bpf: sock_map fixes for !CONFIG_BPF_SYSCALL and !STREAM_PARSER

Resolve issues with !CONFIG_BPF_SYSCALL and !STREAM_PARSER

net/core/filter.c: In function ‘do_sk_redirect_map’:
net/core/filter.c:1881:3: error: implicit declaration of function ‘__sock_map_lookup_elem’ [-Werror=implicit-function-declaration]
   sk = __sock_map_lookup_elem(ri->map, ri->ifindex);
   ^
net/core/filter.c:1881:6: warning: assignment makes pointer from integer without a cast [enabled by default]
   sk = __sock_map_lookup_elem(ri->map, ri->ifindex);

Fixes: 174a79ff ("bpf: sockmap with sk redirect support")
Reported-by: NEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NJohn Fastabend <john.fastabend@gmail.com>
Acked-by: NDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/bpf.h

@@ -313,7 +313,6 @@ int bpf_check(struct bpf_prog **fp, union bpf_attr *attr);
 
 /* Map specifics */
 struct net_device  *__dev_map_lookup_elem(struct bpf_map *map, u32 key);
-struct sock  *__sock_map_lookup_elem(struct bpf_map *map, u32 key);
 void __dev_map_insert_ctx(struct bpf_map *map, u32 index);
 void __dev_map_flush(struct bpf_map *map);
 
@@ -377,6 +376,15 @@ static inline void __dev_map_flush(struct bpf_map *map)
 }
 #endif /* CONFIG_BPF_SYSCALL */
 
+#if defined(CONFIG_STREAM_PARSER) && defined(CONFIG_BPF_SYSCALL)
+struct sock  *__sock_map_lookup_elem(struct bpf_map *map, u32 key);
+#else
+static inline struct sock  *__sock_map_lookup_elem(struct bpf_map *map, u32 key)
+{
+	return NULL;
+}
+#endif
+
 /* verifier prototypes for helper functions called from eBPF programs */
 extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
 extern const struct bpf_func_proto bpf_map_update_elem_proto;

include/linux/bpf_types.h

@@ -38,5 +38,7 @@ BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY_OF_MAPS, array_of_maps_map_ops)
 BPF_MAP_TYPE(BPF_MAP_TYPE_HASH_OF_MAPS, htab_of_maps_map_ops)
 #ifdef CONFIG_NET
 BPF_MAP_TYPE(BPF_MAP_TYPE_DEVMAP, dev_map_ops)
+#ifdef CONFIG_STREAM_PARSER
 BPF_MAP_TYPE(BPF_MAP_TYPE_SOCKMAP, sock_map_ops)
 #endif
+#endif

kernel/bpf/Makefile

@@ -3,7 +3,10 @@ obj-y := core.o
 obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o
 obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o
 ifeq ($(CONFIG_NET),y)
-obj-$(CONFIG_BPF_SYSCALL) += devmap.o sockmap.o
+obj-$(CONFIG_BPF_SYSCALL) += devmap.o
+ifeq ($(CONFIG_STREAM_PARSER),y)
+obj-$(CONFIG_BPF_SYSCALL) += sockmap.o
+endif
 endif
 ifeq ($(CONFIG_PERF_EVENTS),y)
 obj-$(CONFIG_BPF_SYSCALL) += stackmap.o

kernel/bpf/core.c

@@ -1438,6 +1438,7 @@ const struct bpf_func_proto bpf_ktime_get_ns_proto __weak;
 const struct bpf_func_proto bpf_get_current_pid_tgid_proto __weak;
 const struct bpf_func_proto bpf_get_current_uid_gid_proto __weak;
 const struct bpf_func_proto bpf_get_current_comm_proto __weak;
+const struct bpf_func_proto bpf_sock_map_update_proto __weak;
 
 const struct bpf_func_proto * __weak bpf_get_trace_printk_proto(void)
 {