Commit 0ec9552b authored Nov 30, 2017 by Yonghong Song Committed by Daniel Borkmann Dec 01, 2017

samples/bpf: add error checking for perf ioctl calls in bpf loader



load_bpf_file() should fail if ioctl with command
PERF_EVENT_IOC_ENABLE and PERF_EVENT_IOC_SET_BPF fails.
When they do fail, proper error messages are printed.

With this change, the below "syscall_tp" run shows that
the maximum number of bpf progs attaching to the same
perf tracepoint is indeed enforced.
  $ ./syscall_tp -i 64
  prog #0: map ids 4 5
  ...
  prog #63: map ids 382 383
  $ ./syscall_tp -i 65
  prog #0: map ids 4 5
  ...
  prog #64: map ids 388 389
  ioctl PERF_EVENT_IOC_SET_BPF failed err Argument list too long

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

parent c8c088ba

samples/bpf/bpf_load.c

+12 −2

Original line number	Diff line number	Diff line
		@@ -193,8 +193,18 @@ static int load_and_attach(const char event, struct bpf_insn prog, int size)
		return -1;
		}
		event_fd[prog_cnt - 1] = efd;
		ioctl(efd, PERF_EVENT_IOC_ENABLE, 0);
		ioctl(efd, PERF_EVENT_IOC_SET_BPF, fd);
		err = ioctl(efd, PERF_EVENT_IOC_ENABLE, 0);
		if (err < 0) {
		printf("ioctl PERF_EVENT_IOC_ENABLE failed err %s\n",
		strerror(errno));
		return -1;
		}
		err = ioctl(efd, PERF_EVENT_IOC_SET_BPF, fd);
		if (err < 0) {
		printf("ioctl PERF_EVENT_IOC_SET_BPF failed err %s\n",
		strerror(errno));
		return -1;
		}

		return 0;
		}