This makes make-disk-image.nix slightly more consistent with other image
builders we have. Unfortunately I duplicated some code in doing so, but
this is temporary duplication on the path to consolidating everything.
See https://github.com/NixOS/nixpkgs/issues/23052 for more details on that.
I'm also exposing the option in the amazon-image.nix maintainer module.
XSA-197 Issue Description:
> The compiler can emit optimizations in qemu which can lead to double
> fetch vulnerabilities. Specifically data on the rings shared
> between qemu and the hypervisor (which the guest under control can
> obtain mappings of) can be fetched twice (during which time the
> guest can alter the contents) possibly leading to arbitrary code
> execution in qemu.
More: https://xenbits.xen.org/xsa/advisory-197.html
XSA-199 Issue Description:
> The code in qemu which implements ioport read/write looks up the
> specified ioport address in a dispatch table. The argument to the
> dispatch function is a uint32_t, and is used without a range check,
> even though the table has entries for only 2^16 ioports.
>
> When qemu is used as a standalone emulator, ioport accesses are
> generated only from cpu instructions emulated by qemu, and are
> therefore necessarily 16-bit, so there is no vulnerability.
>
> When qemu is used as a device model within Xen, io requests are
> generated by the hypervisor and read by qemu from a shared ring. The
> entries in this ring use a common structure, including a 64-bit
> address field, for various accesses, including ioport addresses.
>
> Xen will write only 16-bit address ioport accesses. However,
> depending on the Xen and qemu version, the ring may be writeable by
> the guest. If so, the guest can generate out-of-range ioport
> accesses, resulting in wild pointer accesses within qemu.
More: https://xenbits.xen.org/xsa/advisory-199.html
XSA-207 Issue Description:
> Certain internal state is set up, during domain construction, in
> preparation for possible pass-through device assignment. On ARM and
> AMD V-i hardware this setup includes memory allocation. On guest
> teardown, cleanup was erroneously only performed when the guest
> actually had a pass-through device assigned.
More: https://xenbits.xen.org/xsa/advisory-207.html
XSA-209 Issue Description:
> When doing bitblt copy backwards, qemu should negate the blit width.
> This avoids an oob access before the start of video memory.
More: https://xenbits.xen.org/xsa/advisory-208.html
XSA-208 Issue Description:
> In CIRRUS_BLTMODE_MEMSYSSRC mode the bitblit copy routine
> cirrus_bitblt_cputovideo fails to check wethehr the specified memory
> region is safe.
More: https://xenbits.xen.org/xsa/advisory-209.html
* vim_configurable: Add packages option to vimrcConfig
Version 8 of vim adds the concept of "vim packages": directories which
contain one or more vim plugins, in either "start" or "opt"
subdirectories. Those in "start" are to be loaded automatically, while
those in "opt" can be loaded manually. Vim detects any packages located
in one of its "packpaths".
The packages option takes a set of sets describing one or more vim
packages, and adds the derivation containing these packages to the
packpath.
* fix documentation.
