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From: Hangbin Liu <haliu@redhat.com>
To: Martynas Pumputis <m@lambda.lt>
Cc: netdev@vger.kernel.org, stephen@networkplumber.org, dsahern@gmail.com
Subject: Re: [PATCH iproute2] libbpf: fix attach of prog with multiple sections
Date: Tue, 6 Jul 2021 10:44:55 +0800 [thread overview]
Message-ID: <YOPDp/UqkbX8DM2+@fedora> (raw)
In-Reply-To: <20210705124307.201303-1-m@lambda.lt>
On Mon, Jul 05, 2021 at 02:43:07PM +0200, Martynas Pumputis wrote:
> When BPF programs which consists of multiple executable sections via
> iproute2+libbpf (configured with LIBBPF_FORCE=on), we noticed that a
> wrong section can be attached to a device. E.g.:
>
> # tc qdisc replace dev lxc_health clsact
> # tc filter replace dev lxc_health ingress prio 1 \
> handle 1 bpf da obj bpf_lxc.o sec from-container
> # tc filter show dev lxc_health ingress filter protocol all
> pref 1 bpf chain 0 filter protocol all pref 1 bpf chain 0
> handle 0x1 bpf_lxc.o:[__send_drop_notify] <-- WRONG SECTION
> direct-action not_in_hw id 38 tag 7d891814eda6809e jited
>
> After taking a closer look into load_bpf_object() in lib/bpf_libbpf.c,
> we noticed that the filter used in the program iterator does not check
> whether a program section name matches a requested section name
> (cfg->section). This can lead to a wrong prog FD being used to attach
> the program.
>
> Fixes: 6d61a2b55799 ("lib: add libbpf support")
> Signed-off-by: Martynas Pumputis <m@lambda.lt>
> ---
> lib/bpf_libbpf.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/lib/bpf_libbpf.c b/lib/bpf_libbpf.c
> index d05737a4..f76b90d2 100644
> --- a/lib/bpf_libbpf.c
> +++ b/lib/bpf_libbpf.c
> @@ -267,10 +267,12 @@ static int load_bpf_object(struct bpf_cfg_in *cfg)
> }
>
> bpf_object__for_each_program(p, obj) {
> + bool prog_to_attach = !prog && cfg->section &&
> + !strcmp(get_bpf_program__section_name(p), cfg->section);
> +
> /* Only load the programs that will either be subsequently
> * attached or inserted into a tail call map */
> - if (find_legacy_tail_calls(p, obj) < 0 && cfg->section &&
> - strcmp(get_bpf_program__section_name(p), cfg->section)) {
> + if (find_legacy_tail_calls(p, obj) < 0 && !prog_to_attach) {
> ret = bpf_program__set_autoload(p, false);
> if (ret)
> return -EINVAL;
> @@ -279,7 +281,8 @@ static int load_bpf_object(struct bpf_cfg_in *cfg)
>
> bpf_program__set_type(p, cfg->type);
> bpf_program__set_ifindex(p, cfg->ifindex);
> - if (!prog)
> +
> + if (prog_to_attach)
> prog = p;
> }
>
> --
> 2.32.0
>
Thanks for the fix.
Acked-by: Hangbin Liu <haliu@redhat.com>
next prev parent reply other threads:[~2021-07-06 2:45 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-05 12:43 Martynas Pumputis
2021-07-06 2:44 ` Hangbin Liu [this message]
2021-07-20 20:27 ` Andrii Nakryiko
2021-07-21 14:47 ` Martynas Pumputis
2021-07-21 14:59 ` David Ahern
2021-07-21 15:27 ` Martynas Pumputis
2021-07-23 4:01 ` Andrii Nakryiko
2021-07-23 4:41 ` Hangbin Liu
2021-07-23 4:51 ` Andrii Nakryiko
2021-07-23 7:55 ` Hangbin Liu
2021-07-23 16:09 ` Andrii Nakryiko
2021-07-24 8:12 ` Hangbin Liu
2021-07-24 0:12 ` David Ahern
2021-07-24 0:25 ` Andrii Nakryiko
2021-07-26 13:58 ` David Ahern
2021-07-26 15:13 ` Andrii Nakryiko
2021-07-27 2:51 ` David Ahern
2021-07-27 19:05 ` Andrii Nakryiko
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