kernel.git/fs/overlayfs, branch linux-4.19.y

ovl: skip overlayfs superblocks at global sync

2023-12-08T07:43:26Z

[ Upstream commit 32b1924b210a70dcacdf65abd687c5ef86a67541 ] Stacked filesystems like overlayfs has no own writeback, but they have to forward syncfs() requests to backend for keeping data integrity. During global sync() each overlayfs instance calls method ->sync_fs() for backend although it itself is in global list of superblocks too. As a result one syscall sync() could write one superblock several times and send multiple disk barriers. This patch adds flag SB_I_SKIP_SYNC into sb->sb_iflags to avoid that. Reported-by: Dmitry Monakhov Signed-off-by: Konstantin Khlebnikov Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi Stable-dep-of: b836c4d29f27 ("ima: detect changes to the backing overlay file") Signed-off-by: Sasha Levin

overlayfs: set ctime when setting mtime and atime

2023-10-25T09:16:53Z

[ Upstream commit 03dbab3bba5f009d053635c729d1244f2c8bad38 ] Nathan reported that he was seeing the new warning in setattr_copy_mgtime pop when starting podman containers. Overlayfs is trying to set the atime and mtime via notify_change without also setting the ctime. POSIX states that when the atime and mtime are updated via utimes() that we must also update the ctime to the current time. The situation with overlayfs copy-up is analogies, so add ATTR_CTIME to the bitmask. notify_change will fill in the value. Reported-by: Nathan Chancellor Signed-off-by: Jeff Layton Tested-by: Nathan Chancellor Acked-by: Christian Brauner Acked-by: Amir Goldstein Message-Id: <20230913-ctime-v1-1-c6bc509cbc27@kernel.org> Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

new helper: lookup_positive_unlocked()

2023-09-23T08:47:59Z

[ Upstream commit 6c2d4798a8d16cf4f3a28c3cd4af4f1dcbbb4d04 ] Most of the callers of lookup_one_len_unlocked() treat negatives are ERR_PTR(-ENOENT). Provide a helper that would do just that. Note that a pinned positive dentry remains positive - it's ->d_inode is stable, etc.; a pinned _negative_ dentry can become positive at any point as long as you are not holding its parent at least shared. So using lookup_one_len_unlocked() needs to be careful; lookup_positive_unlocked() is safer and that's what the callers end up open-coding anyway. Signed-off-by: Al Viro Stable-dep-of: 0d5a4f8f775f ("fs: Fix error checking for d_hash_and_lookup()") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

treewide: Remove uninitialized_var() usage

2023-08-11T09:45:01Z

commit 3f649ab728cda8038259d8f14492fe400fbab911 upstream. Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var$([^$]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe # IB Acked-by: Kalle Valo # wireless drivers Reviewed-by: Chao Yu # erofs Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman

ovl: Use ovl mounter's fsuid and fsgid in ovl_link()

2023-01-18T10:30:40Z

commit 5b0db51215e895a361bc63132caa7cca36a53d6a upstream. There is a wrong case of link() on overlay: $ mkdir /lower /fuse /merge $ mount -t fuse /fuse $ mkdir /fuse/upper /fuse/work $ mount -t overlay /merge -o lowerdir=/lower,upperdir=/fuse/upper,\ workdir=work $ touch /merge/file $ chown bin.bin /merge/file // the file's caller becomes "bin" $ ln /merge/file /merge/lnkfile Then we will get an error(EACCES) because fuse daemon checks the link()'s caller is "bin", it denied this request. In the changing history of ovl_link(), there are two key commits: The first is commit bb0d2b8ad296 ("ovl: fix sgid on directory") which overrides the cred's fsuid/fsgid using the new inode. The new inode's owner is initialized by inode_init_owner(), and inode->fsuid is assigned to the current user. So the override fsuid becomes the current user. We know link() is actually modifying the directory, so the caller must have the MAY_WRITE permission on the directory. The current caller may should have this permission. This is acceptable to use the caller's fsuid. The second is commit 51f7e52dc943 ("ovl: share inode for hard link") which removed the inode creation in ovl_link(). This commit move inode_init_owner() into ovl_create_object(), so the ovl_link() just give the old inode to ovl_create_or_link(). Then the override fsuid becomes the old inode's fsuid, neither the caller nor the overlay's mounter! So this is incorrect. Fix this bug by using ovl mounter's fsuid/fsgid to do underlying fs's link(). Link: https://lore.kernel.org/all/20220817102952.xnvesg3a7rbv576x@wittgenstein/T Link: https://lore.kernel.org/lkml/20220825130552.29587-1-zhangtianci.1997@bytedance.com/t Signed-off-by: Zhang Tianci Signed-off-by: Jiachen Zhang Reviewed-by: Christian Brauner (Microsoft) Fixes: 51f7e52dc943 ("ovl: share inode for hard link") Cc: # v4.8 Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: drop WARN_ON() dentry is NULL in ovl_encode_fh()

2022-08-25T09:14:54Z

commit dd524b7f317de8d31d638cbfdc7be4cf9b770e42 upstream. Some code paths cannot guarantee the inode have any dentry alias. So WARN_ON() all !dentry may flood the kernel logs. For example, when an overlayfs inode is watched by inotifywait (1), and someone is trying to read the /proc/$(pidof inotifywait)/fdinfo/INOTIFY_FD, at that time if the dentry has been reclaimed by kernel (such as echo 2 > /proc/sys/vm/drop_caches), there will be a WARN_ON(). The printed call stack would be like: ? show_mark_fhandle+0xf0/0xf0 show_mark_fhandle+0x4a/0xf0 ? show_mark_fhandle+0xf0/0xf0 ? seq_vprintf+0x30/0x50 ? seq_printf+0x53/0x70 ? show_mark_fhandle+0xf0/0xf0 inotify_fdinfo+0x70/0x90 show_fdinfo.isra.4+0x53/0x70 seq_show+0x130/0x170 seq_read+0x153/0x440 vfs_read+0x94/0x150 ksys_read+0x5f/0xe0 do_syscall_64+0x59/0x1e0 entry_SYSCALL_64_after_hwframe+0x44/0xa9 So let's drop WARN_ON() to avoid kernel log flooding. Reported-by: Hongbo Yin Signed-off-by: Jiachen Zhang Signed-off-by: Tianci Zhang Fixes: 8ed5eec9d6c4 ("ovl: encode pure upper file handles") Cc: # v4.16 Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: fix warning in ovl_create_real()

2021-12-22T08:19:04Z

commit 1f5573cfe7a7056e80a92c7a037a3e69f3a13d1c upstream. Syzbot triggered the following warning in ovl_workdir_create() -> ovl_create_real(): if (!err && WARN_ON(!newdentry->d_inode)) { The reason is that the cgroup2 filesystem returns from mkdir without instantiating the new dentry. Weird filesystems such as this will be rejected by overlayfs at a later stage during setup, but to prevent such a warning, call ovl_mkdir_real() directly from ovl_workdir_create() and reject this case early. Reported-and-tested-by: syzbot+75eab84fd0af9e8bf66b@syzkaller.appspotmail.com Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: fix missing negative dentry check in ovl_rename()

2021-10-13T08:10:50Z

commit a295aef603e109a47af355477326bd41151765b6 upstream. The following reproducer mkdir lower upper work merge touch lower/old touch lower/new mount -t overlay overlay -olowerdir=lower,upperdir=upper,workdir=work merge rm merge/new mv merge/old merge/new & unlink upper/new may result in this race: PROCESS A: rename("merge/old", "merge/new"); overwrite=true,ovl_lower_positive(old)=true, ovl_dentry_is_whiteout(new)=true -> flags |= RENAME_EXCHANGE PROCESS B: unlink("upper/new"); PROCESS A: lookup newdentry in new_upperdir call vfs_rename() with negative newdentry and RENAME_EXCHANGE Fix by adding the missing check for negative newdentry. Signed-off-by: Zheng Liang Fixes: e9be9d5e76e3 ("overlay filesystem") Cc: # v3.18 Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: fix BUG_ON() in may_delete() when called from ovl_cleanup()

2021-09-22T09:48:09Z

commit 52d5a0c6bd8a89f460243ed937856354f8f253a3 upstream. If function ovl_instantiate() returns an error, ovl_cleanup will be called and try to remove newdentry from wdir, but the newdentry has been moved to udir at this time. This will causes BUG_ON(victim->d_parent->d_inode != dir) in fs/namei.c:may_delete. Signed-off-by: chenying Fixes: 01b39dcc9568 ("ovl: use inode_insert5() to hash a newly created inode") Link: https://lore.kernel.org/linux-unionfs/e6496a94-a161-dc04-c38a-d2544633acb4@bytedance.com/ Cc: # v4.18 Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: fix missing revert_creds() on error path

2021-05-22T08:59:26Z

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