Hi! On 22:59 Thu 31 Jul , Thomas Petazzoni wrote: > Le Wed, 30 Jul 2008 17:21:31 -0700, > Greg KH <greg@xxxxxxxxx> a ??crit : > > > That's a fault of the hardware, nothing the os can do about that, > > sorry. > > Yes, however some recent chips provide an IOMMU, ??a memory management > unit (MMU) that connects a DMA-capable I/O bus to the main memory??. And > one of its advantage is: > > ?? > Memory protection from malicious or misbehaving devices: a device > cannot read or write to memory that hasn't been explicitly allocated > (mapped) for it. The memory protection is based on the fact that OS > running on the CPU (see figure) exclusively controls both the MMU and > the IOMMU. The devices are physically unable to circumvent or corrupt > configured memory management tables. > ?? There is more that this thing can do. e.g. You can DMA every memory address via firewire. If you connect 2 PCs via firewire they can read/write into each others memory. There are exploits in the internet which allow you to abuse this to bypass the login of other PCs. -Michi -- programing a layer 3+4 network protocol for mesh networks see http://michaelblizek.twilightparadox.com -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
