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Message-ID: <20240212154331.19460-1-qde@naccy.de>
Date: Mon, 12 Feb 2024 16:43:28 +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>,
Stephen Hemminger <stephen@...workplumber.org>,
kernel-team@...a.com,
Matthieu Baerts <matttbe@...nel.org>,
Quentin Deslandes <qde@...cy.de>
Subject: [PATCH iproute2 v7 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 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 COL_EXT.
Patch #2 uses libbpf and BTF to pretty print the map's content, like
`bpftool map dump` would do.
Patch #3 updates ss' man page to explain new options.
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,
},
}
]
Changed this series to an RFC as the merging window for net-next is
closed.
Changes from v6:
* Remove column dedicated to BPF socket-local storage (COL_SKSTOR),
use COL_EXT instead (Matthieu).
Changes from v5:
* Add support for --oneline when printing socket-local data.
* Use \t to indent instead of " " to be consistent with other columns.
* Removed Martin's ack on patch #2 due to amount of lines changed.
Changes from v4:
* Fix return code for 2 calls.
* Fix issue when inet_show_netlink() retries a request.
* BPF dump object is created in bpf_map_opts_load_info().
Changes from v3:
* Minor refactoring to reduce number of HAVE_LIBBF usage.
* Update ss' man page.
* btf_dump structure created to print the socket-local data is cached
in bpf_map_opts. Creation of the btf_dump structure is performed if
needed, before printing the data.
* If a map can't be pretty-printed, print its ID and a message instead
of skipping it.
* If show_all=true, send an empty message to the kernel to retrieve all
the maps (as Martin suggested).
Changes from v2:
* bpf_map_opts_is_enabled is not inline anymore.
* Add more #ifdef HAVE_LIBBPF to prevent compilation error if
libbpf support is disabled.
* Fix erroneous usage of args instead of _args in vout().
* Add missing btf__free() and close(fd).
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 (3):
ss: add support for BPF socket-local storage
ss: pretty-print BPF socket-local storage
ss: update man page to document --bpf-maps and --bpf-map-id=
man/man8/ss.8 | 6 +
misc/ss.c | 399 ++++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 396 insertions(+), 9 deletions(-)
--
2.43.0
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