From mboxrd@z Thu Jan 1 00:00:00 1970 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=-9.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 DA3D2C3F2D2 for ; Fri, 28 Feb 2020 22:40:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A33B82469F for ; Fri, 28 Feb 2020 22:40:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="O9pB8Nss" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726751AbgB1WkE (ORCPT ); Fri, 28 Feb 2020 17:40:04 -0500 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:31628 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726621AbgB1WkC (ORCPT ); Fri, 28 Feb 2020 17:40:02 -0500 Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 01SMYggF031177 for ; Fri, 28 Feb 2020 14:40:01 -0800 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-type; s=facebook; bh=2IzERmdmX0Z8RNCsXkr/P7ZJ2EbkHQ0gftdu0lz7UJI=; b=O9pB8NssaZUXkWYC+FlnmuHh/HDVI4VGM+GUwpAdlJsBaeF7R5390V8kcjkmouHhhAUN X79OkPBM3n8uCAn+oiHNXjgNN5v9hzUjy2NFt5cWd5DdQbAqN9UtTc/lDH6ewSWLwfag StkosAnVX18HdgP8T89jv+KzuRgTCahXXOE= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 2yepvgwvv7-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Fri, 28 Feb 2020 14:40:00 -0800 Received: from intmgw001.08.frc2.facebook.com (2620:10d:c085:108::4) by mail.thefacebook.com (2620:10d:c085:11d::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1779.2; Fri, 28 Feb 2020 14:39:59 -0800 Received: by devbig012.ftw2.facebook.com (Postfix, from userid 137359) id 4E3612EC2D20; Fri, 28 Feb 2020 14:39:55 -0800 (PST) Smtp-Origin-Hostprefix: devbig From: Andrii Nakryiko Smtp-Origin-Hostname: devbig012.ftw2.facebook.com To: , , , CC: , , Andrii Nakryiko Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH bpf-next 2/3] libbpf: add bpf_link pinning/unpinning Date: Fri, 28 Feb 2020 14:39:47 -0800 Message-ID: <20200228223948.360936-3-andriin@fb.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200228223948.360936-1-andriin@fb.com> References: <20200228223948.360936-1-andriin@fb.com> X-FB-Internal: Safe MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138,18.0.572 definitions=2020-02-28_08:2020-02-28,2020-02-28 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 impostorscore=0 spamscore=0 bulkscore=0 phishscore=0 suspectscore=25 mlxscore=0 lowpriorityscore=0 adultscore=0 clxscore=1015 mlxlogscore=999 malwarescore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2002280162 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org With bpf_link abstraction supported by kernel explicitly, add pinning/unpinning API for links. Also allow to create (open) bpf_link from BPF FS file. This API allows to have an "ephemeral" FD-based BPF links (like raw tracepoint or fexit/freplace attachments) surviving user process exit, by pinning them in a BPF FS, which is an important use case for long-running BPF programs. As part of this, expose underlying FD for bpf_link. While legacy bpf_link's might not have a FD associated with them (which will be expressed as a bpf_link with fd=-1), kernel's abstraction is based around FD-based usage, so match it closely. This, subsequently, allows to have a generic pinning/unpinning API for generalized bpf_link. For some types of bpf_links kernel might not support pinning, in which case bpf_link__pin() will return error. With FD being part of generic bpf_link, also get rid of bpf_link_fd in favor of using vanialla bpf_link. Signed-off-by: Andrii Nakryiko --- tools/lib/bpf/libbpf.c | 131 +++++++++++++++++++++++++++++++-------- tools/lib/bpf/libbpf.h | 5 ++ tools/lib/bpf/libbpf.map | 5 ++ 3 files changed, 114 insertions(+), 27 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 996162801f7a..f8c4042e5855 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -6931,6 +6931,8 @@ int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr, struct bpf_link { int (*detach)(struct bpf_link *link); int (*destroy)(struct bpf_link *link); + char *pin_path; /* NULL, if not pinned */ + int fd; /* hook FD, -1 if not applicable */ bool disconnected; }; @@ -6960,26 +6962,109 @@ int bpf_link__destroy(struct bpf_link *link) err = link->detach(link); if (link->destroy) link->destroy(link); + if (link->pin_path) + free(link->pin_path); free(link); return err; } -struct bpf_link_fd { - struct bpf_link link; /* has to be at the top of struct */ - int fd; /* hook FD */ -}; +int bpf_link__fd(const struct bpf_link *link) +{ + return link->fd; +} + +const char *bpf_link__pin_path(const struct bpf_link *link) +{ + return link->pin_path; +} + +static int bpf_link__detach_fd(struct bpf_link *link) +{ + return close(link->fd); +} + +struct bpf_link *bpf_link__open(const char *path) +{ + struct bpf_link *link; + int fd; + + fd = bpf_obj_get(path); + if (fd < 0) { + fd = -errno; + pr_warn("failed to open link at %s: %d\n", path, fd); + return ERR_PTR(fd); + } + + link = calloc(1, sizeof(*link)); + if (!link) { + close(fd); + return ERR_PTR(-ENOMEM); + } + link->detach = &bpf_link__detach_fd; + link->fd = fd; + + link->pin_path = strdup(path); + if (!link->pin_path) { + bpf_link__destroy(link); + return ERR_PTR(-ENOMEM); + } + + return link; +} + +int bpf_link__pin(struct bpf_link *link, const char *path) +{ + int err; + + if (link->pin_path) + return -EBUSY; + err = make_parent_dir(path); + if (err) + return err; + err = check_path(path); + if (err) + return err; + + link->pin_path = strdup(path); + if (!link->pin_path) + return -ENOMEM; + + if (bpf_obj_pin(link->fd, link->pin_path)) { + err = -errno; + zfree(&link->pin_path); + return err; + } + + pr_debug("link fd=%d: pinned at %s\n", link->fd, link->pin_path); + return 0; +} + +int bpf_link__unpin(struct bpf_link *link) +{ + int err; + + if (!link->pin_path) + return -EINVAL; + + err = unlink(link->pin_path); + if (err != 0) + return -errno; + + pr_debug("link fd=%d: unpinned from %s\n", link->fd, link->pin_path); + zfree(&link->pin_path); + return 0; +} static int bpf_link__detach_perf_event(struct bpf_link *link) { - struct bpf_link_fd *l = (void *)link; int err; - err = ioctl(l->fd, PERF_EVENT_IOC_DISABLE, 0); + err = ioctl(link->fd, PERF_EVENT_IOC_DISABLE, 0); if (err) err = -errno; - close(l->fd); + close(link->fd); return err; } @@ -6987,7 +7072,7 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, int pfd) { char errmsg[STRERR_BUFSIZE]; - struct bpf_link_fd *link; + struct bpf_link *link; int prog_fd, err; if (pfd < 0) { @@ -7005,7 +7090,7 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, link = calloc(1, sizeof(*link)); if (!link) return ERR_PTR(-ENOMEM); - link->link.detach = &bpf_link__detach_perf_event; + link->detach = &bpf_link__detach_perf_event; link->fd = pfd; if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) { @@ -7024,7 +7109,7 @@ struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog, libbpf_strerror_r(err, errmsg, sizeof(errmsg))); return ERR_PTR(err); } - return (struct bpf_link *)link; + return link; } /* @@ -7312,18 +7397,11 @@ static struct bpf_link *attach_tp(const struct bpf_sec_def *sec, return link; } -static int bpf_link__detach_fd(struct bpf_link *link) -{ - struct bpf_link_fd *l = (void *)link; - - return close(l->fd); -} - struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog, const char *tp_name) { char errmsg[STRERR_BUFSIZE]; - struct bpf_link_fd *link; + struct bpf_link *link; int prog_fd, pfd; prog_fd = bpf_program__fd(prog); @@ -7336,7 +7414,7 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog, link = calloc(1, sizeof(*link)); if (!link) return ERR_PTR(-ENOMEM); - link->link.detach = &bpf_link__detach_fd; + link->detach = &bpf_link__detach_fd; pfd = bpf_raw_tracepoint_open(tp_name, prog_fd); if (pfd < 0) { @@ -7348,7 +7426,7 @@ struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog, return ERR_PTR(pfd); } link->fd = pfd; - return (struct bpf_link *)link; + return link; } static struct bpf_link *attach_raw_tp(const struct bpf_sec_def *sec, @@ -7362,7 +7440,7 @@ static struct bpf_link *attach_raw_tp(const struct bpf_sec_def *sec, struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog) { char errmsg[STRERR_BUFSIZE]; - struct bpf_link_fd *link; + struct bpf_link *link; int prog_fd, pfd; prog_fd = bpf_program__fd(prog); @@ -7375,7 +7453,7 @@ struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog) link = calloc(1, sizeof(*link)); if (!link) return ERR_PTR(-ENOMEM); - link->link.detach = &bpf_link__detach_fd; + link->detach = &bpf_link__detach_fd; pfd = bpf_raw_tracepoint_open(NULL, prog_fd); if (pfd < 0) { @@ -7409,10 +7487,9 @@ struct bpf_link *bpf_program__attach(struct bpf_program *prog) static int bpf_link__detach_struct_ops(struct bpf_link *link) { - struct bpf_link_fd *l = (void *)link; __u32 zero = 0; - if (bpf_map_delete_elem(l->fd, &zero)) + if (bpf_map_delete_elem(link->fd, &zero)) return -errno; return 0; @@ -7421,7 +7498,7 @@ static int bpf_link__detach_struct_ops(struct bpf_link *link) struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map) { struct bpf_struct_ops *st_ops; - struct bpf_link_fd *link; + struct bpf_link *link; __u32 i, zero = 0; int err; @@ -7453,10 +7530,10 @@ struct bpf_link *bpf_map__attach_struct_ops(struct bpf_map *map) return ERR_PTR(err); } - link->link.detach = bpf_link__detach_struct_ops; + link->detach = bpf_link__detach_struct_ops; link->fd = map->fd; - return (struct bpf_link *)link; + return link; } enum bpf_perf_event_ret diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index 02fc58a21a7f..d38d7a629417 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -219,6 +219,11 @@ LIBBPF_API void bpf_program__unload(struct bpf_program *prog); struct bpf_link; +LIBBPF_API struct bpf_link *bpf_link__open(const char *path); +LIBBPF_API int bpf_link__fd(const struct bpf_link *link); +LIBBPF_API const char *bpf_link__pin_path(const struct bpf_link *link); +LIBBPF_API int bpf_link__pin(struct bpf_link *link, const char *path); +LIBBPF_API int bpf_link__unpin(struct bpf_link *link); LIBBPF_API void bpf_link__disconnect(struct bpf_link *link); LIBBPF_API int bpf_link__destroy(struct bpf_link *link); diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map index 7b014c8cdece..5129283c0284 100644 --- a/tools/lib/bpf/libbpf.map +++ b/tools/lib/bpf/libbpf.map @@ -238,5 +238,10 @@ LIBBPF_0.0.7 { LIBBPF_0.0.8 { global: + bpf_link__fd; + bpf_link__open; + bpf_link__pin; + bpf_link__pin_path; + bpf_link__unpin; bpf_program__set_attach_target; } LIBBPF_0.0.7; -- 2.17.1