Hi Greg,
Thanks for taking a look.
On Sun, Nov 06, 2022 at 12:27:12PM +0100, Greg KH wrote:
On Sun, Nov 06, 2022 at 06:19:39PM +0800, Aaron Lu wrote:
To capture potential programming errors like mistakenly setting Global bit on kernel page table entries, a selftest for meltdown is added.
This selftest is based on https://github.com/IAIK/meltdown. What this test does is to firstly set a predefined string at a random user address and then with pagemap, get the physical address of this string. Finally, try to fetch the data using kernel's directmap address for this physical address to see if user space can use kernel's page table.
As this is based on someone else's code, what happened to the proper credit for them as the author and copyright owner?
Should I list the contributors in the patch header comment section? Something like this:
The original code is contributed by: $ git shortlog -sne --all 24 Michael Schwarz michael.schwarz91@gmail.com 23 Michael Schwarz michael.schwarz@student.tugraz.at 9 Pavel Boldin boldin.pavel@gmail.com 6 Daniel Gruss lava@gruss.cc 3 Daniel Gruss daniel.gruss@iaik.tugraz.at 3 Jared Deckard jdeckard@equityins.net 3 Moritz Lipp github@mlq.me 2 Matteo Croce mcroce@redhat.com 2 Raphael Carvalho raphael.scarv@gmail.com 2 asgh asgh@users.noreply.github.com 1 Eduardo Marques eduardorbmarques@gmail.com 1 Egor Vorontsov sdoregor@sdore.me 1 Jakub Wilk jwilk@jwilk.net 1 Jason Davies jason@jasondavies.com 1 Lukasz Gryglicki lukaszgryglicki@o2.pl 1 Michael Schwarz michael.schwarz@iaik.tugraz.at 1 Raphael S. Carvalho raphaelsc@scylladb.com 1 Steven steven@ceriously.com 1 Vamsi Krishna vamsi3@outlook.com 1 pierwill 19642016+pierwill@users.noreply.github.com 1 ysiyer yegnesh.s.iyer@intel.com
As for copyright, the only copyright I can find in the referenced repo is in the LICENSE file and it is: Copyright (c) 2018 meltdown, I'm not sure if I'm allowed to add copyright statement for others.
Per my tests, this test works well on CPUs that have TSX support. For this reason, this selftest only works on CPUs that supports TSX.
This test requires the knowledge of direct map base. IAIK used the following two methods to get direct map base: 1 through a kernel module to show phys_to_virt(0); 2 by exploiting the same HW vulnerability to guess the base. Method 1 makes running this selftest complex while method 2 is not reliable and I do not want to use a possibly wrong value to run this test. Suggestions are welcome.
Tested on both x86_64 and i386_pae VMs on a host with i7-7700K cpu, success rate is about 50% when nopti kernel cmdline is used.
Signed-off-by: Aaron Lu aaron.lu@intel.com
v2:
- Added [SKIP], [INFO] prefix to some prints;
- Do not run 32bits test on 64bits host since it doesn't make sense to do that;
- Minor comment update.
tools/testing/selftests/x86/Makefile | 2 +- tools/testing/selftests/x86/meltdown.c | 418 +++++++++++++++++++++++++ 2 files changed, 419 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/x86/meltdown.c
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile index 0388c4d60af0..36f99c360a56 100644 --- a/tools/testing/selftests/x86/Makefile +++ b/tools/testing/selftests/x86/Makefile @@ -13,7 +13,7 @@ CAN_BUILD_WITH_NOPIE := $(shell ./check_cc.sh "$(CC)" trivial_program.c -no-pie) TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt test_mremap_vdso \ check_initial_reg_state sigreturn iopl ioperm \ test_vsyscall mov_ss_trap \
syscall_arg_fault fsgsbase_restore sigaltstack
syscall_arg_fault fsgsbase_restore sigaltstack meltdownTARGETS_C_32BIT_ONLY := entry_from_vm86 test_syscall_vdso unwind_vdso \ test_FCMOV test_FCOMI test_FISTTP \ vdso_restorer diff --git a/tools/testing/selftests/x86/meltdown.c b/tools/testing/selftests/x86/meltdown.c new file mode 100644 index 000000000000..8c0c1db49096 --- /dev/null +++ b/tools/testing/selftests/x86/meltdown.c @@ -0,0 +1,418 @@ +// SPDX-License-Identifier: GPL-2.0-only
That's nice but that does NOT reflect the license of the code below, as you state in the comments.
You might want to get an Intel lawyer to look this over and give you advice on how to properly tag this license.
Thanks for the advice.
I've gone through our internal process and was told it is OK to relicense zlib licensed code to GPLv2.
+/*
- This selftest is based on code from https://github.com/IAIK/meltdown
- and can be used to check if user space can read data through kernel
- page table entries.
- Note for i386 test: due to kernel prefer to use high memory for user
- programs, it is necessary to restrict the available memory under that
- of low memory size(around ~896MiB) so that the memory hosting "string"
- in main() is directly mapped.
- Note for both x86_64 and i386 test: the hardware race window can not be
- exploited 100% each time so a single run of the test on a vulnerable system
- may not FAIL. My tests on a i7-7700K cpu have a success rate about 50%.
- The original copyright and license information are shown below:
- Copyright (c) 2018 meltdown
I don't see that copyright in the original github repo, are you sure about that? I see individual developers contributing there instead. Please keep authorship information when you know it.
There is a license file in this repo and I've kept the content intact in the patch, please see this: https://github.com/IAIK/meltdown/blob/master/LICENSE
Thanks, Aaron