On Fri, Jun 9, 2023 at 4:15 PM Miklos Szeredi <miklos@xxxxxxxxxx> wrote: > > On Fri, 9 Jun 2023 at 09:32, Amir Goldstein <amir73il@xxxxxxxxx> wrote: > > > > Miklos, > > > > This is the solution that we discussed for removing FMODE_NONOTIFY > > from overlayfs real files. > > > > My branch [1] has an extra patch for remove FMODE_NONOTIFY, but > > I am still testing the ovl-fsnotify interaction, so we can defer > > that step to later. > > > > I wanted to post this series earlier to give more time for fsdevel > > feedback and if these patches get your blessing and the blessing of > > vfs maintainers, it is probably better that they will go through the > > vfs tree. > > > > I've tested that overlay "fake" path are still shown in /proc/self/maps > > and in the /proc/self/exe and /proc/self/map_files/ symlinks. > > > > The audit and tomoyo use of file_fake_path() is not tested > > (CC maintainers), but they both look like user displayed paths, > > so I assumed they's want to preserve the existing behavior > > (i.e. displaying the fake overlayfs path). > > I did an audit of all ->vm_file and found a couple of missing ones: Wait, but why only ->vm_file? We were under the assumption the fake path is only needed for mapped files, but the list below suggests that it matters to other file operations as well... > > dump_common_audit_data > ima_file_mprotect > common_file_perm (I don't understand the code enough to know whether > it needs fake dentry or not) > aa_file_perm > __file_path_perm > print_bad_pte > file_path > seq_print_user_ip > __mnt_want_write_file > __mnt_drop_write_file > file_dentry_name > > Didn't go into drivers/ and didn't follow indirect calls (e.g. > f_op->fsysnc). I also may have missed something along the way, but my > guess is that I did catch most cases. Wow. So much for 3-4 special cases... Confused by some of the above. Why would we want __mnt_want_write_file on the fake path? We'd already taken __mnt_want_write on overlay and with real file we need __mnt_want_write on the real path. For IMA/LSMs, I'd imagine that like fanotify, they would rather get the real path where the real policy is stored. If some log files end with relative path instead of full fake path it's probably not the worst outcome. Thoughts? Thanks, Amir.
