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

Pull integrity updates from James Morris:
 "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 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)"

* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  integrity: Remove references to module keyring
  ima: Use inode_is_open_for_write
  ima: Support platform keyring for kernel appraisal
  efi: Allow the "db" UEFI variable to be suppressed
  efi: Import certificates from UEFI Secure Boot
  efi: Add an EFI signature blob parser
  efi: Add EFI signature data types
  integrity: Load certs to the platform keyring
  integrity: Define a trusted platform keyring
  selftests/ima: kexec_load syscall test
  ima: don't measure/appraise files on efivarfs
  x86/ima: retry detecting secure boot mode
  docs: Extend trusted keys documentation for TPM 2.0
  x86/ima: define arch_get_ima_policy() for x86
  ima: add support for arch specific policies
  ima: refactor ima_init_policy()
  ima: prevent kexec_load syscall based on runtime secureboot flag
  x86/ima: define arch_ima_get_secureboot
  integrity: support new struct public_key_signature encoding field

4 files changed, 163 insertions, 53 deletions

diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index 13b446328dda..a18f8c6d13b5 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -157,6 +157,14 @@ config IMA_APPRAISE
 	  <http://linux-ima.sourceforge.net>
 	  If unsure, say N.
 
+config IMA_ARCH_POLICY
+        bool "Enable loading an IMA architecture specific policy"
+        depends on KEXEC_VERIFY_SIG || IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS
+        default n
+        help
+          This option enables loading an IMA architecture specific policy
+          based on run time secure boot flags.
+
 config IMA_APPRAISE_BUILD_POLICY
 	bool "IMA build time configured policy rules"
 	depends on IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS
@@ -217,7 +225,7 @@ config IMA_APPRAISE_REQUIRE_POLICY_SIGS
 
 config IMA_APPRAISE_BOOTPARAM
 	bool "ima_appraise boot parameter"
-	depends on IMA_APPRAISE
+	depends on IMA_APPRAISE && !IMA_ARCH_POLICY
 	default y
 	help
 	  This option enables the different "ima_appraise=" modes
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index 2e11e750a067..a2baa85ea2f5 100644
--- 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 {
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 616a88f95b92..4ffac4f5c647 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -105,7 +105,7 @@ static void ima_rdwr_violation_check(struct file *file,
 	} else {
 		if (must_measure)
 			set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
-		if ((atomic_read(&inode->i_writecount) > 0) && must_measure)
+		if (inode_is_open_for_write(inode) && must_measure)
 			send_writers = true;
 	}
 
@@ -507,20 +507,26 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
  */
 int ima_load_data(enum kernel_load_data_id id)
 {
-	bool sig_enforce;
+	bool ima_enforce, sig_enforce;
 
-	if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE)
-		return 0;
+	ima_enforce =
+		(ima_appraise & IMA_APPRAISE_ENFORCE) == IMA_APPRAISE_ENFORCE;
 
 	switch (id) {
 	case LOADING_KEXEC_IMAGE:
-		if (ima_appraise & IMA_APPRAISE_KEXEC) {
+		if (IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG)
+		    && arch_ima_get_secureboot()) {
+			pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
+			return -EACCES;
+		}
+
+		if (ima_enforce && (ima_appraise & IMA_APPRAISE_KEXEC)) {
 			pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
 			return -EACCES;	/* INTEGRITY_UNKNOWN */
 		}
 		break;
 	case LOADING_FIRMWARE:
-		if (ima_appraise & IMA_APPRAISE_FIRMWARE) {
+		if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE)) {
 			pr_err("Prevent firmware sysfs fallback loading.\n");
 			return -EACCES;	/* INTEGRITY_UNKNOWN */
 		}
@@ -528,7 +534,8 @@ int ima_load_data(enum kernel_load_data_id id)
 	case LOADING_MODULE:
 		sig_enforce = is_module_sig_enforced();
 
-		if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES)) {
+		if (ima_enforce && (!sig_enforce
+				    && (ima_appraise & IMA_APPRAISE_MODULES))) {
 			pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n");
 			return -EACCES;	/* INTEGRITY_UNKNOWN */
 		}
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index fcf5b2729063..8bc8a1c8cb3f 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();
 }