RE: [PATCH bpf-next] bpf: add SO_KEEPALIVE and related options to bpf_setsockopt

From: Eric Dumazet

Sent: 27 May 2020 17:43

On 5/27/20 8:05 AM, Dmitry Yakunin wrote:

quoted

This patch adds support of SO_KEEPALIVE flag and TCP related options
to bpf_setsockopt() routine. This is helpful if we want to enable or tune
TCP keepalive for applications which don't do it in the userspace code.
In order to avoid copy-paste, common code from classic setsockopt was moved
to auxiliary functions in the headers.

Please split this in two patches :
- one adding the helpers, a pure TCP patch.
- one for BPF additions.

...

quoted

diff --git a/net/core/filter.c b/net/core/filter.c
index a6fc234..1035e43 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c

...

quoted

+			case TCP_KEEPIDLE:
+				if (val < 1 || val > MAX_TCP_KEEPIDLE)
+					ret = -EINVAL;
+				else
+					keepalive_time_set(tp, val);
+				break;
+			case TCP_KEEPINTVL:
+				if (val < 1 || val > MAX_TCP_KEEPINTVL)
+					ret = -EINVAL;
+				else
+					tp->keepalive_intvl = val * HZ;
+				break;
+			case TCP_KEEPCNT:
+				if (val < 1 || val > MAX_TCP_KEEPCNT)
+					ret = -EINVAL;
+				else
+					tp->keepalive_probes = val;
+				break;
+			case TCP_SYNCNT:
+				if (val < 1 || val > MAX_TCP_SYNCNT)
+					ret = -EINVAL;
+				else
+					icsk->icsk_syn_retries = val;
+				break;
+			case TCP_USER_TIMEOUT:
+				if (val < 0)
+					ret = -EINVAL;
+				else
+					icsk->icsk_user_timeout = val;
+				break;

It also cannot be right to be layer breaking like this
and directly accessing the protocol socket internals.

At least a kernel_setsockopt() function keeps this separate
and ensures that the socket type is correct.

	David

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