Merge branch 'getpeername'

Daniel Borkmann says:

====================
Trivial patch to add get{peer,sock}name cgroup attach types to the BPF
sock_addr programs in order to enable rewriting sockaddr structs from
both calls along with libbpf and bpftool support as well as selftests.

Thanks!

v1 -> v2:
  - use __u16 for ports in start_server_with_port() signature and in
    expected_{local,peer} ports in the test case (Andrey)
  - Added both Andrii's and Andrey's ACKs
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

include/linux/bpf-cgroup.h

@@ -396,6 +396,7 @@ static inline int bpf_percpu_cgroup_storage_update(struct bpf_map *map,
 }
 
 #define cgroup_bpf_enabled (0)
+#define BPF_CGROUP_RUN_SA_PROG_LOCK(sk, uaddr, type, t_ctx) ({ 0; })
 #define BPF_CGROUP_PRE_CONNECT_ENABLED(sk) (0)
 #define BPF_CGROUP_RUN_PROG_INET_INGRESS(sk,skb) ({ 0; })
 #define BPF_CGROUP_RUN_PROG_INET_EGRESS(sk,skb) ({ 0; })

include/uapi/linux/bpf.h

@@ -220,6 +220,10 @@ enum bpf_attach_type {
 	BPF_MODIFY_RETURN,
 	BPF_LSM_MAC,
 	BPF_TRACE_ITER,
+	BPF_CGROUP_INET4_GETPEERNAME,
+	BPF_CGROUP_INET6_GETPEERNAME,
+	BPF_CGROUP_INET4_GETSOCKNAME,
+	BPF_CGROUP_INET6_GETSOCKNAME,
 	__MAX_BPF_ATTACH_TYPE
 };
 

kernel/bpf/syscall.c

@@ -1978,6 +1978,10 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type,
 		case BPF_CGROUP_INET6_BIND:
 		case BPF_CGROUP_INET4_CONNECT:
 		case BPF_CGROUP_INET6_CONNECT:
+		case BPF_CGROUP_INET4_GETPEERNAME:
+		case BPF_CGROUP_INET6_GETPEERNAME:
+		case BPF_CGROUP_INET4_GETSOCKNAME:
+		case BPF_CGROUP_INET6_GETSOCKNAME:
 		case BPF_CGROUP_UDP4_SENDMSG:
 		case BPF_CGROUP_UDP6_SENDMSG:
 		case BPF_CGROUP_UDP4_RECVMSG:
@@ -2767,6 +2771,10 @@ attach_type_to_prog_type(enum bpf_attach_type attach_type)
 	case BPF_CGROUP_INET6_BIND:
 	case BPF_CGROUP_INET4_CONNECT:
 	case BPF_CGROUP_INET6_CONNECT:
+	case BPF_CGROUP_INET4_GETPEERNAME:
+	case BPF_CGROUP_INET6_GETPEERNAME:
+	case BPF_CGROUP_INET4_GETSOCKNAME:
+	case BPF_CGROUP_INET6_GETSOCKNAME:
 	case BPF_CGROUP_UDP4_SENDMSG:
 	case BPF_CGROUP_UDP6_SENDMSG:
 	case BPF_CGROUP_UDP4_RECVMSG:
@@ -2912,6 +2920,10 @@ static int bpf_prog_query(const union bpf_attr *attr,
 	case BPF_CGROUP_INET6_POST_BIND:
 	case BPF_CGROUP_INET4_CONNECT:
 	case BPF_CGROUP_INET6_CONNECT:
+	case BPF_CGROUP_INET4_GETPEERNAME:
+	case BPF_CGROUP_INET6_GETPEERNAME:
+	case BPF_CGROUP_INET4_GETSOCKNAME:
+	case BPF_CGROUP_INET6_GETSOCKNAME:
 	case BPF_CGROUP_UDP4_SENDMSG:
 	case BPF_CGROUP_UDP6_SENDMSG:
 	case BPF_CGROUP_UDP4_RECVMSG:

kernel/bpf/verifier.c

@@ -7094,7 +7094,11 @@ static int check_return_code(struct bpf_verifier_env *env)
 	switch (env->prog->type) {
 	case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
 		if (env->prog->expected_attach_type == BPF_CGROUP_UDP4_RECVMSG ||
-		    env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG)
+		    env->prog->expected_attach_type == BPF_CGROUP_UDP6_RECVMSG ||
+		    env->prog->expected_attach_type == BPF_CGROUP_INET4_GETPEERNAME ||
+		    env->prog->expected_attach_type == BPF_CGROUP_INET6_GETPEERNAME ||
+		    env->prog->expected_attach_type == BPF_CGROUP_INET4_GETSOCKNAME ||
+		    env->prog->expected_attach_type == BPF_CGROUP_INET6_GETSOCKNAME)
 			range = tnum_range(1, 1);
 		break;
 	case BPF_PROG_TYPE_CGROUP_SKB:

net/core/filter.c

@@ -7049,6 +7049,8 @@ static bool sock_addr_is_valid_access(int off, int size,
 		switch (prog->expected_attach_type) {
 		case BPF_CGROUP_INET4_BIND:
 		case BPF_CGROUP_INET4_CONNECT:
+		case BPF_CGROUP_INET4_GETPEERNAME:
+		case BPF_CGROUP_INET4_GETSOCKNAME:
 		case BPF_CGROUP_UDP4_SENDMSG:
 		case BPF_CGROUP_UDP4_RECVMSG:
 			break;
@@ -7060,6 +7062,8 @@ static bool sock_addr_is_valid_access(int off, int size,
 		switch (prog->expected_attach_type) {
 		case BPF_CGROUP_INET6_BIND:
 		case BPF_CGROUP_INET6_CONNECT:
+		case BPF_CGROUP_INET6_GETPEERNAME:
+		case BPF_CGROUP_INET6_GETSOCKNAME:
 		case BPF_CGROUP_UDP6_SENDMSG:
 		case BPF_CGROUP_UDP6_RECVMSG:
 			break;

net/ipv4/af_inet.c

@@ -755,12 +755,11 @@ int inet_accept(struct socket *sock, struct socket *newsock, int flags,
 }
 EXPORT_SYMBOL(inet_accept);
 
-
 /*
  *	This does both peername and sockname.
  */
 int inet_getname(struct socket *sock, struct sockaddr *uaddr,
-			int peer)
+		 int peer)
 {
 	struct sock *sk		= sock->sk;
 	struct inet_sock *inet	= inet_sk(sk);
@@ -781,6 +780,11 @@ int inet_getname(struct socket *sock, struct sockaddr *uaddr,
 		sin->sin_port = inet->inet_sport;
 		sin->sin_addr.s_addr = addr;
 	}
+	if (cgroup_bpf_enabled)
+		BPF_CGROUP_RUN_SA_PROG_LOCK(sk, (struct sockaddr *)sin,
+					    peer ? BPF_CGROUP_INET4_GETPEERNAME :
+						   BPF_CGROUP_INET4_GETSOCKNAME,
+					    NULL);
 	memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
 	return sizeof(*sin);
 }

net/ipv6/af_inet6.c

@@ -504,9 +504,8 @@ EXPORT_SYMBOL_GPL(inet6_destroy_sock);
 /*
  *	This does both peername and sockname.
  */
-
 int inet6_getname(struct socket *sock, struct sockaddr *uaddr,
-		 int peer)
+		  int peer)
 {
 	struct sockaddr_in6 *sin = (struct sockaddr_in6 *)uaddr;
 	struct sock *sk = sock->sk;
@@ -531,9 +530,13 @@ int inet6_getname(struct socket *sock, struct sockaddr *uaddr,
 			sin->sin6_addr = np->saddr;
 		else
 			sin->sin6_addr = sk->sk_v6_rcv_saddr;
-
 		sin->sin6_port = inet->inet_sport;
 	}
+	if (cgroup_bpf_enabled)
+		BPF_CGROUP_RUN_SA_PROG_LOCK(sk, (struct sockaddr *)sin,
+					    peer ? BPF_CGROUP_INET6_GETPEERNAME :
+						   BPF_CGROUP_INET6_GETSOCKNAME,
+					    NULL);
 	sin->sin6_scope_id = ipv6_iface_scope_id(&sin->sin6_addr,
 						 sk->sk_bound_dev_if);
 	return sizeof(*sin);

tools/bpf/bpftool/Documentation/bpftool-cgroup.rst

@@ -29,8 +29,8 @@ CGROUP COMMANDS
 |	*PROG* := { **id** *PROG_ID* | **pinned** *FILE* | **tag** *PROG_TAG* }
 |	*ATTACH_TYPE* := { **ingress** | **egress** | **sock_create** | **sock_ops** | **device** |
 |		**bind4** | **bind6** | **post_bind4** | **post_bind6** | **connect4** | **connect6** |
-|		**sendmsg4** | **sendmsg6** | **recvmsg4** | **recvmsg6** | **sysctl** |
-|		**getsockopt** | **setsockopt** }
+|               **getpeername4** | **getpeername6** | **getsockname4** | **getsockname6** | **sendmsg4** |
+|               **sendmsg6** | **recvmsg4** | **recvmsg6** | **sysctl** | **getsockopt** | **setsockopt** }
 |	*ATTACH_FLAGS* := { **multi** | **override** }
 
 DESCRIPTION
@@ -101,7 +101,11 @@ DESCRIPTION
                   an unconnected udp6 socket (since 5.2);
 		  **sysctl** sysctl access (since 5.2);
 		  **getsockopt** call to getsockopt (since 5.3);
-		  **setsockopt** call to setsockopt (since 5.3).
+		  **setsockopt** call to setsockopt (since 5.3);
+		  **getpeername4** call to getpeername(2) for an inet4 socket (since 5.8);
+		  **getpeername6** call to getpeername(2) for an inet6 socket (since 5.8);
+		  **getsockname4** call to getsockname(2) for an inet4 socket (since 5.8);
+		  **getsockname6** call to getsockname(2) for an inet6 socket (since 5.8).
 
 	**bpftool cgroup detach** *CGROUP* *ATTACH_TYPE* *PROG*
 		  Detach *PROG* from the cgroup *CGROUP* and attach type

tools/bpf/bpftool/Documentation/bpftool-prog.rst

@@ -41,7 +41,8 @@ PROG COMMANDS
 |		**cgroup/sock** | **cgroup/dev** | **lwt_in** | **lwt_out** | **lwt_xmit** |
 |		**lwt_seg6local** | **sockops** | **sk_skb** | **sk_msg** | **lirc_mode2** |
 |		**cgroup/bind4** | **cgroup/bind6** | **cgroup/post_bind4** | **cgroup/post_bind6** |
-|		**cgroup/connect4** | **cgroup/connect6** | **cgroup/sendmsg4** | **cgroup/sendmsg6** |
+|		**cgroup/connect4** | **cgroup/connect6** | **cgroup/getpeername4** | **cgroup/getpeername6** |
+|               **cgroup/getsockname4** | **cgroup/getsockname6** | **cgroup/sendmsg4** | **cgroup/sendmsg6** |
 |		**cgroup/recvmsg4** | **cgroup/recvmsg6** | **cgroup/sysctl** |
 |		**cgroup/getsockopt** | **cgroup/setsockopt** |
 |		**struct_ops** | **fentry** | **fexit** | **freplace**

tools/bpf/bpftool/bash-completion/bpftool

@@ -472,6 +472,8 @@ _bpftool()
                                 lwt_seg6local sockops sk_skb sk_msg \
                                 lirc_mode2 cgroup/bind4 cgroup/bind6 \
                                 cgroup/connect4 cgroup/connect6 \
+                                cgroup/getpeername4 cgroup/getpeername6 \
+                                cgroup/getsockname4 cgroup/getsockname6 \
                                 cgroup/sendmsg4 cgroup/sendmsg6 \
                                 cgroup/recvmsg4 cgroup/recvmsg6 \
                                 cgroup/post_bind4 cgroup/post_bind6 \
@@ -966,9 +968,10 @@ _bpftool()
                     ;;
                 attach|detach)
                     local ATTACH_TYPES='ingress egress sock_create sock_ops \
-                        device bind4 bind6 post_bind4 post_bind6 connect4 \
-                        connect6 sendmsg4 sendmsg6 recvmsg4 recvmsg6 sysctl \
-                        getsockopt setsockopt'
+                        device bind4 bind6 post_bind4 post_bind6 connect4 connect6 \
+                        getpeername4 getpeername6 getsockname4 getsockname6 \
+                        sendmsg4 sendmsg6 recvmsg4 recvmsg6 sysctl getsockopt \
+                        setsockopt'
                     local ATTACH_FLAGS='multi override'
                     local PROG_TYPE='id pinned tag name'
                     case $prev in
@@ -977,9 +980,9 @@ _bpftool()
                             return 0
                             ;;
                         ingress|egress|sock_create|sock_ops|device|bind4|bind6|\
-                        post_bind4|post_bind6|connect4|connect6|sendmsg4|\
-                        sendmsg6|recvmsg4|recvmsg6|sysctl|getsockopt|\
-                        setsockopt)
+                        post_bind4|post_bind6|connect4|connect6|getpeername4|\
+                        getpeername6|getsockname4|getsockname6|sendmsg4|sendmsg6|\
+                        recvmsg4|recvmsg6|sysctl|getsockopt|setsockopt)
                             COMPREPLY=( $( compgen -W "$PROG_TYPE" -- \
                                 "$cur" ) )
                             return 0

tools/bpf/bpftool/cgroup.c

@@ -25,9 +25,10 @@
 	"       ATTACH_TYPE := { ingress | egress | sock_create |\n"	       \
 	"                        sock_ops | device | bind4 | bind6 |\n"	       \
 	"                        post_bind4 | post_bind6 | connect4 |\n"       \
-	"                        connect6 | sendmsg4 | sendmsg6 |\n"           \
-	"                        recvmsg4 | recvmsg6 | sysctl |\n"	       \
-	"                        getsockopt | setsockopt }"
+	"                        connect6 | getpeername4 | getpeername6 |\n"   \
+	"                        getsockname4 | getsockname6 | sendmsg4 |\n"   \
+	"                        sendmsg6 | recvmsg4 | recvmsg6 |\n"           \
+	"                        sysctl | getsockopt | setsockopt }"
 
 static unsigned int query_flags;
 

tools/bpf/bpftool/main.h

@@ -100,6 +100,10 @@ static const char * const attach_type_name[__MAX_BPF_ATTACH_TYPE] = {
 	[BPF_CGROUP_INET6_CONNECT] = "connect6",
 	[BPF_CGROUP_INET4_POST_BIND] = "post_bind4",
 	[BPF_CGROUP_INET6_POST_BIND] = "post_bind6",
+	[BPF_CGROUP_INET4_GETPEERNAME] = "getpeername4",
+	[BPF_CGROUP_INET6_GETPEERNAME] = "getpeername6",
+	[BPF_CGROUP_INET4_GETSOCKNAME] = "getsockname4",
+	[BPF_CGROUP_INET6_GETSOCKNAME] = "getsockname6",
 	[BPF_CGROUP_UDP4_SENDMSG] = "sendmsg4",
 	[BPF_CGROUP_UDP6_SENDMSG] = "sendmsg6",
 	[BPF_CGROUP_SYSCTL] = "sysctl",

tools/bpf/bpftool/prog.c

@@ -2012,8 +2012,10 @@ static int do_help(int argc, char **argv)
 		"                 sk_reuseport | flow_dissector | cgroup/sysctl |\n"
 		"                 cgroup/bind4 | cgroup/bind6 | cgroup/post_bind4 |\n"
 		"                 cgroup/post_bind6 | cgroup/connect4 | cgroup/connect6 |\n"
-		"                 cgroup/sendmsg4 | cgroup/sendmsg6 | cgroup/recvmsg4 |\n"
-		"                 cgroup/recvmsg6 | cgroup/getsockopt | cgroup/setsockopt |\n"
+		"                 cgroup/getpeername4 | cgroup/getpeername6 |\n"
+		"                 cgroup/getsockname4 | cgroup/getsockname6 | cgroup/sendmsg4 |\n"
+		"                 cgroup/sendmsg6 | cgroup/recvmsg4 | cgroup/recvmsg6 |\n"
+		"                 cgroup/getsockopt | cgroup/setsockopt |\n"
 		"                 struct_ops | fentry | fexit | freplace }\n"
 		"       ATTACH_TYPE := { msg_verdict | stream_verdict | stream_parser |\n"
 		"                        flow_dissector }\n"

tools/include/uapi/linux/bpf.h

@@ -220,6 +220,10 @@ enum bpf_attach_type {
 	BPF_MODIFY_RETURN,
 	BPF_LSM_MAC,
 	BPF_TRACE_ITER,
+	BPF_CGROUP_INET4_GETPEERNAME,
+	BPF_CGROUP_INET6_GETPEERNAME,
+	BPF_CGROUP_INET4_GETSOCKNAME,
+	BPF_CGROUP_INET6_GETSOCKNAME,
 	__MAX_BPF_ATTACH_TYPE
 };
 

tools/lib/bpf/libbpf.c

@@ -6705,6 +6705,14 @@ static const struct bpf_sec_def section_defs[] = {
 						BPF_CGROUP_UDP4_RECVMSG),
 	BPF_EAPROG_SEC("cgroup/recvmsg6",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
 						BPF_CGROUP_UDP6_RECVMSG),
+	BPF_EAPROG_SEC("cgroup/getpeername4",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_INET4_GETPEERNAME),
+	BPF_EAPROG_SEC("cgroup/getpeername6",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_INET6_GETPEERNAME),
+	BPF_EAPROG_SEC("cgroup/getsockname4",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_INET4_GETSOCKNAME),
+	BPF_EAPROG_SEC("cgroup/getsockname6",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_INET6_GETSOCKNAME),
 	BPF_EAPROG_SEC("cgroup/sysctl",		BPF_PROG_TYPE_CGROUP_SYSCTL,
 						BPF_CGROUP_SYSCTL),
 	BPF_EAPROG_SEC("cgroup/getsockopt",	BPF_PROG_TYPE_CGROUP_SOCKOPT,

tools/testing/selftests/bpf/network_helpers.c

@@ -5,6 +5,8 @@
 #include <string.h>
 #include <unistd.h>
 
+#include <arpa/inet.h>
+
 #include <sys/epoll.h>
 
 #include <linux/err.h>
@@ -35,7 +37,7 @@ struct ipv6_packet pkt_v6 = {
 	.tcp.doff = 5,
 };
 
-int start_server(int family, int type)
+int start_server_with_port(int family, int type, __u16 port)
 {
 	struct sockaddr_storage addr = {};
 	socklen_t len;
@@ -45,11 +47,13 @@ int start_server(int family, int type)
 		struct sockaddr_in *sin = (void *)&addr;
 
 		sin->sin_family = AF_INET;
+		sin->sin_port = htons(port);
 		len = sizeof(*sin);
 	} else {
 		struct sockaddr_in6 *sin6 = (void *)&addr;
 
 		sin6->sin6_family = AF_INET6;
+		sin6->sin6_port = htons(port);
 		len = sizeof(*sin6);
 	}
 
@@ -76,6 +80,11 @@ int start_server(int family, int type)
 	return fd;
 }
 
+int start_server(int family, int type)
+{
+	return start_server_with_port(family, type, 0);
+}
+
 static const struct timeval timeo_sec = { .tv_sec = 3 };
 static const size_t timeo_optlen = sizeof(timeo_sec);
 

tools/testing/selftests/bpf/network_helpers.h

@@ -34,6 +34,7 @@ struct ipv6_packet {
 extern struct ipv6_packet pkt_v6;
 
 int start_server(int family, int type);
+int start_server_with_port(int family, int type, __u16 port);
 int connect_to_fd(int family, int type, int server_fd);
 int connect_fd_to_fd(int client_fd, int server_fd);
 int connect_wait(int client_fd);

tools/testing/selftests/bpf/prog_tests/connect_force_port.c

@@ -4,7 +4,8 @@
 #include "cgroup_helpers.h"
 #include "network_helpers.h"
 
-static int verify_port(int family, int fd, int expected)
+static int verify_ports(int family, int fd,
+			__u16 expected_local, __u16 expected_peer)
 {
 	struct sockaddr_storage addr;
 	socklen_t len = sizeof(addr);
@@ -20,9 +21,25 @@ static int verify_port(int family, int fd, int expected)
 	else
 		port = ((struct sockaddr_in6 *)&addr)->sin6_port;
 
-	if (ntohs(port) != expected) {
-		log_err("Unexpected port %d, expected %d", ntohs(port),
-			expected);
+	if (ntohs(port) != expected_local) {
+		log_err("Unexpected local port %d, expected %d", ntohs(port),
+			expected_local);
+		return -1;
+	}
+
+	if (getpeername(fd, (struct sockaddr *)&addr, &len)) {
+		log_err("Failed to get peer addr");
+		return -1;
+	}
+
+	if (family == AF_INET)
+		port = ((struct sockaddr_in *)&addr)->sin_port;
+	else
+		port = ((struct sockaddr_in6 *)&addr)->sin6_port;
+
+	if (ntohs(port) != expected_peer) {
+		log_err("Unexpected peer port %d, expected %d", ntohs(port),
+			expected_peer);
 		return -1;
 	}
 
@@ -31,33 +48,67 @@ static int verify_port(int family, int fd, int expected)
 
 static int run_test(int cgroup_fd, int server_fd, int family, int type)
 {
+	bool v4 = family == AF_INET;
+	__u16 expected_local_port = v4 ? 22222 : 22223;
+	__u16 expected_peer_port = 60000;
 	struct bpf_prog_load_attr attr = {
-		.prog_type = BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+		.file = v4 ? "./connect_force_port4.o" :
+			     "./connect_force_port6.o",
 	};
+	struct bpf_program *prog;
 	struct bpf_object *obj;
-	int expected_port;
-	int prog_fd;
-	int err;
-	int fd;
-
-	if (family == AF_INET) {
-		attr.file = "./connect_force_port4.o";
-		attr.expected_attach_type = BPF_CGROUP_INET4_CONNECT;
-		expected_port = 22222;
-	} else {
-		attr.file = "./connect_force_port6.o";
-		attr.expected_attach_type = BPF_CGROUP_INET6_CONNECT;
-		expected_port = 22223;
-	}
+	int xlate_fd, fd, err;
+	__u32 duration = 0;
 
-	err = bpf_prog_load_xattr(&attr, &obj, &prog_fd);
+	err = bpf_prog_load_xattr(&attr, &obj, &xlate_fd);
 	if (err) {
 		log_err("Failed to load BPF object");
 		return -1;
 	}
 
-	err = bpf_prog_attach(prog_fd, cgroup_fd, attr.expected_attach_type,
-			      0);
+	prog = bpf_object__find_program_by_title(obj, v4 ?
+						 "cgroup/connect4" :
+						 "cgroup/connect6");
+	if (CHECK(!prog, "find_prog", "connect prog not found\n")) {
+		err = -EIO;
+		goto close_bpf_object;
+	}
+
+	err = bpf_prog_attach(bpf_program__fd(prog), cgroup_fd, v4 ?
+			      BPF_CGROUP_INET4_CONNECT :
+			      BPF_CGROUP_INET6_CONNECT, 0);
+	if (err) {
+		log_err("Failed to attach BPF program");
+		goto close_bpf_object;
+	}
+
+	prog = bpf_object__find_program_by_title(obj, v4 ?
+						 "cgroup/getpeername4" :
+						 "cgroup/getpeername6");
+	if (CHECK(!prog, "find_prog", "getpeername prog not found\n")) {
+		err = -EIO;
+		goto close_bpf_object;
+	}
+
+	err = bpf_prog_attach(bpf_program__fd(prog), cgroup_fd, v4 ?
+			      BPF_CGROUP_INET4_GETPEERNAME :
+			      BPF_CGROUP_INET6_GETPEERNAME, 0);
+	if (err) {
+		log_err("Failed to attach BPF program");
+		goto close_bpf_object;
+	}
+
+	prog = bpf_object__find_program_by_title(obj, v4 ?
+						 "cgroup/getsockname4" :
+						 "cgroup/getsockname6");
+	if (CHECK(!prog, "find_prog", "getsockname prog not found\n")) {
+		err = -EIO;
+		goto close_bpf_object;
+	}
+
+	err = bpf_prog_attach(bpf_program__fd(prog), cgroup_fd, v4 ?
+			      BPF_CGROUP_INET4_GETSOCKNAME :
+			      BPF_CGROUP_INET6_GETSOCKNAME, 0);
 	if (err) {
 		log_err("Failed to attach BPF program");
 		goto close_bpf_object;
@@ -69,8 +120,8 @@ static int run_test(int cgroup_fd, int server_fd, int family, int type)
 		goto close_bpf_object;
 	}
 
-	err = verify_port(family, fd, expected_port);
-
+	err = verify_ports(family, fd, expected_local_port,
+			   expected_peer_port);
 	close(fd);
 
 close_bpf_object:
@@ -86,25 +137,25 @@ void test_connect_force_port(void)
 	if (CHECK_FAIL(cgroup_fd < 0))
 		return;
 
-	server_fd = start_server(AF_INET, SOCK_STREAM);
+	server_fd = start_server_with_port(AF_INET, SOCK_STREAM, 60123);
 	if (CHECK_FAIL(server_fd < 0))
 		goto close_cgroup_fd;
 	CHECK_FAIL(run_test(cgroup_fd, server_fd, AF_INET, SOCK_STREAM));
 	close(server_fd);
 
-	server_fd = start_server(AF_INET6, SOCK_STREAM);
+	server_fd = start_server_with_port(AF_INET6, SOCK_STREAM, 60124);
 	if (CHECK_FAIL(server_fd < 0))
 		goto close_cgroup_fd;
 	CHECK_FAIL(run_test(cgroup_fd, server_fd, AF_INET6, SOCK_STREAM));
 	close(server_fd);
 
-	server_fd = start_server(AF_INET, SOCK_DGRAM);
+	server_fd = start_server_with_port(AF_INET, SOCK_DGRAM, 60123);
 	if (CHECK_FAIL(server_fd < 0))
 		goto close_cgroup_fd;
 	CHECK_FAIL(run_test(cgroup_fd, server_fd, AF_INET, SOCK_DGRAM));
 	close(server_fd);
 
-	server_fd = start_server(AF_INET6, SOCK_DGRAM);
+	server_fd = start_server_with_port(AF_INET6, SOCK_DGRAM, 60124);
 	if (CHECK_FAIL(server_fd < 0))
 		goto close_cgroup_fd;
 	CHECK_FAIL(run_test(cgroup_fd, server_fd, AF_INET6, SOCK_DGRAM));

tools/testing/selftests/bpf/progs/connect_force_port4.c

 // SPDX-License-Identifier: GPL-2.0
 #include <string.h>
+#include <stdbool.h>
 
 #include <linux/bpf.h>
 #include <linux/in.h>
@@ -12,17 +13,71 @@
 char _license[] SEC("license") = "GPL";
 int _version SEC("version") = 1;
 
+struct svc_addr {
+	__be32 addr;
+	__be16 port;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_SK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+	__type(key, int);
+	__type(value, struct svc_addr);
+} service_mapping SEC(".maps");
+
 SEC("cgroup/connect4")
-int _connect4(struct bpf_sock_addr *ctx)
+int connect4(struct bpf_sock_addr *ctx)
 {
 	struct sockaddr_in sa = {};
+	struct svc_addr *orig;
 
+	/* Force local address to 127.0.0.1:22222. */
 	sa.sin_family = AF_INET;
 	sa.sin_port = bpf_htons(22222);
-	sa.sin_addr.s_addr = bpf_htonl(0x7f000001); /* 127.0.0.1 */
+	sa.sin_addr.s_addr = bpf_htonl(0x7f000001);
 
 	if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
 		return 0;
 
+	/* Rewire service 1.2.3.4:60000 to backend 127.0.0.1:60123. */
+	if (ctx->user_port == bpf_htons(60000)) {
+		orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0,
+					  BPF_SK_STORAGE_GET_F_CREATE);
+		if (!orig)
+			return 0;
+
+		orig->addr = ctx->user_ip4;
+		orig->port = ctx->user_port;
+
+		ctx->user_ip4 = bpf_htonl(0x7f000001);
+		ctx->user_port = bpf_htons(60123);
+	}
+	return 1;
+}
+
+SEC("cgroup/getsockname4")
+int getsockname4(struct bpf_sock_addr *ctx)
+{
+	/* Expose local server as 1.2.3.4:60000 to client. */
+	if (ctx->user_port == bpf_htons(60123)) {
+		ctx->user_ip4 = bpf_htonl(0x01020304);
+		ctx->user_port = bpf_htons(60000);
+	}
+	return 1;
+}
+
+SEC("cgroup/getpeername4")
+int getpeername4(struct bpf_sock_addr *ctx)
+{
+	struct svc_addr *orig;
+
+	/* Expose service 1.2.3.4:60000 as peer instead of backend. */
+	if (ctx->user_port == bpf_htons(60123)) {
+		orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 0);
+		if (orig) {
+			ctx->user_ip4 = orig->addr;
+			ctx->user_port = orig->port;
+		}
+	}
 	return 1;
 }

tools/testing/selftests/bpf/progs/connect_force_port6.c

@@ -12,17 +12,83 @@
 char _license[] SEC("license") = "GPL";
 int _version SEC("version") = 1;
 
+struct svc_addr {
+	__be32 addr[4];
+	__be16 port;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_SK_STORAGE);
+	__uint(map_flags, BPF_F_NO_PREALLOC);
+	__type(key, int);
+	__type(value, struct svc_addr);
+} service_mapping SEC(".maps");
+
 SEC("cgroup/connect6")
-int _connect6(struct bpf_sock_addr *ctx)
+int connect6(struct bpf_sock_addr *ctx)
 {
 	struct sockaddr_in6 sa = {};
+	struct svc_addr *orig;
 
+	/* Force local address to [::1]:22223. */
 	sa.sin6_family = AF_INET6;
 	sa.sin6_port = bpf_htons(22223);
-	sa.sin6_addr.s6_addr32[3] = bpf_htonl(1); /* ::1 */
+	sa.sin6_addr.s6_addr32[3] = bpf_htonl(1);
 
 	if (bpf_bind(ctx, (struct sockaddr *)&sa, sizeof(sa)) != 0)
 		return 0;
 
+	/* Rewire service [fc00::1]:60000 to backend [::1]:60124. */
+	if (ctx->user_port == bpf_htons(60000)) {
+		orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0,
+					  BPF_SK_STORAGE_GET_F_CREATE);
+		if (!orig)
+			return 0;
+
+		orig->addr[0] = ctx->user_ip6[0];
+		orig->addr[1] = ctx->user_ip6[1];
+		orig->addr[2] = ctx->user_ip6[2];
+		orig->addr[3] = ctx->user_ip6[3];
+		orig->port = ctx->user_port;
+
+		ctx->user_ip6[0] = 0;
+		ctx->user_ip6[1] = 0;
+		ctx->user_ip6[2] = 0;
+		ctx->user_ip6[3] = bpf_htonl(1);
+		ctx->user_port = bpf_htons(60124);
+	}
+	return 1;
+}
+
+SEC("cgroup/getsockname6")
+int getsockname6(struct bpf_sock_addr *ctx)
+{
+	/* Expose local server as [fc00::1]:60000 to client. */
+	if (ctx->user_port == bpf_htons(60124)) {
+		ctx->user_ip6[0] = bpf_htonl(0xfc000000);
+		ctx->user_ip6[1] = 0;
+		ctx->user_ip6[2] = 0;
+		ctx->user_ip6[3] = bpf_htonl(1);
+		ctx->user_port = bpf_htons(60000);
+	}
+	return 1;
+}
+
+SEC("cgroup/getpeername6")
+int getpeername6(struct bpf_sock_addr *ctx)
+{
+	struct svc_addr *orig;
+
+	/* Expose service [fc00::1]:60000 as peer instead of backend. */
+	if (ctx->user_port == bpf_htons(60124)) {
+		orig = bpf_sk_storage_get(&service_mapping, ctx->sk, 0, 0);
+		if (orig) {
+			ctx->user_ip6[0] = orig->addr[0];
+			ctx->user_ip6[1] = orig->addr[1];
+			ctx->user_ip6[2] = orig->addr[2];
+			ctx->user_ip6[3] = orig->addr[3];
+			ctx->user_port = orig->port;
+		}
+	}
 	return 1;
 }