<div dir="ltr"><div><div><div><div><div><div><div><div><div><div><div><div><div><div>Ok, let it be as you decide. But maybe this last argument will change your mind. Imagine a user who has two machines, say, A and B. The machine A has a PFS mounted to /home (or /home/user) and B has a slave mirror of that PFS mounted to /backup/user. If that user wants to update his mirror on B, he must login as root and launch 'hammer mirror-copy /home/user B:/backup/user' which means he must run hammer utility as root and also ssh as root on both machines. Is it 100% secure to have a root access over ssh? Has not ssh any yet unseen bugs? I propose something like that:<br><br></div>On A:<br></div>su (it will be necessary as only root has the right to change permissions)<br></div><root password><br></div>hammer -u user add-perm /home mirror-read<br><br></div>On B:<br></div>su<br></div><root password><br></div>hammer -u user add-perm /backup/home mirror-write<br><br></div>And now the mirror can be updated not only by root, but also by user. As the permissions are set on per-PFS basis, user will not be able to make a mirror of any PFS, but only of his own home. zfs allow/unallow works the same way.<br><br></div>Here is a résumé:<br></div>1) Only root has the right to change permissions.<br></div>2) Only root has the right to make any changes to filesystem, which are not on per-PFS basis (like volume management, upgrading filesystem to a new version).<br></div>3) Permissions a per-PFS.<br><br></div>I attach a proof-of-concept. Apply this patch to DragonFly_RELEASE_4_0. You will be able to set the following permissions: mirror-read, mirror-write, snap-add, snap-del as shown above. Three new commands are added to hammer utility: add-perm, del-perm, show-perm. Let me know, if you are interested.<br><div class="gmail_extra"><br><div class="gmail_quote">2015-10-01 6:56 GMT+03:00 Matthew Dillon <span dir="ltr"><<a href="mailto:dillon@backplane.com" target="_blank">dillon@backplane.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Well, I think its a bit too dangerous to give snapshotting power to the user in this case. The snapshots are managed on a per-PFS basis so the user would be able to interfere with whatever root intended on doing with the capability.<br><br></div>-Matt<br></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Sep 26, 2015 at 7:06 AM, Vasily Postnicov <span dir="ltr"><<a href="mailto:shamaz.mazum@gmail.com" target="_blank">shamaz.mazum@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div><div><div><div><div>Hello. I have noticed, that some ioctls, like HAMMERIOC_GETHISTORY or HAMMERIOC_GET_INFO can be made by any user, and there are some like HAMMERIOC_ADD_SNAPSHOT, which only root can do. I find this somewhat "unfair", because why a user cannot, for example, make a snapshot of his own home directory, if there is a PFS mounted to that directory? I think something like zfs allow/unallow is needed here. Any ideas how I can implement this?<br><br></div>Maybe I should add a new record type to vfs/hammer/hammer_disk.h, say HAMMER_RECTYPE_PERM, and use it in the similar way to HAMMER_RECTYPE_CONFIG, like writing functions similar to hammer_ioc_get/set_config? So when a user calls ioctl() it will be like this in the kernel space:<br><br></div>1) Start a new transactions and initialize a cursor.<br></div>2) setup the cursor. Set cursor.key_beg.rec_type = HAMMER_RECTYPE_PERM;<br></div>3) do hammer_btree_lookup(&cursor);<br></div>4) If lookup succeeded, extract permission info and act accordingly to it.<br><br></div>So what you think? Will it work? Maybe I need to cache the results somehow and do not call hammer_btree_lookup() each time ioctl is called? Or it is already done automatically?<br></div>
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