6.15-stable review patch. If anyone has any objections, please let me know.
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From: Luis Gerhorst luis.gerhorst@fau.de
[ Upstream commit cf15cdc0f0f39a5c6315200808ec3e3995b0c2d2 ]
Currently, __xlated_unpriv and __jited_unpriv do not work because the BPF syscall will overwrite info.jited_prog_len and info.xlated_prog_len with 0 if the process is not bpf_capable(). This bug was not noticed before, because there is no test that actually uses __xlated_unpriv/__jited_unpriv.
To resolve this, simply restore the capabilities earlier (but still after loading the program). Adding this here unconditionally is fine because the function first checks that the capabilities were initialized before attempting to restore them.
This will be important later when we add tests that check whether a speculation barrier was inserted in the correct location.
Signed-off-by: Luis Gerhorst luis.gerhorst@fau.de Fixes: 9c9f73391310 ("selftests/bpf: allow checking xlated programs in verifier_* tests") Fixes: 7d743e4c759c ("selftests/bpf: __jited test tag to check disassembly after jit") Acked-by: Kumar Kartikeya Dwivedi memxor@gmail.com Tested-by: Eduard Zingerman eddyz87@gmail.com Link: https://lore.kernel.org/r/20250501073603.1402960-2-luis.gerhorst@fau.de Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/bpf/test_loader.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/tools/testing/selftests/bpf/test_loader.c b/tools/testing/selftests/bpf/test_loader.c index 49f2fc61061f5..9551d8d5f8f9f 100644 --- a/tools/testing/selftests/bpf/test_loader.c +++ b/tools/testing/selftests/bpf/test_loader.c @@ -1042,6 +1042,14 @@ void run_subtest(struct test_loader *tester, emit_verifier_log(tester->log_buf, false /*force*/); validate_msgs(tester->log_buf, &subspec->expect_msgs, emit_verifier_log);
+ /* Restore capabilities because the kernel will silently ignore requests + * for program info (such as xlated program text) if we are not + * bpf-capable. Also, for some reason test_verifier executes programs + * with all capabilities restored. Do the same here. + */ + if (restore_capabilities(&caps)) + goto tobj_cleanup; + if (subspec->expect_xlated.cnt) { err = get_xlated_program_text(bpf_program__fd(tprog), tester->log_buf, tester->log_buf_sz); @@ -1067,12 +1075,6 @@ void run_subtest(struct test_loader *tester, }
if (should_do_test_run(spec, subspec)) { - /* For some reason test_verifier executes programs - * with all capabilities restored. Do the same here. - */ - if (restore_capabilities(&caps)) - goto tobj_cleanup; - /* Do bpf_map__attach_struct_ops() for each struct_ops map. * This should trigger bpf_struct_ops->reg callback on kernel side. */