linux-kernel - Re: [PATCH v2 security-next 1/4] security: Hornet LSM

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Message-ID: <CAFnufp1erGboUtRaqLoKC48c+9jmqzEfFW8W46xt77JMC0PFpQ@mail.gmail.com>
Date: Sat, 12 Apr 2025 02:29:47 +0200
From: Matteo Croce <technoboy85@...il.com>
To: Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc: Blaise Boscaccy <bboscaccy@...ux.microsoft.com>, Jonathan Corbet <corbet@....net>, 
	David Howells <dhowells@...hat.com>, Herbert Xu <herbert@...dor.apana.org.au>, 
	"David S. Miller" <davem@...emloft.net>, Paul Moore <paul@...l-moore.com>, 
	James Morris <jmorris@...ei.org>, "Serge E. Hallyn" <serge@...lyn.com>, 
	Masahiro Yamada <masahiroy@...nel.org>, Nathan Chancellor <nathan@...nel.org>, 
	Nicolas Schier <nicolas@...sle.eu>, Shuah Khan <shuah@...nel.org>, 
	Mickaël Salaün <mic@...ikod.net>, 
	Günther Noack <gnoack@...gle.com>, 
	Nick Desaulniers <nick.desaulniers+lkml@...il.com>, Bill Wendling <morbo@...gle.com>, 
	Justin Stitt <justinstitt@...gle.com>, Jarkko Sakkinen <jarkko@...nel.org>, 
	Jan Stancek <jstancek@...hat.com>, Neal Gompa <neal@...pa.dev>, 
	"open list:DOCUMENTATION" <linux-doc@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>, 
	keyrings@...r.kernel.org, 
	Linux Crypto Mailing List <linux-crypto@...r.kernel.org>, 
	LSM List <linux-security-module@...r.kernel.org>, 
	Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>, 
	"open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@...r.kernel.org>, bpf <bpf@...r.kernel.org>, 
	clang-built-linux <llvm@...ts.linux.dev>, nkapron@...gle.com, 
	Matteo Croce <teknoraver@...a.com>, Roberto Sassu <roberto.sassu@...wei.com>, 
	Cong Wang <xiyou.wangcong@...il.com>
Subject: Re: [PATCH v2 security-next 1/4] security: Hornet LSM

Il giorno sab 12 apr 2025 alle ore 02:19 Alexei Starovoitov
<alexei.starovoitov@...il.com> ha scritto:

Similar to what I proposed here?

https://lore.kernel.org/bpf/20211203191844.69709-2-mcroce@linux.microsoft.com/

> The verification of module signatures is a job of the module loading process.
> The same thing should be done by the bpf system.
> The signature needs to be passed into sys_bpf syscall
> as a part of BPF_PROG_LOAD command.

 static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
 {
@@ -2302,6 +2306,43 @@ static int bpf_prog_load(union bpf_attr *attr,
bpfptr_t uattr)

> It probably should be two new fields in union bpf_attr
> (signature and length),

@@ -1346,6 +1346,8 @@ union bpf_attr {
  __aligned_u64 fd_array; /* array of FDs */
  __aligned_u64 core_relos;
  __u32 core_relo_rec_size; /* sizeof(struct bpf_core_relo) */
+ __aligned_u64 signature; /* instruction's signature */
+ __u32 sig_len; /* signature size */

> and the whole thing should be processed as part of the loading
> with human readable error reported back through the verifier log
> in case of signature mismatch, etc.

+ if (err) {
+ pr_warn("Invalid BPF signature for '%s': %pe\n",
+ prog->aux->name, ERR_PTR(err));
+ goto free_prog_sec;
+ }

It's been four years since my submission and the discussion was
lengthy, what was the problem with the proposed signature in bpf_attr?

Regards,
-- 
Matteo Croce

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