selftests/bpf: Selftest for sys_bind hooks

Add selftest to work with bpf_sock_addr context from
`BPF_PROG_TYPE_CGROUP_SOCK_ADDR` programs.

Try to bind(2) on IP:port and apply:
* loads to make sure context can be read correctly, including narrow
  loads (byte, half) for IP and full-size loads (word) for all fields;
* stores to those fields allowed by verifier.

All combination from IPv4/IPv6 and TCP/UDP are tested.

Both scenarios are tested:
* valid programs can be loaded and attached;
* invalid programs can be neither loaded nor attached.

Test passes when expected data can be read from context in the
BPF-program, and after the call to bind(2) socket is bound to IP:port
pair that was written by BPF-program to the context.

Example:
  # ./test_sock_addr
  Attached bind4 program.
  Test case #1 (IPv4/TCP):
          Requested: bind(192.168.1.254, 4040) ..
             Actual: bind(127.0.0.1, 4444)
  Test case #2 (IPv4/UDP):
          Requested: bind(192.168.1.254, 4040) ..
             Actual: bind(127.0.0.1, 4444)
  Attached bind6 program.
  Test case #3 (IPv6/TCP):
          Requested: bind(face:b00c:1234:5678::abcd, 6060) ..
             Actual: bind(::1, 6666)
  Test case #4 (IPv6/UDP):
          Requested: bind(face:b00c:1234:5678::abcd, 6060) ..
             Actual: bind(::1, 6666)
  ### SUCCESS

Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

4 files changed, 517 insertions, 1 deletions

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index e1c1fed63396..f2120c5c0578 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -136,6 +136,7 @@ enum bpf_prog_type {
         BPF_PROG_TYPE_CGROUP_DEVICE,
         BPF_PROG_TYPE_SK_MSG,
         BPF_PROG_TYPE_RAW_TRACEPOINT,
+        BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
 };
 
 enum bpf_attach_type {
@@ -147,6 +148,8 @@ enum bpf_attach_type {
         BPF_SK_SKB_STREAM_VERDICT,
         BPF_CGROUP_DEVICE,
         BPF_SK_MSG_VERDICT,
+        BPF_CGROUP_INET4_BIND,
+        BPF_CGROUP_INET6_BIND,
         __MAX_BPF_ATTACH_TYPE
 };
 
@@ -1009,6 +1012,26 @@ struct bpf_map_info {
         __u64 netns_ino;
 } __attribute__((aligned(8)));
 
+/* User bpf_sock_addr struct to access socket fields and sockaddr struct passed
+ * by user and intended to be used by socket (e.g. to bind to, depends on
+ * attach attach type).
+ */
+struct bpf_sock_addr {
+        __u32 user_family;      /* Allows 4-byte read, but no write. */
+        __u32 user_ip4;         /* Allows 1,2,4-byte read and 4-byte write.
+                                 * Stored in network byte order.
+                                 */
+        __u32 user_ip6[4];      /* Allows 1,2,4-byte read an 4-byte write.
+                                 * Stored in network byte order.
+                                 */
+        __u32 user_port;        /* Allows 4-byte read and write.
+                                 * Stored in network byte order
+                                 */
+        __u32 family;           /* Allows 4-byte read, but no write */
+        __u32 type;             /* Allows 4-byte read, but no write */
+        __u32 protocol;         /* Allows 4-byte read, but no write */
+};
+
 /* User bpf_sock_ops struct to access socket values and specify request ops
  * and their replies.
  * Some of this fields are in network (bigendian) byte order and may need
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 48e3e743ebf7..d7ce8818982c 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1859,6 +1859,9 @@ static void bpf_program__set_expected_attach_type(struct bpf_program *prog,
 
 #define BPF_PROG_SEC(string, ptype) BPF_PROG_SEC_FULL(string, ptype, 0)
 
+#define BPF_SA_PROG_SEC(string, ptype) \
+        BPF_PROG_SEC_FULL(string, BPF_PROG_TYPE_CGROUP_SOCK_ADDR, ptype)
+
 static const struct {
         const char *sec;
         size_t len;
@@ -1882,10 +1885,13 @@ static const struct {
         BPF_PROG_SEC("sockops",         BPF_PROG_TYPE_SOCK_OPS),
         BPF_PROG_SEC("sk_skb",          BPF_PROG_TYPE_SK_SKB),
         BPF_PROG_SEC("sk_msg",          BPF_PROG_TYPE_SK_MSG),
+        BPF_SA_PROG_SEC("cgroup/bind4", BPF_CGROUP_INET4_BIND),
+        BPF_SA_PROG_SEC("cgroup/bind6", BPF_CGROUP_INET6_BIND),
 };
 
 #undef BPF_PROG_SEC
 #undef BPF_PROG_SEC_FULL
+#undef BPF_SA_PROG_SEC
 
 static int bpf_program__identify_section(struct bpf_program *prog)
 {
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index f35fb02bdf56..f4717c910874 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -23,7 +23,7 @@ urandom_read: urandom_read.c
 
 # Order correspond to 'make run_tests' order
 TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \
-        test_align test_verifier_log test_dev_cgroup test_tcpbpf_user
+        test_align test_verifier_log test_dev_cgroup test_tcpbpf_user test_sock_addr
 
 TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test_obj_id.o \
         test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o     \
@@ -51,6 +51,7 @@ $(TEST_GEN_PROGS): $(BPFOBJ)
 $(TEST_GEN_PROGS_EXTENDED): $(OUTPUT)/libbpf.a
 
 $(OUTPUT)/test_dev_cgroup: cgroup_helpers.c
+$(OUTPUT)/test_sock_addr: cgroup_helpers.c
 
 .PHONY: force
 
diff --git a/tools/testing/selftests/bpf/test_sock_addr.c b/tools/testing/selftests/bpf/test_sock_addr.c
new file mode 100644
index 000000000000..a57e13a65e37
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_sock_addr.c
@@ -0,0 +1,486 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Facebook
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <arpa/inet.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+
+#include <linux/filter.h>
+
+#include <bpf/bpf.h>
+
+#include "cgroup_helpers.h"
+
+#define CG_PATH "/foo"
+
+#define SERV4_IP                "192.168.1.254"
+#define SERV4_REWRITE_IP        "127.0.0.1"
+#define SERV4_PORT              4040
+#define SERV4_REWRITE_PORT      4444
+
+#define SERV6_IP                "face:b00c:1234:5678::abcd"
+#define SERV6_REWRITE_IP        "::1"
+#define SERV6_PORT              6060
+#define SERV6_REWRITE_PORT      6666
+
+#define INET_NTOP_BUF   40
+
+typedef int (*load_fn)(enum bpf_attach_type, const char *comment);
+typedef int (*info_fn)(int, struct sockaddr *, socklen_t *);
+
+struct program {
+        enum bpf_attach_type type;
+        load_fn loadfn;
+        int fd;
+        const char *name;
+        enum bpf_attach_type invalid_type;
+};
+
+char bpf_log_buf[BPF_LOG_BUF_SIZE];
+
+static int mk_sockaddr(int domain, const char *ip, unsigned short port,
+                       struct sockaddr *addr, socklen_t addr_len)
+{
+        struct sockaddr_in6 *addr6;
+        struct sockaddr_in *addr4;
+
+        if (domain != AF_INET && domain != AF_INET6) {
+                log_err("Unsupported address family");
+                return -1;
+        }
+
+        memset(addr, 0, addr_len);
+
+        if (domain == AF_INET) {
+                if (addr_len < sizeof(struct sockaddr_in))
+                        return -1;
+                addr4 = (struct sockaddr_in *)addr;
+                addr4->sin_family = domain;
+                addr4->sin_port = htons(port);
+                if (inet_pton(domain, ip, (void *)&addr4->sin_addr) != 1) {
+                        log_err("Invalid IPv4: %s", ip);
+                        return -1;
+                }
+        } else if (domain == AF_INET6) {
+                if (addr_len < sizeof(struct sockaddr_in6))
+                        return -1;
+                addr6 = (struct sockaddr_in6 *)addr;
+                addr6->sin6_family = domain;
+                addr6->sin6_port = htons(port);
+                if (inet_pton(domain, ip, (void *)&addr6->sin6_addr) != 1) {
+                        log_err("Invalid IPv6: %s", ip);
+                        return -1;
+                }
+        }
+
+        return 0;