Merge 3.13-rc5 into staging-next (912cbd49) · Commits · e / devices / android_kernel_oneplus_sm8150

Documentation/module-signing.txt

0 → 100644

+240 −0

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			==============================
			KERNEL MODULE SIGNING FACILITY
			==============================

			CONTENTS

			- Overview.
			- Configuring module signing.
			- Generating signing keys.
			- Public keys in the kernel.
			- Manually signing modules.
			- Signed modules and stripping.
			- Loading signed modules.
			- Non-valid signatures and unsigned modules.
			- Administering/protecting the private key.


			========
			OVERVIEW
			========

			The kernel module signing facility cryptographically signs modules during
			installation and then checks the signature upon loading the module. This
			allows increased kernel security by disallowing the loading of unsigned modules
			or modules signed with an invalid key. Module signing increases security by
			making it harder to load a malicious module into the kernel. The module
			signature checking is done by the kernel so that it is not necessary to have
			trusted userspace bits.

			This facility uses X.509 ITU-T standard certificates to encode the public keys
			involved. The signatures are not themselves encoded in any industrial standard
			type. The facility currently only supports the RSA public key encryption
			standard (though it is pluggable and permits others to be used). The possible
			hash algorithms that can be used are SHA-1, SHA-224, SHA-256, SHA-384, and
			SHA-512 (the algorithm is selected by data in the signature).


			==========================
			CONFIGURING MODULE SIGNING
			==========================

			The module signing facility is enabled by going to the "Enable Loadable Module
			Support" section of the kernel configuration and turning on

			CONFIG_MODULE_SIG "Module signature verification"

			This has a number of options available:

			(1) "Require modules to be validly signed" (CONFIG_MODULE_SIG_FORCE)

			This specifies how the kernel should deal with a module that has a
			signature for which the key is not known or a module that is unsigned.

			If this is off (ie. "permissive"), then modules for which the key is not
			available and modules that are unsigned are permitted, but the kernel will
			be marked as being tainted.

			If this is on (ie. "restrictive"), only modules that have a valid
			signature that can be verified by a public key in the kernel's possession
			will be loaded. All other modules will generate an error.

			Irrespective of the setting here, if the module has a signature block that
			cannot be parsed, it will be rejected out of hand.


			(2) "Automatically sign all modules" (CONFIG_MODULE_SIG_ALL)

			If this is on then modules will be automatically signed during the
			modules_install phase of a build. If this is off, then the modules must
			be signed manually using:

			scripts/sign-file


			(3) "Which hash algorithm should modules be signed with?"

			This presents a choice of which hash algorithm the installation phase will
			sign the modules with:

			CONFIG_SIG_SHA1 "Sign modules with SHA-1"
			CONFIG_SIG_SHA224 "Sign modules with SHA-224"
			CONFIG_SIG_SHA256 "Sign modules with SHA-256"
			CONFIG_SIG_SHA384 "Sign modules with SHA-384"
			CONFIG_SIG_SHA512 "Sign modules with SHA-512"

			The algorithm selected here will also be built into the kernel (rather
			than being a module) so that modules signed with that algorithm can have
			their signatures checked without causing a dependency loop.


			=======================
			GENERATING SIGNING KEYS
			=======================

			Cryptographic keypairs are required to generate and check signatures. A
			private key is used to generate a signature and the corresponding public key is
			used to check it. The private key is only needed during the build, after which
			it can be deleted or stored securely. The public key gets built into the
			kernel so that it can be used to check the signatures as the modules are
			loaded.

			Under normal conditions, the kernel build will automatically generate a new
			keypair using openssl if one does not exist in the files:

			signing_key.priv
			signing_key.x509

			during the building of vmlinux (the public part of the key needs to be built
			into vmlinux) using parameters in the:

			x509.genkey

			file (which is also generated if it does not already exist).

			It is strongly recommended that you provide your own x509.genkey file.

			Most notably, in the x509.genkey file, the req_distinguished_name section
			should be altered from the default:

			[ req_distinguished_name ]
			O = Magrathea
			CN = Glacier signing key
			emailAddress = slartibartfast@magrathea.h2g2

			The generated RSA key size can also be set with:

			[ req ]
			default_bits = 4096


			It is also possible to manually generate the key private/public files using the
			x509.genkey key generation configuration file in the root node of the Linux
			kernel sources tree and the openssl command. The following is an example to
			generate the public/private key files:

			openssl req -new -nodes -utf8 -sha256 -days 36500 -batch -x509 \
			-config x509.genkey -outform DER -out signing_key.x509 \
			-keyout signing_key.priv


			=========================
			PUBLIC KEYS IN THE KERNEL
			=========================

			The kernel contains a ring of public keys that can be viewed by root. They're
			in a keyring called ".system_keyring" that can be seen by:

			[root@deneb ~]# cat /proc/keys
			...
			223c7853 I------ 1 perm 1f030000 0 0 keyring .system_keyring: 1
			302d2d52 I------ 1 perm 1f010000 0 0 asymmetri Fedora kernel signing key: d69a84e6bce3d216b979e9505b3e3ef9a7118079: X509.RSA a7118079 []
			...

			Beyond the public key generated specifically for module signing, any file
			placed in the kernel source root directory or the kernel build root directory
			whose name is suffixed with ".x509" will be assumed to be an X.509 public key
			and will be added to the keyring.

			Further, the architecture code may take public keys from a hardware store and
			add those in also (e.g. from the UEFI key database).

			Finally, it is possible to add additional public keys by doing:

			keyctl padd asymmetric "" [.system_keyring-ID] <[key-file]

			e.g.:

			keyctl padd asymmetric "" 0x223c7853 <my_public_key.x509

			Note, however, that the kernel will only permit keys to be added to
			.system_keyring _if_ the new key's X.509 wrapper is validly signed by a key
			that is already resident in the .system_keyring at the time the key was added.


			=========================
			MANUALLY SIGNING MODULES
			=========================

			To manually sign a module, use the scripts/sign-file tool available in
			the Linux kernel source tree. The script requires 4 arguments:

			1. The hash algorithm (e.g., sha256)
			2. The private key filename
			3. The public key filename
			4. The kernel module to be signed

			The following is an example to sign a kernel module:

			scripts/sign-file sha512 kernel-signkey.priv \
			kernel-signkey.x509 module.ko

			The hash algorithm used does not have to match the one configured, but if it
			doesn't, you should make sure that hash algorithm is either built into the
			kernel or can be loaded without requiring itself.


			============================
			SIGNED MODULES AND STRIPPING
			============================

			A signed module has a digital signature simply appended at the end. The string
			"~Module signature appended~." at the end of the module's file confirms that a
			signature is present but it does not confirm that the signature is valid!

			Signed modules are BRITTLE as the signature is outside of the defined ELF
			container. Thus they MAY NOT be stripped once the signature is computed and
			attached. Note the entire module is the signed payload, including any and all
			debug information present at the time of signing.


			======================
			LOADING SIGNED MODULES
			======================

			Modules are loaded with insmod, modprobe, init_module() or finit_module(),
			exactly as for unsigned modules as no processing is done in userspace. The
			signature checking is all done within the kernel.


			=========================================
			NON-VALID SIGNATURES AND UNSIGNED MODULES
			=========================================

			If CONFIG_MODULE_SIG_FORCE is enabled or enforcemodulesig=1 is supplied on
			the kernel command line, the kernel will only load validly signed modules
			for which it has a public key. Otherwise, it will also load modules that are
			unsigned. Any module for which the kernel has a key, but which proves to have
			a signature mismatch will not be permitted to load.

			Any module that has an unparseable signature will be rejected.


			=========================================
			ADMINISTERING/PROTECTING THE PRIVATE KEY
			=========================================

			Since the private key is used to sign modules, viruses and malware could use
			the private key to sign modules and compromise the operating system. The
			private key must be either destroyed or moved to a secure location and not kept
			in the root node of the kernel source tree.

Documentation/networking/ip-sysctl.txt

+6 −2

Original line number	Original line	Diff line number	Diff line
	@@ -16,8 +16,12 @@ ip_default_ttl - INTEGER
	Default: 64 (as recommended by RFC1700)		Default: 64 (as recommended by RFC1700)

	ip_no_pmtu_disc - BOOLEAN		ip_no_pmtu_disc - BOOLEAN
	Disable Path MTU Discovery.		Disable Path MTU Discovery. If enabled and a
	default FALSE		fragmentation-required ICMP is received, the PMTU to this
			destination will be set to min_pmtu (see below). You will need
			to raise min_pmtu to the smallest interface MTU on your system
			manually if you want to avoid locally generated fragments.
			Default: FALSE

	min_pmtu - INTEGER		min_pmtu - INTEGER
	default 552 - minimum discovered Path MTU		default 552 - minimum discovered Path MTU

MAINTAINERS

+23 −4

Original line number	Original line	Diff line number	Diff line
	@@ -1008,6 +1008,8 @@ M: Santosh Shilimkar <santosh.shilimkar@ti.com>
	L: linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)		L: linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
	S: Maintained		S: Maintained
	F: arch/arm/mach-keystone/		F: arch/arm/mach-keystone/
			F: drivers/clk/keystone/
			T: git git://git.kernel.org/pub/scm/linux/kernel/git/ssantosh/linux-keystone.git

	ARM/LOGICPD PXA270 MACHINE SUPPORT		ARM/LOGICPD PXA270 MACHINE SUPPORT
	M: Lennert Buytenhek <kernel@wantstofly.org>		M: Lennert Buytenhek <kernel@wantstofly.org>
	@@ -3761,9 +3763,11 @@ F: include/uapi/linux/gigaset_dev.h

	GPIO SUBSYSTEM		GPIO SUBSYSTEM
	M: Linus Walleij <linus.walleij@linaro.org>		M: Linus Walleij <linus.walleij@linaro.org>
	S: Maintained		M: Alexandre Courbot <gnurou@gmail.com>
	L: linux-gpio@vger.kernel.org		L: linux-gpio@vger.kernel.org
	F: Documentation/gpio.txt		T: git git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio.git
			S: Maintained
			F: Documentation/gpio/
	F: drivers/gpio/		F: drivers/gpio/
	F: include/linux/gpio*		F: include/linux/gpio*
	F: include/asm-generic/gpio.h		F: include/asm-generic/gpio.h
	@@ -3831,6 +3835,12 @@ T: git git://linuxtv.org/media_tree.git
	S: Maintained		S: Maintained
	F: drivers/media/usb/gspca/		F: drivers/media/usb/gspca/

			GUID PARTITION TABLE (GPT)
			M: Davidlohr Bueso <davidlohr@hp.com>
			L: linux-efi@vger.kernel.org
			S: Maintained
			F: block/partitions/efi.*

	STK1160 USB VIDEO CAPTURE DRIVER		STK1160 USB VIDEO CAPTURE DRIVER
	M: Ezequiel Garcia <elezegarcia@gmail.com>		M: Ezequiel Garcia <elezegarcia@gmail.com>
	L: linux-media@vger.kernel.org		L: linux-media@vger.kernel.org
	@@ -5911,12 +5921,21 @@ M: Steffen Klassert <steffen.klassert@secunet.com>
	M: Herbert Xu <herbert@gondor.apana.org.au>		M: Herbert Xu <herbert@gondor.apana.org.au>
	M: "David S. Miller" <davem@davemloft.net>		M: "David S. Miller" <davem@davemloft.net>
	L: netdev@vger.kernel.org		L: netdev@vger.kernel.org
	T: git git://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git		T: git git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec.git
			T: git git://git.kernel.org/pub/scm/linux/kernel/git/klassert/ipsec-next.git
	S: Maintained		S: Maintained
	F: net/xfrm/		F: net/xfrm/
	F: net/key/		F: net/key/
	F: net/ipv4/xfrm*		F: net/ipv4/xfrm*
			F: net/ipv4/esp4.c
			F: net/ipv4/ah4.c
			F: net/ipv4/ipcomp.c
			F: net/ipv4/ip_vti.c
	F: net/ipv6/xfrm*		F: net/ipv6/xfrm*
			F: net/ipv6/esp6.c
			F: net/ipv6/ah6.c
			F: net/ipv6/ipcomp6.c
			F: net/ipv6/ip6_vti.c
	F: include/uapi/linux/xfrm.h		F: include/uapi/linux/xfrm.h
	F: include/net/xfrm.h		F: include/net/xfrm.h

	@@ -9571,7 +9590,7 @@ F: drivers/xen/swiotlb

	XFS FILESYSTEM		XFS FILESYSTEM
	P: Silicon Graphics Inc		P: Silicon Graphics Inc
	M: Dave Chinner <dchinner@fromorbit.com>		M: Dave Chinner <david@fromorbit.com>
	M: Ben Myers <bpm@sgi.com>		M: Ben Myers <bpm@sgi.com>
	M: xfs@oss.sgi.com		M: xfs@oss.sgi.com
	L: xfs@oss.sgi.com		L: xfs@oss.sgi.com

Makefile

+10 −14

Original line number	Original line	Diff line number	Diff line
	VERSION = 3		VERSION = 3
	PATCHLEVEL = 13		PATCHLEVEL = 13
	SUBLEVEL = 0		SUBLEVEL = 0
	EXTRAVERSION = -rc4		EXTRAVERSION = -rc5
	NAME = One Giant Leap for Frogkind		NAME = One Giant Leap for Frogkind

	# DOCUMENTATION		# DOCUMENTATION
	@@ -732,19 +732,15 @@ export mod_strip_cmd
	# Select initial ramdisk compression format, default is gzip(1).		# Select initial ramdisk compression format, default is gzip(1).
	# This shall be used by the dracut(8) tool while creating an initramfs image.		# This shall be used by the dracut(8) tool while creating an initramfs image.
	#		#
	INITRD_COMPRESS=gzip		INITRD_COMPRESS-y := gzip
	ifeq ($(CONFIG_RD_BZIP2), y)		INITRD_COMPRESS-$(CONFIG_RD_BZIP2) := bzip2
	INITRD_COMPRESS=bzip2		INITRD_COMPRESS-$(CONFIG_RD_LZMA) := lzma
	else ifeq ($(CONFIG_RD_LZMA), y)		INITRD_COMPRESS-$(CONFIG_RD_XZ) := xz
	INITRD_COMPRESS=lzma		INITRD_COMPRESS-$(CONFIG_RD_LZO) := lzo
	else ifeq ($(CONFIG_RD_XZ), y)		INITRD_COMPRESS-$(CONFIG_RD_LZ4) := lz4
	INITRD_COMPRESS=xz		# do not export INITRD_COMPRESS, since we didn't actually
	else ifeq ($(CONFIG_RD_LZO), y)		# choose a sane default compression above.
	INITRD_COMPRESS=lzo		# export INITRD_COMPRESS := $(INITRD_COMPRESS-y)
	else ifeq ($(CONFIG_RD_LZ4), y)
	INITRD_COMPRESS=lz4
	endif
	export INITRD_COMPRESS

	ifdef CONFIG_MODULE_SIG_ALL		ifdef CONFIG_MODULE_SIG_ALL
	MODSECKEY = ./signing_key.priv		MODSECKEY = ./signing_key.priv

arch/arc/include/uapi/asm/unistd.h

+7 −1

Original line number	Original line	Diff line number	Diff line
	@@ -8,7 +8,11 @@

	/****** no-legacy-syscalls-ABI *****/		/****** no-legacy-syscalls-ABI *****/

	#ifndef _UAPI_ASM_ARC_UNISTD_H		/*
			* Non-typical guard macro to enable inclusion twice in ARCH sys.c
			* That is how the Generic syscall wrapper generator works
			*/
			#if !defined(_UAPI_ASM_ARC_UNISTD_H) \|\| defined(__SYSCALL)
	#define _UAPI_ASM_ARC_UNISTD_H		#define _UAPI_ASM_ARC_UNISTD_H

	#define __ARCH_WANT_SYS_EXECVE		#define __ARCH_WANT_SYS_EXECVE
	@@ -36,4 +40,6 @@ __SYSCALL(__NR_arc_gettls, sys_arc_gettls)
	#define __NR_sysfs (__NR_arch_specific_syscall + 3)		#define __NR_sysfs (__NR_arch_specific_syscall + 3)
	__SYSCALL(__NR_sysfs, sys_sysfs)		__SYSCALL(__NR_sysfs, sys_sysfs)

			#undef __SYSCALL

	#endif		#endif