bpf: Relax tuple len requirement for sk helpers.

__bpf_skc_lookup() safely handles incorrect values of tuple len,
hence we can allow zero to be passed as tuple len.
This patch alone doesn't make an observable verifier difference.
It's a trivial improvement that might simplify bpf programs.

Signed-off-by: Alexei Starovoitov <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Acked-by: Eduard Zingerman <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

Author: Alexei Starovoitov

net/core/filter.c

@@ -6815,7 +6815,7 @@ static const struct bpf_func_proto bpf_skc_lookup_tcp_proto = {
 	.ret_type	= RET_PTR_TO_SOCK_COMMON_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
-	.arg3_type	= ARG_CONST_SIZE,
+	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
 };
@@ -6834,7 +6834,7 @@ static const struct bpf_func_proto bpf_sk_lookup_tcp_proto = {
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
-	.arg3_type	= ARG_CONST_SIZE,
+	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
 };
@@ -6853,7 +6853,7 @@ static const struct bpf_func_proto bpf_sk_lookup_udp_proto = {
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
-	.arg3_type	= ARG_CONST_SIZE,
+	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
 };
@@ -6877,7 +6877,7 @@ static const struct bpf_func_proto bpf_tc_skc_lookup_tcp_proto = {
 	.ret_type	= RET_PTR_TO_SOCK_COMMON_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
-	.arg3_type	= ARG_CONST_SIZE,
+	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
 };
@@ -6901,7 +6901,7 @@ static const struct bpf_func_proto bpf_tc_sk_lookup_tcp_proto = {
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
-	.arg3_type	= ARG_CONST_SIZE,
+	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
 };
@@ -6925,7 +6925,7 @@ static const struct bpf_func_proto bpf_tc_sk_lookup_udp_proto = {
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
-	.arg3_type	= ARG_CONST_SIZE,
+	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
 };
@@ -6963,7 +6963,7 @@ static const struct bpf_func_proto bpf_xdp_sk_lookup_udp_proto = {
 	.ret_type       = RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type      = ARG_PTR_TO_CTX,
 	.arg2_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
-	.arg3_type      = ARG_CONST_SIZE,
+	.arg3_type      = ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type      = ARG_ANYTHING,
 	.arg5_type      = ARG_ANYTHING,
 };
@@ -6987,7 +6987,7 @@ static const struct bpf_func_proto bpf_xdp_skc_lookup_tcp_proto = {
 	.ret_type       = RET_PTR_TO_SOCK_COMMON_OR_NULL,
 	.arg1_type      = ARG_PTR_TO_CTX,
 	.arg2_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
-	.arg3_type      = ARG_CONST_SIZE,
+	.arg3_type      = ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type      = ARG_ANYTHING,
 	.arg5_type      = ARG_ANYTHING,
 };
@@ -7011,7 +7011,7 @@ static const struct bpf_func_proto bpf_xdp_sk_lookup_tcp_proto = {
 	.ret_type       = RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type      = ARG_PTR_TO_CTX,
 	.arg2_type      = ARG_PTR_TO_MEM | MEM_RDONLY,
-	.arg3_type      = ARG_CONST_SIZE,
+	.arg3_type      = ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type      = ARG_ANYTHING,
 	.arg5_type      = ARG_ANYTHING,
 };
@@ -7031,7 +7031,7 @@ static const struct bpf_func_proto bpf_sock_addr_skc_lookup_tcp_proto = {
 	.ret_type	= RET_PTR_TO_SOCK_COMMON_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
-	.arg3_type	= ARG_CONST_SIZE,
+	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
 };
@@ -7050,7 +7050,7 @@ static const struct bpf_func_proto bpf_sock_addr_sk_lookup_tcp_proto = {
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
-	.arg3_type	= ARG_CONST_SIZE,
+	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
 };
@@ -7069,7 +7069,7 @@ static const struct bpf_func_proto bpf_sock_addr_sk_lookup_udp_proto = {
 	.ret_type	= RET_PTR_TO_SOCKET_OR_NULL,
 	.arg1_type	= ARG_PTR_TO_CTX,
 	.arg2_type	= ARG_PTR_TO_MEM | MEM_RDONLY,
-	.arg3_type	= ARG_CONST_SIZE,
+	.arg3_type	= ARG_CONST_SIZE_OR_ZERO,
 	.arg4_type	= ARG_ANYTHING,
 	.arg5_type	= ARG_ANYTHING,
 };