Hi, this is a updated patch series for the mtab translator. I believe I have cleanly addressed all concerns and all issues I encountered while I was testing the translator (I'm dogfooding by the way).
Notable changes: * The correct path is now stored in the peropen struct. The fact that it previously kinda worked was a mere accident. * fsys_get_children now filters the list of active translators according to the credentials of the client. * The translator used to traverse the translator tree and if it encountered itself, it would deadlock. This is cleanly solved by comparing the control ports of the current node and the mtab translator. * The translator has been cleaned up, produces more meaningful mtab files and afaics implements all the necessary libtrivfs bits. Please have a look, I mostly followed the advice in the hello translator (handy regexp there, though I don't understand it, I just used it) and looked at the null translator for reference. Most importantly this version addresses Neals concern about not revealing mount points if the requesting user has no read permissions in the parent directory. The fix is clean and at the RPC level. Richard mentioned that revealing mount points does not seem to be a concern on Linux, but arguably on Hurd an active translator is more common than a mount on linux. With this iteration of the patch it is actually possible to get both the Linux behavior and a privacy enhanced (bling bling) Hurd behavior. If the mtab translator is running as root, it shows all active translators to anyone who accesses it. If the translator is running as a unprivileged user created solely for this purpose, one get's only translators in directories matching S_IROTH. If the translator is run by a regular user, she can see exactly those translators that she could also discover using say ls. However, if she knows a specific path to a translator in a directory that she may not read, she can use the full path as entry point to discover any translators below that node. I have tested that the access checks works as expected using tmpfs and nfs for libdiskfs and libnetfs respectively. For your convenience I've pushed this series to my hurd.git on darnassus in the branch feature-mtab-translator-v3: git://darnassus.sceen.net/teythoon/hurd.git More gory details: [PATCH 01/17] libnetfs: implement file_get_translator_cntl This is needed so that one can get the control port to active translators bound to nodes of libnetfs based translators. I can confirm that binding a tmpfs translator to a node on an nfs translator works as expected. [PATCH 02/17] pfinet: Fix call to kfree_s I found that while playing around with coccinelle. Please have a look. coccinelle is awesome by the way. [PATCH 03/17] libdiskfs: track file name in struct peropen [PATCH 04/17] libnetfs: track file name in struct peropen Properly store the path relative to the translator root. [PATCH 05/17] libfshelp: add translator-list.c fshelp_get_active_translators now takes a callback to filter the list of children to return. [PATCH 06/17] libdiskfs: add fsys_get_children [PATCH 07/17] libnetfs: add fsys_get_children There's a filter function that performs the permission check. Please have a close look at these two, there's locking and reference counting involved. Btw, I think we should make libdiskfs and libnetfs more alike. Now I know that renaming files and identifiers and reorganizing code is an intrusive operation that affects the history of the version control system, but I think in this case this might be worth it. This would let us compare libdiskfs and libnetfs more easily using diff and will most likely reveal opportunities to move common functionality to libfshelp. [PATCH 08/17] libtrivfs: add fsys_get_children [PATCH 09/17] trans/symlink.c: add fsys_get_children [PATCH 10/17] hurd: add fsys_get_children [PATCH 11/17] libdiskfs: add fsys_get_source [PATCH 12/17] libnetfs: add fsys_get_source [PATCH 13/17] libtrivfs: add fsys_get_source [PATCH 14/17] trans/symlink.c: add fsys_get_source [PATCH 15/17] hurd: add fsys_get_source No changes other than stylistic ones. [PATCH 16/17] XXX this looks wrong to me, please have a look Please have a look. I think this cannot work (and it does not work according to my tests). [PATCH 17/17] add mtab prototype Many changes, should be feature complete by now. Cheers, Justus
