bpf: Add access to snd_cwnd and others in sock_ops
Adds read access to snd_cwnd and srtt_us fields of tcp_sock. Since these
fields are only valid if the socket associated with the sock_ops program
call is a full socket, the field is_fullsock is also added to the
bpf_sock_ops struct. If the socket is not a full socket, reading these
fields returns 0.
Note that in most cases it will not be necessary to check is_fullsock to
know if there is a full socket. The context of the call, as specified by
the 'op' field, can sometimes determine whether there is a full socket.
The struct bpf_sock_ops has the following fields added:
__u32 is_fullsock; /* Some TCP fields are only valid if
* there is a full socket. If not, the
* fields read as zero.
*/
__u32 snd_cwnd;
__u32 srtt_us; /* Averaged RTT << 3 in usecs */
There is a new macro, SOCK_OPS_GET_TCP32(NAME), to make it easier to add
read access to more 32 bit tcp_sock fields.
Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 80b5b48..0062302 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -985,6 +985,7 @@ struct bpf_sock_ops_kern {
u32 reply;
u32 replylong[4];
};
+ u32 is_fullsock;
};
#endif /* __LINUX_FILTER_H__ */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 4e09398..89a6560 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -2012,10 +2012,12 @@ static inline int tcp_call_bpf(struct sock *sk, int op)
struct bpf_sock_ops_kern sock_ops;
int ret;
- if (sk_fullsock(sk))
- sock_owned_by_me(sk);
-
memset(&sock_ops, 0, sizeof(sock_ops));
+ if (sk_fullsock(sk)) {
+ sock_ops.is_fullsock = 1;
+ sock_owned_by_me(sk);
+ }
+
sock_ops.sk = sk;
sock_ops.op = op;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 4c223ab..80d62e8 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -941,6 +941,12 @@ struct bpf_sock_ops {
__u32 local_ip6[4]; /* Stored in network byte order */
__u32 remote_port; /* Stored in network byte order */
__u32 local_port; /* stored in host byte order */
+ __u32 is_fullsock; /* Some TCP fields are only valid if
+ * there is a full socket. If not, the
+ * fields read as zero.
+ */
+ __u32 snd_cwnd;
+ __u32 srtt_us; /* Averaged RTT << 3 in usecs */
};
/* List of known BPF sock_ops operators.