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