From patchwork Tue Apr 11 04:16:31 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Vernet X-Patchwork-Id: 13207022 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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 327B3C7619A for ; Tue, 11 Apr 2023 04:16:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229694AbjDKEQk (ORCPT ); Tue, 11 Apr 2023 00:16:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35872 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229640AbjDKEQj (ORCPT ); Tue, 11 Apr 2023 00:16:39 -0400 Received: from mail-qv1-f51.google.com (mail-qv1-f51.google.com [209.85.219.51]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B2A8FE74; Mon, 10 Apr 2023 21:16:37 -0700 (PDT) Received: by mail-qv1-f51.google.com with SMTP id om8so5591789qvb.3; Mon, 10 Apr 2023 21:16:37 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1681186596; x=1683778596; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=+/NRCUh21EwSCHQTGMkg0JbDBsWfdCVqSK+6Bs3uOLY=; b=C27iSmbNBoZDtfI5DW380E6Veo8NgFB+WxJ9hGYdraHeApKdy6KImA3DHTmdlDFqq3 b4mHr4Okki5JqMoN5tqok4zD0asyKlg4vwH2XHN+nS+UNoQAAzEfZIxSn64Pqqw2gqNQ Rn3hIrnlXjIGFSHh8hZjtd83qJaz9kX4oZP7igLx3VHqvLI4FPeRNrxL+itJYYpwUMm+ mC5R99VhvWg/y2ByE/YIYU65Rdw9jTP7PsMaFxFh0EpjxoOhhAtptz4A3z+iu0E9DV7q zY1Z5hdFMJq74LxQ/zJEd2F8gIZUInlD17Q4/zdUTN/EKOIpQizDeuUaGSngy83PCMdh teNw== X-Gm-Message-State: AAQBX9fDyt27sT5ZcOJN027qK+aDJUxvunvvWGFfrY9M5/cwF6uRGhEz o6AmAHWHmKByU7lp+I0MRgtz/dD9CMUIroAF X-Google-Smtp-Source: AKy350ZNmWN4ftdjoIgUAj4L2KpIVN9ISqiVmUxWvAzY5eYXZk6RL7RPUGR6JJaauuaq2XBa3OtTqQ== X-Received: by 2002:a05:6214:ac6:b0:577:5ffe:e0ce with SMTP id g6-20020a0562140ac600b005775ffee0cemr26837599qvi.25.1681186596414; Mon, 10 Apr 2023 21:16:36 -0700 (PDT) Received: from localhost ([2620:10d:c091:400::5:8681]) by smtp.gmail.com with ESMTPSA id u6-20020a0cfe46000000b005e2007584f1sm3855319qvs.24.2023.04.10.21.16.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 10 Apr 2023 21:16:35 -0700 (PDT) From: David Vernet To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, linux-kernel@vger.kernel.org, kernel-team@meta.com Subject: [PATCH bpf-next 1/3] bpf: Make bpf_cgroup_acquire() KF_RCU | KF_RET_NULL Date: Mon, 10 Apr 2023 23:16:31 -0500 Message-Id: <20230411041633.179404-1-void@manifault.com> X-Mailer: git-send-email 2.40.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net struct cgroup is already an RCU-safe type in the verifier. We can therefore update bpf_cgroup_acquire() to be KF_RCU | KF_RET_NULL, and subsequently remove bpf_cgroup_kptr_get(). This patch does the first of these by updating bpf_cgroup_acquire() to be KF_RCU | KF_RET_NULL, and also updates selftests accordingly. Signed-off-by: David Vernet --- kernel/bpf/helpers.c | 5 ++- .../selftests/bpf/progs/cgrp_kfunc_common.h | 5 +++ .../selftests/bpf/progs/cgrp_kfunc_failure.c | 35 +++++++++++++++---- .../selftests/bpf/progs/cgrp_kfunc_success.c | 5 ++- 4 files changed, 40 insertions(+), 10 deletions(-) diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index b6a5cda5bb59..71f0604bdc97 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -2037,8 +2037,7 @@ __bpf_kfunc void bpf_task_release(struct task_struct *p) */ __bpf_kfunc struct cgroup *bpf_cgroup_acquire(struct cgroup *cgrp) { - cgroup_get(cgrp); - return cgrp; + return cgroup_tryget(cgrp) ? cgrp : NULL; } /** @@ -2314,7 +2313,7 @@ BTF_ID_FLAGS(func, bpf_rbtree_add) BTF_ID_FLAGS(func, bpf_rbtree_first, KF_RET_NULL) #ifdef CONFIG_CGROUPS -BTF_ID_FLAGS(func, bpf_cgroup_acquire, KF_ACQUIRE | KF_TRUSTED_ARGS) +BTF_ID_FLAGS(func, bpf_cgroup_acquire, KF_ACQUIRE | KF_RCU | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_cgroup_kptr_get, KF_ACQUIRE | KF_KPTR_GET | KF_RET_NULL) BTF_ID_FLAGS(func, bpf_cgroup_release, KF_RELEASE) BTF_ID_FLAGS(func, bpf_cgroup_ancestor, KF_ACQUIRE | KF_RCU | KF_RET_NULL) diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h b/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h index d0b7cd0d09d7..b0e279f4652b 100644 --- a/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h +++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_common.h @@ -61,6 +61,11 @@ static inline int cgrps_kfunc_map_insert(struct cgroup *cgrp) } acquired = bpf_cgroup_acquire(cgrp); + if (!acquired) { + bpf_map_delete_elem(&__cgrps_kfunc_map, &id); + return -ENOENT; + } + old = bpf_kptr_xchg(&v->cgrp, acquired); if (old) { bpf_cgroup_release(old); diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c b/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c index 48b2034cadb3..49347f12de39 100644 --- a/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c +++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_failure.c @@ -41,6 +41,23 @@ int BPF_PROG(cgrp_kfunc_acquire_untrusted, struct cgroup *cgrp, const char *path /* Can't invoke bpf_cgroup_acquire() on an untrusted pointer. */ acquired = bpf_cgroup_acquire(v->cgrp); + if (acquired) + bpf_cgroup_release(acquired); + + return 0; +} + +SEC("tp_btf/cgroup_mkdir") +__failure __msg("Possibly NULL pointer passed to trusted arg0") +int BPF_PROG(cgrp_kfunc_acquire_no_null_check, struct cgroup *cgrp, const char *path) +{ + struct cgroup *acquired; + + acquired = bpf_cgroup_acquire(cgrp); + /* + * Can't invoke bpf_cgroup_release() without checking the return value + * of bpf_cgroup_acquire(). + */ bpf_cgroup_release(acquired); return 0; @@ -54,7 +71,8 @@ int BPF_PROG(cgrp_kfunc_acquire_fp, struct cgroup *cgrp, const char *path) /* Can't invoke bpf_cgroup_acquire() on a random frame pointer. */ acquired = bpf_cgroup_acquire((struct cgroup *)&stack_cgrp); - bpf_cgroup_release(acquired); + if (acquired) + bpf_cgroup_release(acquired); return 0; } @@ -67,7 +85,8 @@ int BPF_PROG(cgrp_kfunc_acquire_unsafe_kretprobe, struct cgroup *cgrp) /* Can't acquire an untrusted struct cgroup * pointer. */ acquired = bpf_cgroup_acquire(cgrp); - bpf_cgroup_release(acquired); + if (acquired) + bpf_cgroup_release(acquired); return 0; } @@ -80,7 +99,8 @@ int BPF_PROG(cgrp_kfunc_acquire_trusted_walked, struct cgroup *cgrp, const char /* Can't invoke bpf_cgroup_acquire() on a pointer obtained from walking a trusted cgroup. */ acquired = bpf_cgroup_acquire(cgrp->old_dom_cgrp); - bpf_cgroup_release(acquired); + if (acquired) + bpf_cgroup_release(acquired); return 0; } @@ -93,9 +113,8 @@ int BPF_PROG(cgrp_kfunc_acquire_null, struct cgroup *cgrp, const char *path) /* Can't invoke bpf_cgroup_acquire() on a NULL pointer. */ acquired = bpf_cgroup_acquire(NULL); - if (!acquired) - return 0; - bpf_cgroup_release(acquired); + if (acquired) + bpf_cgroup_release(acquired); return 0; } @@ -137,6 +156,8 @@ int BPF_PROG(cgrp_kfunc_get_non_kptr_acquired, struct cgroup *cgrp, const char * struct cgroup *kptr, *acquired; acquired = bpf_cgroup_acquire(cgrp); + if (!acquired) + return 0; /* Cannot use bpf_cgroup_kptr_get() on a non-map-value, even if the kptr was acquired. */ kptr = bpf_cgroup_kptr_get(&acquired); @@ -256,6 +277,8 @@ int BPF_PROG(cgrp_kfunc_release_null, struct cgroup *cgrp, const char *path) return -ENOENT; acquired = bpf_cgroup_acquire(cgrp); + if (!acquired) + return -ENOENT; old = bpf_kptr_xchg(&v->cgrp, acquired); diff --git a/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c b/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c index 030aff700084..e9dbd1af05a7 100644 --- a/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c +++ b/tools/testing/selftests/bpf/progs/cgrp_kfunc_success.c @@ -38,7 +38,10 @@ int BPF_PROG(test_cgrp_acquire_release_argument, struct cgroup *cgrp, const char return 0; acquired = bpf_cgroup_acquire(cgrp); - bpf_cgroup_release(acquired); + if (!acquired) + err = 1; + else + bpf_cgroup_release(acquired); return 0; }