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=-9.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 88EF6C43387 for ; Thu, 10 Jan 2019 17:05:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4C9F820685 for ; Thu, 10 Jan 2019 17:05:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="pi5WuoFd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729149AbfAJRFE (ORCPT ); Thu, 10 Jan 2019 12:05:04 -0500 Received: from mail-wr1-f65.google.com ([209.85.221.65]:45719 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728959AbfAJRFE (ORCPT ); Thu, 10 Jan 2019 12:05:04 -0500 Received: by mail-wr1-f65.google.com with SMTP id t6so12176453wrr.12 for ; Thu, 10 Jan 2019 09:05:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=41DgcMKK3EPUqCvO/Uvm5LS1fGai8LcgaD9746/8r60=; b=pi5WuoFdeehqYb4UWnXR3qRjPryZEGLnstJk2KfIKy6glTpmY4dHQJuNiH6NOfrOFn 3v16ButrxXilpACu81AcqfV1pdZzUp9dHhKdlYvabvD2j9XqIzWoGRc2SWoLULNC11Cs Oo2piVujKapkB8kFtYChhIj/pZV5Cwb15kXTaguESCr5HQ4JKffSOCBnPndNM0MaN7gd eSAqdHHfe/eaPRSFfLK0vtMXgxh23jWOKmxNe6DsQ+CVJCIARz9F+EtyKhuKUkphY73W +C+4mr6IeqPAGelq2Tli24wdAWTxst6wi1xX1+CJk1M7S90up2nI24nmgAEAShTg6PWS ot5Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=41DgcMKK3EPUqCvO/Uvm5LS1fGai8LcgaD9746/8r60=; b=Ml6jxkqcl9VJXvHgXheDQrEhh9+Qyb0AgWKIYxWAmYIdpKb/Z6NYrcIXyIbXYd8jB9 yZNkMC3uPf0uHjwh1Wn8QRy+REHuSgvHoEU/+0MVmymhp4+D1ISqhsQIejcLXtP0wERB abgVGuvPv1rhkk4J6zYuN5B9e/qrxbGGC0OcFNPMlK+nd7fv2MGHyCE62kNzuSEC/1D3 Jm1od3CTsbFllnNr2pISgOjLPe6zUpyEVzVkO2RhUE685W3Sxw8LigHbYrQ5/7zfYrPa fFg0wJAjlQ75n8401AH034EpZv6NL6+sX9ZNInhcEZtBvlcJkXeY7f1a3EJh8MhmeRUx QrPA== X-Gm-Message-State: AJcUuke95FF4W5zx3EjHRSvQBRhyZbukrFta7D0akUiPGI/UnZEPzfVF m/AUC+2/FeTQs6pvgv3Q4KV9/CGT X-Google-Smtp-Source: ALg8bN4/CJ2y6FkONLxbnND1w3wK/LjNdVcaNkmnmaDxrxa9wKVeeYeTgbYl7ovl4bflr9/uKiaX2w== X-Received: by 2002:adf:e6ce:: with SMTP id y14mr10477360wrm.239.1547139901040; Thu, 10 Jan 2019 09:05:01 -0800 (PST) Received: from amir-VirtualBox.ctera.local ([188.120.129.201]) by smtp.gmail.com with ESMTPSA id m4sm5725868wmi.3.2019.01.10.09.04.59 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 10 Jan 2019 09:05:00 -0800 (PST) From: Amir Goldstein To: Jan Kara Cc: Matthew Bobrowski , linux-fsdevel@vger.kernel.org Subject: [PATCH v5 07/17] fanotify: encode file identifier for FAN_REPORT_FID Date: Thu, 10 Jan 2019 19:04:34 +0200 Message-Id: <20190110170444.30616-8-amir73il@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190110170444.30616-1-amir73il@gmail.com> References: <20190110170444.30616-1-amir73il@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org When user requests the flag FAN_REPORT_FID in fanotify_init(), a unique file identifier of the event target object will be reported with the event. The file identifier includes the filesystem's fsid (i.e. from statfs(2)) and an NFS file handle of the file (i.e. from name_to_handle_at(2)). The file identifier makes holding the path reference and passing a file descriptor to user redundant, so those are disabled in a group with FAN_REPORT_FID. Encode fid and store it in event for a group with FAN_REPORT_FID. Up to 12 bytes of file handle on 32bit arch (16 bytes on 64bit arch) are stored inline in fanotify_event struct. Larger file handles are stored in an external allocated buffer. On failure to encode fid, we print a warning and queue the event without the fid information. Signed-off-by: Amir Goldstein --- fs/notify/fanotify/fanotify.c | 81 +++++++++++++++++++++++++++--- fs/notify/fanotify/fanotify.h | 78 ++++++++++++++++++++++++++-- fs/notify/fanotify/fanotify_user.c | 6 +-- include/uapi/linux/fanotify.h | 1 + 4 files changed, 153 insertions(+), 13 deletions(-) diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c index d8e3b6e50844..e431f63c9f58 100644 --- a/fs/notify/fanotify/fanotify.c +++ b/fs/notify/fanotify/fanotify.c @@ -13,6 +13,7 @@ #include #include #include +#include #include "fanotify.h" @@ -25,10 +26,18 @@ static bool should_merge(struct fsnotify_event *old_fsn, old = FANOTIFY_E(old_fsn); new = FANOTIFY_E(new_fsn); - if (old_fsn->inode == new_fsn->inode && old->pid == new->pid && - old->path.mnt == new->path.mnt && - old->path.dentry == new->path.dentry) - return true; + if (old_fsn->inode != new_fsn->inode || old->pid != new->pid || + old->fh_type != new->fh_type || old->fh_len != new->fh_len) + return false; + + if (fanotify_event_has_path(old)) { + return old->path.mnt == new->path.mnt && + old->path.dentry == new->path.dentry; + } else if (fanotify_event_has_fid(old)) { + return fanotify_fid_equal(&old->fid, &new->fid, old->fh_len); + } + + /* Do not merge events if we failed to encode fid */ return false; } @@ -143,6 +152,57 @@ static u32 fanotify_group_event_mask(struct fsnotify_iter_info *iter_info, ~marks_ignored_mask; } +static int fanotify_encode_fid(struct fanotify_event *event, + const struct path *path, gfp_t gfp) +{ + struct fanotify_fid *fid = &event->fid; + int dwords, bytes = 0; + struct kstatfs stat; + int err, type; + + stat.f_fsid.val[0] = stat.f_fsid.val[1] = 0; + fid->ext_fh = NULL; + dwords = 0; + err = -ENOENT; + type = exportfs_encode_fh(path->dentry, NULL, &dwords, 0); + if (!dwords) + goto out_err; + + err = vfs_statfs(path, &stat); + if (err) + goto out_err; + + bytes = dwords << 2; + if (bytes > FANOTIFY_INLINE_FH_LEN) { + /* Treat failure to allocate fh as failure to allocate event */ + err = -ENOMEM; + fid->ext_fh = kmalloc(bytes, gfp); + if (!fid->ext_fh) + goto out_err; + } + + type = exportfs_encode_fh(path->dentry, fanotify_fid_fh(fid, bytes), + &dwords, 0); + err = -EINVAL; + if (!type || type == FILEID_INVALID || bytes != dwords << 2) + goto out_err; + + fid->fsid = stat.f_fsid; + event->fh_len = bytes; + + return type; + +out_err: + pr_warn_ratelimited("fanotify: failed to encode fid (fsid=%x.%x, type=%d, bytes=%d, err=%i)\n", + stat.f_fsid.val[0], stat.f_fsid.val[1], + type, bytes, err); + kfree(fid->ext_fh); + fid->ext_fh = NULL; + event->fh_len = 0; + + return FILEID_INVALID; +} + struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group, struct inode *inode, u32 mask, const struct path *path) @@ -181,10 +241,16 @@ init: __maybe_unused event->pid = get_pid(task_pid(current)); else event->pid = get_pid(task_tgid(current)); - if (path) { + event->fh_len = 0; + if (path && FAN_GROUP_FLAG(group, FAN_REPORT_FID)) { + /* Report the event without a file identifier on encode error */ + event->fh_type = fanotify_encode_fid(event, path, gfp); + } else if (path) { + event->fh_type = FILEID_ROOT; event->path = *path; path_get(&event->path); } else { + event->fh_type = FILEID_INVALID; event->path.mnt = NULL; event->path.dentry = NULL; } @@ -281,7 +347,10 @@ static void fanotify_free_event(struct fsnotify_event *fsn_event) struct fanotify_event *event; event = FANOTIFY_E(fsn_event); - path_put(&event->path); + if (fanotify_event_has_path(event)) + path_put(&event->path); + else if (fanotify_event_has_ext_fh(event)) + kfree(event->fid.ext_fh); put_pid(event->pid); if (fanotify_is_perm_event(event->mask)) { kmem_cache_free(fanotify_perm_event_cachep, diff --git a/fs/notify/fanotify/fanotify.h b/fs/notify/fanotify/fanotify.h index 898b5b2bc1c7..271482fb9611 100644 --- a/fs/notify/fanotify/fanotify.h +++ b/fs/notify/fanotify/fanotify.h @@ -2,11 +2,49 @@ #include #include #include +#include extern struct kmem_cache *fanotify_mark_cache; extern struct kmem_cache *fanotify_event_cachep; extern struct kmem_cache *fanotify_perm_event_cachep; +/* + * 3 dwords are sufficient for most local fs (64bit ino, 32bit generation). + * For 32bit arch, fid increases the size of fanotify_event by 12 bytes and + * fh_* fields increase the size of fanotify_event by another 4 bytes. + * For 64bit arch, fid increases the size of fanotify_fid by 8 bytes and + * fh_* fields are packed in a hole after mask. + */ +#if BITS_PER_LONG == 32 +#define FANOTIFY_INLINE_FH_LEN (3 << 2) +#else +#define FANOTIFY_INLINE_FH_LEN (4 << 2) +#endif + +struct fanotify_fid { + __kernel_fsid_t fsid; + union { + unsigned char fh[FANOTIFY_INLINE_FH_LEN]; + unsigned char *ext_fh; + }; +}; + +static inline void *fanotify_fid_fh(struct fanotify_fid *fid, + unsigned int fh_len) +{ + return fh_len <= FANOTIFY_INLINE_FH_LEN ? fid->fh : fid->ext_fh; +} + +static inline bool fanotify_fid_equal(struct fanotify_fid *fid1, + struct fanotify_fid *fid2, + unsigned int fh_len) +{ + return fid1->fsid.val[0] == fid2->fsid.val[0] && + fid1->fsid.val[1] == fid2->fsid.val[1] && + !memcmp(fanotify_fid_fh(fid1, fh_len), + fanotify_fid_fh(fid2, fh_len), fh_len); +} + /* * Structure for normal fanotify events. It gets allocated in * fanotify_handle_event() and freed when the information is retrieved by @@ -16,13 +54,47 @@ struct fanotify_event { struct fsnotify_event fse; u32 mask; /* - * We hold ref to this path so it may be dereferenced at any point - * during this object's lifetime + * Those fields are outside fanotify_fid to pack fanotify_event nicely + * on 64bit arch and to use fh_type as an indication of whether path + * or fid are used in the union: + * FILEID_ROOT (0) for path, > 0 for fid, FILEID_INVALID for neither. */ - struct path path; + u8 fh_type; + u8 fh_len; + u16 pad; + union { + /* + * We hold ref to this path so it may be dereferenced at any + * point during this object's lifetime + */ + struct path path; + /* + * With FAN_REPORT_FID, we do not hold any reference on the + * victim object. Instead we store its NFS file handle and its + * filesystem's fsid as a unique identifier. + */ + struct fanotify_fid fid; + }; struct pid *pid; }; +static inline bool fanotify_event_has_path(struct fanotify_event *event) +{ + return event->fh_type == FILEID_ROOT; +} + +static inline bool fanotify_event_has_fid(struct fanotify_event *event) +{ + return event->fh_type != FILEID_ROOT && + event->fh_type != FILEID_INVALID; +} + +static inline bool fanotify_event_has_ext_fh(struct fanotify_event *event) +{ + return fanotify_event_has_fid(event) && + event->fh_len > FANOTIFY_INLINE_FH_LEN; +} + /* * Structure for permission fanotify events. It gets allocated and freed in * fanotify_handle_event() since we wait there for user response. When the diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index 2f4901ac090c..68a1cb18ddd8 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -181,7 +181,7 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, struct fanotify_event_metadata metadata; struct fanotify_event *event; struct file *f; - int fd, ret; + int ret, fd = FAN_NOFD; pr_debug("%s: group=%p event=%p\n", __func__, group, fsn_event); @@ -193,9 +193,7 @@ static ssize_t copy_event_to_user(struct fsnotify_group *group, metadata.mask = event->mask & FANOTIFY_OUTGOING_EVENTS; metadata.pid = pid_vnr(event->pid); - if (unlikely(event->mask & FAN_Q_OVERFLOW)) { - fd = FAN_NOFD; - } else { + if (fanotify_event_has_path(event)) { fd = create_fd(group, event, &f); if (fd < 0) return fd; diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h index 909c98fcace2..d07f3cbc2786 100644 --- a/include/uapi/linux/fanotify.h +++ b/include/uapi/linux/fanotify.h @@ -44,6 +44,7 @@ /* Flags to determine fanotify event format */ #define FAN_REPORT_TID 0x00000100 /* event->pid is thread id */ +#define FAN_REPORT_FID 0x00000200 /* Report unique file id */ /* Deprecated - do not use this in programs and do not add new flags here! */ #define FAN_ALL_INIT_FLAGS (FAN_CLOEXEC | FAN_NONBLOCK | \ -- 2.17.1