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    Subject[PATCH] bpf: fix building without CONFIG_INET
    Date
    The newly added TCP and UDP handling fails to link when CONFIG_INET
    is disabled:

    net/core/filter.o: In function `sk_lookup':
    filter.c:(.text+0x7ff8): undefined reference to `tcp_hashinfo'
    filter.c:(.text+0x7ffc): undefined reference to `tcp_hashinfo'
    filter.c:(.text+0x8020): undefined reference to `__inet_lookup_established'
    filter.c:(.text+0x8058): undefined reference to `__inet_lookup_listener'
    filter.c:(.text+0x8068): undefined reference to `udp_table'
    filter.c:(.text+0x8070): undefined reference to `udp_table'
    filter.c:(.text+0x808c): undefined reference to `__udp4_lib_lookup'
    net/core/filter.o: In function `bpf_sk_release':
    filter.c:(.text+0x82e8): undefined reference to `sock_gen_put'

    The compiler can optimize it out and avoid those references for
    the most part, but we are missing a few steps here:

    - sk_lookup() should always have been marked 'static', this also
    avoids a warning about a missing prototype when building with
    'make W=1'.
    - The BPF_CALL_x() macro needs a little change to allow marking
    the unneeded BPF call as 'static' and having the compiler
    drop them.
    - The reference to the bpf_func_proto must be made conditional.

    Fixes: 6acc9b432e67 ("bpf: Add helper to retrieve socket in BPF")
    Signed-off-by: Arnd Bergmann <arnd@arndb.de>
    ---
    include/linux/filter.h | 2 +-
    net/core/filter.c | 18 +++++++++++-------
    2 files changed, 12 insertions(+), 8 deletions(-)

    diff --git a/include/linux/filter.h b/include/linux/filter.h
    index 6791a0ac0139..d9ec9d908bbe 100644
    --- a/include/linux/filter.h
    +++ b/include/linux/filter.h
    @@ -428,9 +428,9 @@ struct sock_reuseport;
    u64, __ur_3, u64, __ur_4, u64, __ur_5)

    #define BPF_CALL_x(x, name, ...) \
    + u64 name(__BPF_REG(x, __BPF_DECL_REGS, __BPF_N, __VA_ARGS__)); \
    static __always_inline \
    u64 ____##name(__BPF_MAP(x, __BPF_DECL_ARGS, __BPF_V, __VA_ARGS__)); \
    - u64 name(__BPF_REG(x, __BPF_DECL_REGS, __BPF_N, __VA_ARGS__)); \
    u64 name(__BPF_REG(x, __BPF_DECL_REGS, __BPF_N, __VA_ARGS__)) \
    { \
    return ____##name(__BPF_MAP(x,__BPF_CAST,__BPF_N,__VA_ARGS__));\
    diff --git a/net/core/filter.c b/net/core/filter.c
    index 30c6b2d3ef16..dd5fe021f44c 100644
    --- a/net/core/filter.c
    +++ b/net/core/filter.c
    @@ -4817,7 +4817,7 @@ static const struct bpf_func_proto bpf_lwt_seg6_adjust_srh_proto = {
    };
    #endif /* CONFIG_IPV6_SEG6_BPF */

    -struct sock *sk_lookup(struct net *net, struct bpf_sock_tuple *tuple,
    +static struct sock *sk_lookup(struct net *net, struct bpf_sock_tuple *tuple,
    struct sk_buff *skb, u8 family, u8 proto)
    {
    int dif = skb->dev->ifindex;
    @@ -4902,13 +4902,13 @@ bpf_sk_lookup(struct sk_buff *skb, struct bpf_sock_tuple *tuple, u32 len,
    return (unsigned long) sk;
    }

    -BPF_CALL_5(bpf_sk_lookup_tcp, struct sk_buff *, skb,
    +static BPF_CALL_5(bpf_sk_lookup_tcp, struct sk_buff *, skb,
    struct bpf_sock_tuple *, tuple, u32, len, u64, netns_id, u64, flags)
    {
    return bpf_sk_lookup(skb, tuple, len, IPPROTO_TCP, netns_id, flags);
    }

    -static const struct bpf_func_proto bpf_sk_lookup_tcp_proto = {
    +static const __maybe_unused struct bpf_func_proto bpf_sk_lookup_tcp_proto = {
    .func = bpf_sk_lookup_tcp,
    .gpl_only = false,
    .pkt_access = true,
    @@ -4920,13 +4920,13 @@ static const struct bpf_func_proto bpf_sk_lookup_tcp_proto = {
    .arg5_type = ARG_ANYTHING,
    };

    -BPF_CALL_5(bpf_sk_lookup_udp, struct sk_buff *, skb,
    +static BPF_CALL_5(bpf_sk_lookup_udp, struct sk_buff *, skb,
    struct bpf_sock_tuple *, tuple, u32, len, u64, netns_id, u64, flags)
    {
    return bpf_sk_lookup(skb, tuple, len, IPPROTO_UDP, netns_id, flags);
    }

    -static const struct bpf_func_proto bpf_sk_lookup_udp_proto = {
    +static const __maybe_unused struct bpf_func_proto bpf_sk_lookup_udp_proto = {
    .func = bpf_sk_lookup_udp,
    .gpl_only = false,
    .pkt_access = true,
    @@ -4938,14 +4938,14 @@ static const struct bpf_func_proto bpf_sk_lookup_udp_proto = {
    .arg5_type = ARG_ANYTHING,
    };

    -BPF_CALL_1(bpf_sk_release, struct sock *, sk)
    +static BPF_CALL_1(bpf_sk_release, struct sock *, sk)
    {
    if (!sock_flag(sk, SOCK_RCU_FREE))
    sock_gen_put(sk);
    return 0;
    }

    -static const struct bpf_func_proto bpf_sk_release_proto = {
    +static const __maybe_unused struct bpf_func_proto bpf_sk_release_proto = {
    .func = bpf_sk_release,
    .gpl_only = false,
    .ret_type = RET_INTEGER,
    @@ -5158,12 +5158,14 @@ tc_cls_act_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
    case BPF_FUNC_skb_ancestor_cgroup_id:
    return &bpf_skb_ancestor_cgroup_id_proto;
    #endif
    +#ifdef CONFIG_INET
    case BPF_FUNC_sk_lookup_tcp:
    return &bpf_sk_lookup_tcp_proto;
    case BPF_FUNC_sk_lookup_udp:
    return &bpf_sk_lookup_udp_proto;
    case BPF_FUNC_sk_release:
    return &bpf_sk_release_proto;
    +#endif
    default:
    return bpf_base_func_proto(func_id);
    }
    @@ -5264,12 +5266,14 @@ sk_skb_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
    return &bpf_sk_redirect_hash_proto;
    case BPF_FUNC_get_local_storage:
    return &bpf_get_local_storage_proto;
    +#ifdef CONFIG_INET
    case BPF_FUNC_sk_lookup_tcp:
    return &bpf_sk_lookup_tcp_proto;
    case BPF_FUNC_sk_lookup_udp:
    return &bpf_sk_lookup_udp_proto;
    case BPF_FUNC_sk_release:
    return &bpf_sk_release_proto;
    +#endif
    default:
    return bpf_base_func_proto(func_id);
    }
    --
    2.18.0
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      Last update: 2018-10-05 18:17    [W:6.272 / U:0.008 seconds]
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