Messages in this thread | | | Date | Wed, 1 Jul 2009 15:29:31 -0400 | Subject | Re: [Patch] allow file truncations when both suid and write permissions set | From | Eric Paris <> |
| |
On Wed, Jul 1, 2009 at 3:27 PM, Eric Sandeen<sandeen@redhat.com> wrote: > Eric Sandeen wrote: >> Amerigo Wang wrote: >>> When suid is set and the non-owner user has write permission, >>> any writing into this file should be allowed and suid should be >>> removed after that. >>> >>> However, current kernel only allows writing without truncations, >>> when we do truncations on that file, we get EPERM. This is a bug. > > ... > >> So I think the main problem here is simply that we didn't set >> ATTR_FORCE, right... >> >> Seems a little odd to |= with ret, -then- check if it's non-0. Maybe: >> >> /* Remove suid/sgid on truncate too */ >> - newattrs.ia_valid |= should_remove_suid(dentry); >> + ret = should_remove_suid(dentry); >> + if (ret) >> + newattrs.ia_valid |= (ret | ATTR_FORCE); >> > > On second thought, and after talking w/ eparis, I think this probably > needs a security_inode_killpriv() too... it seems like it might be best > to change file_remove_suid(*file) to dentry_remove_suid(*dentry) and > just call that from do_truncate()? > > -Eric
All of this stuff seems horribly complex.... I'm trying to wrap my head around everything going on here as well....
-Eric (Paris) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |