| Message ID | 20181208202705.18673-8-nayna@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | add platform/firmware keys support for kernel verification by IMA | expand |
On Sun, 9 Dec 2018, Nayna Jain wrote: > On secure boot enabled systems, the bootloader verifies the kernel > image and possibly the initramfs signatures based on a set of keys. A > soft reboot(kexec) of the system, with the same kernel image and > initramfs, requires access to the original keys to verify the > signatures. > > This patch allows IMA-appraisal access to those original keys, now > loaded on the platform keyring, needed for verifying the kernel image > and initramfs signatures. > > Signed-off-by: Nayna Jain <nayna@linux.ibm.com> > Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> > Acked-by: Serge Hallyn <serge@hallyn.com> > - replace 'rc' with 'xattr_len' when calling integrity_digsig_verify() > with INTEGRITY_KEYRING_IMA for readability > Suggested-by: Serge Hallyn <serge@hallyn.com> Reviewed-by: James Morris <james.morris@microsoft.com>
Hello, Nayna Jain <nayna@linux.ibm.com> writes: > On secure boot enabled systems, the bootloader verifies the kernel > image and possibly the initramfs signatures based on a set of keys. A > soft reboot(kexec) of the system, with the same kernel image and > initramfs, requires access to the original keys to verify the > signatures. > > This patch allows IMA-appraisal access to those original keys, now > loaded on the platform keyring, needed for verifying the kernel image > and initramfs signatures. > > Signed-off-by: Nayna Jain <nayna@linux.ibm.com> > Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> > Acked-by: Serge Hallyn <serge@hallyn.com> > - replace 'rc' with 'xattr_len' when calling integrity_digsig_verify() > with INTEGRITY_KEYRING_IMA for readability > Suggested-by: Serge Hallyn <serge@hallyn.com> > --- > Changelog: > > v2: > - replace 'rc' with 'xattr_len' when calling integrity_digsig_verify() > with INTEGRITY_KEYRING_IMA for readability > > security/integrity/ima/ima_appraise.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c > index deec1804a00a..e8f520450895 100644 > --- a/security/integrity/ima/ima_appraise.c > +++ b/security/integrity/ima/ima_appraise.c > @@ -289,12 +289,21 @@ int ima_appraise_measurement(enum ima_hooks func, > case EVM_IMA_XATTR_DIGSIG: > set_bit(IMA_DIGSIG, &iint->atomic_flags); > rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, > - (const char *)xattr_value, rc, > + (const char *)xattr_value, > + xattr_len, > iint->ima_hash->digest, > iint->ima_hash->length); > if (rc == -EOPNOTSUPP) { > status = INTEGRITY_UNKNOWN; > - } else if (rc) { > + break; > + } > + if (rc && func == KEXEC_KERNEL_CHECK) > + rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM, > + (const char *)xattr_value, > + xattr_len, > + iint->ima_hash->digest, > + iint->ima_hash->length); If CONFIG_INTEGRITY_PLATFORM_KEYRING=n the second call to integrity_digsig_verify() above will always fail, and the audit message of failed signature verifications for KEXEC_KERNEL will always log the same rc value, which is whatever request_key() returns when asked to look for an inexistent keyring. Here is a patch which only performs the second try if the platform keyring is enabled. From d5fb94ab9eb13f6294f8dc44d1344cb85dfa41b8 Mon Sep 17 00:00:00 2001 From: Thiago Jung Bauermann <bauerman@linux.ibm.com> Date: Wed, 12 Dec 2018 16:02:09 -0200 Subject: [PATCH] ima: Only use the platform keyring if it's enabled Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com> --- security/integrity/ima/ima_appraise.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index e8f520450895..f6ac405daabb 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -297,7 +297,8 @@ int ima_appraise_measurement(enum ima_hooks func, status = INTEGRITY_UNKNOWN; break; } - if (rc && func == KEXEC_KERNEL_CHECK) + if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc && + func == KEXEC_KERNEL_CHECK) rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM, (const char *)xattr_value, xattr_len,
On Wed, 2018-12-12 at 16:14 -0200, Thiago Jung Bauermann wrote: [snip] > Subject: [PATCH] ima: Only use the platform keyring if it's enabled > > Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com> Good catch! Thanks. Mimi > --- > security/integrity/ima/ima_appraise.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c > index e8f520450895..f6ac405daabb 100644 > --- a/security/integrity/ima/ima_appraise.c > +++ b/security/integrity/ima/ima_appraise.c > @@ -297,7 +297,8 @@ int ima_appraise_measurement(enum ima_hooks func, > status = INTEGRITY_UNKNOWN; > break; > } > - if (rc && func == KEXEC_KERNEL_CHECK) > + if (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && rc && > + func == KEXEC_KERNEL_CHECK) > rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM, > (const char *)xattr_value, > xattr_len,
Nayna Jain <nayna@linux.ibm.com> writes: > On secure boot enabled systems, the bootloader verifies the kernel > image and possibly the initramfs signatures based on a set of keys. A > soft reboot(kexec) of the system, with the same kernel image and > initramfs, requires access to the original keys to verify the > signatures. > > This patch allows IMA-appraisal access to those original keys, now > loaded on the platform keyring, needed for verifying the kernel image > and initramfs signatures. > > Signed-off-by: Nayna Jain <nayna@linux.ibm.com> > Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> > Acked-by: Serge Hallyn <serge@hallyn.com> > - replace 'rc' with 'xattr_len' when calling integrity_digsig_verify() > with INTEGRITY_KEYRING_IMA for readability > Suggested-by: Serge Hallyn <serge@hallyn.com> > --- > Changelog: > > v2: > - replace 'rc' with 'xattr_len' when calling integrity_digsig_verify() > with INTEGRITY_KEYRING_IMA for readability > > security/integrity/ima/ima_appraise.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) With the change to only access the platform keyring when it is enabled: Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com> -- Thiago Jung Bauermann IBM Linux Technology Center
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c index deec1804a00a..e8f520450895 100644 --- a/security/integrity/ima/ima_appraise.c +++ b/security/integrity/ima/ima_appraise.c @@ -289,12 +289,21 @@ int ima_appraise_measurement(enum ima_hooks func, case EVM_IMA_XATTR_DIGSIG: set_bit(IMA_DIGSIG, &iint->atomic_flags); rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA, - (const char *)xattr_value, rc, + (const char *)xattr_value, + xattr_len, iint->ima_hash->digest, iint->ima_hash->length); if (rc == -EOPNOTSUPP) { status = INTEGRITY_UNKNOWN; - } else if (rc) { + break; + } + if (rc && func == KEXEC_KERNEL_CHECK) + rc = integrity_digsig_verify(INTEGRITY_KEYRING_PLATFORM, + (const char *)xattr_value, + xattr_len, + iint->ima_hash->digest, + iint->ima_hash->length); + if (rc) { cause = "invalid-signature"; status = INTEGRITY_FAIL; } else {