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://bugs.llvm.org/show_bug.cgi?id=41459
146	depends on !CC_IS_CLANG || CLANG_VERSION >= 120001
147	# https://github.com/llvm/llvm-project/issues/53645
148	depends on !CC_IS_CLANG || !X86_32
149	help
150	  Detect overflows of buffers in common string and memory functions
151	  where the compiler can determine and validate the buffer sizes.
152
153config STATIC_USERMODEHELPER
154	bool "Force all usermode helper calls through a single binary"
155	help
156	  By default, the kernel can call many different userspace
157	  binary programs through the "usermode helper" kernel
158	  interface.  Some of these binaries are statically defined
159	  either in the kernel code itself, or as a kernel configuration
160	  option.  However, some of these are dynamically created at
161	  runtime, or can be modified after the kernel has started up.
162	  To provide an additional layer of security, route all of these
163	  calls through a single executable that can not have its name
164	  changed.
165
166	  Note, it is up to this single binary to then call the relevant
167	  "real" usermode helper binary, based on the first argument
168	  passed to it.  If desired, this program can filter and pick
169	  and choose what real programs are called.
170
171	  If you wish for all usermode helper programs are to be
172	  disabled, choose this option and then set
173	  STATIC_USERMODEHELPER_PATH to an empty string.
174
175config STATIC_USERMODEHELPER_PATH
176	string "Path to the static usermode helper binary"
177	depends on STATIC_USERMODEHELPER
178	default "/sbin/usermode-helper"
179	help
180	  The binary called by the kernel when any usermode helper
181	  program is wish to be run.  The "real" application's name will
182	  be in the first argument passed to this program on the command
183	  line.
184
185	  If you wish for all usermode helper programs to be disabled,
186	  specify an empty string here (i.e. "").
187
188source "security/selinux/Kconfig"
189source "security/smack/Kconfig"
190source "security/tomoyo/Kconfig"
191source "security/apparmor/Kconfig"
192source "security/loadpin/Kconfig"
193source "security/yama/Kconfig"
194source "security/safesetid/Kconfig"
195source "security/lockdown/Kconfig"
196source "security/landlock/Kconfig"
197
198source "security/integrity/Kconfig"
199
200choice
201	prompt "First legacy 'major LSM' to be initialized"
202	default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
203	default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
204	default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
205	default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
206	default DEFAULT_SECURITY_DAC
207
208	help
209	  This choice is there only for converting CONFIG_DEFAULT_SECURITY
210	  in old kernel configs to CONFIG_LSM in new kernel configs. Don't
211	  change this choice unless you are creating a fresh kernel config,
212	  for this choice will be ignored after CONFIG_LSM has been set.
213
214	  Selects the legacy "major security module" that will be
215	  initialized first. Overridden by non-default CONFIG_LSM.
216
217	config DEFAULT_SECURITY_SELINUX
218		bool "SELinux" if SECURITY_SELINUX=y
219
220	config DEFAULT_SECURITY_SMACK
221		bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
222
223	config DEFAULT_SECURITY_TOMOYO
224		bool "TOMOYO" if SECURITY_TOMOYO=y
225
226	config DEFAULT_SECURITY_APPARMOR
227		bool "AppArmor" if SECURITY_APPARMOR=y
228
229	config DEFAULT_SECURITY_DAC
230		bool "Unix Discretionary Access Controls"
231
232endchoice
233
234config LSM
235	string "Ordered list of enabled LSMs"
236	default "landlock,lockdown,yama,loadpin,safesetid,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
237	default "landlock,lockdown,yama,loadpin,safesetid,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
238	default "landlock,lockdown,yama,loadpin,safesetid,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
239	default "landlock,lockdown,yama,loadpin,safesetid,bpf" if DEFAULT_SECURITY_DAC
240	default "landlock,lockdown,yama,loadpin,safesetid,selinux,smack,tomoyo,apparmor,bpf"
241	help
242	  A comma-separated list of LSMs, in initialization order.
243	  Any LSMs left off this list, except for those with order
244	  LSM_ORDER_FIRST and LSM_ORDER_LAST, which are always enabled
245	  if selected in the kernel configuration, will be ignored.
246	  This can be controlled at boot with the "lsm=" parameter.
247
248	  If unsure, leave this as the default.
249
250source "security/Kconfig.hardening"
251
252endmenu
253
254