[PATCH 0/2] module: Split modules_install compression and in-kernel decompression

[PATCH 0/2] module: Split modules_install compression and in-kernel decompression

[Petr Pavlu]

Allow enabling the in-kernel module decompression support separately,
without requiring to enable also the automatic compression during
'make modules_install'.

Petr Pavlu (2):
  module: Split modules_install compression and in-kernel decompression
  module: Clean up the description of MODULE_SIG_<type>

 kernel/module/Kconfig    | 77 ++++++++++++++++++++--------------------
 scripts/Makefile.modinst |  2 ++
 2 files changed, 41 insertions(+), 38 deletions(-)


base-commit: 933069701c1b507825b514317d4edd5d3fd9d417
-- 
2.35.3

[PATCH 1/2] module: Split modules_install compression and in-kernel decompression

[Petr Pavlu]

The kernel configuration allows specifying a module compression mode. If
one is selected then each module gets compressed during
'make modules_install' and additionally one can also enable support for
a respective direct in-kernel decompression support. This means that the
decompression support cannot be enabled without the automatic compression.

Some distributions, such as the (open)SUSE family, use a signer service for
modules. A build runs on a worker machine but signing is done by a separate
locked-down server that is in possession of the signing key. The build
invokes 'make modules_install' to create a modules tree, collects
information about the modules, asks the signer service for their signature,
appends each signature to the respective module and compresses all modules.

When using this arrangment, the 'make modules_install' step produces
unsigned+uncompressed modules and the distribution's own build recipe takes
care of signing and compression later.

The signing support can be currently enabled without automatically signing
modules during 'make modules_install'. However, the in-kernel decompression
support can be selected only after first enabling automatic compression
during this step.

To allow only enabling the in-kernel decompression support without the
automatic compression during 'make modules_install', separate the
compression options similarly to the signing options, as follows:

> Enable loadable module support
[*] Module compression
      Module compression type (GZIP)  --->
[*]   Automatically compress all modules
[ ]   Support in-kernel module decompression

* "Module compression" (MODULE_COMPRESS) is a new main switch for the
  compression/decompression support. It replaces MODULE_COMPRESS_NONE.
* "Module compression type" (MODULE_COMPRESS_<type>) chooses the
  compression type, one of GZ, XZ, ZSTD.
* "Automatically compress all modules" (MODULE_COMPRESS_ALL) is a new
  option to enable module compression during 'make modules_install'. It
  defaults to Y.
* "Support in-kernel module decompression" (MODULE_DECOMPRESS) enables
  in-kernel decompression.

Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
---
 kernel/module/Kconfig    | 61 ++++++++++++++++++++--------------------
 scripts/Makefile.modinst |  2 ++
 2 files changed, 33 insertions(+), 30 deletions(-)

diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
index 4047b6d48255..bb7f7930fef6 100644
--- a/kernel/module/Kconfig
+++ b/kernel/module/Kconfig
@@ -278,64 +278,65 @@ config MODULE_SIG_HASH
 	default "sha3-384" if MODULE_SIG_SHA3_384
 	default "sha3-512" if MODULE_SIG_SHA3_512
 
-choice
-	prompt "Module compression mode"
+config MODULE_COMPRESS
+	bool "Module compression"
 	help
-	  This option allows you to choose the algorithm which will be used to
-	  compress modules when 'make modules_install' is run. (or, you can
-	  choose to not compress modules at all.)
-
-	  External modules will also be compressed in the same way during the
-	  installation.
-
-	  For modules inside an initrd or initramfs, it's more efficient to
-	  compress the whole initrd or initramfs instead.
-
+	  Enable module compression to reduce on-disk size of module binaries.
 	  This is fully compatible with signed modules.
 
-	  Please note that the tool used to load modules needs to support the
-	  corresponding algorithm. module-init-tools MAY support gzip, and kmod
-	  MAY support gzip, xz and zstd.
+	  The tool used to work with modules needs to support the selected
+	  compression type. kmod MAY support gzip, xz and zstd. Other tools
+	  might have a limited selection of the supported types.
 
-	  Your build system needs to provide the appropriate compression tool
-	  to compress the modules.
+	  Note that for modules inside an initrd or initramfs, it's more
+	  efficient to compress the whole ramdisk instead.
 
-	  If in doubt, select 'None'.
+	  If unsure, say N.
 
-config MODULE_COMPRESS_NONE
-	bool "None"
+choice
+	prompt "Module compression type"
+	depends on MODULE_COMPRESS
 	help
-	  Do not compress modules. The installed modules are suffixed
-	  with .ko.
+	  Choose the supported algorithm for module compression.
 
 config MODULE_COMPRESS_GZIP
 	bool "GZIP"
 	help
-	  Compress modules with GZIP. The installed modules are suffixed
-	  with .ko.gz.
+	  Support modules compressed with GZIP. The installed modules are
+	  suffixed with .ko.gz.
 
 config MODULE_COMPRESS_XZ
 	bool "XZ"
 	help
-	  Compress modules with XZ. The installed modules are suffixed
-	  with .ko.xz.
+	  Support modules compressed with XZ. The installed modules are
+	  suffixed with .ko.xz.
 
 config MODULE_COMPRESS_ZSTD
 	bool "ZSTD"
 	help
-	  Compress modules with ZSTD. The installed modules are suffixed
-	  with .ko.zst.
+	  Support modules compressed with ZSTD. The installed modules are
+	  suffixed with .ko.zst.
 
 endchoice
 
+config MODULE_COMPRESS_ALL
+	bool "Automatically compress all modules"
+	default y
+	depends on MODULE_COMPRESS
+	help
+	  Compress all modules during 'make modules_install'.
+
+	  Your build system needs to provide the appropriate compression tool
+	  for the selected compression type. External modules will also be
+	  compressed in the same way during the installation.
+
 config MODULE_DECOMPRESS
 	bool "Support in-kernel module decompression"
-	depends on MODULE_COMPRESS_GZIP || MODULE_COMPRESS_XZ || MODULE_COMPRESS_ZSTD
+	depends on MODULE_COMPRESS
 	select ZLIB_INFLATE if MODULE_COMPRESS_GZIP
 	select XZ_DEC if MODULE_COMPRESS_XZ
 	select ZSTD_DECOMPRESS if MODULE_COMPRESS_ZSTD
 	help
-
 	  Support for decompressing kernel modules by the kernel itself
 	  instead of relying on userspace to perform this task. Useful when
 	  load pinning security policy is enabled.
diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst
index 0afd75472679..bce4a9adb893 100644
--- a/scripts/Makefile.modinst
+++ b/scripts/Makefile.modinst
@@ -51,9 +51,11 @@ $(foreach x, % :, $(if $(findstring $x, $(dst)), \
 	$(error module installation path cannot contain '$x')))
 
 suffix-y				:=
+ifdef CONFIG_MODULE_COMPRESS_ALL
 suffix-$(CONFIG_MODULE_COMPRESS_GZIP)	:= .gz
 suffix-$(CONFIG_MODULE_COMPRESS_XZ)	:= .xz
 suffix-$(CONFIG_MODULE_COMPRESS_ZSTD)	:= .zst
+endif
 
 modules := $(patsubst $(extmod_prefix)%.o, $(dst)/%.ko$(suffix-y), $(modules))
 install-$(CONFIG_MODULES) += $(modules)
-- 
2.35.3

Re: [PATCH 1/2] module: Split modules_install compression and in-kernel decompression

[Masahiro Yamada]

On Mon, Jul 22, 2024 at 6:07 PM Petr Pavlu <petr.pavlu@suse.com> wrote:
>
> The kernel configuration allows specifying a module compression mode. If
> one is selected then each module gets compressed during
> 'make modules_install' and additionally one can also enable support for
> a respective direct in-kernel decompression support. This means that the
> decompression support cannot be enabled without the automatic compression.
>
> Some distributions, such as the (open)SUSE family, use a signer service for
> modules. A build runs on a worker machine but signing is done by a separate
> locked-down server that is in possession of the signing key. The build
> invokes 'make modules_install' to create a modules tree, collects
> information about the modules, asks the signer service for their signature,
> appends each signature to the respective module and compresses all modules.
>
> When using this arrangment, the 'make modules_install' step produces
> unsigned+uncompressed modules and the distribution's own build recipe takes
> care of signing and compression later.
>
> The signing support can be currently enabled without automatically signing
> modules during 'make modules_install'. However, the in-kernel decompression
> support can be selected only after first enabling automatic compression
> during this step.
>
> To allow only enabling the in-kernel decompression support without the
> automatic compression during 'make modules_install', separate the
> compression options similarly to the signing options, as follows:
>
> > Enable loadable module support
> [*] Module compression
>       Module compression type (GZIP)  --->
> [*]   Automatically compress all modules
> [ ]   Support in-kernel module decompression
>
> * "Module compression" (MODULE_COMPRESS) is a new main switch for the
>   compression/decompression support. It replaces MODULE_COMPRESS_NONE.
> * "Module compression type" (MODULE_COMPRESS_<type>) chooses the
>   compression type, one of GZ, XZ, ZSTD.
> * "Automatically compress all modules" (MODULE_COMPRESS_ALL) is a new
>   option to enable module compression during 'make modules_install'. It
>   defaults to Y.
> * "Support in-kernel module decompression" (MODULE_DECOMPRESS) enables
>   in-kernel decompression.
>
> Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
> ---



My preference is to add
 CONFIG_MODULE_DECOMPRESS_GZIP
 CONFIG_MODULE_DECOMPRESS_XZ
 CONFIG_MODULE_DECOMPRESS_ZSTD
instead of
 CONFIG_MODULE_COMPRESS_ALL.




For example,


if MODULE_DECOMPRESS

config MODULE_DECOMPRESS_GZIP
       bool "Support in-kernel GZIP decompression for module"
       default MODULE_COMPRESS_GZIP

config MODULE_DECOMPRESS_XZ
       bool "Support in-kernel XZ decompression for module"
       default MODULE_COMPRESS_XZ

config MODULE_DECOMPRESS_ZSTD
       bool "Support in-kernel ZSTD decompression for module"
       default MODULE_COMPRESS_ZSTD

endif





OR, maybe



config MODULE_DECOMPRESS_GZIP
       bool "Support in-kernel GZIP decompression for module"
       select MODULE_DECOMPRESS

config MODULE_DECOMPRESS_XZ
       bool "Support in-kernel XZ decompression for module"
       select MODULE_DECOMPRESS

config MODULE_DECOMPRESS_ZSTD
       bool "Support in-kernel ZSTD decompression for module"
       select MODULE_DECOMPRESS

config MODULE_DECOMPRESS
       bool




You can toggle MODULE_COMPRESS_GZIP and
MODULE_DECOMPRESS_GZIP independently


Of course, the current kernel/module/decompress.c does not
work when multiple (or zero) CONFIG_MODULE_DECOMPRESS_* is
enabled. It needs a little modification.


I will wait for Lius's comment.







>  kernel/module/Kconfig    | 61 ++++++++++++++++++++--------------------
>  scripts/Makefile.modinst |  2 ++
>  2 files changed, 33 insertions(+), 30 deletions(-)
>
> diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
> index 4047b6d48255..bb7f7930fef6 100644
> --- a/kernel/module/Kconfig
> +++ b/kernel/module/Kconfig
> @@ -278,64 +278,65 @@ config MODULE_SIG_HASH
>         default "sha3-384" if MODULE_SIG_SHA3_384
>         default "sha3-512" if MODULE_SIG_SHA3_512
>
> -choice
> -       prompt "Module compression mode"
> +config MODULE_COMPRESS
> +       bool "Module compression"
>         help
> -         This option allows you to choose the algorithm which will be used to
> -         compress modules when 'make modules_install' is run. (or, you can
> -         choose to not compress modules at all.)
> -
> -         External modules will also be compressed in the same way during the
> -         installation.
> -
> -         For modules inside an initrd or initramfs, it's more efficient to
> -         compress the whole initrd or initramfs instead.
> -
> +         Enable module compression to reduce on-disk size of module binaries.
>           This is fully compatible with signed modules.
>
> -         Please note that the tool used to load modules needs to support the
> -         corresponding algorithm. module-init-tools MAY support gzip, and kmod
> -         MAY support gzip, xz and zstd.
> +         The tool used to work with modules needs to support the selected
> +         compression type. kmod MAY support gzip, xz and zstd. Other tools
> +         might have a limited selection of the supported types.
>
> -         Your build system needs to provide the appropriate compression tool
> -         to compress the modules.
> +         Note that for modules inside an initrd or initramfs, it's more
> +         efficient to compress the whole ramdisk instead.
>
> -         If in doubt, select 'None'.
> +         If unsure, say N.
>
> -config MODULE_COMPRESS_NONE
> -       bool "None"
> +choice
> +       prompt "Module compression type"
> +       depends on MODULE_COMPRESS
>         help
> -         Do not compress modules. The installed modules are suffixed
> -         with .ko.
> +         Choose the supported algorithm for module compression.
>
>  config MODULE_COMPRESS_GZIP
>         bool "GZIP"
>         help
> -         Compress modules with GZIP. The installed modules are suffixed
> -         with .ko.gz.
> +         Support modules compressed with GZIP. The installed modules are
> +         suffixed with .ko.gz.
>
>  config MODULE_COMPRESS_XZ
>         bool "XZ"
>         help
> -         Compress modules with XZ. The installed modules are suffixed
> -         with .ko.xz.
> +         Support modules compressed with XZ. The installed modules are
> +         suffixed with .ko.xz.
>
>  config MODULE_COMPRESS_ZSTD
>         bool "ZSTD"
>         help
> -         Compress modules with ZSTD. The installed modules are suffixed
> -         with .ko.zst.
> +         Support modules compressed with ZSTD. The installed modules are
> +         suffixed with .ko.zst.
>
>  endchoice
>
> +config MODULE_COMPRESS_ALL
> +       bool "Automatically compress all modules"
> +       default y
> +       depends on MODULE_COMPRESS
> +       help
> +         Compress all modules during 'make modules_install'.
> +
> +         Your build system needs to provide the appropriate compression tool
> +         for the selected compression type. External modules will also be
> +         compressed in the same way during the installation.
> +
>  config MODULE_DECOMPRESS
>         bool "Support in-kernel module decompression"
> -       depends on MODULE_COMPRESS_GZIP || MODULE_COMPRESS_XZ || MODULE_COMPRESS_ZSTD
> +       depends on MODULE_COMPRESS
>         select ZLIB_INFLATE if MODULE_COMPRESS_GZIP
>         select XZ_DEC if MODULE_COMPRESS_XZ
>         select ZSTD_DECOMPRESS if MODULE_COMPRESS_ZSTD
>         help
> -
>           Support for decompressing kernel modules by the kernel itself
>           instead of relying on userspace to perform this task. Useful when
>           load pinning security policy is enabled.
> diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst
> index 0afd75472679..bce4a9adb893 100644
> --- a/scripts/Makefile.modinst
> +++ b/scripts/Makefile.modinst
> @@ -51,9 +51,11 @@ $(foreach x, % :, $(if $(findstring $x, $(dst)), \
>         $(error module installation path cannot contain '$x')))
>
>  suffix-y                               :=
> +ifdef CONFIG_MODULE_COMPRESS_ALL
>  suffix-$(CONFIG_MODULE_COMPRESS_GZIP)  := .gz
>  suffix-$(CONFIG_MODULE_COMPRESS_XZ)    := .xz
>  suffix-$(CONFIG_MODULE_COMPRESS_ZSTD)  := .zst
> +endif
>
>  modules := $(patsubst $(extmod_prefix)%.o, $(dst)/%.ko$(suffix-y), $(modules))
>  install-$(CONFIG_MODULES) += $(modules)
> --
> 2.35.3
>


-- 
Best Regards
Masahiro Yamada

Re: [PATCH 1/2] module: Split modules_install compression and in-kernel decompression

[Petr Pavlu]

On 7/22/24 12:23, Masahiro Yamada wrote:
> On Mon, Jul 22, 2024 at 6:07 PM Petr Pavlu <petr.pavlu@suse.com> wrote:
>>
>> The kernel configuration allows specifying a module compression mode. If
>> one is selected then each module gets compressed during
>> 'make modules_install' and additionally one can also enable support for
>> a respective direct in-kernel decompression support. This means that the
>> decompression support cannot be enabled without the automatic compression.
>>
>> Some distributions, such as the (open)SUSE family, use a signer service for
>> modules. A build runs on a worker machine but signing is done by a separate
>> locked-down server that is in possession of the signing key. The build
>> invokes 'make modules_install' to create a modules tree, collects
>> information about the modules, asks the signer service for their signature,
>> appends each signature to the respective module and compresses all modules.
>>
>> When using this arrangment, the 'make modules_install' step produces
>> unsigned+uncompressed modules and the distribution's own build recipe takes
>> care of signing and compression later.
>>
>> The signing support can be currently enabled without automatically signing
>> modules during 'make modules_install'. However, the in-kernel decompression
>> support can be selected only after first enabling automatic compression
>> during this step.
>>
>> To allow only enabling the in-kernel decompression support without the
>> automatic compression during 'make modules_install', separate the
>> compression options similarly to the signing options, as follows:
>>
>>> Enable loadable module support
>> [*] Module compression
>>       Module compression type (GZIP)  --->
>> [*]   Automatically compress all modules
>> [ ]   Support in-kernel module decompression
>>
>> * "Module compression" (MODULE_COMPRESS) is a new main switch for the
>>   compression/decompression support. It replaces MODULE_COMPRESS_NONE.
>> * "Module compression type" (MODULE_COMPRESS_<type>) chooses the
>>   compression type, one of GZ, XZ, ZSTD.
>> * "Automatically compress all modules" (MODULE_COMPRESS_ALL) is a new
>>   option to enable module compression during 'make modules_install'. It
>>   defaults to Y.
>> * "Support in-kernel module decompression" (MODULE_DECOMPRESS) enables
>>   in-kernel decompression.
>>
>> Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
>> ---
> 
> 
> 
> My preference is to add
>  CONFIG_MODULE_DECOMPRESS_GZIP
>  CONFIG_MODULE_DECOMPRESS_XZ
>  CONFIG_MODULE_DECOMPRESS_ZSTD
> instead of
>  CONFIG_MODULE_COMPRESS_ALL.
> 
> 
> 
> 
> For example,
> 
> 
> if MODULE_DECOMPRESS
> 
> config MODULE_DECOMPRESS_GZIP
>        bool "Support in-kernel GZIP decompression for module"
>        default MODULE_COMPRESS_GZIP
> 
> config MODULE_DECOMPRESS_XZ
>        bool "Support in-kernel XZ decompression for module"
>        default MODULE_COMPRESS_XZ
> 
> config MODULE_DECOMPRESS_ZSTD
>        bool "Support in-kernel ZSTD decompression for module"
>        default MODULE_COMPRESS_ZSTD
> 
> endif
> 
> 
> 
> 
> 
> OR, maybe
> 
> 
> 
> config MODULE_DECOMPRESS_GZIP
>        bool "Support in-kernel GZIP decompression for module"
>        select MODULE_DECOMPRESS
> 
> config MODULE_DECOMPRESS_XZ
>        bool "Support in-kernel XZ decompression for module"
>        select MODULE_DECOMPRESS
> 
> config MODULE_DECOMPRESS_ZSTD
>        bool "Support in-kernel ZSTD decompression for module"
>        select MODULE_DECOMPRESS
> 
> config MODULE_DECOMPRESS
>        bool
> 
> 
> 
> 
> You can toggle MODULE_COMPRESS_GZIP and
> MODULE_DECOMPRESS_GZIP independently

I can implement this, but what would be a use case to enable multiple module
decompression types in the kernel?

> 
> 
> Of course, the current kernel/module/decompress.c does not
> work when multiple (or zero) CONFIG_MODULE_DECOMPRESS_* is
> enabled. It needs a little modification.

One issue is with the file /sys/module/compression which shows the module
decompression type supported by the kernel. If multiple types are allowed then
I think they should all get listed there. This could however create some
compatibility problems. For instance, kmod reads this file and currently
expects to find exactly one type, so it would need updating as well.

Thanks,
Petr

Re: [PATCH 1/2] module: Split modules_install compression and in-kernel decompression

[Masahiro Yamada]

On Thu, Jul 25, 2024 at 9:59 PM Petr Pavlu <petr.pavlu@suse.com> wrote:
>
> On 7/22/24 12:23, Masahiro Yamada wrote:
> > On Mon, Jul 22, 2024 at 6:07 PM Petr Pavlu <petr.pavlu@suse.com> wrote:
> >>
> >> The kernel configuration allows specifying a module compression mode. If
> >> one is selected then each module gets compressed during
> >> 'make modules_install' and additionally one can also enable support for
> >> a respective direct in-kernel decompression support. This means that the
> >> decompression support cannot be enabled without the automatic compression.
> >>
> >> Some distributions, such as the (open)SUSE family, use a signer service for
> >> modules. A build runs on a worker machine but signing is done by a separate
> >> locked-down server that is in possession of the signing key. The build
> >> invokes 'make modules_install' to create a modules tree, collects
> >> information about the modules, asks the signer service for their signature,
> >> appends each signature to the respective module and compresses all modules.
> >>
> >> When using this arrangment, the 'make modules_install' step produces
> >> unsigned+uncompressed modules and the distribution's own build recipe takes
> >> care of signing and compression later.
> >>
> >> The signing support can be currently enabled without automatically signing
> >> modules during 'make modules_install'. However, the in-kernel decompression
> >> support can be selected only after first enabling automatic compression
> >> during this step.
> >>
> >> To allow only enabling the in-kernel decompression support without the
> >> automatic compression during 'make modules_install', separate the
> >> compression options similarly to the signing options, as follows:
> >>
> >>> Enable loadable module support
> >> [*] Module compression
> >>       Module compression type (GZIP)  --->
> >> [*]   Automatically compress all modules
> >> [ ]   Support in-kernel module decompression
> >>
> >> * "Module compression" (MODULE_COMPRESS) is a new main switch for the
> >>   compression/decompression support. It replaces MODULE_COMPRESS_NONE.
> >> * "Module compression type" (MODULE_COMPRESS_<type>) chooses the
> >>   compression type, one of GZ, XZ, ZSTD.
> >> * "Automatically compress all modules" (MODULE_COMPRESS_ALL) is a new
> >>   option to enable module compression during 'make modules_install'. It
> >>   defaults to Y.
> >> * "Support in-kernel module decompression" (MODULE_DECOMPRESS) enables
> >>   in-kernel decompression.
> >>
> >> Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
> >> ---
> >
> >
> >
> > My preference is to add
> >  CONFIG_MODULE_DECOMPRESS_GZIP
> >  CONFIG_MODULE_DECOMPRESS_XZ
> >  CONFIG_MODULE_DECOMPRESS_ZSTD
> > instead of
> >  CONFIG_MODULE_COMPRESS_ALL.
> >
> >
> >
> >
> > For example,
> >
> >
> > if MODULE_DECOMPRESS
> >
> > config MODULE_DECOMPRESS_GZIP
> >        bool "Support in-kernel GZIP decompression for module"
> >        default MODULE_COMPRESS_GZIP
> >
> > config MODULE_DECOMPRESS_XZ
> >        bool "Support in-kernel XZ decompression for module"
> >        default MODULE_COMPRESS_XZ
> >
> > config MODULE_DECOMPRESS_ZSTD
> >        bool "Support in-kernel ZSTD decompression for module"
> >        default MODULE_COMPRESS_ZSTD
> >
> > endif
> >
> >
> >
> >
> >
> > OR, maybe
> >
> >
> >
> > config MODULE_DECOMPRESS_GZIP
> >        bool "Support in-kernel GZIP decompression for module"
> >        select MODULE_DECOMPRESS
> >
> > config MODULE_DECOMPRESS_XZ
> >        bool "Support in-kernel XZ decompression for module"
> >        select MODULE_DECOMPRESS
> >
> > config MODULE_DECOMPRESS_ZSTD
> >        bool "Support in-kernel ZSTD decompression for module"
> >        select MODULE_DECOMPRESS
> >
> > config MODULE_DECOMPRESS
> >        bool
> >
> >
> >
> >
> > You can toggle MODULE_COMPRESS_GZIP and
> > MODULE_DECOMPRESS_GZIP independently
>
> I can implement this, but what would be a use case to enable multiple module
> decompression types in the kernel?


I just thought there is a possibility where the singer service A
compresses modules in GZIP, and the singer service B in XZ, etc.

If the compression type is predictable at the Kbuild time,
it is fine.




>
> >
> >
> > Of course, the current kernel/module/decompress.c does not
> > work when multiple (or zero) CONFIG_MODULE_DECOMPRESS_* is
> > enabled. It needs a little modification.
>
> One issue is with the file /sys/module/compression which shows the module
> decompression type supported by the kernel. If multiple types are allowed then
> I think they should all get listed there. This could however create some
> compatibility problems. For instance, kmod reads this file and currently
> expects to find exactly one type, so it would need updating as well.


OK, understood. Then,

Acked-by: Masahiro Yamada <masahiroy@kernel.org>



--
Best Regards
Masahiro Yamada

[PATCH 2/2] module: Clean up the description of MODULE_SIG_<type>

[Petr Pavlu]

The MODULE_SIG_<type> config choice has an inconsistent prompt styled as
a question and lengthy option names.

Simplify the prompt and option names to be consistent with other module
options.

Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>
---
 kernel/module/Kconfig | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
index bb7f7930fef6..ccdbd1bc12aa 100644
--- a/kernel/module/Kconfig
+++ b/kernel/module/Kconfig
@@ -228,7 +228,7 @@ comment "Do not forget to sign required modules with scripts/sign-file"
 	depends on MODULE_SIG_FORCE && !MODULE_SIG_ALL
 
 choice
-	prompt "Which hash algorithm should modules be signed with?"
+	prompt "Hash algorithm to sign modules"
 	depends on MODULE_SIG || IMA_APPRAISE_MODSIG
 	help
 	  This determines which sort of hashing algorithm will be used during
@@ -238,31 +238,31 @@ choice
 	  the signature on that module.
 
 config MODULE_SIG_SHA1
-	bool "Sign modules with SHA-1"
+	bool "SHA-1"
 	select CRYPTO_SHA1
 
 config MODULE_SIG_SHA256
-	bool "Sign modules with SHA-256"
+	bool "SHA-256"
 	select CRYPTO_SHA256
 
 config MODULE_SIG_SHA384
-	bool "Sign modules with SHA-384"
+	bool "SHA-384"
 	select CRYPTO_SHA512
 
 config MODULE_SIG_SHA512
-	bool "Sign modules with SHA-512"
+	bool "SHA-512"
 	select CRYPTO_SHA512
 
 config MODULE_SIG_SHA3_256
-	bool "Sign modules with SHA3-256"
+	bool "SHA3-256"
 	select CRYPTO_SHA3
 
 config MODULE_SIG_SHA3_384
-	bool "Sign modules with SHA3-384"
+	bool "SHA3-384"
 	select CRYPTO_SHA3
 
 config MODULE_SIG_SHA3_512
-	bool "Sign modules with SHA3-512"
+	bool "SHA3-512"
 	select CRYPTO_SHA3
 
 endchoice
-- 
2.35.3

Re: [PATCH 0/2] module: Split modules_install compression and in-kernel decompression

[Luis Chamberlain]

On Mon, Jul 22, 2024 at 11:06:20AM +0200, Petr Pavlu wrote:
> Allow enabling the in-kernel module decompression support separately,
> without requiring to enable also the automatic compression during
> 'make modules_install'.

Applied and pushed, thanks!

  Luis