On Fri, Aug 17, 2018 at 07:11:12PM +0800, Kinglong Mee wrote: > Hi Niels, > > On 2018/8/17 18:14, Niels de Vos wrote: > > On Fri, Aug 17, 2018 at 05:22:17PM +0800, Kinglong Mee wrote: > >> Hi Niels, > >> > >> On 2018/8/17 17:13, Niels de Vos wrote: > >>> On Fri, Aug 17, 2018 at 03:04:43PM +0800, Kinglong Mee wrote: > >>>> Hello folks, > >>>> > >>>> nfs-ganesha using the new gfapi named glfs_h_acl_set/glfs_h_acl_get, > >>>> at xlator posix, glusterfsd calls acl_get_file/acl_set_file (libacl > >>>> functions) to process xattrs. > >>>> > >>>> By default, sys_lsetxattr/sys_llistxattr/sys_lgetxattr/sys_lremovexattr > >>>> are used to process xattrs. > >>>> But, unfortunately, those two functions do syscall by getxattr/setxattr. > >>>> I don't think that is we want. > >>>> > >>>> Is it a known problem ? > >>> > >>> There should not be a problem for libacl to use syscalls directly. The > >>> Gluster sources use sys_<syscall> so that there can be wrappers for the > >>> differences between OS's. In the end, these sys_<syscall> functions will > >>> mostly call the <syscall> with (adapted) arguments. > >>> > >>> I do not know what problem you are facing, but I can imagine that there > >>> is a 'getxattr' symbol in the executable image that gets called by > >>> libacl, instead of the 'getxattr' syscall. This will likely result in > >>> very strange behaviour, if not segfaults. > >> > >> Sorry for my unclear description. > >> The real problem here is libacl gets/sets xattrs by getxattr/setxattr > >> which follow symbolic links, > >> but, posix xlator get/set xattrs by sys_l*xattr which do not follow > >> symbolic links. > > > > Permission checking is done by the kernel. I do not think setting ACLs > > on a symlink makes much sense. More liberal permissions on the symlink > > will not help with accessing the contents, and restricting permissions > > on a symlink still give the user to access the contents through its real > > filename. > > > > Is there a reason that having ACLs on a symlink can have benefits? > > Sorry, i don't know. > > Md-cache supports caching GF_POSIX_ACL_ACCESS/GF_POSIX_ACL_DEFAULT right now, > but posix_xattr_fill (call _posix_xattr_get_set) does not fill those two > xattrs. > > After I adds the posix_pacl_get to _posix_xattr_get_set, > there are some problems for symlink files. > So that, I find the different between acl_get_file and > sys_llistxattr/sys_lgetxattr.
Because (Linux) filesystems do not have ACLs on symlinks, I think md-cache should also not fetch/cache ACLs on symlinks. Poornima, do you have an opinion about this? Niels _______________________________________________ Gluster-devel mailing list Gluster-devel@gluster.org https://lists.gluster.org/mailman/listinfo/gluster-devel
