2019-05-29 16:03 UTC+0200 ~ Daniel Borkmann <daniel@xxxxxxxxxxxxx> > On 05/29/2019 11:23 AM, Quentin Monnet wrote: >> There are two functions in libbpf that support passing a log_level >> parameter for the verifier for loading programs: >> bpf_object__load_xattr() and bpf_load_program_xattr(). Both accept an >> attribute object containing the log_level, and apply it to the programs >> to load. >> >> It turns out that to effectively load the programs, the latter function >> eventually relies on the former. This was not taken into account when >> adding support for log_level in bpf_object__load_xattr(), and the >> log_level passed to bpf_load_program_xattr() later gets overwritten with >> a zero value, thus disabling verifier logs for the program in all cases: >> >> bpf_load_program_xattr() // prog.log_level = N; > > I'm confused with your commit message. How can bpf_load_program_xattr() > make sense here, this is the one doing the bpf syscall. Do you mean to > say bpf_prog_load_xattr()? Because this one sets prog->log_level = attr->log_level > and calls bpf_object__load() which in turn does bpf_object__load_xattr() > with an attr that has attr->log_level of 0 such that bpf_object__load_progs() > then overrides it. Unless I'm not missing something, please fix up this > description properly and resubmit. Ugh. Yeah, I mixed up bpf_load_program_xattr() and bpf_prog_load_xattr() in the log, should be bpf_prog_load_xattr() everywhere instead, just as you say. Apologies, I'll fix and resubmit. Thanks, Quentin
