kernel.git/fs/overlayfs/util.c, branch linux-5.0.y

ovl: Do not lose security.capability xattr over metadata file copy-up

2019-03-23T19:11:21Z

commit 993a0b2aec52754f0897b1dab4c453be8217cae5 upstream. If a file has been copied up metadata only, and later data is copied up, upper loses any security.capability xattr it has (underlying filesystem clears it as upon file write). From a user's point of view, this is just a file copy-up and that should not result in losing security.capability xattr. Hence, before data copy up, save security.capability xattr (if any) and restore it on upper after data copy up is complete. Signed-off-by: Vivek Goyal Reviewed-by: Amir Goldstein Fixes: 0c2888749363 ("ovl: A new xattr OVL_XATTR_METACOPY for file on upper") Cc: # v4.19+ Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman

ovl: abstract ovl_inode lock with a helper

2018-10-26T21:34:40Z

The abstraction improves code readabilty (to some). Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: remove the 'locked' argument of ovl_nlink_{start,end}

2018-10-26T21:34:40Z

It just makes the interface strange without adding any significant value. The only case where locked is false and return value is 0 is in ovl_rename() when new is negative, so handle that case explicitly in ovl_rename(). Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: relax requirement for non null uuid of lower fs

2018-10-26T21:34:40Z

We use uuid to associate an overlay lower file handle with a lower layer, so we can accept lower fs with null uuid as long as all lower layers with null uuid are on the same fs. This change allows enabling index and nfs_export features for the setup of single lower fs of type squashfs - squashfs supports file handles, but has a null uuid. This change also allows enabling index and nfs_export features for nested overlayfs, where the lower overlay has nfs_export enabled. Enabling the index feature with single lower squashfs fixes the unionmount-testsuite test: ./run --ov --squashfs --verify As a by-product, if, like the lower squashfs, upper fs also uses the generic export_encode_fh() implementation to export 32bit inode file handles (e.g. ext4), then the xino_auto config/module/mount option will enable unique overlay inode numbers. Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: fix memory leak on unlink of indexed file

2018-09-24T08:54:01Z

The memory leak was detected by kmemleak when running xfstests overlay/051,053 Fixes: caf70cb2ba5d ("ovl: cleanup orphan index entries") Cc: # v4.13 Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: Check redirect on index as well

2018-07-20T07:56:16Z

Right now we seem to check redirect only if upperdentry is found. But it is possible that there is no upperdentry but later we found an index. We need to check redirect on index as well and set it in ovl_inode->redirect. Otherwise link code can assume that dentry does not have redirect and place a new one which breaks things. In my testing overlay/033 test started failing in xfstests. Following are the details. For example do following. $ mkdir lower upper work merged - Make lower dir with 4 links. $ echo "foo" > lower/l0.txt $ ln lower/l0.txt lower/l1.txt $ ln lower/l0.txt lower/l2.txt $ ln lower/l0.txt lower/l3.txt - Mount with index on and metacopy on. $ mount -t overlay -o lowerdir=lower,upperdir=upper,workdir=work,\ index=on,metacopy=on none merged - Link lower $ ln merged/l0.txt merged/l4.txt (This will metadata copy up of l0.txt and put an absolute redirect /l0.txt) $ echo 2 > /proc/sys/vm/drop/caches $ ls merged/l1.txt (Now l1.txt will be looked up. There is no upper dentry but there is lower dentry and index will be found. We don't check for redirect on index, hence ovl_inode->redirect will be NULL.) - Link Upper $ ln merged/l4.txt merged/l5.txt (Lookup of l4.txt will use inode from l1.txt lookup which is still in cache. It has ovl_inode->redirect NULL, hence link will put a new redirect and replace /l0.txt with /l4.txt - Drop caches. echo 2 > /proc/sys/vm/drop_caches - List l1.txt and it returns -ESTALE $ ls merged/l0.txt (It returns stale because, we found a metacopy of l0.txt in upper and it has redirect l4.txt but there is no file named l4.txt in lower layer. So lower data copy is not found and -ESTALE is returned.) So problem here is that we did not process redirect on index. Check redirect on index as well and then problem is fixed. Signed-off-by: Vivek Goyal Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: Do not set dentry type ORIGIN for broken hardlinks

2018-07-20T07:56:14Z

If a dentry has copy up origin, we set flag OVL_PATH_ORIGIN. So far this decision was easy that we had to check only for oe->numlower and if it is non-zero, we knew there is copy up origin. (For non-dir we installed origin dentry in lowerstack[0]). But we don't create ORGIN xattr for broken hardlinks (index=off). And with metacopy feature it is possible that we will install lowerstack[0] but ORIGIN xattr is not there. It is data dentry of upper metacopy dentry which has been found using regular name based lookup or using REDIRECT. So with addition of this new case, just presence of oe->numlower is not sufficient to guarantee that ORIGIN xattr is present. So to differentiate between two cases, look at OVL_CONST_INO flag. If this flag is set and upperdentry is there, that means it can be marked as type ORIGIN. OVL_CONST_INO is not set if lower hardlink is broken or will be broken over copy up. Signed-off-by: Vivek Goyal Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: Treat metacopy dentries as type OVL_PATH_MERGE

2018-07-20T07:56:13Z

Right now OVL_PATH_MERGE is used only for merged directories. But conceptually, a metacopy dentry (backed by a lower data dentry) is a merged entity as well. So mark metacopy dentries as OVL_PATH_MERGE and ovl_rename() makes use of this property later to set redirect on a metacopy file. Signed-off-by: Vivek Goyal Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: Add helper ovl_inode_realdata()

2018-07-20T07:56:11Z

Add an helper to retrieve real data inode associated with overlay inode. This helper will ignore all metacopy inodes and will return only the real inode which has data. Signed-off-by: Vivek Goyal Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi

ovl: Store lower data inode in ovl_inode

2018-07-20T07:56:11Z

Right now ovl_inode stores inode pointer for lower inode. This helps with quickly getting lower inode given overlay inode (ovl_inode_lower()). Now with metadata only copy-up, we can have metacopy inode in middle layer as well and inode containing data can be different from ->lower. I need to be able to open the real file in ovl_open_realfile() and for that I need to quickly find the lower data inode. Hence store lower data inode also in ovl_inode. Also provide an helper ovl_inode_lowerdata() to access this field. Signed-off-by: Vivek Goyal Reviewed-by: Amir Goldstein Signed-off-by: Miklos Szeredi