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

Pull security subsystem updates from James Morris:

 - kstrdup() return value fix from Eric Biggers

 - Add new security_load_data hook to differentiate security checking of
   kernel-loaded binaries in the case of there being no associated file
   descriptor, from Mimi Zohar.

 - Add ability to IMA to specify a policy at build-time, rather than
   just via command line params or by loading a custom policy, from
   Mimi.

 - Allow IMA and LSMs to prevent sysfs firmware load fallback (e.g. if
   using signed firmware), from Mimi.

 - Allow IMA to deny loading of kexec kernel images, as they cannot be
   measured by IMA, from Mimi.

* 'next-general' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  security: check for kstrdup() failure in lsm_append()
  security: export security_kernel_load_data function
  ima: based on policy warn about loading firmware (pre-allocated buffer)
  module: replace the existing LSM hook in init_module
  ima: add build time policy
  ima: based on policy require signed firmware (sysfs fallback)
  firmware: add call to LSM hook before firmware sysfs fallback
  ima: based on policy require signed kexec kernel images
  kexec: add call to LSM hook in original kexec_load syscall
  security: define new LSM hook named security_kernel_load_data
  MAINTAINERS: remove the outdated "LINUX SECURITY MODULE (LSM) FRAMEWORK" entry

MAINTAINERS

@@ -8342,11 +8342,6 @@ F:	Documentation/core-api/atomic_ops.rst
 F:	Documentation/core-api/refcount-vs-atomic.rst
 F:	Documentation/memory-barriers.txt
 
-LINUX SECURITY MODULE (LSM) FRAMEWORK
-M:	Chris Wright <chrisw@sous-sol.org>
-L:	linux-security-module@vger.kernel.org
-S:	Supported
-
 LIS3LV02D ACCELEROMETER DRIVER
 M:	Eric Piel <eric.piel@tremplin-utc.net>
 S:	Maintained

drivers/base/firmware_loader/fallback.c

@@ -651,6 +651,8 @@ static bool fw_force_sysfs_fallback(enum fw_opt opt_flags)
 
 static bool fw_run_sysfs_fallback(enum fw_opt opt_flags)
 {
+	int ret;
+
 	if (fw_fallback_config.ignore_sysfs_fallback) {
 		pr_info_once("Ignoring firmware sysfs fallback due to sysctl knob\n");
 		return false;
@@ -659,6 +661,11 @@ static bool fw_run_sysfs_fallback(enum fw_opt opt_flags)
 	if ((opt_flags & FW_OPT_NOFALLBACK))
 		return false;
 
+	/* Also permit LSMs and IMA to fail firmware sysfs fallback */
+	ret = security_kernel_load_data(LOADING_FIRMWARE);
+	if (ret < 0)
+		return ret;
+
 	return fw_force_sysfs_fallback(opt_flags);
 }
 

include/linux/ima.h

@@ -11,6 +11,7 @@
 #define _LINUX_IMA_H
 
 #include <linux/fs.h>
+#include <linux/security.h>
 #include <linux/kexec.h>
 struct linux_binprm;
 
@@ -19,6 +20,7 @@ extern int ima_bprm_check(struct linux_binprm *bprm);
 extern int ima_file_check(struct file *file, int mask);
 extern void ima_file_free(struct file *file);
 extern int ima_file_mmap(struct file *file, unsigned long prot);
+extern int ima_load_data(enum kernel_load_data_id id);
 extern int ima_read_file(struct file *file, enum kernel_read_file_id id);
 extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
 			      enum kernel_read_file_id id);
@@ -49,6 +51,11 @@ static inline int ima_file_mmap(struct file *file, unsigned long prot)
 	return 0;
 }
 
+static inline int ima_load_data(enum kernel_load_data_id id)
+{
+	return 0;
+}
+
 static inline int ima_read_file(struct file *file, enum kernel_read_file_id id)
 {
 	return 0;

include/linux/lsm_hooks.h

@@ -576,6 +576,10 @@
  *	userspace to load a kernel module with the given name.
  *	@kmod_name name of the module requested by the kernel
  *	Return 0 if successful.
+ * @kernel_load_data:
+ *	Load data provided by userspace.
+ *	@id kernel load data identifier
+ *	Return 0 if permission is granted.
  * @kernel_read_file:
  *	Read a file specified by userspace.
  *	@file contains the file structure pointing to the file being read
@@ -1582,6 +1586,7 @@ union security_list_options {
 	int (*kernel_act_as)(struct cred *new, u32 secid);
 	int (*kernel_create_files_as)(struct cred *new, struct inode *inode);
 	int (*kernel_module_request)(char *kmod_name);
+	int (*kernel_load_data)(enum kernel_load_data_id id);
 	int (*kernel_read_file)(struct file *file, enum kernel_read_file_id id);
 	int (*kernel_post_read_file)(struct file *file, char *buf, loff_t size,
 				     enum kernel_read_file_id id);
@@ -1872,6 +1877,7 @@ struct security_hook_heads {
 	struct hlist_head cred_getsecid;
 	struct hlist_head kernel_act_as;
 	struct hlist_head kernel_create_files_as;
+	struct hlist_head kernel_load_data;
 	struct hlist_head kernel_read_file;
 	struct hlist_head kernel_post_read_file;
 	struct hlist_head kernel_module_request;

include/linux/security.h

@@ -159,6 +159,27 @@ extern int mmap_min_addr_handler(struct ctl_table *table, int write,
 typedef int (*initxattrs) (struct inode *inode,
 			   const struct xattr *xattr_array, void *fs_data);
 
+
+/* Keep the kernel_load_data_id enum in sync with kernel_read_file_id */
+#define __data_id_enumify(ENUM, dummy) LOADING_ ## ENUM,
+#define __data_id_stringify(dummy, str) #str,
+
+enum kernel_load_data_id {
+	__kernel_read_file_id(__data_id_enumify)
+};
+
+static const char * const kernel_load_data_str[] = {
+	__kernel_read_file_id(__data_id_stringify)
+};
+
+static inline const char *kernel_load_data_id_str(enum kernel_load_data_id id)
+{
+	if ((unsigned)id >= LOADING_MAX_ID)
+		return kernel_load_data_str[LOADING_UNKNOWN];
+
+	return kernel_load_data_str[id];
+}
+
 #ifdef CONFIG_SECURITY
 
 struct security_mnt_opts {
@@ -320,6 +341,7 @@ void security_cred_getsecid(const struct cred *c, u32 *secid);
 int security_kernel_act_as(struct cred *new, u32 secid);
 int security_kernel_create_files_as(struct cred *new, struct inode *inode);
 int security_kernel_module_request(char *kmod_name);
+int security_kernel_load_data(enum kernel_load_data_id id);
 int security_kernel_read_file(struct file *file, enum kernel_read_file_id id);
 int security_kernel_post_read_file(struct file *file, char *buf, loff_t size,
 				   enum kernel_read_file_id id);
@@ -908,6 +930,11 @@ static inline int security_kernel_module_request(char *kmod_name)
 	return 0;
 }
 
+static inline int security_kernel_load_data(enum kernel_load_data_id id)
+{
+	return 0;
+}
+
 static inline int security_kernel_read_file(struct file *file,
 					    enum kernel_read_file_id id)
 {

kernel/kexec.c

@@ -11,6 +11,7 @@
 #include <linux/capability.h>
 #include <linux/mm.h>
 #include <linux/file.h>
+#include <linux/security.h>
 #include <linux/kexec.h>
 #include <linux/mutex.h>
 #include <linux/list.h>
@@ -195,10 +196,17 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
 static inline int kexec_load_check(unsigned long nr_segments,
 				   unsigned long flags)
 {
+	int result;
+
 	/* We only trust the superuser with rebooting the system. */
 	if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
 		return -EPERM;
 
+	/* Permit LSMs and IMA to fail the kexec */
+	result = security_kernel_load_data(LOADING_KEXEC_IMAGE);
+	if (result < 0)
+		return result;
+
 	/*
 	 * Verify we have a legal set of flags
 	 * This leaves us room for future extensions.

kernel/module.c

@@ -2876,7 +2876,7 @@ static int copy_module_from_user(const void __user *umod, unsigned long len,
 	if (info->len < sizeof(*(info->hdr)))
 		return -ENOEXEC;
 
-	err = security_kernel_read_file(NULL, READING_MODULE);
+	err = security_kernel_load_data(LOADING_MODULE);
 	if (err)
 		return err;
 

security/integrity/ima/Kconfig

@@ -156,6 +156,64 @@ config IMA_APPRAISE
 	  <http://linux-ima.sourceforge.net>
 	  If unsure, say N.
 
+config IMA_APPRAISE_BUILD_POLICY
+	bool "IMA build time configured policy rules"
+	depends on IMA_APPRAISE && INTEGRITY_ASYMMETRIC_KEYS
+	default n
+	help
+	  This option defines an IMA appraisal policy at build time, which
+	  is enforced at run time without having to specify a builtin
+	  policy name on the boot command line.  The build time appraisal
+	  policy rules persist after loading a custom policy.
+
+	  Depending on the rules configured, this policy may require kernel
+	  modules, firmware, the kexec kernel image, and/or the IMA policy
+	  to be signed.  Unsigned files might prevent the system from
+	  booting or applications from working properly.
+
+config IMA_APPRAISE_REQUIRE_FIRMWARE_SIGS
+	bool "Appraise firmware signatures"
+	depends on IMA_APPRAISE_BUILD_POLICY
+	default n
+	help
+	  This option defines a policy requiring all firmware to be signed,
+	  including the regulatory.db.  If both this option and
+	  CFG80211_REQUIRE_SIGNED_REGDB are enabled, then both signature
+	  verification methods are necessary.
+
+config IMA_APPRAISE_REQUIRE_KEXEC_SIGS
+	bool "Appraise kexec kernel image signatures"
+	depends on IMA_APPRAISE_BUILD_POLICY
+	default n
+	help
+	  Enabling this rule will require all kexec'ed kernel images to
+	  be signed and verified by a public key on the trusted IMA
+	  keyring.
+
+	  Kernel image signatures can not be verified by the original
+	  kexec_load syscall.  Enabling this rule will prevent its
+	  usage.
+
+config IMA_APPRAISE_REQUIRE_MODULE_SIGS
+	bool "Appraise kernel modules signatures"
+	depends on IMA_APPRAISE_BUILD_POLICY
+	default n
+	help
+	  Enabling this rule will require all kernel modules to be signed
+	  and verified by a public key on the trusted IMA keyring.
+
+	  Kernel module signatures can only be verified by IMA-appraisal,
+	  via the finit_module syscall. Enabling this rule will prevent
+	  the usage of the init_module syscall.
+
+config IMA_APPRAISE_REQUIRE_POLICY_SIGS
+	bool "Appraise IMA policy signature"
+	depends on IMA_APPRAISE_BUILD_POLICY
+	default n
+	help
+	  Enabling this rule will require the IMA policy to be signed and
+	  and verified by a key on the trusted IMA keyring.
+
 config IMA_APPRAISE_BOOTPARAM
 	bool "ima_appraise boot parameter"
 	depends on IMA_APPRAISE

security/integrity/ima/ima.h

@@ -232,6 +232,7 @@ int ima_policy_show(struct seq_file *m, void *v);
 #define IMA_APPRAISE_MODULES	0x08
 #define IMA_APPRAISE_FIRMWARE	0x10
 #define IMA_APPRAISE_POLICY	0x20
+#define IMA_APPRAISE_KEXEC	0x40
 
 #ifdef CONFIG_IMA_APPRAISE
 int ima_appraise_measurement(enum ima_hooks func,

security/integrity/ima/ima_main.c

@@ -429,16 +429,14 @@ void ima_post_path_mknod(struct dentry *dentry)
  */
 int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
 {
-	bool sig_enforce = is_module_sig_enforced();
-
-	if (!file && read_id == READING_MODULE) {
-		if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES) &&
-		    (ima_appraise & IMA_APPRAISE_ENFORCE)) {
-			pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n");
-			return -EACCES;	/* INTEGRITY_UNKNOWN */
-		}
-		return 0;	/* We rely on module signature checking */
-	}
+	/*
+	 * READING_FIRMWARE_PREALLOC_BUFFER
+	 *
+	 * Do devices using pre-allocated memory run the risk of the
+	 * firmware being accessible to the device prior to the completion
+	 * of IMA's signature verification any more than when using two
+	 * buffers?
+	 */
 	return 0;
 }
 
@@ -472,13 +470,12 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
 
 	if (!file && read_id == READING_FIRMWARE) {
 		if ((ima_appraise & IMA_APPRAISE_FIRMWARE) &&
-		    (ima_appraise & IMA_APPRAISE_ENFORCE))
+		    (ima_appraise & IMA_APPRAISE_ENFORCE)) {
+			pr_err("Prevent firmware loading_store.\n");
 			return -EACCES;	/* INTEGRITY_UNKNOWN */
-		return 0;
 		}
-
-	if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */
 		return 0;
+	}
 
 	/* permit signed certs */
 	if (!file && read_id == READING_X509_CERTIFICATE)
@@ -496,6 +493,49 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
 				   MAY_READ, func);
 }
 
+/**
+ * ima_load_data - appraise decision based on policy
+ * @id: kernel load data caller identifier
+ *
+ * Callers of this LSM hook can not measure, appraise, or audit the
+ * data provided by userspace.  Enforce policy rules requring a file
+ * signature (eg. kexec'ed kernel image).
+ *
+ * For permission return 0, otherwise return -EACCES.
+ */
+int ima_load_data(enum kernel_load_data_id id)
+{
+	bool sig_enforce;
+
+	if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE)
+		return 0;
+
+	switch (id) {
+	case LOADING_KEXEC_IMAGE:
+		if (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) {
+			pr_err("Prevent firmware sysfs fallback loading.\n");
+			return -EACCES;	/* INTEGRITY_UNKNOWN */
+		}
+		break;
+	case LOADING_MODULE:
+		sig_enforce = is_module_sig_enforced();
+
+		if (!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 */
+		}
+	default:
+		break;
+	}
+	return 0;
+}
+
 static int __init init_ima(void)
 {
 	int error;

security/integrity/ima/ima_policy.c

@@ -49,6 +49,7 @@
 
 int ima_policy_flag;
 static int temp_ima_appraise;
+static int build_ima_appraise __ro_after_init;
 
 #define MAX_LSM_RULES 6
 enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
@@ -162,6 +163,25 @@ static struct ima_rule_entry default_appraise_rules[] __ro_after_init = {
 #endif
 };
 
+static struct ima_rule_entry build_appraise_rules[] __ro_after_init = {
+#ifdef CONFIG_IMA_APPRAISE_REQUIRE_MODULE_SIGS
+	{.action = APPRAISE, .func = MODULE_CHECK,
+	 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
+#endif
+#ifdef CONFIG_IMA_APPRAISE_REQUIRE_FIRMWARE_SIGS
+	{.action = APPRAISE, .func = FIRMWARE_CHECK,
+	 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
+#endif
+#ifdef CONFIG_IMA_APPRAISE_REQUIRE_KEXEC_SIGS
+	{.action = APPRAISE, .func = KEXEC_KERNEL_CHECK,
+	 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
+#endif
+#ifdef CONFIG_IMA_APPRAISE_REQUIRE_POLICY_SIGS
+	{.action = APPRAISE, .func = POLICY_CHECK,
+	 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
+#endif
+};
+
 static struct ima_rule_entry secure_boot_rules[] __ro_after_init = {
 	{.action = APPRAISE, .func = MODULE_CHECK,
 	 .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
@@ -435,7 +455,7 @@ void ima_update_policy_flag(void)
 			ima_policy_flag |= entry->action;
 	}
 
-	ima_appraise |= temp_ima_appraise;
+	ima_appraise |= (build_ima_appraise | temp_ima_appraise);
 	if (!ima_appraise)
 		ima_policy_flag &= ~IMA_APPRAISE;
 }
@@ -448,6 +468,8 @@ static int ima_appraise_flag(enum ima_hooks func)
 		return IMA_APPRAISE_FIRMWARE;
 	else if (func == POLICY_CHECK)
 		return IMA_APPRAISE_POLICY;
+	else if (func == KEXEC_KERNEL_CHECK)
+		return IMA_APPRAISE_KEXEC;
 	return 0;
 }
 
@@ -486,8 +508,8 @@ void __init ima_init_policy(void)
 	}
 
 	/*
-	 * Insert the appraise rules requiring file signatures, prior to
-	 * any other appraise rules.
+	 * Insert the builtin "secure_boot" policy rules requiring file
+	 * signatures, prior to any other appraise rules.
 	 */
 	for (i = 0; i < secure_boot_entries; i++) {
 		list_add_tail(&secure_boot_rules[i].list, &ima_default_rules);
@@ -495,6 +517,26 @@ void __init ima_init_policy(void)
 		    ima_appraise_flag(secure_boot_rules[i].func);
 	}
 
+	/*
+	 * Insert the build time appraise rules requiring file signatures
+	 * for both the initial and custom policies, prior to other appraise
+	 * rules.
+	 */
+	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);
+	}
+
 	for (i = 0; i < appraise_entries; i++) {
 		list_add_tail(&default_appraise_rules[i].list,
 			      &ima_default_rules);

security/loadpin/loadpin.c

@@ -173,9 +173,15 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id)
 	return 0;
 }
 
+static int loadpin_load_data(enum kernel_load_data_id id)
+{
+	return loadpin_read_file(NULL, (enum kernel_read_file_id) id);
+}
+
 static struct security_hook_list loadpin_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(sb_free_security, loadpin_sb_free_security),
 	LSM_HOOK_INIT(kernel_read_file, loadpin_read_file),
+	LSM_HOOK_INIT(kernel_load_data, loadpin_load_data),
 };
 
 void __init loadpin_add_hooks(void)

security/security.c

@@ -118,6 +118,8 @@ static int lsm_append(char *new, char **result)
 
 	if (*result == NULL) {
 		*result = kstrdup(new, GFP_KERNEL);
+		if (*result == NULL)
+			return -ENOMEM;
 	} else {
 		/* Check if it is the last registered name */
 		if (match_last_lsm(*result, new))
@@ -1056,6 +1058,17 @@ int security_kernel_post_read_file(struct file *file, char *buf, loff_t size,
 }
 EXPORT_SYMBOL_GPL(security_kernel_post_read_file);
 
+int security_kernel_load_data(enum kernel_load_data_id id)
+{
+	int ret;
+
+	ret = call_int_hook(kernel_load_data, 0, id);
+	if (ret)
+		return ret;
+	return ima_load_data(id);
+}
+EXPORT_SYMBOL_GPL(security_kernel_load_data);
+
 int security_task_fix_setuid(struct cred *new, const struct cred *old,
 			     int flags)
 {

security/selinux/hooks.c

@@ -4073,6 +4073,20 @@ static int selinux_kernel_read_file(struct file *file,
 	return rc;
 }
 
+static int selinux_kernel_load_data(enum kernel_load_data_id id)
+{
+	int rc = 0;
+
+	switch (id) {
+	case LOADING_MODULE:
+		rc = selinux_kernel_module_from_file(NULL);
+	default:
+		break;
+	}
+
+	return rc;
+}
+
 static int selinux_task_setpgid(struct task_struct *p, pid_t pgid)
 {
 	return avc_has_perm(&selinux_state,
@@ -6972,6 +6986,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 	LSM_HOOK_INIT(kernel_act_as, selinux_kernel_act_as),
 	LSM_HOOK_INIT(kernel_create_files_as, selinux_kernel_create_files_as),
 	LSM_HOOK_INIT(kernel_module_request, selinux_kernel_module_request),
+	LSM_HOOK_INIT(kernel_load_data, selinux_kernel_load_data),
 	LSM_HOOK_INIT(kernel_read_file, selinux_kernel_read_file),
 	LSM_HOOK_INIT(task_setpgid, selinux_task_setpgid),
 	LSM_HOOK_INIT(task_getpgid, selinux_task_getpgid),