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 PAGE_TABLE_ISOLATION
58	bool "Remove the kernel mapping in user mode"
59	default y
60	depends on (X86_64 || X86_PAE) && !UML
61	help
62	  This feature reduces the number of hardware side channels by
63	  ensuring that the majority of kernel addresses are not mapped
64	  into userspace.
65
66	  See Documentation/x86/pti.rst for more details.
67
68config SECURITY_INFINIBAND
69	bool "Infiniband Security Hooks"
70	depends on SECURITY && INFINIBAND
71	help
72	  This enables the Infiniband security hooks.
73	  If enabled, a security module can use these hooks to
74	  implement Infiniband access controls.
75	  If you are unsure how to answer this question, answer N.
76
77config SECURITY_NETWORK_XFRM
78	bool "XFRM (IPSec) Networking Security Hooks"
79	depends on XFRM && SECURITY_NETWORK
80	help
81	  This enables the XFRM (IPSec) networking security hooks.
82	  If enabled, a security module can use these hooks to
83	  implement per-packet access controls based on labels
84	  derived from IPSec policy.  Non-IPSec communications are
85	  designated as unlabelled, and only sockets authorized
86	  to communicate unlabelled data can send without using
87	  IPSec.
88	  If you are unsure how to answer this question, answer N.
89
90config SECURITY_PATH
91	bool "Security hooks for pathname based access control"
92	depends on SECURITY
93	help
94	  This enables the security hooks for pathname based access control.
95	  If enabled, a security module can use these hooks to
96	  implement pathname based access controls.
97	  If you are unsure how to answer this question, answer N.
98
99config INTEL_TXT
100	bool "Enable Intel(R) Trusted Execution Technology (Intel(R) TXT)"
101	depends on HAVE_INTEL_TXT
102	help
103	  This option enables support for booting the kernel with the
104	  Trusted Boot (tboot) module. This will utilize
105	  Intel(R) Trusted Execution Technology to perform a measured launch
106	  of the kernel. If the system does not support Intel(R) TXT, this
107	  will have no effect.
108
109	  Intel TXT will provide higher assurance of system configuration and
110	  initial state as well as data reset protection.  This is used to
111	  create a robust initial kernel measurement and verification, which
112	  helps to ensure that kernel security mechanisms are functioning
113	  correctly. This level of protection requires a root of trust outside
114	  of the kernel itself.
115
116	  Intel TXT also helps solve real end user concerns about having
117	  confidence that their hardware is running the VMM or kernel that
118	  it was configured with, especially since they may be responsible for
119	  providing such assurances to VMs and services running on it.
120
121	  See <https://www.intel.com/technology/security/> for more information
122	  about Intel(R) TXT.
123	  See <http://tboot.sourceforge.net> for more information about tboot.
124	  See Documentation/x86/intel_txt.rst for a description of how to enable
125	  Intel TXT support in a kernel boot.
126
127	  If you are unsure as to whether this is required, answer N.
128
129config LSM_MMAP_MIN_ADDR
130	int "Low address space for LSM to protect from user allocation"
131	depends on SECURITY && SECURITY_SELINUX
132	default 32768 if ARM || (ARM64 && COMPAT)
133	default 65536
134	help
135	  This is the portion of low virtual memory which should be protected
136	  from userspace allocation.  Keeping a user from writing to low pages
137	  can help reduce the impact of kernel NULL pointer bugs.
138
139	  For most ia64, ppc64 and x86 users with lots of address space
140	  a value of 65536 is reasonable and should cause no problems.
141	  On arm and other archs it should not be higher than 32768.
142	  Programs which use vm86 functionality or have some need to map
143	  this low address space will need the permission specific to the
144	  systems running LSM.
145
146config HAVE_HARDENED_USERCOPY_ALLOCATOR
147	bool
148	help
149	  The heap allocator implements __check_heap_object() for
150	  validating memory ranges against heap object sizes in
151	  support of CONFIG_HARDENED_USERCOPY.
152
153config HARDENED_USERCOPY
154	bool "Harden memory copies between kernel and userspace"
155	depends on HAVE_HARDENED_USERCOPY_ALLOCATOR
156	imply STRICT_DEVMEM
157	help
158	  This option checks for obviously wrong memory regions when
159	  copying memory to/from the kernel (via copy_to_user() and
160	  copy_from_user() functions) by rejecting memory ranges that
161	  are larger than the specified heap object, span multiple
162	  separately allocated pages, are not on the process stack,
163	  or are part of the kernel text. This kills entire classes
164	  of heap overflow exploits and similar kernel memory exposures.
165
166config HARDENED_USERCOPY_FALLBACK
167	bool "Allow usercopy whitelist violations to fallback to object size"
168	depends on HARDENED_USERCOPY
169	default y
170	help
171	  This is a temporary option that allows missing usercopy whitelists
172	  to be discovered via a WARN() to the kernel log, instead of
173	  rejecting the copy, falling back to non-whitelisted hardened
174	  usercopy that checks the slab allocation size instead of the
175	  whitelist size. This option will be removed once it seems like
176	  all missing usercopy whitelists have been identified and fixed.
177	  Booting with "slab_common.usercopy_fallback=Y/N" can change
178	  this setting.
179
180config HARDENED_USERCOPY_PAGESPAN
181	bool "Refuse to copy allocations that span multiple pages"
182	depends on HARDENED_USERCOPY
183	depends on EXPERT
184	help
185	  When a multi-page allocation is done without __GFP_COMP,
186	  hardened usercopy will reject attempts to copy it. There are,
187	  however, several cases of this in the kernel that have not all
188	  been removed. This config is intended to be used only while
189	  trying to find such users.
190
191config FORTIFY_SOURCE
192	bool "Harden common str/mem functions against buffer overflows"
193	depends on ARCH_HAS_FORTIFY_SOURCE
194	help
195	  Detect overflows of buffers in common string and memory functions
196	  where the compiler can determine and validate the buffer sizes.
197
198config STATIC_USERMODEHELPER
199	bool "Force all usermode helper calls through a single binary"
200	help
201	  By default, the kernel can call many different userspace
202	  binary programs through the "usermode helper" kernel
203	  interface.  Some of these binaries are statically defined
204	  either in the kernel code itself, or as a kernel configuration
205	  option.  However, some of these are dynamically created at
206	  runtime, or can be modified after the kernel has started up.
207	  To provide an additional layer of security, route all of these
208	  calls through a single executable that can not have its name
209	  changed.
210
211	  Note, it is up to this single binary to then call the relevant
212	  "real" usermode helper binary, based on the first argument
213	  passed to it.  If desired, this program can filter and pick
214	  and choose what real programs are called.
215
216	  If you wish for all usermode helper programs are to be
217	  disabled, choose this option and then set
218	  STATIC_USERMODEHELPER_PATH to an empty string.
219
220config STATIC_USERMODEHELPER_PATH
221	string "Path to the static usermode helper binary"
222	depends on STATIC_USERMODEHELPER
223	default "/sbin/usermode-helper"
224	help
225	  The binary called by the kernel when any usermode helper
226	  program is wish to be run.  The "real" application's name will
227	  be in the first argument passed to this program on the command
228	  line.
229
230	  If you wish for all usermode helper programs to be disabled,
231	  specify an empty string here (i.e. "").
232
233source "security/selinux/Kconfig"
234source "security/smack/Kconfig"
235source "security/tomoyo/Kconfig"
236source "security/apparmor/Kconfig"
237source "security/loadpin/Kconfig"
238source "security/yama/Kconfig"
239source "security/safesetid/Kconfig"
240source "security/lockdown/Kconfig"
241
242source "security/integrity/Kconfig"
243
244choice
245	prompt "First legacy 'major LSM' to be initialized"
246	default DEFAULT_SECURITY_SELINUX if SECURITY_SELINUX
247	default DEFAULT_SECURITY_SMACK if SECURITY_SMACK
248	default DEFAULT_SECURITY_TOMOYO if SECURITY_TOMOYO
249	default DEFAULT_SECURITY_APPARMOR if SECURITY_APPARMOR
250	default DEFAULT_SECURITY_DAC
251
252	help
253	  This choice is there only for converting CONFIG_DEFAULT_SECURITY
254	  in old kernel configs to CONFIG_LSM in new kernel configs. Don't
255	  change this choice unless you are creating a fresh kernel config,
256	  for this choice will be ignored after CONFIG_LSM has been set.
257
258	  Selects the legacy "major security module" that will be
259	  initialized first. Overridden by non-default CONFIG_LSM.
260
261	config DEFAULT_SECURITY_SELINUX
262		bool "SELinux" if SECURITY_SELINUX=y
263
264	config DEFAULT_SECURITY_SMACK
265		bool "Simplified Mandatory Access Control" if SECURITY_SMACK=y
266
267	config DEFAULT_SECURITY_TOMOYO
268		bool "TOMOYO" if SECURITY_TOMOYO=y
269
270	config DEFAULT_SECURITY_APPARMOR
271		bool "AppArmor" if SECURITY_APPARMOR=y
272
273	config DEFAULT_SECURITY_DAC
274		bool "Unix Discretionary Access Controls"
275
276endchoice
277
278config LSM
279	string "Ordered list of enabled LSMs"
280	default "lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
281	default "lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
282	default "lockdown,yama,loadpin,safesetid,integrity,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
283	default "lockdown,yama,loadpin,safesetid,integrity,bpf" if DEFAULT_SECURITY_DAC
284	default "lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor,bpf"
285	help
286	  A comma-separated list of LSMs, in initialization order.
287	  Any LSMs left off this list will be ignored. This can be
288	  controlled at boot with the "lsm=" parameter.
289
290	  If unsure, leave this as the default.
291
292source "security/Kconfig.hardening"
293
294endmenu
295
296