svn commit: r333263 - in head: lib/libjail sys/cddl/contrib/opensolaris/uts/common/fs/zfs sys/compat/linprocfs sys/compat/linsysfs sys/fs/devfs sys/fs/fdescfs sys/fs/nullfs sys/fs/procfs sys/fs/pse...

[James Gritton]

On 2018-11-16 10:34, Alan Somers wrote:

> On Fri, May 4, 2018 at 2:54 PM Jamie Gritton <jamie at freebsd.org> wrote: 
> 
>> Author: jamie
>> Date: Fri May  4 20:54:27 2018
>> New Revision: 333263
>> URL: https://svnweb.freebsd.org/changeset/base/333263
>> 
>> Log:
>> Make it easier for filesystems to count themselves as jail-enabled,
>> by doing most of the work in a new function prison_add_vfs in kern_jail.c
>> Now a jail-enabled filesystem need only mark itself with VFCF_JAIL, and
>> the rest is taken care of.  This includes adding a jail parameter like
>> allow.mount.foofs, and a sysctl like security.jail.mount_foofs_allowed.
>> Both of these used to be a static list of known filesystems, with
>> predefined permission bits.
>> 
>> Reviewed by:  kib
>> Differential Revision:        D14681
>> 
>> Modified:
>> head/lib/libjail/jail.c
>> head/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/zfs_vfsops.c
>> head/sys/compat/linprocfs/linprocfs.c
>> head/sys/compat/linsysfs/linsysfs.c
>> head/sys/fs/devfs/devfs_vfsops.c
>> head/sys/fs/fdescfs/fdesc_vfsops.c
>> head/sys/fs/nullfs/null_vfsops.c
>> head/sys/fs/procfs/procfs.c
>> head/sys/fs/pseudofs/pseudofs.h
>> head/sys/fs/tmpfs/tmpfs_vfsops.c
>> head/sys/kern/kern_jail.c
>> head/sys/kern/vfs_init.c
>> head/sys/kern/vfs_mount.c
>> head/sys/kern/vfs_subr.c
>> head/sys/sys/jail.h
>> head/sys/sys/mount.h
>> head/usr.sbin/jail/jail.8
>> 
>> Modified: head/lib/libjail/jail.c
>> ==============================================================================
>> --- head/lib/libjail/jail.c     Fri May  4 20:38:26 2018        (r333262)
>> +++ head/lib/libjail/jail.c     Fri May  4 20:54:27 2018        (r333263)
>> @@ -1048,7 +1048,13 @@ kldload_param(const char *name)
>> else if (strcmp(name, "sysvmsg") == 0 || strcmp(name, "sysvsem") == 0 ||
>> strcmp(name, "sysvshm") == 0)
>> kl = kldload(name);
>> -       else {
>> +       else if (strncmp(name, "allow.mount.", 12) == 0) {
>> +               /* Load the matching filesystem */
>> +               kl = kldload(name + 12);
>> +               if (kl < 0 && errno == ENOENT &&
>> +                   strncmp(name + 12, "no", 2) == 0)
>> +                       kl = kldload(name + 14);
>> +       } else {
>> errno = ENOENT;
>> return (-1);
>> }
> 
> I'm curious about this part of the change.  Why is it necessary to load the module in the "allow.mount.noXXXfs" case, when the jail is forbidden to mount the filesystem? It seems like that would just load modules that aren't going to be used. 
> 
> Additional discussion at https://github.com/iocage/iocage/issues/689 . 
> 
> -Alan

Presumably such a parameter would be included in some jails in
conjunction with the positive being included in others (perhaps as a
default).  The truth is I never really considered whether the "no"
option would be used, I just always treat these option as pairs. 

It may be reasonable (at least in the allow.mount.* case) to silently
disregard a "no" option that doesn't exist, but I don't know how many
places would need to be modified for that to go smoothly.  Though I
don't expect that there would be too many people who bother to include a
jail parameter about a filesystem which they're not planning to use. 

- Jamie