From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-f66.google.com ([209.85.221.66]:36232 "EHLO mail-wr1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726312AbeKZAf1 (ORCPT ); Sun, 25 Nov 2018 19:35:27 -0500 From: Amir Goldstein To: Jan Kara Cc: Matthew Bobrowski , linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org Subject: [PATCH v3 08/13] fanotify: enable FAN_REPORT_FID init flag Date: Sun, 25 Nov 2018 15:43:47 +0200 Message-Id: <20181125134352.21499-9-amir73il@gmail.com> In-Reply-To: <20181125134352.21499-1-amir73il@gmail.com> References: <20181125134352.21499-1-amir73il@gmail.com> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: When setting up an fanotify listener, user may request to get fid information in event instead of an open file descriptor. The fid obtained with event on a watched object contains the file handle returned by name_to_handle_at(2) and fsid returned by statfs(2). When setting a mark, we need to make sure that the filesystem supports encoding file handles with name_to_handle_at(2) and that statfs(2) encodes a non-zero fsid. Cc: Signed-off-by: Amir Goldstein --- fs/notify/fanotify/fanotify_user.c | 54 +++++++++++++++++++++++++++++- fs/statfs.c | 4 ++- include/linux/fanotify.h | 2 +- include/linux/statfs.h | 3 ++ 4 files changed, 60 insertions(+), 3 deletions(-) diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index ea8e81a3e80b..d7aa2f392a64 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -17,6 +17,8 @@ #include #include #include +#include +#include #include @@ -857,6 +859,49 @@ SYSCALL_DEFINE2(fanotify_init, unsigned int, flags, unsigned int, event_f_flags) return fd; } +/* Check if filesystem can encode a unique fid */ +static int fanotify_test_fid(struct path *path) +{ + struct kstatfs stat, root_stat; + int err; + + /* + * Make sure path is not in filesystem with zero fsid (e.g. tmpfs). + * TODO: cache fsid in the mark connector. + */ + err = vfs_statfs(path, &stat); + if (err) + return err; + + if (!stat.f_fsid.val[0] && !stat.f_fsid.val[1]) + return -ENODEV; + + /* + * Make sure path is not inside a filesystem subvolume (e.g. btrfs) + * which uses a different fsid than sb root. + */ + err = statfs_by_dentry(path->dentry->d_sb->s_root, &root_stat); + if (err) + return err; + + if (root_stat.f_fsid.val[0] != stat.f_fsid.val[0] || + root_stat.f_fsid.val[1] != stat.f_fsid.val[1]) + return -EXDEV; + + /* + * We need to make sure that the file system supports at least + * encoding a file handle so user can use name_to_handle_at() to + * compare fid returned with event to the file handle of watched + * objects. However, name_to_handle_at() requires that the + * filesystem also supports decoding file handles. + */ + if (!path->dentry->d_sb->s_export_op || + !path->dentry->d_sb->s_export_op->fh_to_dentry) + return -EOPNOTSUPP; + + return 0; +} + static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, int dfd, const char __user *pathname) { @@ -942,6 +987,12 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, if (ret) goto fput_and_out; + if (FAN_GROUP_FLAG(group, FAN_REPORT_FID)) { + ret = fanotify_test_fid(&path); + if (ret) + goto path_put_and_out; + } + /* inode held in place by reference to path; group by fget on fd */ if (mark_type == FAN_MARK_INODE) inode = path.dentry->d_inode; @@ -970,6 +1021,7 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, ret = -EINVAL; } +path_put_and_out: path_put(&path); fput_and_out: fdput(f); @@ -1006,7 +1058,7 @@ COMPAT_SYSCALL_DEFINE6(fanotify_mark, */ static int __init fanotify_user_setup(void) { - BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 7); + BUILD_BUG_ON(HWEIGHT32(FANOTIFY_INIT_FLAGS) != 8); BUILD_BUG_ON(HWEIGHT32(FANOTIFY_MARK_FLAGS) != 9); fanotify_mark_cache = KMEM_CACHE(fsnotify_mark, diff --git a/fs/statfs.c b/fs/statfs.c index f0216629621d..6a5d840a2d8d 100644 --- a/fs/statfs.c +++ b/fs/statfs.c @@ -50,7 +50,8 @@ static int calculate_f_flags(struct vfsmount *mnt) flags_by_sb(mnt->mnt_sb->s_flags); } -static int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf) +/* Does not set buf->f_flags */ +int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf) { int retval; @@ -66,6 +67,7 @@ static int statfs_by_dentry(struct dentry *dentry, struct kstatfs *buf) buf->f_frsize = buf->f_bsize; return retval; } +EXPORT_SYMBOL(statfs_by_dentry); int vfs_statfs(const struct path *path, struct kstatfs *buf) { diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h index 9e2142795335..f59be967f72b 100644 --- a/include/linux/fanotify.h +++ b/include/linux/fanotify.h @@ -19,7 +19,7 @@ FAN_CLASS_PRE_CONTENT) #define FANOTIFY_INIT_FLAGS (FANOTIFY_CLASS_BITS | \ - FAN_REPORT_TID | \ + FAN_REPORT_TID | FAN_REPORT_FID | \ FAN_CLOEXEC | FAN_NONBLOCK | \ FAN_UNLIMITED_QUEUE | FAN_UNLIMITED_MARKS) diff --git a/include/linux/statfs.h b/include/linux/statfs.h index 3142e98546ac..2c3ca7cb8c98 100644 --- a/include/linux/statfs.h +++ b/include/linux/statfs.h @@ -41,4 +41,7 @@ struct kstatfs { #define ST_NODIRATIME 0x0800 /* do not update directory access times */ #define ST_RELATIME 0x1000 /* update atime relative to mtime/ctime */ +struct dentry; +extern int statfs_by_dentry(struct dentry *dentry, struct kstatfs *stat); + #endif -- 2.17.1