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
22choice
23	prompt "Allow /proc/pid/mem access override"
24	default PROC_MEM_ALWAYS_FORCE
25	help
26	  Traditionally /proc/pid/mem allows users to override memory
27	  permissions for users like ptrace, assuming they have ptrace
28	  capability.
29
30	  This allows people to limit that - either never override, or
31	  require actual active ptrace attachment.
32
33	  Defaults to the traditional behavior (for now)
34
35config PROC_MEM_ALWAYS_FORCE
36	bool "Traditional /proc/pid/mem behavior"
37	help
38	  This allows /proc/pid/mem accesses to override memory mapping
39	  permissions if you have ptrace access rights.
40
41config PROC_MEM_FORCE_PTRACE
42	bool "Require active ptrace() use for access override"
43	help
44	  This allows /proc/pid/mem accesses to override memory mapping
45	  permissions for active ptracers like gdb.
46
47config PROC_MEM_NO_FORCE
48	bool "Never"
49	help
50	  Never override memory mapping permissions
51
52endchoice
53
54config SECURITY
55	bool "Enable different security models"
56	depends on SYSFS
57	depends on MULTIUSER
58	help
59	  This allows you to choose different security modules to be
60	  configured into your kernel.
61
62	  If this option is not selected, the default Linux security
63	  model will be used.
64
65	  If you are unsure how to answer this question, answer N.
66
67config SECURITYFS
68	bool "Enable the securityfs filesystem"
69	help
70	  This will build the securityfs filesystem.  It is currently used by
71	  various security modules (AppArmor, IMA, SafeSetID, TOMOYO, TPM).
72
73	  If you are unsure how to answer this question, answer N.
74
75config SECURITY_NETWORK
76	bool "Socket and Networking Security Hooks"
77	depends on SECURITY
78	help
79	  This enables the socket and networking security hooks.
80	  If enabled, a security module can use these hooks to
81	  implement socket and networking access controls.
82	  If you are unsure how to answer this question, answer N.
83
84config SECURITY_INFINIBAND
85	bool "Infiniband Security Hooks"
86	depends on SECURITY && INFINIBAND
87	help
88	  This enables the Infiniband security hooks.
89	  If enabled, a security module can use these hooks to
90	  implement Infiniband access controls.
91	  If you are unsure how to answer this question, answer N.
92
93config SECURITY_NETWORK_XFRM
94	bool "XFRM (IPSec) Networking Security Hooks"
95	depends on XFRM && SECURITY_NETWORK
96	help
97	  This enables the XFRM (IPSec) networking security hooks.
98	  If enabled, a security module can use these hooks to
99	  implement per-packet access controls based on labels
100	  derived from IPSec policy.  Non-IPSec communications are
101	  designated as unlabelled, and only sockets authorized
102	  to communicate unlabelled data can send without using
103	  IPSec.
104	  If you are unsure how to answer this question, answer N.
105
106config SECURITY_PATH
107	bool "Security hooks for pathname based access control"
108	depends on SECURITY
109	help
110	  This enables the security hooks for pathname based access control.
111	  If enabled, a security module can use these hooks to
112	  implement pathname based access controls.
113	  If you are unsure how to answer this question, answer N.
114
115config INTEL_TXT
116	bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
117	depends on HAVE_INTEL_TXT
118	help
119	  This option enables support for booting the kernel with the
120	  Trusted Boot (tboot) module. This will utilize
121	  Intel(R) Trusted Execution Technology to perform a measured launch
122	  of the kernel. If the system does not support Intel(R) TXT, this
123	  will have no effect.
124
125	  Intel TXT will provide higher assurance of system configuration and
126	  initial state as well as data reset protection.  This is used to
127	  create a robust initial kernel measurement and verification, which
128	  helps to ensure that kernel security mechanisms are functioning
129	  correctly. This level of protection requires a root of trust outside
130	  of the kernel itself.
131
132	  Intel TXT also helps solve real end user concerns about having
133	  confidence that their hardware is running the VMM or kernel that
134	  it was configured with, especially since they may be responsible for
135	  providing such assurances to VMs and services running on it.
136
137	  See <https://www.intel.com/technology/security/> for more information
138	  about Intel(R) TXT.
139	  See <http://tboot.sourceforge.net> for more information about tboot.
140	  See Documentation/arch/x86/intel_txt.rst for a description of how to enable
141	  Intel TXT support in a kernel boot.
142
143	  If you are unsure as to whether this is required, answer N.
144
145config LSM_MMAP_MIN_ADDR
146	int "Low address space for LSM to protect from user allocation"
147	depends on SECURITY && SECURITY_SELINUX
148	default 32768 if ARM || (ARM64 && COMPAT)
149	default 65536
150	help
151	  This is the portion of low virtual memory which should be protected
152	  from userspace allocation.  Keeping a user from writing to low pages
153	  can help reduce the impact of kernel NULL pointer bugs.
154
155	  For most ia64, ppc64 and x86 users with lots of address space
156	  a value of 65536 is reasonable and should cause no problems.
157	  On arm and other archs it should not be higher than 32768.
158	  Programs which use vm86 functionality or have some need to map
159	  this low address space will need the permission specific to the
160	  systems running LSM.
161
162config HARDENED_USERCOPY
163	bool "Harden memory copies between kernel and userspace"
164	imply STRICT_DEVMEM
165	help
166	  This option checks for obviously wrong memory regions when
167	  copying memory to/from the kernel (via copy_to_user() and
168	  copy_from_user() functions) by rejecting memory ranges that
169	  are larger than the specified heap object, span multiple
170	  separately allocated pages, are not on the process stack,
171	  or are part of the kernel text. This prevents entire classes
172	  of heap overflow exploits and similar kernel memory exposures.
173
174config FORTIFY_SOURCE
175	bool "Harden common str/mem functions against buffer overflows"
176	depends on ARCH_HAS_FORTIFY_SOURCE
177	# https://github.com/llvm/llvm-project/issues/53645
178	depends on !CC_IS_CLANG || !X86_32
179	help
180	  Detect overflows of buffers in common string and memory functions
181	  where the compiler can determine and validate the buffer sizes.
182
183config STATIC_USERMODEHELPER
184	bool "Force all usermode helper calls through a single binary"
185	help
186	  By default, the kernel can call many different userspace
187	  binary programs through the "usermode helper" kernel
188	  interface.  Some of these binaries are statically defined
189	  either in the kernel code itself, or as a kernel configuration
190	  option.  However, some of these are dynamically created at
191	  runtime, or can be modified after the kernel has started up.
192	  To provide an additional layer of security, route all of these
193	  calls through a single executable that can not have its name
194	  changed.
195
196	  Note, it is up to this single binary to then call the relevant
197	  "real" usermode helper binary, based on the first argument
198	  passed to it.  If desired, this program can filter and pick
199	  and choose what real programs are called.
200
201	  If you wish for all usermode helper programs are to be
202	  disabled, choose this option and then set
203	  STATIC_USERMODEHELPER_PATH to an empty string.
204
205config STATIC_USERMODEHELPER_PATH
206	string "Path to the static usermode helper binary"
207	depends on STATIC_USERMODEHELPER
208	default "/sbin/usermode-helper"
209	help
210	  The binary called by the kernel when any usermode helper
211	  program is wish to be run.  The "real" application's name will
212	  be in the first argument passed to this program on the command
213	  line.
214
215	  If you wish for all usermode helper programs to be disabled,
216	  specify an empty string here (i.e. "").
217
218source "security/selinux/Kconfig"
219source "security/smack/Kconfig"
220source "security/tomoyo/Kconfig"
221source "security/apparmor/Kconfig"
222source "security/loadpin/Kconfig"
223source "security/yama/Kconfig"
224source "security/safesetid/Kconfig"
225source "security/lockdown/Kconfig"
226source "security/landlock/Kconfig"
227source "security/ipe/Kconfig"
228
229source "security/integrity/Kconfig"
230
231choice
232	prompt "First legacy 'major LSM' to be initialized"
233	default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
234	default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
235	default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
236	default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
237	default DEFAULT_SECURITY_DAC
238
239	help
240	  This choice is there only for converting CONFIG_DEFAULT_SECURITY
241	  in old kernel configs to CONFIG_LSM in new kernel configs. Don't
242	  change this choice unless you are creating a fresh kernel config,
243	  for this choice will be ignored after CONFIG_LSM has been set.
244
245	  Selects the legacy "major security module" that will be
246	  initialized first. Overridden by non-default CONFIG_LSM.
247
248	config DEFAULT_SECURITY_SELINUX
249		bool "SELinux" if SECURITY_SELINUX=y
250
251	config DEFAULT_SECURITY_SMACK
252		bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
253
254	config DEFAULT_SECURITY_TOMOYO
255		bool "TOMOYO" if SECURITY_TOMOYO=y
256
257	config DEFAULT_SECURITY_APPARMOR
258		bool "AppArmor" if SECURITY_APPARMOR=y
259
260	config DEFAULT_SECURITY_DAC
261		bool "Unix Discretionary Access Controls"
262
263endchoice
264
265config LSM
266	string "Ordered list of enabled LSMs"
267	default "landlock,lockdown,yama,loadpin,safesetid,smack,selinux,tomoyo,apparmor,ipe,bpf" if DEFAULT_SECURITY_SMACK
268	default "landlock,lockdown,yama,loadpin,safesetid,apparmor,selinux,smack,tomoyo,ipe,bpf" if DEFAULT_SECURITY_APPARMOR
269	default "landlock,lockdown,yama,loadpin,safesetid,tomoyo,ipe,bpf" if DEFAULT_SECURITY_TOMOYO
270	default "landlock,lockdown,yama,loadpin,safesetid,ipe,bpf" if DEFAULT_SECURITY_DAC
271	default "landlock,lockdown,yama,loadpin,safesetid,selinux,smack,tomoyo,apparmor,ipe,bpf"
272	help
273	  A comma-separated list of LSMs, in initialization order.
274	  Any LSMs left off this list, except for those with order
275	  LSM_ORDER_FIRST and LSM_ORDER_LAST, which are always enabled
276	  if selected in the kernel configuration, will be ignored.
277	  This can be controlled at boot with the "lsm=" parameter.
278
279	  If unsure, leave this as the default.
280
281source "security/Kconfig.hardening"
282
283endmenu
284
285