On Wed, 2023-04-19 02:09:37 +0000, Casey Schaufler wrote: > > On 4/18/2023 5:23 PM, Mengchi Cheng wrote: > > Hello, > > > > On the overlay ext4 file system, we found that transmute flag is not > > inherited by newly created sub-directories. The issue can be recreated on > > the newest kernel(6.3.0-rc6) on qemux86-64 with following steps. > > > > /data directory is mounted on /dev/vdb which is a ext4 fs. It is remounted > > as an overlay again to upperdir /home/root/data. > > # mount -t overlay overlay -o lowerdir=/data,upperdir=/home/root/data,workdir=/home/root/data_work /data > > Add a new smack rule and set label and flag to /data directory. > > # echo "_ system rwxatl" > /sys/fs/smackfs/load2 > > # chsmack -a "system" /data > > # chsmack -t /data > > Create directories under /data. > > # mkdir -p /data/dir1/dir2 > > And then check the smack label of dir1 and dir2. > > # chsmack /data/dir1 > > /data/dir1 access="system" > > # chsmack /data/dir1/dir2 > > /data/dir1/dir2 access="_" > > We can see dir1 did not inherit transmute flag from data and dir2 got the > > process label. > > > > The transmute xattr of the inode is set inside the smack_d_instantiate > > which depends on SMK_INODE_CHANGED bit of isp->smk_flags. But the bit is > > not set in the overlay fs mkdir function call chain. So one simple solution > > we have is passing inode ptr into smack_dentry_create_files_as and set the > > SMK_INODE_CHANGED bit if parent dir is transmuting. Although it looks > > reasonable to me and we did not meet any issue in testing, I am not sure if > > there is a better solution to it. It will be great, if experts could take > > a look. > > I will be happy to look at your solution. Please post a patch. > Sorry, it takes me a while to review and send out the patch. It contains a few files because it breaks kernel API. But the core is only in the change of smack_dentry_create_files_as. If Roberto's patch will work, we can drop it. I posted my concern in that thread. https://lore.kernel.org/all/20230419192516.757220-1-mengcc@xxxxxxxxxx/ > > > > > > Thanks, > > Mengchi Cheng > > >
