From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-174.mta1.migadu.com (out-174.mta1.migadu.com [95.215.58.174]) (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 0E75E226883 for ; Thu, 19 Dec 2024 16:11:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734624694; cv=none; b=PzE5lfiV1sMaxe3gT3LD3SKGf3q1yk5IyAepETKNlNfleR6ZAZnwBfLTWeK3xgteyk88SgCx2r9lx1SzA8dN/KXIsIra2Wl0pT/dsOM5pDZOj2iZodiYiNx+YtmSV4BrqBATXTOVbZ2sPZqQcwoQlQOPpjdc3p28ZRFc64tHEVg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734624694; c=relaxed/simple; bh=mWVH3rAsk5h3ckz3gNoSdBBBTkSCZ9BSG+hyNch2g3g=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=aL5L6ICBUEQO9oMpBbe8btj2UivEg8kAgWrGEP2Z8JZmoFQ/ZlOMcQ7hbTam8ahx2z2JvaMrALQkdQiB2RO4uOvPMtjyhHhg56SZ73vQIQ+9yhHuqwGmc5skm4gRpZs3cIYzTuwwkebk3KkeFZVwVhSWtiPVGwMKe7b4jXH4IOQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=XM249I5r; arc=none smtp.client-ip=95.215.58.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="XM249I5r" Message-ID: <09256acb-9b23-4a25-a260-a4063d219899@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1734624681; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=7UovLRK5y6ohnM8T6CZvegkTaxuziaYqQQ/0lf+o36A=; b=XM249I5r/a0K+DJ29HlMkFWuV4T21RQctWitV/3T5jB/4TT6oTCtBGNj4pzVQmZ4Jnt4xg FdYee6uZZm9ZTSdMzHIyBVDfpqMT4mkqMHfNXukGuzuCekg+e71YJXPY4auBkslde62N1Q 6AaNqDiZlu3OwK6eJi+0lsrNKioTzIw= Date: Thu, 19 Dec 2024 08:11:12 -0800 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v6 0/5] bpf: Add open-coded style process file iterator and bpf_fget_task() kfunc Content-Language: en-GB To: Juntong Deng , ast@kernel.org, daniel@iogearbox.net, john.fastabend@gmail.com, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, memxor@gmail.com, snorcht@gmail.com, brauner@kernel.org Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 12/17/24 3:34 PM, Juntong Deng wrote: > This patch series adds open-coded style process file iterator > bpf_iter_task_file and bpf_fget_task() kfunc, and corresponding > selftests test cases. > > In addition, since fs kfuncs is generic and useful for scenarios > other than LSM, this patch makes fs kfuncs available for SYSCALL > program type. > > Although iter/task_file already exists, for CRIB we still need the > open-coded iterator style process file iterator, and the same is true > for other bpf iterators such as iter/tcp, iter/udp, etc. > > The traditional bpf iterator is more like a bpf version of procfs, but > similar to procfs, it is not suitable for CRIB scenarios that need to > obtain large amounts of complex, multi-level in-kernel information. > > The following is from previous discussions [1]. > > [1]: https://lore.kernel.org/bpf/AM6PR03MB5848CA34B5B68C90F210285E99B12@AM6PR03MB5848.eurprd03.prod.outlook.com/ > > This is because the context of bpf iterators is fixed and bpf iterators > cannot be nested. This means that a bpf iterator program can only > complete a specific small iterative dump task, and cannot dump > multi-level data. > > An example, when we need to dump all the sockets of a process, we need > to iterate over all the files (sockets) of the process, and iterate over > the all packets in the queue of each socket, and iterate over all data > in each packet. > > If we use bpf iterator, since the iterator can not be nested, we need to > use socket iterator program to get all the basic information of all > sockets (pass pid as filter), and then use packet iterator program to > get the basic information of all packets of a specific socket (pass pid, > fd as filter), and then use packet data iterator program to get all the > data of a specific packet (pass pid, fd, packet index as filter). > > This would be complicated and require a lot of (each iteration) > bpf program startup and exit (leading to poor performance). > > By comparison, open coded iterator is much more flexible, we can iterate > in any context, at any time, and iteration can be nested, so we can > achieve more flexible and more elegant dumping through open coded > iterators. > > With open coded iterators, all of the above can be done in a single > bpf program, and with nested iterators, everything becomes compact > and simple. > > Also, bpf iterators transmit data to user space through seq_file, > which involves a lot of open (bpf_iter_create), read, close syscalls, > context switching, memory copying, and cannot achieve the performance > of using ringbuf. > > Signed-off-by: Juntong Deng > --- > v5 -> v6: > * Remove local variable in bpf_fget_task. > > * Remove KF_RCU_PROTECTED from bpf_iter_task_file_new. > > * Remove bpf_fs_kfunc_set from being available for TRACING. > > * Use get_task_struct in bpf_iter_task_file_new. > > * Use put_task_struct in bpf_iter_task_file_destroy. > > v4 -> v5: > * Add file type checks in test cases for process file iterator > and bpf_fget_task(). > > * Use fentry to synchronize tests instead of waiting in a loop. > > * Remove path_d_path_kfunc_non_lsm test case. > > * Replace task_lookup_next_fdget_rcu() with fget_task_next(). > > * Remove future merge conflict section in cover letter (resolved). > > v3 -> v4: > * Make all kfuncs generic, not CRIB specific. > > * Move bpf_fget_task to fs/bpf_fs_kfuncs.c. > > * Remove bpf_iter_task_file_get_fd and bpf_get_file_ops_type. > > * Use struct bpf_iter_task_file_item * as the return value of > bpf_iter_task_file_next. > > * Change fd to unsigned int type and add next_fd. > > * Add KF_RCU_PROTECTED to bpf_iter_task_file_new. > > * Make fs kfuncs available to SYSCALL and TRACING program types. > > * Update all relevant test cases. > > * Remove the discussion section from cover letter. > > v2 -> v3: > * Move task_file open-coded iterator to kernel/bpf/helpers.c. > > * Fix duplicate error code 7 in test_bpf_iter_task_file(). > > * Add comment for case when bpf_iter_task_file_get_fd() returns -1. > > * Add future plans in commit message of "Add struct file related > CRIB kfuncs". > > * Add Discussion section to cover letter. > > v1 -> v2: > * Fix a type definition error in the fd parameter of > bpf_fget_task() at crib_common.h. > > Juntong Deng (5): > bpf: Introduce task_file open-coded iterator kfuncs > selftests/bpf: Add tests for open-coded style process file iterator > bpf: Add bpf_fget_task() kfunc > bpf: Make fs kfuncs available for SYSCALL program type > selftests/bpf: Add tests for bpf_fget_task() kfunc > > fs/bpf_fs_kfuncs.c | 38 ++++---- > kernel/bpf/helpers.c | 3 + > kernel/bpf/task_iter.c | 91 +++++++++++++++++++ > .../testing/selftests/bpf/bpf_experimental.h | 15 +++ > .../selftests/bpf/prog_tests/fs_kfuncs.c | 46 ++++++++++ > .../testing/selftests/bpf/prog_tests/iters.c | 79 ++++++++++++++++ > .../selftests/bpf/progs/fs_kfuncs_failure.c | 33 +++++++ > .../selftests/bpf/progs/iters_task_file.c | 86 ++++++++++++++++++ > .../bpf/progs/iters_task_file_failure.c | 91 +++++++++++++++++++ > .../selftests/bpf/progs/test_fget_task.c | 63 +++++++++++++ > .../selftests/bpf/progs/verifier_vfs_reject.c | 10 -- > 11 files changed, 529 insertions(+), 26 deletions(-) > create mode 100644 tools/testing/selftests/bpf/progs/fs_kfuncs_failure.c > create mode 100644 tools/testing/selftests/bpf/progs/iters_task_file.c > create mode 100644 tools/testing/selftests/bpf/progs/iters_task_file_failure.c > create mode 100644 tools/testing/selftests/bpf/progs/test_fget_task.c There are quite some CI failures.    https://github.com/kernel-patches/bpf/actions/runs/12403224240/job/34626610882?pr=8266 Please investigate.