xref: /openbmc/linux/security/Kconfig (revision 4a2d80ad) 
1# SPDX-License-Identifier: GPL-2.0-only
2#
3# Security configuration
4#
5
6menu "Security options"
7
8source "security/keys/Kconfig"
9
10config SECURITY_DMESG_RESTRICT
11	bool "Restrict unprivileged access to the kernel syslog"
12	default n
13	help
14	  This enforces restrictions on unprivileged users reading the kernel
15	  syslog via dmesg(8).
16
17	  If this option is not selected, no restrictions will be enforced
18	  unless the dmesg_restrict sysctl is explicitly set to (1).
19
20	  If you are unsure how to answer this question, answer N.
21
22config SECURITY
23	bool "Enable different security models"
24	depends on SYSFS
25	depends on MULTIUSER
26	help
27	  This allows you to choose different security modules to be
28	  configured into your kernel.
29
30	  If this option is not selected, the default Linux security
31	  model will be used.
32
33	  If you are unsure how to answer this question, answer N.
34
35config SECURITY_WRITABLE_HOOKS
36	depends on SECURITY
37	bool
38	default n
39
40config SECURITYFS
41	bool "Enable the securityfs filesystem"
42	help
43	  This will build the securityfs filesystem.  It is currently used by
44	  various security modules (AppArmor, IMA, SafeSetID, TOMOYO, TPM).
45
46	  If you are unsure how to answer this question, answer N.
47
48config SECURITY_NETWORK
49	bool "Socket and Networking Security Hooks"
50	depends on SECURITY
51	help
52	  This enables the socket and networking security hooks.
53	  If enabled, a security module can use these hooks to
54	  implement socket and networking access controls.
55	  If you are unsure how to answer this question, answer N.
56
57config SECURITY_INFINIBAND
58	bool "Infiniband Security Hooks"
59	depends on SECURITY && INFINIBAND
60	help
61	  This enables the Infiniband security hooks.
62	  If enabled, a security module can use these hooks to
63	  implement Infiniband access controls.
64	  If you are unsure how to answer this question, answer N.
65
66config SECURITY_NETWORK_XFRM
67	bool "XFRM (IPSec) Networking Security Hooks"
68	depends on XFRM && SECURITY_NETWORK
69	help
70	  This enables the XFRM (IPSec) networking security hooks.
71	  If enabled, a security module can use these hooks to
72	  implement per-packet access controls based on labels
73	  derived from IPSec policy.  Non-IPSec communications are
74	  designated as unlabelled, and only sockets authorized
75	  to communicate unlabelled data can send without using
76	  IPSec.
77	  If you are unsure how to answer this question, answer N.
78
79config SECURITY_PATH
80	bool "Security hooks for pathname based access control"
81	depends on SECURITY
82	help
83	  This enables the security hooks for pathname based access control.
84	  If enabled, a security module can use these hooks to
85	  implement pathname based access controls.
86	  If you are unsure how to answer this question, answer N.
87
88config INTEL_TXT
89	bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
90	depends on HAVE_INTEL_TXT
91	help
92	  This option enables support for booting the kernel with the
93	  Trusted Boot (tboot) module. This will utilize
94	  Intel(R) Trusted Execution Technology to perform a measured launch
95	  of the kernel. If the system does not support Intel(R) TXT, this
96	  will have no effect.
97
98	  Intel TXT will provide higher assurance of system configuration and
99	  initial state as well as data reset protection.  This is used to
100	  create a robust initial kernel measurement and verification, which
101	  helps to ensure that kernel security mechanisms are functioning
102	  correctly. This level of protection requires a root of trust outside
103	  of the kernel itself.
104
105	  Intel TXT also helps solve real end user concerns about having
106	  confidence that their hardware is running the VMM or kernel that
107	  it was configured with, especially since they may be responsible for
108	  providing such assurances to VMs and services running on it.
109
110	  See <https://www.intel.com/technology/security/> for more information
111	  about Intel(R) TXT.
112	  See <http://tboot.sourceforge.net> for more information about tboot.
113	  See Documentation/arch/x86/intel_txt.rst for a description of how to enable
114	  Intel TXT support in a kernel boot.
115
116	  If you are unsure as to whether this is required, answer N.
117
118config LSM_MMAP_MIN_ADDR
119	int "Low address space for LSM to protect from user allocation"
120	depends on SECURITY && SECURITY_SELINUX
121	default 32768 if ARM || (ARM64 && COMPAT)
122	default 65536
123	help
124	  This is the portion of low virtual memory which should be protected
125	  from userspace allocation.  Keeping a user from writing to low pages
126	  can help reduce the impact of kernel NULL pointer bugs.
127
128	  For most ia64, ppc64 and x86 users with lots of address space
129	  a value of 65536 is reasonable and should cause no problems.
130	  On arm and other archs it should not be higher than 32768.
131	  Programs which use vm86 functionality or have some need to map
132	  this low address space will need the permission specific to the
133	  systems running LSM.
134
135config HAVE_HARDENED_USERCOPY_ALLOCATOR
136	bool
137	help
138	  The heap allocator implements __check_heap_object() for
139	  validating memory ranges against heap object sizes in
140	  support of CONFIG_HARDENED_USERCOPY.
141
142config HARDENED_USERCOPY
143	bool "Harden memory copies between kernel and userspace"
144	depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
145	imply STRICT_DEVMEM
146	help
147	  This option checks for obviously wrong memory regions when
148	  copying memory to/from the kernel (via copy_to_user() and
149	  copy_from_user() functions) by rejecting memory ranges that
150	  are larger than the specified heap object, span multiple
151	  separately allocated pages, are not on the process stack,
152	  or are part of the kernel text. This prevents entire classes
153	  of heap overflow exploits and similar kernel memory exposures.
154
155config FORTIFY_SOURCE
156	bool "Harden common str/mem functions against buffer overflows"
157	depends on ARCH_HAS_FORTIFY_SOURCE
158	# https://bugs.llvm.org/show_bug.cgi?id=41459
159	depends on !CC_IS_CLANG || CLANG_VERSION >= 120001
160	# https://github.com/llvm/llvm-project/issues/53645
161	depends on !CC_IS_CLANG || !X86_32
162	help
163	  Detect overflows of buffers in common string and memory functions
164	  where the compiler can determine and validate the buffer sizes.
165
166config STATIC_USERMODEHELPER
167	bool "Force all usermode helper calls through a single binary"
168	help
169	  By default, the kernel can call many different userspace
170	  binary programs through the "usermode helper" kernel
171	  interface.  Some of these binaries are statically defined
172	  either in the kernel code itself, or as a kernel configuration
173	  option.  However, some of these are dynamically created at
174	  runtime, or can be modified after the kernel has started up.
175	  To provide an additional layer of security, route all of these
176	  calls through a single executable that can not have its name
177	  changed.
178
179	  Note, it is up to this single binary to then call the relevant
180	  "real" usermode helper binary, based on the first argument
181	  passed to it.  If desired, this program can filter and pick
182	  and choose what real programs are called.
183
184	  If you wish for all usermode helper programs are to be
185	  disabled, choose this option and then set
186	  STATIC_USERMODEHELPER_PATH to an empty string.
187
188config STATIC_USERMODEHELPER_PATH
189	string "Path to the static usermode helper binary"
190	depends on STATIC_USERMODEHELPER
191	default "/sbin/usermode-helper"
192	help
193	  The binary called by the kernel when any usermode helper
194	  program is wish to be run.  The "real" application's name will
195	  be in the first argument passed to this program on the command
196	  line.
197
198	  If you wish for all usermode helper programs to be disabled,
199	  specify an empty string here (i.e. "").
200
201source "security/selinux/Kconfig"
202source "security/smack/Kconfig"
203source "security/tomoyo/Kconfig"
204source "security/apparmor/Kconfig"
205source "security/loadpin/Kconfig"
206source "security/yama/Kconfig"
207source "security/safesetid/Kconfig"
208source "security/lockdown/Kconfig"
209source "security/landlock/Kconfig"
210
211source "security/integrity/Kconfig"
212
213choice
214	prompt "First legacy 'major LSM' to be initialized"
215	default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
216	default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
217	default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
218	default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
219	default DEFAULT_SECURITY_DAC
220
221	help
222	  This choice is there only for converting CONFIG_DEFAULT_SECURITY
223	  in old kernel configs to CONFIG_LSM in new kernel configs. Don't
224	  change this choice unless you are creating a fresh kernel config,
225	  for this choice will be ignored after CONFIG_LSM has been set.
226
227	  Selects the legacy "major security module" that will be
228	  initialized first. Overridden by non-default CONFIG_LSM.
229
230	config DEFAULT_SECURITY_SELINUX
231		bool "SELinux" if SECURITY_SELINUX=y
232
233	config DEFAULT_SECURITY_SMACK
234		bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
235
236	config DEFAULT_SECURITY_TOMOYO
237		bool "TOMOYO" if SECURITY_TOMOYO=y
238
239	config DEFAULT_SECURITY_APPARMOR
240		bool "AppArmor" if SECURITY_APPARMOR=y
241
242	config DEFAULT_SECURITY_DAC
243		bool "Unix Discretionary Access Controls"
244
245endchoice
246
247config LSM
248	string "Ordered list of enabled LSMs"
249	default "landlock,lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
250	default "landlock,lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
251	default "landlock,lockdown,yama,loadpin,safesetid,integrity,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
252	default "landlock,lockdown,yama,loadpin,safesetid,integrity,bpf" if DEFAULT_SECURITY_DAC
253	default "landlock,lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor,bpf"
254	help
255	  A comma-separated list of LSMs, in initialization order.
256	  Any LSMs left off this list will be ignored. This can be
257	  controlled at boot with the "lsm=" parameter.
258
259	  If unsure, leave this as the default.
260
261source "security/Kconfig.hardening"
262
263endmenu
264
265