> I presume, then, that a signal handler could be called, but > instead of code getting executed in home space, code would > get executed in primary space instead. If a carefully > crafted signal handler address was created then the code > actually executed could put the user space in root mode ??
Kernel code would get executed with the user registers set up for the signal handler. By taking careful aim with the help of a kernel listing, a malicious user program could have done ugly things. This is fixed in BitKeeper since yesterday, see ChangeSet 1.2091. > I suppose what I am really trying to understand a little better > is how s390 linux works. This is what I'm guessing: > 1) userland runs in home space mode > 2) kernel runs in primary space mode, uses mvcs/mvcp to > copy between kernel and userland > 3) syscall is implemented using the svc instruction > 4) cow is implementing by forcing program interrupt 0x04 > on write Yes, yes, yes and yes. blue skies, Martin Martin Schwidefsky Linux for zSeries Development & Services IBM Deutschland Entwicklung GmbH ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
