bpf: add selftest for tcpbpf

Added a selftest for tcpbpf (sock_ops) that checks that the appropriate
callbacks occured and that it can access tcp_sock fields and that their
values are correct.

Run with command: ./test_tcpbpf_user
Adding the flag "-d" will show why it did not pass.

Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

8 files changed, 480 insertions, 6 deletions

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index af1f49ad8b88..db6bdc375126 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -17,7 +17,7 @@
 #define BPF_ALU64       0x07    /* alu mode in double word width */
 
 /* ld/ldx fields */
-#define BPF_DW          0x18    /* double word */
+#define BPF_DW          0x18    /* double word (64-bit) */
 #define BPF_XADD        0xc0    /* exclusive add */
 
 /* alu/jmp fields */
@@ -642,6 +642,14 @@ union bpf_attr {
  *     @optlen: length of optval in bytes
  *     Return: 0 or negative error
  *
+ * int bpf_sock_ops_cb_flags_set(bpf_sock_ops, flags)
+ *     Set callback flags for sock_ops
+ *     @bpf_sock_ops: pointer to bpf_sock_ops_kern struct
+ *     @flags: flags value
+ *     Return: 0 for no error
+ *             -EINVAL if there is no full tcp socket
+ *             bits in flags that are not supported by current kernel
+ *
  * int bpf_skb_adjust_room(skb, len_diff, mode, flags)
  *     Grow or shrink room in sk_buff.
  *     @skb: pointer to skb
@@ -748,7 +756,8 @@ union bpf_attr {
         FN(perf_event_read_value),      \
         FN(perf_prog_read_value),       \
         FN(getsockopt),                 \
-        FN(override_return),
+        FN(override_return),            \
+        FN(sock_ops_cb_flags_set),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call
@@ -952,8 +961,9 @@ struct bpf_map_info {
 struct bpf_sock_ops {
         __u32 op;
         union {
-                __u32 reply;
-                __u32 replylong[4];
+                __u32 args[4];          /* Optionally passed to bpf program */
+                __u32 reply;            /* Returned by bpf program          */
+                __u32 replylong[4];     /* Optionally returned by bpf prog  */
         };
         __u32 family;
         __u32 remote_ip4;       /* Stored in network byte order */
@@ -968,8 +978,39 @@ struct bpf_sock_ops {
                                  */
         __u32 snd_cwnd;
         __u32 srtt_us;          /* Averaged RTT << 3 in usecs */
+        __u32 bpf_sock_ops_cb_flags; /* flags defined in uapi/linux/tcp.h */
+        __u32 state;
+        __u32 rtt_min;
+        __u32 snd_ssthresh;
+        __u32 rcv_nxt;
+        __u32 snd_nxt;
+        __u32 snd_una;
+        __u32 mss_cache;
+        __u32 ecn_flags;
+        __u32 rate_delivered;
+        __u32 rate_interval_us;
+        __u32 packets_out;
+        __u32 retrans_out;
+        __u32 total_retrans;
+        __u32 segs_in;
+        __u32 data_segs_in;
+        __u32 segs_out;
+        __u32 data_segs_out;
+        __u32 lost_out;
+        __u32 sacked_out;
+        __u32 sk_txhash;
+        __u64 bytes_received;
+        __u64 bytes_acked;
 };
 
+/* Definitions for bpf_sock_ops_cb_flags */
+#define BPF_SOCK_OPS_RTO_CB_FLAG        (1<<0)
+#define BPF_SOCK_OPS_RETRANS_CB_FLAG    (1<<1)
+#define BPF_SOCK_OPS_STATE_CB_FLAG      (1<<2)
+#define BPF_SOCK_OPS_ALL_CB_FLAGS       0x7             /* Mask of all currently
+                                                         * supported cb flags
+                                                         */
+
 /* List of known BPF sock_ops operators.
  * New entries can only be added at the end
  */
@@ -1003,6 +1044,43 @@ enum {
                                          * a congestion threshold. RTTs above
                                          * this indicate congestion
                                          */
+        BPF_SOCK_OPS_RTO_CB,            /* Called when an RTO has triggered.
+                                         * Arg1: value of icsk_retransmits
+                                         * Arg2: value of icsk_rto
+                                         * Arg3: whether RTO has expired
+                                         */
+        BPF_SOCK_OPS_RETRANS_CB,        /* Called when skb is retransmitted.
+                                         * Arg1: sequence number of 1st byte
+                                         * Arg2: # segments
+                                         * Arg3: return value of
+                                         *       tcp_transmit_skb (0 => success)
+                                         */
+        BPF_SOCK_OPS_STATE_CB,          /* Called when TCP changes state.
+                                         * Arg1: old_state
+                                         * Arg2: new_state
+                                         */
+};
+
+/* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
+ * changes between the TCP and BPF versions. Ideally this should never happen.
+ * If it does, we need to add code to convert them before calling
+ * the BPF sock_ops function.
+ */
+enum {
+        BPF_TCP_ESTABLISHED = 1,
+        BPF_TCP_SYN_SENT,
+        BPF_TCP_SYN_RECV,
+        BPF_TCP_FIN_WAIT1,
+        BPF_TCP_FIN_WAIT2,
+        BPF_TCP_TIME_WAIT,
+        BPF_TCP_CLOSE,
+        BPF_TCP_CLOSE_WAIT,
+        BPF_TCP_LAST_ACK,
+        BPF_TCP_LISTEN,
+        BPF_TCP_CLOSING,        /* Now a valid state */
+        BPF_TCP_NEW_SYN_RECV,
+
+        BPF_TCP_MAX_STATES      /* Leave at the end! */
 };
 
 #define TCP_BPF_IW              1001    /* Set TCP initial congestion window */
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 3a44b655d852..98688352208b 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -14,13 +14,13 @@ CFLAGS += -Wall -O2 -I$(APIDIR) -I$(LIBDIR) -I$(GENDIR) $(GENFLAGS) -I../../../i
 LDLIBS += -lcap -lelf -lrt
 
 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_align test_verifier_log test_dev_cgroup test_tcpbpf_user
 
 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     \
         sockmap_verdict_prog.o dev_cgroup.o sample_ret0.o test_tracepoint.o \
         test_l4lb_noinline.o test_xdp_noinline.o test_stacktrace_map.o \
-        sample_map_ret0.o
+        sample_map_ret0.o test_tcpbpf_kern.o
 
 TEST_PROGS := test_kmod.sh test_xdp_redirect.sh test_xdp_meta.sh \
         test_offload.py
diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index 33cb00e46c49..dde2c11d7771 100644
--- a/tools/testing/selftests/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h
@@ -71,6 +71,8 @@ static int (*bpf_setsockopt)(void *ctx, int level, int optname, void *optval,
 static int (*bpf_getsockopt)(void *ctx, int level, int optname, void *optval,
                              int optlen) =
         (void *) BPF_FUNC_getsockopt;
+static int (*bpf_sock_ops_cb_flags_set)(void *ctx, int flags) =
+        (void *) BPF_FUNC_sock_ops_cb_flags_set;
 static int (*bpf_sk_redirect_map)(void *ctx, void *map, int key, int flags) =
         (void *) BPF_FUNC_sk_redirect_map;
 static int (*bpf_sock_map_update)(void *map, void *key, void *value,
diff --git a/tools/testing/selftests/bpf/tcp_client.py b/tools/testing/selftests/bpf/tcp_client.py
new file mode 100755
index 000000000000..481dccdf140c
--- /dev/null
+++ b/tools/testing/selftests/bpf/tcp_client.py
@@ -0,0 +1,51 @@