kernel.git/fs/overlayfs, branch linux-5.12.y

ovl: invalidate readdir cache on changes to dir with origin

2021-05-14T08:52:54Z

[ Upstream commit 65cd913ec9d9d71529665924c81015b7ab7d9381 ] The test in ovl_dentry_version_inc() was out-dated and did not include the case where readdir cache is used on a non-merge dir that has origin xattr, indicating that it may contain leftover whiteouts. To make the code more robust, use the same helper ovl_dir_is_real() to determine if readdir cache should be used and if readdir cache should be invalidated. Fixes: b79e05aaa166 ("ovl: no direct iteration for dir with origin xattr") Link: https://lore.kernel.org/linux-unionfs/CAOQ4uxht70nODhNHNwGFMSqDyOKLXOKrY0H6g849os4BQ7cokA@mail.gmail.com/ Cc: Chris Murphy Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin

ovl: show "userxattr" in the mount data

2021-05-14T08:52:54Z

[ Upstream commit 321b46b904816241044e177c1d6282ad20f17416 ] This was missed when adding the option. Signed-off-by: Giuseppe Scrivano Reviewed-by: Vivek Goyal Fixes: 2d2f2d7322ff ("ovl: user xattr") Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin

ovl: fix missing revert_creds() on error path

2021-05-14T08:52:13Z

commit 7b279bbfd2b230c7a210ff8f405799c7e46bbf48 upstream. Smatch complains about missing that the ovl_override_creds() doesn't have a matching revert_creds() if the dentry is disconnected. Fix this by moving the ovl_override_creds() until after the disconnected check. Fixes: aa3ff3c152ff ("ovl: copy up of disconnected dentries") Signed-off-by: Dan Carpenter Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: allow upperdir inside lowerdir

2021-05-07T10:53:25Z

commit 708fa01597fa002599756bf56a96d0de1677375c upstream. Commit 146d62e5a586 ("ovl: detect overlapping layers") made sure we don't have overlapping layers, but it also broke the arguably valid use case of mount -olowerdir=/,upperdir=/subdir,.. where upperdir overlaps lowerdir on the same filesystem. This has been causing regressions. Revert the check, but only for the specific case where upperdir and/or workdir are subdirectories of lowerdir. Any other overlap (e.g. lowerdir is subdirectory of upperdir, etc) case is crazy, so leave the check in place for those. Overlaps are detected at lookup time too, so reverting the mount time check should be safe. Fixes: 146d62e5a586 ("ovl: detect overlapping layers") Cc: # v5.2 Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: fix leaked dentry

2021-05-07T10:53:25Z

commit eaab1d45cdb4bb0c846bd23c3d666d5b90af7b41 upstream. Since commit 6815f479ca90 ("ovl: use only uppermetacopy state in ovl_lookup()"), overlayfs doesn't put temporary dentry when there is a metacopy error, which leads to dentry leaks when shutting down the related superblock: overlayfs: refusing to follow metacopy origin for (/file0) ... BUG: Dentry (____ptrval____){i=3f33,n=file3} still in use (1) [unmount of overlay overlay] ... WARNING: CPU: 1 PID: 432 at umount_check.cold+0x107/0x14d CPU: 1 PID: 432 Comm: unmount-overlay Not tainted 5.12.0-rc5 #1 ... RIP: 0010:umount_check.cold+0x107/0x14d ... Call Trace: d_walk+0x28c/0x950 ? dentry_lru_isolate+0x2b0/0x2b0 ? __kasan_slab_free+0x12/0x20 do_one_tree+0x33/0x60 shrink_dcache_for_umount+0x78/0x1d0 generic_shutdown_super+0x70/0x440 kill_anon_super+0x3e/0x70 deactivate_locked_super+0xc4/0x160 deactivate_super+0xfa/0x140 cleanup_mnt+0x22e/0x370 __cleanup_mnt+0x1a/0x30 task_work_run+0x139/0x210 do_exit+0xb0c/0x2820 ? __kasan_check_read+0x1d/0x30 ? find_held_lock+0x35/0x160 ? lock_release+0x1b6/0x660 ? mm_update_next_owner+0xa20/0xa20 ? reacquire_held_locks+0x3f0/0x3f0 ? __sanitizer_cov_trace_const_cmp4+0x22/0x30 do_group_exit+0x135/0x380 __do_sys_exit_group.isra.0+0x20/0x20 __x64_sys_exit_group+0x3c/0x50 do_syscall_64+0x45/0x70 entry_SYSCALL_64_after_hwframe+0x44/0xae ... VFS: Busy inodes after unmount of overlay. Self-destruct in 5 seconds. Have a nice day... This fix has been tested with a syzkaller reproducer. Cc: Amir Goldstein Cc: # v5.8+ Reported-by: syzbot Fixes: 6815f479ca90 ("ovl: use only uppermetacopy state in ovl_lookup()") Signed-off-by: Mickaël Salaün Link: https://lore.kernel.org/r/20210329164907.2133175-1-mic@digikod.net Reviewed-by: Vivek Goyal Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: fix reference counting in ovl_mmap error path

2021-04-23T21:42:39Z

mmap_region() now calls fput() on the vma->vm_file. Fix this by using vma_set_file() so it doesn't need to be handled manually here any more. Link: https://lkml.kernel.org/r/20210421132012.82354-2-christian.koenig@amd.com Fixes: 1527f926fd04 ("mm: mmap: fix fput in error path v2") Signed-off-by: Christian König Reviewed-by: Daniel Vetter Cc: Jan Harkes Cc: Miklos Szeredi Cc: Jason Gunthorpe Cc: [5.11+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

2021-02-23T21:39:45Z

Pull idmapped mounts from Christian Brauner: "This introduces idmapped mounts which has been in the making for some time. Simply put, different mounts can expose the same file or directory with different ownership. This initial implementation comes with ports for fat, ext4 and with Christoph's port for xfs with more filesystems being actively worked on by independent people and maintainers. Idmapping mounts handle a wide range of long standing use-cases. Here are just a few: - Idmapped mounts make it possible to easily share files between multiple users or multiple machines especially in complex scenarios. For example, idmapped mounts will be used in the implementation of portable home directories in systemd-homed.service(8) where they allow users to move their home directory to an external storage device and use it on multiple computers where they are assigned different uids and gids. This effectively makes it possible to assign random uids and gids at login time. - It is possible to share files from the host with unprivileged containers without having to change ownership permanently through chown(2). - It is possible to idmap a container's rootfs and without having to mangle every file. For example, Chromebooks use it to share the user's Download folder with their unprivileged containers in their Linux subsystem. - It is possible to share files between containers with non-overlapping idmappings. - Filesystem that lack a proper concept of ownership such as fat can use idmapped mounts to implement discretionary access (DAC) permission checking. - They allow users to efficiently changing ownership on a per-mount basis without having to (recursively) chown(2) all files. In contrast to chown (2) changing ownership of large sets of files is instantenous with idmapped mounts. This is especially useful when ownership of a whole root filesystem of a virtual machine or container is changed. With idmapped mounts a single syscall mount_setattr syscall will be sufficient to change the ownership of all files. - Idmapped mounts always take the current ownership into account as idmappings specify what a given uid or gid is supposed to be mapped to. This contrasts with the chown(2) syscall which cannot by itself take the current ownership of the files it changes into account. It simply changes the ownership to the specified uid and gid. This is especially problematic when recursively chown(2)ing a large set of files which is commong with the aforementioned portable home directory and container and vm scenario. - Idmapped mounts allow to change ownership locally, restricting it to specific mounts, and temporarily as the ownership changes only apply as long as the mount exists. Several userspace projects have either already put up patches and pull-requests for this feature or will do so should you decide to pull this: - systemd: In a wide variety of scenarios but especially right away in their implementation of portable home directories. https://systemd.io/HOME_DIRECTORY/ - container runtimes: containerd, runC, LXD:To share data between host and unprivileged containers, unprivileged and privileged containers, etc. The pull request for idmapped mounts support in containerd, the default Kubernetes runtime is already up for quite a while now: https://github.com/containerd/containerd/pull/4734 - The virtio-fs developers and several users have expressed interest in using this feature with virtual machines once virtio-fs is ported. - ChromeOS: Sharing host-directories with unprivileged containers. I've tightly synced with all those projects and all of those listed here have also expressed their need/desire for this feature on the mailing list. For more info on how people use this there's a bunch of talks about this too. Here's just two recent ones: https://www.cncf.io/wp-content/uploads/2020/12/Rootless-Containers-in-Gitpod.pdf https://fosdem.org/2021/schedule/event/containers_idmap/ This comes with an extensive xfstests suite covering both ext4 and xfs: https://git.kernel.org/brauner/xfstests-dev/h/idmapped_mounts It covers truncation, creation, opening, xattrs, vfscaps, setid execution, setgid inheritance and more both with idmapped and non-idmapped mounts. It already helped to discover an unrelated xfs setgid inheritance bug which has since been fixed in mainline. It will be sent for inclusion with the xfstests project should you decide to merge this. In order to support per-mount idmappings vfsmounts are marked with user namespaces. The idmapping of the user namespace will be used to map the ids of vfs objects when they are accessed through that mount. By default all vfsmounts are marked with the initial user namespace. The initial user namespace is used to indicate that a mount is not idmapped. All operations behave as before and this is verified in the testsuite. Based on prior discussions we want to attach the whole user namespace and not just a dedicated idmapping struct. This allows us to reuse all the helpers that already exist for dealing with idmappings instead of introducing a whole new range of helpers. In addition, if we decide in the future that we are confident enough to enable unprivileged users to setup idmapped mounts the permission checking can take into account whether the caller is privileged in the user namespace the mount is currently marked with. The user namespace the mount will be marked with can be specified by passing a file descriptor refering to the user namespace as an argument to the new mount_setattr() syscall together with the new MOUNT_ATTR_IDMAP flag. The system call follows the openat2() pattern of extensibility. The following conditions must be met in order to create an idmapped mount: - The caller must currently have the CAP_SYS_ADMIN capability in the user namespace the underlying filesystem has been mounted in. - The underlying filesystem must support idmapped mounts. - The mount must not already be idmapped. This also implies that the idmapping of a mount cannot be altered once it has been idmapped. - The mount must be a detached/anonymous mount, i.e. it must have been created by calling open_tree() with the OPEN_TREE_CLONE flag and it must not already have been visible in the filesystem. The last two points guarantee easier semantics for userspace and the kernel and make the implementation significantly simpler. By default vfsmounts are marked with the initial user namespace and no behavioral or performance changes are observed. The manpage with a detailed description can be found here: https://git.kernel.org/brauner/man-pages/c/1d7b902e2875a1ff342e036a9f866a995640aea8 In order to support idmapped mounts, filesystems need to be changed and mark themselves with the FS_ALLOW_IDMAP flag in fs_flags. The patches to convert individual filesystem are not very large or complicated overall as can be seen from the included fat, ext4, and xfs ports. Patches for other filesystems are actively worked on and will be sent out separately. The xfstestsuite can be used to verify that port has been done correctly. The mount_setattr() syscall is motivated independent of the idmapped mounts patches and it's been around since July 2019. One of the most valuable features of the new mount api is the ability to perform mounts based on file descriptors only. Together with the lookup restrictions available in the openat2() RESOLVE_* flag namespace which we added in v5.6 this is the first time we are close to hardened and race-free (e.g. symlinks) mounting and path resolution. While userspace has started porting to the new mount api to mount proper filesystems and create new bind-mounts it is currently not possible to change mount options of an already existing bind mount in the new mount api since the mount_setattr() syscall is missing. With the addition of the mount_setattr() syscall we remove this last restriction and userspace can now fully port to the new mount api, covering every use-case the old mount api could. We also add the crucial ability to recursively change mount options for a whole mount tree, both removing and adding mount options at the same time. This syscall has been requested multiple times by various people and projects. There is a simple tool available at https://github.com/brauner/mount-idmapped that allows to create idmapped mounts so people can play with this patch series. I'll add support for the regular mount binary should you decide to pull this in the following weeks: Here's an example to a simple idmapped mount of another user's home directory: u1001@f2-vm:/$ sudo ./mount --idmap both:1000:1001:1 /home/ubuntu/ /mnt u1001@f2-vm:/$ ls -al /home/ubuntu/ total 28 drwxr-xr-x 2 ubuntu ubuntu 4096 Oct 28 22:07 . drwxr-xr-x 4 root root 4096 Oct 28 04:00 .. -rw------- 1 ubuntu ubuntu 3154 Oct 28 22:12 .bash_history -rw-r--r-- 1 ubuntu ubuntu 220 Feb 25 2020 .bash_logout -rw-r--r-- 1 ubuntu ubuntu 3771 Feb 25 2020 .bashrc -rw-r--r-- 1 ubuntu ubuntu 807 Feb 25 2020 .profile -rw-r--r-- 1 ubuntu ubuntu 0 Oct 16 16:11 .sudo_as_admin_successful -rw------- 1 ubuntu ubuntu 1144 Oct 28 00:43 .viminfo u1001@f2-vm:/$ ls -al /mnt/ total 28 drwxr-xr-x 2 u1001 u1001 4096 Oct 28 22:07 . drwxr-xr-x 29 root root 4096 Oct 28 22:01 .. -rw------- 1 u1001 u1001 3154 Oct 28 22:12 .bash_history -rw-r--r-- 1 u1001 u1001 220 Feb 25 2020 .bash_logout -rw-r--r-- 1 u1001 u1001 3771 Feb 25 2020 .bashrc -rw-r--r-- 1 u1001 u1001 807 Feb 25 2020 .profile -rw-r--r-- 1 u1001 u1001 0 Oct 16 16:11 .sudo_as_admin_successful -rw------- 1 u1001 u1001 1144 Oct 28 00:43 .viminfo u1001@f2-vm:/$ touch /mnt/my-file u1001@f2-vm:/$ setfacl -m u:1001:rwx /mnt/my-file u1001@f2-vm:/$ sudo setcap -n 1001 cap_net_raw+ep /mnt/my-file u1001@f2-vm:/$ ls -al /mnt/my-file -rw-rwxr--+ 1 u1001 u1001 0 Oct 28 22:14 /mnt/my-file u1001@f2-vm:/$ ls -al /home/ubuntu/my-file -rw-rwxr--+ 1 ubuntu ubuntu 0 Oct 28 22:14 /home/ubuntu/my-file u1001@f2-vm:/$ getfacl /mnt/my-file getfacl: Removing leading '/' from absolute path names # file: mnt/my-file # owner: u1001 # group: u1001 user::rw- user:u1001:rwx group::rw- mask::rwx other::r-- u1001@f2-vm:/$ getfacl /home/ubuntu/my-file getfacl: Removing leading '/' from absolute path names # file: home/ubuntu/my-file # owner: ubuntu # group: ubuntu user::rw- user:ubuntu:rwx group::rw- mask::rwx other::r--" * tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: (41 commits) xfs: remove the possibly unused mp variable in xfs_file_compat_ioctl xfs: support idmapped mounts ext4: support idmapped mounts fat: handle idmapped mounts tests: add mount_setattr() selftests fs: introduce MOUNT_ATTR_IDMAP fs: add mount_setattr() fs: add attr_flags_to_mnt_flags helper fs: split out functions to hold writers namespace: only take read lock in do_reconfigure_mnt() mount: make {lock,unlock}_mount_hash() static namespace: take lock_mount_hash() directly when changing flags nfs: do not export idmapped mounts overlayfs: do not mount on top of idmapped mounts ecryptfs: do not mount on top of idmapped mounts ima: handle idmapped mounts apparmor: handle idmapped mounts fs: make helpers idmap mount aware exec: handle idmapped mounts would_dump: handle idmapped mounts ...

ovl: implement volatile-specific fsync error behaviour

2021-01-28T09:22:48Z

Overlayfs's volatile option allows the user to bypass all forced sync calls to the upperdir filesystem. This comes at the cost of safety. We can never ensure that the user's data is intact, but we can make a best effort to expose whether or not the data is likely to be in a bad state. The best way to handle this in the time being is that if an overlayfs's upperdir experiences an error after a volatile mount occurs, that error will be returned on fsync, fdatasync, sync, and syncfs. This is contradictory to the traditional behaviour of VFS which fails the call once, and only raises an error if a subsequent fsync error has occurred, and been raised by the filesystem. One awkward aspect of the patch is that we have to manually set the superblock's errseq_t after the sync_fs callback as opposed to just returning an error from syncfs. This is because the call chain looks something like this: sys_syncfs -> sync_filesystem -> __sync_filesystem -> /* The return value is ignored here sb->s_op->sync_fs(sb) _sync_blockdev /* Where the VFS fetches the error to raise to userspace */ errseq_check_and_advance Because of this we call errseq_set every time the sync_fs callback occurs. Due to the nature of this seen / unseen dichotomy, if the upperdir is an inconsistent state at the initial mount time, overlayfs will refuse to mount, as overlayfs cannot get a snapshot of the upperdir's errseq that will increment on error until the user calls syncfs. Signed-off-by: Sargun Dhillon Suggested-by: Amir Goldstein Reviewed-by: Amir Goldstein Fixes: c86243b090bc ("ovl: provide a mount option "volatile"") Cc: stable@vger.kernel.org Reviewed-by: Vivek Goyal Reviewed-by: Jeff Layton Signed-off-by: Miklos Szeredi

ovl: skip getxattr of security labels

2021-01-28T09:22:48Z

When inode has no listxattr op of its own (e.g. squashfs) vfs_listxattr calls the LSM inode_listsecurity hooks to list the xattrs that LSMs will intercept in inode_getxattr hooks. When selinux LSM is installed but not initialized, it will list the security.selinux xattr in inode_listsecurity, but will not intercept it in inode_getxattr. This results in -ENODATA for a getxattr call for an xattr returned by listxattr. This situation was manifested as overlayfs failure to copy up lower files from squashfs when selinux is built-in but not initialized, because ovl_copy_xattr() iterates the lower inode xattrs by vfs_listxattr() and vfs_getxattr(). ovl_copy_xattr() skips copy up of security labels that are indentified by inode_copy_up_xattr LSM hooks, but it does that after vfs_getxattr(). Since we are not going to copy them, skip vfs_getxattr() of the security labels. Reported-by: Michael Labriola Tested-by: Michael Labriola Link: https://lore.kernel.org/linux-unionfs/2nv9d47zt7.fsf@aldarion.sourceruckus.org/ Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: fix dentry leak in ovl_get_redirect

2021-01-28T09:22:48Z

We need to lock d_parent->d_lock before dget_dlock, or this may have d_lockref updated parallelly like calltrace below which will cause dentry->d_lockref leak and risk a crash. CPU 0 CPU 1 ovl_set_redirect lookup_fast ovl_get_redirect __d_lookup dget_dlock //no lock protection here spin_lock(&dentry->d_lock) dentry->d_lockref.count++ dentry->d_lockref.count++ [ 49.799059] PGD 800000061fed7067 P4D 800000061fed7067 PUD 61fec5067 PMD 0 [ 49.799689] Oops: 0002 [#1] SMP PTI [ 49.800019] CPU: 2 PID: 2332 Comm: node Not tainted 4.19.24-7.20.al7.x86_64 #1 [ 49.800678] Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS 8a46cfe 04/01/2014 [ 49.801380] RIP: 0010:_raw_spin_lock+0xc/0x20 [ 49.803470] RSP: 0018:ffffac6fc5417e98 EFLAGS: 00010246 [ 49.803949] RAX: 0000000000000000 RBX: ffff93b8da3446c0 RCX: 0000000a00000000 [ 49.804600] RDX: 0000000000000001 RSI: 000000000000000a RDI: 0000000000000088 [ 49.805252] RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff993cf040 [ 49.805898] R10: ffff93b92292e580 R11: ffffd27f188a4b80 R12: 0000000000000000 [ 49.806548] R13: 00000000ffffff9c R14: 00000000fffffffe R15: ffff93b8da3446c0 [ 49.807200] FS: 00007ffbedffb700(0000) GS:ffff93b927880000(0000) knlGS:0000000000000000 [ 49.807935] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 49.808461] CR2: 0000000000000088 CR3: 00000005e3f74006 CR4: 00000000003606a0 [ 49.809113] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 49.809758] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 49.810410] Call Trace: [ 49.810653] d_delete+0x2c/0xb0 [ 49.810951] vfs_rmdir+0xfd/0x120 [ 49.811264] do_rmdir+0x14f/0x1a0 [ 49.811573] do_syscall_64+0x5b/0x190 [ 49.811917] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 49.812385] RIP: 0033:0x7ffbf505ffd7 [ 49.814404] RSP: 002b:00007ffbedffada8 EFLAGS: 00000297 ORIG_RAX: 0000000000000054 [ 49.815098] RAX: ffffffffffffffda RBX: 00007ffbedffb640 RCX: 00007ffbf505ffd7 [ 49.815744] RDX: 0000000004449700 RSI: 0000000000000000 RDI: 0000000006c8cd50 [ 49.816394] RBP: 00007ffbedffaea0 R08: 0000000000000000 R09: 0000000000017d0b [ 49.817038] R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000012 [ 49.817687] R13: 00000000072823d8 R14: 00007ffbedffb700 R15: 00000000072823d8 [ 49.818338] Modules linked in: pvpanic cirrusfb button qemu_fw_cfg atkbd libps2 i8042 [ 49.819052] CR2: 0000000000000088 [ 49.819368] ---[ end trace 4e652b8aa299aa2d ]--- [ 49.819796] RIP: 0010:_raw_spin_lock+0xc/0x20 [ 49.821880] RSP: 0018:ffffac6fc5417e98 EFLAGS: 00010246 [ 49.822363] RAX: 0000000000000000 RBX: ffff93b8da3446c0 RCX: 0000000a00000000 [ 49.823008] RDX: 0000000000000001 RSI: 000000000000000a RDI: 0000000000000088 [ 49.823658] RBP: 0000000000000000 R08: 0000000000000000 R09: ffffffff993cf040 [ 49.825404] R10: ffff93b92292e580 R11: ffffd27f188a4b80 R12: 0000000000000000 [ 49.827147] R13: 00000000ffffff9c R14: 00000000fffffffe R15: ffff93b8da3446c0 [ 49.828890] FS: 00007ffbedffb700(0000) GS:ffff93b927880000(0000) knlGS:0000000000000000 [ 49.830725] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 49.832359] CR2: 0000000000000088 CR3: 00000005e3f74006 CR4: 00000000003606a0 [ 49.834085] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 49.835792] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Cc: Fixes: a6c606551141 ("ovl: redirect on rename-dir") Signed-off-by: Liangyan Reviewed-by: Joseph Qi Suggested-by: Al Viro Signed-off-by: Miklos Szeredi