From patchwork Wed Jul 22 21:12:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Olsa X-Patchwork-Id: 1334179 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=none dis=none) header.from=kernel.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BBp8m4FnZz9sR4 for ; Thu, 23 Jul 2020 07:13:12 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732983AbgGVVNL convert rfc822-to-8bit (ORCPT ); Wed, 22 Jul 2020 17:13:11 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:51239 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1732957AbgGVVNK (ORCPT ); Wed, 22 Jul 2020 17:13:10 -0400 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-303-9FmeUw2cM1iMPhEfRGyPfg-1; Wed, 22 Jul 2020 17:13:04 -0400 X-MC-Unique: 9FmeUw2cM1iMPhEfRGyPfg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 04EF0185BE02; Wed, 22 Jul 2020 21:13:02 +0000 (UTC) Received: from krava.redhat.com (unknown [10.40.194.40]) by smtp.corp.redhat.com (Postfix) with ESMTP id F309519C4F; Wed, 22 Jul 2020 21:12:58 +0000 (UTC) From: Jiri Olsa To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: netdev@vger.kernel.org, bpf@vger.kernel.org, Song Liu , Yonghong Song , Martin KaFai Lau , David Miller , John Fastabend , Wenbo Zhang , KP Singh , Brendan Gregg , Florent Revest , Al Viro Subject: [PATCH v8 bpf-next 09/13] bpf: Add d_path helper Date: Wed, 22 Jul 2020 23:12:19 +0200 Message-Id: <20200722211223.1055107-10-jolsa@kernel.org> In-Reply-To: <20200722211223.1055107-1-jolsa@kernel.org> References: <20200722211223.1055107-1-jolsa@kernel.org> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: kernel.org Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Adding d_path helper function that returns full path for given 'struct path' object, which needs to be the kernel BTF 'path' object. The path is returned in buffer provided 'buf' of size 'sz' and is zero terminated. bpf_d_path(&file->f_path, buf, size); The helper calls directly d_path function, so there's only limited set of function it can be called from. Adding just very modest set for the start. Updating also bpf.h tools uapi header and adding 'path' to bpf_helpers_doc.py script. Signed-off-by: Jiri Olsa --- include/uapi/linux/bpf.h | 13 +++++++++ kernel/trace/bpf_trace.c | 48 ++++++++++++++++++++++++++++++++++ scripts/bpf_helpers_doc.py | 2 ++ tools/include/uapi/linux/bpf.h | 13 +++++++++ 4 files changed, 76 insertions(+) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 54d0c886e3ba..f8341219b5ea 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3377,6 +3377,18 @@ union bpf_attr { * A non-negative value equal to or less than *size* on success, * or a negative error in case of failure. * + * int bpf_d_path(struct path *path, char *buf, u32 sz) + * Description + * Return full path for given 'struct path' object, which + * needs to be the kernel BTF 'path' object. The path is + * returned in buffer provided 'buf' of size 'sz' and + * is zero terminated. + * + * Return + * On success, the strictly positive length of the string, + * including the trailing NUL character. On error, a negative + * value. + * */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3521,6 +3533,7 @@ union bpf_attr { FN(skc_to_tcp_request_sock), \ FN(skc_to_udp6_sock), \ FN(get_task_stack), \ + FN(d_path), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 3cc0dcb60ca2..0488db62aaaf 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1098,6 +1098,52 @@ static const struct bpf_func_proto bpf_send_signal_thread_proto = { .arg1_type = ARG_ANYTHING, }; +BPF_CALL_3(bpf_d_path, struct path *, path, char *, buf, u32, sz) +{ + char *p = d_path(path, buf, sz - 1); + int len; + + if (IS_ERR(p)) { + len = PTR_ERR(p); + } else { + len = strlen(p); + if (len && p != buf) + memmove(buf, p, len); + buf[len] = 0; + /* Include the trailing NUL. */ + len++; + } + + return len; +} + +BTF_SET_START(btf_whitelist_d_path) +BTF_ID(func, vfs_truncate) +BTF_ID(func, vfs_fallocate) +BTF_ID(func, dentry_open) +BTF_ID(func, vfs_getattr) +BTF_ID(func, filp_close) +BTF_SET_END(btf_whitelist_d_path) + +static bool bpf_d_path_allowed(const struct bpf_prog *prog) +{ + return btf_id_set_contains(&btf_whitelist_d_path, prog->aux->attach_btf_id); +} + +BTF_ID_LIST(bpf_d_path_btf_ids) +BTF_ID(struct, path) + +static const struct bpf_func_proto bpf_d_path_proto = { + .func = bpf_d_path, + .gpl_only = false, + .ret_type = RET_INTEGER, + .arg1_type = ARG_PTR_TO_BTF_ID, + .arg2_type = ARG_PTR_TO_MEM, + .arg3_type = ARG_CONST_SIZE, + .btf_id = bpf_d_path_btf_ids, + .allowed = bpf_d_path_allowed, +}; + const struct bpf_func_proto * bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { @@ -1579,6 +1625,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) return prog->expected_attach_type == BPF_TRACE_ITER ? &bpf_seq_write_proto : NULL; + case BPF_FUNC_d_path: + return &bpf_d_path_proto; default: return raw_tp_prog_func_proto(func_id, prog); } diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py index 5bfa448b4704..08388173973f 100755 --- a/scripts/bpf_helpers_doc.py +++ b/scripts/bpf_helpers_doc.py @@ -432,6 +432,7 @@ class PrinterHelpers(Printer): 'struct __sk_buff', 'struct sk_msg_md', 'struct xdp_md', + 'struct path', ] known_types = { '...', @@ -472,6 +473,7 @@ class PrinterHelpers(Printer): 'struct tcp_request_sock', 'struct udp6_sock', 'struct task_struct', + 'struct path', } mapped_types = { 'u8': '__u8', diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index 54d0c886e3ba..f8341219b5ea 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -3377,6 +3377,18 @@ union bpf_attr { * A non-negative value equal to or less than *size* on success, * or a negative error in case of failure. * + * int bpf_d_path(struct path *path, char *buf, u32 sz) + * Description + * Return full path for given 'struct path' object, which + * needs to be the kernel BTF 'path' object. The path is + * returned in buffer provided 'buf' of size 'sz' and + * is zero terminated. + * + * Return + * On success, the strictly positive length of the string, + * including the trailing NUL character. On error, a negative + * value. + * */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3521,6 +3533,7 @@ union bpf_attr { FN(skc_to_tcp_request_sock), \ FN(skc_to_udp6_sock), \ FN(get_task_stack), \ + FN(d_path), \ /* */ /* integer value in 'imm' field of BPF_CALL instruction selects which helper