From 0ec9552b43b98deb882bf48efd347be4bd7afc9f Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 30 Nov 2017 13:47:55 -0800 Subject: [PATCH] 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 Signed-off-by: Daniel Borkmann --- samples/bpf/bpf_load.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c index 522ca9252d6c..242631aa4ea2 100644 --- a/samples/bpf/bpf_load.c +++ b/samples/bpf/bpf_load.c @@ -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; }