linux-hardening - Re: [PATCH] ima: Add __counted_by for struct modsig and use struct

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Message-ID: <3117d99434303b00f5057bfbe4615cf8cd26b72a.camel@linux.ibm.com>
Date: Wed, 18 Oct 2023 14:16:18 -0400
From: Mimi Zohar <zohar@...ux.ibm.com>
To: "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Dmitry Kasatkin
 <dmitry.kasatkin@...il.com>,
        Paul Moore <paul@...l-moore.com>, James Morris
 <jmorris@...ei.org>,
        "Serge E. Hallyn" <serge@...lyn.com>
Cc: linux-integrity@...r.kernel.org, linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] ima: Add __counted_by for struct modsig and use
 struct_size()

On Mon, 2023-10-09 at 13:52 -0600, Gustavo A. R. Silva wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for
> array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> Also, relocate `hdr->raw_pkcs7_len = sig_len;` so that the __counted_by
> annotation has effect, and flex-array member `raw_pkcs7` can be properly
> bounds-checked at run-time.
> 
> While there, use struct_size() helper, instead of the open-coded
> version, to calculate the size for the allocation of the whole
> flexible structure, including of course, the flexible-array member.
> 
> This code was found with the help of Coccinelle, and audited and
> fixed manually.
> 
> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>

Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>