Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity into next-integrity

From Mimi:

In Linux 4.19, a new LSM hook named security_kernel_load_data was
upstreamed, allowing LSMs and IMA to prevent the kexec_load
syscall.  Different signature verification methods exist for verifying
the kexec'ed kernel image.  This pull request adds additional support
in IMA to prevent loading unsigned kernel images via the kexec_load
syscall, independently of the IMA policy rules, based on the runtime
"secure boot" flag.  An initial IMA kselftest is included.

In addition, this pull request defines a new, separate keyring named
".platform" for storing the preboot/firmware keys needed for verifying
the kexec'ed kernel image's signature and includes the associated IMA
kexec usage of the ".platform" keyring.

(David Howell's and Josh Boyer's patches for reading the
preboot/firmware keys, which were previously posted for a different
use case scenario, are included here.)

1 files changed, 128 insertions, 43 deletions

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 3778dc396193..fccd7b925498 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -20,6 +20,7 @@
 #include <linux/rculist.h>
 #include <linux/genhd.h>
 #include <linux/seq_file.h>
+#include <linux/ima.h>
 
 #include "ima.h"
 
@@ -58,6 +59,8 @@ enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
 
 enum policy_types { ORIGINAL_TCB = 1, DEFAULT_TCB };
 
+enum policy_rule_list { IMA_DEFAULT_POLICY = 1, IMA_CUSTOM_POLICY };
+
 struct ima_rule_entry {
 	struct list_head list;
 	int action;
@@ -104,7 +107,8 @@ static struct ima_rule_entry dont_measure_rules[] __ro_after_init = {
 	 .flags = IMA_FSMAGIC},
 	{.action = DONT_MEASURE, .fsmagic = CGROUP2_SUPER_MAGIC,
 	 .flags = IMA_FSMAGIC},
-	{.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC}
+	{.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
+	{.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC}
 };
 
 static struct ima_rule_entry original_measurement_rules[] __ro_after_init = {
@@ -147,6 +151,7 @@ static struct ima_rule_entry default_appraise_rules[] __ro_after_init = {
 	{.action = DONT_APPRAISE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE, .fsmagic = SMACK_MAGIC, .flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
+	{.action = DONT_APPRAISE, .fsmagic = EFIVARFS_MAGIC, .flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE, .fsmagic = CGROUP2_SUPER_MAGIC, .flags = IMA_FSMAGIC},
 #ifdef CONFIG_IMA_WRITE_POLICY
@@ -193,6 +198,9 @@ static struct ima_rule_entry secure_boot_rules[] __ro_after_init = {
 	 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
 };
 
+/* An array of architecture specific rules */
+struct ima_rule_entry *arch_policy_entry __ro_after_init;
+
 static LIST_HEAD(ima_default_rules);
 static LIST_HEAD(ima_policy_rules);
 static LIST_HEAD(ima_temp_rules);
@@ -473,6 +481,75 @@ static int ima_appraise_flag(enum ima_hooks func)
 	return 0;
 }
 
+static void add_rules(struct ima_rule_entry *entries, int count,
+		      enum policy_rule_list policy_rule)
+{
+	int i = 0;
+
+	for (i = 0; i < count; i++) {
+		struct ima_rule_entry *entry;
+
+		if (policy_rule & IMA_DEFAULT_POLICY)
+			list_add_tail(&entries[i].list, &ima_default_rules);
+
+		if (policy_rule & IMA_CUSTOM_POLICY) {
+			entry = kmemdup(&entries[i], sizeof(*entry),
+					GFP_KERNEL);
+			if (!entry)
+				continue;
+
+			list_add_tail(&entry->list, &ima_policy_rules);
+		}
+		if (entries[i].action == APPRAISE)
+			temp_ima_appraise |= ima_appraise_flag(entries[i].func);
+		if (entries[i].func == POLICY_CHECK)
+			temp_ima_appraise |= IMA_APPRAISE_POLICY;
+	}
+}
+
+static int ima_parse_rule(char *rule, struct ima_rule_entry *entry);
+
+static int __init ima_init_arch_policy(void)
+{
+	const char * const *arch_rules;
+	const char * const *rules;
+	int arch_entries = 0;
+	int i = 0;
+
+	arch_rules = arch_get_ima_policy();
+	if (!arch_rules)
+		return arch_entries;
+
+	/* Get number of rules */
+	for (rules = arch_rules; *rules != NULL; rules++)
+		arch_entries++;
+
+	arch_policy_entry = kcalloc(arch_entries + 1,
+				    sizeof(*arch_policy_entry), GFP_KERNEL);
+	if (!arch_policy_entry)
+		return 0;
+
+	/* Convert each policy string rules to struct ima_rule_entry format */
+	for (rules = arch_rules, i = 0; *rules != NULL; rules++) {
+		char rule[255];
+		int result;
+
+		result = strlcpy(rule, *rules, sizeof(rule));
+
+		INIT_LIST_HEAD(&arch_policy_entry[i].list);
+		result = ima_parse_rule(rule, &arch_policy_entry[i]);
+		if (result) {
+			pr_warn("Skipping unknown architecture policy rule: %s\n",
+				rule);
+			memset(&arch_policy_entry[i], 0,
+			       sizeof(*arch_policy_entry));
+			continue;
+		}
+		i++;
+	}
+	return i;
+}
+
 /**
  * ima_init_policy - initialize the default measure rules.
  *
@@ -481,68 +558,68 @@ static int ima_appraise_flag(enum ima_hooks func)
  */
 void __init ima_init_policy(void)
 {
-	int i, measure_entries, appraise_entries, secure_boot_entries;
+	int build_appraise_entries, arch_entries;
 
-	/* if !ima_policy set entries = 0 so we load NO default rules */
-	measure_entries = ima_policy ? ARRAY_SIZE(dont_measure_rules) : 0;
-	appraise_entries = ima_use_appraise_tcb ?
-			 ARRAY_SIZE(default_appraise_rules) : 0;
-	secure_boot_entries = ima_use_secure_boot ?
-			ARRAY_SIZE(secure_boot_rules) : 0;
-
-	for (i = 0; i < measure_entries; i++)
-		list_add_tail(&dont_measure_rules[i].list, &ima_default_rules);
+	/* if !ima_policy, we load NO default rules */
+	if (ima_policy)
+		add_rules(dont_measure_rules, ARRAY_SIZE(dont_measure_rules),
+			  IMA_DEFAULT_POLICY);
 
 	switch (ima_policy) {
 	case ORIGINAL_TCB:
-		for (i = 0; i < ARRAY_SIZE(original_measurement_rules); i++)
-			list_add_tail(&original_measurement_rules[i].list,
-				      &ima_default_rules);
+		add_rules(original_measurement_rules,
+			  ARRAY_SIZE(original_measurement_rules),
+			  IMA_DEFAULT_POLICY);
 		break;
 	case DEFAULT_TCB:
-		for (i = 0; i < ARRAY_SIZE(default_measurement_rules); i++)
-			list_add_tail(&default_measurement_rules[i].list,
-				      &ima_default_rules);
+		add_rules(default_measurement_rules,
+			  ARRAY_SIZE(default_measurement_rules),
+			  IMA_DEFAULT_POLICY);
 	default:
 		break;
 	}
 
 	/*
+	 * Based on runtime secure boot flags, insert arch specific measurement
+	 * and appraise rules requiring file signatures for both the initial
+	 * and custom policies, prior to other appraise rules.
+	 * (Highest priority)
+	 */
+	arch_entries = ima_init_arch_policy();
+	if (!arch_entries)
+		pr_info("No architecture policies found\n");
+	else
+		add_rules(arch_policy_entry, arch_entries,
+			  IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY);
+
+	/*
 	 * Insert the builtin "secure_boot" policy rules requiring file
-	 * signatures, prior to any other appraise rules.
+	 * signatures, prior to other appraise rules.
 	 */
-	for (i = 0; i < secure_boot_entries; i++) {
-		list_add_tail(&secure_boot_rules[i].list, &ima_default_rules);
-		temp_ima_appraise |=
-		    ima_appraise_flag(secure_boot_rules[i].func);
-	}
+	if (ima_use_secure_boot)
+		add_rules(secure_boot_rules, ARRAY_SIZE(secure_boot_rules),
+			  IMA_DEFAULT_POLICY);
 
 	/*
 	 * Insert the build time appraise rules requiring file signatures
 	 * for both the initial and custom policies, prior to other appraise
-	 * rules.
+	 * rules. As the secure boot rules includes all of the build time
+	 * rules, include either one or the other set of rules, but not both.
 	 */
-	for (i = 0; i < ARRAY_SIZE(build_appraise_rules); i++) {
-		struct ima_rule_entry *entry;
-
-		if (!secure_boot_entries)
-			list_add_tail(&build_appraise_rules[i].list,
-				      &ima_default_rules);
-
-		entry = kmemdup(&build_appraise_rules[i], sizeof(*entry),
-				GFP_KERNEL);
-		if (entry)
-			list_add_tail(&entry->list, &ima_policy_rules);
-		build_ima_appraise |=
-			ima_appraise_flag(build_appraise_rules[i].func);
+	build_appraise_entries = ARRAY_SIZE(build_appraise_rules);
+	if (build_appraise_entries) {
+		if (ima_use_secure_boot)
+			add_rules(build_appraise_rules, build_appraise_entries,
+				  IMA_CUSTOM_POLICY);
+		else
+			add_rules(build_appraise_rules, build_appraise_entries,
+				  IMA_DEFAULT_POLICY | IMA_CUSTOM_POLICY);
 	}
 
-	for (i = 0; i < appraise_entries; i++) {
-		list_add_tail(&default_appraise_rules[i].list,
-			      &ima_default_rules);
-		if (default_appraise_rules[i].func == POLICY_CHECK)
-			temp_ima_appraise |= IMA_APPRAISE_POLICY;
-	}
+	if (ima_use_appraise_tcb)
+		add_rules(default_appraise_rules,
+			  ARRAY_SIZE(default_appraise_rules),
+			  IMA_DEFAULT_POLICY);
 
 	ima_rules = &ima_default_rules;
 	ima_update_policy_flag();
@@ -576,6 +653,14 @@ void ima_update_policy(void)
 	if (ima_rules != policy) {
 		ima_policy_flag = 0;
 		ima_rules = policy;
+
+		/*
+		 * IMA architecture specific policy rules are specified
+		 * as strings and converted to an array of ima_entry_rules
+		 * on boot.  After loading a custom policy, free the
+		 * architecture specific rules stored as an array.
+		 */
+		kfree(arch_policy_entry);
 	}
 	ima_update_policy_flag();
 }