| Message ID | 20181005174015.21939-1-nayna@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Add support for architecture specific IMA policies | expand |
On Fri, 2018-10-05 at 23:10 +0530, Nayna Jain wrote: > From: Nayna Jain <nayna@linux.ibm.com> > > The architecture specific policy, introduced in this patch set, permits > different architectures to define IMA policy rules based on kernel > configuration and system runtime information. > > For example, on x86, there are two methods of verifying the kexec'ed kernel > image signature - CONFIG_KEXEC_VERIFY_SIG and IMA appraisal policy > KEXEC_KERNEL_CHECK. CONFIG_KEXEC_VERIFY_SIG enforces the kexec_file_load > syscall to verify file signatures, but does not prevent the kexec_load > syscall. The IMA KEXEC_KERNEL_CHECK policy rule verifies the kexec'ed > kernel image, loaded via the kexec_file_load syscall, is validly signed and > prevents loading a kernel image via the kexec_load syscall. When secure > boot is enabled, the kexec'ed kernel image needs to be signed and the > signature verified. In this environment, either method of verifying the > kexec'ed kernel image is acceptable, as long as the kexec_load syscall is > disabled. > > The previous version of this patchset introduced a new IMA policy rule to > disable the kexec_load syscall, when CONFIG_KEXEC_VERIFY_SIG was enabled, > however that is removed from this version by introducing a different > mechanism, as described below. > > The patchset defines an arch_ima_get_secureboot() function to retrieve the > secureboot state of the system. If secureboot is enabled and > CONFIG_KEXEC_VERIFY_SIG is configured, it denies permission to kexec_load > syscall. > > To support architecture specific policies, a new function > arch_get_ima_policy() is defined. This patch set defines IMA > KERNEL_KEXEC_POLICY rules for x86 *only* if CONFIG_KEXEC_VERIFY_SIG is > disabled and secure boot is enabled. > > This patch set includes a patch, which refactors ima_init_policy() to > remove code duplication. Other than a couple of #ifdef's in .c files, which should be converted to use IS_ENABLED(<config-option>), the patch set is looking really good. thanks! Mimi
From: Nayna Jain <nayna@linux.ibm.com> The architecture specific policy, introduced in this patch set, permits different architectures to define IMA policy rules based on kernel configuration and system runtime information. For example, on x86, there are two methods of verifying the kexec'ed kernel image signature - CONFIG_KEXEC_VERIFY_SIG and IMA appraisal policy KEXEC_KERNEL_CHECK. CONFIG_KEXEC_VERIFY_SIG enforces the kexec_file_load syscall to verify file signatures, but does not prevent the kexec_load syscall. The IMA KEXEC_KERNEL_CHECK policy rule verifies the kexec'ed kernel image, loaded via the kexec_file_load syscall, is validly signed and prevents loading a kernel image via the kexec_load syscall. When secure boot is enabled, the kexec'ed kernel image needs to be signed and the signature verified. In this environment, either method of verifying the kexec'ed kernel image is acceptable, as long as the kexec_load syscall is disabled. The previous version of this patchset introduced a new IMA policy rule to disable the kexec_load syscall, when CONFIG_KEXEC_VERIFY_SIG was enabled, however that is removed from this version by introducing a different mechanism, as described below. The patchset defines an arch_ima_get_secureboot() function to retrieve the secureboot state of the system. If secureboot is enabled and CONFIG_KEXEC_VERIFY_SIG is configured, it denies permission to kexec_load syscall. To support architecture specific policies, a new function arch_get_ima_policy() is defined. This patch set defines IMA KERNEL_KEXEC_POLICY rules for x86 *only* if CONFIG_KEXEC_VERIFY_SIG is disabled and secure boot is enabled. This patch set includes a patch, which refactors ima_init_policy() to remove code duplication. Changelog: v5: * ima: refactor ima_init_policy() - Includes Mimi's feedback - updated patch description, and code fixes. * ima: add support for arch specific policies - Includes Mimi's feedback - updated comment. * ima: add support for external setting of ima_appraise - Includes Mimi's feedback - This patch is deleted. This is handled by enabling IMA_APPRAISE_BOOTPARAM only if IMA_ARCH_POLICY is not enabled. The change is done in the Patch 5/5. v4: * ima: refactor ima_init_policy() - Fixed the issue reported by Dan Carpenter. Replaced logical operator (&&) with bitwise operator (&). v3: * x86/ima: define arch_ima_get_secureboot - Edited subject line, added x86. * x86/ima: define arch_get_ima_policy() for x86 - Fixed the error reported by kbuild test robot. The error was appearing when CONFIG_X86 is enabled, but CONFIG_IMA_ARCH_POLICY is disabled. v2: * ima: define arch_ima_get_secureboot - New Patch - to retrieve secureboot state of the system * ima: prevent kexec_load syscall based on runtime secureboot flag - New Patch - disables kexec_load if KEXEC_VERIFY_SIG is configured and secureboot is enabled * ima: refactor ima_init_policy() - New Patch - cleans up the code duplication in ima_init_policy(), adds new function add_rules() * ima: add support for arch specific policies - modified ima_init_arch_policy() and ima_init_policy() to use add_rules() from previous patch. * ima: add support for external setting of ima_appraise - sets ima_appraise flag explicitly for arch_specific setting * ima: add support for KEXEC_ORIG_KERNEL_CHECK - deleted the patch based on Seth's feedback * x86/ima: define arch_get_ima_policy() for x86 - removes the policy KEXEC_ORIG_KERNEL_CHECK based on Seth's feedback. Eric Richter (1): x86/ima: define arch_get_ima_policy() for x86 Nayna Jain (4): x86/ima: define arch_ima_get_secureboot ima: prevent kexec_load syscall based on runtime secureboot flag ima: refactor ima_init_policy() ima: add support for arch specific policies arch/x86/kernel/Makefile | 2 + arch/x86/kernel/ima_arch.c | 35 ++++++++ include/linux/ima.h | 18 ++++ security/integrity/ima/Kconfig | 10 ++- security/integrity/ima/ima_main.c | 17 ++-- security/integrity/ima/ima_policy.c | 166 +++++++++++++++++++++++++++--------- 6 files changed, 199 insertions(+), 49 deletions(-) create mode 100644 arch/x86/kernel/ima_arch.c