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[PATCH v2] module: sign with sha512 instead of sha1 by default

Thorsten Leemhuis posted 1 patch 1 month, 1 week ago 
kernel/module/Kconfig | 1 +
1 file changed, 1 insertion(+)
[PATCH v2] module: sign with sha512 instead of sha1 by default
Posted by Thorsten Leemhuis 1 month, 1 week ago 
Switch away from using sha1 for module signing by default and use the
more modern sha512 instead, which is what among others Arch, Fedora,
RHEL, and Ubuntu are currently using for their kernels.

Sha1 has not been considered secure against well-funded opponents since
2005[1]; since 2011 the NIST and other organizations furthermore
recommended its replacement[2]. This is why OpenSSL on RHEL9, Fedora
Linux 41+[3], and likely some other current and future distributions
reject the creation of sha1 signatures, which leads to a build error of
allmodconfig configurations:

  80A20474797F0000:error:03000098:digital envelope routines:do_sigver_init:invalid digest:crypto/evp/m_sigver.c:342:
  make[4]: *** [.../certs/Makefile:53: certs/signing_key.pem] Error 1
  make[4]: *** Deleting file 'certs/signing_key.pem'
  make[4]: *** Waiting for unfinished jobs....
  make[3]: *** [.../scripts/Makefile.build:478: certs] Error 2
  make[2]: *** [.../Makefile:1936: .] Error 2
  make[1]: *** [.../Makefile:224: __sub-make] Error 2
  make[1]: Leaving directory '...'
  make: *** [Makefile:224: __sub-make] Error 2

This change makes allmodconfig work again and sets a default that is
more appropriate for current and future users, too.

Link: https://www.schneier.com/blog/archives/2005/02/cryptanalysis_o.html [1]
Link: https://csrc.nist.gov/projects/hash-functions [2]
Link: https://fedoraproject.org/wiki/Changes/OpenSSLDistrustsha1SigVer [3]
Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info>
---

v2:
* use 'default MODULE_SIG_SHA512' in the "Hash algorithm to sign
  modules" choice instead of resorting the entries there.
* rewrite patch description
* drop RFC tag

v1: https://lore.kernel.org/all/42aa307d7ffae1851b4a8787f5c276dd0b3beece.1728543368.git.linux@leemhuis.info/
---
 kernel/module/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
index 7c6588148d42d3..0c746a150e34e2 100644
--- a/kernel/module/Kconfig
+++ b/kernel/module/Kconfig
@@ -231,6 +231,7 @@ comment "Do not forget to sign required modules with scripts/sign-file"
 choice
 	prompt "Hash algorithm to sign modules"
 	depends on MODULE_SIG || IMA_APPRAISE_MODSIG
+	default MODULE_SIG_SHA512
 	help
 	  This determines which sort of hashing algorithm will be used during
 	  signature generation.  This algorithm _must_ be built into the kernel

base-commit: d3d1556696c1a993eec54ac585fe5bf677e07474
-- 
2.45.0
Re: [PATCH v2] module: sign with sha512 instead of sha1 by default
Posted by Luis Chamberlain 1 month, 1 week ago 
On Wed, Oct 16, 2024 at 04:18:41PM +0200, Thorsten Leemhuis wrote:
> Switch away from using sha1 for module signing by default and use the
> more modern sha512 instead, which is what among others Arch, Fedora,
> RHEL, and Ubuntu are currently using for their kernels.
> 
> Sha1 has not been considered secure against well-funded opponents since
> 2005[1]; since 2011 the NIST and other organizations furthermore
> recommended its replacement[2]. This is why OpenSSL on RHEL9, Fedora
> Linux 41+[3], and likely some other current and future distributions
> reject the creation of sha1 signatures, which leads to a build error of
> allmodconfig configurations:
> 
>   80A20474797F0000:error:03000098:digital envelope routines:do_sigver_init:invalid digest:crypto/evp/m_sigver.c:342:
>   make[4]: *** [.../certs/Makefile:53: certs/signing_key.pem] Error 1
>   make[4]: *** Deleting file 'certs/signing_key.pem'
>   make[4]: *** Waiting for unfinished jobs....
>   make[3]: *** [.../scripts/Makefile.build:478: certs] Error 2
>   make[2]: *** [.../Makefile:1936: .] Error 2
>   make[1]: *** [.../Makefile:224: __sub-make] Error 2
>   make[1]: Leaving directory '...'
>   make: *** [Makefile:224: __sub-make] Error 2
> 
> This change makes allmodconfig work again and sets a default that is
> more appropriate for current and future users, too.
> 
> Link: https://www.schneier.com/blog/archives/2005/02/cryptanalysis_o.html [1]
> Link: https://csrc.nist.gov/projects/hash-functions [2]
> Link: https://fedoraproject.org/wiki/Changes/OpenSSLDistrustsha1SigVer [3]
> Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info>

Thanks!

Tested-by: kdevops <kdevops@lists.linux.dev> [0]
Links: https://github.com/linux-kdevops/linux-modules-kpd/actions/runs/11420092929/job/31775404330 # [0]

Applied and pushed!

  Luis
Re: [PATCH v2] module: sign with sha512 instead of sha1 by default
Posted by Sami Tolvanen 1 month, 1 week ago 
Hi Thorsten,

On Wed, Oct 16, 2024 at 7:18 AM Thorsten Leemhuis <linux@leemhuis.info> wrote:
>
> Switch away from using sha1 for module signing by default and use the
> more modern sha512 instead, which is what among others Arch, Fedora,
> RHEL, and Ubuntu are currently using for their kernels.
>
> Sha1 has not been considered secure against well-funded opponents since
> 2005[1]; since 2011 the NIST and other organizations furthermore
> recommended its replacement[2]. This is why OpenSSL on RHEL9, Fedora
> Linux 41+[3], and likely some other current and future distributions
> reject the creation of sha1 signatures, which leads to a build error of
> allmodconfig configurations:
>
>   80A20474797F0000:error:03000098:digital envelope routines:do_sigver_init:invalid digest:crypto/evp/m_sigver.c:342:
>   make[4]: *** [.../certs/Makefile:53: certs/signing_key.pem] Error 1
>   make[4]: *** Deleting file 'certs/signing_key.pem'
>   make[4]: *** Waiting for unfinished jobs....
>   make[3]: *** [.../scripts/Makefile.build:478: certs] Error 2
>   make[2]: *** [.../Makefile:1936: .] Error 2
>   make[1]: *** [.../Makefile:224: __sub-make] Error 2
>   make[1]: Leaving directory '...'
>   make: *** [Makefile:224: __sub-make] Error 2
>
> This change makes allmodconfig work again and sets a default that is
> more appropriate for current and future users, too.
>
> Link: https://www.schneier.com/blog/archives/2005/02/cryptanalysis_o.html [1]
> Link: https://csrc.nist.gov/projects/hash-functions [2]
> Link: https://fedoraproject.org/wiki/Changes/OpenSSLDistrustsha1SigVer [3]
> Signed-off-by: Thorsten Leemhuis <linux@leemhuis.info>
> ---
>
> v2:
> * use 'default MODULE_SIG_SHA512' in the "Hash algorithm to sign
>   modules" choice instead of resorting the entries there.
> * rewrite patch description
> * drop RFC tag
>
> v1: https://lore.kernel.org/all/42aa307d7ffae1851b4a8787f5c276dd0b3beece.1728543368.git.linux@leemhuis.info/
> ---
>  kernel/module/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
> index 7c6588148d42d3..0c746a150e34e2 100644
> --- a/kernel/module/Kconfig
> +++ b/kernel/module/Kconfig
> @@ -231,6 +231,7 @@ comment "Do not forget to sign required modules with scripts/sign-file"
>  choice
>         prompt "Hash algorithm to sign modules"
>         depends on MODULE_SIG || IMA_APPRAISE_MODSIG
> +       default MODULE_SIG_SHA512
>         help
>           This determines which sort of hashing algorithm will be used during
>           signature generation.  This algorithm _must_ be built into the kernel

This looks good to me. Thank you for the patch!

Reviewed-by: Sami Tolvanen <samitolvanen@google.com>

Sami

Patchew 2.1-devel-b67e4c2

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