This patch set follows recent changes that added btf_decl_tag-based argument
annotation support for global subprogs. This time we add ability to pass
PTR_TO_BTF_ID (BTF-aware kernel pointers) arguments into global subprograms.
We support explicitly trusted arguments only, for now.
First three patches are preparatory. Patches #1 and #3 does post-BPF token
code adjustments, to undo merge conflict avoidance measures. Patch #2 makes
PERF_EVENT type enforcement logic aligned with kernel-side logic.
Patch #4 adds logic for arg:trusted tag support on the verifier side. Default
semantic of such arguments is non-NULL, enforced on caller side. But patch #5
adds arg:maybe_null tag that can be combined with arg:trusted to make callee
explicitly do the NULL check, which helps implement "optional" PTR_TO_BTF_ID
arguments.
Patch #6 adds libbpf-side __arg_trusted and __arg_maybe_null macros. Patch #7
adds a bunch of tests validating __arg_trusted in combination with
__arg_maybe_null.
v1->v2:
- added fix up to type enforcement changes, landed earlier;
- dropped bpf_core_cast() changes, will post them separately, as they now
are not used in added tests;
- dropped arg:untrusted support (Alexei);
- renamed arg:nullable to arg:maybe_null (Alexei);
- and also added task_struct___local flavor tests (Alexei).
Andrii Nakryiko (7):
libbpf: integrate __arg_ctx feature detector into kernel_supports()
libbpf: fix __arg_ctx type enforcement for perf_event programs
bpf: move arg:ctx type enforcement check inside the main logic loop
bpf: add __arg_trusted global func arg tag
bpf: add arg:maybe_null tag to be combined with trusted pointers
libbpf: add __arg_trusted and __arg_maybe_null tag macros
selftests/bpf: add trusted global subprog arg tests
include/linux/bpf_verifier.h | 1 +
kernel/bpf/btf.c | 130 +++++++++++----
kernel/bpf/verifier.c | 24 +++
tools/lib/bpf/bpf_helpers.h | 2 +
tools/lib/bpf/features.c | 58 +++++++
tools/lib/bpf/libbpf.c | 86 +++-------
tools/lib/bpf/libbpf_internal.h | 2 +
.../selftests/bpf/prog_tests/verifier.c | 2 +
.../bpf/progs/verifier_global_ptr_args.c | 156 ++++++++++++++++++
9 files changed, 366 insertions(+), 95 deletions(-)
create mode 100644 tools/testing/selftests/bpf/progs/verifier_global_ptr_args.c
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2.34.1
