ipv4/raw: support binding to nonlocal addresses

Add support to inet v4 raw sockets for binding to nonlocal addresses
through the IP_FREEBIND and IP_TRANSPARENT socket options, as well as
the ipv4.ip_nonlocal_bind kernel parameter.

Add helper function to inet_sock.h to check for bind address validity on
the base of the address type and whether nonlocal address are enabled
for the socket via any of the sockopts/sysctl, deduplicating checks in
ipv4/ping.c, ipv4/af_inet.c, ipv6/af_inet6.c (for mapped v4->v6
addresses), and ipv4/raw.c.

Add test cases with IP[V6]_FREEBIND verifying that both v4 and v6 raw
sockets support binding to nonlocal addresses after the change. Add
necessary support for the test cases to nettest.

Signed-off-by: Riccardo Paolo Bestetti <pbl@bestov.io>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20211117090010.125393-1-pbl@bestov.io
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 32 insertions, 1 deletions

diff --git a/tools/testing/selftests/net/nettest.c b/tools/testing/selftests/net/nettest.c
index b599003eb5ba..d9a6fd2cd9d3 100644
--- a/tools/testing/selftests/net/nettest.c
+++ b/tools/testing/selftests/net/nettest.c
@@ -85,6 +85,7 @@ struct sock_args {
 	int version;   /* AF_INET/AF_INET6 */
 
 	int use_setsockopt;
+	int use_freebind;
 	int use_cmsg;
 	const char *dev;
 	const char *server_dev;
@@ -514,6 +515,29 @@ static int set_membership(int sd, uint32_t grp, uint32_t addr, int ifindex)
 	return 0;
 }
 
+static int set_freebind(int sd, int version)
+{
+	unsigned int one = 1;
+	int rc = 0;
+
+	switch (version) {
+	case AF_INET:
+		if (setsockopt(sd, SOL_IP, IP_FREEBIND, &one, sizeof(one))) {
+			log_err_errno("setsockopt(IP_FREEBIND)");
+			rc = -1;
+		}
+		break;
+	case AF_INET6:
+		if (setsockopt(sd, SOL_IPV6, IPV6_FREEBIND, &one, sizeof(one))) {
+			log_err_errno("setsockopt(IPV6_FREEBIND");
+			rc = -1;
+		}
+		break;
+	}
+
+	return rc;
+}
+
 static int set_broadcast(int sd)
 {
 	unsigned int one = 1;
@@ -1419,6 +1443,9 @@ static int lsock_init(struct sock_args *args)
 		 set_unicast_if(sd, args->ifindex, args->version))
 		goto err;
 
+	if (args->use_freebind && set_freebind(sd, args->version))
+		goto err;
+
 	if (bind_socket(sd, args))
 		goto err;
 
@@ -1827,7 +1854,7 @@ static int ipc_parent(int cpid, int fd, struct sock_args *args)
 	return client_status;
 }
 
-#define GETOPT_STR  "sr:l:c:p:t:g:P:DRn:M:X:m:d:I:BN:O:SCi6xL:0:1:2:3:Fbq"
+#define GETOPT_STR  "sr:l:c:p:t:g:P:DRn:M:X:m:d:I:BN:O:SCi6xL:0:1:2:3:Fbqf"
 #define OPT_FORCE_BIND_KEY_IFINDEX 1001
 #define OPT_NO_BIND_KEY_IFINDEX 1002
 
@@ -1864,6 +1891,7 @@ static void print_usage(char *prog)
 	"    -I dev        bind socket to given device name - server mode\n"
 	"    -S            use setsockopt (IP_UNICAST_IF or IP_MULTICAST_IF)\n"
 	"                  to set device binding\n"
+	"    -f            bind socket with the IP[V6]_FREEBIND option\n"
 	"    -C            use cmsg and IP_PKTINFO to specify device binding\n"
 	"\n"
 	"    -L len        send random message of given length\n"
@@ -1999,6 +2027,9 @@ int main(int argc, char *argv[])
 		case 'S':
 			args.use_setsockopt = 1;
 			break;
+		case 'f':
+			args.use_freebind = 1;
+			break;
 		case 'C':
 			args.use_cmsg = 1;
 			break;