From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx3-rdu2.redhat.com ([66.187.233.73]:59548 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965181AbeEYAFZ (ORCPT ); Thu, 24 May 2018 20:05:25 -0400 Subject: [PATCH 00/32] VFS: Introduce filesystem context [ver #8] From: David Howells To: viro@zeniv.linux.org.uk Cc: dhowells@redhat.com, linux-fsdevel@vger.kernel.org, linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org Date: Fri, 25 May 2018 01:05:23 +0100 Message-ID: <152720672288.9073.9868393448836301272.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Hi Al, Can you take a look at this please, in particular the last 6 patches? Here are a set of patches to create a filesystem context prior to setting up a new mount, populating it with the parsed options/binary data, creating the superblock and then effecting the mount. This is also used for remount since much of the parsing stuff is common in many filesystems. This allows namespaces and other information to be conveyed through the mount procedure. This also allows Miklós Szeredi's idea of doing: fd = fsopen("nfs"); write(fd, "option=val", ...); mfd = fsmount(fd, MS_NODEV); move_mount(mfd, "", AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH); that he presented at LSF-2017 to be implemented (see the relevant patches in the series). I didn't use netlink as that would make the core kernel depend on CONFIG_NET and CONFIG_NETLINK and would introduce network namespacing issues. I've implemented filesystem context handling for procfs, nfs, mqueue, cpuset, kernfs, sysfs, cgroup and afs filesystems. Unconverted filesystems are handled by the legacy filesystem wrapper. This post is mostly about the internal filesystem context and the special kernel interface filesystems. I've included the fsopen() and fsmount() syscall implementations for reference, but I expect these to undergo some reconsideration during LSF. The last five patches relate to the AFS conversion and are included as an example. Significant changes: ver #8: (*) Changed the way fsmount() mounts into the namespace according to some of Al's ideas. (*) Put better typing on the fd cookie obtained from __fdget() & co.. (*) Stored the fd cookie in struct nameidata rather than the dfd number. (*) Changed sys_fsmount() to return an O_PATH-style fd rather than actually mounting into the mount namespace. (*) Separated internal FMODE_* handling from O_* handling to free up certain O_* flag numbers. (*) Added two new open flags (O_CLONE_MOUNT and O_NON_RECURSIVE) for use with open(O_PATH) to copy a mount or mount-subtree to an O_PATH fd. (*) Added a new syscall, sys_move_mount(), to move a mount from an dfd+path source to a dfd+path destination. (*) Added a file->f_mode flag (FMODE_NEED_UNMOUNT) that indicates that the vfsmount attached to file->f_path needs 'unmounting' if set. (*) Made sys_move_mount() clear FMODE_NEED_UNMOUNT if successful. [!] This doesn't work quite right. (*) Added a new syscall, fsinfo(), to query information about a filesystem. The idea being that this will, in future, work with the fd from fsopen() too and permit querying of the parameters and metadata before fsmount() is called. ver #7: (*) Undo an incorrect MS_* -> SB_* conversion. (*) Pass the mount data buffer size to all the mount-related functions that take the data pointer. This fixes a problem where someone (say SELinux) tries to copy the mount data, assuming it to be a page in size, and overruns the buffer - thereby incurring an oops by hitting a guard page. (*) Made the AFS filesystem use them as an example. This is a much easier to deal with than with NFS or Ext4 as there are very few mount options. ver #6: (*) Dropped the supplementary error string facility for the moment. (*) Dropped the NFS patches for the moment. (*) Dropped the reserved file descriptor argument from fsopen() and replaced it with three reserved pointers that must be NULL. ver #5: (*) Renamed sb_config -> fs_context and adjusted variable names. (*) Differentiated the flags in sb->s_flags (now named SB_*) from those passed to mount(2) (named MS_*). (*) Renamed __vfs_new_fs_context() to vfs_new_fs_context() and made the caller always provide a struct file_system_type pointer and the parameters required. (*) Got rid of vfs_submount_fc() in favour of passing FS_CONTEXT_FOR_SUBMOUNT to vfs_new_fs_context(). The purpose is now used more. (*) Call ->validate() on the remount path. (*) Got rid of the inode locking in sys_fsmount(). (*) Call security_sb_mountpoint() in the mount(2) path. ver #4: (*) Split the sb_config patch up somewhat. (*) Made the supplementary error string facility something attached to the task_struct rather than the sb_config so that error messages can be obtained from NFS doing a mount-root-and-pathwalk inside the nfs_get_tree() operation. Further, made this managed and read by prctl rather than through the mount fd so that it's more generally available. ver #3: (*) Rebased on 4.12-rc1. (*) Split the NFS patch up somewhat. ver #2: (*) Removed the ->fill_super() from sb_config_operations and passed it in directly to functions that want to call it. NFS now calls nfs_fill_super() directly rather than jumping through a pointer to it since there's only the one option at the moment. (*) Removed ->mnt_ns and ->sb from sb_config and moved ->pid_ns into proc_sb_config. (*) Renamed create_super -> get_tree. (*) Renamed struct mount_context to struct sb_config and amended various variable names. (*) sys_fsmount() acquired AT_* flags and MS_* flags (for MNT_* flags) arguments. ver #1: (*) Split the sb_config stuff out into its own header. (*) Support non-context aware filesystems through a special set of sb_config operations. (*) Stored the created superblock and root dentry into the sb_config after creation rather than directly into a vfsmount. This allows some arguments to be removed to various NFS functions. (*) Added an explicit superblock-creation step. This allows a created superblock to then be mounted multiple times. (*) Added a flag to say that the sb_config is degraded and cannot have another go at having a superblock creation whilst getting rid of the one that says it's already mounted. Possible further developments: (*) Implement sb reconfiguration (for now it returns ENOANO). (*) Implement mount context support in more filesystems, ext4 being next on my list. (*) Move the walk-from-root stuff that nfs has to generic code so that you can do something akin to: mount /dev/sda1:/foo/bar /mnt See nfs_follow_remote_path() and mount_subtree(). This is slightly tricky in NFS as we have to prevent referral loops. (*) Work out how to get at the error message incurred by submounts encountered during nfs_follow_remote_path(). Should the error message be moved to task_struct and made more general, perhaps retrieved with a prctl() function? (*) Clean up/consolidate the security functions. Possibly add a validation hook to be called at the same time as the mount context validate op. The patches can be found here also: http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=mount-context David --- David Howells (32): VFS: Suppress MS_* flag defs within the kernel unless explicitly enabled vfs: Provide documentation for new mount API VFS: Introduce the basic header for the new mount API's filesystem context VFS: Add LSM hooks for the new mount API selinux: Implement the new mount API LSM hooks smack: Implement filesystem context security hooks apparmor: Implement security hooks for the new mount API tomoyo: Implement security hooks for the new mount API VFS: Require specification of size of mount data for internal mounts VFS: Implement a filesystem superblock creation/configuration context VFS: Remove unused code after filesystem context changes procfs: Move proc_fill_super() to fs/proc/root.c proc: Add fs_context support to procfs ipc: Convert mqueue fs to fs_context cpuset: Use fs_context kernfs, sysfs, cgroup, intel_rdt: Support fs_context hugetlbfs: Convert to fs_context VFS: Remove kern_mount_data() VFS: Implement fsopen() to prepare for a mount vfs: Make close() unmount the attached mount if so flagged VFS: Implement fsmount() to effect a pre-configured mount vfs: Provide an fspick() system call VFS: Implement logging through fs_context vfs: Add some logging to the core users of the fs_context log afs: Add fs_context support afs: Use fs_context to pass parameters over automount vfs: Use a 'struct fd_cookie *' type for light fd handling vfs: Store the fd_cookie in nameidata, not the dfd int vfs: Don't mix FMODE_* flags with O_* flags vfs: Allow cloning of a mount tree with open(O_PATH|O_CLONE_MOUNT) [RFC] fs: Add a move_mount() system call [RFC] fsinfo: Add a system call to allow querying of filesystem information Documentation/filesystems/mounting.txt | 458 +++++++++++++ arch/arc/kernel/setup.c | 1 arch/arm/kernel/atags_parse.c | 1 arch/ia64/kernel/perfmon.c | 3 arch/powerpc/platforms/cell/spufs/inode.c | 6 arch/s390/hypfs/inode.c | 7 arch/sh/kernel/setup.c | 1 arch/sparc/kernel/setup_32.c | 1 arch/sparc/kernel/setup_64.c | 1 arch/x86/entry/syscalls/syscall_32.tbl | 5 arch/x86/entry/syscalls/syscall_64.tbl | 5 arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 129 ++-- arch/x86/kernel/setup.c | 1 drivers/base/devtmpfs.c | 7 drivers/dax/super.c | 2 drivers/dma-buf/dma-buf.c | 2 drivers/dma-buf/sync_file.c | 2 drivers/gpu/drm/drm_drv.c | 3 drivers/gpu/drm/drm_syncobj.c | 2 drivers/gpu/drm/i915/i915_gemfs.c | 2 drivers/infiniband/hw/qib/qib_fs.c | 7 drivers/misc/ibmasm/ibmasmfs.c | 11 drivers/mtd/mtdsuper.c | 26 - drivers/oprofile/oprofilefs.c | 8 .../staging/lustre/lustre/llite/llite_internal.h | 2 drivers/staging/lustre/lustre/llite/llite_lib.c | 3 drivers/staging/lustre/lustre/mdc/mdc_lib.c | 2 drivers/staging/lustre/lustre/mdc/mdc_locks.c | 2 drivers/staging/lustre/lustre/obdclass/obd_mount.c | 7 drivers/staging/ncpfs/inode.c | 10 drivers/tty/pty.c | 4 drivers/usb/gadget/function/f_fs.c | 7 drivers/usb/gadget/legacy/inode.c | 7 drivers/virtio/virtio_balloon.c | 2 drivers/xen/xenfs/super.c | 7 fs/9p/vfs_super.c | 2 fs/Makefile | 3 fs/adfs/super.c | 9 fs/affs/super.c | 13 fs/afs/internal.h | 9 fs/afs/mntpt.c | 147 ++-- fs/afs/super.c | 423 ++++++------ fs/afs/volume.c | 4 fs/aio.c | 3 fs/anon_inodes.c | 23 - fs/autofs4/autofs_i.h | 2 fs/autofs4/dev-ioctl.c | 2 fs/autofs4/init.c | 4 fs/autofs4/inode.c | 3 fs/befs/linuxvfs.c | 11 fs/bfs/inode.c | 8 fs/binfmt_misc.c | 7 fs/block_dev.c | 2 fs/btrfs/super.c | 30 + fs/btrfs/tests/btrfs-tests.c | 2 fs/cachefiles/rdwr.c | 2 fs/ceph/super.c | 3 fs/cifs/cifs_dfs_ref.c | 3 fs/cifs/cifsfs.c | 5 fs/coda/inode.c | 11 fs/configfs/mount.c | 7 fs/cramfs/inode.c | 17 fs/debugfs/inode.c | 14 fs/devpts/inode.c | 10 fs/ecryptfs/main.c | 2 fs/efivarfs/super.c | 9 fs/efs/super.c | 14 fs/eventfd.c | 2 fs/eventpoll.c | 2 fs/exec.c | 6 fs/exofs/super.c | 7 fs/exportfs/expfs.c | 2 fs/ext2/super.c | 14 fs/ext4/super.c | 16 fs/f2fs/super.c | 13 fs/fat/inode.c | 3 fs/fat/namei_msdos.c | 8 fs/fat/namei_vfat.c | 8 fs/fcntl.c | 6 fs/file.c | 20 - fs/file_table.c | 4 fs/freevxfs/vxfs_super.c | 12 fs/fs_context.c | 689 ++++++++++++++++++++ fs/fsopen.c | 477 ++++++++++++++ fs/fuse/control.c | 9 fs/fuse/inode.c | 16 fs/gfs2/ops_fstype.c | 6 fs/gfs2/super.c | 4 fs/hfs/super.c | 12 fs/hfsplus/super.c | 12 fs/hostfs/hostfs_kern.c | 7 fs/hpfs/super.c | 11 fs/hugetlbfs/inode.c | 337 ++++++---- fs/internal.h | 10 fs/isofs/inode.c | 11 fs/jffs2/super.c | 10 fs/jfs/super.c | 11 fs/kernfs/mount.c | 88 +-- fs/libfs.c | 17 fs/minix/inode.c | 14 fs/namei.c | 105 ++- fs/namespace.c | 650 +++++++++++++++---- fs/nfs/dir.c | 15 fs/nfs/internal.h | 4 fs/nfs/namespace.c | 3 fs/nfs/nfs4namespace.c | 3 fs/nfs/nfs4proc.c | 9 fs/nfs/nfs4super.c | 27 - fs/nfs/super.c | 22 - fs/nfsd/nfsctl.c | 8 fs/nilfs2/super.c | 10 fs/notify/fanotify/fanotify_user.c | 10 fs/notify/inotify/inotify_user.c | 2 fs/nsfs.c | 5 fs/ntfs/super.c | 13 fs/ocfs2/dlmfs/dlmfs.c | 5 fs/ocfs2/super.c | 14 fs/omfs/inode.c | 9 fs/open.c | 31 + fs/openpromfs/inode.c | 11 fs/orangefs/orangefs-kernel.h | 2 fs/orangefs/super.c | 5 fs/overlayfs/super.c | 11 fs/pipe.c | 3 fs/pnode.c | 1 fs/proc/inode.c | 50 - fs/proc/internal.h | 6 fs/proc/root.c | 212 +++++- fs/pstore/inode.c | 10 fs/qnx4/inode.c | 14 fs/qnx6/inode.c | 14 fs/ramfs/inode.c | 6 fs/reiserfs/super.c | 14 fs/romfs/super.c | 13 fs/signalfd.c | 3 fs/squashfs/super.c | 12 fs/statfs.c | 431 +++++++++++++ fs/super.c | 402 +++++++++--- fs/sysfs/mount.c | 64 +- fs/sysv/inode.c | 3 fs/sysv/super.c | 16 fs/timerfd.c | 2 fs/tracefs/inode.c | 10 fs/ubifs/super.c | 5 fs/udf/super.c | 16 fs/ufs/super.c | 11 fs/xfs/xfs_ioctl.c | 2 fs/xfs/xfs_super.c | 10 include/linux/anon_inodes.h | 6 include/linux/cgroup.h | 3 include/linux/debugfs.h | 8 include/linux/fcntl.h | 3 include/linux/file.h | 31 + include/linux/fs.h | 73 +- include/linux/fs_context.h | 178 +++++ include/linux/fsinfo.h | 25 + include/linux/fsnotify.h | 8 include/linux/kernfs.h | 36 + include/linux/lsm_hooks.h | 89 ++- include/linux/mount.h | 8 include/linux/mtd/super.h | 4 include/linux/nfs_fs.h | 3 include/linux/ramfs.h | 4 include/linux/security.h | 74 ++ include/linux/shmem_fs.h | 3 include/linux/syscalls.h | 11 include/uapi/asm-generic/fcntl.h | 9 include/uapi/linux/fs.h | 68 -- include/uapi/linux/fsinfo.h | 231 +++++++ include/uapi/linux/magic.h | 1 include/uapi/linux/mount.h | 69 ++ init/do_mounts.c | 5 init/do_mounts_initrd.c | 1 ipc/mqueue.c | 126 +++- kernel/bpf/inode.c | 7 kernel/bpf/syscall.c | 6 kernel/cgroup/cgroup-internal.h | 42 + kernel/cgroup/cgroup-v1.c | 296 ++++----- kernel/cgroup/cgroup.c | 224 ++++--- kernel/cgroup/cpuset.c | 65 ++ kernel/events/core.c | 2 kernel/sys_ni.c | 6 kernel/trace/trace.c | 7 mm/shmem.c | 10 mm/zsmalloc.c | 3 net/socket.c | 3 net/sunrpc/rpc_pipe.c | 7 net/unix/af_unix.c | 2 samples/statx/Makefile | 5 samples/statx/test-fsinfo.c | 179 +++++ security/apparmor/apparmorfs.c | 8 security/apparmor/file.c | 2 security/apparmor/include/mount.h | 11 security/apparmor/lsm.c | 84 ++ security/apparmor/mount.c | 47 + security/inode.c | 7 security/keys/big_key.c | 2 security/security.c | 70 ++ security/selinux/hooks.c | 294 ++++++++- security/selinux/selinuxfs.c | 8 security/smack/smack_lsm.c | 344 +++++++++- security/smack/smackfs.c | 9 security/tomoyo/common.h | 3 security/tomoyo/mount.c | 46 + security/tomoyo/tomoyo.c | 19 + 205 files changed, 6775 insertions(+), 1836 deletions(-) create mode 100644 Documentation/filesystems/mounting.txt create mode 100644 fs/fs_context.c create mode 100644 fs/fsopen.c create mode 100644 include/linux/fs_context.h create mode 100644 include/linux/fsinfo.h create mode 100644 include/uapi/linux/fsinfo.h create mode 100644 include/uapi/linux/mount.h create mode 100644 samples/statx/test-fsinfo.c