From 4f33ddb4e3e28ade924fbf05ec8bcd7d5c022fee Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= Date: Sat, 9 Nov 2019 21:37:29 +0100 Subject: [PATCH] libbpf: Propagate EPERM to caller on program load MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When loading an eBPF program, libbpf overrides the return code for EPERM errors instead of returning it to the caller. This makes it hard to figure out what went wrong on load. In particular, EPERM is returned when the system rlimit is too low to lock the memory required for the BPF program. Previously, this was somewhat obscured because the rlimit error would be hit on map creation (which does return it correctly). However, since maps can now be reused, object load can proceed all the way to loading programs without hitting the error; propagating it even in this case makes it possible for the caller to react appropriately (and, e.g., attempt to raise the rlimit before retrying). Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Acked-by: David S. Miller Acked-by: Song Liu Link: https://lore.kernel.org/bpf/157333184946.88376.11768171652794234561.stgit@toke.dk --- tools/lib/bpf/libbpf.c | 27 +++++++++++---------------- 1 file changed, 11 insertions(+), 16 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index d8ead85903d12..847b62895f9b5 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -3721,7 +3721,7 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, free(log_buf); goto retry_load; } - ret = -LIBBPF_ERRNO__LOAD; + ret = -errno; cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg)); pr_warn("load bpf program failed: %s\n", cp); @@ -3734,23 +3734,18 @@ load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt, pr_warn("Program too large (%zu insns), at most %d insns\n", load_attr.insns_cnt, BPF_MAXINSNS); ret = -LIBBPF_ERRNO__PROG2BIG; - } else { + } else if (load_attr.prog_type != BPF_PROG_TYPE_KPROBE) { /* Wrong program type? */ - if (load_attr.prog_type != BPF_PROG_TYPE_KPROBE) { - int fd; - - load_attr.prog_type = BPF_PROG_TYPE_KPROBE; - load_attr.expected_attach_type = 0; - fd = bpf_load_program_xattr(&load_attr, NULL, 0); - if (fd >= 0) { - close(fd); - ret = -LIBBPF_ERRNO__PROGTYPE; - goto out; - } - } + int fd; - if (log_buf) - ret = -LIBBPF_ERRNO__KVER; + load_attr.prog_type = BPF_PROG_TYPE_KPROBE; + load_attr.expected_attach_type = 0; + fd = bpf_load_program_xattr(&load_attr, NULL, 0); + if (fd >= 0) { + close(fd); + ret = -LIBBPF_ERRNO__PROGTYPE; + goto out; + } } out: