ima: Support platform keyring for kernel appraisal

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.

[[email protected]: only use platform keyring if it's enabled (Thiago)]
Signed-off-by: Nayna Jain <[email protected]>
Reviewed-by: Mimi Zohar <[email protected]>
Acked-by: Serge Hallyn <[email protected]>
Reviewed-by: James Morris <[email protected]>
Reviewed-by: Thiago Jung Bauermann <[email protected]>
Signed-off-by: Mimi Zohar <[email protected]>

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index deec1804a00aa488d02b307371cfc18475127bc3..f6ac405daabbe3b7b0ec9faa538910cf4d706bd3 100644 (file)
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -289,12 +289,22 @@ 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 (IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING) && 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 {