Messages in this thread | | | Date | Tue, 6 Mar 2018 20:42:19 +0300 | From | Alexey Dobriyan <> | Subject | Re: + mm-relax-ptrace-mode-in-process_vm_readv2.patch added to -mm tree |
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On Mon, Mar 05, 2018 at 05:02:08PM -0800, Kees Cook wrote: > On Mon, Mar 5, 2018 at 4:07 PM, <akpm@linux-foundation.org> wrote:
> > It is more natural to check for read-from-memory permissions in case of > > process_vm_readv() as PTRACE_MODE_ATTACH is equivalent to write > > permissions. > > NAK, this weakens the existing permission model for reading
What if existing permission model is overezealous?
/proc/*/auxv, /proc/*/environ, /proc*/cmdline, /proc/*/mem opened for reading and process_vm_readv(2) should do PTRACE_MODE_READ and everything else should do PTRACE_MODE_ATTACH.
> cross-process memory. ptrace-readable memory can only be done with > ATTACH, and /proc/$pid/mem also requires ATTACH: > > static int mem_open(struct inode *inode, struct file *file) > { > int ret = __mem_open(inode, file, PTRACE_MODE_ATTACH); > > Only auxv and environ use READ. We should absolutely not create a pass > to a lower permission requirement here.
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