EVM and other LSMs need the ability to query the secure boot status of
the system, without directly calling the IMA arch_ima_get_secureboot
function. Refactor the secure boot status check into a general function
named arch_get_secureboot.
Reported-and-suggested-by: Mimi Zohar <zohar@linux.ibm.com>
Suggested-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Coiby Xu <coxu@redhat.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Commit 273df864cf ("ima: Check against blacklisted hashes for files with
modsig") introduced an appraise_flag option for referencing the blacklist
keyring. Any matching binary found on this keyring fails signature
validation. This flag only works with module appended signatures.
An important part of a PKI infrastructure is to have the ability to do
revocation at a later time should a vulnerability be found. Expand the
revocation flag usage to all appraisal functions. The flag is now
enabled by default. Setting the flag with an IMA policy has been
deprecated. Without a revocation capability like this in place, only
authenticity can be maintained. With this change, integrity can now be
achieved with digital signature based IMA appraisal.
Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Reviewed-by: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
To prevent verifying the kernel module appended signature
twice (finit_module), once by the module_sig_check() and again by IMA,
powerpc secure boot rules define an IMA architecture specific policy
rule only if CONFIG_MODULE_SIG_FORCE is not enabled. This,
unfortunately, does not take into account the ability of enabling
"sig_enforce" on the boot command line (module.sig_enforce=1).
Including the IMA module appraise rule results in failing the
finit_module syscall, unless the module signing public key is loaded
onto the IMA keyring.
This patch fixes secure boot policy rules to be based on
CONFIG_MODULE_SIG instead.
Fixes: 4238fad366 ("powerpc/ima: Add support to initialize ima policy rules")
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Link: https://lore.kernel.org/r/1588342612-14532-1-git-send-email-nayna@linux.ibm.com
The arch specific kernel module policy rule requires kernel modules to
be signed, either as an IMA signature, stored as an xattr, or as an
appended signature. As a result, kernel modules appended signatures
could be enforced without "sig_enforce" being set or reflected in
/sys/module/module/parameters/sig_enforce. This patch sets
"sig_enforce".
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1572492694-6520-10-git-send-email-zohar@linux.ibm.com
PowerNV systems use a Linux-based bootloader, which rely on the IMA
subsystem to enforce different secure boot modes. Since the
verification policy may differ based on the secure boot mode of the
system, the policies must be defined at runtime.
This patch implements arch-specific support to define IMA policy rules
based on the runtime secure boot mode of the system.
This patch provides arch-specific IMA policies if PPC_SECURE_BOOT
config is enabled.
Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1572492694-6520-3-git-send-email-zohar@linux.ibm.com
