On 12/5/19 7:50 PM, Paul Moore wrote:
On Thu, Dec 5, 2019 at 1:14 PM Paul Moore <paul@xxxxxxxxxxxxxx> wrote:
On Thu, Dec 5, 2019 at 1:10 PM Stephen Smalley <sds@xxxxxxxxxxxxx> wrote:
On 12/5/19 12:41 PM, Paul Moore wrote:
Hmm. I haven't done any debugging yet, but the BPF tests are failing
(they pass with kernel-5.5.0-0.rc0.git5.1.2.secnext.fc32.x86_64):
...
They all pass for me (with your next-queue branch, using the
selinux-testsuite defconfig fragment merged with the Fedora config).
Oh goodie, I'm special :/
FWIW, my current test kernel is the next-queue branch rebased on top
of Linus' current tree, using the latest config from the secnext
kernel builds (Fedora Rawhide + stuff for the test suite).
The error above doesn't look SELinux-related; it looks like your kernel
is rejecting the trivial bpf program used in the test code as being
invalid for some reason.
That's where I'm at as well, I'm building an instrumented kernel right
now to try and track down the source. I'm sure it is something silly
like a messed up kernel config or something, but I'd like to
understand *why*.
I traced the "./bpf_test -p" failure down to a BTF check in the BPF
verifier, there is a comment in that code block which helpfully reads:
"Either gcc or pahole or kernel are broken.".
:/
The relevant commit is 8580ac9404f6 ("bpf: Process in-kernel BTF"),
and it appears to be new for v5.5; it isn't present in selinux/next or
selinux/next-queue. Recompiling with CONFIG_DEBUG_INFO_BTF disabled
does allow "./bpf_test -p" to succeed, but I hit other BPF test
failures further along. For reasons I don't understand, the secnext
kernel builds (which should have this code, and have
CONFIG_DEBUG_INFO_BTF enabled) are not hitting this problem, but that
may be due to differences in the build tools on the two systems
(although they *should* be the same).
Given that we haven't hit -rc1 yet, and everyone else's builds are
working just fine, I'm going to leave this alone for now. Whatever
the problems may be, they definitely don't appear to be SELinux
related.
I re-based next-queue on top of -linus, enabled CONFIG_DEBUG_INFO_BTF,
rebuilt and booted new kernel, did a git clean -fdx in the
selinux-testsuite directory, and built/ran the testsuite; bpf tests
still passed for me. This was on F31.
