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Yafang Shao 399f6185a1 selftests/bpf: Fix selftests broken by mitigations=off 
When we configure the kernel command line with 'mitigations=off' and set
the sysctl knob 'kernel.unprivileged_bpf_disabled' to 0, the commit
bc5bc309db ("bpf: Inherit system settings for CPU security mitigations")
causes issues in the execution of `test_progs -t verifier`. This is
because 'mitigations=off' bypasses Spectre v1 and Spectre v4 protections.

Currently, when a program requests to run in unprivileged mode
(kernel.unprivileged_bpf_disabled = 0), the BPF verifier may prevent
it from running due to the following conditions not being enabled:

  - bypass_spec_v1
  - bypass_spec_v4
  - allow_ptr_leaks
  - allow_uninit_stack

While 'mitigations=off' enables the first two conditions, it does not
enable the latter two. As a result, some test cases in
'test_progs -t verifier' that were expected to fail to run may run
successfully, while others still fail but with different error messages.
This makes it challenging to address them comprehensively.

Moreover, in the future, we may introduce more fine-grained control over
CPU mitigations, such as enabling only bypass_spec_v1 or bypass_spec_v4.

Given the complexity of the situation, rather than fixing each broken test
case individually, it's preferable to skip them when 'mitigations=off' is
in effect and introduce specific test cases for the new 'mitigations=off'
scenario. For instance, we can introduce new BTF declaration tags like
'__failure__nospec', '__failure_nospecv1' and '__failure_nospecv4'.

In this patch, the approach is to simply skip the broken test cases when
'mitigations=off' is enabled. The result of `test_progs -t verifier` as
follows after this commit,

Before this commit
==================

- without 'mitigations=off'
  - kernel.unprivileged_bpf_disabled = 2
    Summary: 74/948 PASSED, 388 SKIPPED, 0 FAILED
  - kernel.unprivileged_bpf_disabled = 0
    Summary: 74/1336 PASSED, 0 SKIPPED, 0 FAILED    <<<<
- with 'mitigations=off'
  - kernel.unprivileged_bpf_disabled = 2
    Summary: 74/948 PASSED, 388 SKIPPED, 0 FAILED
  - kernel.unprivileged_bpf_disabled = 0
    Summary: 63/1276 PASSED, 0 SKIPPED, 11 FAILED   <<<< 11 FAILED

After this commit
=================

- without 'mitigations=off'
  - kernel.unprivileged_bpf_disabled = 2
    Summary: 74/948 PASSED, 388 SKIPPED, 0 FAILED
  - kernel.unprivileged_bpf_disabled = 0
    Summary: 74/1336 PASSED, 0 SKIPPED, 0 FAILED    <<<<
- with this patch, with 'mitigations=off'
  - kernel.unprivileged_bpf_disabled = 2
    Summary: 74/948 PASSED, 388 SKIPPED, 0 FAILED
  - kernel.unprivileged_bpf_disabled = 0
    Summary: 74/948 PASSED, 388 SKIPPED, 0 FAILED   <<<< SKIPPED

Fixes: bc5bc309db ("bpf: Inherit system settings for CPU security mitigations")
Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Closes: https://lore.kernel.org/bpf/CAADnVQKUBJqg+hHtbLeeC2jhoJAWqnmRAzXW3hmUCNSV9kx4sQ@mail.gmail.com
Link: https://lore.kernel.org/bpf/20231025031144.5508-1-laoar.shao@gmail.com
2023-10-26 15:42:03 +02:00
arch bpf-next-for-netdev 2023-10-16 21:05:33 -07:00
block block: fix kernel-doc for disk_force_media_change() 2023-09-26 00:43:34 -06:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: sm2 - Fix crash caused by uninitialized context 2023-09-20 13:10:10 +08:00
Documentation bpf, docs: Define signed modulo as using truncated division 2023-10-19 01:36:12 +02:00
drivers netkit, bpf: Add bpf programmable net device 2023-10-24 16:06:03 -07:00
fs \n 2023-10-11 14:21:15 -07:00
include netkit, bpf: Add bpf programmable net device 2023-10-24 16:06:03 -07:00
init workqueue: Changes for v6.6 2023-09-01 16:06:32 -07:00
io_uring io-wq: fully initialize wqe before calling cpuhp_state_add_instance_nocalls() 2023-10-05 14:11:18 -06:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel bpf: Add more WARN_ON_ONCE checks for mismatched alloc and free 2023-10-26 14:23:33 +02:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-10-05 13:16:47 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/percpu.c: introduce pcpu_alloc_size() 2023-10-20 14:15:06 -07:00
net xsk: Avoid starving the xsk further down the list 2023-10-24 11:55:36 +02:00
rust Documentation work keeps chugging along; stuff for 6.6 includes: 2023-08-30 20:05:42 -07:00
samples samples/bpf: Allow building with custom bpftool 2023-10-26 15:32:13 +02:00
scripts kbuild: remove stale code for 'source' symlink in packaging scripts 2023-10-01 23:06:06 +09:00
security KEYS: trusted: Remove redundant static calls usage 2023-10-10 11:19:43 -07:00
sound ALSA: usb-audio: Fix microphone sound on Nexigo webcam. 2023-10-09 08:20:00 +02:00
tools selftests/bpf: Fix selftests broken by mitigations=off 2023-10-26 15:42:03 +02:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap MAINTAINERS: update Matthieu's email address 2023-10-05 09:34:32 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS netkit, bpf: Add bpf programmable net device 2023-10-24 16:06:03 -07:00
Makefile Linux 6.6-rc5 2023-10-08 13:49:43 -07:00
README

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.