Miklos, Vivek, Following discussion on following an unsafe non-dir origin [1] and in a addition to a fix for the reported null uuid case [2] and to Vivek's doc clarification [3], I am proposing to piggy back existing config redirect_dir=nofollow to also not follow non-dir origin. Like in the case of non-dir origin, following redirects behavior was added with no opt-out option in kernel v4.10. Later security concerns about following malformed redirects resulted in the redirect_dir=nofollow config option. Without giving too much thought into how unsafe it can be to follow a bad origin, there is very low motication IMO to follow non-dir origin with redirect_dir=nofollow, because it is a configuration that prefers safety over correctness, so it just seems like the right thing to do. The first two patches are independent bug fixes related to read-only NFS export, which can be taken regardless of non-dir origin nofollow. FYI, I found those bugs because I am using ro,index=off NFS export configuration for the new overlay fsnotify snaphsot series. Thanks, Amir. [1] https://lore.kernel.org/linux-unionfs/CAJfpegv9h7ubuGy_6K4OCdZd3R7Z4HGmCDB2L7mO5bVoGd6MSA@xxxxxxxxxxxxxx/ [2] https://lore.kernel.org/linux-unionfs/20200708131613.30038-1-amir73il@xxxxxxxxx/ [3] https://lore.kernel.org/linux-unionfs/20200709140220.GC150543@xxxxxxxxxx/ Amir Goldstein (3): ovl: force read-only sb on failure to create index dir ovl: fix mount option checks for nfs_export with no upperdir ovl: do not follow non-dir origin with redirect_dir=nofollow Documentation/filesystems/overlayfs.rst | 4 +-- fs/overlayfs/namei.c | 2 +- fs/overlayfs/super.c | 42 ++++++++++++++----------- 3 files changed, 27 insertions(+), 21 deletions(-) -- 2.17.1
