integrity: Always reference the blacklist keyring with appraisal

Commit 273df864cf746 ("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>

diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index 49db0ff..c238518 100644 (file)
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -57,9 +57,9 @@ Description:
                                stored in security.ima xattr. Requires
                                specifying "digest_type=verity" first.)
 
-                       appraise_flag:= [check_blacklist]
-                       Currently, blacklist check is only for files signed with appended
-                       signature.
+                       appraise_flag:= [check_blacklist] (deprecated)
+                       Setting the check_blacklist flag is no longer necessary.
+                       All appraisal functions set it by default.
                        digest_type:= verity
                            Require fs-verity's file digest instead of the
                            regular IMA file hash.

diff --git a/arch/powerpc/kernel/ima_arch.c b/arch/powerpc/kernel/ima_arch.c
index 957abd5..b7029be 100644 (file)
--- a/arch/powerpc/kernel/ima_arch.c
+++ b/arch/powerpc/kernel/ima_arch.c
@@ -23,9 +23,9 @@ bool arch_ima_get_secureboot(void)
  * is not enabled.
  */
 static const char *const secure_rules[] = {
-       "appraise func=KEXEC_KERNEL_CHECK appraise_flag=check_blacklist appraise_type=imasig|modsig",
+       "appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig",
 #ifndef CONFIG_MODULE_SIG
-       "appraise func=MODULE_CHECK appraise_flag=check_blacklist appraise_type=imasig|modsig",
+       "appraise func=MODULE_CHECK appraise_type=imasig|modsig",
 #endif
        NULL
 };
@@ -49,9 +49,9 @@ static const char *const trusted_rules[] = {
 static const char *const secure_and_trusted_rules[] = {
        "measure func=KEXEC_KERNEL_CHECK template=ima-modsig",
        "measure func=MODULE_CHECK template=ima-modsig",
-       "appraise func=KEXEC_KERNEL_CHECK appraise_flag=check_blacklist appraise_type=imasig|modsig",
+       "appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig",
 #ifndef CONFIG_MODULE_SIG
-       "appraise func=MODULE_CHECK appraise_flag=check_blacklist appraise_type=imasig|modsig",
+       "appraise func=MODULE_CHECK appraise_type=imasig|modsig",
 #endif
        NULL
 };

diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 491c1ac..870dde6 100644 (file)
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -458,11 +458,13 @@ int ima_check_blacklist(struct integrity_iint_cache *iint,
                ima_get_modsig_digest(modsig, &hash_algo, &digest, &digestsize);
 
                rc = is_binary_blacklisted(digest, digestsize);
-               if ((rc == -EPERM) && (iint->flags & IMA_MEASURE))
-                       process_buffer_measurement(&nop_mnt_idmap, NULL, digest, digestsize,
-                                                  "blacklisted-hash", NONE,
-                                                  pcr, NULL, false, NULL, 0);
-       }
+       } else if (iint->flags & IMA_DIGSIG_REQUIRED && iint->ima_hash)
+               rc = is_binary_blacklisted(iint->ima_hash->digest, iint->ima_hash->length);
+
+       if ((rc == -EPERM) && (iint->flags & IMA_MEASURE))
+               process_buffer_measurement(&nop_mnt_idmap, NULL, digest, digestsize,
+                                          "blacklisted-hash", NONE,
+                                          pcr, NULL, false, NULL, 0);
 
        return rc;
 }

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index c9b3bd8..69452b7 100644 (file)
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -1280,7 +1280,7 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
                                     IMA_FSNAME | IMA_GID | IMA_EGID |
                                     IMA_FGROUP | IMA_DIGSIG_REQUIRED |
                                     IMA_PERMIT_DIRECTIO | IMA_VALIDATE_ALGOS |
-                                    IMA_VERITY_REQUIRED))
+                                    IMA_CHECK_BLACKLIST | IMA_VERITY_REQUIRED))
                        return false;
 
                break;
@@ -1355,7 +1355,7 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
 
        /* Ensure that combinations of flags are compatible with each other */
        if (entry->flags & IMA_CHECK_BLACKLIST &&
-           !(entry->flags & IMA_MODSIG_ALLOWED))
+           !(entry->flags & IMA_DIGSIG_REQUIRED))
                return false;
 
        /*
@@ -1803,11 +1803,11 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
                                if (entry->flags & IMA_VERITY_REQUIRED)
                                        result = -EINVAL;
                                else
-                                       entry->flags |= IMA_DIGSIG_REQUIRED;
+                                       entry->flags |= IMA_DIGSIG_REQUIRED | IMA_CHECK_BLACKLIST;
                        } else if (strcmp(args[0].from, "sigv3") == 0) {
                                /* Only fsverity supports sigv3 for now */
                                if (entry->flags & IMA_VERITY_REQUIRED)
-                                       entry->flags |= IMA_DIGSIG_REQUIRED;
+                                       entry->flags |= IMA_DIGSIG_REQUIRED | IMA_CHECK_BLACKLIST;
                                else
                                        result = -EINVAL;
                        } else if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
@@ -1816,18 +1816,13 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
                                        result = -EINVAL;
                                else
                                        entry->flags |= IMA_DIGSIG_REQUIRED |
-                                               IMA_MODSIG_ALLOWED;
+                                               IMA_MODSIG_ALLOWED | IMA_CHECK_BLACKLIST;
                        } else {
                                result = -EINVAL;
                        }
                        break;
                case Opt_appraise_flag:
                        ima_log_string(ab, "appraise_flag", args[0].from);
-                       if (IS_ENABLED(CONFIG_IMA_APPRAISE_MODSIG) &&
-                           strstr(args[0].from, "blacklist"))
-                               entry->flags |= IMA_CHECK_BLACKLIST;
-                       else
-                               result = -EINVAL;
                        break;
                case Opt_appraise_algos:
                        ima_log_string(ab, "appraise_algos", args[0].from);
@@ -2271,8 +2266,6 @@ int ima_policy_show(struct seq_file *m, void *v)
        }
        if (entry->flags & IMA_VERITY_REQUIRED)
                seq_puts(m, "digest_type=verity ");
-       if (entry->flags & IMA_CHECK_BLACKLIST)
-               seq_puts(m, "appraise_flag=check_blacklist ");
        if (entry->flags & IMA_PERMIT_DIRECTIO)
                seq_puts(m, "permit_directio ");
        rcu_read_unlock();