Brian Behlendorf d34d4f97a8 snapdir: add 'disabled' value to make .zfs inaccessible ... In some environments, just making the .zfs control dir hidden from sight might not be enough. In particular, the following scenarios might warrant not allowing access at all: - old snapshots with wrong permissions/ownership - old snapshots with exploitable setuid/setgid binaries - old snapshots with sensitive contents Introducing a new 'disabled' value that not only hides the control dir, but prevents access to its contents by returning ENOENT solves all of the above. The new property value takes advantage of 'iuv' semantics ("ignore unknown value") to automatically fall back to the old default value when a pool is accessed by an older version of ZFS that doesn't yet know about 'disabled' semantics. I think that technically the zfs_dirlook change is enough to prevent access, but preventing lookups and dir entries in an already opened .zfs handle might also be a good idea to prevent races when modifying the property at runtime. Add zfs_snapshot_no_setuid parameter to control whether automatically mounted snapshots have the setuid mount option set or not. this could be considered a partial fix for one of the scenarios mentioned in desired. Reviewed-by: Alexander Motin <mav@FreeBSD.org> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de> Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com> Co-authored-by: Fabian Grünbichler <f.gruenbichler@proxmox.com> Closes #3963 Closes #16587		2024-10-02 09:12:02 -07:00
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sys	snapdir: add 'disabled' value to make .zfs inaccessible	2024-10-02 09:12:02 -07:00