[PATCH V35 00/29] Kernel lockdown functionality

[PATCH V35 00/29] Kernel lockdown functionality

[Matthew Garrett]

Minor updates to the previous patchset to take some review comments into
account - no significant changes in functionality, other than that the
eBPF patch now only disables the kernel read functions as requested.

[PATCH V35 01/29] security: Support early LSMs

[Matthew Garrett]

The lockdown module is intended to allow for kernels to be locked down
early in boot - sufficiently early that we don't have the ability to
kmalloc() yet. Add support for early initialisation of some LSMs, and
then add them to the list of names when we do full initialisation later.
Early LSMs are initialised in link order and cannot be overridden via
boot parameters, and cannot make use of kmalloc() (since the allocator
isn't initialised yet).

Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
---
 include/asm-generic/vmlinux.lds.h |  8 ++++-
 include/linux/lsm_hooks.h         |  6 ++++
 include/linux/security.h          |  1 +
 init/main.c                       |  1 +
 security/security.c               | 50 ++++++++++++++++++++++++++-----
 5 files changed, 57 insertions(+), 9 deletions(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index ca42182992a5..6cc6174a2a4c 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -215,8 +215,13 @@
 			__start_lsm_info = .;				\
 			KEEP(*(.lsm_info.init))				\
 			__end_lsm_info = .;
+#define EARLY_LSM_TABLE()	. = ALIGN(8);				\
+			__start_early_lsm_info = .;			\
+			KEEP(*(.early_lsm_info.init))			\
+			__end_early_lsm_info = .;
 #else
 #define LSM_TABLE()
+#define EARLY_LSM_TABLE()
 #endif
 
 #define ___OF_TABLE(cfg, name)	_OF_TABLE_##cfg(name)
@@ -616,7 +621,8 @@
 	ACPI_PROBE_TABLE(irqchip)					\
 	ACPI_PROBE_TABLE(timer)						\
 	EARLYCON_TABLE()						\
-	LSM_TABLE()
+	LSM_TABLE()							\
+	EARLY_LSM_TABLE()
 
 #define INIT_TEXT							\
 	*(.init.text .init.text.*)					\
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index df1318d85f7d..aebb0e032072 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -2104,12 +2104,18 @@ struct lsm_info {
 };
 
 extern struct lsm_info __start_lsm_info[], __end_lsm_info[];
+extern struct lsm_info __start_early_lsm_info[], __end_early_lsm_info[];
 
 #define DEFINE_LSM(lsm)							\
 	static struct lsm_info __lsm_##lsm				\
 		__used __section(.lsm_info.init)			\
 		__aligned(sizeof(unsigned long))
 
+#define DEFINE_EARLY_LSM(lsm)						\
+	static struct lsm_info __early_lsm_##lsm			\
+		__used __section(.early_lsm_info.init)			\
+		__aligned(sizeof(unsigned long))
+
 #ifdef CONFIG_SECURITY_SELINUX_DISABLE
 /*
  * Assuring the safety of deleting a security module is up to
diff --git a/include/linux/security.h b/include/linux/security.h
index 5f7441abbf42..66a2fcbe6ab0 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -195,6 +195,7 @@ int unregister_blocking_lsm_notifier(struct notifier_block *nb);
 
 /* prototypes */
 extern int security_init(void);
+extern int early_security_init(void);
 
 /* Security operations */
 int security_binder_set_context_mgr(struct task_struct *mgr);
diff --git a/init/main.c b/init/main.c
index ff5803b0841c..0fefca3fd43c 100644
--- a/init/main.c
+++ b/init/main.c
@@ -593,6 +593,7 @@ asmlinkage __visible void __init start_kernel(void)
 	boot_cpu_init();
 	page_address_init();
 	pr_notice("%s", linux_banner);
+	early_security_init();
 	setup_arch(&command_line);
 	mm_init_cpumask(&init_mm);
 	setup_command_line(command_line);
diff --git a/security/security.c b/security/security.c
index 250ee2d76406..90f1e291c800 100644
--- a/security/security.c
+++ b/security/security.c
@@ -33,6 +33,7 @@
 
 /* How many LSMs were built into the kernel? */
 #define LSM_COUNT (__end_lsm_info - __start_lsm_info)
+#define EARLY_LSM_COUNT (__end_early_lsm_info - __start_early_lsm_info)
 
 struct security_hook_heads security_hook_heads __lsm_ro_after_init;
 static BLOCKING_NOTIFIER_HEAD(blocking_lsm_notifier_chain);
@@ -277,6 +278,8 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
 static void __init lsm_early_cred(struct cred *cred);
 static void __init lsm_early_task(struct task_struct *task);
 
+static int lsm_append(const char *new, char **result);
+
 static void __init ordered_lsm_init(void)
 {
 	struct lsm_info **lsm;
@@ -323,6 +326,26 @@ static void __init ordered_lsm_init(void)
 	kfree(ordered_lsms);
 }
 
+int __init early_security_init(void)
+{
+	int i;
+	struct hlist_head *list = (struct hlist_head *) &security_hook_heads;
+	struct lsm_info *lsm;
+
+	for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct hlist_head);
+	     i++)
+		INIT_HLIST_HEAD(&list[i]);
+
+	for (lsm = __start_early_lsm_info; lsm < __end_early_lsm_info; lsm++) {
+		if (!lsm->enabled)
+			lsm->enabled = &lsm_enabled_true;
+		prepare_lsm(lsm);
+		initialize_lsm(lsm);
+	}
+
+	return 0;
+}
+
 /**
  * security_init - initializes the security framework
  *
@@ -330,14 +353,18 @@ static void __init ordered_lsm_init(void)
  */
 int __init security_init(void)
 {
-	int i;
-	struct hlist_head *list = (struct hlist_head *) &security_hook_heads;
+	struct lsm_info *lsm;
 
 	pr_info("Security Framework initializing\n");
 
-	for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct hlist_head);
-	     i++)
-		INIT_HLIST_HEAD(&list[i]);
+	/*
+	 * Append the names of the early LSM modules now that kmalloc() is
+	 * available
+	 */
+	for (lsm = __start_early_lsm_info; lsm < __end_early_lsm_info; lsm++) {
+		if (lsm->enabled)
+			lsm_append(lsm->name, &lsm_names);
+	}
 
 	/* Load LSMs in specified order. */
 	ordered_lsm_init();
@@ -384,7 +411,7 @@ static bool match_last_lsm(const char *list, const char *lsm)
 	return !strcmp(last, lsm);
 }
 
-static int lsm_append(char *new, char **result)
+static int lsm_append(const char *new, char **result)
 {
 	char *cp;
 
@@ -422,8 +449,15 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count,
 		hooks[i].lsm = lsm;
 		hlist_add_tail_rcu(&hooks[i].list, hooks[i].head);
 	}
-	if (lsm_append(lsm, &lsm_names) < 0)
-		panic("%s - Cannot get early memory.\n", __func__);
+
+	/*
+	 * Don't try to append during early_security_init(), we'll come back
+	 * and fix this up afterwards.
+	 */
+	if (slab_is_available()) {
+		if (lsm_append(lsm, &lsm_names) < 0)
+			panic("%s - Cannot get early memory.\n", __func__);
+	}
 }
 
 int call_blocking_lsm_notifier(enum lsm_event event, void *data)
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 02/29] security: Add a "locked down" LSM hook

[Matthew Garrett]

Add a mechanism to allow LSMs to make a policy decision around whether
kernel functionality that would allow tampering with or examining the
runtime state of the kernel should be permitted.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
---
 include/linux/lsm_hooks.h |  2 ++
 include/linux/security.h  | 32 ++++++++++++++++++++++++++++++++
 security/security.c       |  6 ++++++
 3 files changed, 40 insertions(+)

diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index aebb0e032072..29c22cf40113 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1807,6 +1807,7 @@ union security_list_options {
 	int (*bpf_prog_alloc_security)(struct bpf_prog_aux *aux);
 	void (*bpf_prog_free_security)(struct bpf_prog_aux *aux);
 #endif /* CONFIG_BPF_SYSCALL */
+	int (*locked_down)(enum lockdown_reason what);
 };
 
 struct security_hook_heads {
@@ -2046,6 +2047,7 @@ struct security_hook_heads {
 	struct hlist_head bpf_prog_alloc_security;
 	struct hlist_head bpf_prog_free_security;
 #endif /* CONFIG_BPF_SYSCALL */
+	struct hlist_head locked_down;
 } __randomize_layout;
 
 /*
diff --git a/include/linux/security.h b/include/linux/security.h
index 66a2fcbe6ab0..c2b1204e8e26 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -77,6 +77,33 @@ enum lsm_event {
 	LSM_POLICY_CHANGE,
 };
 
+/*
+ * These are reasons that can be passed to the security_locked_down()
+ * LSM hook. Lockdown reasons that protect kernel integrity (ie, the
+ * ability for userland to modify kernel code) are placed before
+ * LOCKDOWN_INTEGRITY_MAX.  Lockdown reasons that protect kernel
+ * confidentiality (ie, the ability for userland to extract
+ * information from the running kernel that would otherwise be
+ * restricted) are placed before LOCKDOWN_CONFIDENTIALITY_MAX.
+ *
+ * LSM authors should note that the semantics of any given lockdown
+ * reason are not guaranteed to be stable - the same reason may block
+ * one set of features in one kernel release, and a slightly different
+ * set of features in a later kernel release. LSMs that seek to expose
+ * lockdown policy at any level of granularity other than "none",
+ * "integrity" or "confidentiality" are responsible for either
+ * ensuring that they expose a consistent level of functionality to
+ * userland, or ensuring that userland is aware that this is
+ * potentially a moving target. It is easy to misuse this information
+ * in a way that could break userspace. Please be careful not to do
+ * so.
+ */
+enum lockdown_reason {
+	LOCKDOWN_NONE,
+	LOCKDOWN_INTEGRITY_MAX,
+	LOCKDOWN_CONFIDENTIALITY_MAX,
+};
+
 /* These functions are in security/commoncap.c */
 extern int cap_capable(const struct cred *cred, struct user_namespace *ns,
 		       int cap, unsigned int opts);
@@ -393,6 +420,7 @@ void security_inode_invalidate_secctx(struct inode *inode);
 int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen);
 int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen);
 int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen);
+int security_locked_down(enum lockdown_reason what);
 #else /* CONFIG_SECURITY */
 
 static inline int call_blocking_lsm_notifier(enum lsm_event event, void *data)
@@ -1205,6 +1233,10 @@ static inline int security_inode_getsecctx(struct inode *inode, void **ctx, u32
 {
 	return -EOPNOTSUPP;
 }
+static inline int security_locked_down(enum lockdown_reason what)
+{
+	return 0;
+}
 #endif	/* CONFIG_SECURITY */
 
 #ifdef CONFIG_SECURITY_NETWORK
diff --git a/security/security.c b/security/security.c
index 90f1e291c800..ce6c945bf347 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2392,3 +2392,9 @@ void security_bpf_prog_free(struct bpf_prog_aux *aux)
 	call_void_hook(bpf_prog_free_security, aux);
 }
 #endif /* CONFIG_BPF_SYSCALL */
+
+int security_locked_down(enum lockdown_reason what)
+{
+	return call_int_hook(locked_down, 0, what);
+}
+EXPORT_SYMBOL(security_locked_down);
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 03/29] security: Add a static lockdown policy LSM

[Matthew Garrett]

While existing LSMs can be extended to handle lockdown policy,
distributions generally want to be able to apply a straightforward
static policy. This patch adds a simple LSM that can be configured to
reject either integrity or all lockdown queries, and can be configured
at runtime (through securityfs), boot time (via a kernel parameter) or
build time (via a kconfig option). Based on initial code by David
Howells.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: David Howells <dhowells@redhat.com>
---
 .../admin-guide/kernel-parameters.txt         |   9 +
 include/linux/security.h                      |   3 +
 security/Kconfig                              |  11 +-
 security/Makefile                             |   2 +
 security/lockdown/Kconfig                     |  47 +++++
 security/lockdown/Makefile                    |   1 +
 security/lockdown/lockdown.c                  | 172 ++++++++++++++++++
 7 files changed, 240 insertions(+), 5 deletions(-)
 create mode 100644 security/lockdown/Kconfig
 create mode 100644 security/lockdown/Makefile
 create mode 100644 security/lockdown/lockdown.c

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 099c5a4be95b..95acd46fd891 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2248,6 +2248,15 @@
 	lockd.nlm_udpport=M	[NFS] Assign UDP port.
 			Format: <integer>
 
+	lockdown=	[SECURITY]
+			{ integrity | confidentiality }
+			Enable the kernel lockdown feature. If set to
+			integrity, kernel features that allow userland to
+			modify the running kernel are disabled. If set to
+			confidentiality, kernel features that allow userland
+			to extract confidential information from the kernel
+			are also disabled.
+
 	locktorture.nreaders_stress= [KNL]
 			Set the number of locking read-acquisition kthreads.
 			Defaults to being automatically set based on the
diff --git a/include/linux/security.h b/include/linux/security.h
index c2b1204e8e26..54a0532ec12f 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -97,6 +97,9 @@ enum lsm_event {
  * potentially a moving target. It is easy to misuse this information
  * in a way that could break userspace. Please be careful not to do
  * so.
+ *
+ * If you add to this, remember to extend lockdown_reasons in
+ * security/lockdown/lockdown.c.
  */
 enum lockdown_reason {
 	LOCKDOWN_NONE,
diff --git a/security/Kconfig b/security/Kconfig
index 06a30851511a..967e86fc415a 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -237,6 +237,7 @@ source "security/apparmor/Kconfig"
 source "security/loadpin/Kconfig"
 source "security/yama/Kconfig"
 source "security/safesetid/Kconfig"
+source "security/lockdown/Kconfig"
 
 source "security/integrity/Kconfig"
 
@@ -276,11 +277,11 @@ endchoice
 
 config LSM
 	string "Ordered list of enabled LSMs"
-	default "yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor" if DEFAULT_SECURITY_SMACK
-	default "yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo" if DEFAULT_SECURITY_APPARMOR
-	default "yama,loadpin,safesetid,integrity,tomoyo" if DEFAULT_SECURITY_TOMOYO
-	default "yama,loadpin,safesetid,integrity" if DEFAULT_SECURITY_DAC
-	default "yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor"
+	default "lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor" if DEFAULT_SECURITY_SMACK
+	default "lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo" if DEFAULT_SECURITY_APPARMOR
+	default "lockdown,yama,loadpin,safesetid,integrity,tomoyo" if DEFAULT_SECURITY_TOMOYO
+	default "lockdown,yama,loadpin,safesetid,integrity" if DEFAULT_SECURITY_DAC
+	default "lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor"
 	help
 	  A comma-separated list of LSMs, in initialization order.
 	  Any LSMs left off this list will be ignored. This can be
diff --git a/security/Makefile b/security/Makefile
index c598b904938f..be1dd9d2cb2f 100644
--- a/security/Makefile
+++ b/security/Makefile
@@ -11,6 +11,7 @@ subdir-$(CONFIG_SECURITY_APPARMOR)	+= apparmor
 subdir-$(CONFIG_SECURITY_YAMA)		+= yama
 subdir-$(CONFIG_SECURITY_LOADPIN)	+= loadpin
 subdir-$(CONFIG_SECURITY_SAFESETID)    += safesetid
+subdir-$(CONFIG_SECURITY_LOCKDOWN_LSM)	+= lockdown
 
 # always enable default capabilities
 obj-y					+= commoncap.o
@@ -27,6 +28,7 @@ obj-$(CONFIG_SECURITY_APPARMOR)		+= apparmor/
 obj-$(CONFIG_SECURITY_YAMA)		+= yama/
 obj-$(CONFIG_SECURITY_LOADPIN)		+= loadpin/
 obj-$(CONFIG_SECURITY_SAFESETID)       += safesetid/
+obj-$(CONFIG_SECURITY_LOCKDOWN_LSM)	+= lockdown/
 obj-$(CONFIG_CGROUP_DEVICE)		+= device_cgroup.o
 
 # Object integrity file lists
diff --git a/security/lockdown/Kconfig b/security/lockdown/Kconfig
new file mode 100644
index 000000000000..7374ba76d8eb
--- /dev/null
+++ b/security/lockdown/Kconfig
@@ -0,0 +1,47 @@
+config SECURITY_LOCKDOWN_LSM
+	bool "Basic module for enforcing kernel lockdown"
+	depends on SECURITY
+	help
+	  Build support for an LSM that enforces a coarse kernel lockdown
+	  behaviour.
+
+config SECURITY_LOCKDOWN_LSM_EARLY
+	bool "Enable lockdown LSM early in init"
+	depends on SECURITY_LOCKDOWN_LSM
+	help
+	  Enable the lockdown LSM early in boot. This is necessary in order
+	  to ensure that lockdown enforcement can be carried out on kernel
+	  boot parameters that are otherwise parsed before the security
+	  subsystem is fully initialised. If enabled, lockdown will
+	  unconditionally be called before any other LSMs.
+
+choice
+	prompt "Kernel default lockdown mode"
+	default LOCK_DOWN_KERNEL_FORCE_NONE
+	depends on SECURITY_LOCKDOWN_LSM
+	help
+	  The kernel can be configured to default to differing levels of
+	  lockdown.
+
+config LOCK_DOWN_KERNEL_FORCE_NONE
+	bool "None"
+	help
+	  No lockdown functionality is enabled by default. Lockdown may be
+	  enabled via the kernel commandline or /sys/kernel/security/lockdown.
+
+config LOCK_DOWN_KERNEL_FORCE_INTEGRITY
+	bool "Integrity"
+	help
+	 The kernel runs in integrity mode by default. Features that allow
+	 the kernel to be modified at runtime are disabled.
+
+config LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY
+	bool "Confidentiality"
+	help
+	 The kernel runs in confidentiality mode by default. Features that
+	 allow the kernel to be modified at runtime or that permit userland
+	 code to read confidential material held inside the kernel are
+	 disabled.
+
+endchoice
+
diff --git a/security/lockdown/Makefile b/security/lockdown/Makefile
new file mode 100644
index 000000000000..e3634b9017e7
--- /dev/null
+++ b/security/lockdown/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SECURITY_LOCKDOWN_LSM) += lockdown.o
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
new file mode 100644
index 000000000000..d30c4d254b5f
--- /dev/null
+++ b/security/lockdown/lockdown.c
@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Lock down the kernel
+ *
+ * Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/security.h>
+#include <linux/export.h>
+#include <linux/lsm_hooks.h>
+
+static enum lockdown_reason kernel_locked_down;
+
+static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
+	[LOCKDOWN_NONE] = "none",
+	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
+	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
+};
+
+static enum lockdown_reason lockdown_levels[] = {LOCKDOWN_NONE,
+						 LOCKDOWN_INTEGRITY_MAX,
+						 LOCKDOWN_CONFIDENTIALITY_MAX};
+
+/*
+ * Put the kernel into lock-down mode.
+ */
+static int lock_kernel_down(const char *where, enum lockdown_reason level)
+{
+	if (kernel_locked_down >= level)
+		return -EPERM;
+
+	kernel_locked_down = level;
+	pr_notice("Kernel is locked down from %s; see man kernel_lockdown.7\n",
+		  where);
+	return 0;
+}
+
+static int __init lockdown_param(char *level)
+{
+	if (!level)
+		return -EINVAL;
+
+	if (strcmp(level, "integrity") == 0)
+		lock_kernel_down("command line", LOCKDOWN_INTEGRITY_MAX);
+	else if (strcmp(level, "confidentiality") == 0)
+		lock_kernel_down("command line", LOCKDOWN_CONFIDENTIALITY_MAX);
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+early_param("lockdown", lockdown_param);
+
+/**
+ * lockdown_is_locked_down - Find out if the kernel is locked down
+ * @what: Tag to use in notice generated if lockdown is in effect
+ */
+static int lockdown_is_locked_down(enum lockdown_reason what)
+{
+	if (kernel_locked_down >= what) {
+		if (lockdown_reasons[what])
+			pr_notice("Lockdown: %s is restricted; see man kernel_lockdown.7\n",
+				  lockdown_reasons[what]);
+		return -EPERM;
+	}
+
+	return 0;
+}
+
+static struct security_hook_list lockdown_hooks[] __lsm_ro_after_init = {
+	LSM_HOOK_INIT(locked_down, lockdown_is_locked_down),
+};
+
+static int __init lockdown_lsm_init(void)
+{
+#if defined(CONFIG_LOCK_DOWN_KERNEL_FORCE_INTEGRITY)
+	lock_kernel_down("Kernel configuration", LOCKDOWN_INTEGRITY_MAX);
+#elif defined(CONFIG_LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY)
+	lock_kernel_down("Kernel configuration", LOCKDOWN_CONFIDENTIALITY_MAX);
+#endif
+	security_add_hooks(lockdown_hooks, ARRAY_SIZE(lockdown_hooks),
+			   "lockdown");
+	return 0;
+}
+
+static ssize_t lockdown_read(struct file *filp, char __user *buf, size_t count,
+			     loff_t *ppos)
+{
+	char temp[80];
+	int i, offset = 0;
+
+	for (i = 0; i < ARRAY_SIZE(lockdown_levels); i++) {
+		enum lockdown_reason level = lockdown_levels[i];
+
+		if (lockdown_reasons[level]) {
+			const char *label = lockdown_reasons[level];
+
+			if (kernel_locked_down == level)
+				offset += sprintf(temp+offset, "[%s] ", label);
+			else
+				offset += sprintf(temp+offset, "%s ", label);
+		}
+	}
+
+	/* Convert the last space to a newline if needed. */
+	if (offset > 0)
+		temp[offset-1] = '\n';
+
+	return simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
+}
+
+static ssize_t lockdown_write(struct file *file, const char __user *buf,
+			      size_t n, loff_t *ppos)
+{
+	char *state;
+	int i, len, err = -EINVAL;
+
+	state = memdup_user_nul(buf, n);
+	if (IS_ERR(state))
+		return PTR_ERR(state);
+
+	len = strlen(state);
+	if (len && state[len-1] == '\n') {
+		state[len-1] = '\0';
+		len--;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(lockdown_levels); i++) {
+		enum lockdown_reason level = lockdown_levels[i];
+		const char *label = lockdown_reasons[level];
+
+		if (label && !strcmp(state, label))
+			err = lock_kernel_down("securityfs", level);
+	}
+
+	kfree(state);
+	return err ? err : n;
+}
+
+static const struct file_operations lockdown_ops = {
+	.read  = lockdown_read,
+	.write = lockdown_write,
+};
+
+static int __init lockdown_secfs_init(void)
+{
+	struct dentry *dentry;
+
+	dentry = securityfs_create_file("lockdown", 0600, NULL, NULL,
+					&lockdown_ops);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+
+	return 0;
+}
+
+core_initcall(lockdown_secfs_init);
+
+#ifdef CONFIG_SECURITY_LOCKDOWN_LSM_EARLY
+DEFINE_EARLY_LSM(lockdown) = {
+#else
+DEFINE_LSM(lockdown) = {
+#endif
+	.name = "lockdown",
+	.init = lockdown_lsm_init,
+};
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 04/29] Enforce module signatures if the kernel is locked down

[Matthew Garrett]

From: David Howells <dhowells@redhat.com>

If the kernel is locked down, require that all modules have valid
signatures that we can verify.

I have adjusted the errors generated:

 (1) If there's no signature (ENODATA) or we can't check it (ENOPKG,
     ENOKEY), then:

     (a) If signatures are enforced then EKEYREJECTED is returned.

     (b) If there's no signature or we can't check it, but the kernel is
	 locked down then EPERM is returned (this is then consistent with
	 other lockdown cases).

 (2) If the signature is unparseable (EBADMSG, EINVAL), the signature fails
     the check (EKEYREJECTED) or a system error occurs (eg. ENOMEM), we
     return the error we got.

Note that the X.509 code doesn't check for key expiry as the RTC might not
be valid or might not have been transferred to the kernel's clock yet.

 [Modified by Matthew Garrett to remove the IMA integration. This will
  be replaced with integration with the IMA architecture policy
  patchset.]

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <matthewgarrett@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Jessica Yu <jeyu@kernel.org>
---
 include/linux/security.h     |  1 +
 kernel/module.c              | 37 +++++++++++++++++++++++++++++-------
 security/lockdown/lockdown.c |  1 +
 3 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index 54a0532ec12f..8e70063074a1 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -103,6 +103,7 @@ enum lsm_event {
  */
 enum lockdown_reason {
 	LOCKDOWN_NONE,
+	LOCKDOWN_MODULE_SIGNATURE,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/kernel/module.c b/kernel/module.c
index a2cee14a83f3..d8e1258e54af 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2753,8 +2753,9 @@ static inline void kmemleak_load_module(const struct module *mod,
 #ifdef CONFIG_MODULE_SIG
 static int module_sig_check(struct load_info *info, int flags)
 {
-	int err = -ENOKEY;
+	int err = -ENODATA;
 	const unsigned long markerlen = sizeof(MODULE_SIG_STRING) - 1;
+	const char *reason;
 	const void *mod = info->hdr;
 
 	/*
@@ -2769,16 +2770,38 @@ static int module_sig_check(struct load_info *info, int flags)
 		err = mod_verify_sig(mod, info);
 	}
 
-	if (!err) {
+	switch (err) {
+	case 0:
 		info->sig_ok = true;
 		return 0;
-	}
 
-	/* Not having a signature is only an error if we're strict. */
-	if (err == -ENOKEY && !is_module_sig_enforced())
-		err = 0;
+		/* We don't permit modules to be loaded into trusted kernels
+		 * without a valid signature on them, but if we're not
+		 * enforcing, certain errors are non-fatal.
+		 */
+	case -ENODATA:
+		reason = "Loading of unsigned module";
+		goto decide;
+	case -ENOPKG:
+		reason = "Loading of module with unsupported crypto";
+		goto decide;
+	case -ENOKEY:
+		reason = "Loading of module with unavailable key";
+	decide:
+		if (is_module_sig_enforced()) {
+			pr_notice("%s is rejected\n", reason);
+			return -EKEYREJECTED;
+		}
 
-	return err;
+		return security_locked_down(LOCKDOWN_MODULE_SIGNATURE);
+
+		/* All other errors are fatal, including nomem, unparseable
+		 * signatures and signature check failures - even if signatures
+		 * aren't required.
+		 */
+	default:
+		return err;
+	}
 }
 #else /* !CONFIG_MODULE_SIG */
 static int module_sig_check(struct load_info *info, int flags)
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index d30c4d254b5f..2c53fd9f5c9b 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -18,6 +18,7 @@ static enum lockdown_reason kernel_locked_down;
 
 static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_NONE] = "none",
+	[LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 05/29] Restrict /dev/{mem,kmem,port} when the kernel is locked down

[Matthew Garrett]

From: Matthew Garrett <mjg59@srcf.ucam.org>

Allowing users to read and write to core kernel memory makes it possible
for the kernel to be subverted, avoiding module loading restrictions, and
also to steal cryptographic information.

Disallow /dev/mem and /dev/kmem from being opened this when the kernel has
been locked down to prevent this.

Also disallow /dev/port from being opened to prevent raw ioport access and
thus DMA from being used to accomplish the same thing.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: x86@kernel.org
---
 drivers/char/mem.c           | 7 +++++--
 include/linux/security.h     | 1 +
 security/lockdown/lockdown.c | 1 +
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index b08dc50f9f26..d0148aee1aab 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -29,8 +29,8 @@
 #include <linux/export.h>
 #include <linux/io.h>
 #include <linux/uio.h>
-
 #include <linux/uaccess.h>
+#include <linux/security.h>
 
 #ifdef CONFIG_IA64
 # include <linux/efi.h>
@@ -786,7 +786,10 @@ static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
 
 static int open_port(struct inode *inode, struct file *filp)
 {
-	return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
+	if (!capable(CAP_SYS_RAWIO))
+		return -EPERM;
+
+	return security_locked_down(LOCKDOWN_DEV_MEM);
 }
 
 #define zero_lseek	null_lseek
diff --git a/include/linux/security.h b/include/linux/security.h
index 8e70063074a1..9458152601b5 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -104,6 +104,7 @@ enum lsm_event {
 enum lockdown_reason {
 	LOCKDOWN_NONE,
 	LOCKDOWN_MODULE_SIGNATURE,
+	LOCKDOWN_DEV_MEM,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 2c53fd9f5c9b..d2ef29d9f0b2 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -19,6 +19,7 @@ static enum lockdown_reason kernel_locked_down;
 static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_NONE] = "none",
 	[LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading",
+	[LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 06/29] kexec_load: Disable at runtime if the kernel is locked down

[Matthew Garrett]

From: Matthew Garrett <mjg59@srcf.ucam.org>

The kexec_load() syscall permits the loading and execution of arbitrary
code in ring 0, which is something that lock-down is meant to prevent. It
makes sense to disable kexec_load() in this situation.

This does not affect kexec_file_load() syscall which can check for a
signature on the image to be booted.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Dave Young <dyoung@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: kexec@lists.infradead.org
---
 include/linux/security.h     | 1 +
 kernel/kexec.c               | 8 ++++++++
 security/lockdown/lockdown.c | 1 +
 3 files changed, 10 insertions(+)

diff --git a/include/linux/security.h b/include/linux/security.h
index 9458152601b5..69c5de539e9a 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -105,6 +105,7 @@ enum lockdown_reason {
 	LOCKDOWN_NONE,
 	LOCKDOWN_MODULE_SIGNATURE,
 	LOCKDOWN_DEV_MEM,
+	LOCKDOWN_KEXEC,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 1b018f1a6e0d..bc933c0db9bf 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -205,6 +205,14 @@ static inline int kexec_load_check(unsigned long nr_segments,
 	if (result < 0)
 		return result;
 
+	/*
+	 * kexec can be used to circumvent module loading restrictions, so
+	 * prevent loading in that case
+	 */
+	result = security_locked_down(LOCKDOWN_KEXEC);
+	if (result)
+		return result;
+
 	/*
 	 * Verify we have a legal set of flags
 	 * This leaves us room for future extensions.
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index d2ef29d9f0b2..6f302c156bc8 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -20,6 +20,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_NONE] = "none",
 	[LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading",
 	[LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",
+	[LOCKDOWN_KEXEC] = "kexec of unsigned images",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 07/29] Copy secure_boot flag in boot params across kexec reboot

[Matthew Garrett]

From: Dave Young <dyoung@redhat.com>

Kexec reboot in case secure boot being enabled does not keep the secure
boot mode in new kernel, so later one can load unsigned kernel via legacy
kexec_load.  In this state, the system is missing the protections provided
by secure boot.

Adding a patch to fix this by retain the secure_boot flag in original
kernel.

secure_boot flag in boot_params is set in EFI stub, but kexec bypasses the
stub.  Fixing this issue by copying secure_boot flag across kexec reboot.

Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: kexec@lists.infradead.org
---
 arch/x86/kernel/kexec-bzimage64.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 5ebcd02cbca7..d2f4e706a428 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -180,6 +180,7 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
 	if (efi_enabled(EFI_OLD_MEMMAP))
 		return 0;
 
+	params->secure_boot = boot_params.secure_boot;
 	ei->efi_loader_signature = current_ei->efi_loader_signature;
 	ei->efi_systab = current_ei->efi_systab;
 	ei->efi_systab_hi = current_ei->efi_systab_hi;
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE

[Matthew Garrett]

From: Jiri Bohac <jbohac@suse.cz>

This is a preparatory patch for kexec_file_load() lockdown.  A locked down
kernel needs to prevent unsigned kernel images from being loaded with
kexec_file_load().  Currently, the only way to force the signature
verification is compiling with KEXEC_VERIFY_SIG.  This prevents loading
usigned images even when the kernel is not locked down at runtime.

This patch splits KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE.
Analogous to the MODULE_SIG and MODULE_SIG_FORCE for modules, KEXEC_SIG
turns on the signature verification but allows unsigned images to be
loaded.  KEXEC_SIG_FORCE disallows images without a valid signature.

Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Jiri Bohac <jbohac@suse.cz>
Reviewed-by: Dave Young <dyoung@redhat.com>
cc: kexec@lists.infradead.org
---
 arch/x86/Kconfig                       | 20 +++++++++----
 crypto/asymmetric_keys/verify_pefile.c |  4 ++-
 include/linux/kexec.h                  |  4 +--
 kernel/kexec_file.c                    | 41 ++++++++++++++++++++++----
 4 files changed, 55 insertions(+), 14 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9df2d1cb7a9e..104995fd32d0 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2026,20 +2026,30 @@ config KEXEC_FILE
 config ARCH_HAS_KEXEC_PURGATORY
 	def_bool KEXEC_FILE
 
-config KEXEC_VERIFY_SIG
+config KEXEC_SIG
 	bool "Verify kernel signature during kexec_file_load() syscall"
 	depends on KEXEC_FILE
 	---help---
-	  This option makes kernel signature verification mandatory for
-	  the kexec_file_load() syscall.
 
-	  In addition to that option, you need to enable signature
+	  This option makes the kexec_file_load() syscall check for a valid
+	  signature of the kernel image.  The image can still be loaded without
+	  a valid signature unless you also enable KEXEC_SIG_FORCE, though if
+	  there's a signature that we can check, then it must be valid.
+
+	  In addition to this option, you need to enable signature
 	  verification for the corresponding kernel image type being
 	  loaded in order for this to work.
 
+config KEXEC_SIG_FORCE
+	bool "Require a valid signature in kexec_file_load() syscall"
+	depends on KEXEC_SIG
+	---help---
+	  This option makes kernel signature verification mandatory for
+	  the kexec_file_load() syscall.
+
 config KEXEC_BZIMAGE_VERIFY_SIG
 	bool "Enable bzImage signature verification support"
-	depends on KEXEC_VERIFY_SIG
+	depends on KEXEC_SIG
 	depends on SIGNED_PE_FILE_VERIFICATION
 	select SYSTEM_TRUSTED_KEYRING
 	---help---
diff --git a/crypto/asymmetric_keys/verify_pefile.c b/crypto/asymmetric_keys/verify_pefile.c
index 3b303fe2f061..cc9dbcecaaca 100644
--- a/crypto/asymmetric_keys/verify_pefile.c
+++ b/crypto/asymmetric_keys/verify_pefile.c
@@ -96,7 +96,7 @@ static int pefile_parse_binary(const void *pebuf, unsigned int pelen,
 
 	if (!ddir->certs.virtual_address || !ddir->certs.size) {
 		pr_debug("Unsigned PE binary\n");
-		return -EKEYREJECTED;
+		return -ENODATA;
 	}
 
 	chkaddr(ctx->header_size, ddir->certs.virtual_address,
@@ -403,6 +403,8 @@ static int pefile_digest_pe(const void *pebuf, unsigned int pelen,
  *  (*) 0 if at least one signature chain intersects with the keys in the trust
  *	keyring, or:
  *
+ *  (*) -ENODATA if there is no signature present.
+ *
  *  (*) -ENOPKG if a suitable crypto module couldn't be found for a check on a
  *	chain.
  *
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index b9b1bc5f9669..58b27c7bdc2b 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -125,7 +125,7 @@ typedef void *(kexec_load_t)(struct kimage *image, char *kernel_buf,
 			     unsigned long cmdline_len);
 typedef int (kexec_cleanup_t)(void *loader_data);
 
-#ifdef CONFIG_KEXEC_VERIFY_SIG
+#ifdef CONFIG_KEXEC_SIG
 typedef int (kexec_verify_sig_t)(const char *kernel_buf,
 				 unsigned long kernel_len);
 #endif
@@ -134,7 +134,7 @@ struct kexec_file_ops {
 	kexec_probe_t *probe;
 	kexec_load_t *load;
 	kexec_cleanup_t *cleanup;
-#ifdef CONFIG_KEXEC_VERIFY_SIG
+#ifdef CONFIG_KEXEC_SIG
 	kexec_verify_sig_t *verify_sig;
 #endif
 };
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b8cc032d5620..875482c34154 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -88,7 +88,7 @@ int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
 	return kexec_image_post_load_cleanup_default(image);
 }
 
-#ifdef CONFIG_KEXEC_VERIFY_SIG
+#ifdef CONFIG_KEXEC_SIG
 static int kexec_image_verify_sig_default(struct kimage *image, void *buf,
 					  unsigned long buf_len)
 {
@@ -186,7 +186,8 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 			     const char __user *cmdline_ptr,
 			     unsigned long cmdline_len, unsigned flags)
 {
-	int ret = 0;
+	const char *reason;
+	int ret;
 	void *ldata;
 	loff_t size;
 
@@ -202,14 +203,42 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 	if (ret)
 		goto out;
 
-#ifdef CONFIG_KEXEC_VERIFY_SIG
+#ifdef CONFIG_KEXEC_SIG
 	ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
 					   image->kernel_buf_len);
-	if (ret) {
-		pr_debug("kernel signature verification failed.\n");
+	switch (ret) {
+	case 0:
+		break;
+
+		/* Certain verification errors are non-fatal if we're not
+		 * checking errors, provided we aren't mandating that there
+		 * must be a valid signature.
+		 */
+	case -ENODATA:
+		reason = "kexec of unsigned image";
+		goto decide;
+	case -ENOPKG:
+		reason = "kexec of image with unsupported crypto";
+		goto decide;
+	case -ENOKEY:
+		reason = "kexec of image with unavailable key";
+	decide:
+		if (IS_ENABLED(CONFIG_KEXEC_SIG_FORCE)) {
+			pr_notice("%s rejected\n", reason);
+			goto out;
+		}
+
+		ret = 0;
+		break;
+
+		/* All other errors are fatal, including nomem, unparseable
+		 * signatures and signature check failures - even if signatures
+		 * aren't required.
+		 */
+	default:
+		pr_notice("kernel signature verification failed (%d).\n", ret);
 		goto out;
 	}
-	pr_debug("kernel signature verification successful.\n");
 #endif
 	/* It is possible that there no initramfs is being loaded */
 	if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 09/29] kexec_file: Restrict at runtime if the kernel is locked down

[Matthew Garrett]

From: Jiri Bohac <jbohac@suse.cz>

When KEXEC_SIG is not enabled, kernel should not load images through
kexec_file systemcall if the kernel is locked down.

[Modified by David Howells to fit with modifications to the previous patch
 and to return -EPERM if the kernel is locked down for consistency with
 other lockdowns. Modified by Matthew Garrett to remove the IMA
 integration, which will be replaced by integrating with the IMA
 architecture policy patches.]

Signed-off-by: Jiri Bohac <jbohac@suse.cz>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Jiri Bohac <jbohac@suse.cz>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: kexec@lists.infradead.org
---
 kernel/kexec_file.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 875482c34154..dd06f1070d66 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -228,7 +228,10 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 			goto out;
 		}
 
-		ret = 0;
+		ret = security_locked_down(LOCKDOWN_KEXEC);
+		if (ret)
+			goto out;
+
 		break;
 
 		/* All other errors are fatal, including nomem, unparseable
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 10/29] hibernate: Disable when the kernel is locked down

[Matthew Garrett]

From: Josh Boyer <jwboyer@fedoraproject.org>

There is currently no way to verify the resume image when returning
from hibernate.  This might compromise the signed modules trust model,
so until we can work with signed hibernate images we disable it when the
kernel is locked down.

Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: rjw@rjwysocki.net
Cc: pavel@ucw.cz
cc: linux-pm@vger.kernel.org
---
 include/linux/security.h     | 1 +
 kernel/power/hibernate.c     | 3 ++-
 security/lockdown/lockdown.c | 1 +
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index 69c5de539e9a..304a155a5628 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -106,6 +106,7 @@ enum lockdown_reason {
 	LOCKDOWN_MODULE_SIGNATURE,
 	LOCKDOWN_DEV_MEM,
 	LOCKDOWN_KEXEC,
+	LOCKDOWN_HIBERNATION,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index cd7434e6000d..3c0a5a8170b0 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -30,6 +30,7 @@
 #include <linux/ctype.h>
 #include <linux/genhd.h>
 #include <linux/ktime.h>
+#include <linux/security.h>
 #include <trace/events/power.h>
 
 #include "power.h"
@@ -68,7 +69,7 @@ static const struct platform_hibernation_ops *hibernation_ops;
 
 bool hibernation_available(void)
 {
-	return (nohibernate == 0);
+	return nohibernate == 0 && !security_locked_down(LOCKDOWN_HIBERNATION);
 }
 
 /**
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 6f302c156bc8..a0996f75629f 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -21,6 +21,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading",
 	[LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",
 	[LOCKDOWN_KEXEC] = "kexec of unsigned images",
+	[LOCKDOWN_HIBERNATION] = "hibernation",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 11/29] PCI: Lock down BAR access when the kernel is locked down

[Matthew Garrett]

From: Matthew Garrett <mjg59@srcf.ucam.org>

Any hardware that can potentially generate DMA has to be locked down in
order to avoid it being possible for an attacker to modify kernel code,
allowing them to circumvent disabled module loading or module signing.
Default to paranoid - in future we can potentially relax this for
sufficiently IOMMU-isolated devices.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: linux-pci@vger.kernel.org
---
 drivers/pci/pci-sysfs.c      | 16 ++++++++++++++++
 drivers/pci/proc.c           | 14 ++++++++++++--
 drivers/pci/syscall.c        |  4 +++-
 include/linux/security.h     |  1 +
 security/lockdown/lockdown.c |  1 +
 5 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index 6d27475e39b2..ec103a7e13fc 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -903,6 +903,11 @@ static ssize_t pci_write_config(struct file *filp, struct kobject *kobj,
 	unsigned int size = count;
 	loff_t init_off = off;
 	u8 *data = (u8 *) buf;
+	int ret;
+
+	ret = security_locked_down(LOCKDOWN_PCI_ACCESS);
+	if (ret)
+		return ret;
 
 	if (off > dev->cfg_size)
 		return 0;
@@ -1164,6 +1169,11 @@ static int pci_mmap_resource(struct kobject *kobj, struct bin_attribute *attr,
 	int bar = (unsigned long)attr->private;
 	enum pci_mmap_state mmap_type;
 	struct resource *res = &pdev->resource[bar];
+	int ret;
+
+	ret = security_locked_down(LOCKDOWN_PCI_ACCESS);
+	if (ret)
+		return ret;
 
 	if (res->flags & IORESOURCE_MEM && iomem_is_exclusive(res->start))
 		return -EINVAL;
@@ -1240,6 +1250,12 @@ static ssize_t pci_write_resource_io(struct file *filp, struct kobject *kobj,
 				     struct bin_attribute *attr, char *buf,
 				     loff_t off, size_t count)
 {
+	int ret;
+
+	ret = security_locked_down(LOCKDOWN_PCI_ACCESS);
+	if (ret)
+		return ret;
+
 	return pci_resource_io(filp, kobj, attr, buf, off, count, true);
 }
 
diff --git a/drivers/pci/proc.c b/drivers/pci/proc.c
index 445b51db75b0..e29b0d5ced62 100644
--- a/drivers/pci/proc.c
+++ b/drivers/pci/proc.c
@@ -13,6 +13,7 @@
 #include <linux/seq_file.h>
 #include <linux/capability.h>
 #include <linux/uaccess.h>
+#include <linux/security.h>
 #include <asm/byteorder.h>
 #include "pci.h"
 
@@ -115,7 +116,11 @@ static ssize_t proc_bus_pci_write(struct file *file, const char __user *buf,
 	struct pci_dev *dev = PDE_DATA(ino);
 	int pos = *ppos;
 	int size = dev->cfg_size;
-	int cnt;
+	int cnt, ret;
+
+	ret = security_locked_down(LOCKDOWN_PCI_ACCESS);
+	if (ret)
+		return ret;
 
 	if (pos >= size)
 		return 0;
@@ -196,6 +201,10 @@ static long proc_bus_pci_ioctl(struct file *file, unsigned int cmd,
 #endif /* HAVE_PCI_MMAP */
 	int ret = 0;
 
+	ret = security_locked_down(LOCKDOWN_PCI_ACCESS);
+	if (ret)
+		return ret;
+
 	switch (cmd) {
 	case PCIIOC_CONTROLLER:
 		ret = pci_domain_nr(dev->bus);
@@ -238,7 +247,8 @@ static int proc_bus_pci_mmap(struct file *file, struct vm_area_struct *vma)
 	struct pci_filp_private *fpriv = file->private_data;
 	int i, ret, write_combine = 0, res_bit = IORESOURCE_MEM;
 
-	if (!capable(CAP_SYS_RAWIO))
+	if (!capable(CAP_SYS_RAWIO) ||
+	    security_locked_down(LOCKDOWN_PCI_ACCESS))
 		return -EPERM;
 
 	if (fpriv->mmap_state == pci_mmap_io) {
diff --git a/drivers/pci/syscall.c b/drivers/pci/syscall.c
index d96626c614f5..31e39558d49d 100644
--- a/drivers/pci/syscall.c
+++ b/drivers/pci/syscall.c
@@ -7,6 +7,7 @@
 
 #include <linux/errno.h>
 #include <linux/pci.h>
+#include <linux/security.h>
 #include <linux/syscalls.h>
 #include <linux/uaccess.h>
 #include "pci.h"
@@ -90,7 +91,8 @@ SYSCALL_DEFINE5(pciconfig_write, unsigned long, bus, unsigned long, dfn,
 	u32 dword;
 	int err = 0;
 
-	if (!capable(CAP_SYS_ADMIN))
+	if (!capable(CAP_SYS_ADMIN) ||
+	    security_locked_down(LOCKDOWN_PCI_ACCESS))
 		return -EPERM;
 
 	dev = pci_get_domain_bus_and_slot(0, bus, dfn);
diff --git a/include/linux/security.h b/include/linux/security.h
index 304a155a5628..8adbd62b7669 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -107,6 +107,7 @@ enum lockdown_reason {
 	LOCKDOWN_DEV_MEM,
 	LOCKDOWN_KEXEC,
 	LOCKDOWN_HIBERNATION,
+	LOCKDOWN_PCI_ACCESS,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index a0996f75629f..655fe388e615 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -22,6 +22,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",
 	[LOCKDOWN_KEXEC] = "kexec of unsigned images",
 	[LOCKDOWN_HIBERNATION] = "hibernation",
+	[LOCKDOWN_PCI_ACCESS] = "direct PCI access",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 12/29] x86: Lock down IO port access when the kernel is locked down

[Matthew Garrett]

From: Matthew Garrett <mjg59@srcf.ucam.org>

IO port access would permit users to gain access to PCI configuration
registers, which in turn (on a lot of hardware) give access to MMIO
register space. This would potentially permit root to trigger arbitrary
DMA, so lock it down by default.

This also implicitly locks down the KDADDIO, KDDELIO, KDENABIO and
KDDISABIO console ioctls.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: x86@kernel.org
---
 arch/x86/kernel/ioport.c     | 7 +++++--
 include/linux/security.h     | 1 +
 security/lockdown/lockdown.c | 1 +
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index 0fe1c8782208..61a89d3c0382 100644
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -11,6 +11,7 @@
 #include <linux/errno.h>
 #include <linux/types.h>
 #include <linux/ioport.h>
+#include <linux/security.h>
 #include <linux/smp.h>
 #include <linux/stddef.h>
 #include <linux/slab.h>
@@ -31,7 +32,8 @@ long ksys_ioperm(unsigned long from, unsigned long num, int turn_on)
 
 	if ((from + num <= from) || (from + num > IO_BITMAP_BITS))
 		return -EINVAL;
-	if (turn_on && !capable(CAP_SYS_RAWIO))
+	if (turn_on && (!capable(CAP_SYS_RAWIO) ||
+			security_locked_down(LOCKDOWN_IOPORT)))
 		return -EPERM;
 
 	/*
@@ -126,7 +128,8 @@ SYSCALL_DEFINE1(iopl, unsigned int, level)
 		return -EINVAL;
 	/* Trying to gain more privileges? */
 	if (level > old) {
-		if (!capable(CAP_SYS_RAWIO))
+		if (!capable(CAP_SYS_RAWIO) ||
+		    security_locked_down(LOCKDOWN_IOPORT))
 			return -EPERM;
 	}
 	regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) |
diff --git a/include/linux/security.h b/include/linux/security.h
index 8adbd62b7669..79250b2ffb8f 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -108,6 +108,7 @@ enum lockdown_reason {
 	LOCKDOWN_KEXEC,
 	LOCKDOWN_HIBERNATION,
 	LOCKDOWN_PCI_ACCESS,
+	LOCKDOWN_IOPORT,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 655fe388e615..316f7cf4e996 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -23,6 +23,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_KEXEC] = "kexec of unsigned images",
 	[LOCKDOWN_HIBERNATION] = "hibernation",
 	[LOCKDOWN_PCI_ACCESS] = "direct PCI access",
+	[LOCKDOWN_IOPORT] = "raw io port access",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 13/29] x86/msr: Restrict MSR access when the kernel is locked down

[Matthew Garrett]

From: Matthew Garrett <mjg59@srcf.ucam.org>

Writing to MSRs should not be allowed if the kernel is locked down, since
it could lead to execution of arbitrary code in kernel mode.  Based on a
patch by Kees Cook.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
cc: x86@kernel.org
---
 arch/x86/kernel/msr.c        | 8 ++++++++
 include/linux/security.h     | 1 +
 security/lockdown/lockdown.c | 1 +
 3 files changed, 10 insertions(+)

diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index 3db2252b958d..1547be359d7f 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -34,6 +34,7 @@
 #include <linux/notifier.h>
 #include <linux/uaccess.h>
 #include <linux/gfp.h>
+#include <linux/security.h>
 
 #include <asm/cpufeature.h>
 #include <asm/msr.h>
@@ -79,6 +80,10 @@ static ssize_t msr_write(struct file *file, const char __user *buf,
 	int err = 0;
 	ssize_t bytes = 0;
 
+	err = security_locked_down(LOCKDOWN_MSR);
+	if (err)
+		return err;
+
 	if (count % 8)
 		return -EINVAL;	/* Invalid chunk size */
 
@@ -130,6 +135,9 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg)
 			err = -EFAULT;
 			break;
 		}
+		err = security_locked_down(LOCKDOWN_MSR);
+		if (err)
+			break;
 		err = wrmsr_safe_regs_on_cpu(cpu, regs);
 		if (err)
 			break;
diff --git a/include/linux/security.h b/include/linux/security.h
index 79250b2ffb8f..155ff026eca4 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -109,6 +109,7 @@ enum lockdown_reason {
 	LOCKDOWN_HIBERNATION,
 	LOCKDOWN_PCI_ACCESS,
 	LOCKDOWN_IOPORT,
+	LOCKDOWN_MSR,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 316f7cf4e996..d99c0bee739d 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -24,6 +24,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_HIBERNATION] = "hibernation",
 	[LOCKDOWN_PCI_ACCESS] = "direct PCI access",
 	[LOCKDOWN_IOPORT] = "raw io port access",
+	[LOCKDOWN_MSR] = "raw MSR access",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 14/29] ACPI: Limit access to custom_method when the kernel is locked down

[Matthew Garrett]

From: Matthew Garrett <mjg59@srcf.ucam.org>

custom_method effectively allows arbitrary access to system memory, making
it possible for an attacker to circumvent restrictions on module loading.
Disable it if the kernel is locked down.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: linux-acpi@vger.kernel.org
---
 drivers/acpi/custom_method.c | 6 ++++++
 include/linux/security.h     | 1 +
 security/lockdown/lockdown.c | 1 +
 3 files changed, 8 insertions(+)

diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c
index b2ef4c2ec955..7031307becd7 100644
--- a/drivers/acpi/custom_method.c
+++ b/drivers/acpi/custom_method.c
@@ -9,6 +9,7 @@
 #include <linux/uaccess.h>
 #include <linux/debugfs.h>
 #include <linux/acpi.h>
+#include <linux/security.h>
 
 #include "internal.h"
 
@@ -29,6 +30,11 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf,
 
 	struct acpi_table_header table;
 	acpi_status status;
+	int ret;
+
+	ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
+	if (ret)
+		return ret;
 
 	if (!(*ppos)) {
 		/* parse the table header to get the table length */
diff --git a/include/linux/security.h b/include/linux/security.h
index 155ff026eca4..1c32522b3c5a 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -110,6 +110,7 @@ enum lockdown_reason {
 	LOCKDOWN_PCI_ACCESS,
 	LOCKDOWN_IOPORT,
 	LOCKDOWN_MSR,
+	LOCKDOWN_ACPI_TABLES,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index d99c0bee739d..67dbc5c70ea0 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -25,6 +25,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_PCI_ACCESS] = "direct PCI access",
 	[LOCKDOWN_IOPORT] = "raw io port access",
 	[LOCKDOWN_MSR] = "raw MSR access",
+	[LOCKDOWN_ACPI_TABLES] = "modified ACPI tables",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down

[Matthew Garrett]

From: Josh Boyer <jwboyer@redhat.com>

This option allows userspace to pass the RSDP address to the kernel, which
makes it possible for a user to modify the workings of hardware .  Reject
the option when the kernel is locked down.

Signed-off-by: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: Dave Young <dyoung@redhat.com>
cc: linux-acpi@vger.kernel.org
---
 drivers/acpi/osl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 9c0edf2fc0dd..06e7cffc4386 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -26,6 +26,7 @@
 #include <linux/list.h>
 #include <linux/jiffies.h>
 #include <linux/semaphore.h>
+#include <linux/security.h>
 
 #include <asm/io.h>
 #include <linux/uaccess.h>
@@ -180,7 +181,7 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
 	acpi_physical_address pa;
 
 #ifdef CONFIG_KEXEC
-	if (acpi_rsdp)
+	if (acpi_rsdp && !security_locked_down(LOCKDOWN_ACPI_TABLES))
 		return acpi_rsdp;
 #endif
 	pa = acpi_arch_get_root_pointer();
-- 
2.22.0.510.g264f2c817a-goog

Re: [PATCH V35 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down

[Dave Young]

Hi,
On 07/15/19 at 12:59pm, Matthew Garrett wrote:
> From: Josh Boyer <jwboyer@redhat.com>
> 
> This option allows userspace to pass the RSDP address to the kernel, which
> makes it possible for a user to modify the workings of hardware .  Reject
> the option when the kernel is locked down.
> 
> Signed-off-by: Josh Boyer <jwboyer@redhat.com>
> Signed-off-by: David Howells <dhowells@redhat.com>
> Signed-off-by: Matthew Garrett <mjg59@google.com>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> cc: Dave Young <dyoung@redhat.com>
> cc: linux-acpi@vger.kernel.org
> ---
>  drivers/acpi/osl.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
> index 9c0edf2fc0dd..06e7cffc4386 100644
> --- a/drivers/acpi/osl.c
> +++ b/drivers/acpi/osl.c
> @@ -26,6 +26,7 @@
>  #include <linux/list.h>
>  #include <linux/jiffies.h>
>  #include <linux/semaphore.h>
> +#include <linux/security.h>
>  
>  #include <asm/io.h>
>  #include <linux/uaccess.h>
> @@ -180,7 +181,7 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
>  	acpi_physical_address pa;
>  
>  #ifdef CONFIG_KEXEC
> -	if (acpi_rsdp)
> +	if (acpi_rsdp && !security_locked_down(LOCKDOWN_ACPI_TABLES))
>  		return acpi_rsdp;

I'm very sorry I noticed this late, but have to say this will not work for
X86 with latest kernel code.

acpi_physical_address __init acpi_os_get_root_pointer(void)
{
        acpi_physical_address pa;

#ifdef CONFIG_KEXEC
        if (acpi_rsdp)
                return acpi_rsdp;
#endif
        pa = acpi_arch_get_root_pointer();
        if (pa)
                return pa;
[snip]

In above code, the later acpi_arch_get_root_pointer still get acpi_rsdp
from cmdline param if provided.

You can check the arch/x86/boot/compressed/acpi.c, and
arch/x86/kernel/acpi/boot.c

In X86 early code, cmdline provided acpi_rsdp pointer will be saved in boot_params.acpi_rsdp_addr;
and the used in x86_default_get_root_pointer
 
>  #endif
>  	pa = acpi_arch_get_root_pointer();
> -- 
> 2.22.0.510.g264f2c817a-goog
> 

Thanks
Dave

Re: [PATCH V35 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down

[Matthew Garrett]

On Mon, Jul 15, 2019 at 7:59 PM Dave Young <dyoung@redhat.com> wrote:
> I'm very sorry I noticed this late, but have to say this will not work for
> X86 with latest kernel code.

No problem, thank you for catching this! I'll update the patch and
send a new version.

[PATCH V35 16/29] acpi: Disable ACPI table override if the kernel is locked down

[Matthew Garrett]

From: Linn Crosetto <linn@hpe.com>

From the kernel documentation (initrd_table_override.txt):

  If the ACPI_INITRD_TABLE_OVERRIDE compile option is true, it is possible
  to override nearly any ACPI table provided by the BIOS with an
  instrumented, modified one.

When lockdown is enabled, the kernel should disallow any unauthenticated
changes to kernel space.  ACPI tables contain code invoked by the kernel,
so do not allow ACPI tables to be overridden if the kernel is locked down.

Signed-off-by: Linn Crosetto <linn@hpe.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: linux-acpi@vger.kernel.org
---
 drivers/acpi/tables.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index b32327759380..180ac4329763 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -20,6 +20,7 @@
 #include <linux/memblock.h>
 #include <linux/earlycpio.h>
 #include <linux/initrd.h>
+#include <linux/security.h>
 #include "internal.h"
 
 #ifdef CONFIG_ACPI_CUSTOM_DSDT
@@ -578,6 +579,11 @@ void __init acpi_table_upgrade(void)
 	if (table_nr == 0)
 		return;
 
+	if (security_locked_down(LOCKDOWN_ACPI_TABLES)) {
+		pr_notice("kernel is locked down, ignoring table override\n");
+		return;
+	}
+
 	acpi_tables_addr =
 		memblock_find_in_range(0, ACPI_TABLE_UPGRADE_MAX_PHYS,
 				       all_tables_size, PAGE_SIZE);
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 17/29] Prohibit PCMCIA CIS storage when the kernel is locked down

[Matthew Garrett]

From: David Howells <dhowells@redhat.com>

Prohibit replacement of the PCMCIA Card Information Structure when the
kernel is locked down.

Suggested-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
 drivers/pcmcia/cistpl.c      | 5 +++++
 include/linux/security.h     | 1 +
 security/lockdown/lockdown.c | 1 +
 3 files changed, 7 insertions(+)

diff --git a/drivers/pcmcia/cistpl.c b/drivers/pcmcia/cistpl.c
index abd029945cc8..629359fe3513 100644
--- a/drivers/pcmcia/cistpl.c
+++ b/drivers/pcmcia/cistpl.c
@@ -21,6 +21,7 @@
 #include <linux/pci.h>
 #include <linux/ioport.h>
 #include <linux/io.h>
+#include <linux/security.h>
 #include <asm/byteorder.h>
 #include <asm/unaligned.h>
 
@@ -1575,6 +1576,10 @@ static ssize_t pccard_store_cis(struct file *filp, struct kobject *kobj,
 	struct pcmcia_socket *s;
 	int error;
 
+	error = security_locked_down(LOCKDOWN_PCMCIA_CIS);
+	if (error)
+		return error;
+
 	s = to_socket(container_of(kobj, struct device, kobj));
 
 	if (off)
diff --git a/include/linux/security.h b/include/linux/security.h
index 1c32522b3c5a..3773ad09b831 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -111,6 +111,7 @@ enum lockdown_reason {
 	LOCKDOWN_IOPORT,
 	LOCKDOWN_MSR,
 	LOCKDOWN_ACPI_TABLES,
+	LOCKDOWN_PCMCIA_CIS,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 67dbc5c70ea0..96106c2870ef 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -26,6 +26,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_IOPORT] = "raw io port access",
 	[LOCKDOWN_MSR] = "raw MSR access",
 	[LOCKDOWN_ACPI_TABLES] = "modified ACPI tables",
+	[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 18/29] Lock down TIOCSSERIAL

[Matthew Garrett]

From: David Howells <dhowells@redhat.com>

Lock down TIOCSSERIAL as that can be used to change the ioport and irq
settings on a serial port.  This only appears to be an issue for the serial
drivers that use the core serial code.  All other drivers seem to either
ignore attempts to change port/irq or give an error.

Reported-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-serial@vger.kernel.org
---
 drivers/tty/serial/serial_core.c | 5 +++++
 include/linux/security.h         | 1 +
 security/lockdown/lockdown.c     | 1 +
 3 files changed, 7 insertions(+)

diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 4223cb496764..6e713be1d4e9 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -22,6 +22,7 @@
 #include <linux/serial_core.h>
 #include <linux/delay.h>
 #include <linux/mutex.h>
+#include <linux/security.h>
 
 #include <linux/irq.h>
 #include <linux/uaccess.h>
@@ -862,6 +863,10 @@ static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
 		goto check_and_exit;
 	}
 
+	retval = security_locked_down(LOCKDOWN_TIOCSSERIAL);
+	if (retval && (change_irq || change_port))
+		goto exit;
+
 	/*
 	 * Ask the low level driver to verify the settings.
 	 */
diff --git a/include/linux/security.h b/include/linux/security.h
index 3773ad09b831..8f7048395114 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -112,6 +112,7 @@ enum lockdown_reason {
 	LOCKDOWN_MSR,
 	LOCKDOWN_ACPI_TABLES,
 	LOCKDOWN_PCMCIA_CIS,
+	LOCKDOWN_TIOCSSERIAL,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 96106c2870ef..07a49667f234 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -27,6 +27,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_MSR] = "raw MSR access",
 	[LOCKDOWN_ACPI_TABLES] = "modified ACPI tables",
 	[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
+	[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 19/29] Lock down module params that specify hardware parameters (eg. ioport)

[Matthew Garrett]

From: David Howells <dhowells@redhat.com>

Provided an annotation for module parameters that specify hardware
parameters (such as io ports, iomem addresses, irqs, dma channels, fixed
dma buffers and other types).

Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
 include/linux/security.h     |  1 +
 kernel/params.c              | 28 +++++++++++++++++++++++-----
 security/lockdown/lockdown.c |  1 +
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index 8f7048395114..43fa3486522b 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -113,6 +113,7 @@ enum lockdown_reason {
 	LOCKDOWN_ACPI_TABLES,
 	LOCKDOWN_PCMCIA_CIS,
 	LOCKDOWN_TIOCSSERIAL,
+	LOCKDOWN_MODULE_PARAMETERS,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/kernel/params.c b/kernel/params.c
index cf448785d058..f2779a76d39a 100644
--- a/kernel/params.c
+++ b/kernel/params.c
@@ -12,6 +12,7 @@
 #include <linux/err.h>
 #include <linux/slab.h>
 #include <linux/ctype.h>
+#include <linux/security.h>
 
 #ifdef CONFIG_SYSFS
 /* Protects all built-in parameters, modules use their own param_lock */
@@ -96,13 +97,20 @@ bool parameq(const char *a, const char *b)
 	return parameqn(a, b, strlen(a)+1);
 }
 
-static void param_check_unsafe(const struct kernel_param *kp)
+static bool param_check_unsafe(const struct kernel_param *kp,
+			       const char *doing)
 {
+	if (kp->flags & KERNEL_PARAM_FL_HWPARAM &&
+	    security_locked_down(LOCKDOWN_MODULE_PARAMETERS))
+		return false;
+
 	if (kp->flags & KERNEL_PARAM_FL_UNSAFE) {
 		pr_notice("Setting dangerous option %s - tainting kernel\n",
 			  kp->name);
 		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
 	}
+
+	return true;
 }
 
 static int parse_one(char *param,
@@ -132,8 +140,10 @@ static int parse_one(char *param,
 			pr_debug("handling %s with %p\n", param,
 				params[i].ops->set);
 			kernel_param_lock(params[i].mod);
-			param_check_unsafe(&params[i]);
-			err = params[i].ops->set(val, &params[i]);
+			if (param_check_unsafe(&params[i], doing))
+				err = params[i].ops->set(val, &params[i]);
+			else
+				err = -EPERM;
 			kernel_param_unlock(params[i].mod);
 			return err;
 		}
@@ -541,6 +551,12 @@ static ssize_t param_attr_show(struct module_attribute *mattr,
 	return count;
 }
 
+#ifdef CONFIG_MODULES
+#define mod_name(mod) ((mod)->name)
+#else
+#define mod_name(mod) "unknown"
+#endif
+
 /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
 static ssize_t param_attr_store(struct module_attribute *mattr,
 				struct module_kobject *mk,
@@ -553,8 +569,10 @@ static ssize_t param_attr_store(struct module_attribute *mattr,
 		return -EPERM;
 
 	kernel_param_lock(mk->mod);
-	param_check_unsafe(attribute->param);
-	err = attribute->param->ops->set(buf, attribute->param);
+	if (param_check_unsafe(attribute->param, mod_name(mk->mod)))
+		err = attribute->param->ops->set(buf, attribute->param);
+	else
+		err = -EPERM;
 	kernel_param_unlock(mk->mod);
 	if (!err)
 		return len;
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 07a49667f234..065432f9e218 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -28,6 +28,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_ACPI_TABLES] = "modified ACPI tables",
 	[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
 	[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
+	[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.510.g264f2c817a-goog

Re: [PATCH V35 19/29] Lock down module params that specify hardware parameters (eg. ioport)

[James Morris]

On Mon, 15 Jul 2019, Matthew Garrett wrote:

> From: David Howells <dhowells@redhat.com>
> 
> Provided an annotation for module parameters that specify hardware
> parameters (such as io ports, iomem addresses, irqs, dma channels, fixed
> dma buffers and other types).

Adding Jessica.

> 
> Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
> Signed-off-by: David Howells <dhowells@redhat.com>
> Signed-off-by: Matthew Garrett <mjg59@google.com>
> Reviewed-by: Kees Cook <keescook@chromium.org>
> ---
>  include/linux/security.h     |  1 +
>  kernel/params.c              | 28 +++++++++++++++++++++++-----
>  security/lockdown/lockdown.c |  1 +
>  3 files changed, 25 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 8f7048395114..43fa3486522b 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -113,6 +113,7 @@ enum lockdown_reason {
>  	LOCKDOWN_ACPI_TABLES,
>  	LOCKDOWN_PCMCIA_CIS,
>  	LOCKDOWN_TIOCSSERIAL,
> +	LOCKDOWN_MODULE_PARAMETERS,
>  	LOCKDOWN_INTEGRITY_MAX,
>  	LOCKDOWN_CONFIDENTIALITY_MAX,
>  };
> diff --git a/kernel/params.c b/kernel/params.c
> index cf448785d058..f2779a76d39a 100644
> --- a/kernel/params.c
> +++ b/kernel/params.c
> @@ -12,6 +12,7 @@
>  #include <linux/err.h>
>  #include <linux/slab.h>
>  #include <linux/ctype.h>
> +#include <linux/security.h>
>  
>  #ifdef CONFIG_SYSFS
>  /* Protects all built-in parameters, modules use their own param_lock */
> @@ -96,13 +97,20 @@ bool parameq(const char *a, const char *b)
>  	return parameqn(a, b, strlen(a)+1);
>  }
>  
> -static void param_check_unsafe(const struct kernel_param *kp)
> +static bool param_check_unsafe(const struct kernel_param *kp,
> +			       const char *doing)
>  {
> +	if (kp->flags & KERNEL_PARAM_FL_HWPARAM &&
> +	    security_locked_down(LOCKDOWN_MODULE_PARAMETERS))
> +		return false;
> +
>  	if (kp->flags & KERNEL_PARAM_FL_UNSAFE) {
>  		pr_notice("Setting dangerous option %s - tainting kernel\n",
>  			  kp->name);
>  		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
>  	}
> +
> +	return true;
>  }
>  
>  static int parse_one(char *param,
> @@ -132,8 +140,10 @@ static int parse_one(char *param,
>  			pr_debug("handling %s with %p\n", param,
>  				params[i].ops->set);
>  			kernel_param_lock(params[i].mod);
> -			param_check_unsafe(&params[i]);
> -			err = params[i].ops->set(val, &params[i]);
> +			if (param_check_unsafe(&params[i], doing))
> +				err = params[i].ops->set(val, &params[i]);
> +			else
> +				err = -EPERM;
>  			kernel_param_unlock(params[i].mod);
>  			return err;
>  		}
> @@ -541,6 +551,12 @@ static ssize_t param_attr_show(struct module_attribute *mattr,
>  	return count;
>  }
>  
> +#ifdef CONFIG_MODULES
> +#define mod_name(mod) ((mod)->name)
> +#else
> +#define mod_name(mod) "unknown"
> +#endif
> +
>  /* sysfs always hands a nul-terminated string in buf.  We rely on that. */
>  static ssize_t param_attr_store(struct module_attribute *mattr,
>  				struct module_kobject *mk,
> @@ -553,8 +569,10 @@ static ssize_t param_attr_store(struct module_attribute *mattr,
>  		return -EPERM;
>  
>  	kernel_param_lock(mk->mod);
> -	param_check_unsafe(attribute->param);
> -	err = attribute->param->ops->set(buf, attribute->param);
> +	if (param_check_unsafe(attribute->param, mod_name(mk->mod)))
> +		err = attribute->param->ops->set(buf, attribute->param);
> +	else
> +		err = -EPERM;
>  	kernel_param_unlock(mk->mod);
>  	if (!err)
>  		return len;
> diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
> index 07a49667f234..065432f9e218 100644
> --- a/security/lockdown/lockdown.c
> +++ b/security/lockdown/lockdown.c
> @@ -28,6 +28,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
>  	[LOCKDOWN_ACPI_TABLES] = "modified ACPI tables",
>  	[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
>  	[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
> +	[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
>  	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
>  	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
>  };
> 

-- 
James Morris
<jmorris@namei.org>

[PATCH V35 20/29] x86/mmiotrace: Lock down the testmmiotrace module

[Matthew Garrett]

From: David Howells <dhowells@redhat.com>

The testmmiotrace module shouldn't be permitted when the kernel is locked
down as it can be used to arbitrarily read and write MMIO space. This is
a runtime check rather than buildtime in order to allow configurations
where the same kernel may be run in both locked down or permissive modes
depending on local policy.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: David Howells <dhowells@redhat.com
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
cc: Thomas Gleixner <tglx@linutronix.de>
cc: Steven Rostedt <rostedt@goodmis.org>
cc: Ingo Molnar <mingo@kernel.org>
cc: "H. Peter Anvin" <hpa@zytor.com>
cc: x86@kernel.org
---
 arch/x86/mm/testmmiotrace.c  | 5 +++++
 include/linux/security.h     | 1 +
 security/lockdown/lockdown.c | 1 +
 3 files changed, 7 insertions(+)

diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c
index 0881e1ff1e58..a8bd952e136d 100644
--- a/arch/x86/mm/testmmiotrace.c
+++ b/arch/x86/mm/testmmiotrace.c
@@ -8,6 +8,7 @@
 #include <linux/module.h>
 #include <linux/io.h>
 #include <linux/mmiotrace.h>
+#include <linux/security.h>
 
 static unsigned long mmio_address;
 module_param_hw(mmio_address, ulong, iomem, 0);
@@ -115,6 +116,10 @@ static void do_test_bulk_ioremapping(void)
 static int __init init(void)
 {
 	unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
+	int ret = security_locked_down(LOCKDOWN_MMIOTRACE);
+
+	if (ret)
+		return ret;
 
 	if (mmio_address == 0) {
 		pr_err("you have to use the module argument mmio_address.\n");
diff --git a/include/linux/security.h b/include/linux/security.h
index 43fa3486522b..3f7b6a4cd65a 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -114,6 +114,7 @@ enum lockdown_reason {
 	LOCKDOWN_PCMCIA_CIS,
 	LOCKDOWN_TIOCSSERIAL,
 	LOCKDOWN_MODULE_PARAMETERS,
+	LOCKDOWN_MMIOTRACE,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 065432f9e218..e725f63c29d2 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -29,6 +29,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
 	[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
 	[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
+	[LOCKDOWN_MMIOTRACE] = "unsafe mmio",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 21/29] Lock down /proc/kcore

[Matthew Garrett]

From: David Howells <dhowells@redhat.com>

Disallow access to /proc/kcore when the kernel is locked down to prevent
access to cryptographic data. This is limited to lockdown
confidentiality mode and is still permitted in integrity mode.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
 fs/proc/kcore.c              | 5 +++++
 include/linux/security.h     | 1 +
 security/lockdown/lockdown.c | 1 +
 3 files changed, 7 insertions(+)

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index f5834488b67d..ee2c576cc94e 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -31,6 +31,7 @@
 #include <linux/ioport.h>
 #include <linux/memory.h>
 #include <linux/sched/task.h>
+#include <linux/security.h>
 #include <asm/sections.h>
 #include "internal.h"
 
@@ -545,6 +546,10 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 
 static int open_kcore(struct inode *inode, struct file *filp)
 {
+	int ret = security_locked_down(LOCKDOWN_KCORE);
+
+	if (ret)
+		return ret;
 	if (!capable(CAP_SYS_RAWIO))
 		return -EPERM;
 
diff --git a/include/linux/security.h b/include/linux/security.h
index 3f7b6a4cd65a..f0cffd0977d3 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -116,6 +116,7 @@ enum lockdown_reason {
 	LOCKDOWN_MODULE_PARAMETERS,
 	LOCKDOWN_MMIOTRACE,
 	LOCKDOWN_INTEGRITY_MAX,
+	LOCKDOWN_KCORE,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
 
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index e725f63c29d2..9c097240a3a6 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -31,6 +31,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
 	[LOCKDOWN_MMIOTRACE] = "unsafe mmio",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
+	[LOCKDOWN_KCORE] = "/proc/kcore access",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
 
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 22/29] Lock down tracing and perf kprobes when in confidentiality mode

[Matthew Garrett]

From: David Howells <dhowells@redhat.com>

Disallow the creation of perf and ftrace kprobes when the kernel is
locked down in confidentiality mode by preventing their registration.
This prevents kprobes from being used to access kernel memory to steal
crypto data, but continues to allow the use of kprobes from signed
modules.

Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: davem@davemloft.net
Cc: Masami Hiramatsu <mhiramat@kernel.org>
---
 include/linux/security.h     | 1 +
 kernel/trace/trace_kprobe.c  | 5 +++++
 security/lockdown/lockdown.c | 1 +
 3 files changed, 7 insertions(+)

diff --git a/include/linux/security.h b/include/linux/security.h
index f0cffd0977d3..987d8427f091 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -117,6 +117,7 @@ enum lockdown_reason {
 	LOCKDOWN_MMIOTRACE,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_KCORE,
+	LOCKDOWN_KPROBES,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
 
diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index 7d736248a070..fcb28b0702b2 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -11,6 +11,7 @@
 #include <linux/uaccess.h>
 #include <linux/rculist.h>
 #include <linux/error-injection.h>
+#include <linux/security.h>
 
 #include "trace_dynevent.h"
 #include "trace_kprobe_selftest.h"
@@ -415,6 +416,10 @@ static int __register_trace_kprobe(struct trace_kprobe *tk)
 {
 	int i, ret;
 
+	ret = security_locked_down(LOCKDOWN_KPROBES);
+	if (ret)
+		return ret;
+
 	if (trace_probe_is_registered(&tk->tp))
 		return -EINVAL;
 
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 9c097240a3a6..ccb3e9a2a47c 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -32,6 +32,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_MMIOTRACE] = "unsafe mmio",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_KCORE] = "/proc/kcore access",
+	[LOCKDOWN_KPROBES] = "use of kprobes",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
 
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 23/29] bpf: Restrict bpf when kernel lockdown is in confidentiality mode

[Matthew Garrett]

From: David Howells <dhowells@redhat.com>

bpf_read() and bpf_read_str() could potentially be abused to (eg) allow
private keys in kernel memory to be leaked. Disable them if the kernel
has been locked down in confidentiality mode.

Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
cc: netdev@vger.kernel.org
cc: Chun-Yi Lee <jlee@suse.com>
cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
---
 include/linux/security.h     |  1 +
 kernel/trace/bpf_trace.c     | 10 ++++++++++
 security/lockdown/lockdown.c |  1 +
 3 files changed, 12 insertions(+)

diff --git a/include/linux/security.h b/include/linux/security.h
index 987d8427f091..8dd1741a52cd 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -118,6 +118,7 @@ enum lockdown_reason {
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_KCORE,
 	LOCKDOWN_KPROBES,
+	LOCKDOWN_BPF_READ,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
 
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index ca1255d14576..605908da61c5 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -142,7 +142,12 @@ BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr)
 {
 	int ret;
 
+	ret = security_locked_down(LOCKDOWN_BPF_READ);
+	if (ret)
+		goto out;
+
 	ret = probe_kernel_read(dst, unsafe_ptr, size);
+out:
 	if (unlikely(ret < 0))
 		memset(dst, 0, size);
 
@@ -569,6 +574,10 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
 {
 	int ret;
 
+	ret = security_locked_down(LOCKDOWN_BPF_READ);
+	if (ret)
+		goto out;
+
 	/*
 	 * The strncpy_from_unsafe() call will likely not fill the entire
 	 * buffer, but that's okay in this circumstance as we're probing
@@ -579,6 +588,7 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
 	 * is returned that can be used for bpf_perf_event_output() et al.
 	 */
 	ret = strncpy_from_unsafe(dst, unsafe_ptr, size);
+out:
 	if (unlikely(ret < 0))
 		memset(dst, 0, size);
 
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index ccb3e9a2a47c..d14b89784412 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -33,6 +33,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_KCORE] = "/proc/kcore access",
 	[LOCKDOWN_KPROBES] = "use of kprobes",
+	[LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
 
-- 
2.22.0.510.g264f2c817a-goog

Re: [PATCH V35 23/29] bpf: Restrict bpf when kernel lockdown is in confidentiality mode

[Daniel Borkmann]

On 7/15/19 9:59 PM, Matthew Garrett wrote:
> From: David Howells <dhowells@redhat.com>
> 
> bpf_read() and bpf_read_str() could potentially be abused to (eg) allow
> private keys in kernel memory to be leaked. Disable them if the kernel
> has been locked down in confidentiality mode.
> 
> Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
> Signed-off-by: Matthew Garrett <mjg59@google.com>
> cc: netdev@vger.kernel.org
> cc: Chun-Yi Lee <jlee@suse.com>
> cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> ---
>  include/linux/security.h     |  1 +
>  kernel/trace/bpf_trace.c     | 10 ++++++++++
>  security/lockdown/lockdown.c |  1 +
>  3 files changed, 12 insertions(+)
> 
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 987d8427f091..8dd1741a52cd 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -118,6 +118,7 @@ enum lockdown_reason {
>  	LOCKDOWN_INTEGRITY_MAX,
>  	LOCKDOWN_KCORE,
>  	LOCKDOWN_KPROBES,
> +	LOCKDOWN_BPF_READ,
>  	LOCKDOWN_CONFIDENTIALITY_MAX,
>  };
>  
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index ca1255d14576..605908da61c5 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -142,7 +142,12 @@ BPF_CALL_3(bpf_probe_read, void *, dst, u32, size, const void *, unsafe_ptr)
>  {
>  	int ret;
>  
> +	ret = security_locked_down(LOCKDOWN_BPF_READ);
> +	if (ret)
> +		goto out;
> +
>  	ret = probe_kernel_read(dst, unsafe_ptr, size);
> +out:
>  	if (unlikely(ret < 0))
>  		memset(dst, 0, size);

Hmm, does security_locked_down() ever return a code > 0 or why do you
have the double check on return code? If not, then for clarity the
ret code from security_locked_down() should be checked as 'ret < 0'
as well and out label should be at the memset directly instead.

> @@ -569,6 +574,10 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
>  {
>  	int ret;
>  
> +	ret = security_locked_down(LOCKDOWN_BPF_READ);
> +	if (ret)
> +		goto out;
> +
>  	/*
>  	 * The strncpy_from_unsafe() call will likely not fill the entire
>  	 * buffer, but that's okay in this circumstance as we're probing
> @@ -579,6 +588,7 @@ BPF_CALL_3(bpf_probe_read_str, void *, dst, u32, size,
>  	 * is returned that can be used for bpf_perf_event_output() et al.
>  	 */
>  	ret = strncpy_from_unsafe(dst, unsafe_ptr, size);
> +out:
>  	if (unlikely(ret < 0))
>  		memset(dst, 0, size);

Ditto.

Thanks,
Daniel

Re: [PATCH V35 23/29] bpf: Restrict bpf when kernel lockdown is in confidentiality mode

[Matthew Garrett]

On Mon, Jul 15, 2019 at 3:54 PM Daniel Borkmann <daniel@iogearbox.net> wrote:
> Hmm, does security_locked_down() ever return a code > 0 or why do you
> have the double check on return code? If not, then for clarity the
> ret code from security_locked_down() should be checked as 'ret < 0'
> as well and out label should be at the memset directly instead.

It doesn't, so I'll update. Thanks!

[PATCH V35 24/29] Lock down perf when in confidentiality mode

[Matthew Garrett]

From: David Howells <dhowells@redhat.com>

Disallow the use of certain perf facilities that might allow userspace to
access kernel data.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
---
 include/linux/security.h     | 1 +
 kernel/events/core.c         | 7 +++++++
 security/lockdown/lockdown.c | 1 +
 3 files changed, 9 insertions(+)

diff --git a/include/linux/security.h b/include/linux/security.h
index 8dd1741a52cd..8ef366de70b0 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -119,6 +119,7 @@ enum lockdown_reason {
 	LOCKDOWN_KCORE,
 	LOCKDOWN_KPROBES,
 	LOCKDOWN_BPF_READ,
+	LOCKDOWN_PERF,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
 
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 785d708f8553..738d6f1cf5ec 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -10806,6 +10806,13 @@ SYSCALL_DEFINE5(perf_event_open,
 	    perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
 		return -EACCES;
 
+	err = security_locked_down(LOCKDOWN_PERF);
+	if (err && (attr.sample_type & PERF_SAMPLE_REGS_INTR))
+		/* REGS_INTR can leak data, lockdown must prevent this */
+		return err;
+
+	err = 0;
+
 	/*
 	 * In cgroup mode, the pid argument is used to pass the fd
 	 * opened to the cgroup directory in cgroupfs. The cpu argument
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index d14b89784412..e43c9d001e49 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -34,6 +34,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_KCORE] = "/proc/kcore access",
 	[LOCKDOWN_KPROBES] = "use of kprobes",
 	[LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM",
+	[LOCKDOWN_PERF] = "unsafe use of perf",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
 
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 25/29] kexec: Allow kexec_file() with appropriate IMA policy when locked down

[Matthew Garrett]

Systems in lockdown mode should block the kexec of untrusted kernels.
For x86 and ARM we can ensure that a kernel is trustworthy by validating
a PE signature, but this isn't possible on other architectures. On those
platforms we can use IMA digital signatures instead. Add a function to
determine whether IMA has or will verify signatures for a given event type,
and if so permit kexec_file() even if the kernel is otherwise locked down.
This is restricted to cases where CONFIG_INTEGRITY_TRUSTED_KEYRING is set
in order to prevent an attacker from loading additional keys at runtime.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Mimi Zohar <zohar@linux.ibm.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: linux-integrity@vger.kernel.org
---
 include/linux/ima.h                 |  9 ++++++
 kernel/kexec_file.c                 | 12 +++++--
 security/integrity/ima/ima.h        |  2 ++
 security/integrity/ima/ima_main.c   |  2 +-
 security/integrity/ima/ima_policy.c | 50 +++++++++++++++++++++++++++++
 5 files changed, 72 insertions(+), 3 deletions(-)

diff --git a/include/linux/ima.h b/include/linux/ima.h
index a20ad398d260..1c37f17f7203 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -131,4 +131,13 @@ static inline int ima_inode_removexattr(struct dentry *dentry,
 	return 0;
 }
 #endif /* CONFIG_IMA_APPRAISE */
+
+#if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING)
+extern bool ima_appraise_signature(enum kernel_read_file_id func);
+#else
+static inline bool ima_appraise_signature(enum kernel_read_file_id func)
+{
+	return false;
+}
+#endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */
 #endif /* _LINUX_IMA_H */
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index dd06f1070d66..13c9960a5860 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -228,9 +228,17 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
 			goto out;
 		}
 
-		ret = security_locked_down(LOCKDOWN_KEXEC);
-		if (ret)
+		ret = 0;
+
+		/* If IMA is guaranteed to appraise a signature on the kexec
+		 * image, permit it even if the kernel is otherwise locked
+		 * down.
+		 */
+		if (!ima_appraise_signature(READING_KEXEC_IMAGE) &&
+		    security_locked_down(LOCKDOWN_KEXEC)) {
+			ret = -EPERM;
 			goto out;
+		}
 
 		break;
 
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 011b91c79351..64dcb11cf444 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -113,6 +113,8 @@ struct ima_kexec_hdr {
 	u64 count;
 };
 
+extern const int read_idmap[];
+
 #ifdef CONFIG_HAVE_IMA_KEXEC
 void ima_load_kexec_buffer(void);
 #else
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 584019728660..b9f57503af2c 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -502,7 +502,7 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
 	return 0;
 }
 
-static const int read_idmap[READING_MAX_ID] = {
+const int read_idmap[READING_MAX_ID] = {
 	[READING_FIRMWARE] = FIRMWARE_CHECK,
 	[READING_FIRMWARE_PREALLOC_BUFFER] = FIRMWARE_CHECK,
 	[READING_MODULE] = MODULE_CHECK,
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 6df7f641ff66..827f1e33fe86 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -1456,3 +1456,53 @@ int ima_policy_show(struct seq_file *m, void *v)
 	return 0;
 }
 #endif	/* CONFIG_IMA_READ_POLICY */
+
+#if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING)
+/*
+ * ima_appraise_signature: whether IMA will appraise a given function using
+ * an IMA digital signature. This is restricted to cases where the kernel
+ * has a set of built-in trusted keys in order to avoid an attacker simply
+ * loading additional keys.
+ */
+bool ima_appraise_signature(enum kernel_read_file_id id)
+{
+	struct ima_rule_entry *entry;
+	bool found = false;
+	enum ima_hooks func;
+
+	if (id >= READING_MAX_ID)
+		return false;
+
+	func = read_idmap[id] ?: FILE_CHECK;
+
+	rcu_read_lock();
+	list_for_each_entry_rcu(entry, ima_rules, list) {
+		if (entry->action != APPRAISE)
+			continue;
+
+		/*
+		 * A generic entry will match, but otherwise require that it
+		 * match the func we're looking for
+		 */
+		if (entry->func && entry->func != func)
+			continue;
+
+		/*
+		 * We require this to be a digital signature, not a raw IMA
+		 * hash.
+		 */
+		if (entry->flags & IMA_DIGSIG_REQUIRED)
+			found = true;
+
+		/*
+		 * We've found a rule that matches, so break now even if it
+		 * didn't require a digital signature - a later rule that does
+		 * won't override it, so would be a false positive.
+		 */
+		break;
+	}
+
+	rcu_read_unlock();
+	return found;
+}
+#endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 26/29] debugfs: Restrict debugfs when the kernel is locked down

[Matthew Garrett]

From: David Howells <dhowells@redhat.com>

Disallow opening of debugfs files that might be used to muck around when
the kernel is locked down as various drivers give raw access to hardware
through debugfs.  Given the effort of auditing all 2000 or so files and
manually fixing each one as necessary, I've chosen to apply a heuristic
instead.  The following changes are made:

 (1) chmod and chown are disallowed on debugfs objects (though the root dir
     can be modified by mount and remount, but I'm not worried about that).

 (2) When the kernel is locked down, only files with the following criteria
     are permitted to be opened:

	- The file must have mode 00444
	- The file must not have ioctl methods
	- The file must not have mmap

 (3) When the kernel is locked down, files may only be opened for reading.

Normal device interaction should be done through configfs, sysfs or a
miscdev, not debugfs.

Note that this makes it unnecessary to specifically lock down show_dsts(),
show_devs() and show_call() in the asus-wmi driver.

I would actually prefer to lock down all files by default and have the
the files unlocked by the creator.  This is tricky to manage correctly,
though, as there are 19 creation functions and ~1600 call sites (some of
them in loops scanning tables).

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Andy Shevchenko <andy.shevchenko@gmail.com>
cc: acpi4asus-user@lists.sourceforge.net
cc: platform-driver-x86@vger.kernel.org
cc: Matthew Garrett <mjg59@srcf.ucam.org>
cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Matthew Garrett <matthewgarrett@google.com>
---
 fs/debugfs/file.c            | 30 ++++++++++++++++++++++++++++++
 fs/debugfs/inode.c           | 32 ++++++++++++++++++++++++++++++--
 include/linux/security.h     |  1 +
 security/lockdown/lockdown.c |  1 +
 4 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 93e4ca6b2ad7..87846aad594b 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -19,6 +19,7 @@
 #include <linux/atomic.h>
 #include <linux/device.h>
 #include <linux/poll.h>
+#include <linux/security.h>
 
 #include "internal.h"
 
@@ -136,6 +137,25 @@ void debugfs_file_put(struct dentry *dentry)
 }
 EXPORT_SYMBOL_GPL(debugfs_file_put);
 
+/*
+ * Only permit access to world-readable files when the kernel is locked down.
+ * We also need to exclude any file that has ways to write or alter it as root
+ * can bypass the permissions check.
+ */
+static bool debugfs_is_locked_down(struct inode *inode,
+				   struct file *filp,
+				   const struct file_operations *real_fops)
+{
+	if ((inode->i_mode & 07777) == 0444 &&
+	    !(filp->f_mode & FMODE_WRITE) &&
+	    !real_fops->unlocked_ioctl &&
+	    !real_fops->compat_ioctl &&
+	    !real_fops->mmap)
+		return false;
+
+	return security_locked_down(LOCKDOWN_DEBUGFS);
+}
+
 static int open_proxy_open(struct inode *inode, struct file *filp)
 {
 	struct dentry *dentry = F_DENTRY(filp);
@@ -147,6 +167,11 @@ static int open_proxy_open(struct inode *inode, struct file *filp)
 		return r == -EIO ? -ENOENT : r;
 
 	real_fops = debugfs_real_fops(filp);
+
+	r = debugfs_is_locked_down(inode, filp, real_fops);
+	if (r)
+		goto out;
+
 	real_fops = fops_get(real_fops);
 	if (!real_fops) {
 		/* Huh? Module did not clean up after itself at exit? */
@@ -272,6 +297,11 @@ static int full_proxy_open(struct inode *inode, struct file *filp)
 		return r == -EIO ? -ENOENT : r;
 
 	real_fops = debugfs_real_fops(filp);
+
+	r = debugfs_is_locked_down(inode, filp, real_fops);
+	if (r)
+		goto out;
+
 	real_fops = fops_get(real_fops);
 	if (!real_fops) {
 		/* Huh? Module did not cleanup after itself at exit? */
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 042b688ed124..7b975dbb2bb4 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -26,6 +26,7 @@
 #include <linux/parser.h>
 #include <linux/magic.h>
 #include <linux/slab.h>
+#include <linux/security.h>
 
 #include "internal.h"
 
@@ -35,6 +36,32 @@ static struct vfsmount *debugfs_mount;
 static int debugfs_mount_count;
 static bool debugfs_registered;
 
+/*
+ * Don't allow access attributes to be changed whilst the kernel is locked down
+ * so that we can use the file mode as part of a heuristic to determine whether
+ * to lock down individual files.
+ */
+static int debugfs_setattr(struct dentry *dentry, struct iattr *ia)
+{
+	int ret = security_locked_down(LOCKDOWN_DEBUGFS);
+
+	if (ret && (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
+		return ret;
+	return simple_setattr(dentry, ia);
+}
+
+static const struct inode_operations debugfs_file_inode_operations = {
+	.setattr	= debugfs_setattr,
+};
+static const struct inode_operations debugfs_dir_inode_operations = {
+	.lookup		= simple_lookup,
+	.setattr	= debugfs_setattr,
+};
+static const struct inode_operations debugfs_symlink_inode_operations = {
+	.get_link	= simple_get_link,
+	.setattr	= debugfs_setattr,
+};
+
 static struct inode *debugfs_get_inode(struct super_block *sb)
 {
 	struct inode *inode = new_inode(sb);
@@ -369,6 +396,7 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
 	inode->i_mode = mode;
 	inode->i_private = data;
 
+	inode->i_op = &debugfs_file_inode_operations;
 	inode->i_fop = proxy_fops;
 	dentry->d_fsdata = (void *)((unsigned long)real_fops |
 				DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
@@ -532,7 +560,7 @@ struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
 	}
 
 	inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
-	inode->i_op = &simple_dir_inode_operations;
+	inode->i_op = &debugfs_dir_inode_operations;
 	inode->i_fop = &simple_dir_operations;
 
 	/* directory inodes start off with i_nlink == 2 (for "." entry) */
@@ -632,7 +660,7 @@ struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
 		return failed_creating(dentry);
 	}
 	inode->i_mode = S_IFLNK | S_IRWXUGO;
-	inode->i_op = &simple_symlink_inode_operations;
+	inode->i_op = &debugfs_symlink_inode_operations;
 	inode->i_link = link;
 	d_instantiate(dentry, inode);
 	return end_creating(dentry);
diff --git a/include/linux/security.h b/include/linux/security.h
index 8ef366de70b0..d92323b44a3f 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -115,6 +115,7 @@ enum lockdown_reason {
 	LOCKDOWN_TIOCSSERIAL,
 	LOCKDOWN_MODULE_PARAMETERS,
 	LOCKDOWN_MMIOTRACE,
+	LOCKDOWN_DEBUGFS,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_KCORE,
 	LOCKDOWN_KPROBES,
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index e43c9d001e49..37ef46320ef4 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -30,6 +30,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
 	[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
 	[LOCKDOWN_MMIOTRACE] = "unsafe mmio",
+	[LOCKDOWN_DEBUGFS] = "debugfs access",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_KCORE] = "/proc/kcore access",
 	[LOCKDOWN_KPROBES] = "use of kprobes",
-- 
2.22.0.510.g264f2c817a-goog

Re: [PATCH V35 26/29] debugfs: Restrict debugfs when the kernel is locked down

[James Morris]

On Mon, 15 Jul 2019, Matthew Garrett wrote:

> From: David Howells <dhowells@redhat.com>
> 
> Disallow opening of debugfs files that might be used to muck around when
> the kernel is locked down as various drivers give raw access to hardware
> through debugfs.  Given the effort of auditing all 2000 or so files and
> manually fixing each one as necessary, I've chosen to apply a heuristic
> instead.  The following changes are made:

Adding the debugfs maintainers.

> 
>  (1) chmod and chown are disallowed on debugfs objects (though the root dir
>      can be modified by mount and remount, but I'm not worried about that).
> 
>  (2) When the kernel is locked down, only files with the following criteria
>      are permitted to be opened:
> 
> 	- The file must have mode 00444
> 	- The file must not have ioctl methods
> 	- The file must not have mmap
> 
>  (3) When the kernel is locked down, files may only be opened for reading.
> 
> Normal device interaction should be done through configfs, sysfs or a
> miscdev, not debugfs.
> 
> Note that this makes it unnecessary to specifically lock down show_dsts(),
> show_devs() and show_call() in the asus-wmi driver.
> 
> I would actually prefer to lock down all files by default and have the
> the files unlocked by the creator.  This is tricky to manage correctly,
> though, as there are 19 creation functions and ~1600 call sites (some of
> them in loops scanning tables).
> 
> Signed-off-by: David Howells <dhowells@redhat.com>
> cc: Andy Shevchenko <andy.shevchenko@gmail.com>
> cc: acpi4asus-user@lists.sourceforge.net
> cc: platform-driver-x86@vger.kernel.org
> cc: Matthew Garrett <mjg59@srcf.ucam.org>
> cc: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Matthew Garrett <matthewgarrett@google.com>
> ---
>  fs/debugfs/file.c            | 30 ++++++++++++++++++++++++++++++
>  fs/debugfs/inode.c           | 32 ++++++++++++++++++++++++++++++--
>  include/linux/security.h     |  1 +
>  security/lockdown/lockdown.c |  1 +
>  4 files changed, 62 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
> index 93e4ca6b2ad7..87846aad594b 100644
> --- a/fs/debugfs/file.c
> +++ b/fs/debugfs/file.c
> @@ -19,6 +19,7 @@
>  #include <linux/atomic.h>
>  #include <linux/device.h>
>  #include <linux/poll.h>
> +#include <linux/security.h>
>  
>  #include "internal.h"
>  
> @@ -136,6 +137,25 @@ void debugfs_file_put(struct dentry *dentry)
>  }
>  EXPORT_SYMBOL_GPL(debugfs_file_put);
>  
> +/*
> + * Only permit access to world-readable files when the kernel is locked down.
> + * We also need to exclude any file that has ways to write or alter it as root
> + * can bypass the permissions check.
> + */
> +static bool debugfs_is_locked_down(struct inode *inode,
> +				   struct file *filp,
> +				   const struct file_operations *real_fops)
> +{
> +	if ((inode->i_mode & 07777) == 0444 &&
> +	    !(filp->f_mode & FMODE_WRITE) &&
> +	    !real_fops->unlocked_ioctl &&
> +	    !real_fops->compat_ioctl &&
> +	    !real_fops->mmap)
> +		return false;
> +
> +	return security_locked_down(LOCKDOWN_DEBUGFS);
> +}
> +
>  static int open_proxy_open(struct inode *inode, struct file *filp)
>  {
>  	struct dentry *dentry = F_DENTRY(filp);
> @@ -147,6 +167,11 @@ static int open_proxy_open(struct inode *inode, struct file *filp)
>  		return r == -EIO ? -ENOENT : r;
>  
>  	real_fops = debugfs_real_fops(filp);
> +
> +	r = debugfs_is_locked_down(inode, filp, real_fops);
> +	if (r)
> +		goto out;
> +
>  	real_fops = fops_get(real_fops);
>  	if (!real_fops) {
>  		/* Huh? Module did not clean up after itself at exit? */
> @@ -272,6 +297,11 @@ static int full_proxy_open(struct inode *inode, struct file *filp)
>  		return r == -EIO ? -ENOENT : r;
>  
>  	real_fops = debugfs_real_fops(filp);
> +
> +	r = debugfs_is_locked_down(inode, filp, real_fops);
> +	if (r)
> +		goto out;
> +
>  	real_fops = fops_get(real_fops);
>  	if (!real_fops) {
>  		/* Huh? Module did not cleanup after itself at exit? */
> diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
> index 042b688ed124..7b975dbb2bb4 100644
> --- a/fs/debugfs/inode.c
> +++ b/fs/debugfs/inode.c
> @@ -26,6 +26,7 @@
>  #include <linux/parser.h>
>  #include <linux/magic.h>
>  #include <linux/slab.h>
> +#include <linux/security.h>
>  
>  #include "internal.h"
>  
> @@ -35,6 +36,32 @@ static struct vfsmount *debugfs_mount;
>  static int debugfs_mount_count;
>  static bool debugfs_registered;
>  
> +/*
> + * Don't allow access attributes to be changed whilst the kernel is locked down
> + * so that we can use the file mode as part of a heuristic to determine whether
> + * to lock down individual files.
> + */
> +static int debugfs_setattr(struct dentry *dentry, struct iattr *ia)
> +{
> +	int ret = security_locked_down(LOCKDOWN_DEBUGFS);
> +
> +	if (ret && (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
> +		return ret;
> +	return simple_setattr(dentry, ia);
> +}
> +
> +static const struct inode_operations debugfs_file_inode_operations = {
> +	.setattr	= debugfs_setattr,
> +};
> +static const struct inode_operations debugfs_dir_inode_operations = {
> +	.lookup		= simple_lookup,
> +	.setattr	= debugfs_setattr,
> +};
> +static const struct inode_operations debugfs_symlink_inode_operations = {
> +	.get_link	= simple_get_link,
> +	.setattr	= debugfs_setattr,
> +};
> +
>  static struct inode *debugfs_get_inode(struct super_block *sb)
>  {
>  	struct inode *inode = new_inode(sb);
> @@ -369,6 +396,7 @@ static struct dentry *__debugfs_create_file(const char *name, umode_t mode,
>  	inode->i_mode = mode;
>  	inode->i_private = data;
>  
> +	inode->i_op = &debugfs_file_inode_operations;
>  	inode->i_fop = proxy_fops;
>  	dentry->d_fsdata = (void *)((unsigned long)real_fops |
>  				DEBUGFS_FSDATA_IS_REAL_FOPS_BIT);
> @@ -532,7 +560,7 @@ struct dentry *debugfs_create_dir(const char *name, struct dentry *parent)
>  	}
>  
>  	inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO;
> -	inode->i_op = &simple_dir_inode_operations;
> +	inode->i_op = &debugfs_dir_inode_operations;
>  	inode->i_fop = &simple_dir_operations;
>  
>  	/* directory inodes start off with i_nlink == 2 (for "." entry) */
> @@ -632,7 +660,7 @@ struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent,
>  		return failed_creating(dentry);
>  	}
>  	inode->i_mode = S_IFLNK | S_IRWXUGO;
> -	inode->i_op = &simple_symlink_inode_operations;
> +	inode->i_op = &debugfs_symlink_inode_operations;
>  	inode->i_link = link;
>  	d_instantiate(dentry, inode);
>  	return end_creating(dentry);
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 8ef366de70b0..d92323b44a3f 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -115,6 +115,7 @@ enum lockdown_reason {
>  	LOCKDOWN_TIOCSSERIAL,
>  	LOCKDOWN_MODULE_PARAMETERS,
>  	LOCKDOWN_MMIOTRACE,
> +	LOCKDOWN_DEBUGFS,
>  	LOCKDOWN_INTEGRITY_MAX,
>  	LOCKDOWN_KCORE,
>  	LOCKDOWN_KPROBES,
> diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
> index e43c9d001e49..37ef46320ef4 100644
> --- a/security/lockdown/lockdown.c
> +++ b/security/lockdown/lockdown.c
> @@ -30,6 +30,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
>  	[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
>  	[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
>  	[LOCKDOWN_MMIOTRACE] = "unsafe mmio",
> +	[LOCKDOWN_DEBUGFS] = "debugfs access",
>  	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
>  	[LOCKDOWN_KCORE] = "/proc/kcore access",
>  	[LOCKDOWN_KPROBES] = "use of kprobes",
> 

-- 
James Morris
<jmorris@namei.org>

[PATCH V35 27/29] tracefs: Restrict tracefs when the kernel is locked down

[Matthew Garrett]

Tracefs may release more information about the kernel than desirable, so
restrict it when the kernel is locked down in confidentiality mode by
preventing open().

Signed-off-by: Matthew Garrett <mjg59@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
---
 fs/tracefs/inode.c           | 38 +++++++++++++++++++++++++++++++++++-
 include/linux/security.h     |  1 +
 security/lockdown/lockdown.c |  1 +
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c
index eeeae0475da9..4c04c0c89514 100644
--- a/fs/tracefs/inode.c
+++ b/fs/tracefs/inode.c
@@ -20,6 +20,7 @@
 #include <linux/parser.h>
 #include <linux/magic.h>
 #include <linux/slab.h>
+#include <linux/security.h>
 
 #define TRACEFS_DEFAULT_MODE	0700
 
@@ -27,6 +28,23 @@ static struct vfsmount *tracefs_mount;
 static int tracefs_mount_count;
 static bool tracefs_registered;
 
+static int default_open_file(struct inode *inode, struct file *filp)
+{
+	struct dentry *dentry = filp->f_path.dentry;
+	struct file_operations *real_fops;
+	int ret;
+
+	if (!dentry)
+		return -EINVAL;
+
+	ret = security_locked_down(LOCKDOWN_TRACEFS);
+	if (ret)
+		return ret;
+
+	real_fops = dentry->d_fsdata;
+	return real_fops->open(inode, filp);
+}
+
 static ssize_t default_read_file(struct file *file, char __user *buf,
 				 size_t count, loff_t *ppos)
 {
@@ -221,6 +239,12 @@ static int tracefs_apply_options(struct super_block *sb)
 	return 0;
 }
 
+static void tracefs_destroy_inode(struct inode *inode)
+{
+	if (S_ISREG(inode->i_mode))
+		kfree(inode->i_fop);
+}
+
 static int tracefs_remount(struct super_block *sb, int *flags, char *data)
 {
 	int err;
@@ -256,6 +280,7 @@ static int tracefs_show_options(struct seq_file *m, struct dentry *root)
 
 static const struct super_operations tracefs_super_operations = {
 	.statfs		= simple_statfs,
+	.destroy_inode  = tracefs_destroy_inode,
 	.remount_fs	= tracefs_remount,
 	.show_options	= tracefs_show_options,
 };
@@ -389,6 +414,7 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
 {
 	struct dentry *dentry;
 	struct inode *inode;
+	struct file_operations *proxy_fops;
 
 	if (!(mode & S_IFMT))
 		mode |= S_IFREG;
@@ -402,8 +428,18 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
 	if (unlikely(!inode))
 		return failed_creating(dentry);
 
+	proxy_fops = kzalloc(sizeof(struct file_operations), GFP_KERNEL);
+	if (!proxy_fops)
+		return failed_creating(dentry);
+
+	if (fops)
+		fops = &tracefs_file_operations;
+
+	dentry->d_fsdata = (void *)fops;
+	memcpy(proxy_fops, fops, sizeof(*proxy_fops));
+	proxy_fops->open = default_open_file;
 	inode->i_mode = mode;
-	inode->i_fop = fops ? fops : &tracefs_file_operations;
+	inode->i_fop = proxy_fops;
 	inode->i_private = data;
 	d_instantiate(dentry, inode);
 	fsnotify_create(dentry->d_parent->d_inode, dentry);
diff --git a/include/linux/security.h b/include/linux/security.h
index d92323b44a3f..807dc0d24982 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -121,6 +121,7 @@ enum lockdown_reason {
 	LOCKDOWN_KPROBES,
 	LOCKDOWN_BPF_READ,
 	LOCKDOWN_PERF,
+	LOCKDOWN_TRACEFS,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
 
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 37ef46320ef4..fd7cdbddd814 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -36,6 +36,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_KPROBES] = "use of kprobes",
 	[LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM",
 	[LOCKDOWN_PERF] = "unsafe use of perf",
+	[LOCKDOWN_TRACEFS] = "use of tracefs",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
 
-- 
2.22.0.510.g264f2c817a-goog

Re: [PATCH V35 27/29] tracefs: Restrict tracefs when the kernel is locked down

[Steven Rostedt]

On Mon, 15 Jul 2019 12:59:44 -0700
Matthew Garrett <matthewgarrett@google.com> wrote:

> Tracefs may release more information about the kernel than desirable, so
> restrict it when the kernel is locked down in confidentiality mode by
> preventing open().
> 
> Signed-off-by: Matthew Garrett <mjg59@google.com>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> ---
> 

> @@ -389,6 +414,7 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
>  {
>  	struct dentry *dentry;
>  	struct inode *inode;
> +	struct file_operations *proxy_fops;

Small nit, but please add this as the first declaration, to keep the
"upside-down x-mas tree" look. I know some of the other functions in
this file don't follow that (which should be cleaned up some day), but
I'd like to avoid adding more that breaks the aesthetic of the code.

>  
>  	if (!(mode & S_IFMT))
>  		mode |= S_IFREG;
> @@ -402,8 +428,18 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode,
>  	if (unlikely(!inode))
>  		return failed_creating(dentry);
>  
> +	proxy_fops = kzalloc(sizeof(struct file_operations), GFP_KERNEL);
> +	if (!proxy_fops)
> +		return failed_creating(dentry);
> +
> +	if (fops)

I think you meant "if (!fops)".

-- Steve

> +		fops = &tracefs_file_operations;
> +
> +	dentry->d_fsdata = (void *)fops;
> +	memcpy(proxy_fops, fops, sizeof(*proxy_fops));
> +	proxy_fops->open = default_open_file;
>  	inode->i_mode = mode;
> -	inode->i_fop = fops ? fops : &tracefs_file_operations;
> +	inode->i_fop = proxy_fops;
>  	inode->i_private = data;
>  	d_instantiate(dentry, inode);
>  	fsnotify_create(dentry->d_parent->d_inode, dentry);

Re: [PATCH V35 27/29] tracefs: Restrict tracefs when the kernel is locked down

[Matthew Garrett]

On Tue, Jul 16, 2019 at 4:14 PM Steven Rostedt <rostedt@goodmis.org> wrote:
> Small nit, but please add this as the first declaration, to keep the
> "upside-down x-mas tree" look. I know some of the other functions in
> this file don't follow that (which should be cleaned up some day), but
> I'd like to avoid adding more that breaks the aesthetic of the code.

ACK.

> > +
> > +     if (fops)
>
> I think you meant "if (!fops)".

Blink. Whoops! Yup.

[PATCH V35 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down

[Matthew Garrett]

efivar_ssdt_load allows the kernel to import arbitrary ACPI code from an
EFI variable, which gives arbitrary code execution in ring 0. Prevent
that when the kernel is locked down.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-efi@vger.kernel.org
---
 drivers/firmware/efi/efi.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index ad3b1f4866b3..776f479e5499 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -30,6 +30,7 @@
 #include <linux/acpi.h>
 #include <linux/ucs2_string.h>
 #include <linux/memblock.h>
+#include <linux/security.h>
 
 #include <asm/early_ioremap.h>
 
@@ -242,6 +243,11 @@ static void generic_ops_unregister(void)
 static char efivar_ssdt[EFIVAR_SSDT_NAME_MAX] __initdata;
 static int __init efivar_ssdt_setup(char *str)
 {
+	int ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
+
+	if (ret)
+		return ret;
+
 	if (strlen(str) < sizeof(efivar_ssdt))
 		memcpy(efivar_ssdt, str, strlen(str));
 	else
-- 
2.22.0.510.g264f2c817a-goog

[PATCH V35 29/29] lockdown: Print current->comm in restriction messages

[Matthew Garrett]

Print the content of current->comm in messages generated by lockdown to
indicate a restriction that was hit.  This makes it a bit easier to find
out what caused the message.

The message now patterned something like:

        Lockdown: <comm>: <what> is restricted; see man kernel_lockdown.7

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
 fs/proc/kcore.c              | 5 +++--
 security/lockdown/lockdown.c | 8 ++++++--
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c
index ee2c576cc94e..e2ed8e08cc7a 100644
--- a/fs/proc/kcore.c
+++ b/fs/proc/kcore.c
@@ -548,11 +548,12 @@ static int open_kcore(struct inode *inode, struct file *filp)
 {
 	int ret = security_locked_down(LOCKDOWN_KCORE);
 
-	if (ret)
-		return ret;
 	if (!capable(CAP_SYS_RAWIO))
 		return -EPERM;
 
+	if (ret)
+		return ret;
+
 	filp->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!filp->private_data)
 		return -ENOMEM;
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index fd7cdbddd814..bbf30d34542c 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -81,10 +81,14 @@ early_param("lockdown", lockdown_param);
  */
 static int lockdown_is_locked_down(enum lockdown_reason what)
 {
+	if (WARN(what >= LOCKDOWN_CONFIDENTIALITY_MAX,
+		 "Invalid lockdown reason"))
+		return -EPERM;
+
 	if (kernel_locked_down >= what) {
 		if (lockdown_reasons[what])
-			pr_notice("Lockdown: %s is restricted; see man kernel_lockdown.7\n",
-				  lockdown_reasons[what]);
+			pr_notice("Lockdown: %s: %s is restricted; see man kernel_lockdown.7\n",
+				  current->comm, lockdown_reasons[what]);
 		return -EPERM;
 	}
 
-- 
2.22.0.510.g264f2c817a-goog