Messages in this thread | | | From | David Laight <> | Subject | RE: [PATCH 03/26] bpfilter: reject kernel addresses | Date | Thu, 23 Jul 2020 14:42:11 +0000 |
| |
From: Christoph Hellwig > Sent: 23 July 2020 07:09 > > The bpfilter user mode helper processes the optval address using > process_vm_readv. Don't send it kernel addresses fed under > set_fs(KERNEL_DS) as that won't work.
What sort of operations is the bpf filter doing on the sockopt buffers?
Any attempts to reject some requests can be thwarted by a second application thread modifying the buffer after the bpf filter has checked that it allowed.
You can't do security by reading a user buffer twice.
David
- Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
| |