From patchwork Thu Jun 23 22:06:07 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kalesh Singh X-Patchwork-Id: 12893230 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 78321CCA47C for ; Thu, 23 Jun 2022 22:06:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230109AbiFWWGs (ORCPT ); Thu, 23 Jun 2022 18:06:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44470 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230050AbiFWWGq (ORCPT ); Thu, 23 Jun 2022 18:06:46 -0400 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C1B9F5DF2A for ; Thu, 23 Jun 2022 15:06:44 -0700 (PDT) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-317a4c8a662so6188517b3.6 for ; Thu, 23 Jun 2022 15:06:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=a2jg4UNQjviND3cH82kQJDjQu+6LwBTunrM4AXOvyQQ=; b=GEqvezpitihwD1TDcPv/qNvBJOGfHHvcsuOZN512C3aYaCbS2r8hGXoqtFxTRaWRPH ONl8vk6GXcTdTullSPSHeTQweqyptRyDMrz7r+0cehuL7f+HmxtyScPTTrul+ODzkU6L NNk4Vd1huXBU/7OvU6cGpVx4N3IU6SgKjursyVHLc4xxYcLhKjxJyinTqR4Fi9oPvCLO nVTMvb5EyVfxqZjUt2LvIg1y6pPENDp1ltIZFCXzKN1tnYrOaBZRHd3IuXe3LgYYeRu4 /dBMfFa7gyn9Fytx1/ODtSwfTOswRSRgxTFFAOki5A2+kW24OVc+8kXSBb2/tk8MvIsE EHFA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=a2jg4UNQjviND3cH82kQJDjQu+6LwBTunrM4AXOvyQQ=; b=N+GZMQN4XDknQrJQoXiFjJrJmzIgW08VMnptnm3Xgf1sqhQMFU5vuS+52bNlOc4Vh8 8sOdM5jnae9B6diiMXKAWJ+8POI5f0oDxANwSW+901t2WEYzUqaLlnEjLVuADOWdrOGI 9fVg/81jWrXo22tLxssKghY1UqDDpNBomDEmlqgOFMTamgD/oUCGEptik5+MuLAHCBgJ gQ7lvdTP5aWJQo7afdmFsHeMy/licn/N5xCNIB/eTlSnqT1xzv+D1Kpp6NGJNPo2Ky/n j7B6cNDmnuhQD92IyaqyrK+qv3xDfP9m/UFMqqULTL85ymH9N+UcvJ5tRpUYtiGlA9vG jE+w== X-Gm-Message-State: AJIora+iJogsaTqiUV291DySmuqI0iWe75diuiYQSFvPm4O9aiI2q/Jt 6Q1NtEydKSuADvnqaGlVHjnZMbt+WuEevaXysg== X-Google-Smtp-Source: AGRyM1vSTrTtNaDILcKLNUvdvxUtr0gmEZ7meLNus5pJkbvDd0DxxtAacCrYBtze6AGzcMMeOrwshzpBaYuShELJSQ== X-Received: from kaleshsingh.mtv.corp.google.com ([2620:15c:211:200:ac62:20a7:e3c5:c221]) (user=kaleshsingh job=sendgmr) by 2002:a0d:c482:0:b0:317:8bf3:f07f with SMTP id g124-20020a0dc482000000b003178bf3f07fmr13205255ywd.11.1656022003907; Thu, 23 Jun 2022 15:06:43 -0700 (PDT) Date: Thu, 23 Jun 2022 15:06:07 -0700 In-Reply-To: <20220623220613.3014268-1-kaleshsingh@google.com> Message-Id: <20220623220613.3014268-3-kaleshsingh@google.com> Mime-Version: 1.0 References: <20220623220613.3014268-1-kaleshsingh@google.com> X-Mailer: git-send-email 2.37.0.rc0.161.g10f37bed90-goog Subject: [PATCH v2 2/2] procfs: Add 'path' to /proc//fdinfo/ From: Kalesh Singh To: ckoenig.leichtzumerken@gmail.com, christian.koenig@amd.com, viro@zeniv.linux.org.uk, hch@infradead.org, stephen.s.brennan@oracle.com, David.Laight@ACULAB.COM Cc: ilkos@google.com, tjmercier@google.com, surenb@google.com, kernel-team@android.com, Kalesh Singh , Jonathan Corbet , Sumit Semwal , Andrew Morton , Johannes Weiner , Christoph Anton Mitterer , Colin Cross , Paul Gortmaker , Randy Dunlap , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org In order to identify the type of memory a process has pinned through its open fds, add the file path to fdinfo output. This allows identifying memory types based on common prefixes: e.g. "/memfd...", "/dmabuf...", "/dev/ashmem...". To be cautious, only expose the paths for anonymous inodes, and this also avoids printing path names with strange characters. Access to /proc//fdinfo is governed by PTRACE_MODE_READ_FSCREDS the same as /proc//maps which also exposes the file path of mappings; so the security permissions for accessing path is consistent with that of /proc//maps. Signed-off-by: Kalesh Singh --- Changes in v2: - Only add path field for files with anon inodes. Changes from rfc: - Split adding 'size' and 'path' into a separate patches, per Christian - Fix indentation (use tabs) in documentaion, per Randy Documentation/filesystems/proc.rst | 10 ++++++++++ fs/libfs.c | 9 +++++++++ fs/proc/fd.c | 13 +++++++++++-- include/linux/fs.h | 1 + 4 files changed, 31 insertions(+), 2 deletions(-) diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 779c05528e87..ca23a9af4845 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -1907,6 +1907,9 @@ All locks associated with a file descriptor are shown in its fdinfo too:: lock: 1: FLOCK ADVISORY WRITE 359 00:13:11691 0 EOF +Files with anonymous inodes have an additional 'path' field which represents +the anonymous file path. + The files such as eventfd, fsnotify, signalfd, epoll among the regular pos/flags pair provide additional information particular to the objects they represent. @@ -1920,6 +1923,7 @@ Eventfd files mnt_id: 9 ino: 63107 size: 0 + path: anon_inode:[eventfd] eventfd-count: 5a where 'eventfd-count' is hex value of a counter. @@ -1934,6 +1938,7 @@ Signalfd files mnt_id: 9 ino: 63107 size: 0 + path: anon_inode:[signalfd] sigmask: 0000000000000200 where 'sigmask' is hex value of the signal mask associated @@ -1949,6 +1954,7 @@ Epoll files mnt_id: 9 ino: 63107 size: 0 + path: anon_inode:[eventpoll] tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7 where 'tfd' is a target file descriptor number in decimal form, @@ -1968,6 +1974,7 @@ For inotify files the format is the following:: mnt_id: 9 ino: 63107 size: 0 + path: anon_inode:inotify 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 @@ -1992,6 +1999,7 @@ For fanotify files the format is:: mnt_id: 9 ino: 63107 size: 0 + path: anon_inode:[fanotify] 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 @@ -2018,6 +2026,7 @@ Timerfd files mnt_id: 9 ino: 63107 size: 0 + path: anon_inode:[timerfd] clockid: 0 ticks: 0 settime flags: 01 @@ -2042,6 +2051,7 @@ DMA Buffer files mnt_id: 9 ino: 63107 size: 32768 + path: /dmabuf: count: 2 exp_name: system-heap diff --git a/fs/libfs.c b/fs/libfs.c index 31b0ddf01c31..6911749b4da7 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -1217,6 +1217,15 @@ void kfree_link(void *p) } EXPORT_SYMBOL(kfree_link); +static const struct address_space_operations anon_aops = { + .dirty_folio = noop_dirty_folio, +}; + +bool is_anon_inode(struct inode *inode) +{ + return inode->i_mapping->a_ops == &anon_aops; +} + struct inode *alloc_anon_inode(struct super_block *s) { static const struct address_space_operations anon_aops = { diff --git a/fs/proc/fd.c b/fs/proc/fd.c index 464bc3f55759..5bac79a2fa51 100644 --- a/fs/proc/fd.c +++ b/fs/proc/fd.c @@ -23,6 +23,7 @@ static int seq_show(struct seq_file *m, void *v) struct files_struct *files = NULL; int f_flags = 0, ret = -ENOENT; struct file *file = NULL; + struct inode *inode = NULL; struct task_struct *task; task = get_proc_task(m->private); @@ -54,11 +55,19 @@ static int seq_show(struct seq_file *m, void *v) if (ret) return ret; + inode = file_inode(file); + seq_printf(m, "pos:\t%lli\n", (long long)file->f_pos); seq_printf(m, "flags:\t0%o\n", f_flags); seq_printf(m, "mnt_id:\t%i\n", real_mount(file->f_path.mnt)->mnt_id); - seq_printf(m, "ino:\t%lu\n", file_inode(file)->i_ino); - seq_printf(m, "size:\t%lli\n", (long long)file_inode(file)->i_size); + seq_printf(m, "ino:\t%lu\n", inode->i_ino); + seq_printf(m, "size:\t%lli\n", (long long)inode->i_size); + + if (is_anon_inode(inode)) { + seq_puts(m, "path:\t"); + seq_file_path(m, file, "\n"); + seq_putc(m, '\n'); + } /* show_fd_locks() never deferences files so a stale value is safe */ show_fd_locks(m, file, files); diff --git a/include/linux/fs.h b/include/linux/fs.h index 9ad5e3520fae..73449e620b66 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3111,6 +3111,7 @@ extern void page_put_link(void *); extern int page_symlink(struct inode *inode, const char *symname, int len); extern const struct inode_operations page_symlink_inode_operations; extern void kfree_link(void *); +extern bool is_anon_inode(struct inode *inode); void generic_fillattr(struct user_namespace *, struct inode *, struct kstat *); void generic_fill_statx_attr(struct inode *inode, struct kstat *stat); extern int vfs_getattr_nosec(const struct path *, struct kstat *, u32, unsigned int);