Backport of cos and rhel-sap verifier issues for 3.19/4.5 #86
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There is an unexpected difference betweek kernels compiled with gcc and
clang. The former one doesn't support rcu attributes yet, meaning that
READ_TASK_FIELD_INFO on task->cred produces PTR_TO_BTF_ID. The latter
one does support rcu attribute, and READ_TASK_FIELD_INFO ends up with
PTR_TO_BTF_ID | MEM_RCU | MAYBE_NULL [1]. COS seems to be using clang to
compile the kernel:
# from /boot/config
CONFIG_CC_VERSION_TEXT="Chromium OS 16.0_pre484197_p20230405-r12 clang version 16.0.0
(/var/tmp/portage/sys-devel/llvm-16.0_pre484197_p20230405-r12/work/llvm-16.0_pre484197_p20230405/clang 2916b99182752b1aece8cc4479d8d6a20b5e02da)"
The verifier doesn't like the
null part, and to fix it we need to break a chain of reading and verify
that the cred structure is not null.
[1]: https://lore.kernel.org/bpf/[email protected]/
Along the way silence compiler warnings about task_cred
ovalenti
deleted the
ovalenti/backport_cos_and_rhel-sap_verifier_issues
branch
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Description
Backport of #82
Testing
integration-tests pass with
all-integration-testsset at stackrox/collector#1868