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Message-ID: <20231027121155.1244308-1-qde@naccy.de>
Date: Fri, 27 Oct 2023 14:11:52 +0200
From: Quentin Deslandes <qde@...cy.de>
To: <netdev@...r.kernel.org>
CC: David Ahern <dsahern@...il.com>, Martin KaFai Lau <martin.lau@...nel.org>,
Quentin Deslandes <qde@...cy.de>
Subject: [RFC PATCH 0/3] ss: pretty-printing BPF socket-local storage
BPF allows programs to store socket-specific data using
BPF_MAP_TYPE_SK_STORAGE maps. The data is attached to the socket itself,
and Martin added INET_DIAG_REQ_SK_BPF_STORAGES, so it can be fetched
using the INET_DIAG mechanism.
Currently, ss doesn't request the socket-local data, this patch aims to
fix this.
The first patch fixes a bug where the "Process" column would always be
printed on ss' output, even if --processes/-p is not used.
Patch #2 requests the socket-local data for the requested map ID
(--bpf-map-id=) or all the maps (--bpf-maps). It then prints the map_id
in a dedicated column.
Patch #3 uses libbpf and BTF to pretty print the map's content, like
`bpftool map dump` would do.
While I think it makes sense for ss to provide the socket-local storage
content for the sockets, it's difficult to conciliate the column-based
output of ss and having readable socket-local data. Hence, the
socket-local data is printed in a readable fashion over multiple lines
under its socket statistics, independently of the column-based approach.
Here is an example of ss' output with --bpf-maps:
[...]
ESTAB 2960280 0 [...]
map_id: 259 [
(struct my_sk_storage) {
.field_hh = (char)127,
.<anon> = (union <anon>) {
.a = (int)0,
.b = (int)0,
},
},
]
Quentin Deslandes (3):
ss: prevent "Process" column from being printed unless requested
ss: add support for BPF socket-local storage
ss: pretty-print BPF socket-local storage
misc/ss.c | 822 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 818 insertions(+), 4 deletions(-)
--
2.41.0
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