From patchwork Mon Mar 8 17:06:40 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kalesh Singh X-Patchwork-Id: 12122979 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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 E8BC7C433E9 for ; Mon, 8 Mar 2021 17:08:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF32B65230 for ; Mon, 8 Mar 2021 17:08:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230475AbhCHRHt (ORCPT ); Mon, 8 Mar 2021 12:07:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34766 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230002AbhCHRHQ (ORCPT ); Mon, 8 Mar 2021 12:07:16 -0500 Received: from mail-qv1-xf49.google.com (mail-qv1-xf49.google.com [IPv6:2607:f8b0:4864:20::f49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 52AC1C06175F for ; Mon, 8 Mar 2021 09:07:16 -0800 (PST) Received: by mail-qv1-xf49.google.com with SMTP id dz17so8128831qvb.14 for ; Mon, 08 Mar 2021 09:07:16 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:message-id:mime-version:subject:from:cc; bh=7mCRpmhv1OM36vNlkAtqHtWEhlUKPQI2C+wk9QTsT80=; b=miOOpv1RLxFINJF7EYHrzJzD3khYSf16V5pPLLmhxznHshwiurgylwUbtsXLx/GoPJ E4qC1svZwWEj/bXdNmvg5CGJzUHhR5Y9P9OWIatPV1Ja2AyN/hzWec0bxrfow92fYY3I EpUzhabEWV2Kblsu3IglcUnYAOLa0xlESIWPOBFI4z3hnpejjSlW5DbJGEI7VwZB5XmI 5VcR6tW/GZjaU5fOBzMzt8dod0HiT/b0wdReP0Pq7fe19dWJm7pOfW5ZKGdY5EV9lGTm fi0JUcAaB3pzkbmBwgyZAkRBDTIsAFXVLxwO8LLHSY8lp0UhE7gIQP2x5JvqDYEj/6IS cJ/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:message-id:mime-version:subject:from :cc; bh=7mCRpmhv1OM36vNlkAtqHtWEhlUKPQI2C+wk9QTsT80=; b=s+LhJeCP5vEp4oivFTnlq53Q6ud4R4dXV+tbmXAW8hoMgS80FTzvX9+oAVYdKoPnd7 7mexqdqhCNB/c//Uv94iLPItcPRhWZjz0oaePzS/aZsalLa+KiA0QtLauUFNxhLHa2WQ zn8kRWGOURjRJq4IzvMSvGR23PU5mZ6yoZ/6pCqX+6DmFymuIvQqLFeaGIFcEa6nSbi6 cY/abut69sxSFFprLnXoU3XTm/y8k6eBuktH3qM2v5tnuPzfzBbypYU/cOQ1wnscjKmx qL4xJuULIIWq7q739QUogELkvx+Oujt/pE7iLD3+D3AEUKzaxprtlzBZfjnVXxa0vbvV d+QA== X-Gm-Message-State: AOAM5313jChFhRmrQLVpOYN51kpsT2EVdAW0rWmu/bNR5O27sotcCzy/ P2xHDF6UerjzUc6YHoTqiVkn/pnOZxilAiAkTw== X-Google-Smtp-Source: ABdhPJx9+q+MEXXOho3t/3yQ+LqETPemrMlYxWkhxLoiKwMhnO2xsjvoochQa6vlE3++weFzUkrdxqvsxq+Dbq6zpA== Sender: "kaleshsingh via sendgmr" X-Received: from kaleshsingh.c.googlers.com ([fda3:e722:ac3:10:14:4d90:c0a8:2145]) (user=kaleshsingh job=sendgmr) by 2002:a0c:b526:: with SMTP id d38mr21324197qve.7.1615223235257; Mon, 08 Mar 2021 09:07:15 -0800 (PST) Date: Mon, 8 Mar 2021 17:06:40 +0000 Message-Id: <20210308170651.919148-1-kaleshsingh@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.30.1.766.gb4fecdf3b7-goog Subject: [RESEND PATCH v6 1/2] procfs: Allow reading fdinfo with PTRACE_MODE_READ From: Kalesh Singh Cc: jannh@google.com, jeffv@google.com, keescook@chromium.org, surenb@google.com, minchan@kernel.org, hridya@google.com, rdunlap@infradead.org, christian.koenig@amd.com, willy@infradead.org, viro@zeniv.linux.org.uk, kernel-team@android.com, Kalesh Singh , Alexey Dobriyan , Jonathan Corbet , Andrew Morton , Mauro Carvalho Chehab , Michal Hocko , Alexey Gladkov , Szabolcs Nagy , "Eric W. Biederman" , Christian Brauner , Michel Lespinasse , Bernd Edlinger , Andrei Vagin , Helge Deller , James Morris , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Android captures per-process system memory state when certain low memory events (e.g a foreground app kill) occur, to identify potential memory hoggers. In order to measure how much memory a process actually consumes, it is necessary to include the DMA buffer sizes for that process in the memory accounting. Since the handle to DMA buffers are raw FDs, it is important to be able to identify which processes have FD references to a DMA buffer. Currently, DMA buffer FDs can be accounted using /proc//fd/* and /proc//fdinfo -- both are only readable by the process owner, as follows: 1. Do a readlink on each FD. 2. If the target path begins with "/dmabuf", then the FD is a dmabuf FD. 3. stat the file to get the dmabuf inode number. 4. Read/ proc//fdinfo/, to get the DMA buffer size. Accessing other processes' fdinfo requires root privileges. This limits the use of the interface to debugging environments and is not suitable for production builds. Granting root privileges even to a system process increases the attack surface and is highly undesirable. Since fdinfo doesn't permit reading process memory and manipulating process state, allow accessing fdinfo under PTRACE_MODE_READ_FSCRED. Suggested-by: Jann Horn Signed-off-by: Kalesh Singh Reviewed-by: Kees Cook --- Hi everyone, The initial posting of this patch can be found at [1]. I didn't receive any feedback last time, so resending here. Would really appreciate any constructive comments/suggestions. Thanks, Kalesh [1] https://lore.kernel.org/r/20210208155315.1367371-1-kaleshsingh@google.com/ Changes in v2: - Update patch description fs/proc/base.c | 4 ++-- fs/proc/fd.c | 15 ++++++++++++++- 2 files changed, 16 insertions(+), 3 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 3851bfcdba56..fd46d8dd0cf4 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -3159,7 +3159,7 @@ static const struct pid_entry tgid_base_stuff[] = { DIR("task", S_IRUGO|S_IXUGO, proc_task_inode_operations, proc_task_operations), DIR("fd", S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations), DIR("map_files", S_IRUSR|S_IXUSR, proc_map_files_inode_operations, proc_map_files_operations), - DIR("fdinfo", S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations), + DIR("fdinfo", S_IRUGO|S_IXUGO, proc_fdinfo_inode_operations, proc_fdinfo_operations), DIR("ns", S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations), #ifdef CONFIG_NET DIR("net", S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations), @@ -3504,7 +3504,7 @@ static const struct inode_operations proc_tid_comm_inode_operations = { */ static const struct pid_entry tid_base_stuff[] = { DIR("fd", S_IRUSR|S_IXUSR, proc_fd_inode_operations, proc_fd_operations), - DIR("fdinfo", S_IRUSR|S_IXUSR, proc_fdinfo_inode_operations, proc_fdinfo_operations), + DIR("fdinfo", S_IRUGO|S_IXUGO, proc_fdinfo_inode_operations, proc_fdinfo_operations), DIR("ns", S_IRUSR|S_IXUGO, proc_ns_dir_inode_operations, proc_ns_dir_operations), #ifdef CONFIG_NET DIR("net", S_IRUGO|S_IXUGO, proc_net_inode_operations, proc_net_operations), diff --git a/fs/proc/fd.c b/fs/proc/fd.c index 07fc4fad2602..6a80b40fd2fe 100644 --- a/fs/proc/fd.c +++ b/fs/proc/fd.c @@ -6,6 +6,7 @@ #include #include #include +#include #include #include #include @@ -72,6 +73,18 @@ static int seq_show(struct seq_file *m, void *v) static int seq_fdinfo_open(struct inode *inode, struct file *file) { + bool allowed = false; + struct task_struct *task = get_proc_task(inode); + + if (!task) + return -ESRCH; + + allowed = ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS); + put_task_struct(task); + + if (!allowed) + return -EACCES; + return single_open(file, seq_show, inode); } @@ -308,7 +321,7 @@ static struct dentry *proc_fdinfo_instantiate(struct dentry *dentry, struct proc_inode *ei; struct inode *inode; - inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUSR); + inode = proc_pid_make_inode(dentry->d_sb, task, S_IFREG | S_IRUGO); if (!inode) return ERR_PTR(-ENOENT); From patchwork Mon Mar 8 17:06:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kalesh Singh X-Patchwork-Id: 12122981 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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, 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,USER_IN_DEF_DKIM_WL 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 46A74C4332E for ; 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Mon, 08 Mar 2021 09:07:28 -0800 (PST) Date: Mon, 8 Mar 2021 17:06:41 +0000 In-Reply-To: <20210308170651.919148-1-kaleshsingh@google.com> Message-Id: <20210308170651.919148-2-kaleshsingh@google.com> Mime-Version: 1.0 References: <20210308170651.919148-1-kaleshsingh@google.com> X-Mailer: git-send-email 2.30.1.766.gb4fecdf3b7-goog Subject: [RESEND PATCH v6 2/2] procfs/dmabuf: Add inode number to /proc/*/fdinfo From: Kalesh Singh Cc: jannh@google.com, jeffv@google.com, keescook@chromium.org, surenb@google.com, minchan@kernel.org, hridya@google.com, rdunlap@infradead.org, christian.koenig@amd.com, willy@infradead.org, viro@zeniv.linux.org.uk, kernel-team@android.com, Kalesh Singh , Alexey Dobriyan , Jonathan Corbet , Andrew Morton , Michal Hocko , Mauro Carvalho Chehab , Alexey Gladkov , "Eric W. Biederman" , Christian Brauner , Michel Lespinasse , Bernd Edlinger , Andrei Vagin , Helge Deller , James Morris , Serge Hallyn , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org And 'ino' field to /proc//fdinfo/ and /proc//task//fdinfo/. The inode numbers can be used to uniquely identify DMA buffers in user space and avoids a dependency on /proc//fd/* when accounting per-process DMA buffer sizes. Signed-off-by: Kalesh Singh Acked-by: Randy Dunlap Reviewed-by: Kees Cook --- Hi everyone, This a resend of the inital posting at [1]. There was no objections on the last threads, along with some positive feedback from Randy. If there is no other concern I would like to have this considered for mainline. Thanks, Kalesh [1] https://lore.kernel.org/linux-doc/20210208155315.1367371-2-kaleshsingh@google.com/ Changes in v5: - Fixed tab vs spaces, per Randy - Renamed inode_no to ino, per Matthew Changes in v4: - Add inode number as common field in fdinfo, per Christian Changes in v3: - Add documentation in proc.rst, per Randy Changes in v2: - Update patch description --- Documentation/filesystems/proc.rst | 37 +++++++++++++++++++++++++----- fs/proc/fd.c | 5 ++-- 2 files changed, 34 insertions(+), 8 deletions(-) diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 48fbfc336ebf..33d08fbb0022 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -1909,18 +1909,20 @@ if precise results are needed. 3.8 /proc//fdinfo/ - Information about opened file --------------------------------------------------------------- This file provides information associated with an opened file. The regular -files have at least three fields -- 'pos', 'flags' and 'mnt_id'. The 'pos' -represents the current offset of the opened file in decimal form [see lseek(2) -for details], 'flags' denotes the octal O_xxx mask the file has been -created with [see open(2) for details] and 'mnt_id' represents mount ID of -the file system containing the opened file [see 3.5 /proc//mountinfo -for details]. +files have at least four fields -- 'pos', 'flags', 'mnt_id' and 'ino'. +The 'pos' represents the current offset of the opened file in decimal +form [see lseek(2) for details], 'flags' denotes the octal O_xxx mask the +file has been created with [see open(2) for details] and 'mnt_id' represents +mount ID of the file system containing the opened file [see 3.5 +/proc//mountinfo for details]. 'ino' represents the inode number of +the file. A typical output is:: pos: 0 flags: 0100002 mnt_id: 19 + ino: 63107 All locks associated with a file descriptor are shown in its fdinfo too:: @@ -1937,6 +1939,7 @@ Eventfd files pos: 0 flags: 04002 mnt_id: 9 + ino: 63107 eventfd-count: 5a where 'eventfd-count' is hex value of a counter. @@ -1949,6 +1952,7 @@ Signalfd files pos: 0 flags: 04002 mnt_id: 9 + ino: 63107 sigmask: 0000000000000200 where 'sigmask' is hex value of the signal mask associated @@ -1962,6 +1966,7 @@ Epoll files pos: 0 flags: 02 mnt_id: 9 + ino: 63107 tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7 where 'tfd' is a target file descriptor number in decimal form, @@ -1978,6 +1983,8 @@ For inotify files the format is the following:: pos: 0 flags: 02000000 + mnt_id: 9 + ino: 63107 inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d where 'wd' is a watch descriptor in decimal form, i.e. a target file @@ -2000,6 +2007,7 @@ For fanotify files the format is:: pos: 0 flags: 02 mnt_id: 9 + ino: 63107 fanotify flags:10 event-flags:0 fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003 fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4 @@ -2024,6 +2032,7 @@ Timerfd files pos: 0 flags: 02 mnt_id: 9 + ino: 63107 clockid: 0 ticks: 0 settime flags: 01 @@ -2038,6 +2047,22 @@ details]. 'it_value' is remaining time until the timer expiration. with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value' still exhibits timer's remaining time. +DMA Buffer files +~~~~~~~~~~~~~~~~ + +:: + + pos: 0 + flags: 04002 + mnt_id: 9 + ino: 63107 + size: 32768 + count: 2 + exp_name: system-heap + +where 'size' is the size of the DMA buffer in bytes. 'count' is the file count of +the DMA buffer file. 'exp_name' is the name of the DMA buffer exporter. + 3.9 /proc//map_files - Information about memory mapped files --------------------------------------------------------------------- This directory contains symbolic links which represent memory mapped files diff --git a/fs/proc/fd.c b/fs/proc/fd.c index 6a80b40fd2fe..172c86270b31 100644 --- a/fs/proc/fd.c +++ b/fs/proc/fd.c @@ -54,9 +54,10 @@ static int seq_show(struct seq_file *m, void *v) if (ret) return ret; - seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\n", + seq_printf(m, "pos:\t%lli\nflags:\t0%o\nmnt_id:\t%i\nino:\t%lu\n", (long long)file->f_pos, f_flags, - real_mount(file->f_path.mnt)->mnt_id); + real_mount(file->f_path.mnt)->mnt_id, + file_inode(file)->i_ino); /* show_fd_locks() never deferences files so a stale value is safe */ show_fd_locks(m, file, files);