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Message-ID: <20231208145720.411075-1-qde@naccy.de>
Date: Fri, 8 Dec 2023 15:57:18 +0100
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>, <kernel-team@...a.com>
Subject: [PATCH v2 0/2] 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 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 #2 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 340116 0 [...]
map_id: 114 [
(struct my_sk_storage){
.field_hh = (char)3,
(union){
.a = (int)17,
.b = (int)17,
},
}
]
Changes from v1:
* Remove the first patch from the series (fix) and submit it separately.
* Remove double allocation of struct rtattr.
* Close BPF map FDs on exit.
* If bpf_map_get_fd_by_id() fails with ENOENT, print an error message
and continue to the next map ID.
* Fix typo in new command line option documentation.
* Only use bpf_map_info.btf_value_type_id and ignore
bpf_map_info.btf_vmlinux_value_type_id (unused for socket-local storage).
* Use btf_dump__dump_type_data() instead of manually using BTF to
pretty-print socket-local storage data. This change alone divides the size
of the patch series by 2.
Quentin Deslandes (2):
ss: add support for BPF socket-local storage
ss: pretty-print BPF socket-local storage
misc/ss.c | 433 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 425 insertions(+), 8 deletions(-)
--
2.43.0
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