| Message ID | 20230914112739.112729-1-alessandro.carminati@gmail.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Enhancing Boot Speed and Security with Delayed Module Signature Verification | expand |
On 9/14/23 07:27, Alessandro Carminati (Red Hat) wrote: > This patch sets up a new feature to the Linux kernel to have the ability, > while module signature checking is enabled, to delay the moment where > these signatures are effectively checked. The feature is structure into > two main key points, the feature can be enabled by a new command line > kernel argument, while in delay mode, the kernel waits until the > userspace communicates to start checking signature modules. > This operation can be done by writing a value in a securityfs file, > which works the same as /sys/kernel/security/lockdown. > > Patch 1/2: Modules: Introduce boot-time module signature flexibility > The first patch in this set fundamentally alters the kernel's behavior > at boot time by implementing a delayed module signature verification > mechanism. It introduces a new boot-time kernel argument that allows > users to request this delay. By doing so, we aim to capitalize on the > cryptographic checks already performed on the kernel and initrd images > during the secure boot process. As a result, we can significantly > improve the boot speed without compromising system security. > > Patch 2/2: docs: Update kernel-parameters.txt for signature verification > enhancement > The second patch is just to update the kernel parameters list > documentation. > > Background and Motivation > In certain contexts, boot speed becomes crucial. This patch follows the > recognition that security checks can at times be redundant. Therefore, > it proves valuable to skip those checks that have already been validated. > > In a typical Secure Boot startup with an initrd, the bootloader is > responsible for verifying artifacts before relinquishing control. In a > verified initrd image, it is reasonable to assume that its content is > also secure. Consequently, verifying module signatures may be deemed > unnecessary. > This patch introduces a feature to skip signature verification during > the initrd boot phase. > I think this is fine to do. There is some risk for users who may use this without realizing what they're actually doing and then would end up creating a security hole. But there are far worse ways you can do that with access to kernel paramaters. P. > Alessandro Carminati (Red Hat) (2): > Modules: Introduce boot-time module signature flexibility > docs: Update kernel-parameters.txt for signature verification > enhancement > > .../admin-guide/kernel-parameters.txt | 9 +++ > include/linux/module.h | 4 ++ > kernel/module/main.c | 14 +++-- > kernel/module/signing.c | 56 +++++++++++++++++++ > 4 files changed, 77 insertions(+), 6 deletions(-) >
gentle ping Il giorno gio 14 set 2023 alle ore 13:28 Alessandro Carminati (Red Hat) <alessandro.carminati@gmail.com> ha scritto: > > This patch sets up a new feature to the Linux kernel to have the ability, > while module signature checking is enabled, to delay the moment where > these signatures are effectively checked. The feature is structure into > two main key points, the feature can be enabled by a new command line > kernel argument, while in delay mode, the kernel waits until the > userspace communicates to start checking signature modules. > This operation can be done by writing a value in a securityfs file, > which works the same as /sys/kernel/security/lockdown. > > Patch 1/2: Modules: Introduce boot-time module signature flexibility > The first patch in this set fundamentally alters the kernel's behavior > at boot time by implementing a delayed module signature verification > mechanism. It introduces a new boot-time kernel argument that allows > users to request this delay. By doing so, we aim to capitalize on the > cryptographic checks already performed on the kernel and initrd images > during the secure boot process. As a result, we can significantly > improve the boot speed without compromising system security. > > Patch 2/2: docs: Update kernel-parameters.txt for signature verification > enhancement > The second patch is just to update the kernel parameters list > documentation. > > Background and Motivation > In certain contexts, boot speed becomes crucial. This patch follows the > recognition that security checks can at times be redundant. Therefore, > it proves valuable to skip those checks that have already been validated. > > In a typical Secure Boot startup with an initrd, the bootloader is > responsible for verifying artifacts before relinquishing control. In a > verified initrd image, it is reasonable to assume that its content is > also secure. Consequently, verifying module signatures may be deemed > unnecessary. > This patch introduces a feature to skip signature verification during > the initrd boot phase. > > Alessandro Carminati (Red Hat) (2): > Modules: Introduce boot-time module signature flexibility > docs: Update kernel-parameters.txt for signature verification > enhancement > > .../admin-guide/kernel-parameters.txt | 9 +++ > include/linux/module.h | 4 ++ > kernel/module/main.c | 14 +++-- > kernel/module/signing.c | 56 +++++++++++++++++++ > 4 files changed, 77 insertions(+), 6 deletions(-) > > -- > 2.34.1 >
This patch sets up a new feature to the Linux kernel to have the ability, while module signature checking is enabled, to delay the moment where these signatures are effectively checked. The feature is structure into two main key points, the feature can be enabled by a new command line kernel argument, while in delay mode, the kernel waits until the userspace communicates to start checking signature modules. This operation can be done by writing a value in a securityfs file, which works the same as /sys/kernel/security/lockdown. Patch 1/2: Modules: Introduce boot-time module signature flexibility The first patch in this set fundamentally alters the kernel's behavior at boot time by implementing a delayed module signature verification mechanism. It introduces a new boot-time kernel argument that allows users to request this delay. By doing so, we aim to capitalize on the cryptographic checks already performed on the kernel and initrd images during the secure boot process. As a result, we can significantly improve the boot speed without compromising system security. Patch 2/2: docs: Update kernel-parameters.txt for signature verification enhancement The second patch is just to update the kernel parameters list documentation. Background and Motivation In certain contexts, boot speed becomes crucial. This patch follows the recognition that security checks can at times be redundant. Therefore, it proves valuable to skip those checks that have already been validated. In a typical Secure Boot startup with an initrd, the bootloader is responsible for verifying artifacts before relinquishing control. In a verified initrd image, it is reasonable to assume that its content is also secure. Consequently, verifying module signatures may be deemed unnecessary. This patch introduces a feature to skip signature verification during the initrd boot phase. Alessandro Carminati (Red Hat) (2): Modules: Introduce boot-time module signature flexibility docs: Update kernel-parameters.txt for signature verification enhancement .../admin-guide/kernel-parameters.txt | 9 +++ include/linux/module.h | 4 ++ kernel/module/main.c | 14 +++-- kernel/module/signing.c | 56 +++++++++++++++++++ 4 files changed, 77 insertions(+), 6 deletions(-)