xen: patch for XSAs: 216, 217, 218, 219, 220, 221, 222, and 224 (xen 4.8)

This commit contains security patches for xen 4.8. The patches
for XSA-216 applied to the kernel are omitted, as they are part of
80e0cda7ff.

XSA-216 Issue Description:

> The block interface response structure has some discontiguous fields.
> Certain backends populate the structure fields of an otherwise
> uninitialized instance of this structure on their stacks, leaking
> data through the (internal or trailing) padding field.

More: https://xenbits.xen.org/xsa/advisory-216.html

XSA-217 Issue Description:

> Domains controlling other domains are permitted to map pages owned by
> the domain being controlled.  If the controlling domain unmaps such a
> page without flushing the TLB, and if soon after the domain being
> controlled transfers this page to another PV domain (via
> GNTTABOP_transfer or, indirectly, XENMEM_exchange), and that third
> domain uses the page as a page table, the controlling domain will have
> write access to a live page table until the applicable TLB entry is
> flushed or evicted.  Note that the domain being controlled is
> necessarily HVM, while the controlling domain is PV.

More: https://xenbits.xen.org/xsa/advisory-217.html

XSA-218 Issue Description:

> We have discovered two bugs in the code unmapping grant references.
>
> * When a grant had been mapped twice by a backend domain, and then
> unmapped by two concurrent unmap calls, the frontend may be informed
> that the page had no further mappings when the first call completed rather
> than when the second call completed.
>
> * A race triggerable by an unprivileged guest could cause a grant
> maptrack entry for grants to be "freed" twice.  The ultimate effect of
> this would be for maptrack entries for a single domain to be re-used.

More: https://xenbits.xen.org/xsa/advisory-218.html

XSA-219 Issue Description:

> When using shadow paging, writes to guest pagetables must be trapped and
> emulated, so the shadows can be suitably adjusted as well.
>
> When emulating the write, Xen maps the guests pagetable(s) to make the final
> adjustment and leave the guest's view of its state consistent.
>
> However, when mapping the frame, Xen drops the page reference before
> performing the write.  This is a race window where the underlying frame can
> change ownership.
>
> One possible attack scenario is for the frame to change ownership and to be
> inserted into a PV guest's pagetables.  At that point, the emulated write will
> be an unaudited modification to the PV pagetables whose value is under guest
> control.

More: https://xenbits.xen.org/xsa/advisory-219.html

XSA-220 Issue Description:

> Memory Protection Extensions (MPX) and Protection Key (PKU) are features in
> newer processors, whose state is intended to be per-thread and context
> switched along with all other XSAVE state.
>
> Xen's vCPU context switch code would save and restore the state only
> if the guest had set the relevant XSTATE enable bits.  However,
> surprisingly, the use of these features is not dependent (PKU) or may
> not be dependent (MPX) on having the relevant XSTATE bits enabled.
>
> VMs which use MPX or PKU, and context switch the state manually rather
> than via XSAVE, will have the state leak between vCPUs (possibly,
> between vCPUs in different guests).  This in turn corrupts state in
> the destination vCPU, and hence may lead to weakened protections
>
> Experimentally, MPX appears not to make any interaction with BND*
> state if BNDCFGS.EN is set but XCR0.BND{CSR,REGS} are clear.  However,
> the SDM is not clear in this case; therefore MPX is included in this
> advisory as a precaution.

More: https://xenbits.xen.org/xsa/advisory-220.html

XSA-221 Issue Description:

> When polling event channels, in general arbitrary port numbers can be
> specified.  Specifically, there is no requirement that a polled event
> channel ports has ever been created.  When the code was generalised
> from an earlier implementation, introducing some intermediate
> pointers, a check should have been made that these intermediate
> pointers are non-NULL.  However, that check was omitted.

More: https://xenbits.xen.org/xsa/advisory-221.html

XSA-222 Issue Description:

> Certain actions require removing pages from a guest's P2M
> (Physical-to-Machine) mapping.  When large pages are in use to map
> guest pages in the 2nd-stage page tables, such a removal operation may
> incur a memory allocation (to replace a large mapping with individual
> smaller ones).  If this allocation fails, these errors are ignored by
> the callers, which would then continue and (for example) free the
> referenced page for reuse.  This leaves the guest with a mapping to a
> page it shouldn't have access to.
>
> The allocation involved comes from a separate pool of memory created
> when the domain is created; under normal operating conditions it never
> fails, but a malicious guest may be able to engineer situations where
> this pool is exhausted.

More: https://xenbits.xen.org/xsa/advisory-222.html

XSA-224 Issue Description:

> We have discovered a number of bugs in the code mapping and unmapping
> grant references.
>
> * If a grant is mapped with both the GNTMAP_device_map and
> GNTMAP_host_map flags, but unmapped only with host_map, the device_map
> portion remains but the page reference counts are lowered as though it
> had been removed. This bug can be leveraged cause a page's reference
> counts and type counts to fall to zero while retaining writeable
> mappings to the page.
>
> * Under some specific conditions, if a grant is mapped with both the
> GNTMAP_device_map and GNTMAP_host_map flags, the operation may not
> grab sufficient type counts.  When the grant is then unmapped, the
> type count will be erroneously reduced.  This bug can be leveraged
> cause a page's reference counts and type counts to fall to zero while
> retaining writeable mappings to the page.
>
> * When a grant reference is given to an MMIO region (as opposed to a
> normal guest page), if the grant is mapped with only the
> GNTMAP_device_map flag set, a mapping is created at host_addr anyway.
> This does *not* cause reference counts to change, but there will be no
> record of this mapping, so it will not be considered when reporting
> whether the grant is still in use.

More: https://xenbits.xen.org/xsa/advisory-224.html

pkgs/applications/virtualization/xen/4.8.nix

@@ -51,10 +51,10 @@ callPackage (import ./generic.nix (rec {
       };
       buildInputs = qemuDeps;
       patches = [
-        #(xsaPatch {
-        #  name = "197-4.5-qemuu";
-        #  sha256 = "09gp980qdlfpfmxy0nk7ncyaa024jnrpzx9gpq2kah21xygy5myx";
-        #})
+        (xsaPatch {
+          name = "216-qemuu";
+          sha256 = "09gp980qdlfpfmxy0nk7ncyaa024jnrpzx9gpq2kah21xygy5ma1";
+        })
       ];
       meta.description = "Xen's fork of upstream Qemu";
     };
@@ -150,6 +150,58 @@ callPackage (import ./generic.nix (rec {
         name = "214";
         sha256 = "0qapzx63z0yl84phnpnglpkxp6b9sy1y7cilhwjhxyigpfnm2rrk";
       })
+      (xsaPatch {
+        name = "217";
+        sha256 = "1khs5ilif14dzcm7lmikjzkwsrfzlmir1rgrgzkc411gf18ylzmj";
+      })
+      (xsaPatch {
+        name = "218-4.8/0001-gnttab-fix-unmap-pin-accounting-race";
+        sha256 = "0r363frai239r2wmwxi48kcr50gbk5l64nja0h9lppi3z2y3dkdd";
+      })
+      (xsaPatch {
+        name = "218-4.8/0002-gnttab-Avoid-potential-double-put-of-maptrack-entry";
+        sha256 = "07wm06i7frv7bsaykakx3g9h0hfqv96zcadvwf6wv194dggq1plc";
+      })
+      (xsaPatch {
+        name = "218-4.8/0003-gnttab-correct-maptrack-table-accesses";
+        sha256 = "0ad0irc3p4dmla8sp3frxbh2qciji1dipkslh0xqvy2hyf9p80y9";
+      })
+      (xsaPatch {
+        name = "219-4.8";
+        sha256 = "16q7kiamy86x8qdvls74wmq5j72kgzgdilryig4q1b21mp0ij1jq";
+      })
+      (xsaPatch {
+        name = "220-4.8";
+        sha256 = "0214qyqx7qap5y1pdi9fm0vz4y2fbyg71gaq36fisknj35dv2mh5";
+      })
+      (xsaPatch {
+        name = "221";
+        sha256 = "1mcr1nqgxyjrkywdg7qhlfwgz7vj2if1dhic425vgd41p9cdgl26";
+      })
+      (xsaPatch {
+        name = "222-1";
+        sha256 = "0x02x4kqwfw255638fh2zcxwig1dy6kadlmqim1jgnjgmrvvqas2";
+      })
+      (xsaPatch {
+        name = "222-2-4.8";
+        sha256 = "1xhyp6q3c5l8djh965g1i8201m2wvhms8k886h4sn30hks38giin";
+      })
+      (xsaPatch {
+        name = "224-4.8/0001-gnttab-Fix-handling-of-dev_bus_addr-during-unmap";
+        sha256 = "1k326yan5811qzyvpdfkv801a19nyd09nsqayi8gyh58xx9c21m4";
+      })
+      (xsaPatch {
+        name = "224-4.8/0002-gnttab-never-create-host-mapping-unless-asked-to";
+        sha256 = "06nj1x59bbx9hrj26xmvbw8z805lfqhld9hm0ld0fs6dmcpqzcck";
+      })
+      (xsaPatch {
+        name = "224-4.8/0003-gnttab-correct-logic-to-get-page-references-during-m";
+        sha256 = "0kmag6fdsskgplcvzqp341yfi6pgc14wvjj58bp7ydb9hdk53qx2";
+      })
+      (xsaPatch {
+        name = "224-4.8/0004-gnttab-__gnttab_unmap_common_complete-is-all-or-noth";
+        sha256 = "1ww80pi7jr4gjpymkcw8qxmr5as18b2asdqv35527nqprylsff9f";
+      })
     ];
 
   # Fix build on Glibc 2.24.