kernel/linux.git/fs/inode.c, branch linux-6.0.y

fs: fix UAF/GPF bug in nilfs_mdt_destroy

2022-10-12T07:39:03+00:00

commit 2e488f13755ffbb60f307e991b27024716a33b29 upstream. In alloc_inode, inode_init_always() could return -ENOMEM if security_inode_alloc() fails, which causes inode->i_private uninitialized. Then nilfs_is_metadata_file_inode() returns true and nilfs_free_inode() wrongly calls nilfs_mdt_destroy(), which frees the uninitialized inode->i_private and leads to crashes(e.g., UAF/GPF). Fix this by moving security_inode_alloc just prior to this_cpu_inc(nr_inodes) Link: https://lkml.kernel.org/r/CAFcO6XOcf1Jj2SeGt=jJV59wmhESeSKpfR0omdFRq+J9nD1vfQ@mail.gmail.com Reported-by: butt3rflyh4ck Reported-by: Hao Sun Reported-by: Jiacheng Xu Reviewed-by: Christian Brauner (Microsoft) Signed-off-by: Dongliang Mu Cc: Al Viro Cc: stable@vger.kernel.org Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman

fs: __file_remove_privs(): restore call to inode_has_no_xattr()

2022-08-18T07:39:33+00:00

This restores the call to inode_has_no_xattr() in the function __file_remove_privs(). In case the dentry_meeds_remove_privs() returned 0, the function inode_has_no_xattr() was not called. Signed-off-by: Stefan Roesch Fixes: faf99b563558 ("fs: add __remove_file_privs() with flags parameter") Reviewed-by: Christian Brauner (Microsoft) Link: https://lore.kernel.org/r/20220816153158.1925040-1-shr@fb.com Signed-off-by: Christian Brauner (Microsoft)

Merge tag 'ceph-for-5.20-rc1' of https://github.com/ceph/ceph-client

2022-08-11T19:41:07+00:00

Pull ceph updates from Ilya Dryomov: "We have a good pile of various fixes and cleanups from Xiubo, Jeff, Luis and others, almost exclusively in the filesystem. Several patches touch files outside of our normal purview to set the stage for bringing in Jeff's long awaited ceph+fscrypt series in the near future. All of them have appropriate acks and sat in linux-next for a while" * tag 'ceph-for-5.20-rc1' of https://github.com/ceph/ceph-client: (27 commits) libceph: clean up ceph_osdc_start_request prototype libceph: fix ceph_pagelist_reserve() comment typo ceph: remove useless check for the folio ceph: don't truncate file in atomic_open ceph: make f_bsize always equal to f_frsize ceph: flush the dirty caps immediatelly when quota is approaching libceph: print fsid and epoch with osd id libceph: check pointer before assigned to "c->rules[]" ceph: don't get the inline data for new creating files ceph: update the auth cap when the async create req is forwarded ceph: make change_auth_cap_ses a global symbol ceph: fix incorrect old_size length in ceph_mds_request_args ceph: switch back to testing for NULL folio->private in ceph_dirty_folio ceph: call netfs_subreq_terminated with was_async == false ceph: convert to generic_file_llseek ceph: fix the incorrect comment for the ceph_mds_caps struct ceph: don't leak snap_rwsem in handle_cap_grant ceph: prevent a client from exceeding the MDS maximum xattr size ceph: choose auth MDS for getxattr with the Xs caps ceph: add session already open notify support ...

Merge tag 'fs.setgid.v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux

2022-08-09T16:52:28+00:00

Pull setgid updates from Christian Brauner: "This contains the work to move setgid stripping out of individual filesystems and into the VFS itself. Creating files that have both the S_IXGRP and S_ISGID bit raised in directories that themselves have the S_ISGID bit set requires additional privileges to avoid security issues. When a filesystem creates a new inode it needs to take care that the caller is either in the group of the newly created inode or they have CAP_FSETID in their current user namespace and are privileged over the parent directory of the new inode. If any of these two conditions is true then the S_ISGID bit can be raised for an S_IXGRP file and if not it needs to be stripped. However, there are several key issues with the current implementation: - S_ISGID stripping logic is entangled with umask stripping. For example, if the umask removes the S_IXGRP bit from the file about to be created then the S_ISGID bit will be kept. The inode_init_owner() helper is responsible for S_ISGID stripping and is called before posix_acl_create(). So we can end up with two different orderings: 1. FS without POSIX ACL support First strip umask then strip S_ISGID in inode_init_owner(). In other words, if a filesystem doesn't support or enable POSIX ACLs then umask stripping is done directly in the vfs before calling into the filesystem: 2. FS with POSIX ACL support First strip S_ISGID in inode_init_owner() then strip umask in posix_acl_create(). In other words, if the filesystem does support POSIX ACLs then unmask stripping may be done in the filesystem itself when calling posix_acl_create(). Note that technically filesystems are free to impose their own ordering between posix_acl_create() and inode_init_owner() meaning that there's additional ordering issues that influence S_ISGID inheritance. (Note that the commit message of commit 1639a49ccdce ("fs: move S_ISGID stripping into the vfs_*() helpers") gets the ordering between inode_init_owner() and posix_acl_create() the wrong way around. I realized this too late.) - Filesystems that don't rely on inode_init_owner() don't get S_ISGID stripping logic. While that may be intentional (e.g. network filesystems might just defer setgid stripping to a server) it is often just a security issue. Note that mandating the use of inode_init_owner() was proposed as an alternative solution but that wouldn't fix the ordering issues and there are examples such as afs where the use of inode_init_owner() isn't possible. In any case, we should also try the cleaner and generalized solution first before resorting to this approach. - We still have S_ISGID inheritance bugs years after the initial round of S_ISGID inheritance fixes: e014f37db1a2 ("xfs: use setattr_copy to set vfs inode attributes") 01ea173e103e ("xfs: fix up non-directory creation in SGID directories") fd84bfdddd16 ("ceph: fix up non-directory creation in SGID directories") All of this led us to conclude that the current state is too messy. While we won't be able to make it completely clean as posix_acl_create() is still a filesystem specific call we can improve the S_SIGD stripping situation quite a bit by hoisting it out of inode_init_owner() and into the respective vfs creation operations. The obvious advantage is that we don't need to rely on individual filesystems getting S_ISGID stripping right and instead can standardize the ordering between S_ISGID and umask stripping directly in the VFS. A few short implementation notes: - The stripping logic needs to happen in vfs_*() helpers for the sake of stacking filesystems such as overlayfs that rely on these helpers taking care of S_ISGID stripping. - Security hooks have never seen the mode as it is ultimately seen by the filesystem because of the ordering issue we mentioned. Nothing is changed for them. We simply continue to strip the umask before passing the mode down to the security hooks. - The following filesystems use inode_init_owner() and thus relied on S_ISGID stripping: spufs, 9p, bfs, btrfs, ext2, ext4, f2fs, hfsplus, hugetlbfs, jfs, minix, nilfs2, ntfs3, ocfs2, omfs, overlayfs, ramfs, reiserfs, sysv, ubifs, udf, ufs, xfs, zonefs, bpf, tmpfs. We've audited all callchains as best as we could. More details can be found in the commit message to 1639a49ccdce ("fs: move S_ISGID stripping into the vfs_*() helpers")" * tag 'fs.setgid.v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: ceph: rely on vfs for setgid stripping fs: move S_ISGID stripping into the vfs_*() helpers fs: Add missing umask strip in vfs_tmpfile fs: add mode_strip_sgid() helper

Merge tag 'folio-6.0' of git://git.infradead.org/users/willy/pagecache

2022-08-03T17:35:43+00:00

Pull folio updates from Matthew Wilcox: - Fix an accounting bug that made NR_FILE_DIRTY grow without limit when running xfstests - Convert more of mpage to use folios - Remove add_to_page_cache() and add_to_page_cache_locked() - Convert find_get_pages_range() to filemap_get_folios() - Improvements to the read_cache_page() family of functions - Remove a few unnecessary checks of PageError - Some straightforward filesystem conversions to use folios - Split PageMovable users out from address_space_operations into their own movable_operations - Convert aops->migratepage to aops->migrate_folio - Remove nobh support (Christoph Hellwig) * tag 'folio-6.0' of git://git.infradead.org/users/willy/pagecache: (78 commits) fs: remove the NULL get_block case in mpage_writepages fs: don't call ->writepage from __mpage_writepage fs: remove the nobh helpers jfs: stop using the nobh helper ext2: remove nobh support ntfs3: refactor ntfs_writepages mm/folio-compat: Remove migration compatibility functions fs: Remove aops->migratepage() secretmem: Convert to migrate_folio hugetlb: Convert to migrate_folio aio: Convert to migrate_folio f2fs: Convert to filemap_migrate_folio() ubifs: Convert to filemap_migrate_folio() btrfs: Convert btrfs_migratepage to migrate_folio mm/migrate: Add filemap_migrate_folio() mm/migrate: Convert migrate_page() to migrate_folio() nfs: Convert to migrate_folio btrfs: Convert btree_migratepage to migrate_folio mm/migrate: Convert expected_page_refs() to folio_expected_refs() mm/migrate: Convert buffer_migrate_page() to buffer_migrate_folio() ...

fs: change test in inode_insert5 for adding to the sb list

2022-08-02T22:54:11+00:00

inode_insert5 currently looks at I_CREATING to decide whether to insert the inode into the sb list. This test is a bit ambiguous, as I_CREATING state is not directly related to that list. This test is also problematic for some upcoming ceph changes to add fscrypt support. We need to be able to allocate an inode using new_inode and insert it into the hash later iff we end up using it, and doing that now means that we double add it and corrupt the list. What we really want to know in this test is whether the inode is already in its superblock list, and then add it if it isn't. Have it test for list_empty instead and ensure that we always initialize the list by doing it in inode_init_once. It's only ever removed from the list with list_del_init, so that should be sufficient. Suggested-by: Al Viro Signed-off-by: Jeff Layton Reviewed-by: Christoph Hellwig Reviewed-by: Dave Chinner Signed-off-by: Ilya Dryomov

fs: Add async write file modification handling.

2022-07-25T00:39:32+00:00

This adds a file_modified_async() function to return -EAGAIN if the request either requires to remove privileges or needs to update the file modification time. This is required for async buffered writes, so the request gets handled in the io worker of io-uring. Signed-off-by: Stefan Roesch Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Reviewed-by: Christian Brauner (Microsoft) Reviewed-by: Darrick J. Wong Link: https://lore.kernel.org/r/20220623175157.1715274-11-shr@fb.com Signed-off-by: Jens Axboe

fs: Split off inode_needs_update_time and __file_update_time

2022-07-25T00:39:31+00:00

This splits off the functions inode_needs_update_time() and __file_update_time() from the function file_update_time(). This is required to support async buffered writes. No intended functional changes in this patch. Signed-off-by: Stefan Roesch Reviewed-by: Jan Kara Reviewed-by: Christian Brauner (Microsoft) Reviewed-by: Darrick J. Wong Link: https://lore.kernel.org/r/20220623175157.1715274-10-shr@fb.com Signed-off-by: Jens Axboe

fs: add __remove_file_privs() with flags parameter

2022-07-25T00:39:31+00:00

This adds the function __remove_file_privs, which allows the caller to pass the kiocb flags parameter. No intended functional changes in this patch. Signed-off-by: Stefan Roesch Reviewed-by: Christoph Hellwig Reviewed-by: Jan Kara Reviewed-by: Christian Brauner (Microsoft) Reviewed-by: Darrick J. Wong Link: https://lore.kernel.org/r/20220623175157.1715274-9-shr@fb.com Signed-off-by: Jens Axboe

fs: move S_ISGID stripping into the vfs_*() helpers

2022-07-21T09:34:16+00:00

Move setgid handling out of individual filesystems and into the VFS itself to stop the proliferation of setgid inheritance bugs. Creating files that have both the S_IXGRP and S_ISGID bit raised in directories that themselves have the S_ISGID bit set requires additional privileges to avoid security issues. When a filesystem creates a new inode it needs to take care that the caller is either in the group of the newly created inode or they have CAP_FSETID in their current user namespace and are privileged over the parent directory of the new inode. If any of these two conditions is true then the S_ISGID bit can be raised for an S_IXGRP file and if not it needs to be stripped. However, there are several key issues with the current implementation: * S_ISGID stripping logic is entangled with umask stripping. If a filesystem doesn't support or enable POSIX ACLs then umask stripping is done directly in the vfs before calling into the filesystem. If the filesystem does support POSIX ACLs then unmask stripping may be done in the filesystem itself when calling posix_acl_create(). Since umask stripping has an effect on S_ISGID inheritance, e.g., by stripping the S_IXGRP bit from the file to be created and all relevant filesystems have to call posix_acl_create() before inode_init_owner() where we currently take care of S_ISGID handling S_ISGID handling is order dependent. IOW, whether or not you get a setgid bit depends on POSIX ACLs and umask and in what order they are called. Note that technically filesystems are free to impose their own ordering between posix_acl_create() and inode_init_owner() meaning that there's additional ordering issues that influence S_SIGID inheritance. * Filesystems that don't rely on inode_init_owner() don't get S_ISGID stripping logic. While that may be intentional (e.g. network filesystems might just defer setgid stripping to a server) it is often just a security issue. This is not just ugly it's unsustainably messy especially since we do still have bugs in this area years after the initial round of setgid bugfixes. So the current state is quite messy and while we won't be able to make it completely clean as posix_acl_create() is still a filesystem specific call we can improve the S_SIGD stripping situation quite a bit by hoisting it out of inode_init_owner() and into the vfs creation operations. This means we alleviate the burden for filesystems to handle S_ISGID stripping correctly and can standardize the ordering between S_ISGID and umask stripping in the vfs. We add a new helper vfs_prepare_mode() so S_ISGID handling is now done in the VFS before umask handling. This has S_ISGID handling is unaffected unaffected by whether umask stripping is done by the VFS itself (if no POSIX ACLs are supported or enabled) or in the filesystem in posix_acl_create() (if POSIX ACLs are supported). The vfs_prepare_mode() helper is called directly in vfs_*() helpers that create new filesystem objects. We need to move them into there to make sure that filesystems like overlayfs hat have callchains like: sys_mknod() -> do_mknodat(mode) -> .mknod = ovl_mknod(mode) -> ovl_create(mode) -> vfs_mknod(mode) get S_ISGID stripping done when calling into lower filesystems via vfs_*() creation helpers. Moving vfs_prepare_mode() into e.g. vfs_mknod() takes care of that. This is in any case semantically cleaner because S_ISGID stripping is VFS security requirement. Security hooks so far have seen the mode with the umask applied but without S_ISGID handling done. The relevant hooks are called outside of vfs_*() creation helpers so by calling vfs_prepare_mode() from vfs_*() helpers the security hooks would now see the mode without umask stripping applied. For now we fix this by passing the mode with umask settings applied to not risk any regressions for LSM hooks. IOW, nothing changes for LSM hooks. It is worth pointing out that security hooks never saw the mode that is seen by the filesystem when actually creating the file. They have always been completely misplaced for that to work. The following filesystems use inode_init_owner() and thus relied on S_ISGID stripping: spufs, 9p, bfs, btrfs, ext2, ext4, f2fs, hfsplus, hugetlbfs, jfs, minix, nilfs2, ntfs3, ocfs2, omfs, overlayfs, ramfs, reiserfs, sysv, ubifs, udf, ufs, xfs, zonefs, bpf, tmpfs. All of the above filesystems end up calling inode_init_owner() when new filesystem objects are created through the ->mkdir(), ->mknod(), ->create(), ->tmpfile(), ->rename() inode operations. Since directories always inherit the S_ISGID bit with the exception of xfs when irix_sgid_inherit mode is turned on S_ISGID stripping doesn't apply. The ->symlink() and ->link() inode operations trivially inherit the mode from the target and the ->rename() inode operation inherits the mode from the source inode. All other creation inode operations will get S_ISGID handling via vfs_prepare_mode() when called from their relevant vfs_*() helpers. In addition to this there are filesystems which allow the creation of filesystem objects through ioctl()s or - in the case of spufs - circumventing the vfs in other ways. If filesystem objects are created through ioctl()s the vfs doesn't know about it and can't apply regular permission checking including S_ISGID logic. Therfore, a filesystem relying on S_ISGID stripping in inode_init_owner() in their ioctl() callpath will be affected by moving this logic into the vfs. We audited those filesystems: * btrfs allows the creation of filesystem objects through various ioctls(). Snapshot creation literally takes a snapshot and so the mode is fully preserved and S_ISGID stripping doesn't apply. Creating a new subvolum relies on inode_init_owner() in btrfs_new_subvol_inode() but only creates directories and doesn't raise S_ISGID. * ocfs2 has a peculiar implementation of reflinks. In contrast to e.g. xfs and btrfs FICLONE/FICLONERANGE ioctl() that is only concerned with the actual extents ocfs2 uses a separate ioctl() that also creates the target file. Iow, ocfs2 circumvents the vfs entirely here and did indeed rely on inode_init_owner() to strip the S_ISGID bit. This is the only place where a filesystem needs to call mode_strip_sgid() directly but this is self-inflicted pain. * spufs doesn't go through the vfs at all and doesn't use ioctl()s either. Instead it has a dedicated system call spufs_create() which allows the creation of filesystem objects. But spufs only creates directories and doesn't allo S_SIGID bits, i.e. it specifically only allows 0777 bits. * bpf uses vfs_mkobj() but also doesn't allow S_ISGID bits to be created. The patch will have an effect on ext2 when the EXT2_MOUNT_GRPID mount option is used, on ext4 when the EXT4_MOUNT_GRPID mount option is used, and on xfs when the XFS_FEAT_GRPID mount option is used. When any of these filesystems are mounted with their respective GRPID option then newly created files inherit the parent directories group unconditionally. In these cases non of the filesystems call inode_init_owner() and thus did never strip the S_ISGID bit for newly created files. Moving this logic into the VFS means that they now get the S_ISGID bit stripped. This is a user visible change. If this leads to regressions we will either need to figure out a better way or we need to revert. However, given the various setgid bugs that we found just in the last two years this is a regression risk we should take. Associated with this change is a new set of fstests to enforce the semantics for all new filesystems. Link: https://lore.kernel.org/ceph-devel/20220427092201.wvsdjbnc7b4dttaw@wittgenstein [1] Link: e014f37db1a2 ("xfs: use setattr_copy to set vfs inode attributes") [2] Link: 01ea173e103e ("xfs: fix up non-directory creation in SGID directories") [3] Link: fd84bfdddd16 ("ceph: fix up non-directory creation in SGID directories") [4] Link: https://lore.kernel.org/r/1657779088-2242-3-git-send-email-xuyang2018.jy@fujitsu.com Suggested-by: Dave Chinner Suggested-by: Christian Brauner (Microsoft) Reviewed-by: Darrick J. Wong Reviewed-and-Tested-by: Jeff Layton Signed-off-by: Yang Xu [: rewrote commit message] Signed-off-by: Christian Brauner (Microsoft)