/+IuCtWCDpG8pWa38h0QJk58tgrc68= Received: from maileast.thefacebook.com ([163.114.130.16]) by m0089730.ppops.net with ESMTP id 3a9npdf3ax-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Sun, 08 Aug 2021 23:03:23 -0700 Received: from intmgw001.37.frc1.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::e) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Sun, 8 Aug 2021 23:03:22 -0700 Received: by devbig003.ftw2.facebook.com (Postfix, from userid 128203) id 638125CD4D78; Sun, 8 Aug 2021 23:03:20 -0700 (PDT) From: Yonghong Song To: CC: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Subject: [PATCH bpf v2 2/2] bpf: add missing bpf_read_[un]lock_trace() for syscall program Date: Sun, 8 Aug 2021 23:03:20 -0700 Message-ID: <20210809060320.1176782-1-yhs@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210809060310.1174777-1-yhs@fb.com> References: <20210809060310.1174777-1-yhs@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-FB-Source: Intern X-Proofpoint-GUID: eMkWb8nECcthqd6ZG011a2Y9hQ_kCSlT X-Proofpoint-ORIG-GUID: eMkWb8nECcthqd6ZG011a2Y9hQ_kCSlT X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-09_01:2021-08-06,2021-08-09 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 lowpriorityscore=0 malwarescore=0 clxscore=1015 adultscore=0 impostorscore=0 mlxscore=0 suspectscore=0 spamscore=0 priorityscore=1501 phishscore=0 mlxlogscore=809 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108090048 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net Commit 79a7f8bdb159d ("bpf: Introduce bpf_sys_bpf() helper and program type.") added support for syscall program, which is a sleepable program. But the program run missed bpf_read_lock_trace()/bpf_read_unlock_trace(), which is needed to ensure proper rcu callback invocations. This patch added bpf_read_[un]lock_trace() properly. Fixes: 79a7f8bdb159d ("bpf: Introduce bpf_sys_bpf() helper and program type.") Signed-off-by: Yonghong Song Acked-by: Andrii Nakryiko --- net/bpf/test_run.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c index 1cc75c811e24..caa16bf30fb5 100644 --- a/net/bpf/test_run.c +++ b/net/bpf/test_run.c @@ -7,6 +7,7 @@ #include #include #include +#include #include #include #include @@ -951,7 +952,10 @@ int bpf_prog_test_run_syscall(struct bpf_prog *prog, goto out; } } + + rcu_read_lock_trace(); retval = bpf_prog_run_pin_on_cpu(prog, ctx); + rcu_read_unlock_trace(); if (copy_to_user(&uattr->test.retval, &retval, sizeof(u32))) { err = -EFAULT;