RE: [PATCH 03/26] bpfilter: reject kernel addresses
David Laight <[email protected]>
| Newsgroups | org.kernel.vger.dccp,dev.linux.lists.bridge,dev.linux.lists.mptcp,org.kernel.vger.bpf,org.kernel.vger.linux-bluetooth,org.kernel.vger.linux-can,org.kernel.vger.linux-crypto,org.kernel.vger.linux-hams,org.kernel.vger.linux-kernel,org.kernel.vger.linux-s390,org.kernel.vger.linux-sctp,org.kernel.vger.linux-wpan,org.kernel.vger.linux-x25,org.kernel.vger.lvs-devel,org.kernel.vger.netdev,org.kernel.vger.netfilter-devel |
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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)