netdev - Re: [PATCH bpf-next v3 4/5] libbpf: fix error when st-prefix

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20250108134527.GA86266@j66a10360.sqa.eu95>
Date: Wed, 8 Jan 2025 21:45:27 +0800
From: "D. Wythe" <alibuda@...ux.alibaba.com    >
To: Martin KaFai Lau <martin.lau@...ux.dev>
Cc: "D. Wythe" <alibuda@...ux.alibaba.com>, kgraul@...ux.ibm.com,
	wenjia@...ux.ibm.com, jaka@...ux.ibm.com, ast@...nel.org,
	daniel@...earbox.net, andrii@...nel.org, pabeni@...hat.com,
	song@...nel.org, sdf@...gle.com, haoluo@...gle.com, yhs@...com,
	edumazet@...gle.com, john.fastabend@...il.com, kpsingh@...nel.org,
	jolsa@...nel.org, guwen@...ux.alibaba.com, kuba@...nel.org,
	davem@...emloft.net, netdev@...r.kernel.org,
	linux-s390@...r.kernel.org, linux-rdma@...r.kernel.org,
	bpf@...r.kernel.org, Daniel Xu <dlxu@...a.com>
Subject: Re: [PATCH bpf-next v3 4/5] libbpf: fix error when st-prefix_ops and
 ops from differ btf

On Tue, Jan 07, 2025 at 03:24:51PM -0800, Martin KaFai Lau wrote:
> On 12/22/24 6:10 PM, D. Wythe wrote:
> >On Thu, Dec 19, 2024 at 02:43:30PM -0800, Martin KaFai Lau wrote:
> >>On 12/17/24 6:44 PM, D. Wythe wrote:
> >>>Here are four possible case:
> >>>
> >>>+--------+-------------+-------------+---------------------------------+
> >>>|        | st_opx_xxx  | xxx         |                                 |
> >>>+--------+-------------+-------------+---------------------------------+
> >>>| case 0 | btf_vmlinux | bft_vmlinux | be used and reg only in vmlinux |
> >>>+--------+-------------+-------------+---------------------------------+
> >>>| case 1 | btf_vmlinux | bpf_mod     | INVALID                         |
> >>>+--------+-------------+-------------+---------------------------------+
> >>>| case 2 | btf_mod     | btf_vmlinux | reg in mod but be used both in  |
> >>>|        |             |             | vmlinux and mod.                |
> >>>+--------+-------------+-------------+---------------------------------+
> >>>| case 3 | btf_mod     | btf_mod     | be used and reg only in mod     |
> >>>+--------+-------------+-------------+---------------------------------+
> >>>
> >>>At present, cases 0, 1, and 3 can be correctly identified, because
> >>>st_ops_xxx is searched from the same btf with xxx. In order to
> >>>handle case 2 correctly without affecting other cases, we cannot simply
> >>>change the search method for st_ops_xxx from find_btf_by_prefix_kind()
> >>>to find_ksym_btf_id(), because in this way, case 1 will not be
> >>>recognized anymore.
> >>>  	snprintf(tname, sizeof(tname), "%.*s",
> >>>@@ -1020,17 +1021,25 @@ find_struct_ops_kern_types(struct bpf_object *obj, const char *tname_raw,
> >>>  	}
> >>>  	kern_type = btf__type_by_id(btf, kern_type_id);
> >>>+	ret = snprintf(stname, sizeof(stname), "%s%s", STRUCT_OPS_VALUE_PREFIX, tname);
> >>
> >>How about always look for "struct bpf_struct_ops_smc_ops" first,
> >>figure out the btf, and then look for "struct smc_ops", would it
> >>work?
> >
> >I think this might not work, as the core issue lies in the fact that
> >bpf_struct_ops_smc_ops and smc_ops are located on different btf.
> >Searching for one fisrt cannot lead to the inference of the other.
> 
> Take a look at btf_find_by_name_kind(btf, 1 /* from base_btf */,
> ...) and also btf_type_by_id(). It starts searching from the
> btf->base_btf which should be the btf_vmlinux here and should have
> the "struct smc_ops". Please try.

Got it, I will try it, thanks for your suggestion.

D. Wythe