On Fri, Oct 6, 2023 at 4:03 PM Sebastian Wick <sebastian.wick@xxxxxxxxxx> wrote: > > On Fri, Sep 29, 2023 at 07:44:09AM +0300, Amir Goldstein wrote: > > On Fri, Sep 29, 2023 at 4:08 AM Ryan Hendrickson > > <ryan.hendrickson@xxxxxxxxxxxx> wrote: > > > > > > Up to and including kernel 6.4.15, it was possible to have commas in > > > the lowerdir/upperdir/workdir paths used by overlayfs, provided they were > > > escaped with backslashes: > > > > > > mkdir /tmp/test-lower, /tmp/test-upper /tmp/test-work /tmp/test > > > mount -t overlay overlay -o 'lowerdir=/tmp/test-lower\,,upperdir=/tmp/test-upper,workdir=/tmp/test-work' /tmp/test > > > > > > In 6.5.2 and 6.5.5, this no longer works; dmesg reports that overlayfs > > > can't resolve '/tmp/test-lower' (without the comma). > > > > > > I see that there is a commit between the 6.4 and 6.5 lines titled [ovl: > > > port to new mount api][1]. I haven't compiled a kernel before and after > > > this commit to verify, but based on the code it deletes I strongly suspect > > > that it, or if not then one of the ovl commits committed on the same day, > > > is responsible for this change. > > > > > > [1]: https://github.com/torvalds/linux/commit/1784fbc2ed9c888ea4e895f30a53207ed7ee8208 > > > > > > > That's a good guess. > > It helps to CC the author of the patch in this case ;-) > > > > > Does this count as a regression? > > > > "used to work, does not work now" is pretty close to a dictionary > > definition of a regression :) > > > > The question is whether we should fix it. > > The rule of thumb is that if users complain than we need to fix it, > > but it's a corner case and if the only users that complained are willing > > to work around the problem (hint hint) then we may not need to fix it. > > It would be nice to have this fixed. A more general question: will you > commit on keeping the escaping stable from now on or do we have to > expect changes at any point in the future? > I prefer that escaping would be handled in userspace, now that the new mount API allows that, so deferring the question to libmount maintainer. Thanks, Amir. > In that case we would just reject any string contianing characters that > need escaping. > > > > I can't find documentation for this > > > escaping feature anywhere, even as it pertains to the non-comma characters > > > '\\' and ':' (which, I've tested, can still be escaped as expected), so > > > perhaps it was never properly supported? But a search for escaping commas > > > in overlayfs turns up resources like [this post][2], suggesting that there > > > are others who figured this out and expect it to work. > > > > > > [2]: https://unix.stackexchange.com/a/552640 > > > > > > Is there a new way to escape commas for overlayfs options? > > > > > > > Deferring the question to Christian. > > > > Thanks, > > Amir. >
