This patch set proposes KUnit, a lightweight unit testing and mocking
framework for the Linux kernel.
Unlike Autotest and kselftest, KUnit is a true unit testing framework;
it does not require installing the kernel on a test machine or in a VM
and does not require tests to be written in userspace running on a host
kernel. Additionally, KUnit is fast: From invocation to completion KUnit
can run several dozen tests in under a second. Currently, the entire
KUnit test suite for KUnit runs in under a second from the initial
invocation (build time excluded).
KUnit is heavily inspired by JUnit, Python's unittest.mock, and
Googletest/Googlemock for C++. KUnit provides facilities for defining
unit test cases, grouping related test cases into test suites, providing
common infrastructure for running tests, mocking, spying, and much more.
## What's so special about unit testing?
A unit test is supposed to test a single unit of code in isolation,
hence the name. There should be no dependencies outside the control of
the test; this means no external dependencies, which makes tests orders
of magnitudes faster. Likewise, since there are no external dependencies,
there are no hoops to jump through to run the tests. Additionally, this
makes unit tests deterministic: a failing unit test always indicates a
problem. Finally, because unit tests necessarily have finer granularity,
they are able to test all code paths easily solving the classic problem
of difficulty in exercising error handling code.
## Is KUnit trying to replace other testing frameworks for the kernel?
No. Most existing tests for the Linux kernel are end-to-end tests, which
have their place. A well tested system has lots of unit tests, a
reasonable number of integration tests, and some end-to-end tests. KUnit
is just trying to address the unit test space which is currently not
being addressed.
## More information on KUnit
There is a bunch of documentation near the end of this patch set that
describes how to use KUnit and best practices for writing unit tests.
For convenience I am hosting the compiled docs here:
https://google.github.io/kunit-docs/third_party/kernel/docs/
Additionally for convenience, I have applied these patches to a branch:
https://kunit.googlesource.com/linux/+/kunit/rfc/4.19/v3
The repo may be cloned with:
git clone https://kunit.googlesource.com/linux
This patchset is on the kunit/rfc/4.19/v3 branch.
## Changes Since Last Version
- Changed namespace prefix from `test_*` to `kunit_*` as requested by
Shuah.
- Started converting/cleaning up the device tree unittest to use KUnit.
- Started adding KUnit expectations with custom messages.
--
2.20.0.rc0.387.gc7a69e6b6c-goog
Hi,
Here are patches for making sure the ftracetest testcases
are checkbashisms clean.
This actually needs a patch from Juerg, "selftests/ftrace:
Make the coloring POSIX compliant" to complete the work.
http://lkml.kernel.org/r/20190220161333.28109-1-juergh@canonical.com
(Note that this is still under development)
So as Juerg pointed, recently ftracetest becomes not POSIX
compliant, and such kind of issues happened repeatedly.
To avoid those anymore, I decided to introduce a testcase
which runs checkbasisms on ftracetest and its testcases.
I think this can help us to find out whether it was
written in a way out of POSIX.
Thank you,
---
Masami Hiramatsu (2):
selftests/ftrace: Make a script checkbashisms clean
selftests/ftrace: Add checkbashisms meta-testcase
tools/testing/selftests/ftrace/ftracetest | 1 +
.../ftrace/test.d/kprobe/kprobe_ftrace.tc | 2 +-
.../selftests/ftrace/test.d/selftest/bashisms.tc | 21 ++++++++++++++++++++
3 files changed, 23 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/ftrace/test.d/selftest/bashisms.tc
--
Masami Hiramatsu (Linaro) <mhiramat(a)kernel.org>
Introduce in-kernel headers and other artifacts which are made available
as an archive through proc (/proc/kheaders.txz file). This archive makes
it possible to build kernel modules, run eBPF programs, and other
tracing programs that need to extend the kernel for tracing purposes
without any dependency on the file system having headers and build
artifacts.
On Android and embedded systems, it is common to switch kernels but not
have kernel headers available on the file system. Raw kernel headers
also cannot be copied into the filesystem like they can be on other
distros, due to licensing and other issues. There's no linux-headers
package on Android. Further once a different kernel is booted, any
headers stored on the file system will no longer be useful. By storing
the headers as a compressed archive within the kernel, we can avoid these
issues that have been a hindrance for a long time.
The feature is also buildable as a module just in case the user desires
it not being part of the kernel image. This makes it possible to load
and unload the headers on demand. A tracing program, or a kernel module
builder can load the module, do its operations, and then unload the
module to save kernel memory. The total memory needed is 3.8MB.
The code to read the headers is based on /proc/config.gz code and uses
the same technique to embed the headers.
To build a module, the below steps have been tested on an x86 machine:
modprobe kheaders
rm -rf $HOME/headers
mkdir -p $HOME/headers
tar -xvf /proc/kheaders.txz -C $HOME/headers >/dev/null
cd my-kernel-module
make -C $HOME/headers M=$(pwd) modules
rmmod kheaders
Signed-off-by: Joel Fernandes (Google) <joel(a)joelfernandes.org>
---
Changes since v1:
- removed IKH_EXTRA variable, not needed (Masahiro Yamada)
- small fix ups to selftest
- added target to main Makefile etc
- added MODULE_LICENSE to test module
- made selftest more quiet
Changes since RFC:
Both changes bring size down to 3.8MB:
- use xz for compression
- strip comments except SPDX lines
- Call out the module name in Kconfig
- Also added selftests in second patch to ensure headers are always
working.
Documentation/dontdiff | 1 +
init/Kconfig | 11 ++++++
kernel/.gitignore | 2 ++
kernel/Makefile | 27 ++++++++++++++
kernel/kheaders.c | 74 +++++++++++++++++++++++++++++++++++++++
scripts/gen_ikh_data.sh | 19 ++++++++++
scripts/strip-comments.pl | 8 +++++
7 files changed, 142 insertions(+)
create mode 100644 kernel/kheaders.c
create mode 100755 scripts/gen_ikh_data.sh
create mode 100755 scripts/strip-comments.pl
diff --git a/Documentation/dontdiff b/Documentation/dontdiff
index 2228fcc8e29f..05a2319ee2a2 100644
--- a/Documentation/dontdiff
+++ b/Documentation/dontdiff
@@ -151,6 +151,7 @@ int8.c
kallsyms
kconfig
keywords.c
+kheaders_data.h*
ksym.c*
ksym.h*
kxgettext
diff --git a/init/Kconfig b/init/Kconfig
index c9386a365eea..9fbf4f73d98c 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -563,6 +563,17 @@ config IKCONFIG_PROC
This option enables access to the kernel configuration file
through /proc/config.gz.
+config IKHEADERS_PROC
+ tristate "Enable kernel header artifacts through /proc/kheaders.txz"
+ select BUILD_BIN2C
+ depends on PROC_FS
+ help
+ This option enables access to the kernel header and other artifacts that
+ are generated during the build process. These can be used to build kernel
+ modules, and other in-kernel programs such as those generated by eBPF
+ and systemtap tools. If you build the headers as a module, a module
+ called kheaders.ko is built which can be loaded to get access to them.
+
config LOG_BUF_SHIFT
int "Kernel log buffer size (16 => 64KB, 17 => 128KB)"
range 12 25
diff --git a/kernel/.gitignore b/kernel/.gitignore
index b3097bde4e9c..6acf71acbdcb 100644
--- a/kernel/.gitignore
+++ b/kernel/.gitignore
@@ -3,5 +3,7 @@
#
config_data.h
config_data.gz
+kheaders_data.h
+kheaders_data.txz
timeconst.h
hz.bc
diff --git a/kernel/Makefile b/kernel/Makefile
index 6aa7543bcdb2..1d13a7a6c537 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -70,6 +70,7 @@ obj-$(CONFIG_UTS_NS) += utsname.o
obj-$(CONFIG_USER_NS) += user_namespace.o
obj-$(CONFIG_PID_NS) += pid_namespace.o
obj-$(CONFIG_IKCONFIG) += configs.o
+obj-$(CONFIG_IKHEADERS_PROC) += kheaders.o
obj-$(CONFIG_SMP) += stop_machine.o
obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o
obj-$(CONFIG_AUDIT) += audit.o auditfilter.o
@@ -130,3 +131,29 @@ filechk_ikconfiggz = \
targets += config_data.h
$(obj)/config_data.h: $(obj)/config_data.gz FORCE
$(call filechk,ikconfiggz)
+
+# Build a list of in-kernel headers for building kernel modules
+ikh_file_list := include/
+ikh_file_list += arch/$(ARCH)/Makefile
+ikh_file_list += arch/$(ARCH)/include/
+ikh_file_list += scripts/
+ikh_file_list += Makefile
+ikh_file_list += Module.symvers
+ifeq ($(CONFIG_STACK_VALIDATION), y)
+ikh_file_list += $(objtree)/tools/objtool/objtool
+endif
+
+$(obj)/kheaders.o: $(obj)/kheaders_data.h
+
+targets += kheaders_data.txz
+
+quiet_cmd_genikh = GEN $(obj)/kheaders_data.txz
+cmd_genikh = $(srctree)/scripts/gen_ikh_data.sh $@ $^ >/dev/null 2>&1
+$(obj)/kheaders_data.txz: $(ikh_file_list) FORCE
+ $(call cmd,genikh)
+
+filechk_ikheadersxz = (echo "static const char kernel_headers_data[] __used = KH_MAGIC_START"; cat $< | scripts/bin2c; echo "KH_MAGIC_END;")
+
+targets += kheaders_data.h
+$(obj)/kheaders_data.h: $(obj)/kheaders_data.txz FORCE
+ $(call filechk,ikheadersxz)
diff --git a/kernel/kheaders.c b/kernel/kheaders.c
new file mode 100644
index 000000000000..c39930f51202
--- /dev/null
+++ b/kernel/kheaders.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * kernel/kheaders.c
+ * Provide headers and artifacts needed to build kernel modules.
+ * (Borrowed code from kernel/configs.c)
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/init.h>
+#include <linux/uaccess.h>
+
+/*
+ * Define kernel_headers_data and kernel_headers_data_size, which contains the
+ * compressed kernel headers. The file is first compressed with xz and then
+ * bounded by two eight byte magic numbers to allow extraction from a binary
+ * kernel image:
+ *
+ * IKHD_ST
+ * <image>
+ * IKHD_ED
+ */
+#define KH_MAGIC_START "IKHD_ST"
+#define KH_MAGIC_END "IKHD_ED"
+#include "kheaders_data.h"
+
+
+#define KH_MAGIC_SIZE (sizeof(KH_MAGIC_START) - 1)
+#define kernel_headers_data_size \
+ (sizeof(kernel_headers_data) - 1 - KH_MAGIC_SIZE * 2)
+
+static ssize_t
+ikheaders_read_current(struct file *file, char __user *buf,
+ size_t len, loff_t *offset)
+{
+ return simple_read_from_buffer(buf, len, offset,
+ kernel_headers_data + KH_MAGIC_SIZE,
+ kernel_headers_data_size);
+}
+
+static const struct file_operations ikheaders_file_ops = {
+ .owner = THIS_MODULE,
+ .read = ikheaders_read_current,
+ .llseek = default_llseek,
+};
+
+static int __init ikheaders_init(void)
+{
+ struct proc_dir_entry *entry;
+
+ /* create the current headers file */
+ entry = proc_create("kheaders.txz", S_IFREG | S_IRUGO, NULL,
+ &ikheaders_file_ops);
+ if (!entry)
+ return -ENOMEM;
+
+ proc_set_size(entry, kernel_headers_data_size);
+
+ return 0;
+}
+
+static void __exit ikheaders_cleanup(void)
+{
+ remove_proc_entry("kheaders.txz", NULL);
+}
+
+module_init(ikheaders_init);
+module_exit(ikheaders_cleanup);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Joel Fernandes");
+MODULE_DESCRIPTION("Echo the kernel header artifacts used to build the kernel");
diff --git a/scripts/gen_ikh_data.sh b/scripts/gen_ikh_data.sh
new file mode 100755
index 000000000000..609196b5cea2
--- /dev/null
+++ b/scripts/gen_ikh_data.sh
@@ -0,0 +1,19 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+spath="$(dirname "$(readlink -f "$0")")"
+
+rm -rf $1.tmp
+mkdir $1.tmp
+
+for f in "${@:2}";
+ do find "$f" ! -name "*.c" ! -name "*.o" ! -name "*.cmd" ! -name ".*";
+done | cpio -pd $1.tmp
+
+for f in $(find $1.tmp); do
+ $spath/strip-comments.pl $f
+done
+
+tar -Jcf $1 -C $1.tmp/ . > /dev/null
+
+rm -rf $1.tmp
diff --git a/scripts/strip-comments.pl b/scripts/strip-comments.pl
new file mode 100755
index 000000000000..f8ada87c5802
--- /dev/null
+++ b/scripts/strip-comments.pl
@@ -0,0 +1,8 @@
+#!/usr/bin/perl -pi
+# SPDX-License-Identifier: GPL-2.0
+
+# This script removes /**/ comments from a file, unless such comments
+# contain "SPDX". It is used when building compressed in-kernel headers.
+
+BEGIN {undef $/;}
+s/\/\*((?!SPDX).)*?\*\///smg;
--
2.20.1.791.gb4d0f1c61a-goog
This patch set proposes KUnit, a lightweight unit testing and mocking
framework for the Linux kernel.
Unlike Autotest and kselftest, KUnit is a true unit testing framework;
it does not require installing the kernel on a test machine or in a VM
and does not require tests to be written in userspace running on a host
kernel. Additionally, KUnit is fast: From invocation to completion KUnit
can run several dozen tests in under a second. Currently, the entire
KUnit test suite for KUnit runs in under a second from the initial
invocation (build time excluded).
KUnit is heavily inspired by JUnit, Python's unittest.mock, and
Googletest/Googlemock for C++. KUnit provides facilities for defining
unit test cases, grouping related test cases into test suites, providing
common infrastructure for running tests, mocking, spying, and much more.
## What's so special about unit testing?
A unit test is supposed to test a single unit of code in isolation,
hence the name. There should be no dependencies outside the control of
the test; this means no external dependencies, which makes tests orders
of magnitudes faster. Likewise, since there are no external dependencies,
there are no hoops to jump through to run the tests. Additionally, this
makes unit tests deterministic: a failing unit test always indicates a
problem. Finally, because unit tests necessarily have finer granularity,
they are able to test all code paths easily solving the classic problem
of difficulty in exercising error handling code.
## Is KUnit trying to replace other testing frameworks for the kernel?
No. Most existing tests for the Linux kernel are end-to-end tests, which
have their place. A well tested system has lots of unit tests, a
reasonable number of integration tests, and some end-to-end tests. KUnit
is just trying to address the unit test space which is currently not
being addressed.
## More information on KUnit
There is a bunch of documentation near the end of this patch set that
describes how to use KUnit and best practices for writing unit tests.
For convenience I am hosting the compiled docs here:
https://google.github.io/kunit-docs/third_party/kernel/docs/
Additionally for convenience, I have applied these patches to a branch:
https://kunit.googlesource.com/linux/+/kunit/rfc/5.0-rc5/v4
The repo may be cloned with:
git clone https://kunit.googlesource.com/linux
This patchset is on the kunit/rfc/5.0-rc5/v4 branch.
## Changes Since Last Version
- Got KUnit working on (hypothetically) all architectures (tested on
x86), as per Rob's (and other's) request
- Punting all KUnit features/patches depending on UML for now.
- Broke out UML specific support into arch/um/* as per "[RFC v3 01/19]
kunit: test: add KUnit test runner core", as requested by Luis.
- Added support to kunit_tool to allow it to build kernels in external
directories, as suggested by Kieran.
- Added a UML defconfig, and a config fragment for KUnit as suggested
by Kieran and Luis.
- Cleaned up, and reformatted a bunch of stuff.
--
2.21.0.rc0.258.g878e2cd30e-goog
The kmod.sh script breaks because an array is passed as input
instead of a single element input.This patch takes elements
one at a time and passed as input to the condition statement
which in turn fixes the error.There was an issue which had
the need for passing a single digit to the condition statement
which is fixed using regular expression.
Distribution: Debian GNU/Linux buster/sid
Bash Version: 5.0.0(1)-release
Signed-off-by: Jeffrin Jose T <jeffrin(a)rajagiritech.edu.in>
---
tools/testing/selftests/kmod/kmod.sh | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/kmod/kmod.sh b/tools/testing/selftests/kmod/kmod.sh
index 0a76314b4414..49b273c3646e 100755
--- a/tools/testing/selftests/kmod/kmod.sh
+++ b/tools/testing/selftests/kmod/kmod.sh
@@ -526,9 +526,12 @@ function run_all_tests()
TEST_ID=${i%:*:*}
ENABLED=$(get_test_enabled $TEST_ID)
TEST_COUNT=$(get_test_count $TEST_ID)
- if [[ $ENABLED -eq "1" ]]; then
- test_case $TEST_ID $TEST_COUNT
- fi
+ for j in $ENABLED ; do
+ CHECK=${j#*:*:}
+ if [[ $CHECK -eq "1" ]]; then
+ test_case $TEST_ID $TEST_COUNT
+ fi
+ done
done
}
--
2.20.1
Note: this version will likely trivially conflict with some cleanup
patches I sent to Bjorn. So this is meant for review purposes only.
If there are no objections, I'd like to look at getting it merged in
the next cycle through the NTB tree.
--
Changes in v2:
* Cleaned up the changes in intel_irq_remapping.c to make them
less confusing and add a comment. (Per discussion with Jacob and
Joerg)
* Fixed a nit from Bjorn and collected his Ack
* Added a Kconfig dependancy on CONFIG_PCI_MSI for CONFIG_NTB_MSI
as the Kbuild robot hit a random config that didn't build
without it.
* Worked in a callback for when the MSI descriptor changes so that
the clients can resend the new address and data values to the peer.
On my test system this was never necessary, but there may be
other platforms where this can occur. I tested this by hacking
in a path to rewrite the MSI descriptor when I change the cpu
affinity of an IRQ. There's a bit of uncertainty over the latency
of the change, but without hardware this can acctually occur on
we can't test this. This was the result of a discussion with Dave.
--
This patch series adds optional support for using MSI interrupts instead
of NTB doorbells in ntb_transport. This is desirable seeing doorbells on
current hardware are quite slow and therefore switching to MSI interrupts
provides a significant performance gain. On switchtec hardware, a simple
apples-to-apples comparison shows ntb_netdev/iperf numbers going from
3.88Gb/s to 14.1Gb/s when switching to MSI interrupts.
To do this, a couple changes are required outside of the NTB tree:
1) The IOMMU must know to accept MSI requests from aliased bused numbers
seeing NTB hardware typically sends proxied request IDs through
additional requester IDs. The first patch in this series adds support
for the Intel IOMMU. A quirk to add these aliases for switchtec hardware
was already accepted. See commit ad281ecf1c7d ("PCI: Add DMA alias quirk
for Microsemi Switchtec NTB") for a description of NTB proxy IDs and why
this is necessary.
2) NTB transport (and other clients) may often need more MSI interrupts
than the NTB hardware actually advertises support for. However, seeing
these interrupts will not be triggered by the hardware but through an
NTB memory window, the hardware does not actually need support or need
to know about them. Therefore we add the concept of Virtual MSI
interrupts which are allocated just like any other MSI interrupt but
are not programmed into the hardware's MSI table. This is done in
Patch 2 and then made use of in Patch 3.
The remaining patches in this series add a library for dealing with MSI
interrupts, a test client and finally support in ntb_transport.
The series is based off of v5.0-rc4 and I've tested it on top of a
of the patches I've already sent to the NTB tree (though they are
independent changes). A git repo is available here:
https://github.com/sbates130272/linux-p2pmem/ ntb_transport_msi_v2
Thanks,
Logan
--
Logan Gunthorpe (12):
iommu/vt-d: Implement dma_[un]map_resource()
NTB: ntb_transport: Ensure the destination buffer is mapped for TX DMA
iommu/vt-d: Add helper to set an IRTE to verify only the bus number
iommu/vt-d: Allow interrupts from the entire bus for aliased devices
PCI/MSI: Support allocating virtual MSI interrupts
PCI/switchtec: Add module parameter to request more interrupts
NTB: Introduce functions to calculate multi-port resource index
NTB: Rename ntb.c to support multiple source files in the module
NTB: Introduce MSI library
NTB: Introduce NTB MSI Test Client
NTB: Add ntb_msi_test support to ntb_test
NTB: Add MSI interrupt support to ntb_transport
drivers/iommu/intel-iommu.c | 23 +-
drivers/iommu/intel_irq_remapping.c | 32 +-
drivers/ntb/Kconfig | 11 +
drivers/ntb/Makefile | 3 +
drivers/ntb/{ntb.c => core.c} | 0
drivers/ntb/msi.c | 415 +++++++++++++++++++++++
drivers/ntb/ntb_transport.c | 197 ++++++++++-
drivers/ntb/test/Kconfig | 9 +
drivers/ntb/test/Makefile | 1 +
drivers/ntb/test/ntb_msi_test.c | 433 ++++++++++++++++++++++++
drivers/pci/msi.c | 55 ++-
drivers/pci/switch/switchtec.c | 12 +-
include/linux/msi.h | 8 +
include/linux/ntb.h | 143 ++++++++
include/linux/pci.h | 9 +
tools/testing/selftests/ntb/ntb_test.sh | 54 ++-
16 files changed, 1379 insertions(+), 26 deletions(-)
rename drivers/ntb/{ntb.c => core.c} (100%)
create mode 100644 drivers/ntb/msi.c
create mode 100644 drivers/ntb/test/ntb_msi_test.c
--
2.19.0
The kernel can be configured to require kexec kernel images and kernel
modules are signed. An IMA policy can be specified on the boot command
line or a custom IMA policy loaded requiring the kexec kernel image and
kernel modules be signed. In addition, systems booted in secure boot
mode with the IMA architecture specific policy enabled, require validly
signed kexec kernel images and kernel modules.
There are two methods of signing kernel images and two methods of
signing kernel modules. In addition, there are two syscalls for each.
kernel image: PE signature, IMA signature
kexec syscalls: kexec_load, kexec_file_load
Both the PE and IMA kernel image signature can only be verified when
loaded via the kexec_file_load syscall.
kernel moodule: appended signature, IMA signature
kernel module syscalls: init_module, finit_module
The appended kernel module signature can be verified when the kernel
module is loaded via either syscall. The IMA kernel module signature
can only be verified when the kernel module is loaded via the
finit_module syscall.
The selftests in this patch set verify that only signed kernel images
and kernel modules are loaded as required, based on the kernel config,
the secure boot mode, and the IMA runtime policy.
Loading a kernel image or kernel module requires root privileges. To
run just the IMA selftests: sudo make TARGETS=ima kselftest
Mimi Zohar (5):
selftests/ima: cleanup the kexec selftest
selftests/ima: define a set of common functions
selftests/ima: define common logging functions
selftests/ima: kexec_file_load syscall test
selftests/ima: loading kernel modules
tools/testing/selftests/ima/Makefile | 3 +-
tools/testing/selftests/ima/common_lib.sh | 154 ++++++++++++++++
tools/testing/selftests/ima/test_kernel_module.sh | 96 ++++++++++
.../testing/selftests/ima/test_kexec_file_load.sh | 195 +++++++++++++++++++++
tools/testing/selftests/ima/test_kexec_load.sh | 53 ++----
5 files changed, 463 insertions(+), 38 deletions(-)
create mode 100755 tools/testing/selftests/ima/common_lib.sh
create mode 100755 tools/testing/selftests/ima/test_kernel_module.sh
create mode 100755 tools/testing/selftests/ima/test_kexec_file_load.sh
--
2.7.5
This patchset is meant to be merged together with "arm64 relaxed ABI" [1].
arm64 has a feature called Top Byte Ignore, which allows to embed pointer
tags into the top byte of each pointer. Userspace programs (such as
HWASan, a memory debugging tool [2]) might use this feature and pass
tagged user pointers to the kernel through syscalls or other interfaces.
Right now the kernel is already able to handle user faults with tagged
pointers, due to these patches:
1. 81cddd65 ("arm64: traps: fix userspace cache maintenance emulation on a
tagged pointer")
2. 7dcd9dd8 ("arm64: hw_breakpoint: fix watchpoint matching for tagged
pointers")
3. 276e9327 ("arm64: entry: improve data abort handling of tagged
pointers")
This patchset extends tagged pointer support to syscall arguments.
For non-memory syscalls this is done by untaging user pointers when the
kernel performs pointer checking to find out whether the pointer comes
from userspace (most notably in access_ok). The untagging is done only
when the pointer is being checked, the tag is preserved as the pointer
makes its way through the kernel.
Since memory syscalls (mmap, mprotect, etc.) don't do memory accesses but
rather deal with memory ranges, untagged pointers are better suited to
describe memory ranges internally. Thus for memory syscalls we untag
pointers completely when they enter the kernel.
One of the alternative approaches to untagging that was considered is to
completely strip the pointer tag as the pointer enters the kernel with
some kind of a syscall wrapper, but that won't work with the countless
number of different ioctl calls. With this approach we would need a custom
wrapper for each ioctl variation, which doesn't seem practical.
The following testing approaches has been taken to find potential issues
with user pointer untagging:
1. Static testing (with sparse [3] and separately with a custom static
analyzer based on Clang) to track casts of __user pointers to integer
types to find places where untagging needs to be done.
2. Static testing with grep to find parts of the kernel that call
find_vma() (and other similar functions) or directly compare against
vm_start/vm_end fields of vma.
3. Static testing with grep to find parts of the kernel that compare
user pointers with TASK_SIZE or other similar consts and macros.
4. Dynamic testing: adding BUG_ON(has_tag(addr)) to find_vma() and running
a modified syzkaller version that passes tagged pointers to the kernel.
Based on the results of the testing the requried patches have been added
to the patchset.
This patchset has been merged into the Pixel 2 kernel tree and is now
being used to enable testing of Pixel 2 phones with HWASan.
This patchset is a prerequisite for ARM's memory tagging hardware feature
support [4].
Thanks!
[1] https://lkml.org/lkml/2018/12/10/402
[2] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html
[3] https://github.com/lucvoo/sparse-dev/commit/5f960cb10f56ec2017c128ef9d16060…
[4] https://community.arm.com/processors/b/blog/posts/arm-a-profile-architectur…
Changes in v10:
- Added "mm, arm64: untag user pointers passed to memory syscalls" back.
- New patch "fs, arm64: untag user pointers in fs/userfaultfd.c".
- New patch "net, arm64: untag user pointers in tcp_zerocopy_receive".
- New patch "kernel, arm64: untag user pointers in prctl_set_mm*".
- New patch "tracing, arm64: untag user pointers in seq_print_user_ip".
Changes in v9:
- Rebased onto 4.20-rc6.
- Used u64 instead of __u64 in type casts in the untagged_addr macro for
arm64.
- Added braces around (addr) in the untagged_addr macro for other arches.
Changes in v8:
- Rebased onto 65102238 (4.20-rc1).
- Added a note to the cover letter on why syscall wrappers/shims that untag
user pointers won't work.
- Added a note to the cover letter that this patchset has been merged into
the Pixel 2 kernel tree.
- Documentation fixes, in particular added a list of syscalls that don't
support tagged user pointers.
Changes in v7:
- Rebased onto 17b57b18 (4.19-rc6).
- Dropped the "arm64: untag user address in __do_user_fault" patch, since
the existing patches already handle user faults properly.
- Dropped the "usb, arm64: untag user addresses in devio" patch, since the
passed pointer must come from a vma and therefore be untagged.
- Dropped the "arm64: annotate user pointers casts detected by sparse"
patch (see the discussion to the replies of the v6 of this patchset).
- Added more context to the cover letter.
- Updated Documentation/arm64/tagged-pointers.txt.
Changes in v6:
- Added annotations for user pointer casts found by sparse.
- Rebased onto 050cdc6c (4.19-rc1+).
Changes in v5:
- Added 3 new patches that add untagging to places found with static
analysis.
- Rebased onto 44c929e1 (4.18-rc8).
Changes in v4:
- Added a selftest for checking that passing tagged pointers to the
kernel succeeds.
- Rebased onto 81e97f013 (4.18-rc1+).
Changes in v3:
- Rebased onto e5c51f30 (4.17-rc6+).
- Added linux-arch@ to the list of recipients.
Changes in v2:
- Rebased onto 2d618bdf (4.17-rc3+).
- Removed excessive untagging in gup.c.
- Removed untagging pointers returned from __uaccess_mask_ptr.
Changes in v1:
- Rebased onto 4.17-rc1.
Changes in RFC v2:
- Added "#ifndef untagged_addr..." fallback in linux/uaccess.h instead of
defining it for each arch individually.
- Updated Documentation/arm64/tagged-pointers.txt.
- Dropped "mm, arm64: untag user addresses in memory syscalls".
- Rebased onto 3eb2ce82 (4.16-rc7).
Reviewed-by: Luc Van Oostenryck <luc.vanoostenryck(a)gmail.com>
Signed-off-by: Andrey Konovalov <andreyknvl(a)google.com>
Andrey Konovalov (12):
uaccess: add untagged_addr definition for other arches
arm64: untag user pointers in access_ok and __uaccess_mask_ptr
lib, arm64: untag user pointers in strn*_user
mm, arm64: untag user pointers passed to memory syscalls
mm, arm64: untag user pointers in mm/gup.c
fs, arm64: untag user pointers in copy_mount_options
fs, arm64: untag user pointers in fs/userfaultfd.c
net, arm64: untag user pointers in tcp_zerocopy_receive
kernel, arm64: untag user pointers in prctl_set_mm*
tracing, arm64: untag user pointers in seq_print_user_ip
arm64: update Documentation/arm64/tagged-pointers.txt
selftests, arm64: add a selftest for passing tagged pointers to kernel
Documentation/arm64/tagged-pointers.txt | 25 +++++++++++--------
arch/arm64/include/asm/uaccess.h | 10 +++++---
fs/namespace.c | 2 +-
fs/userfaultfd.c | 5 ++++
include/linux/memory.h | 4 +++
ipc/shm.c | 2 ++
kernel/sys.c | 14 +++++++++++
kernel/trace/trace_output.c | 2 +-
lib/strncpy_from_user.c | 2 ++
lib/strnlen_user.c | 2 ++
mm/gup.c | 4 +++
mm/madvise.c | 2 ++
mm/mempolicy.c | 5 ++++
mm/migrate.c | 1 +
mm/mincore.c | 2 ++
mm/mlock.c | 5 ++++
mm/mmap.c | 7 ++++++
mm/mprotect.c | 2 ++
mm/mremap.c | 2 ++
mm/msync.c | 2 ++
net/ipv4/tcp.c | 2 ++
tools/testing/selftests/arm64/.gitignore | 1 +
tools/testing/selftests/arm64/Makefile | 11 ++++++++
.../testing/selftests/arm64/run_tags_test.sh | 12 +++++++++
tools/testing/selftests/arm64/tags_test.c | 19 ++++++++++++++
25 files changed, 129 insertions(+), 16 deletions(-)
create mode 100644 tools/testing/selftests/arm64/.gitignore
create mode 100644 tools/testing/selftests/arm64/Makefile
create mode 100755 tools/testing/selftests/arm64/run_tags_test.sh
create mode 100644 tools/testing/selftests/arm64/tags_test.c
--
2.21.0.rc0.258.g878e2cd30e-goog