Re: PATCH: cdrecord: avoiding scsi device numbering for ide devices

David Greaves
2004-08-21T06:58:13Z

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Kyle Moffett wrote:

|
| Security issue:
| Anybody with read access to certain block devices (Like CD-RW

~ ^^^^

| drives.) could reflash the firmware or otherwise turn the drive into a
| rather expensive doorstop.
|
| Chosen solution for 2.6.8.1:
| Only allow certain known-safe commands, anything else needs
| root privileges, specifically CAP_SYS_RAWIO or CAP_SYS_ADMIN,

~ ^^^^^^^^

| (Seems sane, and follows with the general design of the rest of the
| kernel).

Can someone explain why it isn't anyone with _write_ access to the device?
Surely it's better to drop a user into a group or setgid a program?

If I have write access to a device then I can wipe it's media anyway.
Is there something I'm missing?

| Personally, I'd rather have a setuid executable on my system than
| allow anybody in the cdwriters group to reflash my CDROM drive.

OK, you keep the users out of the group and make the progaram setgid
cdwriters.
Then if someone makes a mess of the set[gu]id code you lose your
cdwriter (which would be gone anyway) and not your whole system.

Why force the program to escalate to root?

David
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