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authorLawrence Brakmo <brakmo@fb.com>2018-01-25 16:14:10 -0800
committerAlexei Starovoitov <ast@kernel.org>2018-01-25 16:41:14 -0800
commitb13d880721729384757f235166068c315326f4a1 (patch)
tree7d117afdbf662f4bc89261885e547053fbed90f7 /include
parentde525be2ca2734865d29c4b67ddd29913b214906 (diff)
bpf: Adds field bpf_sock_ops_cb_flags to tcp_sock
Adds field bpf_sock_ops_cb_flags to tcp_sock and bpf_sock_ops. Its primary use is to determine if there should be calls to sock_ops bpf program at various points in the TCP code. The field is initialized to zero, disabling the calls. A sock_ops BPF program can set it, per connection and as necessary, when the connection is established. It also adds support for reading and writting the field within a sock_ops BPF program. Reading is done by accessing the field directly. However, writing is done through the helper function bpf_sock_ops_cb_flags_set, in order to return an error if a BPF program is trying to set a callback that is not supported in the current kernel (i.e. running an older kernel). The helper function returns 0 if it was able to set all of the bits set in the argument, a positive number containing the bits that could not be set, or -EINVAL if the socket is not a full TCP socket. Examples of where one could call the bpf program: 1) When RTO fires 2) When a packet is retransmitted 3) When the connection terminates 4) When a packet is sent 5) When a packet is received Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/tcp.h11
-rw-r--r--include/uapi/linux/bpf.h17
2 files changed, 27 insertions, 1 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 4f93f0953c41..8f4c54986f97 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -335,6 +335,17 @@ struct tcp_sock {
int linger2;
+
+/* Sock_ops bpf program related variables */
+#ifdef CONFIG_BPF
+ u8 bpf_sock_ops_cb_flags; /* Control calling BPF programs
+ * values defined in uapi/linux/tcp.h
+ */
+#define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) (TP->bpf_sock_ops_cb_flags & ARG)
+#else
+#define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0
+#endif
+
/* Receiver side RTT estimation */
struct {
u32 rtt_us;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 8d5874c2c4ff..aa128407c44d 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -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
@@ -969,8 +978,14 @@ 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 */
};
+/* Definitions for bpf_sock_ops_cb_flags */
+#define BPF_SOCK_OPS_ALL_CB_FLAGS 0 /* Mask of all currently
+ * supported cb flags
+ */
+
/* List of known BPF sock_ops operators.
* New entries can only be added at the end
*/