Hi all, As the legacy eeprom driver is being phased out, I am reviewing all its use cases to ensure that the at24 driver will be a suitable replacement. One issue I have found is the handling of specific EEPROMs found on the SMBus of some Sony VAIO laptops. The legacy eeprom driver would expose them to user-space, read-only for all users. It would also recognize them as VAIO EEPROMs and would hide some bytes from non-root users because these bytes contain the BIOS password in a lightly encoded form. In order to keep the same level of functionality, we would have to offer the same with the at24 driver. At this time, the user has to instantiate a "24c02" device manually from user-space. By default this device has permissions 600, which is insufficient for users, and dangerous for root, so a quick chmod 444 is needed. Without the password issue, I would just document the procedure and live with it. However in order to protect the password from being read by random users, the driver itself needs to know that it is dealing with a specific type of EEPROM. It seems that we need to introduce a new device flavor to the at24 driver for this purpose. I see that we already have a number of specific flags (AT24_FLAG_SERIAL and AT24_FLAG_MAC) so I suppose we could add something similar for these VAIO EEPROMs. Something like: /* Some Sony VAIO laptops have a 24c02 at 0x57 with product info */ AT24_CHIP_DATA(at24_data_sony_vaio, 2048 / 8, AT24_FLAG_READONLY | AT24_FLAG_IRUGO | AT24_FLAG_SONY_VAIO); Then I suppose it's only a matter of conditionally zeroing a selected range in at24_read() before it returns, to hide the password from non-root users. Before I start implementing the idea above, I would like to know if anyone objects to it, or has a better idea? Thanks, -- Jean Delvare SUSE L3 Support
