Merge tag 'omap-for-v3.13/intc-ldp-fix' of... (9b17c165) · Commits · 戴 / test

Documentation/module-signing.txt

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

		ip_no_pmtu_disc - BOOLEAN
		Disable Path MTU Discovery.
		default FALSE
		Disable Path MTU Discovery. If enabled and a
		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
		default 552 - minimum discovered Path MTU

MAINTAINERS

+21 −4

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		@@ -3763,9 +3763,11 @@ F: include/uapi/linux/gigaset_dev.h

		GPIO SUBSYSTEM
		M: Linus Walleij <linus.walleij@linaro.org>
		S: Maintained
		M: Alexandre Courbot <gnurou@gmail.com>
		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: include/linux/gpio*
		F: include/asm-generic/gpio.h
		@@ -3833,6 +3835,12 @@ T: git git://linuxtv.org/media_tree.git
		S: Maintained
		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
		M: Ezequiel Garcia <elezegarcia@gmail.com>
		L: linux-media@vger.kernel.org
		@@ -5913,12 +5921,21 @@ M: Steffen Klassert <steffen.klassert@secunet.com>
		M: Herbert Xu <herbert@gondor.apana.org.au>
		M: "David S. Miller" <davem@davemloft.net>
		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
		F: net/xfrm/
		F: net/key/
		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/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/net/xfrm.h

		@@ -9573,7 +9590,7 @@ F: drivers/xen/swiotlb

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

Makefile

+10 −14

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

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

		ifdef CONFIG_MODULE_SIG_ALL
		MODSECKEY = ./signing_key.priv

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

+7 −1

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		@@ -8,7 +8,11 @@

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

		#undef __SYSCALL

		#endif

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