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authorLawrence Brakmo <brakmo@fb.com>2018-01-25 16:14:15 -0800
committerAlexei Starovoitov <ast@kernel.org>2018-01-25 16:41:15 -0800
commitd44874910a26f3a8f81edf873a2473363f07f660 (patch)
tree97438bbc5e9bf77f0cf2bd7f4d8f6eb8f651c605
parentbpf: Add BPF_SOCK_OPS_RETRANS_CB (diff)
downloadlinux-dev-d44874910a26f3a8f81edf873a2473363f07f660.tar.xz
linux-dev-d44874910a26f3a8f81edf873a2473363f07f660.zip
bpf: Add BPF_SOCK_OPS_STATE_CB
Adds support for calling sock_ops BPF program when there is a TCP state change. Two arguments are used; one for the old state and another for the new state. There is a new enum in include/uapi/linux/bpf.h that exports the TCP states that prepends BPF_ to the current TCP state names. If it is ever necessary to change the internal TCP state values (other than adding more to the end), then it will become necessary to convert from the internal TCP state value to the BPF value before calling the BPF sock_ops function. There are a set of compile checks added in tcp.c to detect if the internal and BPF values differ so we can make the necessary fixes. New op: BPF_SOCK_OPS_STATE_CB. Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
-rw-r--r--include/uapi/linux/bpf.h29
-rw-r--r--net/ipv4/tcp.c24
2 files changed, 52 insertions, 1 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 31c93a0bdbc2..db6bdc375126 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1006,7 +1006,8 @@ struct bpf_sock_ops {
/* 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_ALL_CB_FLAGS 0x3 /* Mask of all currently
+#define BPF_SOCK_OPS_STATE_CB_FLAG (1<<2)
+#define BPF_SOCK_OPS_ALL_CB_FLAGS 0x7 /* Mask of all currently
* supported cb flags
*/
@@ -1054,6 +1055,32 @@ enum {
* 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/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 88b62441e7e9..f013ddc191e0 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2042,6 +2042,30 @@ void tcp_set_state(struct sock *sk, int state)
{
int oldstate = sk->sk_state;
+ /* We defined a new enum for TCP states that are exported in BPF
+ * so as not force the internal TCP states to be frozen. The
+ * following checks will detect if an internal state value ever
+ * differs from the BPF value. If this ever happens, then we will
+ * need to remap the internal value to the BPF value before calling
+ * tcp_call_bpf_2arg.
+ */
+ BUILD_BUG_ON((int)BPF_TCP_ESTABLISHED != (int)TCP_ESTABLISHED);
+ BUILD_BUG_ON((int)BPF_TCP_SYN_SENT != (int)TCP_SYN_SENT);
+ BUILD_BUG_ON((int)BPF_TCP_SYN_RECV != (int)TCP_SYN_RECV);
+ BUILD_BUG_ON((int)BPF_TCP_FIN_WAIT1 != (int)TCP_FIN_WAIT1);
+ BUILD_BUG_ON((int)BPF_TCP_FIN_WAIT2 != (int)TCP_FIN_WAIT2);
+ BUILD_BUG_ON((int)BPF_TCP_TIME_WAIT != (int)TCP_TIME_WAIT);
+ BUILD_BUG_ON((int)BPF_TCP_CLOSE != (int)TCP_CLOSE);
+ BUILD_BUG_ON((int)BPF_TCP_CLOSE_WAIT != (int)TCP_CLOSE_WAIT);
+ BUILD_BUG_ON((int)BPF_TCP_LAST_ACK != (int)TCP_LAST_ACK);
+ BUILD_BUG_ON((int)BPF_TCP_LISTEN != (int)TCP_LISTEN);
+ BUILD_BUG_ON((int)BPF_TCP_CLOSING != (int)TCP_CLOSING);
+ BUILD_BUG_ON((int)BPF_TCP_NEW_SYN_RECV != (int)TCP_NEW_SYN_RECV);
+ BUILD_BUG_ON((int)BPF_TCP_MAX_STATES != (int)TCP_MAX_STATES);
+
+ if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_STATE_CB_FLAG))
+ tcp_call_bpf_2arg(sk, BPF_SOCK_OPS_STATE_CB, oldstate, state);
+
switch (state) {
case TCP_ESTABLISHED:
if (oldstate != TCP_ESTABLISHED)