On Sat, Dec 21, 2024 at 7:17 PM Sedat Dilek sedat.dilek@gmail.com wrote:
On Fri, Dec 20, 2024 at 2:39 AM Andrew Cooper andrew.cooper3@citrix.com wrote:
On 20/12/2024 12:27 am, Sedat Dilek wrote:
On Fri, Dec 20, 2024 at 12:26 AM Andrew Cooper andrew.cooper3@citrix.com wrote:
On 19/12/2024 11:10 pm, Sedat Dilek wrote:
On Thu, Dec 19, 2024 at 6:07 PM Sedat Dilek sedat.dilek@gmail.com wrote:
On Thu, Dec 19, 2024 at 5:44 PM Andrew Cooper andrew.cooper3@citrix.com wrote: > On 19/12/2024 4:14 pm, Sedat Dilek wrote: >> Hi, >> >> Linux v6.12.6 will include XEN CVE fixes from mainline. >> >> Here, I use Debian/unstable AMD64 and the SLIM LLVM toolchain 19.1.x >> from kernel.org. >> >> What does it mean in ISSUE DESCRIPTION... >> >> Furthermore, the hypercall page has no provision for Control-flow >> Integrity schemes (e.g. kCFI/CET-IBT/FineIBT), and will simply >> malfunction in such configurations. >> >> ...when someone uses Clang-kCFI? > The hypercall page has functions of the form: > > MOV $x, %eax > VMCALL / VMMCALL / SYSCALL > RET > > There are no ENDBR instructions, and no prologue/epilogue for hash-based > CFI schemes. > > This is because it's code provided by Xen, not code provided by Linux. > > The absence of ENDBR instructions will yield #CP when CET-IBT is active, > and the absence of hash prologue/epilogue lets the function be used in a > type-confused manor that CFI should have caught. > > ~Andrew Thanks for the technical explanation, Andrew.
Hope that helps the folks of "CLANG CONTROL FLOW INTEGRITY SUPPORT".
I am not an active user of XEN in the Linux-kernel but I am willing to test when Linux v6.12.6 is officially released and give feedback.
https://wiki.xenproject.org/wiki/Testing_Xen#Presence_test https://wiki.xenproject.org/wiki/Testing_Xen#Commands_for_presence_testing
# apt install -t unstable xen-utils-4.17 -y
# xl list Name ID Mem VCPUs State Time(s) Domain-0 0 7872 4 r----- 398.2
Some basic tests LGTM - see also attached stuff.
If you have any tests to recommend, let me know.
That itself is good enough as a smoke test. Thankyou for trying it out.
If you want something a bit more thorough, try https://xenbits.xen.org/docs/xtf/ (Xen's self-tests)
Grab and build it, and `./xtf-runner -aqq --host` will run a variety of extra codepaths in dom0, without the effort of making/running full guests.
~Andrew
Run on Debian 6.12.5 and my selfmade 6.12.5 and 6.12.6. All tests lead to a reboot in case of Debian or in my kernels to a shutdown.
Can you recommend a specific test?
Oh, that's distinctly less good.
Start with just "example". It's literally a hello world microkernel, but the symptoms you're seeing is a dom0 crash, so it will likely provoke it.
Do you have serial to the machine? If so, boot Xen with `console=com1 com1=115200,8n1` (or com2, as appropriate).
If not and you've only got a regular screen, boot Xen with `vga=,keep noreboot` (comma is important) which might leave enough information on screen to get an idea of what's going on.
YES
# xl info | grep xen_commandline xen_commandline : placeholder vga=,keep noreboot
Full command line docs at https://xenbits.xen.org/docs/unstable/misc/xen-command-line.html
dileks@iniza:~/src/xtf/git$ sudo ./xtf-runner --list functional xsa | grep xsa-4 test-pv64-xsa-444 test-hvm64-xsa-451 test-hvm64-xsa-454
Is there no xsa-466 test?
No. XSA-466 is really "well don't do that then if it matters".
More generally, not all XSAs are amenable to testing in this way.
~Andrew
On Debian 6.12.6 kernel the TESTS stop with test-hvm64-xsa-454 - machine freezes - hard reboot.
dileks@iniza:~/src/xtf/git$ sudo ./xtf-runner -a --host
root@iniza:/var/log/xen# LC_ALL=C ls -alth | head -20 total 1.7M -rw-r--r-- 1 root adm 1008K Dec 21 19:10 xenstored-access.log drwxr-xr-x 16 root root 4.0K Dec 21 18:59 .. -rw-r--r-- 1 root adm 32 Dec 21 18:58 xenstored.log drwxr-s--- 2 root adm 36K Dec 21 18:58 . -rw-r--r-- 1 root adm 229 Dec 21 18:53 xl-test-hvm64-xsa-317.log -rw-r--r-- 1 root adm 67 Dec 21 18:53 xl-test-hvm64-xsa-454.log -rw-r--r-- 1 root adm 145 Dec 21 18:53 qemu-dm-test-hvm64-xsa-454.log -rw-r--r-- 1 root adm 232 Dec 21 18:53 qemu-dm-test-hvm64-xsa-451.log -rw-r--r-- 1 root adm 211 Dec 21 18:53 xl-test-hvm64-xsa-451.log -rw-r--r-- 1 root adm 232 Dec 21 18:53 xl-test-hvm32pse-xsa-317.log -rw-r--r-- 1 root adm 228 Dec 21 18:53 xl-test-pv64-xsa-444.log -rw-r--r-- 1 root adm 228 Dec 21 18:53 xl-test-pv64-xsa-339.log -rw-r--r-- 1 root adm 228 Dec 21 18:53 xl-test-pv64-xsa-333.log -rw-r--r-- 1 root adm 228 Dec 21 18:53 xl-test-pv64-xsa-317.log -rw-r--r-- 1 root adm 232 Dec 21 18:53 qemu-dm-test-hvm64-xsa-317.log -rw-r--r-- 1 root adm 232 Dec 21 18:53 xl-test-hvm32pae-xsa-317.log -rw-r--r-- 1 root adm 232 Dec 21 18:53 qemu-dm-test-hvm32pse-xsa-317.log -rw-r--r-- 1 root adm 229 Dec 21 18:53 xl-test-hvm32-xsa-317.log -rw-r--r-- 1 root adm 232 Dec 21 18:53 qemu-dm-test-hvm32pae-xsa-317.log
root@iniza:/var/log/xen# cat qemu-dm-test-hvm64-xsa-454.log VNC server running on 127.0.0.1:5900 xen-qemu-system-i386: failed to create 'console' device '0': declining to handle console type 'xenconsoled'
root@iniza:/var/log/xen# cat xl-test-hvm64-xsa-454.log Waiting for domain test-hvm64-xsa-454 (domid 94) to die [pid 4686]
-Sedat-
With...
dileks@iniza:~/src/xtf/git$ mv tests/xsa-454 ../ dileks@iniza:~/src/xtf/git$ mv tests/xsa-consoleio-write ../
Combined test results: test-hvm32-cpuid-faulting SKIP test-hvm32pae-cpuid-faulting SKIP test-hvm32pse-cpuid-faulting SKIP test-hvm64-cpuid-faulting SKIP test-pv64-cpuid-faulting SKIP test-hvm64-fpu-exception-emulation SKIP test-hvm32-invlpg~hap SUCCESS test-hvm32-invlpg~shadow SUCCESS test-hvm32pae-invlpg~hap SUCCESS test-hvm32pae-invlpg~shadow SUCCESS test-hvm64-invlpg~hap SUCCESS test-hvm64-invlpg~shadow SUCCESS test-hvm64-lbr-tsx-vmentry SUCCESS test-hvm32-livepatch-priv-check SUCCESS test-hvm64-livepatch-priv-check SUCCESS test-pv64-livepatch-priv-check SUCCESS test-hvm32-lm-ts SUCCESS test-hvm64-lm-ts SUCCESS test-hvm32pae-memop-seg SUCCESS test-hvm64-memop-seg SUCCESS test-pv64-memop-seg SUCCESS test-hvm32pae-nmi-taskswitch-priv SUCCESS test-pv64-pv-fsgsbase SKIP test-pv64-pv-iopl~hypercall SUCCESS test-pv64-pv-iopl~vmassist SUCCESS test-hvm32-swint-emulation SKIP test-hvm32pae-swint-emulation SKIP test-hvm32pse-swint-emulation SKIP test-hvm64-swint-emulation SKIP test-hvm32-umip SKIP test-hvm64-umip SKIP test-hvm32-xsa-122 SUCCESS test-hvm32pae-xsa-122 SUCCESS test-hvm32pse-xsa-122 SUCCESS test-hvm64-xsa-122 SUCCESS test-pv64-xsa-122 SUCCESS test-hvm32-xsa-123 SKIP test-pv64-xsa-167 SKIP test-hvm64-xsa-168~shadow SUCCESS test-hvm64-xsa-170 SKIP test-hvm64-xsa-173~shadow SUCCESS test-pv64-xsa-182 SUCCESS test-hvm32-xsa-186 SKIP test-hvm64-xsa-186 SKIP test-hvm32-xsa-188 SUCCESS test-hvm32pae-xsa-188 SUCCESS test-hvm32pse-xsa-188 SUCCESS test-hvm64-xsa-188 SUCCESS test-pv64-xsa-188 SUCCESS test-hvm32-xsa-191 SKIP test-hvm32-xsa-192 SUCCESS test-pv64-xsa-193 SUCCESS test-hvm64-xsa-195 SUCCESS test-hvm64-xsa-196 SKIP test-hvm32-xsa-200 SKIP test-hvm32-xsa-203 SKIP test-hvm64-xsa-204 SKIP test-pv64-xsa-212 SUCCESS test-pv64-xsa-213 SUCCESS test-hvm64-xsa-221 SUCCESS test-pv64-xsa-221 SUCCESS test-pv64-xsa-224 SUCCESS test-pv64-xsa-227 SUCCESS test-hvm64-xsa-231 SUCCESS test-pv64-xsa-231 SUCCESS test-hvm64-xsa-232 SUCCESS test-pv64-xsa-232 SUCCESS test-pv64-xsa-234 SUCCESS test-hvm32-xsa-239 SUCCESS test-pv64-xsa-255 SUCCESS test-pv64-xsa-259 SUCCESS test-pv64-xsa-260 SUCCESS test-hvm64-xsa-261 SUCCESS test-pv64-xsa-265 SUCCESS test-hvm64-xsa-269 SUCCESS test-hvm64-xsa-277 SUCCESS test-hvm64-xsa-278 SUCCESS test-pv64-xsa-279 SUCCESS test-pv64-xsa-286 SUCCESS test-pv64-xsa-296 SUCCESS test-pv64-xsa-298 SUCCESS test-hvm64-xsa-304 SUCCESS test-hvm64-xsa-308 SUCCESS test-pv64-xsa-316 SUCCESS test-hvm32-xsa-317 SUCCESS test-hvm32pae-xsa-317 SUCCESS test-hvm32pse-xsa-317 SUCCESS test-hvm64-xsa-317 SUCCESS test-pv64-xsa-317 SUCCESS test-pv64-xsa-333 SUCCESS test-pv64-xsa-339 SUCCESS test-pv64-xsa-444 SKIP test-hvm64-xsa-451 SKIP
-Sedat-