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Constant PATH_MAX is used in function unpriv_helpers.c:open_config().
This constant is provided by include file <limits.h>.
The dependency was added by commit [1], which does not include
<limits.h> directly, relying instead on <limits.h> being included from
zlib.h -> zconf.h.
As it turns out, this is not the case for all systems, e.g. on
Fedora 41 zlib 1.3.1 is used, and there <limits.h> is not included
from zconf.h. Hence, there is a compilation error on Fedora 41.
[1] commit fc2915bb8bfc ("selftests/bpf: More precise cpu_mitigations state detection")
Fixes: fc2915bb8bfc ("selftests/bpf: More precise cpu_mitigations state detection")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Viktor Malik <vmalik@redhat.com>
Link: https://lore.kernel.org/r/20250618093134.3078870-1-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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test_progs and test_verifier binaries execute unpriv tests under the
following conditions:
- unpriv BPF is enabled;
- CPU mitigations are enabled (see [1] for details).
The detection of the "mitigations enabled" state is performed by
unpriv_helpers.c:get_mitigations_off() via inspecting kernel boot
command line, looking for a parameter "mitigations=off".
Such detection scheme won't work for certain configurations,
e.g. when CONFIG_CPU_MITIGATIONS is disabled and boot parameter is
not supplied.
Miss-detection leads to test_progs executing tests meant to be run
only with mitigations enabled, e.g.
verifier_and.c:known_subreg_with_unknown_reg(), and reporting false
failures.
Internally, verifier sets bpf_verifier_env->bypass_spec_{v1,v4}
basing on the value returned by kernel/cpu.c:cpu_mitigations_off().
This function is backed by a variable kernel/cpu.c:cpu_mitigations.
This state is not fully introspect-able via sysfs. The closest proxy
is /sys/devices/system/cpu/vulnerabilities/spectre_v1, but it reports
"vulnerable" state only if mitigations are disabled *and* current cpu
is vulnerable, while verifier does not check cpu state.
There are only two ways the kernel/cpu.c:cpu_mitigations can be set:
- via boot parameter;
- via CONFIG_CPU_MITIGATIONS option.
This commit updates unpriv_helpers.c:get_mitigations_off() to scan
/boot/config-$(uname -r) and /proc/config.gz for
CONFIG_CPU_MITIGATIONS value in addition to boot command line check.
Tested using the following configurations:
- mitigations enabled (unpriv tests are enabled)
- mitigations disabled via boot cmdline (unpriv tests skipped)
- mitigations disabled via CONFIG_CPU_MITIGATIONS
(unpriv tests skipped)
[1] https://lore.kernel.org/bpf/20231025031144.5508-1-laoar.shao@gmail.com/
Reported-by: Mykyta Yatsenko <mykyta.yatsenko5@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250617005710.1066165-2-eddyz87@gmail.com
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The addition of general support for unprivileged tests in test_loader.c
breaks building test_verifier on non-glibc (e.g. musl) systems, due to the
inclusion of glibc extension '<error.h>' in 'unpriv_helpers.c'. However,
the header is actually not needed, so remove it to restore building.
Similarly for sk_lookup.c and flow_dissector.c, error.h is not necessary
and causes problems, so drop them.
Fixes: 1d56ade032a4 ("selftests/bpf: Unprivileged tests for test_loader.c")
Fixes: 0ab5539f8584 ("selftests/bpf: Tests for BPF_SK_LOOKUP attach point")
Fixes: 0905beec9f52 ("selftests/bpf: run flow dissector tests in skb-less mode")
Signed-off-by: Tony Ambardar <tony.ambardar@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/5664367edf5fea4f3f4b4aec3b182bcfc6edff9c.1721713597.git.tony.ambardar@gmail.com
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When we configure the kernel command line with 'mitigations=off' and set
the sysctl knob 'kernel.unprivileged_bpf_disabled' to 0, the commit
bc5bc309db45 ("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: bc5bc309db45 ("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
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Extends test_loader.c:test_loader__run_subtests() by allowing to
execute tests in unprivileged mode, similar to test_verifier.c.
Adds the following new attributes controlling test_loader behavior:
__msg_unpriv
__success_unpriv
__failure_unpriv
* If any of these attributes is present the test would be loaded in
unprivileged mode.
* If only "privileged" attributes are present the test would be loaded
only in privileged mode.
* If both "privileged" and "unprivileged" attributes are present the
test would be loaded in both modes.
* If test has to be executed in both modes, __msg(text) is specified
and __msg_unpriv is not specified the behavior is the same as if
__msg_unpriv(text) is specified.
* For test filtering purposes the name of the program loaded in
unprivileged mode is derived from the usual program name by adding
`@unpriv' suffix.
Also adds attribute '__description'. This attribute specifies text to
be used instead of a program name for display and filtering purposes.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230325025524.144043-4-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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