On 9/18/18 1:20 PM, Willem de Bruijn wrote:
> From: Willem de Bruijn <will...@google.com>
>
> If boolean CONFIG_BPF_SYSCALL is enabled, kernel/bpf/syscall.c will
> call flow_dissector functions from net/core/flow_dissector.c.
>
> This causes this build failure if CONFIG_NET is disabled:
>
> kernel/bpf/syscall.o: In function `__x64_sys_bpf':
> syscall.c:(.text+0x3278): undefined reference to
> `skb_flow_dissector_bpf_prog_attach'
> syscall.c:(.text+0x3310): undefined reference to
> `skb_flow_dissector_bpf_prog_detach'
> kernel/bpf/syscall.o:(.rodata+0x3f0): undefined reference to
> `flow_dissector_prog_ops'
> kernel/bpf/verifier.o:(.rodata+0x250): undefined reference to
> `flow_dissector_verifier_ops'
>
> Analogous to other optional BPF program types in syscall.c, add stubs
> if the relevant functions are not compiled and move the BPF_PROG_TYPE
> definition in the #ifdef CONFIG_NET block.
>
> Fixes: d58e468b1112 ("flow_dissector: implements flow dissector BPF hook")
> Reported-by: Randy Dunlap <rdun...@infradead.org>
> Signed-off-by: Willem de Bruijn <will...@google.com>
Works for me. Thanks.
Acked-by: Randy Dunlap <rdun...@infradead.org> # build-tested
> ---
> include/linux/bpf_types.h | 2 +-
> include/linux/skbuff.h | 13 +++++++++++++
> 2 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
> index 22083712dd18..c9bd6fb765b0 100644
> --- a/include/linux/bpf_types.h
> +++ b/include/linux/bpf_types.h
> @@ -16,6 +16,7 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_LWT_SEG6LOCAL, lwt_seg6local)
> BPF_PROG_TYPE(BPF_PROG_TYPE_SOCK_OPS, sock_ops)
> BPF_PROG_TYPE(BPF_PROG_TYPE_SK_SKB, sk_skb)
> BPF_PROG_TYPE(BPF_PROG_TYPE_SK_MSG, sk_msg)
> +BPF_PROG_TYPE(BPF_PROG_TYPE_FLOW_DISSECTOR, flow_dissector)
> #endif
> #ifdef CONFIG_BPF_EVENTS
> BPF_PROG_TYPE(BPF_PROG_TYPE_KPROBE, kprobe)
> @@ -32,7 +33,6 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_LIRC_MODE2, lirc_mode2)
> #ifdef CONFIG_INET
> BPF_PROG_TYPE(BPF_PROG_TYPE_SK_REUSEPORT, sk_reuseport)
> #endif
> -BPF_PROG_TYPE(BPF_PROG_TYPE_FLOW_DISSECTOR, flow_dissector)
>
> BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
> BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index ce0e863f02a2..76be85ea392a 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -1194,10 +1194,23 @@ void skb_flow_dissector_init(struct flow_dissector
> *flow_dissector,
> const struct flow_dissector_key *key,
> unsigned int key_count);
>
> +#ifdef CONFIG_NET
> int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
> struct bpf_prog *prog);
>
> int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr);
> +#else
> +static inline int skb_flow_dissector_bpf_prog_attach(const union bpf_attr
> *attr,
> + struct bpf_prog *prog)
> +{
> + return -EOPNOTSUPP;
> +}
> +
> +static inline int skb_flow_dissector_bpf_prog_detach(const union bpf_attr
> *attr)
> +{
> + return -EOPNOTSUPP;
> +}
> +#endif
>
> bool __skb_flow_dissect(const struct sk_buff *skb,
> struct flow_dissector *flow_dissector,
>
--
~Randy
