From: Jason Xing <kerneljasonxing@xxxxxxxxx>
Date: Thu, 13 Feb 2025 08:43:53 +0800
> Support bpf_setsockopt() to set the maximum value of RTO for
> BPF program.
>
> Signed-off-by: Jason Xing <kerneljasonxing@xxxxxxxxx>
> ---
> Documentation/networking/ip-sysctl.rst | 3 ++-
> include/uapi/linux/bpf.h | 2 ++
> net/core/filter.c | 6 ++++++
> tools/include/uapi/linux/bpf.h | 2 ++
> 4 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
> index 054561f8dcae..78eb0959438a 100644
> --- a/Documentation/networking/ip-sysctl.rst
> +++ b/Documentation/networking/ip-sysctl.rst
> @@ -1241,7 +1241,8 @@ tcp_rto_min_us - INTEGER
>
> tcp_rto_max_ms - INTEGER
> Maximal TCP retransmission timeout (in ms).
> - Note that TCP_RTO_MAX_MS socket option has higher precedence.
> + Note that TCP_BPF_RTO_MAX and TCP_RTO_MAX_MS socket option have the
> + higher precedence for configuring this setting.
>
> When changing tcp_rto_max_ms, it is important to understand
> that tcp_retries2 might need a change.
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 2acf9b336371..8ab6ef144217 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -2868,6 +2868,7 @@ union bpf_attr {
> * **TCP_NODELAY**, **TCP_MAXSEG**, **TCP_WINDOW_CLAMP**,
> * **TCP_THIN_LINEAR_TIMEOUTS**, **TCP_BPF_DELACK_MAX**,
> * **TCP_BPF_RTO_MIN**, **TCP_BPF_SOCK_OPS_CB_FLAGS**.
> + * **TCP_BPF_RTO_MAX**
> * * **IPPROTO_IP**, which supports *optname* **IP_TOS**.
> * * **IPPROTO_IPV6**, which supports the following *optname*\ s:
> * **IPV6_TCLASS**, **IPV6_AUTOFLOWLABEL**.
> @@ -7091,6 +7092,7 @@ enum {
> TCP_BPF_SYN_IP = 1006, /* Copy the IP[46] and TCP header */
> TCP_BPF_SYN_MAC = 1007, /* Copy the MAC, IP[46], and TCP header */
> TCP_BPF_SOCK_OPS_CB_FLAGS = 1008, /* Get or Set TCP sock ops flags */
> + TCP_BPF_RTO_MAX = 1009, /* Max delay ack in msecs */
> };
>
> enum {
> diff --git a/net/core/filter.c b/net/core/filter.c
> index 2ec162dd83c4..a21a147e0a86 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -5303,6 +5303,12 @@ static int bpf_sol_tcp_setsockopt(struct sock *sk, int optname,
> return -EINVAL;
> tp->bpf_sock_ops_cb_flags = val;
> break;
> + case TCP_BPF_RTO_MAX:
> + if (val > TCP_RTO_MAX_SEC * MSEC_PER_SEC ||
> + val < TCP_RTO_MAX_MIN_SEC * MSEC_PER_SEC)
> + return -EINVAL;
> + inet_csk(sk)->icsk_rto_max = msecs_to_jiffies(val);
> + break;
> default:
> return -EINVAL;
> }
You need not define TCP_BPF_RTO_MAX because TCP_RTO_MAX is not a
BPF specific option, and you can just reuse do_tcp_setsockopt(),
then bpf_getsockopt() also works.
---8<---
diff --git a/net/core/filter.c b/net/core/filter.c
index 2ec162dd83c4..77732f10097c 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5382,6 +5382,7 @@ static int sol_tcp_sockopt(struct sock *sk, int optname,
case TCP_USER_TIMEOUT:
case TCP_NOTSENT_LOWAT:
case TCP_SAVE_SYN:
+ case TCP_RTO_MAX:
if (*optlen != sizeof(int))
return -EINVAL;
break;
---8<---
