Messages in this thread | | | Date | Mon, 25 Jan 2016 17:10:52 +0100 | From | Ignacy Gawędzki <> | Subject | [PATCH 0/1] OverlayFS: Fix checking permissions during lookup. |
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Hi,
While trying to figure out what exactly is going on with permission checking in OverlayFS, I found a pretty simple way to, so it seems, fix it.
The problem I was having is triggered with the following setup:
drwxr-xr-x lower/ drwx------ lower/foo/ drw-r--r-- lower/boo/bar drwxr-xr-x upper/ drwxr-xr-x upper/foo/
mounted with lower/ as the lowerdir and upper/ as the upperdir.
The issue is that when caches are empty, any user who is not the owner of lower/foo/ and who tries to access foo/bar on the mounted overlay gets EACCES. Once the owner accesses foo/bar, that positive result it cached and other users can access foo/bar as expected.
It would be nice if someone could take a look at the patch that follows and give me some feedback. The fix is simple, but a bit intrusive and I wonder whether this is necessarily the way to go.
Cheers,
Ignacy
Ignacy Gawędzki (1): OverlayFS: Fix checking permissions during lookup.
fs/namei.c | 21 ++++++++++++++++++++- fs/overlayfs/super.c | 2 +- include/linux/namei.h | 1 + 3 files changed, 22 insertions(+), 2 deletions(-)
-- 2.5.0
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